Tachyarrhythmic syncopes in children with structurally normal hearts with and without QT-prolongation in the electrocardiogram

Abstract

Forty children with presumed ventricular tachyarrhythmic syncopes in the absence of structural heart disease were studied. Twenty-nine patients, one of whom was deaf, had a prolonged QT-interval in the resting electrocardiogram (Group 1); eleven patients had a normal QT-interval (Group 2). The median QTc-interval vas 0.51 s in Group 1 and 0.40 s in Group 2. Familial occurrence suggesting autosomal dominant inheritance was found in 21 of 28 normally hearing patients in Group 1 and in 2 of 11 patients in Group 2. Syncopes were definitely stress-induced in 22 patients in Group 1 and in all 11 patients in Group 2. Of 23 patients in Group 1 in whom an electrocardiogram was obtained during physical exercise, only one showed severe ventricular dysrhythmia. In contrast, all eleven patients in Group 2 developed severe ventricular dysrhythmia with exercise. Treatment with beta-blocking medication prevented further syncopes in 15 of 19 patients with several previous attacks in Group 1 and in 3 of 5 patients of Group 2. Four of the 29 patients in Group 1 died suddenly and one more remained apallic after an attack. Of the 11 patients in Group 2, four died suddenly and one retains severe cerebral damage after resuscitation from ventricular fibrillation. We conclude that, besides the group of patients with the long QT-syndrome, there may be a distinct group of patients with a consistently normal QT-interval and severe ventricular dysrhythmia with exercise. Patients of both groups are threatened by sudden death and are improved by treatment with beta-blocking medication.

Catecholaminergic polymorphic ventricular tachycardia: electrocardiographic characteristics and optimal therapeutic strategies to prevent sudden death

“…16 Polymorphic or bidirectional ventricular tachycardia may develop in association with a prolonged QT interval. [17][18][19] When provoked by exercise, it is unclear whether the resulting polymorphic ventricular tachycardia is the same clinical entity and has the same mechanism with a long QT interval as without.…”

Ventricular tachycardia and exercise related syncope in children with structurally normal hearts: emphasis on repolarisation abnormality.

“…,B Blockers are effective in this type of ventricular tachycardia. [5][6][7] Ventricular tachycardia typical of the long QT syndrome is torsades de pointes. It is important to identify the cause because of the association with sudden death in this syndrome.…”

Syncope in Childhood: A Case Control Clinical Study of the Familial Tendency to Faint

“…Autosomal dominant familial cardiac causes of "syncope" are well described. 6 We attempted to exclude such rare disorders as prolonged QT interval by excluding families with a history of sudden death and by insisting on a typical history of vasovagal or vasodepressor syncope. No detailed cardiac rhythm studies were carried out.…”