Postexercise ventricular tachycardia in children

Abstract

Exercise-induced ventricular tachycardia (VT) in children has been reported in your journal [1] and in other publications [2,4,5] . We should like to describe two children in whom VT was depressed during effort, but became most pronounced during the recovery period .Case 1 . A 14-year-old boy complained of intermittent palpitations, especially after exertion . No signs of organic heart disease were detected . The resting electrocardiogram (ECG) showed sinus rhythm, with short runs (3-8 complexes) of VT after each 3rd-5th sinus beat . On repeated bicycle exercise testing, the ventricular arrhythmia gradually diminished and was abolished completely once the sinus rate exceeded 115 beats per minute (bpm) ; I min after stopping the exercise testing, runs of VT at a rate of 130-140 bpm and lasting for 1-2 min were recorded . They were accompanied by dizziness . A 24-h dynamic electrocardiographic tape recording showed similar results, namely, short runs of VT during rest or mild exercise, its abolition during effort, and runs of sustained VT on recovery . Amiodarone at a loading dose of 600 mg daily and a maintenance dose of 200 mg daily was fully effective in suppressing the arrhythmia .Case 2 . A 14-year-old girl complained of severe vertigo following effort . Physical and echocardiographic examinations of the heart disclosed no signs of organic heart disease . The resting ECG disclosed multiple ventricular premature complexes (VPCs) and infrequent runs of 3-4 successive VPCs (VT). The arrhythmia was completely abolished during exercise testing and on spontaneous effort . Runs of VT lasting 20-30 s at a rate of 108 bpm were recorded during the first 2-3 min of the recovery period . Amiodarone was given in the same schedule as in case I and was, likewise, fully effective in abolishing the arrhythmia .Overdrive suppression of ventricular arrhythmias is a well-recognized phenomenon . It was noted that an aggravation of the arrhythmia may be observed during the recovery period [6]. The two patients described here reported dizziness and even near syncope after effort. In both of them, overdrive suppression of VPCs and short runs of VT were recorded, but relatively long runs of VT developed in both of them 1-3 min after the abrupt cessation of effort . This phenomenon may be explained on the Pediatric Cardiology n Springer-Verlag New York Inc . 1986 basis of elevated levels of catecholamines acting on the now "unprotected" myocardium .Amiodarone was effective in both cases . It was preferred to beta-blocking drugs for the following reasons: (a) Its very long-acting effect partially solves the problem of the poor compliance of children with relatively few symptoms . (b) Only a few side effects, all of them reversible, were reported in a large series of children treated with the drug [3] .However, the relatively short experience with amiodarone and reports on possible serious and irreversible side effects (like pulmonary fibrosis) makes it mandatory to try to stop the drug as soon as possible or to substitute other effec...