The contractile function of right ventricular papillary muscles from normal cats and cats in which the pulmonary artery had been constricted for 6 or 24 wk was examined. Acute pulmonary artery constriction reduced cross-sectional area by an average of 70%, resulting in a 30% mortality from congestive heart failure, all such deaths occurring within the first 3 wk after banding. The increase in right ventricular mass in animals surviving for 6 or 24 wk was similar, averaging 70%. No banded animals had evidence of congestive heart failure at the time of sacrifice, and cardiac output and right atrial pressures were similar to those in control animals.
John F. Williams Jr., Ralph D. Potter