Cardiac Performance of Hypertensive Aorta-Constricted Rabbits

A heart-lung preparation with flow limited to the coronary vessels was used to study cardiac performance 4 to 120 days after severe constriction of the abdominal aorta in rabbits. Cardiac performance was evaluated by finding the maximum mean arterial pressure against which the heart could pump. Cardiac performance began to exceed the normal, range by the second or third post operative week and was well above normal after the first month. A high cardiac performance was not necessarily associated with marked ventricular hypertrophy. Animals died of heart failure within the first month, and all had developed a much more rapid rate of blood pressure increase than those that survived without signs of decompensation. We conclude that the basic cause of heart failure after severe aorta constriction is a rapid rise in arterial pressure which exceeds the rate at which the heart develops an improved performance.