document_title: Eye surgery

question_text: a procedure involving the surgical repair of the eyelid is called

text: Eye surgery

text: Preparation and precautions[edit]

text: Since the eye is heavily supplied by nerves, anesthesia is essential. Local anesthesia is most commonly used. Topical anesthesia using lidocaine topical gel are often used for quick procedures. Since topical anesthesia requires cooperation from the patient, general anesthesia is often used for children, traumatic eye injuries, major orbitotomies and for apprehensive patients. The physician administering anesthesia, or a nurse anesthetist or anesthetist assistant with expertise in anesthesia of the eye, monitors the patient's cardiovascular status. Sterile precautions are taken to prepare the area for surgery and lower the risk of infection. These precautions include the use of antiseptics, such as povidone-iodine, and sterile drapes, gowns and gloves.

text: Laser eye surgery[edit]

text: Although the terms laser eye surgery and refractive surgery are commonly used as if they were interchangeable, this is not the case. Lasers may be used to treat nonrefractive conditions (e.g. to seal a retinal tear).[3] Laser eye surgery or laser corneal surgery is a medical procedure that uses a laser to reshape the surface of the eye. This is done to correct myopia (short-sightedness), hypermetropia (long sightedness) and astigmatism (uneven curvature of the eye's surface). It is important to note that refractive surgery is not compatible with everyone, and rarely people may find that eyewear is still needed after surgery.[4]

text: Recent developments also include procedures that can change eye color from brown to blue.[5][6]

text: Cataract surgery[edit]

text: A cataract is an opacification or cloudiness of the eye's crystalline lens due to aging, disease, or trauma that typically prevents light from forming a clear image on the retina. If visual loss is significant, surgical removal of the lens may be warranted, with lost optical power usually replaced with a plastic intraocular lens (IOL). Owing to the high prevalence of cataracts, cataract extraction is the most common eye surgery. Rest after surgery is recommended.[7]

text: Glaucoma surgery[edit]

text: Glaucoma is a group of diseases affecting the optic nerve that results in vision loss and is frequently characterized by raised intraocular pressure (IOP). There are many types of glaucoma surgery, and variations or combinations of those types, that facilitate the escape of excess aqueous humor from the eye to lower intraocular pressure, and a few that lower IOP by decreasing the production of aqueous humor.

text: Canaloplasty[edit]

text: Canaloplasty is an advanced, nonpenetrating procedure designed to enhance drainage through the eye’s natural drainage system to provide sustained reduction of IOP. Canaloplasty utilizes microcatheter technology in a simple and minimally invasive procedure. To perform a canaloplasty, an Ophthalmologist creates a tiny incision to gain access to a canal in the eye. A microcatheter circumnavigates the canal around the iris, enlarging the main drainage channel and its smaller collector channels through the injection of a sterile, gel-like material called viscoelastic. The catheter is then removed and a suture is placed within the canal and tightened. By opening up the canal, the pressure inside the eye can be reduced.[8][9][10][11]

text: Refractive surgery[edit]

text: Refractive surgery aims to correct errors of refraction in the eye, reducing or eliminating the need for corrective lenses

text:
Keratomilleusis is a method of reshaping the cornea surface to change its optical power. A disc of cornea is shaved off, quickly frozen, lathe-ground, then returned to its original power.
Automated lamellar keratoplasty (ALK)
Laser assisted in-situ keratomileusis (LASIK)[12]
Laser assisted sub-epithelial keratomileusis (LASEK), a.k.a. Epi-LASIK
Photorefractive keratectomy (PRK)[13]
Laser thermal keratoplasty (LTK)
Conductive keratoplasty (CK) uses radio frequency waves to shrink corneal collagen. It is used to treat mild to moderate hyperopia.[12]
Limbal relaxing incisions (LRI) to correct minor astigmatism
Astigmatic keratotomy (AK), a.k.a. Arcuate keratotomy or Transverse keratotomy
Radial keratotomy (RK)
Mini asymmetric radial keratotomy
Hexagonal keratotomy (HK)
Epikeratophakia is the removal of the corneal epithelium and replacement with a lathe cut corneal button.[14]
Intracorneal rings (ICRs), or corneal ring segments
Implantable contact lenses
Presbyopia reversal
Anterior ciliary sclerotomy (ACS)
Scleral reinforcement surgery for the mitigation of degenerative myopia

text: Corneal surgery[edit]

text: Corneal surgery includes most refractive surgery as well as the following:

text:
Corneal transplant surgery, is used to remove a cloudy/diseased cornea and replace it with a clear donor cornea.[14]
Penetrating keratoplasty (PK)
Keratoprosthesis(KPro)
Phototherapeutic keratectomy (PTK)[15]
Pterygium excision
Corneal tattooing
Osteo-Odonto-Keratoprosthesis (OOKP), in which support for an artificial cornea is created from a tooth and its surrounding jawbone.[16] This is a still-experimental procedure used for patients with severely damaged eyes, generally from burns.[17]
Eye color change surgery through an iris implant, known as Brightocular, or stripping away the top layer of eye pigment, known as the Stroma procedure.[18]

text: Vitreo-retinal surgery[edit]

text: Vitreo-retinal surgery includes the following

text:
Vitrectomy[19]

Anterior vitrectomy is the removal of the front portion of vitreous tissue. It is used for preventing or treating vitreous loss during cataract or corneal surgery, or to remove misplaced vitreous in conditions such as aphakia pupillary block glaucoma.
Pars plana vitrectomy (PPV), or trans pars plana vitrectomy (TPPV), is a procedure to remove vitreous opacities and membranes through a pars plana incision. It is frequently combined with other intraocular procedures for the treatment of giant retinal tears, tractional retinal detachments, and posterior vitreous detachments.

Pan retinal photocoagulation (PRP) is a type of photocoagulation therapy used in the treatment of diabetic retinopathy.[20]
Retinal detachment repair

Ignipuncture is an obsolete procedure that involves cauterization of the retina with a very hot pointed instrument.[21]
A scleral buckle is used in the repair of a retinal detachment to indent or "buckle" the sclera inward, usually by sewing a piece of preserved sclera or silicone rubber to its surface.[22]
Laser photocoagulation, or photocoagulation therapy, is the use of a laser to seal a retinal tear.[20]
Pneumatic retinopexy
Retinal cryopexy, or retinal cryotherapy, is a procedure that uses intense cold to induce a chorioretinal scar and to destroy retinal or choroidal tissue.[23]

Macular hole repair
Partial lamellar sclerouvectomy[24]
Partial lamellar sclerocyclochoroidectomy
Partial lamellar sclerochoroidectomy
Posterior sclerotomy is an opening made into the vitreous through the sclera, as for detached retina or the removal of a foreign body [1].
Radial optic neurotomy
macular translocation surgery

through 360 degree retinotomy
through scleral imbrication technique

text: Eye muscle surgery[edit]

text: With approximately 1.2 million procedures each year, extraocular muscle surgery is the third most common eye surgery in the United States [2].

text:
Eye muscle surgery typically corrects strabismus and includes the following[25] [3]:

Loosening / weakening procedures

Recession involves moving the insertion of a muscle posteriorly towards its origin.
Myectomy
Myotomy
Tenectomy
Tenotomy

Tightening / strengthening procedures

Resection
Tucking
Advancement is the movement of an eye muscle from its original place of attachment on the eyeball to a more forward position.

Transposition / repositioning procedures
Adjustable suture surgery is a method of reattaching an extraocular muscle by means of a stitch that can be shortened or lengthened within the first post-operative day, to obtain better ocular alignment [4].

text: Oculoplastic surgery[edit]

text: Oculoplastic surgery, or oculoplastics, is the subspecialty of ophthalmology that deals with the reconstruction of the eye and associated structures. Oculoplastic surgeons perform procedures such as the repair of droopy eyelids (blepharoplasty)[5], repair of tear duct obstructions, orbital fracture repairs, removal of tumors in and around the eyes, and facial rejuvenation procedures including laser skin resurfacing, eye lifts, brow lifts, and even facelifts. Common procedures are:

text: Eyelid surgery[edit]

text:
Blepharoplasty (Eyelift)

Blepharoplasty is plastic surgery of the eyelids to remove excessive skin or subcutaneous fat.[26]

Asian blepharoplasty

Ptosis repair for droopy eyelid

Ectropion repair [6]

Entropion repair
Canthal resection

A canthectomy is the surgical removal of tissue at the junction of the upper and lower eyelids.[27]
Cantholysis is the surgical division of the canthus.[27]
Canthopexy
A canthoplasty is plastic surgery at the canthus.[27]
A canthorrhaphy is suturing of the outer canthus to shorten the palpebral fissure.[27]
A canthotomy is the surgical division of the canthus, usually the outer canthus.[27]

A lateral canthotomy is the surgical division of the outer canthus.

Epicanthoplasty
Tarsorrhaphy is a procedure in which the eyelids are partially sewn together to narrow the opening (i.e. palpebral fissure).

text: Orbital surgery[edit]

text:
Orbital reconstruction / Ocular prosthetics (False Eyes)
Orbital decompression for Grave's Disease. Grave's Disease is a condition (often associated with over-active thyroid problems) in which the eye muscles swell. Because the eye socket is bone, there is nowhere for the swelling to be accommodated and as a result the eye is pushed forward into a protruded position. In some patients this is very pronounced. Orbitial decompression involves removing some bone from the eye socket to open up one or more sinuses and so make space for the swollen tissue and allowing the eye to move back into normal position.

text: Other oculoplastic surgery[edit]

text:
Botox injections
Ultrapeel Microdermabrasion
Endoscopic forehead and browlift
Face lift (Rhytidectomy)
Liposuction of the face and neck
Browplasty[28]

text: Surgery involving the lacrimal apparatus[edit]

text:
A dacryocystorhinostomy (DCR) or dacryocystorhinotomy is a procedure to restore the flow of tears into the nose from the lacrimal sac when the nasolacrimal duct does not function.[27][29]
Canaliculodacryocystostomy is a surgical correction for a congenitally blocked tear duct in which the closed segment is excised and the open end is joined to the lacrimal sac.[27][30]
Canaliculotomy involves slitting of the lacrimal punctum and canaliculus for the relief of epiphora[27]
A dacryoadenectomy is the surgical removal of a lacrimal gland.[27]
A dacryocystectomy is the surgical removal of a part of the lacrimal sac.[27]
A dacryocystostomy is an incision into the lacrimal sac, usually to promote drainage.[27]
A dacryocystotomy is an incision into the lacrimal sac.[27]

text: Eye removal[edit]

text:
An enucleation is the removal of the eye leaving the eye muscles and remaining orbital contents intact.[31]
An evisceration is the removal of the eye's contents, leaving the scleral shell intact. Usually performed to reduce pain in a blind eye.[32]
An exenteration is the removal of the entire orbital contents, including the eye, extraocular muscles, fat, and connective tissues; usually for malignant orbital tumors.[33]

text: Other surgery[edit]

text: Many of these described procedures are historical and are not recommended due to a risk of complications. Particularly, these include operations done on ciliary body in an attempt to control glaucoma, since highly safer surgeries for glaucoma, including lasers, non-penetrating surgery, guarded filtration surgery and seton valve implants have been invented.

