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babli
Forum Guru Topics: 40 Posts: 424 |
An 18-year-old woman presents to the emergency department (ED) after experiencing syncope while backpacking 2 days ago. The patient states that she had been hiking with her friends up a steep hill, and the next thing that she remembered was waking up, lying on the trail. The event was not witnessed, and the patient does not recall any antecedent chest pain, shortness of breath, palpitations, or dizziness. She denies biting her tongue or having incontinence at the time of the event, but she remembers briefly feeling dazed. After a period of rest, she was able to finish the hike without further problems, but she comes into the office to get checked out just to be safe. She denies any past medical problems but does report experiencing a similar syncopal episode a few years ago again while she had been exerting herself. She has no recent history of illness or fever and does not report any subsequent chest pains, shortness of breath, or palpitations. She also denies recent dieting or use of any over-the-counter or illicit drugs. On examination, the patient has a normal temperature with a heart rate of 65 bpm and a blood pressure of 110/73 mm Hg. She is a well-appearing young woman in no acute distress. Findings on her head and neck examination are unremarkable. She has normal S1 and S2 heart sounds without any appreciated rubs, murmurs, or gallops. She has no jugular venous distention, and her lungs are clear bilaterally. Her abdomen is soft, without masses. She has no peripheral edema, and findings on neurologic examination are normal. Results of her laboratory work-up, including a complete blood count, chemistry panel, pregnancy test, and toxicology screen are normal. Her chest radiograph was likewise normal. An ECG is obtained (see Image). What is the diagnosis? Attached Files: 35q.jpg (57 KB, 43 downloads)
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
Prolonged QT Syndrome
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
Definition Prolonged QT syndrome, also known as long QT syndrome (LQTS), refers to a group of disorders that increase the risk for sudden death due to an abnormal heartbeat. Description Abnormal heartbeats (cardiac arrhythmias) are a primary cause of sudden death, especially in the young population. In the United States, an estimated 1 in 300,000 individuals per year die suddenly due to irregular heart rhythms. One of the better understood causes of these arrhythmias is LQTS. The QT of LQTS refers to an interval between two points (Q and T) on the common electrocardiogram (ECG, EKG) used to record the electrical activity of the heart. This electrical activity, in turn, is the result of small molecules (ions such as sodium and potassium) passing in and out of channels in the membranes surrounding heart cells. A prolonged QT interval indicates an abnormality in electrical activity that leads to irregularities in heart muscle contraction. One of these irregularities is a specific pattern of very rapid contractions (tachycardia) of the lower chambers of the heart called torsade de pointes, a type of ventricular tachycardia. The rapid contractions, which are not effective in pumping blood to the body, result in a decreased flow of oxygen-rich blood to the brain. This can result in a sudden loss of consciousness (syncope) and death. Causes and symptoms Both inherited and acquired forms of LQTS have been identified. Most acquired forms are thought to be due to certain drugs including adrenaline (epinephrine), several antihistamines and antibiotics, specific heart medications, diuretics, and others. It has been proposed, but not yet documented, that individuals who experience LQTS after using one of these medications, may actually have a genetic defect that increases their tendency to cardiac arrhythmias. Severe weight loss such as is associated with anorexia nervosa can also disrupt ion balances in the heart and result in prolongation of the QT interval. Three inherited forms of LQTS have been described to date. Jervell and Lange-Neilsen syndrome, named for the physicians who described the condition in 1957, is associated with congenital deafness and is inherited as an autosomal recessive trait. Romano-Ward syndrome, the most common inherited form of LQTS, was first described in the 1960's. It is inherited in an autosomal dominant pattern and is not associated with other physical impairments such as deafness. In 1995, a third type of LQTS was reported in to occur in association with bilateral syndactyly. Little is known about the inheritance of this form, except that reported cases have been sporadic with no associated family history of LQTS. As of early 2001, six different genes have been associated with the inherited forms of LQTS, and mutations in at least four of these genes had been reported in a number of affected individuals and families. The genes involved in LQTS play important roles in the formation of ion channels in the cell membrane, and, thus, mutations