A study of the reactivity of feeding vessels to arteriovenous malformations: correlation with clinical outcome.

Isolated segments from the feeding arteries to arteriovenous malformations (AVMs) from 24 patients were studied in vitro. In a perfusion chamber, isometric contraction of these arterial rings to various vasoactive substances was recorded and correlated with the following: spontaneous activity, spasm as seen in the operating room; radiographic evidence of ectasia preoperatively and postoperatively; and postoperative course. Of the 24 patients studied, four patients had nonreactive AVM nutrient vessels upon in vitro testing. In addition, these vessel segments displayed no spontaneous activity although all of the other vessels tested developed spontaneous activity while in the perfusion chamber. The patients with "unreactive vessels" had an increased incidence of postoperative edema and hemorrhage in the surrounding brain, consistent with the symptoms of normal perfusion pressure breakthrough. Thus, our study utilizes an in vitro technique to evaluate a specific segment of the AVM complex, the feeding vessel, which permitted us to assess abnormalities of reactivity in these vessel segments. This method may be useful for future evaluations of the pathophysiology of AVMs.