text:
A ciliarotomy is a surgical division of the ciliary zone in the treatment of glaucoma.[27]
A ciliectomy is 1) the surgical removal of part of the ciliary body, or 2) the surgical removal of part of a margin of an eyelid containing the roots of the eyelashes.[27]
A ciliotomy is a surgical section of the ciliary nerves.[27]
A conjunctivoanstrostomy is an opening made from the inferior conjuctival cul-de-sac into the maxillary sinus for the treatment of epiphora.[27]
Conjuctivoplasty is plastic surgery of the conjunctiva.[27]
A conjunctivorhinostomy is a surgical correction of the total obstruction of a lacrimal canaliculus by which the conjuctiva is anastomosed with the nasal cavity to improve tear flow.[27]
A corectomedialysis, or coretomedialysis, is an excision of a small portion of the iris at its junction with the ciliary body to form an artificial pupil.[27]
A corectomy, or coretomy, is any surgical cutting operation on the iris at the pupil.[27]
A corelysis is a surgical detachment of adhesions of the iris to the capsule of the crystalline lens or cornea.[27]
A coremorphosis is the surgical formation of an artificial pupil.[27]
A coreplasty, or coreoplasty, is plastic surgery of the iris, usually for the formation of an artificial pupil.[27]
A coreoplasy, or laser pupillomydriasis, is any procedure that changes the size or shape of the pupil.[32]
A cyclectomy is an excision of portion of the ciliary body.[27]
A cyclotomy, or cyclicotomy, is a surgical incision of the ciliary body, usually for the relief of glaucoma.[27]
A cycloanemization is a surgical obliteration of the long ciliary arteries in the treatment of glaucoma.[27]
An iridectomesodialysis is the formation of an artificial pupil by detaching and excising a portion of the iris at its periphery.[27]
An iridodialysis, sometimes known as a coredialysis, is a localized separation or tearing away of the iris from its attachment to the ciliary body.[27][32]
An iridencleisis, or corenclisis, is a surgical procedure for glaucoma in which a portion of the iris is incised and incarcerated in a limbal incision.[27] (Subdivided into basal iridencleisis and total iridencleisis.[34])
An iridesis is a surgical procedure in which a portion of the iris is brought through and incarcerated in a corneal incision in order to reposition the pupil.[27][7]
An iridocorneosclerectomy is the surgical removal of a portion of the iris, the cornea, and the sclera.[27]
An iridocyclectomy is the surgical removal of the iris and the ciliary body.[27]
An iridocystectomy is the surgical removal of a portion of the iris to form an artificial pupil.[27]
An iridosclerectomy is the surgical removal of a portion of the sclera and a portion of the iris in the region of the limbus for the treatment of glaucoma.[27]
An iridosclerotomy is the surgical puncture of the sclera and the margin of the iris for the treatment of glaucoma.[27]
A rhinommectomy is the surgical removal of a portion of the internal canthus.[27]
A trepanotrabeculectomy is used in the treatment of chronic open and chronic closed angle glaucoma.[34]


document_title: Protoplasm

question_text: who coined the term protoplasm for living matter

root

text: Protoplasm

text: Terminology[edit]

text: Besides "protoplasm", many other related terms and distinctions were used for the cell contents over time:[8][9]

tag: p

text:
Urschleim (Oken, 1802, 1809),[10][11]
Protoplasma (Purkinje, 1840, von Mohl, 1846),[12][13]
Primordialschlauch (primordial utricle, von Mohl, 1846),[13]
sarcode (Dujardin, 1835, 1841),[14][15]
Cytoplasma (Kölliker, 1863),[16]
Hautschicht/Körnerschicht (ectoplasm/endoplasm, Pringsheim, 1854; Hofmeister, 1867),[17][18]
Grundsubstanz (ground substance, Cienkowski, 1863),[19]
metaplasm/protoplasm (Hanstein, 1868),[20]
deutoplasm/protoplasm (van Beneden, 1870),[21]
bioplasm (Beale, 1872),[22]
paraplasm/protoplasm (Kupffer, 1875),[23]
inter-filar substance theory (Velten, 1876)[24]
Hyaloplasma (Pfeffer, 1877),[25]
Protoplast (Hanstein, 1880),[26]
Enchylema/Hyaloplasma (Hanstein, 1880),[27]
Kleinkörperchen or Mikrosomen (small bodies or microsomes, Hanstein, 1882),[28]
paramitome (Flemming, 1882),[29]
Idioplasma (Nageli, 1884),[9]
Zwischensubstanz (inter-alveolar substance, Bütschli, 1892),[30]
Grundplasma (ground plasma, Schütt, 1895),[31]
ergastoplasme (Garnier, 1897),[9]
phaneroplasm/cryptoplasm (Seifriz, 1931),[32]
cytoplasmic matrix (Munson, 1899; zytoplasmatische Matrix, Bergmann, 1956),[33][34]
Protoplasma- oder Zelleinschlüsse (protoplasmic or cellular inclusions, Szymonowicz, 1901),[35][36]
kinoplasm/trophoplasm (Strasburger et at., 1912),[37]
cytosol (Lardy, 1965).[38]

tag: ul

text: History[edit]

text: The word "protoplasm" comes from the Greek protos for first, and plasma for thing formed, and was originally used in religious contexts.[39] It was used in 1839 by J. E. Purkinje for the material of the animal embryo.[12][40] Later, in 1846 Hugo von Mohl redefined the term (also named as Primordialschlauch, "primordial utricle") to refer to the "tough, slimy, granular, semi-fluid" substance within plant cells, to distinguish this from the cell wall and the cell sap (Zellsaft) within the vacuole.[13][41][42] Thomas Huxley (1869) later referred to it as the "physical basis of life" and considered that the property of life resulted from the distribution of molecules within this substance.[43] The protoplasm became an "epistemic thing".[44] Its composition, however, was mysterious and there was much controversy over what sort of substance it was.[45]

text: In 1872, Beale created the vitalist term "bioplasm", to contrast with the materialism of Huxley.[22][46] In 1880, term protoplast was proposed by Hanstein (1880) for the entire cell, excluding the cell wall,[47][48] and some authors like Julius von Sachs (1882) preferred that name instead of cell.[49]

text: In 1965, lardy introduced the term "cytosol", later redefined to refer to the liquid inside cell.[38]

text: By the time Huxley wrote, a long-standing debate was largely settled over the fundamental unit of life: was it the cell or was it protoplasm? By the late 1860s, the debate was largely settled in favor of protoplasm. The cell was a container for protoplasm, the fundamental and universal material substance of life. Huxley's principal contribution was to establish protoplasm as incompatible with a vitalistic theory of life.[50] Attempts to investigate the origin of life through the creation of synthetic "protoplasm" in the laboratory were not successful.[51]

text: The idea that protoplasm of eukaryotes is simply divisible into a ground substance called "cytoplasm" and a structural body called the cell nucleus reflects the more primitive knowledge of cell structure that preceded the development of electron microscopy, when it seemed that cytoplasm was a homogeneous fluid and the existence of most sub-cellular compartments, or how cells maintain their shape, was unknown.[52] Today, it is known that the cell contents are structurally very complex and contain multiple organelles.

text: Description[edit]

text: This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (August 2016) (Learn how and when to remove this template message)

tag: table

text: Protoplasm is composed of a mixture of small molecules such as ions, amino acids, monosaccharides and water, and macromolecules such as nucleic acids, proteins, lipids and polysaccharides.[53] In eukaryotes the protoplasm surrounding the cell nucleus is known as the cytoplasm and that inside the nucleus as the nucleoplasm. In prokaryotes the material inside the plasma membrane is the bacterial cytoplasm, while in Gram-negative bacteria the region outside the plasma membrane but inside the outer membrane is the periplasm.

text: Protoplasm was said to exist in two forms: a liquid-like sol state or a jelly-like gel state.


document_title: Eyewitness testimony

question_text: a pioneer in the field of eye witness research

text: Eyewitness testimony

text: Reliability[edit]

text: Psychologists have probed the reliability of eyewitness testimony since the beginning of the 20th century.[1] One prominent pioneer was Hugo Münsterberg, whose controversial book On the Witness Stand (1908) demonstrated the fallibility of eyewitness accounts, but met with fierce criticism, particularly in legal circles.[2] His ideas did, however, gain popularity with the public.[3] Decades later, DNA testing would clear individuals convicted on the basis of errant eyewitness testimony. Studies by Scheck, Neufel, and Dwyer showed that many DNA-based exonerations involved eyewitness evidence.[4]

text: In the 1970s and '80s, Bob Buckhout showed inter alia that eyewitness conditions can, at least within ethical and other constraints, be simulated on university campuses,[2] and that large numbers of people can be mistaken: "Nearly 2,000 witnesses can be wrong" was the title of one paper.[5]

text: The mechanisms by which flaws enter eyewitness testimony are varied and can be quite subtle.

text: One way is a person's memory being influenced by things seen or heard after the crime occurred. This distortion is known as the post-event misinformation effect (Loftus and Palmer, 1974). After a crime occurs and an eyewitness comes forward, law enforcement tries to gather as much information as they can to avoid the influence that may come from the environment, such as the media. Many times when the crime is surrounded by much publicity, an eyewitness may experience source misattribution. Source misattribution occurs when a witness is incorrect about where or when they have the memory from. If a witness cannot correctly identify the source of their retrieved memory, the witness is seen as not reliable.

