Abstract
Evaluation of preoperative hemodynamics and vascular reactivity of arteriovenous malformations supplying arteries (feeders), namely the middle Cerebral artery and dilated cerebral basal arteries such as the anterior choroidal artery and perforating arteries, was performed using transcranial Doppler ultrasound. Twenty normal subjects and 10 patients with angiographically proven cerebral arteriovenous malformations (AVM) were studied. Time mean velocity (Vm), peak systolic velocity (Vs) and end diastolic velosity (Vd) were measured by transcranial Doppler ultrasound (TC2-64, EME Co.) at bitemporal portions. The pulsatility index [PI=(S-D)/M] and the Resistance index [R=(S-D)/S] were calculated. To see pCO2 reactivity, hyperventilation was done (deep breath: twice/5 sec. for 30 sec.). In patients with AVMs, blood velocity of feeders increased remarkably up to 150cm/sec (Vm) and 190 cm/sec (Vs) individually, which were more than two times the velocities measured for normal subjects. Both PI and R decreased significantly. Reactivity against hypocapnia also showed significant decrease. V(D) (velocity at sick side)/V(N) (velocity at normal side), Vd/Vs revealed that hemodynamic changes more clearly. These changes seemed to be more remarkable in patients with high blood flow velocity. According to the relationship between the artery and the nidus, cases were divided into three groups, namely mainly (Group A), partially (Group B) and poorly (Group C) angioma supplying arteries. These hemodynamic changes were remarkable in Group A. Postoperatively, these changes, including pCO2 reactivity, recovered to the normal range.
Moreover, wave forms were analysed by FFT analyser (FAE 2000, Kikusui Elect. Comp.) in 40 normal subjects and in 5 patients with AVMs. Analysis of the wave forms revealed characteristic findings in all of the patients, namely disappearance of the groove which is commonly seen at 3 to 7 KHz range in normal adults. These wave forms resembled those of a child.
As a conclusion, characteristic changes were recognized in hemodynamics and pCO2 reactivity of feeders, especially on mainly angioma supplying arteries. In such cases, care should be taken to guard against the normal perfusion pressure breakthrough phenomenon during surgery. Analysis of the wave forms of patients revealed characteristic changes; thus such analysis seems useful for diagnosis and analysis of the hemodynamics of AVMs.
