Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018799 (heart disease)
 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Brugada syndrome (BRS) is a hereditary cardiac condition (characteristically with a gene mutation affecting sodium channel function) identified by an elevated terminal portion of the QRS complex (prominent J wave) followed by a descending ST-segment elevation ending in a negative T wave in the right precordial leads, and malignant tachyarrhythmias in patients without demonstrable structural heart disease. We report a patient with a previous history of epilepsy treated with psychotropic drugs (with a sodium channel blocking effect) and chronic renal failure on haemodialysis who developed hyperkalaemia (6.6 mmol/l) and ECG findings resembling BRS. This condition was manifested by the prominent J wave, the coved-type ST-segment elevation and the negative T wave in the right precordial leads. These ECG changes disappeared after haemodialysis when the potassium became normal. Subsequently, a flecainide test did not reproduce ST-segment elevation. We conclude that hyperkalaemia associated with cardiac membrane active drugs may cause ECG changes mimicking the Brugada syndrome.
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PMID:Transient Brugada-type electrocardiographic abnormalities in renal failure reversed by dialysis. 1241 61

The flecainide test is widely used in Brugada syndrome. However, its reproducibility and safety remain ill-defined. This study included 22 patients (18 men, mean age 34 years). Mutations in the SCN5A gene were found in eight patients. Two patients had aborted sudden cardiac death, 8 had syncope/presyncope, and 12 were asymptomatic. The ECG was diagnostic in 19 patients and suggestive in 3. At baseline, 21 of 22 patients underwent a flecainide test (2 mg/kg IV bolus over 10 minutes). In 21 of 21 patients the test was diagnostic or amplified the typical ECG pattern. At the end of drug infusion, sustained VT lasting 7-10 minutes developed in two patients. A second flecainide test was performed within 2 months in 20 patients. The test was not repeated in the two patients with prior development of VT. The flecainide test was diagnostic in 20 of 20 patients. Sustained VT occurred in one patient and recurrent VF in another. The reproducibility of the flecainide test was 100%. In 4 (18%) of 22 patients major VAs were documented after the end of flecainide infusion. VA occurred in 3 (43%) of 7 patients with, versus 1 (7%) 15 without SCN5A gene mutation (P < 0.05). No diagnostic ECG changes or arrhythmias developed in 25 control patients without structural heart disease who underwent the same study protocol. This study shows a high flecainide reproducibility, supporting its diagnostic value in Brugada syndrome. However, the occurrence of major VA, significantly higher in patients with documented SCN5A gene mutation, including in asymptomatic patients, mandates the performance under appropriate medical supervision. Whether a slower rate of drug infusion can lower the risk of VA induction, while maintaining the sensitivity of the test should be explored.
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PMID:Flecainide test in Brugada syndrome: a reproducible but risky tool. 1268 41

Febrile illness has been rarely reported to modulate ST segment elevation in right precordial leads on ECG or even precipitate ventricular fibrillation in patients with Brugada syndrome. We report the case of a patient whose Brugada ECG pattern was unmasked by hyperthermia secondary to acute cholangitis. Serial ECGs showed progressive attenuation of ST segment elevation as body temperature gradually returned to normal. Structural heart disease was ruled out. Intravenous flecainide injection reproduced a less remarkable ST segment elevation. Genetic screening demonstrated a single amino acid substitution (H681P) in the SCN5A gene, thus confirming the diagnosis of Brugada syndrome. In vitro expression of this newly characterized genetic defect revealed novel biophysical abnormalities consisting of a shift in both steady-state activation and inactivation, resulting in a 60% reduction of sodium window current. Thus, SCN5A-H681P mutation induces a significant loss of transmembrane current and is clinically associated with a pathologic phenotype that is elicited by hyperthermia. Overall the observed clinical features are in agreement with previous observations and strongly suggest that fever may be an environmental modifier among Brugada syndrome patients with a detrimental (and possibly arrhythmogenic) effect on cardiac repolarization.
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PMID:A newly characterized SCN5A mutation underlying Brugada syndrome unmasked by hyperthermia. 1467 48