text: While some witnesses see the entirety of a crime happen in front of them, some witness only part of a crime. These witnesses are more likely to experience confirmation bias. Witness expectations are to blame for the distortion that may come from confirmation bias. For example, Lindholm and Christianson (1998) found that witnesses of a mock crime who did not witness the whole crime, nevertheless testified to what they expected would have happened. These expectations are normally similar across individuals due to the details of the environment.

text: Evaluating the credibility of eye-witness testimony falls on all individual jurors when such evidence is offered as testimony in a trial in the United States.[6] Research has shown that mock juries are often unable to distinguish between a false and accurate eyewitness testimony. "Jurors" often appear to correlate the confidence level of the witness with the accuracy of their testimony. An overview of this research by Laub and Bornstein shows this to be an inaccurate gauge of accuracy.[7]

text: Research[edit]

text: Research on eyewitness testimony looks at systematic variables or estimator variables. Estimator variables are characteristics of the witness, event, testimony, or testimony evaluators. Systematic variables are variables that are, or have the possibility of, being controlled by the criminal justice system. Both sets of variables can be manipulated and studied during research, but only system variables can be controlled in actual procedure.[1]

text: Estimator variables[edit]

text: Age of Witness[edit]

text: Among children, suggestibility can be very high. Suggestibility is the term used when a witness accepts information after the actual event and incorporates it into the memory of the event itself. Children's developmental level (generally correlated with age) causes them to be more easily influenced by leading questions, misinformation, and other post-event details. Compared to older children, preschool-age children are more likely to fall victim to suggestions without the ability to focus solely on the facts of what happened.[8]

text: In addition, a recent meta-analysis found that older adults (over age 65) tend to be more susceptible to memory distortion brought about by misleading post-event information, compared to young adults.[9]

text: Reconstructive memory[edit]

text: Many of the early studies of memory demonstrated how memories can fail to be accurate records of experiences. Because jurors and judges do not have access to the original event, it is important to know whether a testimony is based on actual experience or not.[10]

text: In a 1932 study, Frederic Bartlett demonstrated how serial reproduction of a story distorted accuracy in recalling information. He told participants a complicated Native American story and had them repeat it over a series of intervals. With each repetition, the stories were altered. Even when participants recalled accurate information, they filled in gaps with information that would fit their personal experiences. His work showed long term memory to be adaptable.[11] Bartlett viewed schemas as a major cause of this occurrence. People attempt to place past events into existing representations of the world, making the memory more coherent. Instead of remembering precise details about commonplace occurrences, a schema is developed. A schema is a generalization formed mentally based on experience.[12] The common use of these schemas suggests that memory is not an identical reproduction of experience, but a combination of actual events with already existing schemas. Bartlett summarized this issue, explaining

text: [M]emory is personal, not because of some intangible and hypothetical persisting ‘self ’, which receives and maintains innumerable traces, restimulating them whenever it needs; but because the mechanism of adult human memory demands an organisation of ‘schemata’ depending upon an interplay of appetites, instincts, interests and ideas peculiar to any given subject. Thus if, as in some pathological cases, these active sources of the ‘schemata’ get cut off from one another, the peculiar personal attributes of what is remembered fail to appear.[13]

text: Further research of schemas shows memories that are inconsistent with a schema decay faster than those that match up with a schema. Tuckey and Brewer found pieces of information that were inconsistent with a typical robbery decayed much faster than those that were schema consistent over a 12-week period, unless the information stood out as being extremely unusual. The use of schemas has been shown to increase the accuracy of recall of schema-consistent information but this comes at the cost of decreased recall of schema-inconsistent information.[14]

text: Misinformation effect[edit]

text: Elizabeth Loftus is one of the leading psychologists in the field of eyewitness testimony. She provided extensive research on this topic, revolutionizing the field with her bold stance that challenges the credibility of eyewitness testimony in court. She suggests that memory is not reliable and goes to great lengths to provide support for her arguments. She mainly focuses on the integration of misinformation with the original memory, forming a new memory. Some of her most convincing experiments support this claim:

text:
In one of her experiments, Loftus demonstrates that false verbal Information can integrate with original memory. Participants were presented with either truthful information or misleading information, and overall it showed that even the false information verbally presented became part of the memory after the participant was asked to recall details. This happens because of one of two reasons. First, it can alter the memory, incorporating the misinformation in with the actual, true memory. Second, the original memory and new information may both reside in memory in turn creating two conflicting ideas that compete in recall.[15]
Loftus conducted more experiments to prove the reliability of expert psychological testimony versus the accepted basic eyewitness testimony. It was found that jurors who hear about a violent crime are more likely to convict a defendant than of one from a nonviolent crime. To reduce this tendency for a juror to quickly accuse, and perhaps wrongly accuse, choosing to utilize expert psychological testimony causes the juror to critically appraise the eyewitness testimony, instead of quickly reaching a faulty verdict.[16]
Also, it has been shown that intelligence and gender has a role in the ability of accurate memory recall. Participants were measured in eyewitness performance in two areas: 1) the ability to resist adding misinformation to the memory and 2) accuracy of recalling the incident and person. It showed that when a woman was recalling information about a woman, the resistance to false details was higher and the recall was more accurate. If a man was recalling an incident involving a man, similarly the recall was more accurate. However, when dealing with opposite genders, the participants gave into the suggestibility (misinformation) more easily and demonstrated less accuracy.[17]
Facial recognition is a good indicator of how easily memories can be manipulated. In this specific experiment, if a misleading feature was presented, more than a third of the participants recalled that detail. With a specific detail, almost 70% of people claimed that it had been there, when it had not been present.[18]

tag: ol

text: Systematic variables[edit]

text: Type of questioning[edit]

text: As early as 1900, psychologists like Alfred Binet recorded how the phrasing of questioning during an investigation could alter witness response. Binet believed people were highly susceptible to suggestion, and called for a better approach to questioning witnesses.[19]

text: Studies conducted by Crombag (1996) discovered that in an incident involving a crew attempting to return to the airport but were unable to maintain flight and crashed into an 11 story apartment building. Though no cameras caught the moment of impact on film, many news stations covered the tragedy with footage taken after impact.[20] Ten months after the event, the researchers interviewed people about the crash. According to theories about flashbulb memory, the intense shock of the event should have made the memory of the event incredibly accurate. This same logic is often applied to those who witness a criminal act. To test this assumption, participants were asked questions that planted false information about the event. Fifty-five percent of subjects reported having watched the moment of impact on television, and recalled the moment the plane broke out in flames-even though it was impossible for them to have seen either of these occurrences. One researcher remarked, "[V]ery critical sense would have made our subjects realize that the implanted information could not possibly be true. We are still at a loss as to why so few of them realized this."

text: A survey of research on the matter confirm eyewitness testimony consistently changes over time and based on the type of questioning.[21] The approach investigators and lawyers take in their questioning has repeatedly shown to alter eyewitness response. One study showed changing certain words and phrases resulted in an increase in overall estimations of witnesses.[22]

text: Improving eyewitness testimony[edit]

text: Law enforcement, legal professions, and psychologists have worked together in attempts to make eyewitness testimony more reliable and accurate. Geiselman, Fisher, MacKinnon, and Holland saw much improvement in eyewitness memory with an interview procedure they referred to as the cognitive interview. The approach focuses on making witness aware of all events surrounding a crime without generating false memories or inventing details. In this tactic, the interviewer builds a rapport with the witness before asking any questions.[23] They then allow the witness to provide an open ended account of the situation. The interviewer then asks follow up questions to clarify the witness' account, reminding the witness it is acceptable to be unsure and move on.[1] This approach guides the witness over a rigid protocol. When implemented correctly, the CI showed more accuracy and efficiency without additional incorrect information being generated.[24]

text: Currently, this is the U.S. Department of Justice's suggested method for law enforcement officials to use in obtaining information from witnesses.[25] Programs training officers in this method have been developed outside the U.S. in many European countries, as well as Australia, New Zealand, and Israel.[26]

text: While some analysis of police interviewing technique reveals this change towards CI interviewing is not put into effect by many officials in the U.S.A. and the U.K., it is still considered to be the most effective means of decreasing error in eyewitness testimony.[1][27]

text: Procedural reforms[edit]

text: Experts debate what changes need to occur in the legal process in response to research on inaccuracy of eyewitness testimony.

text: Jury guidelines[edit]

text: It has been suggested that the jury be given a checklist to evaluate eyewitness testimony when given in court. R. J. Shafer offers this checklist for evaluating eyewitness testimony:

text:
How well could the eyewitness observe the thing he reports? Were his senses equal to the observation? Was his physical location suitable to sight, hearing, touch? Did he have the proper social ability to observe: did he understand the language, have other expertise required (e.g., law, military)?
When did he report in relation to his observation? Soon? Much later?
Are there additional clues to intended veracity? Was he indifferent on the subject reported, thus probably not intending distortion? Did he make statements damaging to himself, thus probably not seeking to distort? Did he give incidental or casual information, almost certainly not intended to mislead?
Do his statements seem inherently improbable: e.g., contrary to human nature, or in conflict with what we know?
Remember that some types of information are easier to observe and report on than others.
Are there inner contradictions in the testimony? [28]

text: Judge guidelines[edit]

text: In 2011, the New Jersey Supreme Court created new rules for the admissibility of eyewitness testimony in court. The new rules require judges to explain to jurors any influences that may heighten the risk for error in the testimony. The rules are part of nationwide court reform that attempts to improve the validity of eyewitness testimony and lower the rate of false conviction.[29]


document_title: Haters Back Off

question_text: when does the second season of haters back off come out

text: Haters Back Off

text: Background[edit]

text: Miranda Sings[edit]

text: Since 2008, Colleen Ballinger has posted videos as her comically talentless, narcissistic and quirky character, Miranda Sings, primarily on the YouTube channel Miranda Sings.[14] The character is a satire of bad, but egotistical, performers who film themselves singing as a form of self-promotion.[15] Miranda is portrayed as a home-schooled young woman who is eccentric and infantilized, narcissistically believes that she was born famous, and is obsessed with show business fame.[16][17] Miranda uses spoonerisms and malapropisms, is irritable, ludicrously self-absorbed and self-righteous, socially awkward, and has a defiant, arrogant attitude.[18][19] She responds to people who offer criticism with the catchphrase, "Haters back off!"[20][21]

