EFFECTS OF INTRAAORTIC BALLOON COUNTERPULSATION ON CAROTID-ARTERY BLOOD-FLOW

Background The intraaortic balloon pump has been shown to improve card iac output and diastolic coronary flow. Animal studies with balloon co unterpulsation have shown variable effects on carotid and cerebral blo od flow. We investigated the effects of counterpulsation with the intr aaortic balloon pump on blood flow in the common carotid artery in hum an beings. Methods and Results We studied 14 patients who had on intra aortic balloon pump placed For clinical indications; 9 were hypotensiv e (4 in the setting of an acute myocardial infarction and 5 immediatel y after cardiac surgery). Five patients required counterpulsation afte r undergoing complicated coronary angioplasty. Common carotid artery b lood flow was assessed with carotid Duplex scanning both with and with out 1:1 balloon augmentation. We found no net increase in the total bl ood flow in the common carotid artery with intraaortic balloon counter pulsation. This result occurred despite a significant mean increase in both the peak flow velocity and flow velocity integral of the augment ed diastolic flows by 160% and 78%, respectively. Total flow did not c hange because an early systolic reversal of blood flow was seen only w ith balloon augmentation, which negated the augmented diastolic flow. Conclusion Despite a significant augmentation in diastolic blood flow with balloon counterpulsation, no increase occurred in total carotid a rtery blood flow. This appeared to be caused by improper timing of bal loon deflation. This could result in no improvement in cerebral blood flow with intraaortic balloon pump counterpulsation in critically ill patients.