Intra-aortic balloon counterpulsation pump therapy: a critical appraisal of the evidence for patients with acute myocardial infarction

Pressure and flow-volume distribution associated with intra-aortic balloon inflation: an in vitro study

The intra-aortic balloon pump (IABP) is the most widely used cardiac assist device, whose main benefits are augmentation of coronary flow and reduction of left-ventricular afterload. The aim of this study is to investigate the pressure and flow-volume distribution associated with balloon inflation. We hypothesize that in order to displace fluid on both sides of the balloon, a pressure locus must be present along the balloon during inflation. In vitro experiments were performed in two positions, horizontal and angled, using four balloon sizes: 25, 34, 40, and 50 cc. Along and on both sides of each balloon, we measured pressure, flow rate, and calculated flow velocity, volume displacement, wave intensity and energy. A pressure locus was found at the center of each balloon and the average flow volume displaced toward the tip at the horizontal position was about 57% of the balloon volume. In the angled position, the location of the pressure locus was less obvious and average volume displacement toward the top end of the balloon was reduced to 45%. These results confirm the existence of a pressure locus at the center of each of the balloons we tested. Because a clear reduction in flow volume was observed at the angled position, these results may have clinical implications as most patients using IABP in the intensive care units are nursed in semirecumbent position.

Computed tomography appearance of an intra-aortic balloon pump: a potential pitfall in diagnosis

The case of a patient with an indwelling intra-aortic balloon pump (IABP) who underwent computed tomography (CT) to rule out mesenteric ischemia is reported. Three-dimensional reconstruction revealed regularly spaced air-fluid levels within the aorta. Intra-aortic balloon pump function is reviewed, and it is shown that its artifactual appearance on CT results from the phase difference between the cardiac cycle and gantry speed. Recognizing and understanding the appearance of an IABP is important so as not confuse it with intra-aortic air, which suggests ischemia.