text: In March 2009, Ballinger uploaded a Miranda video called "Free Voice Lesson", full of awful singing advice, that quickly became her first viral sensation.[22][23] This led to requests for Ballinger to perform live as Miranda,[24] and she later began to tour worldwide.[25] The Miranda Sings YouTube channel has received more than 1 billion views and has more than 8 million subscribers,[26][6] while Ballinger's personal YouTube channel, PsychoSoprano, has more than 900 million views and 5 million subscribers.[27] Miranda has appeared in character on television shows[28] and Ballinger released a 2015 book, Selp-Helf, written in Miranda's voice,[29] that ranked No. 1 on The New York Times Best Seller list for Advice, How-To & Miscellaneous.[30]

text: Genesis of, and anticipation for, the series[edit]

text: Ballinger told interviewers that she and her brother Chris began to develop the idea for the show about five or six years before it premiered. At first they considered a film treatment but later decided on a television series format. Ballinger chose Netflix over HBO to produce Haters Back Off because she felt that Netflix understood and was enthusiastic about the character and its online origin and fanbase.[5][31] Comparing the show to Christopher Guest's Waiting for Guffman, showrunner Perry Rein said: "This is the first time we’ve done a show about a really bad dancer and singer. [It has] characters that take themselves very seriously in their very small worlds."[5]

text: On YouTube, Miranda has always had an offstage relationship with her mother and uncle, and Ballinger long had the idea for Miranda's best friend, Patrick. Ballinger said that she wanted to use the longer format of the series to expose Miranda's vulnerability and make her believable; to explain the source of the insecurities that make her so rude and eccentric. Emily, Miranda’s sister, is a new character. Ballinger said that her brother, Chris, helped Francesca Reale to create the character.[32] Emily is the only normal person in Miranda's family, but they treat her as the odd one, like Marilyn in The Munsters.[33] The series expands Miranda's world seen in YouTube. Miranda represents an "extreme version of what the average gawky teenage girl may be feeling."[34]

text: /Film mused: "Haters Back Off seems like a smart move for Netflix. [A] streaming content provider seems like a natural fit. Her built-in audience is already used to watching original content online".[35] TechCrunch commented: "[T]he rise of YouTube-fueled online influencers has been breathtaking ... building big audiences beyond the reach, knowledge and control of traditional entertainment gatekeepers, including the networks. ... Netflix can ... leverage the audiences of these online stars, and their marketing reach, to drive the fans to new properties ... online, where their fans already routinely seek entertainment".[36] In September 2016, the series was included in The Wall Street Journal's list of "The 6 Best New Things to Stream in October".[37] Bustle.com listed "11 Reasons You Should Watch ... Haters Back Off", writing that "Miranda has become emblematic of a new kind [of] star-seeker in the digital age: a youngster who decides that waiting for a fame-making opportunity simply won't do and that in order to become visible (and ostensibly beloved), you have to create the opportunities for visibility yourself."[38]

text: Cast[edit]

text: Main[edit]

text:
Colleen Ballinger as Miranda Sings, a talentless, egotistical, quirky, home-schooled young "want-to-be star".[39]
Angela Kinsey as Bethany, Miranda's hypochondriac mother[40]
Steve Little as Jim, Miranda's enabling uncle and manager[39][40]
Erik Stocklin as Patrick Mooney, Miranda's best friend and neighbor[41][42]
Francesca Reale as Emily, Miranda's exasperated, voice-of-reason-and-normality sister[4]
Matt Besser as Miranda's father (Season 2)[12]

text: Recurring[edit]

text:
Chaz Lamar Shepherd as Keith, a local pastor[4] (Season 1)
Dylan Playfair as Owen Trent, the church choir's dreamy but narcissistic guitarist (Season 1)
Harvey Guillen as Harvey, the manager and son of the owner of the fish shop (Season 1)
Lindsay Navarro as Kleigh (Season 1)
Rachelle Gillis as April (Season 1)

text: Guest stars[edit]

text:
Ben Stiller as himself (Season 1)
John Early as Maureen, the Mattress Queen (Season 1)

text: Production and promotion[edit]

text: Season 1 of Haters Back Off began filming in April 2016 in and around Port Coquitlam, British Columbia, near Vancouver,[2][43] which substitutes, in the series, for Miranda's hometown, Tacoma, Washington.[44] Filming on Season 1 wrapped on June 3, 2016.[45] Ballinger began promotions for season 1 in January 2016 with a comic YouTube video announcement.[46] Miranda was featured on the cover of Variety, and in a feature article about the show, in June 2016.[5] Ballinger also promoted the show on her social media, including with an original song about it performed by Miranda.[47] On September 1, 2016, Netflix released the first production stills from Season 1.[48] On September 21, the show released its first of a series of teasers.[49][50] Ballinger appeared on The Tonight Show on October 14, 2016, the release date, to promote the series.[51]

text: Season 2 filmed in and around Vancouver from April until June 5, 2017.[52] Ballinger began promotions for Season 2 in August 2017 with an appearance on Live with Kelly and Ryan.[53] Ballinger announced the release date of Season 2 in character as Miranda on the Miranda Sings YouTube channel on September 11, 2017.[54] On the same date, she released a new original song on Miranda's YouTube channel to promote the season.[55] On October 10, 2017, Netflix released the official trailer for Season 2.[13]

text: Series overview[edit]

text:
Season
Episodes
Originally released

1
8
October 14, 2016 (2016-10-14)

2
8[11]
October 20, 2017 (2017-10-20)

text: Episodes[edit]

text: Season 1 (2016)[edit]

text:
No.
Title
Directed by
Written by
Original release date

1
"Uploding my Fist Video"
Andrew Gaynord
Story by : Colleen Ballinger & Chris Ballinger
Teleplay by : Colleen Ballinger, Gigi McCreery & Perry Rein
October 14, 2016 (2016-10-14)

Miranda and her adoring uncle Jim upload her first video, a tone-deaf cover of "Defying Gravity". This launches Jim's 5-phase plan for fame. Miranda is home-schooled by her single mom, Bethany, a hypochondriac who works as a grocery store cashier. Bethany indulges Miranda. In their cluttered little Tacoma, Washington, house, Miranda is alarmed to receive her first YouTube death threat. Miranda's best friend, Patrick, is smitten with her. He sells popsicles and gives her one every day from his bicycle cooler. Jim gets Miranda into a TV ad for his employer, a fish store, but the fish die under the hot lights set up for filming the ad. Patrick almost kills the store's owner by mistake before Miranda's exasperated sister Emily confesses to anonymously posting the death threat. Miranda is devastated by the betrayal but vows to keep seeking YouTube fame. Emily and Miranda agree to pretend in public that they are not sisters. Jim is fired from the fish store and decides to become Miranda's full-time manager. Miranda's video accumulates dozens of views, but more hateful comments have arrived.

2
"Preeching 2 the Chior"
Andrew Gaynord
Justin Varava
October 14, 2016 (2016-10-14)

Miranda uploads a tearful video titled "I Quit!". Jim begs her not to give up: after his high school ribbon dancing color guard performance went badly awry, he gave up his passion and lives a life of regret. At church, Bethany is attracted to the pastor, Keith; Miranda likes the choir's dreamy guitarist, Owen, and decides to join the choir. She is horrible to the choir, and they ask Keith to dismiss her. Patrick tries to console her, but she misunderstands his advice and vows to make Owen fall in love with her. Jim sells his car for $500. At the church singles night, the choir is performing. Miranda invades the stage and starts to sing a racy love song to Owen. When challenged, Miranda calls everyone a "hater". Pastor Keith asks Owen to remove Miranda, and Owen abandons her outside the church. Bethany advises Miranda not to let anyone stop her. Jim gives the $500 to the fish store manager to get his job back, but Miranda arrives and says that she is going back on the internet. Jim eagerly quits his job!

3
"Netwerking at the Nursing Home"
Andrew Gaynord
Russ Woody
October 14, 2016 (2016-10-14)

Miranda uploads her cover of "Respect". Emily asks Miranda to sing for their aunt Moira, who is in a nursing home suffering from dementia. Miranda and Jim realize that, if Moira dies, Miranda might "get her stuff". Patrick rings the bell on his bicycle to give Miranda her daily popsicle. Bethany flirts with smooth-talking pastor Keith at the grocery store. At the nursing home, Miranda abandons Moira to meet Bob Hamburg, an old movie director spotted by Jim, hoping for an audition. Meanwhile, Patrick confronts Owen and finds out that Owen has no interest in Miranda. Miranda sneaks into the nursing home, where her singing kills Bob. Bob's nephew (Ben Stiller) asks Miranda to speak at the funeral, as she was "closest to" Bob when he died. Stiller notes that he is "in the industry", but Miranda doesn't want an "industrial job". At the funeral, instead of eulogizing Bob, Miranda begins to sing. Emily interrupts, and Miranda and Jim call Emily a jealous hater. Miranda uploads a new video, singing "Danny Boy".

4
"Rod Trip With My Uncle"
Todd Rohal
Colleen Ballinger & Chris Ballinger
October 14, 2016 (2016-10-14)

Pastor Keith, at Miranda's house, announces that he has been dating Bethany since the funeral. Miranda is angry, but Keith offers to get her a singing gig at the prestigious Thea Foss Theatre. Jim is jealous and says he has a better gig at a venue in Seattle. Although Jim has no luck booking a theatre, he sets off with Miranda in Bethany's minivan, with Patrick as their roadie. Miranda chooses a stage name: "Miranda Sings"! As the van gets impounded (Patrick had painted a billboard of Miranda on it that covers the windows), Jim sees a Karaoke bar and says that the gig is there. On the elevated stage, Miranda is worried the audience will see up her skirt, so Jim lends her his red sweatpants. Meanwhile, Emily grows suspicious that Keith has a fetish for sick people. Patrick phones Emily to ask for a ride home. Miranda sings "All That Jazz" at the Karaoke competition, but Patrick's bubble machine makes the stage slippery, and Miranda struggles to finish the number. Emily, Bethany and Keith arrive to see the debacle. Keith proposes to Bethany, but she says no: her family needs her more. Miranda, Jim and Patrick win the competition as a comedy trio, but Miranda is angry: she is a solo singing act! Jim happily picks up the $100 prize.