in these genes disrupt normal cardiac rhythms. LQTS usually presents with symptoms that constitute a life-threatening emergency. Sudden loss of consciousness or cardiac arrest can be brought on by emotional or physical stress in young, otherwise healthy individuals, both female and male. Fright, anger, surprise, sudden awakening as a result of loud sounds (alarm clock, telephone), as well as physical activities, especially swimming, have all been reported to precipitate an episode of cardiac arrhythmia in susceptible individuals. Sudden death often occurs. Although the information is preliminary, recent research has also suggested that a small number of SIDS (sudden infant death syndrome) cases may be due to mutations in one or more of the genes associated with LQTS. Diagnosis Problems exist in diagnosing LQTS. Although the method of diagnosis is the electrocardiogram, most young, healthy people do not routinely undergo this test, and, thus, their first, and possibly fatal, episode of LQTS comes without warning. In some cases, a non-fatal episode is mistakenly treated as a seizure, and, therefore, a follow-up assessment does not include an electrocardiogram. In addition, some cases of LQTS cannot be diagnosed by a routine electrocardiogram. That is, the QT interval is not found to be prolonged in routine testing. If LQTS is suspected either because of a previous episode of syncope or because of a family member with LQTS, an exercise electrocardiogram should be performed. In all instances where an individual is diagnosed with LQTS, family members should be thoroughly evaluated, and a detailed family history should be taken noting any individuals with episodes of sudden loss of consciousness and any cases of unexplained sudden death. Because many of the genes involved in LQTS have been identified, genetic testing can offer a more reliable means of diagnosis of other family members at risk. The first step in determining if this type of testing is appropriate in any particular situation is to consult a genetic counselor or medical geneticist. Treatment A conventional treatment is the oral administration of beta-blockers, medications that decrease the input from the sympathetic nervous system to the heart. Although beta-blockers do not correct the abnormalities in the ion channels of the heart cells, they do appear to decrease the occurrence of cardiac arrhythmias. However, these medications are not helpful in all cases, and are actually contraindicated in some individuals. Potassium supplementation is also being explored as a treatment in certain cases. As the genetics of LQTS becomes better understood, it should be possible to tailor treatments that will be effective for each of the various gene mutations. Alternative treatment In some patients, severing of the sympathetic nerve to the heart has decreased the occurrence of arrhythmias. Pacemakers and defibrillators appear to hold promise as new forms of treatment. As devices of this type are developed that are smaller in size, they may come into more widespread use, either alone or in conjunction with specific medications. Prognosis LQTS is a life-long condition. Individuals who are not diagnosed and treated are at an increased risk of syncope and sudden death. Adequate treatment can decrease this risk. There is no cure. Individuals with one of the inherited forms of LQTS are at risk of passing the mutation and the disease to their offspring. Prevention The risk of cardiac arrhythmias due to acquired forms of LQTS can be decreased by avoiding the medications and situations that trigger episodes. At present there is no genetic therapy to correct the gene mutations present in the inherited forms of LQTS, but individuals who are known to have an inherited form may also be able to lessen the risk of a life-threatening episode by avoiding such environmental triggers and by taking the appropriate medications. Key Terms Anorexia nervosa A loss of appetite for food not explainable by local disease. It is thought to have a psychological basis. Autosomal dominant A pattern of inheritance in which only one of the two copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. A person with an autosomal dominant disorder has a 50% chance of passing it to each of their offspring. Autosomal recessive A pattern of inheritance in which both copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. When both parents have one abnormal copy of the same gene, they have a 25% chance with each pregnancy that their offspring will have the disorder. Diuretic An agent that increases the production of urine. Electrocardiogram A record of the electrical activity of the heart showing certain waves called P, Q, R, S, and T waves. The Q, R, S, T waves are associated with contraction of the ventricles, the lower two chambers of the heart. Sympathetic nervous system A division of the autonomic nervous sytem, the portion of the nervous system that controls involuntary bodily functions such as heart rate. Syndactyly A fusion of two or more toes or fingers.
