Bradycardia preceding apneic attacks in low-birthweight infants. The relationship and management

Selective denervation of the S-A node in the treatment of progressive central vagal bradycardia

The condition of central hypervagism and central vagal bradycardia, up to now, have been largely overlooked. Selective surgical vagal denervation of the SA node for progressive central and local episodic reflex arc bradycardia, via right thoracotomy, is a well-tolerated procedure even in the debilitated child. The bradycardia must, of course, be atropine-responsive. It appears to be a valuable alternative to pacemakers, especially because of the necessity of using the sequential type in this form of heart block. Our follow-ups are from 8 months to 13 years in seven children (five central and two peripheral). Up to now, in an admittedly small series, there has been only one recurrence of bradycardia. This was from crossover left vagal innervation of the SA node. The incidence of this is 10% to 15%. It responded to right cervical vagotomy, following a preliminary diagnostic novocain block. We hope that these findings may lead to more awareness and investigations of conditions due to autonomic dysfunction--both central and peripheral--which may help among other conditions in the elucidation and prevention of sudden infant death syndrome (SIDS) and other related problems, and that this surgical approach will be a definitive means for the control of refractory, persistent, or recurrent vagal bradycardia.

Incidence and significance of primary abnormalities of cardiac rhythm in infants at high risk for sudden infant death syndrome

The exact relationship between cardiac arrhythmias and sudden infant death syndrome (SIDS) is uncertain. Several reports have implicated both ventricular and supraventricular arrhythmias in isolated cases, but there have been no studies of the incidence or type of arrhythmias that occur in populations at risk for SIDS. Of 1699 infants at high risk for SIDS, 60 (4%) were found to have a primary cardiac arrhythmia (i.e., not associated with disordered respiration or apnea). The incidence of atrial and ventricular premature beats, supraventricular tachycardia, and Wolff-Parkinson-White syndrome was similar to the incidence found in normal infants. Primary bradycardia (defined as a heart rate less than 60 for greater than 10 s not associated with abnormal respiration) was the most common arrhythmia, occurring with a frequency and severity not seen in normal infants. Thirty-two infants experienced periodic bradycardia. In 19 of these latter infants, there were symptoms associated with these bradyarrhythmias that necessitated treatment. Heart rates as low as 20 beats/min were recorded. One infant presented with an episode of ventricular fibrillation and on further evaluation was noted to have recurrent bradyarrhythmias. In no infant was there abnormal prolongation of the QT interval. Primary bradyarrhythmias are seen at an increased incidence in infants at high risk for SIDS and may play a causal role in this syndrome. Most symptomatic infants can be adequately controlled with sympathomimetic or parasympatholytic therapy. Other cardiac arrhythmias occur at a rate similar to that in normal infants and are therefore unlikely to play a major role in SIDS.