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Pressure autoregulation is intact after arteriovenous malformation resection
W L Young1, A Kader, I Prohovnik
1Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, New York, New York.
Neurosurgery
|April 1, 1993
Summary
Normal perfusion pressure breakthrough in arteriovenous malformation (AVM) patients is not caused by loss of cerebral blood flow autoregulation. Hemodynamic factors after AVM resection do not explain increased perfusion, suggesting pathological events are involved.
Area of Science:
- Neurology
- Neurosurgery
- Cerebrovascular Medicine
Background:
- Arteriovenous malformations (AVMs) can disrupt normal cerebral perfusion.
- Normal perfusion pressure breakthrough is a proposed mechanism for altered blood flow in AVM patients.
- Previous studies suggested a loss of autoregulation contributes to this phenomenon.
Purpose of the Study:
- To directly test the hypothesis that loss of autoregulation causes normal perfusion pressure breakthrough.
- To investigate the hemodynamic changes in cerebral blood flow (CBF) during and after AVM resection.
Main Methods:
- Cerebral blood flow (CBF) was measured using the xenon-133 method in 25 patients undergoing AVM resection.
- Measurements were taken before resection, after resection at baseline blood pressure, and after induced hypertension (phenylephrine).
- Cerebral autoregulation was assessed by observing CBF response to induced changes in mean arterial pressure.
Main Results:
- AVM resection significantly increased CBF in the adjacent hemisphere (30 +/- 2 vs. 25 +/- 1 ml/100g/min).
- Increased mean arterial pressure after resection did not further elevate CBF, indicating preserved autoregulation.
- Two patients with complications (hemorrhage, brain swelling) had the highest CBF increases but maintained autoregulation.
Conclusions:
- Preserved cerebral autoregulation after AVM resection refutes a hemodynamic mechanism for increased hemispheric perfusion.
- Pathological events, rather than loss of autoregulation, appear linked to increased perfusion post-AVM resection.
- Further research into pathological mechanisms underlying altered cerebral perfusion in AVM patients is warranted.