VALIDATION OF A NEW INTRAOPERATIVE TECHNIQUE TO EVALUATE LOAD-INDEPENDENT INDEXES OF RIGHT-VENTRICULAR PERFORMANCE IN PATIENTS UNDERGOING CARDIAC OPERATIONS

Background: Assessment of right ventricular performance in the periope rative period is difficult because there is no generally accepted meth od of measuring right ventricular volume. We set out to determine whet her conductance technology could provide a valuable technique for the investigation of intraoperative right ventricular function. Methods an d results: Three validating studies were performed in 25 patients unde rgoing routine coronary revascularization. Study 1: The influence of c onductance catheter position in the right ventricle was examined in 10 patients. Insertion of the conductance catheter through the outflow t ract was associated with a larger gain constant and a smaller parallel conductance compared with insertion through the tricuspid valve. Stud y 2: The reproducibility of contractility measurements with the use of a conductance catheter was examined in 7 additional patients. Removal and reinsertion of the conductance catheter was not associated with a ny significant difference in right ventricular volume or contractile f unction. Study 3: Right ventricular performance before and after cardi opulmonary bypass was compared in 8 additional patients. There,vas a f rill in the slope of the right ventricular preload recruitable stroke work from 15.6 (3.8) to 11.0 (5.1) mm Hg (P = .01) and an increase in the slope of the end-diastolic pressure-volume relations from 0.05 (0. 02) to 0.11 (0.05) mm Hg/mL (P = .001). Conclusions: The conductance t echnique can be used to study perioperative changes in right ventricul ar performance. Insertion of the conductance catheter through the outf low tract provides stable and reproducible data. There is significant impairment of right ventricular contractility in the early postoperati ve period.