Intra-Aortic Balloon Counterpulsation for the Treatment of Ischemic Stroke

Abstract

Colloid volume expansion has been shown to increase cerebral blood flow to ischemic brain in an animal stroke model and improve recovery in patients. It is, however, potentially hazardous to use in older patients because of frequently associated cardiovascular disease. Intra-Aortic Balloon Counterpulsation might reduce the risks of using volume expansion therapy in the elderly patient. This study was designed to see if Intra-Aortic Balloon Counterpulsation (without volume expansion), in an animal with a normal heart, would increase cerebral blood flow and EEG activity in the ischemic brain. Unilateral cerebral ischemia was produced in baboons (n = 9) after right middle cerebral artery occlusion. A 12 ml intra-aortic balloon catheter was introduced into the descending aorta via the femoral artery prior to middle cerebral artery occlusion. The balloon was positioned distal to the origin of the left subclavian artery and following middle cerebral artery occlusion was inflated with each R wave on the ECG. Cardiac output, cerebral blood flow (by Hydrogen wash-out), computer-mapped EEG, and hemodynamic data were collected prior to middle cerebral artery occlusion and following occlusion both before and during counterpulsation. Intra-Aortic Balloon Counterpulsation produced a significant increase in pulse pressure from 54.7 ± 21 to 70.6 ± 33 mmHg (p = .043). No significant change was seen in cardiac output, mean arterial pressure, or cerebral blood flow. Although the computer- mapped EEG improved and the right (ischemic) hemisphere cerebral blood flow did increase slightly from 16.9 ± 6.5 to 18.3 ± 8.3 ml/100 gm/min, the cerebral blood flow changes were not significant (p=.295). It is possible that the desired increase in cerebral blood flow was not achieved partly because the animals were only 3-4 years old and were difficult to stroke. We believe that there is merit to a follow-up study in older primates with colloid volume expansion where Intra-Aortic Balloon Counterpulsation is used to protect the heart from the deleterious effects of volume expansion and where the cardiac effects of volume expansion and counterpulsation are quantified. Perhaps volume expansion with Intra-Aortic Balloon Counterpulsation will be safer and more effective than either treatment modality alone. (All data reported as mean ± standard deviation)