Right ventricular hypertrophy was produced by chronic constriction (banding) of the pulmonary artery in the dog. Right ventricular muscle mass increased by 40% in 6 to 12 weeks after banding. Maximal work performance of this ventricle also increased; at 12 weeks the mean was 175% more than that of the normal right ventricle. It was concluded that, per unit of gross myocardial mass, the work performance of the hypertrophied right ventricle of the dog was no less than that of the normal right ventricle.
Two cases in which large intramural ventricular cardiac fibromas were successfully removed from children are reported. In one the fibroma was principally septal, and in the other it lay in the free wall of the left ventricle. These are the second and third such operations reported. A review of these two cases plus 34 other reported cases of cardiac fibroma indicates that a primary mural tumor of the heart should be suspected in patients, particularly children, with unexplained cardiac failure, unexplained cardiac dysrhythmia, intracardiac calcifications, irregular shadows on roentgenograms, or unexplained newly developing cardiac symptoms and murmurs. Angiocardiography is the best way of confirming the diagnosis. In view of the potential hazard of these tumors, their surgical removal should be undertaken, and this experience indicates that even very large and extensive intramural ventricular tumors may be removed successfully.