Background: The present study was designed to determine whether there is a physiological explanation for the predisposition of patients with certain angiographic characteristics to haemorrhage from cerebral arteriovenous malformations (AVMs).
Methods: Intra-operative measurement of feeding artery pressure (FAP) and intravascular pressures in the draining venous system [draining vein pressure (DVP) and cranial sinus pressure (SP)] were performed for 30 AVM cases using direct puncture of the vessels. The correlation between pressures and previously described angiographic characteristics predisposing to haemorrhage were evaluated.
Findings: Small nidus size and only one draining vein increased the risk of haemorrhage. FAP and DVP are both inversely related to the number of draining veins and the size of the AVMs. DVP was significantly higher in AVMs with haemorrhage (23.1+/-8.7 mmHg) than in those without (13.5+/-4.4), as was FAP (58.6+/-12.8 as opposed to 38.7+/-4. 7) (p<0.05). Moreover, the difference between systemic blood pressure and the FAP with haemorrhagic AVMs (17.0+/-9.5 mmHg) was significantly lower than that in nonhaemorrhagic cases (33.7+/-5.5) (p<0.05). The pressure difference between the feeding artery and draining vein was not significant between the haemorrhagic and nonhaemorrhagic groups. There was no significant difference of SP between haemorrhagic and nonhaemorrhagic patients.
Interpretation: The present study suggests that a high DVP probably induced by high resistance in the venous drainage system, as well as a high FAP, may contribute to the development of haemorrhage from AVMs, and physiologically supports previous reports that small AVMs and AVMs with only one draining vein are susceptible to haemorrhage.