Which of the following are physiologic benefits of intra-aortic balloon counterpulsation to the ischemic ventricle?

B. Afterload reduction.

C. Coronary blood flow enhancement.

D. Decreased ventricular end-diastolic pressure.

DISCUSSION: In general, preload relates to the volume of blood or fluid presented to the left ventricle. Although wall tension does increase with increased volume, Starling properties are called forth for added efficiency. Preload is controlled by volume status as well as capacity of the venous system. The effects of balloon counterpulsation on cardiac preload are minimal and secondary to other changes. As the balloon collapses in the aorta, the absence of the balloon volume, or “abyss,” creates a decrease in ventricular afterload. In effect this decreases ventricular wall tension, reducing myocardial oxygen consumption significantly. During counterpulsation, the intra-aortic balloon inflates in diastole, elevating coronary perfusion pressure significantly. Maximal coronary artery perfusion occurs in this part of the cardiac cycle. Thus, ischemic ventricles benefit especially from balloon pumping. The balloon pump does not directly decrease the left ventricular end-diastolic pressure. However, in ventricles failing from ischemia the combination of afterload reduction and improved coronary blood flow usually augments cardiac function, producing decreased cardiac filling pressure or left ventricular end-diastolic pressure.