An acardiac infant: the extreme form of the twin-twin transfusion syndrome.

A description of the pathologic and clinical findings in a twin with twin-to-twin transfusion syndrome is given. One of them died immediately after birth, with the autopsy revealing the histologic absence of the myocardium. The surviving infant presented with short term heart failure and with persistent left ventricular hypertrophy over 6 months. The circulatory changes in the twin-to-twin transfusion syndrome can result in complete myocardial involution in one and an unexpectedly long compensatory left ventricular hypertrophy in the other infant. Caution is advised in order to avoid misdiagnosing hypertrophic cardiomyopathy. In such a case a longer follow-up period is recommended.