5
"Staring in a Musicall"
Todd Rohal
Gigi McCreery & Perry Rein
October 14, 2016 (2016-10-14)

Bethany edits Miranda's dance video cover of "Genie in a Bottle" and suggests that they do a home production of Annie. Jim forcefully takes over as director, planning to tape the performance for Broadway producers. Finding that Daddy Warbucks is Annie's love interest in this version of the musical, the actor cast in the part quits in disgust. Patrick takes the role, as he has memorized all of Warbucks' lines; he looks forward to his stage kiss with Miranda as Annie. Jim has a toilet in his bedroom, and Bethany calls a plumber, who determines that it has leaked raw sewage into the back yard, where the cast is rehearsing. The musical is shut down. Emily is embarrassed when her friend Kleigh discovers that Emily has been lying about not being Miranda's sister.

6
"Becuming a Magichin"
Andrew Gaynord
Justin Varava & Russ Woody
October 14, 2016 (2016-10-14)

Miranda makes a video tutorial: "Free Voice Lesson". Jim thinks it will be a hit, but Miranda refuses to upload it, as it gives away her vocal secrets. Patrick is excited about his upcoming audition at a magic club. Miranda is impatient to get famous, so Patrick offers to teach her some magic and let her audition in his place. Miranda a spectacular trick: Patrick's magic sword cabinet! He will be her assistant. Miranda notices Patrick's romantic artwork made from her many popsicle sticks. Emily is still depressed; she paints alone in the garage. Jim, unable to occupy his room until the plumbing is fixed, moves in with Bethany, to her disgust. Bethany wanders backstage at the magic auditions, but her presence there would disqualify Miranda. Before Bethany can flee, stagehands come, and she hides in the magic cabinet, which they wheel onstage. Patrick is surprised to meet Bethany inside the cabinet. Miranda sticks in the swords, and Patrick helps Bethany avoid getting stabbed, until Miranda goes off script, and both Bethany and Patrick are wounded. At the hospital, Bethany's doctors find a kidney abnormality, as Miranda watches over Patrick.

7
"Starr off the Parade"
Andrew Gaynord
Gigi McCreery & Perry Rein
October 14, 2016 (2016-10-14)

Miranda uploads a cover of "Love Shack". Patrick finally asks Miranda on a date, but she says she would only marry a famous person, since she is famous. The doctors tell Bethany that her kidneys are failing. Emily wants to move away to an art school. Jim tries to get Miranda on the Grand Marshal's float in the upcoming town parade. When rebuffed, Jim decides to form a color guard of home schoolers to march with Miranda in the parade, with Jim as ribbon dancer. Patrick builds the "home schooled" float around his ice cream bicycle; it looks like a huge Uncle Jim pony. Miranda rides aboard in a pink cowboy hat as Jim's color guard performs beautifully, but his pyrotechnics light the float on fire just as Miranda kisses Patrick inside it and agrees to go on a date with him. At her art school admission panel, Emily discovers that Miranda has altered Emily's portfolio by gluing macaroni, felt and sparkles to her artworks; they are all ruined.

8
"i'm famous"
Andrew Gaynord
Colleen Ballinger & Chris Ballinger
October 14, 2016 (2016-10-14)

Miranda forbids Jim to post the "Free Voice Lesson" video. She and Patrick plan to go on a date. Owen invites them to his CD release party at the Thea Foss Theatre; Miranda is angry that Jim has not booked her there. She rushes to the theatre, where Owen asks her to perform in his show right before he announces "a big surprise". Bethany's kidney disease is worsening. As Miranda ruined her art school admission, Emily leaves home to live with their father. Owen asks Miranda to hold a diamond ring for his big surprise. Miranda thinks that he is proposing to her and puts on the ring; she coldly cancels the elaborate date that Patrick has planned for them. Jim posts the "Free Voice Lesson" video to YouTube; Miranda fires him. She gets on stage to sing "I Will Always Love You" to Owen, who cuts her off, saying it is a joke. Owen proposes to April, pulling the ring off of Miranda's finger. The audience starts laughing at everything Miranda says. She asks: "Why is it funny that someone would love me?" and they fall silent. Miranda attacks Owen and April to get the ring but is pulled away and forced out into the pouring rain by security. Miranda has treated everyone so badly that no one will take her calls. Arriving drenched at home, she yells at Bethany, who explains that she failed to attend because of her kidney medication. Bethany reveals that she needs a kidney donor or she will die. She leaves Miranda all alone in the house. Miranda is about to delete "Free Voice Lesson", but sees that it has over 100,000 views and many positive comments. She yells "Uncle Jim, it worked!", but no one is there. More views accumulate as she experiences her moment of greatest loneliness. Just then, Miranda hears the bell of Patrick's bike and looks up hopefully.

text: Season 2 (2017)[edit]

text: The series has been renewed for a second season of 8 episodes, bringing the total number of episodes to 16.[11]

text:
No.
Title
Directed by
Written by
Original release date

9
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

10
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

11
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

12
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

13
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

14
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

15
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

16
TBA
TBA
TBA
October 20, 2017 (2017-10-20)

text: Reception[edit]

text: The first season of Haters Back Off received mixed reviews from critics. On Rotten Tomatoes, the season has a rating of 47%, based on 14 reviews, with an average rating of 5.5/10. The site's critical consensus reads, "Haters Back Off is bizarre, painful, and often times excruciatingly funny – yet the appeal of the YouTube transport doesn't quite carry over in the longer television format."[56] On Metacritic, the season has a score of 54 out of 100, based on 9 critics, indicating "mixed or average reviews".[57] The show won the "Best Comedy" award at the 2016 CelebMix Awards.[58]

text: Positive reviews of Haters Back Off include Robert Lloyd's in the Los Angeles Times, who observed that, unlike in Miranda’s YouTube videos, the character's actions in the TV series have consequences and affect the other characters and their feelings. Lloyd thought that the series succeeds in "shaping a funny idea into a semblance of life". He praised the performances, especially Kinsey's.[59] The Guardian printed two positive reviews: Brian Moylan called the series a "hilarious transfer to Netflix. ... Ballinger gets at something that is not only a cultural critique but often hits on the fragility of egos and everyone’s need for acceptance."[60] In their other review, Stuart Heritage wrote: "It's a uniformly singular sitcom about the effects of fame, and frequently a very funny one. ... [I]t is great, once you’ve attuned yourself to its quirks".[61] Melanie McFarland, on NPR, compared Miranda's world with Pee-wee Herman's, saying that both are "perversely funny, cartoonish worlds that also manage to be weirdly innocent. 'There's just that sly element of wrongness about it that makes it oh so right.'"[34] Daniel D'Addario wrote in Time magazine that the series "is imperfect, but it's also more than it needed to be. ... Ballinger examine[s] what the obsession with having fans papers over and the new problems it creates."[62] Paste magazine ranked Haters Back Off as the 9th "best new Netflix Original Series of 2016".[63]

text: TheWrap's Michael E. Ross called the series an "antic, sometimes wise, often laugh-out-loud funny case of art imitating life imitating art", noting that "there are times ... when the veneer of ego is stripped away, and we discover the shy, insecure young woman behind the bluster. Haters reflects a hearty sense of humor about the genesis of online celebrity. ... [W]hat resonates ... is Miranda’s underlying humanity, her basic drive to be recognized, to stand apart from the crowd. And we can all relate to the pain of rejection".[64] Jasef Wisener of TVOvermind.com gave the series 3.8 stars out of 5. He was favorably impressed by the character development and the performances, especially Ballinger's and Reale's. He also liked its structure and musical score, but felt that the exposition was sometimes bogged down in the early episodes by its explanation of details and sometimes panders to Miranda's established internet audience; he felt that the series improves in the later episodes. He disliked the sexual innuendos and found Miranda's relationship with Uncle Jim uncomfortable, although these are elements carried over from Miranda's YouTube videos.[4] The A.V. Club's Danette Chavez commented that Ballinger's "portrayal of Miranda is multidimensional in spite of the character's single-mindedness. ... Haters fleshes out the environment that would spawn such an egotistical personality. ... [L]aughs are as consistently delivered" with zany comedy, although the "domestic strife and even anguish" makes the series nearly a dramedy. But she felt that "sometimes the foreshadowing is just a little too foreboding. ... the tonal shifts don’t always jibe."[40]

text: In a mixed review for New York magazine's Vulture site, Jen Chaney judged that "not everything in Haters Back Off! works. ... If you find Miranda Sings irritating after watching a two-minute YouTube clip, you should find something else to put in your queue. But ... fans ... who have a reasonable amount of patience will likely find some redeeming qualities to latch onto, especially as the episodes progress. ... Miranda is a purposely maddening character. But Ballinger commits to her so fully and with such specific physicality ... that she's often mesmerizing to watch. ... [But] maybe Miranda Sings is better in shorter doses."[65] Similarly, for The New York Times, James Poniewozik wrote that:

text: Like Miranda’s performances, Haters can be terrible and transfixing at the same time. ... Ballinger commits to Miranda's hunger and histrionics. ... There's a deeper pathos to Miranda's situation, but the season doesn't delve deeply into that until late, by which time haters will have long since backed off. ... There's a lot in Haters Back Off! to gratify Ms. Ballinger's YouTube fan base. ... Beyond the winces, there's something human in its comedy of internet thirst: the insatiable drive to put a piece of oneself out into the world and hit refresh, refresh, refresh.[66]

text: Brian Lowry, writing for CNN, had a mostly negative reaction. While he felt that while the series' "critique of a fame-obsessed culture certainly has merit", and that the later episodes "reward patience", the show was too "cartoon-like", and "there's a sense that the series is stretched beyond what it has to offer."[67] Keith Uhlich, in The Hollywood Reporter, found the gags funny, but he concluded that although Miranda is "an acidic critique of the very celebrity strivers who make up the majority of the YouTube community", it is more effective "in short bursts". In "an eight-episode Netflix series ... the lampoon loses its edge". He also thought that much of the pathos in the series is "unearned, unconvincing" and the characters are "shallow vessels freighted down by contrived plot complications . ... And there's more than a bit of that vainglorious YouTubers' entitlement in where Haters ultimately ends up, the satire finally curdling into smugness."[68] Sonia Saraiya of Variety did not think that the series has "the same organic appeal as Ballinger’s bizarre, pastiche-y videos. ... Miranda lacks some of the innocent naivete that makes her character work on YouTube. ... Miranda’s behavior ... could be raucously hilarious [for some viewers], an example of theater-geek self-obsession run amok. For me, anyway, Miranda’s obsessions and absorptions ... prove to be more tragic than hilarious."[69] Rob Lowman of the Los Angeles Daily News wrote: "The series seems to want to exist somewhere between a Pee-wee Herman world, where Miranda exists within her own reality, and Waiting for Guffman or other parodies of self-important clueless people. It doesn’t succeed as either, nor on its own terms.[39]

text: The show debuted as the 2nd most popular digital original series in the US for the week of October 14–20, 2016.[70]


document_title: Electrocardiography

question_text: where are leads 1 2 and 3 placed

text: Electrocardiography

text: History[edit]

text: The etymology of the word is derived from the Greek electro, because it is related to electrical activity, kardio, Greek for heart, and graph, a Greek root meaning "to write".

