Cross-sectional echocardiographic observation of the short axis views of the left ventricle in hypertrophic cardiomyopathy.

Short axis views of the left ventricle were studied in 68 patients with hypertrophic cardiomyopathy (HCM) and 20 healthy persons using cross-sectional echocardiography. Configurations of the short axis view of the left ventricular cavity at the level of the papillary muscles in HCM were classified into 2 types, dumbbell and mushroom, which were formed by the position of papillary muscles. Antrior dislocation of the papillary muscles was seen in the dumbbell type, and marked hypertrophy of the papillary muscles in the proper position was seen in the mushroom type. Dumbbell shape (50 patients) was observed in the patients with marked hypertrophy in the basal protion of interventricular septum. Mushroom shape (18 patients) was seen in the patients with hypertrophy around the apex of the heart except for in a few patients. Areas of the papillary muscles (AP) and the left ventricular cavity (ALV) were measured and AP/ALV + AP ratio was calculated. The AP/ALV + AP ratio in HCM was significantly larger than that in the healthy persons, but no difference was seen between these 2 groups of HCM. It should be noted that the position of the hypertrophied papillary muscles is closely related to the distribution of hypertrophy in HCM.