Severe Pulsus Alternans Associated with Primary Myocardial Disease in Children

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Abstract
Five children, including two siblings, with clinically similar primary myocardial disease, were studied. One of the siblings expired 3 years after the onset of symptoms, and autopsy showed features of "cardiovascular collagenosis (endocardiomyopathy)." Moderate-to-severe pulsus alternans was present in all cases and persisted even after control of cardiac failure and return to moderate physical activity. No electrical alternans or bigeminy was observed. Cardiac catheterizations were performed on all patients. Left ventricular volume was radiographically determined in the siblings. Left ventricular end-diastolic volume was calculated as greater, and end-systolic volume smaller, for large beats as compared with small beats. Though alternating, end-diastolic volume was abnormally large, preceding both small and large beats. End-diastolic pressure alternated in the same way. Beat to beat (R-R) interval, alternating by as much as 0.09 second, was equalized by pacing in the right atrium and right ventricle, with persistence of pulsus alternans to a lesser degree. Isovolumetric contraction time was prolonged preceding small beats in spite of the large preceding end-diastolic volumes. The data appear to be consistent with Starling's law but suggest that impaired contractility, possibly due to alternate deletion of contractile elements, is an additional etiological factor.