Experimental and Clinical Studies on the Effect of Intra-Aortic Balloon Pumping for Cardiogenic Shock Following Acute Myocardial Infarction

The effect of intra-aortic balloon pumping (IABP) on cardiogenic shock following acute myocardial infarction was studied experimentally and clinically. Effects of IABP on hemodynamic and electro-cardiographic changes were studied with cardiogenic shock which was produced by multiple ligation of the coronary artery in dogs. Consequently, the hemodynamics as well as the ECG could be improved by diastolic augmentation and systolic unloading during IABP. But, these favorable effects of IABP were not seen in dogs whose infarcted area involved more than 50% of the free wall of the left ventricle. These facts were seen clinically in three autopsied cases. IABP was also attempted in dogs with complications such as ventricular septal defect (VSD) and mitral regurgitation (MR) following acute myocardial infarction, and significant improvement was obtained by IABP. No effects of IABP were seen in these series, however, when the value of the pulmonary-to-systemic flow ratio was over 4.5 in the VSD group and the mean left atrial pressure was more than 30 mmHg in the MR group. Clinically, IABP was employed in 16 patients with cardiogenic shock secondary to acute myocardial infarction. Six (37.5%) were weaned from IABP. It can be concluded that IABP is effective in improving hernodynamics as well as the ECG.