text: Alexander Muirhead is reported to have attached wires to a feverish patient's wrist to obtain a record of the patient's heartbeat in 1872 at St Bartholomew's Hospital.[7] Another early pioneer was Augustus Waller, of St Mary's Hospital in London.[8] His electrocardiograph machine consisted of a Lippmann capillary electrometer fixed to a projector. The trace from the heartbeat was projected onto a photographic plate that was itself fixed to a toy train. This allowed a heartbeat to be recorded in real time.

text: An initial breakthrough came when Willem Einthoven, working in Leiden, the Netherlands, used the string galvanometer (the first practical electrocardiograph) he invented in 1901.[9] This device was much more sensitive than both the capillary electrometer Waller used and the string galvanometer that had been invented separately in 1897 by the French engineer Clément Ader.[10] Einthoven had previously, in 1895, assigned the letters P, Q, R, S, and T to the deflections in the theoretical waveform he created using equations which corrected the actual waveform obtained by the capillary electrometer to compensate for the imprecision of that instrument. Using letters different from A, B, C, and D (the letters used for the capillary electrometer's waveform) facilitated comparison when the uncorrected and corrected lines were drawn on the same graph.[11] Einthoven probably chose the initial letter P to follow the example set by Descartes in geometry.[11] When a more precise waveform was obtained using the string galvanometer, which matched the corrected capillary electrometer waveform, he continued to use the letters P, Q, R, S, and T,[11] and these letters are still in use today. Einthoven also described the electrocardiographic features of a number of cardiovascular disorders. In 1924, he was awarded the Nobel Prize in Medicine for his discovery.[12]

text: By 1927, General Electric had developed a portable apparatus that could produce electrocardiograms without the use of the string galvanometer. This device instead combined amplifier tubes similar to those used in a radio with an internal lamp and a moving mirror that directed the tracing of the electric pulses onto film.[13]

text: In 1937, Taro Takemi invented a new portable electrocardiograph machine.[14]

text: Though the basic principles of that era are still in use today, many advances in electrocardiography have been made over the years. Instrumentation has evolved from a cumbersome laboratory apparatus to compact electronic systems that often include computerized interpretation of the electrocardiogram.[15]

text: Medical uses[edit]

text: The overall goal of performing electrocardiography is to obtain information about the structure and function of the heart. Medical uses for this information are varied and generally relate to having a need for knowledge of the structure and/or function. Some indications for performing electrocardiography include:

text:
Suspected myocardial infarction (heart attack) or chest pain
Suspected pulmonary embolism or shortness of breath
A third heart sound, fourth heart sound, a cardiac murmur[16] or other findings to suggest structural heart disease
Perceived arrhythmia either by pulse or palpitations
Monitoring of known cardiac dysrhythmias
Fainting or collapse[16]
Seizures[16]
Monitoring the effects of a heart medication (e.g. drug-induced QT prolongation)
Assessing severity of electrolyte abnormalities, such as hyperkalemia
Hypertrophic cardiomyopathy screening in adolescents as part of a sports physical out of concern for sudden cardiac death (varies by country)
Perioperative monitoring in which any form of anesthesia is involved (e.g. monitored anesthesia care, general anesthesia); typically both intraoperative and postoperative
As a part of a pre-operative assessment some time before a surgical procedure (especially for those with known cardiovascular disease or who are undergoing invasive or cardiac, vascular or pulmonary procedures, or who will receive general anesthesia)
Cardiac stress testing
Computed tomography angiography (CTA) and Magnetic resonance angiography (MRA) of the heart (ECG is used to "gate" the scanning so that the anatomical position of the heart is steady)
Biotelemetry of patients for any of the above reasons and such monitoring can include internal and external defibrillators and pacemakers

text: The United States Preventive Services Task Force does not recommend electrocardiography for routine screening procedure in patients without symptoms and those at low risk for coronary heart disease.[17][18] This is because an ECG may falsely indicate the existence of a problem, leading to misdiagnosis, the recommendation of invasive procedures, or overtreatment. However, persons employed in certain critical occupations, such as aircraft pilots,[19] may be required to have an ECG as part of their routine health evaluations.

text: Continuous ECG monitoring is used to monitor critically ill patients, patients undergoing general anesthesia,[16] and patients who have an infrequently occurring cardiac dysrhythmia that would be unlikely to be seen on a conventional ten-second ECG.

text: Performing a 12-lead ECG in the United States is commonly performed by specialized technicians that may be certified electrocardiogram technicians. ECG interpretation is a component of many healthcare fields (nurses and physicians and cardiac surgeons being the most obvious), but anyone trained to interpret an ECG is free to do so. However, "official" interpretation is performed by a cardiologist. Certain fields such as anesthesia utilize continuous ECG monitoring, and knowledge of interpreting ECGs is crucial to their jobs.

text: One additional form of electrocardiography is used in clinical cardiac electrophysiology in which a catheter is used to measure the electrical activity. The catheter is inserted through the femoral vein and can have several electrodes along its length to record the direction of electrical activity from within the heart.

text: Electrocardiographs[edit]

text: An electrocardiograph is a machine that is used to perform electrocardiography, and produces the electrocardiogram. The first electrocardiographs are discussed above and are electrically primitive compared to today's machines.

text: The fundamental component to electrocardiograph is the Instrumentation amplifier, which is responsible for taking the voltage difference between leads (see below) and amplifying the signal. ECG voltages measured across the body are on the order of hundreds of microvolts up to 1 millivolt (the small square on a standard ECG is 100 microvolts). This low voltage necessitates a low noise circuit and instrumentation amplifiers are key.

text: Early electrocardiographs were constructed with analog electronics and the signal could drive a motor to print the signal on paper. Today, electrocardiographs use analog-to-digital converters to convert to a digital signal that can then be manipulated with digital electronics. This permits digital recording of ECGs and use on computers.

text: There are other components to the electrocardiograph:[20]

text:
Safety features that include voltage protection for the patient and operator. Since the machines are powered by mains power, it is conceivable that either person could be subjected to voltage capable of causing death. Additionally, the heart is sensitive to the AC frequencies typically used for mains power (50 or 60 Hz).
Defibrillation protection. Any ECG used in healthcare may be attached to a person who requires defibrillation and the electrocardiograph needs to protect itself from this source of energy.
Electrostatic discharge is similar to defibrillation discharge and requires voltage protection up to 18,000 volts.
Additionally circuitry called the right leg driver can be used to reduce common-mode interference (typically the 50/60 Hz mains power).

text: The typical design for a portable electrocardiograph is a combined unit that includes a screen, keyboard, and printer on a small wheeled cart. The unit connects to a long cable that branches to each lead and attaches to a conductive pad on the patient.

text: Lastly, the electrocardiograph may include a rhythm analysis algorithm that produces a computerized interpretation of the electrocardiogram. The results from these algorithms are considered "preliminary" until verified and/or modified by someone trained in interpreting electrocardiograms. Included in this analysis is computation of common parameters that include PR interval, QT duration, corrected QT (QTc) duration, PR axis, QRS axis, and more. Earlier designs recorded each lead sequentially but current designs employ circuits that can record all leads simultaneously. The former introduces problems in interpretation since there may be beat-to-beat changes in the rhythm, which makes it unwise to compare across beats.

text: Electrodes and leads[edit]

text: A "lead" is not the same as an "electrode". Whereas an electrode is a conductive pad in contact with the body that makes an electrical circuit with the electrocardiograph, a lead is a connector to an electrode. Since leads can share the same electrode, a standard 12-lead ECG happens to need only 10 electrodes (as listed in the table below).[citation needed]

text: A lead is slightly more abstract and is the source of measurement of a vector. For the limb leads, they are "bipolar" and are the comparison between two electrodes. For the precordial leads, they are "unipolar" and compared to a common lead (commonly the Wilson's central terminal), as described below.[22]

text: Leads are broken down into three sets: limb; augmented limb; and precordial or chest. The 12-lead ECG has a total of three limb leads and three augmented limb leads arranged like spokes of a wheel in the coronal plane (vertical), and six precordial leads or chest leads that lie on the perpendicular transverse plane (horizontal).[citation needed]

text: In medical settings, the term leads is also sometimes used to refer to the electrodes themselves, although this is not technically a correct usage of the term, which complicates the understanding of difference between the two.[citation needed]

text: The 10 electrodes in a 12-lead ECG are listed below.[23]

text:
Electrode name
Electrode placement

RA
On the right arm, avoiding thick muscle.

LA
In the same location where RA was placed, but on the left arm.

RL
On the right leg, lower end of medial aspect of calf muscle. (Avoid bony prominences)

LL
In the same location where RL was placed, but on the left leg.

V1
In the fourth intercostal space (between ribs 4 and 5) just to the right of the sternum (breastbone).

V2
In the fourth intercostal space (between ribs 4 and 5) just to the left of the sternum.

V3
Between leads V2 and V4.

V4
In the fifth intercostal space (between ribs 5 and 6) in the mid-clavicular line.

V5
Horizontally even with V4, in the left anterior axillary line.

