Hemodynamic Effects of Quantitatively Varied Experimental Aortic Regurgitation

A canine preparation was devised in which aortic regurgitant flow could be acutely produced, metered and controllably varied. Aortic regurgitant flows in excess of the dog's resting cardiac output resulted in a marked decrease of effective cardiac output, a substantial rise of peripheral resistance and left ventricular end-diastolic pressure, and a marked depression of the left ventricular function curve, with little change in the mean left atrial pressure. When mitral regurgitation was added to aortic regurgitation, effective cardiac output, stroke work and left ventricular end-diastolic pressure fell, while left atrial pressure rose.