Abnormal heart rate response during newborn sucking behavior study: subsequent sudden infant death syndrome with cardiac conduction abnormality.

This report concerns a four-month-old white female infant who exhibited abnormal feeding behavior and EKG irregularities during a newborn sucking behavior study. The immediate post-birth history showed an irregular heart rate on two occasions, but a cardiac consultation elicited no unusual findings. During sucrose sucking conditions, the heart rate increased with a beat-to-beat variation of 50 beats per minute, noted to be due to premature atrial beats. At 39 days, an EKG showed a marked sinus tachycardia of 156, a PR interval of 0.08, QRS of 0.05 and a QT of 0.26. The infant was diagnosed as a sudden infant death syndrome (SIDS) following an unexpected death at home. Subsequent cardiac pathology revealed an anomalous tract between the right atrium and the atrioventricular (AV) bundle which formed an extensive bypass of the AV node (atrio-His tract), and two accessory AV connections between the left atrium and posterior left ventricle. These findings are consistent with the Wolff-Parkinson-White syndrome type A. Only further studies can determine whether such abnormal feeding behavior with EKG irregularities can be used to identify infants who are at high risk for sudden death.