Congenital short QT syndrome. A review.

Sudden cardiac death in individuals with structurally normal hearts accounts for approximately 20% of sudden cardiac death cases. Patients in this subgroup suffer from what has been named "electrical diseases" which are gradually coming into focus as inherited ion channelopathies, diseases of anchoring proteins or of intracellular calcium regulating proteins. From 1993, the Short QT Syndrome (SQTS) came to our attention, as a new inherited "electrical disease" associated with increased risk of sudden cardiac death and atrial fibrillation. Mutations of Ikr, Iks, Ikl channels cause dysfunctional Iks, Ikr, Ikl channels with an increase in the net outward K current leading to shortening of repolarization. This in turn leads to a shorter QT interval on the ECG and shorter atrial and ventricular refractory periods with increased susceptibility to VF and AF. There seems to be an autosomal dominant mode of inheritance. The clinical profile of SQTS consists of: family history of sudden cardiac death, personal history of palpitations, syncope, dizziness, resuscitated SCD, history of AF and documented VF. It is important to emphasize that SQTS is symptomatic from early age (new-born) to old age. Therefore, it is possible that SQTS accounts for some of the sudden infant death syndrome cases and for some cases of AF, especially lone AF. The only efficient treatment for ventricular arrhythmias is ICD, associated with drugs (Quinidine or Propaphenone) for AF prophylaxis and for reducing the number of ventricular arrhythmic events (and ICD discharges).

The tachyarrhythmic cardiomyopathy--a rare entity in childhood.

UNLABELLED: Persistent disturbances of rhythm with high heart rate may lead to reversible depression of left ventricular function and biventricular failure. This phenomenon may appear also in children with incessant supraventricular tachycardia. Because in most cases these patients are long time asymptomatic the diagnosis of these arrhythmias is very difficult and frequently is belated. In case of correct treatment of the arrhythmia, the cardiac function improves rapidly. OBJECTIVE: To present a number of cases of incessant supraventricular tachycardia in children, which has led to tachyarrhythmic cardiomyopathy and heart failure. MATERIAL AND METHOD: A number of six patients (pts.), aged between 3 years 10 m - 16 y, hospitalized between January 1st, 2001 - January 1st , 2004 were taken in study. All patients had long crisis of supraventricular tachycardia with incessant character. A clinical exam, an ECG, a chest X-ray film and an echocardiography were made to all patients. An electrophysiologic study was made in two cases. The emergency therapy was the drug therapy. RESULTS: At the moment of hospitalization all patients had a depression of the contractile function of the myocardium. After the control of the arrhythmia the ejection fraction recovered in a period between 3 months and one year. CONCLUSION: The disturbances of rhythm may induce a depression of the contractile function of the myocardium, which is reversible in many cases. The correct antiarrhythmic treatment led to the improvement of the heart failure in this case.