Effect of Preoperative Renin-Angiotensin System Antagonists on the Difference between Radial and Femoral Arterial Pressure after Cardiopulmonary Bypass in Patients Undergoing Valvular Heart Surgery

Background: Femoral to radial arterial pressure gradient (∆P) often develops after cardiopulmonary bypass (CPB) where radial artery pressure (RAP) does not reflect the actual perfusion pressure. Renin-angiotensin system antagonists (RAS-A) are increasingly prescribed preoperatively which causes vasodilation and vascular remodeling. We evaluated the effect of RAS-A medication on ∆P after CPB in patients undergoing valvular heart surgery. Methods: Eighty-five patients scheduled for elective valvular heart surgery for regurgitant lesions were divided into two groups: the RAS-A group, in which patients were on RAS-A preoperatively (n = 52) and the control group (n = 33). Hemodynamic variables including RAP, femoral arterial pressure (FAP), body temperature, and hematocrit were recorded at after induction of anesthesia, pre-and post-CPB and sternum closure. Results: After CPB, systolic ∆P was significantly greater in the RAS-A group than in the control group. Nine (27%) and 36 (69%) patients after CPB, and 6 (18%) and 23 (44%) patients after sternum closure developed systolic ∆P more than 10 mmHg, in the control and RAS-A group, respectively, which were statistically significant. Body temperature, hematocrit and systemic vascular resistance index were not different between groups. Conclusions: Preoperative treatment with RAS-A resulted in clinically significant ∆P after cardiopulmonary bypass in about 70% of patients undergoing valvular heart surgery. Concomitant monitoring of FAP with RAP might be helpful to prevent inadequate vasopressor therapy guided by inaccurate RAP after CPB in this subset of patients.