Current Concepts in Long QT Syndrome

Li, H.; Fuentes-Garcia, J.; Towbin, Jeffrey A.

doi:10.1007/s002460010132

Cited by 30 publications

(21 citation statements)

References 67 publications

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“…The HERG channels specify one component of the delayed rectifier that contributes to the repolarization phase of cardiac action potential. One form of inherited long QT syndrome, LQT2, results from genetic defects in herg1 gene and predisposes affected individuals to potentially lethal arrhythmias (8,9). However most often the same sickness is derived from the nonspecific blockade of cardiac HERG current by various commonly used medications, such as class III antiarrhythmics, antihistaminics, or antipsychotics (10).…”

mentioning

confidence: 99%

New Binding Site on Common Molecular Scaffold Provides HERG Channel Specificity of Scorpion Toxin BeKm-1

Korolkova

Bocharov

Angelo

et al. 2002

Journal of Biological Chemistry

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The scorpion toxin BeKm-1 is unique among a variety of known short scorpion toxins affecting potassium channels in its selective action on ether-a-go-go-related gene (ERG)-type channels. BeKm-1 shares the common molecular scaffold with other short scorpion toxins. The toxin spatial structure resolved by NMR consists of a short ␣-helix and a triple-stranded antiparallel ␤-sheet. By toxin mutagenesis study we identified the residues that are important for the binding of BeKm-1 to the human ERG K ؉ (HERG) channel. The most critical residues (Tyr-11, Lys-18, Arg-20, Lys-23) are located in the ␣-helix and following loop whereas the "traditional" functional site of other short scorpion toxins is formed by residues from the ␤-sheet. Thus the unique location of the binding site of BeKm-1 provides its specificity toward the HERG channel.

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mentioning

confidence: 99%

New Binding Site on Common Molecular Scaffold Provides HERG Channel Specificity of Scorpion Toxin BeKm-1

Korolkova

Bocharov

Angelo

et al. 2002

Journal of Biological Chemistry

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“…The most common arrhythmia is associated with long QT syndrome (LQTS), characterized by a prolonged QT interval on ECG precipitating torsade de pointes and cardiac arrest. Inherited forms of LQTS are ion channelopathies resulting in prolonged cardiac repolarization (6). In congenital LQTS, syncope or sudden death may be triggered by exertion, swimming, sleep deprivation, loud noises or strong emotions -the trigger varies with the genotype (7).…”

Section: Discussionmentioning

confidence: 99%

When are episodes of loss of consciousness life-threatening?

Brna

Camfield

et al. 2006

Paediatrics &Amp; Child Health

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Episodic loss of consciousness is common in the paediatric population. While the majority of cases are due to benign conditions, lifethreatening causes must be promptly identified. The present paper presents a case of recurrent loss of consciousness associated with convulsive activity and subsequent cardiac arrest due to a rare inherited ion channel disease known as Brugada syndrome. The case highlights the challenges of distinguishing epilepsy from convulsive syncope and the potentially disastrous consequences of an undiagnosed cardiac etiology. The most important paediatric causes of paroxysmal loss of consciousness and their salient features are reviewed. Clinical features suggesting a cardiac cause are emphasized because early recognition of these cases is critical. T here are many causes of brief episodes of loss of consciousness (LOC), but most are benign. Identifying the few patients with an ominous cause is challenging. Syncope is often misdiagnosed as epilepsy, leading to unnecessary and ineffective treatment -an unsatisfactory, but not dangerous, error. More concerning is misdiagnosis of a cardiac cause of LOC, which may be fatal with the next attack. We present a case of paroxysmal LOC that illustrates the clinical features that should alert the clinician to potentially life-threatening cardiac conditions. CASE PRESENTATIONA 15-year-old boy experienced a sudden LOC while standing. Without warning, he fell down, and was unconscious with tonic limb extension for 5 min. He was described as pale, but he recovered quickly without residual drowsiness. Head computed tomography was normal.One week later, during sleep, he had tonic limb extension, LOC and gasping respirations. Epilepsy was diagnosed and carbamazepine started. Frequent events continued and he was admitted to hospital. On day 2, sudden LOC occurred with tonic stiffening and eye deviation, quickly followed by cardiac arrest. He was successfully resuscitated with multiple defibrillations, and an amiodarone load was given for atrial fibrillation. He was then transported to a tertiary care children's hospital.His initial electrocardiogram (ECG) showed a prolonged QT interval (QTc=0.49), which was believed to be secondary to amiodarone; two follow-up ECGs were normal. An echocardiogram, interictal electroencephalogram (EEG) and brain magnetic resonance imaging scan were normal.Previous normal cognitive and physical development was documented. The patient had no history of shortness of breath, chest pain, palpitations or syncope. There was no family history of epilepsy, syncope, arrhythmia or sudden death. On examination, he was alert and oriented to person but initially disoriented to time and place. By day 3, he had recovered completely with normal cardiac and neurological examinations.An ECG from the day of his initial event was reviewed and showed ST segment elevation of V1 to V3 and right bundle branch block (RBBB) -a pattern consistent with Brugada syndrome. Holter monitoring showed incomplete RBBB, nondiagnostic T-wave changes and frequent prem...

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“…Potassium deficiency secondary to loss of intestinal secretions, to eating disorders or to use of diuretics prolongs the QT interval on standard electrocardiogram and predisposes to cardiac arrhythmias culminating in syncope or sudden death [3, 4]. Hypokalemia is sometimes severe in patients with primary renal hypokalemic alkalosis.…”

Section: Introductionmentioning

confidence: 99%

Electrocardiographic QT Prolongation and Sudden Death in Renal Hypokalemic Alkalosis

Calderari

Vigier

Bettinelli

et al. 2002

Nephron

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A 3-year-old boy was found to have a mixed tubulopathy with hypokalemia (1.9 mmol/l), alkalosis (blood pH 7.51, plasma carbon dioxide pressure 46 mm Hg, plasma bicarbonate 35.7 mmol/l) and hypophosphatemia (1.21 mmol/l). An electrocardiogram disclosed a prolonged heart rate corrected QT interval of 490 ms. The boy was put on potassium chloride, phosphate and nonsteroidal anti-inflammatory agents. With this treatment plasma phosphate normalized and plasma potassium increased up to 3.0–3.3 mmol/l. Three years later the child, who did not have history of gastroesophageal reflux or epileptic convulsions, suddenly died during sleep. The cause of death could not be determined through gross examination of the body. The history of hypokalemia, the QT-prolongation, the sudden death and the failure to assess the cause of death through gross examination of the body suggest that death was caused by an arrhythmia secondary to hypokalemia.

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Current Concepts in Long QT Syndrome

Cited by 30 publications

References 67 publications

New Binding Site on Common Molecular Scaffold Provides HERG Channel Specificity of Scorpion Toxin BeKm-1

New Binding Site on Common Molecular Scaffold Provides HERG Channel Specificity of Scorpion Toxin BeKm-1

When are episodes of loss of consciousness life-threatening?

Electrocardiographic QT Prolongation and Sudden Death in Renal Hypokalemic Alkalosis

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