A Correlation of Catecholamine and Vasoactive Peptide Release With Hemodynamics in Patients Undergoing Resection of Arteriovenous Malformations

Abstract

Control of blood pressure can be a problem for intracranial procedures. To investigate the relationship between hemodynamic variables and endogenous vasoactive substances, we studied patients undergoing resection of arteriovenous malformations (AVMs). This was a nonrandomized, prospective study of six patients who had resection of an intracranial AVM and six patients who had clipping of an intracranial aneurysm (ICA) that had not bled. Operative and postoperative blood pressure was controlled with sodium nitroprusside. Heart rate (HR), mean arterial pressure, pulmonary capillary wedge pressure, and cardiac index (CI) were measured after induction of anesthesia; before, during, and after hypotensive anesthesia; immediately postoperatively; and at 12, 24, and 36 hours postoperatively. Blood samples were drawn simultaneously in the AVM group to measure levels of norepinephrine, epinephrine, renin, aldosterone, vasopressin, angiotensin I, and angiotensin II and correlated with significant hemodynamic changes. HR and CI increased significantly among patients with AVMs compared with patients with ICAs (p<0.001 and p=0.05, respectively). HR was significantly correlated with renin (r=0.60), norepinephrine (r=1.00), and vasopressin (r=0.66). CI was significantly correlated with epinephrine (r=1.00), renin (r=0.77), angiotensin II (r=0.71), and vasopressin (r=0.82). Patients with AVMs had a hyperdynamic state characterized by increases in HR and CI. These increases were accompanied by increased renin, norepinephrine, vasopressin, epinephrine, and angiotensin II serum concentrates. There were no significant differences in blood pressure changes between patients who had resection for AVM and those who had clipping of ICA, probably due to the use of sodium nitroprusside in the AVM group. Patients with AVMs had a hyperdynamic state with increases in epinephrine, norepinephrine, angiotensin II, plasma renin activity, and vasopressin. Whether this hyperdynamic state is caused by the resection of the AVM or the use of sodium nitroprusside (SNP) cannot be concluded. Blockage of these mediators preoperatively may help control blood pressure without sodium nitroprusside.