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
Definition Prolonged QT syndrome, also known as long QT syndrome (LQTS), refers to a group of disorders that increase the risk for sudden death due to an abnormal heartbeat. Description Abnormal heartbeats (cardiac arrhythmias) are a primary cause of sudden death, especially in the young population. In the United States, an estimated 1 in 300,000 individuals per year die suddenly due to irregular heart rhythms. One of the better understood causes of these arrhythmias is LQTS. The QT of LQTS refers to an interval between two points (Q and T) on the common electrocardiogram (ECG, EKG) used to record the electrical activity of the heart. This electrical activity, in turn, is the result of small molecules (ions such as sodium and potassium) passing in and out of channels in the membranes surrounding heart cells. A prolonged QT interval indicates an abnormality in electrical activity that leads to irregularities in heart muscle contraction. One of these irregularities is a specific pattern of very rapid contractions (tachycardia) of the lower chambers of the heart called torsade de pointes, a type of ventricular tachycardia. The rapid contractions, which are not effective in pumping blood to the body, result in a decreased flow of oxygen-rich blood to the brain. This can result in a sudden loss of consciousness (syncope) and death. Causes and symptoms Both inherited and acquired forms of LQTS have been identified. Most acquired forms are thought to be due to certain drugs including adrenaline (epinephrine), several antihistamines and antibiotics, specific heart medications, diuretics, and others. It has been proposed, but not yet documented, that individuals who experience LQTS after using one of these medications, may actually have a genetic defect that increases their tendency to cardiac arrhythmias. Severe weight loss such as is associated with anorexia nervosa can also disrupt ion balances in the heart and result in prolongation of the QT interval. Three inherited forms of LQTS have been described to date. Jervell and Lange-Neilsen syndrome, named for the physicians who described the condition in 1957, is associated with congenital deafness and is inherited as an autosomal recessive trait. Romano-Ward syndrome, the most common inherited form of LQTS, was first described in the 1960's. It is inherited in an autosomal dominant pattern and is not associated with other physical impairments such as deafness. In 1995, a third type of LQTS was reported in to occur in association with bilateral syndactyly. Little is known about the inheritance of this form, except that reported cases have been sporadic with no associated family history of LQTS. As of early 2001, six different genes have been associated with the inherited forms of LQTS, and mutations in at least four of these genes had been reported in a number of affected individuals and families. The genes involved in LQTS play important roles in the formation of ion channels in the cell membrane, and, thus, mutations in these genes disrupt normal cardiac rhythms. LQTS usually presents with symptoms that constitute a life-threatening emergency. Sudden loss of consciousness or cardiac arrest can be brought on by emotional or physical stress in young, otherwise healthy individuals, both female and male. Fright, anger, surprise, sudden awakening as a result of loud sounds (alarm clock, telephone), as well as physical activities, especially swimming, have all been reported to precipitate an episode of cardiac arrhythmia in susceptible individuals. Sudden death often occurs. Although the information is preliminary, recent research has also suggested that a small number of SIDS (sudden infant death syndrome) cases may be due to mutations in one or more of the genes associated with LQTS. Diagnosis Problems exist in diagnosing LQTS. Although the method of diagnosis is the electrocardiogram, most young, healthy people do not routinely undergo this test, and, thus, their first, and possibly fatal, episode of LQTS comes without warning. In some cases, a non-fatal episode is mistakenly treated as a seizure, and, therefore, a follow-up assessment does not include an electrocardiogram. In addition, some cases of LQTS cannot be diagnosed by a routine electrocardiogram. That is, the QT interval is not found to be prolonged in routine testing. If LQTS is suspected either because of a previous episode of syncope or because of a family member with LQTS, an exercise electrocardiogram should be performed. In all instances where an individual is diagnosed with LQTS, family members should be thoroughly evaluated, and a detailed family history should be taken noting any individuals with episodes of sudden loss of consciousness and any cases of unexplained sudden death. Because many of the genes involved in LQTS have been identified, genetic testing can offer a more reliable means of diagnosis of other family members at risk. The first step in determining if this type of testing is appropriate in any particular situation is to consult a genetic counselor or medical