A 42 year old male patient presented with atypical ECG pattern at rest and reported that his brother died suddenly of unknown reasons at the age of 40. A performed pharmacological testing with ajmalin discovered strong ST-segment elevations in lead V(1) and V(2) in combination with an incomplete right bundle branch block. As a result, the diagnosis Brugada syndrome was established. The Brugada syndrome is a primary cardiac conduction disturbance without structural heart disease and is associated with an increased risk of sudden cardiac death caused by life threatening ventricular tachyarrhythmia. It is an inherited disease displaying an autosomal dominant mode of transmission with an incomplete penetrance, especially prevalent in females. In some regions like the southeast of Asia and Japan it is endemic. The mutation is linked to the sodium channel gene SCN5A. The annual mortality rate is estimated 30 per 100.000 persons. Today, exact diagnostic criteria do not exist. The diagnosis is based on the typical ECG pattern, combined with clinical symptoms, and a family history of sudden cardiac death. The currently suggested therapy consists of the implantation of an internal defibrillator.
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PMID:[Atypical resting ecg pattern in a patient with a positive family history of sudden cardiac death]]. 1456 68

A 56-year-old man with Brugada syndrome presented with ventricular fibrillation induced by administration of pilsicainide. He had syncope at age 46 years, and his uncle suddenly died of unknown cause. He had taken pilsicainide (150 mg/day) for paroxysmal atrial fibrillation, and suffered from syncope due to ventricular fibrillation. Coved type ST elevation was observed in the V1 lead, and saddle back type ST elevation was observed in the V2 lead. The ST elevation gradually recovered after stopping pilsicainide therapy. No structural heart disease was found. After intravenous injection of pilsicainide, the ST segment elevated in the V1 and V2 leads. Ventricular fibrillation was induced by triple extrastimulation at the right ventricular apex. The diagnosis was Brugada syndrome, and a cardioverter-defibrillator was implanted. Brugada syndrome should be considered before administering pilsicainide.
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PMID:[Brugada syndrome associated with ventricular fibrillation induced by administration of pilsicainide: a case report]. 1465 12

Syncope is a frequent problem in childhood; generally, it is an isolated event and the common causes are benign. However, in some circumstances, syncope can herald a potentially lethal problem, especially when occurring during exercise. Routine evaluation includes history, physical examination and a 12-lead standard ECG should be performed in all cases. Worrying features which should be an indication for further investigation include syncope during exercise, collapse in a swimming pool, history of familial sudden death, and abnormalities on clinical exam or ECG. Structural cardiac abnormalities that may cause syncope and sudden death include aortic stenosis, hypertrophic cardiomyopathy and coronary malformations. All children with unrepaired or repaired congenital heart disease who experienced a syncope should be referred to a specialist. Primary arrhythmias that are easily diagnosed on ECG are the long QT syndrome, complete atrio-ventricular block and Wolff-Parkinson-White syndrome; ST elevation in V1-V3 may reveal a Brugada syndrome. Another arrhythmia which is known to be potentially fatal if undiagnosed is the catecholaminergic ventricular tachycardia; the baseline ECG is normal but the arrhythmia is easily reproduced during exercise testing. Finally, vasovagal syncope is the most likely cause of syncope in the young and it usually easily recognized.
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PMID:[Cardiac syncope in children]. 1476 42

In 1992, Brugada and Brugada described 8 patients with a history of aborted sudden death and a distinct ECG pattern of right bundle-branch block with ST segment elevation in leads V1-V3 and normal QT interval in the absence of any structural heart disease. It is called Brugada syndrome now and is believed to be responsible for 4-12% of all sudden deaths and around 20% of deaths in patients with structurally normal hearts. Although this syndrome is observed worldwide and the exact prevalence is unknown, it is more common in the Southeast Asian countries. Repeated syncope, ventricular fibrillation, and sudden cardiac death have been reported in patients with Brugada syndrome. The clinical presentation of Brugada syndrome is distinguished by a male predominance and the appearance of arrhythmic events at an average age of 40 years. The Brugada syndrome is inherited in an autosomal dominant manner with incomplete penetrance and an incidence ranging between 5 and 66 per 10,000. The surface ECG manifestations of the syndrome can transiently disappear, but can be unmasked by potent sodium channel blockers in some cases. Mutations of the cardiac sodium channel SCN5A have been detectable in <20% of patients with Brugada syndrome. Recent genetic studies have confirmed the genetic heterogeneity of the disorder. Antiarrhythmic drugs appear to be of little use in prolonging survival and in preventing recurrences of ventricular arrhythmias. To date, implantable cardioverter defibrillator remains the best therapy to prevent sudden death in these patients.
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PMID:Brugada syndrome--an under-recognized electrical disease in patients with sudden cardiac death. 1496 59

