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Heart rate (HR) has been characterized as an important cardiovascular parameter that affects acute hemodynamic performance of intra-aortic balloon counterpulsation (IABC). However, the effect of HR on hemodynamics during mechanical assistance by the IABC has neither been clarified nor quantified. We sought to evaluate the relationship between IABC and HR and also to examine whether there is a range of HR with optimum hemodynamic response to IABC.Methods. 20 patients (14 males - 6 females, mean age 64.4±11.4 years) with post-infarction cardiogenic shock undergoing IABC treatment were evaluated. Hemodynamics were recorded for each patient once per day during the assistance period; 131 measurements were taken and thus a wide range of heart rates was obtained (64–141 bpm). The following changes in aortic pressures were used to evaluate acute IABC performance on: a) the maximal increase of diastolic aortic pressure induced by IABC and b) the reduction in systolic and end-diastolic aortic pressure.Results. Non-linear regression analysis and analysis of variance revealed that a significant correlation exists between IABC performance indices and heart rate. At HR<80 bpm, IABC performance tended to be reduced, whereas the increase in HR above 110 bpm resulted in a significant reduction of all IABC performance indices. In contrast, IABC operating at 80–110 bpm resulted in optimum hemodynamic performance. In conclusion, the effect of heart rate on IABC performance is non-linear indicating that IABC may be more effective when operating within 80–110 bpm.

Data concerning the effect of arterial compliance (AC) on hemodynamics during intra-aortic balloon counterpulsation (IABC) are lacking. This study examines the effect of AC on acute hemodynamics induced by IABC in 15 patients with post-infarction cardiogenic shock. AC was estimated by aortic pulse wave analysis using the reflection time index (RTI). Measurements were obtained once per day during IABC. The % reduction in systolic aortic pressure (ΔSAP), end-diastolic aortic pressure (ΔEDAP) and the peak aortic diastolic augmentation (PADA) were used as performance indices of IABC; 107 sets of measurements were obtained. Multivariate analysis indicated an independent association of each IABC performance index with AC (p<0.05). A high AC group (RTI≤20.6%, n=40) and a low AC group (RTI>20.6%, n=67) were obtained. ΔSAP, ΔEDAP and PADA were significantly higher in the low AC group by almost 75%, 54.6% and 11,3% (p<0.03), while arterial blood pressure did not significantly differ. Arterial compliance is an independent factor affecting hemodynamics during IABC. RTI values higher than 20.6% may predict a better acute hemodynamic response to IABC.

This experimental study compares the effect of catecholamine infusion to the effect of intraaortic counterpulsation (IABP) while initiating intraventricular balloon pumping (IVBP) in the fibrillating heart. In 12 dogs IVBP started immediately after the induction of ventricular fibrillation. Intravenous adrenaline or noradrenaline (at a progressively increasing infusion rate until the systolic aortic blood pressure was 120 mm Hg) was interchanged with IABP. The systolic aortic pressure, the aotic flow and the mean left atrial pressure were, respectively, 120.4 ± 0.5 mm Hg, 42 ± 4 mlkg-1min-1and 18.7 ± 1.2 mm Hg (x ± SEM) ten min after initiating catecholamine infusion and 97 ± 5 mm Hg (with a 131 ± 4 mm Hg diastolic wave), 69.6 ± 4 mlkg-1min-1and 16 ± 1.5 mm Hg ten min after initiating IABP. The difference in aortic flow was significant (p<0.001). The results indicate that a better aortic flow may be obtained by combining IVBP and IABP than IVBP and vasoconstrictive agents in the fibrillating heart. If IVBP, IABP and catecholamines are combined, both AF and AP may increase.