Effects of intra-aortic balloon counterpulsation on coronary pressure in patients with stenotic coronary arteries.

BACKGROUND

The benefits of intra-aortic balloon pumping (IABP) usage reportedly occur through systolic unloading of the left ventricle and the augmentation of diastolic coronary flow. The aim of this study was to assess the change in intracoronary pressure distal to the coronary stenosis after the IABP by using an intracoronary pressure wire.

METHODS

Hemodynamic variables and intracoronary pressure data were measured in 16 patients requiring IABP for clinical indication (11 vessels with coronary stenosis and 5 normal vessels were enrolled). Coronary pressure was measured directly in each vessel with and without IABP support.

RESULTS

The diastolic aortic pressure during IABP increased compared with that without the IABP (97.9 +/- 11.7 vs 80.3 +/- 10.7 mm Hg, P < .01). The systolic aortic and intracoronary pressure during the IABP decreased (aortic pressure: 83.8 +/- 10.4 vs 95.9 +/- 11.3 mm Hg, P < .01, intracoronary pressure: 67.6 +/- 16.5 vs 76.2 +/- 20.4 mm Hg, P < .01). The diastolic distal coronary pressure (Pd) increased during the IABP in healthy coronary arteries (87.3 +/- 4.8 vs 72.1 +/- 10.3 mm Hg, P < .05). However, Pd in stenotic coronary arteries with the IABP did not increase statistically compared with those without the IABP (44.0 +/- 21.3 vs 42.8 +/- 17.9 mm Hg). There was a significant correlation between the change in Pd after IABP insertion and percent diameter stenosis calculated by quantitative coronary angiography (r2 = 0.51, P < .001).

CONCLUSIONS

In the presence of a critical coronary stenosis, the IABP does not increase the diastolic coronary pressure distal to the stenosis. Thus, the major effect of IABP on high-risk patients with severe coronary stenosis may relate to the reduction of oxygen demand by systolic unloading more than diastolic augmentation of the coronary flow.