Which of the following mechanisms is responsible for the augmentation of coronary arterial blood flow and increased myocardial oxygen supply seen with the intra-aortic balloon pump?
a. The vacuum created in the aorta as a result of balloon deflation
b. Diastolic inflation with retrograde perfusion
c. Forward flow to the peripheral circulation
d. Inflation during systole to augment blood pressure
B
The blood volume in the aorta below the level of the balloon is propelled forward toward the peripheral vascular system, which may enhance renal perfusion. Subsequently, the deflation of the balloon just before the opening of the aortic valve creates a potential space or vacuum in the aorta, toward which blood flows unimpeded during ventricular ejection. This decreased resistance to left ventricular ejection, or decreased afterload, facilitates ventricular emptying and reduces myocardial oxygen demands.
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