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Infants with apparent life threatening events. Cardiac rhythm and conduction
P K Woolf1, M H Gewitz, T Preminger
1Division of Pediatric Cardiology, New York Medical College, Valhalla 10595.
Insights
Sudden Infant Death Syndrome (SIDS) risk may be linked to cardiac dysrhythmias. Holter monitoring in infants with Apparent Life Threatening Events (ALTE) revealed frequent, though mostly insignificant, heart rhythm abnormalities.
Area of Science:
- Pediatric Cardiology
- Cardiac Electrophysiology
- Neonatal Research
Background:
- The link between cardiac dysrhythmias and Sudden Infant Death Syndrome (SIDS) remains unclear.
- Infants experiencing Apparent Life Threatening Events (ALTE) have been reported to have significant dysrhythmias.
Purpose of the Study:
- To investigate cardiac rhythm and conduction in infants at risk for SIDS using Holter monitoring.
- To characterize the prevalence and significance of dysrhythmias in infants with a history of ALTE.
Main Methods:
- 24-hour continuous Holter electrocardiograms were performed on 100 full-term, healthy infants with ALTE.
- Cardiac rhythm, QTc interval, and various types of dysrhythmias were analyzed.
Main Results:
- 62% of infants exhibited one or more dysrhythmias.
- Premature ventricular depolarizations (PVD) occurred in 25%, and 30% had prolonged QTc intervals.
- Sinus node irregularity was observed in 39%, with 2% requiring treatment for sinus node dysfunction. No significant arrhythmias requiring therapy were noted.
Conclusions:
- Holter monitoring reveals a high incidence of cardiac dysrhythmias in infants with ALTE.
- While most dysrhythmias are clinically insignificant, findings support theories of cardiac electrical instability in some at-risk infants.
- Holter monitoring provides valuable data for understanding the cardiac etiology of SIDS.
Abstract:
The role of cardiac dysrhythmias in the pathogenesis of Sudden Infant Death Syndrome (SIDS) is uncertain, but there have been several reports of infants with Apparent Life Threatening Events (ALTE) due to significant dysrhythmias. To further characterize the cardiac rhythm and conduction of these "at-risk for SIDS" infants, we performed 24-hour continuous (Holter) electrocardiograms on 100 full term, healthy infants with ALTE. Sixty-two patients (62%) had one or more dysrhythmias on Holter monitor. Twenty-five patients (25%) had premature ventricular depolarizations (PVD), including five with couplets. Thirty (30%) had QTc greater than 2 SD above the mean, and, of these, 40 percent had PVD's. Fifteen (15%) had premature atrial depolarizations and 39 (39%) had evidence of moderate or marked sinus node irregularity. There was no prexcitation, supraventricular tachycardia, ventricular tachycardia, or atrioventricular block. Two patients with marked sinus node dysfunction were treated with propantheline and did well. All patients were monitored at home, with no deaths or clinically significant dysrhythmias on follow-up (1-32 months (mean = 18]. In summary, when Holter monitoring was performed, a high incidence of dysrhythmia was found in infants with ALTE. Most dysrhythmias were clinically insignificant. The incidence of ventricular dysrhythmias and long QTc are consistent with previously advanced theories of cardiac electrical instability in some of these patients, but no patient with ventricular dysrhythmias required therapy. The incidence of sinus node dysfunction requiring therapy was 2 percent. Although Holter monitoring of infants with ALTE only infrequently determines therapy, it may provide data linking theories of cardiac etiology of SIDS with actual clinical events.