Sudden unexpected cardiac death generally occurs in persons with known or previously unrecognized heart disease. However, it has become evident that it occurs often enough in patients without any identifiable structural abnormality to warrant the cardiologist's attention. Mostly, it concerns young, active, and otherwise healthy individuals. This paper focuses on various categories of patients with life-threatening events considered to have occurred on a solely "electrical" basis. Currently, several entities are recognized with distinct electrophysiological abnormalities, including Wolff-Parkinson-White syndrome, long QT syndrome, the Brugada syndrome, short-coupled torsade de pointes, and catecholamine-induced polymorphic ventricular tachyarrhythmia. The remaining patients without such distinct abnormalities are categorized as having idiopathic ventricular fibrillation. Although mechanical cardiac function may seem normal, such patients might have certain discrete anatomic abnormalities, unidentifiable with current investigational tools. Possibly in the future, with development of newer and more sophisticated tools (magnetic resonance imaging, positron emission tomography, genetic testing), some or all cases of idiopathic ventricular fibrillation must be redefined as having specific genetic and/or anatomic bases. All patients successfully resuscitated from cardiac arrest due to ventricular tachyarrhythmia without clear precipitating factors (acute myocardial infarction, severe electrolyte or metabolic disturbances) are at high risk of recurrences. Long-term prophylactic therapy is indicated. Contrasting with older belief, survivors of idiopathic ventricular fibrillation are now also considered high-risk patients. The implantable cardioverter-defibrillator appears to be the safest and most effective therapy.
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PMID:Sudden death in patients without structural heart disease. 1506 19

The clinical approach to the patient with nonsustained ventricular tachycardia (NSVT) should always be considered within the particular clinical context in which the arrhythmia occurs. In the documented absence of heart disease, spontaneous NSVT does not carry any adverse prognostic significance. Exercise-induced NSVT may predict increased cardiac mortality. In ischaemic patients with a left ventricular ejection fraction (LVEF) < 40%, NSVT has an adverse prognostic significance and electrophysiologic testing is indicated with a view to ICD implantation. In patients with LVEF > 40% the independent prognostic significance of NSVT is unknown. The prognostic value of NSVT in patients with dilated cardiomyopathy is not known. NSVT in young patients with hypertrophic obstructive cardiomyopathy carries an adverse prognostic significance. The prognostic value of NSVT in conditions such as the long-QT syndromes, primary ventricular fibrillation, and Brugada syndrome, as well as in patients with hypertension and valvular disease, has not been established.
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PMID:Nonsustained ventricular tachycardia: where do we stand? 1523 66

Syncope, defined as a transient loss of consciousness and postural tone with spontaneous recovery and no neurologic sequelae, is among one of the most common causes of consultation with a physician. The diagnostic workup is complex but can be simplified if focused on the underlying condition. Prognosis is highly dependent on the presence or absence of structural heart disease, primarily the presence of cardiomyopathy regardless of etiology, particularly if the left ventricular (LV) function is less than 35%. The diagnostic approach to the patient with recurrent syncope and no structural heart disease is targeted to rule out neurally mediated causes. This approach usually includes a tilt table test (ie, head-up tilt), carotid sinus massage in patients older than 55 years, and an adenosine challenge test in patients who remain with unexplained syncope. Unexplained syncope in patients with reduced LV function (< 35%) may be potentially life-threatening. Infrequent causes of syncope should be sought in younger patients with a family history of sudden cardiac death. Channelopathies such as the long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia are among this variety. Therapy should address the potential mechanism of syncope. In neurally mediated causes, restoration of orthostatic tolerance, primarily by increasing volume during orthostatic stress, is recommended. Physiologic countermaneuvers and increase in salt and water intake are usually the initial therapy. With syncope in patients with an LV dysfunction (< 35%), an ICD is frequently recommended after ruling out common causes of syncope. Syncope in the elderly is usually multifactorial and therapy should include reassessment of multiple medications, which can promote neurally mediated syncope as well as searching for bradycardic causes. Empiric pacing may be used in this complex group of patients.
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PMID:Current Management of Syncope: Treatment Alternatives. 1532 13


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