Qtu‐abnormalities, Sinus Bradycardia and Adams‐stokes Attacks Due to Ventricular Tachyarrhythmia

Abstract

In 1957, Jervell & Lange-Nielsen (6) first described the syndrome consisting af congenital deaf-mutism, prolongation of the QT-interval in the electrocardiogram, and syncopal attacks. Later, it was found that QT-prolongation and tachyarrhythmic Adams-Stokes attacks may also occur in patients with normal hearing (12,13). This report concerns a young girl with tachyarrhythmic Adams-Stokes attacks, normal hearing, normal resting QTinterval, and a striking sinus bradycardia. CASE REPORTA 10-year-old girl was referred to the University Hospital because of a cardiac arrhythmia detected during introduction of anaesthesia for tonsillectomy. At the age of 1 1/2 years, an unusually slow pulse was first noted. Since the age of 3 years she had frequent attacks ranging in severity fiom brief dizziness, pallor and nausea to sudden episodes of unconsciousness. These attacks always occurred in connection with physical exercise or excitement. The child was believed to have epileptic seizures and was treated without success with various anticonvulsive medications, even though the electroencephalogram was normal.There is no history of deafness, syncopal episodes or sudden death in the family on either side. The patient's father has a sinus bradycardia of approximately 50 beats/min. He and his mother as well as the patient's two brothers show a slightly prolonged QT-interval (QTc 0.43-0.45 sec).The child's physical examination was unremarkable except for a slow heart rate of 50 beats/min. Elec-troencephalogram and routine laboratory studies were normal except for a microhaematuria, for which no cause could be found. On the chest roentgenogram, the heart was of normal size and configuration. The electrocardiogram at rest revealed sinus bradycardia of 48 beatslmin (Fig. 1). The PQ-interval was short (0.12 sec) but still within the normal range. The T-waves were rather flat but there were prominent U-waves as is often seen with bradycardia. The QTinterval was not prolonged (QT 0.45 sec, QTc 0.40 sec, QT ratio 1.00). During exercise on a bicycle ergometer with a load of 50 watts the regular sinus rate rose to 90 to 100 beats/min while the QTc increased up to 0.53 sec and the QT ratio up to 1.32. The U-waves remained prominent. At a heart rate of 90 to 100 beats/min, ventricular arrhythmia regularly developed, either as uni-or multifocal bigemini (Fig. 20) or as short runs of multifocal ventricular beats (Fig. 26) or, on one occasion, as multifocal ( Fig. 3a) and partly bidirectional (Fig. 36) ventricular tachycardia of approximately 200 beats/min. SPECIAL STUDIESRight heart catheterization revealed no evidence of organic heart disease. Electrical stimulation of the superior vena cava-right atrial junction resulted in an atrial rhythm with 1 : 1 conduction to the ventricles up to a frequency of 170 beats/min, when Wenckebach periods appeared. At no time were extra-systoles observed. Up to a frequency of 130 beats/ min the T-waves could be separated from the Pwaves; at this frequency QT was 0.32 sec, QTc 0.47 sec, and the QT ratio 1.18. ...

Evaluation of children with ventricular arrhythmias.

“…Wennevold et al (1965) emphasized its use as a diagnostic tool in children with syncope, and subsequent reports have confirmed its importance. Exercise testing is recommended for the detection of arrhythmias in patients with mitral leaflet prolapse syndrome (Gooch et al, 1972), sick sinus syndrome (Scott et al, 1976), and with QT abnormalities (Bernuth et al, 1973). In our experience the abnormal rhythms were detected more quickly and accurately by exercise testing than by Holter monitoring.…”

The Prolonged Q-T Syndrome. A Review with Anaesthetic Implications and a Report of Two Cases

“…It was first described by von Bernuth "t al. 10 who stated that although Q-T prolongation is considered an essential part of the syndrome it is of variable degree in different patients, and within the same patient at different times, and may be rather slight. The second case described in this paper typifies this form of the condition.…”