V6
Horizontally even with V4 and V5 in the midaxillary line.

text: Two common electrodes used are a flat paper-thin sticker and a self-adhesive circular pad. The former are typically used in a single ECG recording while the latter are for continuous recordings as they stick longer. Each electrode consists of an electrically conductive electrolyte gel and a silver/silver chloride conductor.[24] The gel typically contains potassium chloride – sometimes silver chloride as well – to permit electron conduction from the skin to the wire and to the electrocardiogram.

text: The common lead, Wilson's central terminal VW, is produced by averaging the measurements from the electrodes RA, LA, and LL to give an average potential across the body:

text: In a 12-lead ECG, all leads except the limb leads are unipolar (aVR, aVL, aVF, V1, V2, V3, V4, V5, and V6). The measurement of a voltage requires two contacts and so, electrically, the unipolar leads are measured from the common lead (negative) and the unipolar lead (positive). This averaging for the common lead and the abstract unipolar lead concept makes for a more challenging understanding and is complicated by sloppy usage of "lead" and "electrode".

text: Limb leads[edit]

text: Leads I, II and III are called the limb leads. The electrodes that form these signals are located on the limbs – one on each arm and one on the left leg.[25][26][27] The limb leads form the points of what is known as Einthoven's triangle.[28]

text: Lead I is the voltage between the (positive) left arm (LA) electrode and right arm (RA) electrode:

text: Lead II is the voltage between the (positive) left leg (LL) electrode and the right arm (RA) electrode:

text: Lead III is the voltage between the (positive) left leg (LL) electrode and the left arm (LA) electrode:

text: Augmented limb leads[edit]

text: Leads aVR, aVL, and aVF are the augmented limb leads. They are derived from the same three electrodes as leads I, II, and III, but they use Goldberger's central terminal as their negative pole. Goldberger's central terminal is a combination of inputs from two limb electrodes, with a different combination for each augmented lead. It is referred to immediately below as "the negative pole".

text: Lead augmented vector right (aVR) has the positive electrode on the right arm. The negative pole is a combination of the left arm electrode and the left leg electrode:

text: Lead augmented vector left (aVL) has the positive electrode on the left arm. The negative pole is a combination of the right arm electrode and the left leg electrode:

text: Lead augmented vector foot (aVF) has the positive electrode on the left leg. The negative pole is a combination of the right arm electrode and the left arm electrode:

text: Together with leads I, II, and III, augmented limb leads aVR, aVL, and aVF form the basis of the hexaxial reference system, which is used to calculate the heart's electrical axis in the frontal plane.

text: Precordial leads[edit]

text: The precordial leads lie in the transverse (horizontal) plane, perpendicular to the other six leads. The six precordial electrodes act as the positive poles for the six corresponding precordial leads: (V1, V2, V3, V4, V5 and V6). Wilson's central terminal is used as the negative pole.

text: Specialized leads[edit]

text: Additional electrodes may rarely be placed to generate other leads for specific diagnostic purposes. Right-sided precordial leads may be used to better study pathology of the right ventricle or for dextrocardia (and are denoted with an R (e.g., V5R)). Posterior leads (V7 to V9) may be used to demonstrate the presence of a posterior myocardial infarction. A Lewis lead (requiring an electrode at the right sternal border in the second intercostal space) can be used to study pathological rhythms arising in the right atrium.

text: An esophogeal lead can be inserted to a part of the esophagus where the distance to the posterior wall of the left atrium is only approximately 5–6 mm (remaining constant in people of different age and weight).[29] An esophageal lead avails for a more accurate differentiation between certain cardiac arrhythmias, particularly atrial flutter, AV nodal reentrant tachycardia and orthodromic atrioventricular reentrant tachycardia.[30] It can also evaluate the risk in people with Wolff-Parkinson-White syndrome, as well as terminate supraventricular tachycardia caused by re-entry.[30]

text: An intracardiac electrogram (ICEG) is essentially an ECG with some added intracardiac leads (that is, inside the heart). The standard ECG leads (external leads) are I, II, III, aVL, V1, and V6. Two to four intracardiac leads are added via cardiac catheterization. The word "electrogram" (EGM) without further specification usually means an intracardiac electrogram.

text: Lead locations on an ECG report[edit]

text: A standard 12-lead ECG report (an electrocardiograph) shows a 2.5 second tracing of each of the twelve leads. The tracings are most commonly arranged in a grid of four columns and three rows. the first column is the limb leads (I, II, and III), the second column is the augmented limb leads (aVR, aVL, and aVF), and the last two columns are the precordial leads (V1-V6). Additionally, a rhythm strip may be included as a fourth or fifth row.

text: The timing across the page is continuous and not tracings of the 12 leads for the same time period. In other words, if the output were traced by needles on paper, each row would switch which leads as the paper is pulled under the needle. For example, the top row would first trace lead I, then switch to lead aVR, then switch to V1, and then switch to V4 and so none of these four tracings of the leads are from the same time period as they are traced in sequence through time.

text: Contiguity of leads[edit]

text: Each of the 12 ECG leads records the electrical activity of the heart from a different angle, and therefore align with different anatomical areas of the heart. Two leads that look at neighboring anatomical areas are said to be contiguous.

text:
Category
Leads
Activity

Inferior leads'
Leads II, III and aVF
Look at electrical activity from the vantage point of the inferior surface (diaphragmatic surface of heart)

Lateral leads
I, aVL, V5 and V6
Look at the electrical activity from the vantage point of the lateral wall of left ventricle

Septal leads
V1 and V2
Look at electrical activity from the vantage point of the septal surface of the heart (interventricular septum)

Anterior leads
V3 and V4
Look at electrical activity from the vantage point of the anterior wall of the right and left ventricles (Sternocostal surface of heart)

text: In addition, any two precordial leads next to one another are considered to be contiguous. For example, though V4 is an anterior lead and V5 is a lateral lead, they are contiguous because they are next to one another.

text: Electrophysiology[edit]

text: The formal study of the electrical conduction system of the heart is called cardiac electrophysiology (EP). An electrophysiology study involves a formal study of the conduction system and can be done for various reasons. During such a study, catheters are used to access the heart and some of these catheters include electrodes that can be placed anywhere in the heart to record the electrical activity from within the heart. Some catheters contain several electrodes and can record the propagation of electrical activity.

text: Interpretation[edit]

text: Interpretation of the ECG is fundamentally about understanding the electrical conduction system of the heart. Normal conduction starts and propagates in a predictable pattern, and deviation from this pattern can be a normal variation or be pathological. An ECG does not equate with mechanical pumping activity of the heart, for example, pulseless electrical activity produces an ECG that should pump blood but no pulses are felt (and constitutes a medical emergency and CPR should be performed). Ventricular fibrillation produces an ECG but is too dysfunctional to produce a life-sustaining cardiac output. Certain rhythms are known to have good cardiac output and some are known to have bad cardiac output. Ultimately, an echocardiogram or other anatomical imaging modality is useful in assessing the mechanical function of the heart.

text: Like all medical tests, what constitutes "normal" is based on population studies. The heart rate range of between 60 and 100 is considered normal since data shows this to be the usual resting heart rate.

text: Theory[edit]

text: Interpretation of the ECG is ultimately that of pattern recognition. In order to understand the patterns found, it is helpful to understand the theory of what ECGs represent. The theory is rooted in electromagnetics and boils down to the four following points:

text:
depolarization of the heart toward the positive electrode produces a positive deflection
depolarization of the heart away from the positive electrode produces a negative deflection
repolarization of the heart toward the positive electrode produces a negative deflection
repolarization of the heart away from the positive electrode produces a positive deflection

text: Thus, the overall direction of depolarization and repolarization produces a vector that produces positive or negative deflection on the ECG depending on which lead it points to. For example, depolarizing from right to left would produce a positive deflection in lead I because the two vectors point in the same direction. In contrast, that same depolarization would produce minimal deflection in V1 and V2 because the vectors are perpendicular and this phenomenon is called isoelectric.

text: Normal rhythm produces four entities – a P wave, a QRS complex, a T wave, and a U wave – that each have a fairly unique pattern.

text:
The P wave represents atrial depolarization.
The QRS complex represents ventricular depolarization.
The T wave represents ventricular repolarization.
The U wave represents papillary muscle repolarization.

text: However, the U wave is not typically seen and its absence is generally ignored. Changes in the structure of the heart and its surroundings (including blood composition) change the patterns of these four entities.

text: Electrocardiogram grid[edit]

text: ECGs are normally printed on a grid. The horizontal axis represents time and the vertical axis represents voltage. The standard values on this grid are shown in the adjacent image:

text:
A small box is 1 mm x 1 mm big and represents 0.1 mV x 0.04 seconds.
A large box is 5 mm x 5mm big and represents 0.5 mV x 0.2 seconds wide.

text: The "large" box is represented by a heavier line weight than the small boxes.

text: Not all aspects of an ECG rely on precise recordings or having a known scaling of amplitude or time. For example, determining if the tracing is a sinus rhythm only requires feature recognition and matching, and not measurement of amplitudes or times (i.e., the scale of the grids are irrelevant). An example to the contrary, the voltage requirements of left ventricular hypertrophy require knowing the grid scale.

text: Rate and rhythm[edit]

text: In a normal heart, the heart rate is the rate in which the sinoatrial node depolarizes as it is the source of depolarization of the heart. Heart rate, like other vital signs like blood pressure and respiratory rate, change with age. In adults, a normal heart rate is between 60 and 100 beats per minute (normocardic) where in children it is higher. A heart rate less than normal is called bradycardia (<60 in adults) and higher than normal is tachycardia (>100 in adults). A complication of this is when the atria and ventricles are not in synchrony and the "heart rate" must be specified as atrial or ventricular (e.g., the ventricular rate in ventricular fibrillation is 300–600 bpm, whereas the atrial rate can be normal (60–100) or faster (100–150)).

text: In normal resting hearts, the physiologic rhythm of the heart is normal sinus rhythm (NSR). Normal sinus rhythm produces the prototypical pattern of P wave, QRS complex, and T wave. Generally, deviation from normal sinus rhythm is considered a cardiac arrhythmia. Thus, the first question in interpreting an ECG is whether or not there is a sinus rhythm. A criterion for sinus rhythm is that P waves and QRS complexes appear 1-to-1, thus implying that the P wave causes the QRS complex.

text: Once sinus rhythm is established, or not, the second question is the rate. For a sinus rhythm this is either the rate of P waves or QRS complexes since they are 1-to-1. If the rate is too fast then it is sinus tachycardia and if it is too slow then it is sinus bradycardia.

text: If it is not a sinus rhythm, then determining the rhythm is necessary before proceeding with further interpretation. Some arrhythmias with characteristic findings:

text:
Absent P waves with "irregularly irregular" QRS complexes is the hallmark of atrial fibrillation
A "saw tooth" pattern with QRS complexes is the hallmark of atrial flutter
Sine wave pattern is the hallmark of ventricular flutter
Absent P waves with wide QRS complexes with fast rate is ventricular tachycardia

text: Determination of rate and rhythm is necessary in order to make sense of further interpretation.

text: Axis[edit]

text: The heart has several axes, but the most common by far is the axis of the QRS complex (references to "the axis" imply the QRS axis). Each axis can be computationally determined to result in a number representing degrees of deviation from zero, or it can be categorized into a few types.

