Reperfusion in acute ischemic stroke

Project: ResearchClinical research


To study the time window of recanalization in stroke patients with embolic occlusions or stenoses of the intracranial vessels in relation to the development of collateral blood flow.
To evaluate the importance of body temperature and blood pressure for the temporal pattern of recanalization, collateral blood flow, and clinical improvement.
Study design Prospective observational study comparing ultrasound, radiological and clinical parameters among stroke patients at the acute stage.

Working plan
Examinations by ultrasound are performed within 12 hours after onset of stroke symptoms on consecutive stroke patients with occlusion or high-grade stenosis of the middle cerebral artery (MCA) and followed – up at 4, and 24 hours. The recanalization of the MCA will be monitored at the time points according to previously published criteria (3). Collateral flow through the anterior and posterior cerebral artery will be assessed by measuring the peak systolic velocities in the anterior and posterior cerebral artery according to standardized data (4). The increase in flow velocity of the affected side will be compared to the unaffected side and calculated as percent increase at the pre-specified time points. This will allow measuring the activation of leptomeningeal collateral flow indirectly and is a predictor of stroke volume and outcome (5). Patients will be sub-divided in collateral flow negative vs. positive at the different time points. Body temperature and blood pressure will be measured at the different time points and correlated to clinical outcome.
CT Perfusion angiographies will be performed within 24 h after onset of stroke symptoms on all included patients. Cerebral perfusion in patients with acute stroke will be assessed by evaluating cerebral blood volume, cerebral blood flow, and mean transit time. CTP examinations with be correlated with final CT at seven days and clinical outcome.
A subgroup of these patients will be examined by MRI brain using ADC mapping and flair sequences within 12 hours. This will allow to study the effects of collateral flow on the final infarct size in detail.

Outcome will be assessed at admission (within 12 hours after stroke onset) according to the National Institute of Health stroke Scale (NIHSS) and at 4, and 24 hours, and after 7 days.

Five patients have been included, recruitment of collateral blood flow was increasing under the first 24 hours at the same time as the occlusion or high-grade stenosis in the MCA recanalizes. These are exciting results, because it could be shown that both recanalization and recruitment of collateral blood flow improve outcome, but intracerebral flow dynamics in the first 24 hours have not been studied yet. The aim is to achieve full data of at least 20 patients.
Clinical implementation
Reperfusion of the brain penumbra plays a major role for the prognosis of stroke patients at the acute stage. It is dependent on arterial blood flow supply, collateral blood flow, blood pressure and additional homeostatic parameters. In this study parameters of reperfusion like recanalization and collateral blood flow will be assessed and correlated to outcome after stroke in order to understand mechanisms and the temporal pattern of reperfusion. Recently time windows had been extended in selected cases for example "wake-up" strokes and strokes in the posterior circulation. The majority of patients (>60%) does not reach the hospital in the time windows for reperfusion therapies.
These patients benefit from improved monitoring and selection criteria. The study helps to understand parts of the basic pathophysiology of mechanism of cerebral blood flow in the first 24 hours after stroke.
Short titleReperfusion in stroke
StatusNot started