Objectives: Data on intraoperative three-dimensional derived right ventricular free-wall strain (3D-RV FWS) is sparse. We sought to evaluate the normal range of intraoperative 3D-RV FWS in patients scheduled for coronary artery bypass graft (CABG) surgery and compare to conventional echocardiographic parameters. Design: Prospective observational study. Setting: Single university hospital. Participants: 150 patients with preserved left and right ventricular function and sinus rhythm, without significant heart valve disease or pulmonary hypertension undergoing isolated onpump CABG surgery, with an uneventful, complication-free intraoperative course. Interventions: 3D-RV FWS analysis and conventional echocardiographic assessment of right ventricular function were performed intraoperatively in anesthetized and ventilated patients using transesophageal echocardiography (TEE). All echocardiographic measurements were performed under stable hemodynamic conditions and predefined fluid management without any vasoactive support or pacing. Measurements and Main Results: We used TomTec 4D RV-Function 2.0 software for assessment of 3D-RV FWS and three-dimensional right ventricular ejection fraction (3D-RV EF). Philips QLAB 10.8 was used to evaluate tissue velocity of the tricuspid annulus (RV S´), tricuspid annular systolic excursion (TAPSE), and RV fractional area change (FAC). Assessment of 3D-RV FWS was feasible in 95% of patients. No included patient experienced a serious perioperative complication. In our group of patients, median values with interquartile range (IQR) for 3D-RV FWS and 3D-RV EF were - 25.2 (IQR -29.9 - -21.8) and 46.3% (IQR 41.0 - 50.1%), respectively. RV FAC, RV S´ and TAPSE accounted for 39.7% (IQR 34.5 - 44.4%), 14.8cm/s (IQR 11.8 - 19.0cm/s) and 22 mm (IQR 20-25mm). Normal range (2.5% to 97.5% percentile) for 3D-RV FWS was -37.1 to -12.8. There was no relevant correlation of 3D-RV FWS to postoperative outcome in this group of CABG patients. Conclusion: We present distribution values for intraoperative 3D-RV FWS and conventional parameters of RV function assessment in a healthy on-pump CABG patient population without serious perioperative complications. We observed no correlations of these parameters with any of the outcome parameters considered. Therefore, we consider these values to be intraoperative TEE-assessed normal values that can be expected in onpump CABG patients.