text: The QRS axis is the general direction of the ventricular depolarization wavefront (or mean electrical vector) in the frontal plane. It is often sufficient to classify the axis as one of three types: normal, left deviated, or right deviated. Population data shows that a normal QRS axis is from −30° to 105°, with 0° being along lead I and positive being inferior and negative being superior (best understood graphically as the hexaxial reference system).[31] Beyond +105° is right axis deviation and beyond −30° is left axis deviation (the third quadrant of −90° to −180° is very rare and is an indeterminate axis). A shortcut for determining if the QRS axis is normal is if the QRS complex is mostly positive in lead I and lead II (or lead I and aVF if +90° is the upper limit of normal).

text: The normal QRS axis is generally down and to the left, following the anatomical orientation of the heart within the chest. An abnormal axis suggests a change in the physical shape and orientation of the heart or a defect in its conduction system that causes the ventricles to depolarize in an abnormal way.

text:
Classification
Angle
Notes

Normal
−30° to 105°
Normal

Left axis deviation
−30° to −90°
May indicate left ventricular hypertrophy, left anterior fascicular block, or an old inferior q-wave myocardial infarction

Right axis deviation
+105° to +180°
May indicate right ventricular hypertrophy, left posterior fascicular block, or an old lateral q-wave myocardial infarction

Indeterminate axis
+180° to −90°
Rarely seen; considered an 'electrical no-man's land'

text: The extent of a normal axis can be +90° or 105° depending on the source.

text: Amplitudes and intervals[edit]

text: All of the waves on an ECG tracing and the intervals between them have a predictable time duration, a range of acceptable amplitudes (voltages), and a typical morphology. Any deviation from the normal tracing is potentially pathological and therefore of clinical significance.

text: For ease of measuring the amplitudes and intervals, an ECG is printed on graph paper at a standard scale: each 1 mm (one small box on the standard ECG paper) represents 40 milliseconds of time on the x-axis, and 0.1 millivolts on the y-axis.

text:
Feature
Description
Pathology
Duration

P wave
The p-wave represents depolarization of the atria. Atrial depolarization spreads from the SA node towards the AV node, and from the right atrium to the left atrium.
The p-wave is typically upright in most leads except for aVR; an unusual p-wave axis (inverted in other leads) can indicate an ectopic atrial pacemaker. If the p wave is of unusually long duration, it may represent atrial enlargement. Typically a large right atrium gives a tall, peaked p-wave while a large left atrium gives a two-humped bifid p-wave.
<80 ms

PR interval
The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. This interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node.
A PR interval shorter than 120 ms suggests that the electrical impulse is bypassing the AV node, as in Wolf-Parkinson-White syndrome. A PR interval consistently longer than 200 ms diagnoses first degree atrioventricular block. The PR segment (the portion of the tracing after the p-wave and before the QRS complex) is typically completely flat, but may be depressed in pericarditis.
120 to 200 ms

QRS complex
The QRS complex represents the rapid depolarization of the right and left ventricles. The ventricles have a large muscle mass compared to the atria, so the QRS complex usually has a much larger amplitude than the P-wave.
If the QRS complex is wide (longer than 120 ms) it suggests disruption of the heart's conduction system, such as in LBBB, RBBB, or ventricular rhythms such as ventricular tachycardia. Metabolic issues such as severe hyperkalemia, or TCA overdose can also widen the QRS complex. An unusually tall QRS complex may represent left ventricular hypertrophy while a very low-amplitude QRS complex may represent a pericardial effusion or infiltrative myocardial disease.
80 to 100 ms

J-point
The J-point is the point at which the QRS complex finishes and the ST segment begins.
The J point may be elevated as a normal variant. The appearance of a separate J wave or Osborn wave at the J point is pathognomonic of hypothermia or hypercalcemia.[32]

ST segment
The ST segment connects the QRS complex and the T wave; it represents the period when the ventricles are depolarized.
It is usually isoelectric, but may be depressed or elevated with myocardial infarction or ischemia. ST depression can also be caused by LVH or digoxin. ST elevation can also be caused by pericarditis, Brugada syndrome, or can be a normal variant (J-point elevation).

T wave
The T wave represents the repolarization of the ventricles. It is generally upright in all leads except aVR and lead V1.
Inverted T waves can be a sign of myocardial ischemia, LVH, high intracranial pressure, or metabolic abnormalities. Peaked T waves can be a sign of hyperkalemia or very early myocardial infarction.
160 ms

Corrected QT interval (QTc)
The QT interval is measured from the beginning of the QRS complex to the end of the T wave. Acceptable ranges vary with heart rate, so it must be corrected to the QTc by dividing by the square root of the RR interval.
A prolonged QTc interval is a risk factor for ventricular tachyarrhythmias and sudden death. Long QT can arise as a genetic syndrome, or as a side effect of certain medications. An unusually short QTc can be seen in severe hypercalcemia.
<440 ms

U wave
The U wave is hypothesized to be caused by the repolarization of the interventricular septum. It normally has a low amplitude, and even more often is completely absent.
If the U wave is very prominent, suspect hypokalemia, hypercalcemia or hyperthyroidism.[33]

text: Ischemia and infarction[edit]

text: Ischemia or non-ST elevation myocardial infarctions may manifest as ST depression or inversion of T waves. It may also affect the high frequency band of the QRS.

text: ST elevation myocardial infarctions have different characteristic ECG findings based on the amount of time elapsed since the MI first occurred. The earliest sign is hyperacute T waves, peaked T-waves due to local hyperkalemia in ischemic myocardium. This then progresses over a period of minutes to elevations of the ST segment by at least 1 mm. Over a period of hours, a pathologic Q wave may appear and the T wave will invert. Over a period of days the ST elevation will resolve. Pathologic q waves generally will remain permanently.[34]

text: The coronary artery that has been occluded can be identified in an ST-elevation myocardial infarction based on the location of ST elevation. The LAD supplies the anterior wall of the heart, and therefore causes ST elevations in anterior leads (V1 and V2). The LCx supplies the lateral aspect of the heart and therefore causes ST elevations in lateral leads (I, aVL and V6). The RCA usually supplies the inferior aspect of the heart, and therefore causes ST elevations in inferior leads (II, III and aVF).

text: Artifacts[edit]

text: An ECG tracing is affected by patient motion. Some rhythmic motions (such as shivering or tremors) can create the illusion of cardiac dysrhythmia.[35] Artifacts are distorted signals caused by a secondary internal or external sources, such as muscle movement or interference from an electrical device.[36][37]

text: Distortion poses significant challenges to healthcare providers,[36] who employ various techniques[38] and strategies to safely recognize[39] these false signals.[medical citation needed] Accurately separating the ECG artifact from the true ECG signal can have a significant impact on patient outcomes and legal liabilities.[40][unreliable medical source?]

text: Improper lead placement (for example, reversing two of the limb leads) has been estimated to occur in 0.4% to 4% of all ECG recordings,[41] and has resulted in improper diagnosis and treatment including unnecessary use of thrombolytic therapy.[42][43]

text: Diagnosis[edit]

text: Numerous diagnoses and findings can be made based upon electrocardiography, and many are discussed above. Overall, the diagnoses are made based on the patterns. For example, an "irregularly irregular" QRS complex without P waves is the hallmark of atrial fibrillation; however, other findings can be present as well, such as a bundle branch block that alters the shape of the QRS complexes. ECGs can be interpreted in isolation but should be applied – like all diagnostic tests – in the context of the patient. For example, an observation of peaked T waves is not sufficient to diagnose hyperkalemia; such a diagnosis should be verified by measuring the blood potassium level. Conversely, a discovery of hyperkalemia should be followed by an ECG for manifestations such as peaked T waves, widened QRS complexes, and loss of P waves. The following is an organized list of possible ECG-based diagnoses.

text: Rhythm disturbances/arrhythmias:

text:
Atrial fibrillation & atrial flutter without rapid ventricular response
Premature atrial contraction (PACs) & Premature ventricular contraction (PVCs)
Sinus arrhythmia
Sinus bradycardia & sinus tachycardia
Sinus pause & sinoatrial arrest
Sick sinus syndrome: bradycardia-tachycardia syndrome
Supraventricular tachycardia

Atrial fibrillation (afib) with rapid ventricular response
Atrial flutter with rapid ventricular response
AV nodal reentrant tachycardia
Atrioventricular reentrant tachycardia
Junctional ectopic tachycardia
Atrial tachycardia

Ectopic atrial tachycardia (unicentric)
Multifocal atrial tachycardia
Paroxysmal atrial tachycardia

Sinoatrial nodal reentrant tachycardia

Torsades de pointes (polymorphic ventricular tachycardia)
Wide complex tachycardia

Ventricular flutter
Ventricular fibrillation
Ventricular tachycardia (monomorphic ventricular tachycardia)

Pre-excitation syndrome

Lown–Ganong–Levine syndrome
Wolff–Parkinson–White syndrome

J wave/Osborn wave

text: Heart block and conduction problems:

text:
Aberration
Sinoatrial block: first, second, and third-degree
AV node

First-degree AV block
Second-degree AV block (Mobitz I & II; Mobitz I aka Wenckebach)
Third-degree AV block/complete AV block

Right bundle

Incomplete right bundle branch block
Complete right bundle branch block (RBBB)

Left bundle

Complete left bundle branch block (LBBB)
Incomplete left bundle branch block
Left anterior fascicular block (LAFB)
Left posterior fascicular block (LPFB)
Bifascicular block (LAFB plus LPFB)
Trifascicular block (LAFP plus FPFB plus RBBB)

QT syndromes

Brugada syndrome
Short QT syndrome
Long QT syndromes, genetic and drug-induced

Right and left atrial abnormality

text: Electrolytes disturbances & intoxication:

text:
Digitalis intoxication
Calcium: hypocalcemia and hypercalcemia
Potassium: hypokalemia and hyperkalemia

text: Ischemia and infarction:

text:
Wellens' syndrome
ST elevation and ST depression
High Frequency QRS changes
Myocardial infarction (heart attack)

Non-Q wave myocardial infarction
NSTEMI
STEMI
Sgarbossa's criteria for ischemia with a LBBB

text: Structural:

text:
Acute pericarditis
Right and left ventricular hypertrophy
Right ventricular strain/S1Q3T3