The hemodynamic response to intra-aortic balloon counterpulsation in patients with cardiogenic shock complicating acute myocardial infarction.

Sixteen patients with cardiogenic shock complicating acute myocardial infarction underwent serial hemodynamic studies during intra-aortic balloon counterpulsation (IABC) at an assist frequency of 1:1. Significant increase was noted during the first 12 hours of IABC in the systemic artery peak diastolic pressure (assisted), cardiac index, stroke index, and stroke work index. During the second 12 hours further significant improvement was noted in the latter three parameters and, in addition, the systemic artery systolic pressure increased significantly. The pulmonary wedge pressure fell as did the total systemic resistance (TSR) during the first 24 hours of IABC. Patients found to be balloon independent after reduction in balloon assist frequency demonstrated significantly greater increase in systemic artery peak diastolic pressure during the first 12 hours of IABC than did those patients found to be balloon dependent. Likewise, the improvement noted in CI, SI, and SWI during the second 12 hours of IABC was of greater magnitude in balloon-independent than in balloon-dependent patients. The data suggest late hemodynamic deterioration after 48 hours of IABC. It is concluded that IABC is effective in improving the deranged hemodynamics of cardiogenic shock. Maximum response is noted between 24 and 48 hours. It is suggested that patients who are balloon independent may be distinguished from those who are balloon dependent by the hemodynamic response within the first 24 hours of IABC.