The Hemodynamic Effects of External Counterpulsation in Patients with Recent Stroke.

摘要

External counterpulsation (ECP) is a noninvasive method used to improve the perfusion of vital organs, which may increase cerebral blood flow and/or its collateral circulation resulting in possible benefits to ischemic stroke patients as shown in our previous studies. We aim to explore the hemodynamic effects of ECP on the cerebral circulation in patients with recent ischemic stroke. First, we investigated the changes in flow velocities in both the infarction affected side as well as the contralateral side during ECP, which may be regarded as part of the collateral circulation. Second, we studied the dynamic augmentation effects of ECP compared with the well established vasomotor reactivity. Third, we used external counterpulsation to assess the cerebral autoregulation on patients receiving cerebral angioplasty of stenting.;In this study, we recruited recent ischemic stroke patients with large artery occlusive disease receiving ECP treatment. We monitored their cerebral blood flow velocities of bilateral MCAs using transcranial Doppler (TCD). We found the mean flow velocities during ECP (150mmHg) increased significantly on ipsilateral side and contralateral side when compared with baseline velocities, but there was no increase difference between the two sides when compared with each other. Peak diastolic velocities significantly increased on ipsilateral side (78.70%, p diastolic velocities significantly increased on ipsilateral side (78.70%, p<0.001) and contralateral side (83.10%, p<0.001), compared with baseline end diastolic velocity. No difference was found between two side on the increase of peak diastolic augmentation.;The hemodynamic effect during ECP on cerebral blood has not been quantified. We proposed a measurement of cerebral augmentation index (CAI) to evaluate the augmentation effect induced by ECP. It may be a measure of how the brain accommodates to elevated blood pressure and flow diversion. It may also be considered as a form of vaso-reaction. We compared CAI to a well-established measurement of vasomotor reactivity, breathholding index (BHI). We performed ECP treatment and breathholding test combined with TCD monitoring on ischemic stroke patients with large artery occlusive disease and good temporal window. We aimed to explore the correlation between the augmented hemodynamic effect of ECP and cerebral vasomotor reactivity.;We analyzed our ECP registry of acute ischemic stroke patients with cerebral large artery stenosis who underwent ECP therapy at the Prince of Wales Hospital. A standard treatment protocol consisted of 35 daily ECP sessions (each session one hour). We included 155 patients who completed at least 10 sessions of ECP and had 3 months follow up data. Patients were divided into different outcome groups according to mRS. We compared the differences in the two groups in terms of demographics, medical history and ECP treatment duration time.;We did a pilot study to research the augmentation effect of ECP on internal carotid artery (ICA) from carotid TCD monitoring with a novel neck frame. Comparing the CAI of MCA with that of ICA, we aimed to investigate if any correlations exist between augmentations observed from two vessels. Further test the feasibility of ICA monitoring.;In summary, the extent of cerebral blood flow augmentation during ECP in patients with recent stroke appears to be the same in the infarct territories when compared with contralateral side. These findings suggest that potentially circulation may be enhanced to improve the collateral blood supply of ischemic territories both from the infarct ipsilateral side and contralateral side. Dynamic augmentation effects as measured by CAI were different from the well established vasomotor reactivity. CAI is a measure of how well the brain accommodates blood flow augmentation, independent of vasomotor reactivity. Evaluated by CAI, stenting of intracranial atherosclerosis may improve the cerebral autoregulation and ability for the ischemic brain to accommodate flow augmentation in long term. 150mmHg appears to be the optimal and safe pressure to be used to inflate the cuff in the ECP in order to increase cerebral blood flow. Further increase in pressure does not increase cerebral blood flow velocity. The duration of ECP therapy is found to be an important predictor for stroke recovery on ECP-treated acute ischemic stroke patients, in addition to the well-known prognostic factors such as admission NIHSS and blood pressure. This series of studies elucidate the important mechanisms of the potential benefits of ECP on stroke patients. (Abstract shortened by UMI.).