Validation of a new intraoperative technique to evaluate load-independent indices of right ventricular performance in patients undergoing cardiac operations.

BACKGROUND: Assessment of right ventricular performance in the perioperative period is difficult because there is no generally accepted method of measuring right ventricular volume. We set out to determine whether conductance technology could provide a valuable technique for the investigation of intraoperative right ventricular function. METHODS AND
RESULTS: Three validating studies were performed in 25 patients undergoing routine coronary revascularization. Study 1: The influence of conductance catheter position in the right ventricle was examined in 10 patients. Insertion of the conductance catheter through the outflow tract was associated with a larger gain constant and a smaller parallel conductance compared with insertion through the tricuspid valve. Study 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 any significant difference in right ventricular volume or contractile function. Study 3: Right ventricular performance before and after cardiopulmonary bypass was compared in 8 additional patients. There was a fall 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 technique can be used to study perioperative changes in right ventricular performance. Insertion of the conductance catheter through the outflow tract provides stable and reproducible data. There is significant impairment of right ventricular contractility in the early postoperative period.