geneticist. Treatment A conventional treatment is the oral administration of beta-blockers, medications that decrease the input from the sympathetic nervous system to the heart. Although beta-blockers do not correct the abnormalities in the ion channels of the heart cells, they do appear to decrease the occurrence of cardiac arrhythmias. However, these medications are not helpful in all cases, and are actually contraindicated in some individuals. Potassium supplementation is also being explored as a treatment in certain cases. As the genetics of LQTS becomes better understood, it should be possible to tailor treatments that will be effective for each of the various gene mutations. Alternative treatment In some patients, severing of the sympathetic nerve to the heart has decreased the occurrence of arrhythmias. Pacemakers and defibrillators appear to hold promise as new forms of treatment. As devices of this type are developed that are smaller in size, they may come into more widespread use, either alone or in conjunction with specific medications. Prognosis LQTS is a life-long condition. Individuals who are not diagnosed and treated are at an increased risk of syncope and sudden death. Adequate treatment can decrease this risk. There is no cure. Individuals with one of the inherited forms of LQTS are at risk of passing the mutation and the disease to their offspring. Prevention The risk of cardiac arrhythmias due to acquired forms of LQTS can be decreased by avoiding the medications and situations that trigger episodes. At present there is no genetic therapy to correct the gene mutations present in the inherited forms of LQTS, but individuals who are known to have an inherited form may also be able to lessen the risk of a life-threatening episode by avoiding such environmental triggers and by taking the appropriate medications. Key Terms Anorexia nervosa A loss of appetite for food not explainable by local disease. It is thought to have a psychological basis. Autosomal dominant A pattern of inheritance in which only one of the two copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. A person with an autosomal dominant disorder has a 50% chance of passing it to each of their offspring. Autosomal recessive A pattern of inheritance in which both copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. When both parents have one abnormal copy of the same gene, they have a 25% chance with each pregnancy that their offspring will have the disorder. Diuretic An agent that increases the production of urine. Electrocardiogram A record of the electrical activity of the heart showing certain waves called P, Q, R, S, and T waves. The Q, R, S, T waves are associated with contraction of the ventricles, the lower two chambers of the heart. Sympathetic nervous system A division of the autonomic nervous sytem, the portion of the nervous system that controls involuntary bodily functions such as heart rate. Syndactyly A fusion of two or more toes or fingers.
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
The saddest part of prolonged QT sydrome is failure of doctors to recognize the full impact of prolonged QT syndrome. Unied States Army Woman Basketball Coach, a 6' 4" tall white woman went all the way to the NCAA basketball tounament and only to be found "sudden death" days after the loss of US Army to Tenneeseee. As a loyal fan of University of Tennesee, I am very addened by the sudden death and passing of a great woman basketball coach. We must be vigiliant to recognize Marfan's Syndrome among young adult and prolonged QT sudrome among athletics !
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
LQTS
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
EKG Attached Files: ekg_measurements_large.gif (12 KB, 21 downloads)
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babli
| Forum Guru Topics: 40 Posts: 424
Very good Dr AAAAA. Long QT syndrome (LQTS): The ECG demonstrates prolongation of the QT segment as demonstrated by a QT interval of 0.6 seconds (QTc = 0.61 s). This patient’s presentation of syncope with a similar history in an immediate family member is suggestive of congenital LQTS. The diagnosis of LQTS has been increasingly recognized as a cause of unexplained dizziness, syncope, and sudden cardiac death in otherwise healthy young individuals. The possibility of this diagnosis should be considered in any patient with a history similar to this patient’s. Congenital LQTS is now considered to be an inheritable abnormality in cardiac sodium and potassium channels. This “channelopathy” predisposes patients to episodes of torsades de pointes, especially when they are exposed to increased catecholamine levels (adrenergic dependent or tachycardia dependent). A related important point to assess in patients with a familial history of unexplained syncope or sudden death is an associated history of hearing loss. Some forms of LQTS (eg, Jervell and Lange-Nielsen syndrome) are accompanied by congenital neuronal deafness. Other forms (eg, Romano-Ward syndrome) do not have an associated hearing loss. The danger of a prolonged QT segment is