Discussion

DR. BERNADINE H. BULKLEY: This &month-old female was unwell from the time of birth. Initially she showed nonspecific signs of poor slope of Iere left feeding and irritability. The cause of her failure to thrive did not become apparent, however, until 2 months of age when she was noted to have a heart murmur and unexplained cardiomegaly. Echocardiogram suggested left ventricular hypertrophy without evidence of asymmetric septal hypertrophy, and Thallium 201 myocardial perfusion imaging, which may also be a useful noninvasive method for detection of asymmetric septal hypertrophy,’showed only concentric hypertrophy with a normal to small-sized left ventricular cavity. Cardiac catheterization revealed essentially normal right and left ventricular pressures, and no evidence of intracardiac shunting, valve abnormalities, or congenital malformation. She did have an increased stroke volume for size, and an increased ejection fraction of 70 per cent, suggesting a hypertrophic cardiomyopathy. Biventricular angiograms also showed ventricular hypertrophy and a small left ventricular cavity. Thus, congenital aortic stenosis or atresia were ruled out by the catheterization studies, as was the possibility of an anomalous left coronary artery which might have been suggested by the elevated cardiac enzymes. The lack of ventricular dilatation and good ventricular function elimi-