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Middle cerebral artery occlusion in presence of low perfusion pressure increases infarct size in rats
H Sillesen1, M Nedergaard, T Schroeder
1Department of Vascular Surgery, Rigshospitalet, University of Copenhagen, Denmark.
Abstract:
A model was set up in order to evaluate the importance of hemispheric perfusion pressure when the middle cerebral artery (MCA) is occluded in anaesthetized rats. In 6 animals the internal carotid artery (ICA) was occluded prior to ipsilateral MCA occlusion; in 17 animals the MCA only was occluded; 6 animals underwent the same preparation, but the vessels were left unoccluded. Four days after surgery the infarct volume was measured with a computerized image analyser. The infarcted areas were significantly larger in the ICA + MCA occluded group compared with the MCA occluded group (p less than 0.005), which in turn had larger infarcts than the sham-operated animals (p less than 0.001). These results indicate that patients with hypoperfusion, due to severe ICA stenosis and impaired collateral blood supply, are at higher risk of developing major stroke, when embolism into a cerebral artery occurs, as compared to patients with no, or only minor, reduction in hemispheric perfusion pressure.
Insights
Reduced hemispheric perfusion pressure, caused by internal carotid artery (ICA) stenosis, significantly increases stroke risk. This heightened risk is evident when an embolism affects the middle cerebral artery (MCA).
Area of Science:
- Neuroscience
- Cerebrovascular Research
- Stroke Pathophysiology
Background:
- Hemispheric perfusion pressure is critical for maintaining adequate brain blood flow.
- Occlusion of major cerebral arteries, like the middle cerebral artery (MCA), can lead to ischemic stroke.
- Collateral blood supply plays a vital role in mitigating stroke severity following arterial occlusion.
Purpose of the Study:
- To evaluate the impact of reduced hemispheric perfusion pressure on stroke development.
- To determine the significance of internal carotid artery (ICA) status in MCA occlusion-induced stroke.
- To model the risk associated with hypoperfusion and subsequent cerebral artery embolism.
Main Methods:
- Anesthetized rats were used to establish experimental stroke models.
- Groups included: ipsilateral internal carotid artery (ICA) and middle cerebral artery (MCA) occlusion; MCA occlusion only; and sham-operated controls.
- Infarct volume was quantified using a computerized image analyzer four days post-surgery.
Main Results:
- The ICA + MCA occluded group exhibited significantly larger infarct volumes compared to the MCA occluded group (p < 0.005).
- The MCA occluded group showed significantly larger infarcts than the sham-operated animals (p < 0.001).
- Reduced hemispheric perfusion pressure exacerbated stroke severity in a rat model.
Conclusions:
- Patients with hypoperfusion due to severe ICA stenosis and poor collateral supply face a higher risk of major stroke.
- Embolism into a cerebral artery in the context of reduced perfusion pressure leads to more severe outcomes.
- Maintaining adequate hemispheric perfusion pressure is crucial for stroke prevention and mitigating infarct size.