the potential for degeneration to a specific type of polymorphic ventricular tachycardia known as torsade de points, translated as twisting of the points. Torsade de points is characterized by a ventricular rate greater than 200 bpm in which the QRS structure has an undulating axis that shifts polarity about the baseline. This rhythm can spontaneously convert to a sinus rhythm or degenerate into ventricular fibrillation. The rhythm itself or a brief degeneration into ventricular fibrillation can account for a clinical presentation of syncope in patients with LQTS. In addition to the congenital forms, acquired forms of LQTS are not uncommonly encountered in the ED. Acquired QT prolongation is usually precipitated by a slow heart rate and therefore called pause dependent in contrast to adrenergic dependent. Acquired forms are often the result of drug therapy with a variety of antiarrhythmic medications (primarily those of class IA, class 1C, and class III [though these are not always associated with QT prolongation]), phenothiazines (eg, haloperidol), cyclic depressants, antihistamines, and some antimicrobials. Resultant torsade de pointes is usually observed within 1-2 weeks of the start of the QT-altering medication. However, delayed presentations can also occur if other medications that affect the QT interval are added to the patient’s regimen. Other causes of pause-dependent prolongation of the QT interval are electrolyte disturbances (hypokalemia, hypomagnesemia, and, in rare cases, hypocalcemia), myocardial ischemia, hypothyroidism, use of drugs (eg, cocaine, amphetamines), and cerebrovascular accidents (intraparenchymal or subarachnoid hemorrhage). Treatment of patients with LQTS can be divided into short- or long-term strategies. Short-term strategies include immediate management of unstable rhythms (torsade de points) regardless of the specific etiology of the QT prolongation. In acquired LQTS, withdrawal of the offending agent and/or electrolyte repletion is often all that is necessary to prevent recurrences in most patients. The exception is in patients with sick sinus syndrome or atrioventricular blocks in whom a pause or bradycardia precipitates torsades. These patients require permanent pacemakers. In contrast, all patients with congenital LQTS require long-term treatment. The cornerstone of therapy is life-long adrenergic blockade with beta-blockers. Additional therapies include left thoracic sympathectomy, permanent implantation of pacemakers or cardiac defibrillators, and other treatments specific to channelopathy. (For further discussion of treatment options, please see any of the references cited below.) This patient was admitted to a cardiac telemetry unit after a discussion with the on-call cardiologist for further evaluation and management. She had a suspected congenital adrenergic-dependent form of LQTS, and beta-blocker therapy was initiated. Other members of her family were encouraged to seek consultation for LQTS. As a final teaching point for this case, a QT interval greater than 0.44 seconds is generally considered to be prolonged, but established formulas provide validated values. The QT interval is affected by the heart rate, and a corrected value referred to as the QTc is calculated with the following formula: QTc = QT/√RR interval. In this case with an RR interval of 0.96 seconds, the QTc is equal to 0.61 seconds. The QTc value must then be compared to the maximal QT interval allowed for the heart rate and gender of the patient. Reference values for the maximal allowed QT interval can be found by using established tables, but in this case, for a heart rate of 65 bpm in a woman, the maximal normal QT interval is 0.42 seconds. Because the QTc is greater than the maximal allowed QT interval, the interval is prolonged.
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guayoman
| Forum Elite  Topics: 44 Posts: 273
I liked your final explanation of QTc. In my years in the hospital environment, nobody expained it that well.
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d_raza1
| Forum Newbie Topics: 36 Posts: 106
Why pregnancy test was advised? I think pregnancy should be little advanced to cause syncope, 2ndly if we can rule out pregnancy by history (for example at the day of presentation it was 5th day of her cycle), do we still need to do the test. Is this test a routine for any female patient of reproductive age presenting with any complaint?
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
You believe in patient's history especially it is her 5th day of the cycle. There are academic and clinical medicine and clinical medicine tells you to do a pregnancy test because a 16 year old telling you she is on her 5th day of the cycle. Dr. d_razal, Do you believe in her???? LOL !!
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AAAAA
| Forum Fanatic Topics: 159 Posts: 2013
This is very basic medicine. All female patients who come in c/o of syncope should have a pregnancy test to rule out IUD or ectopic. It is part of mediicine we have to accept.
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