Evaluation of Right Ventricular Function after Coronary Artery Bypass Grafting

Background- Decreased right ventricular function is a suggested echocardiographic finding after coronary artery bypass grafting (CABG). However, the assessment of RV function is still technically difficult because of the complicated geometry of the RV. The significance and time course of RV dysfunction and its relation to left ventricular ejection fraction and pump time have not been elucidated, however. Objectives- In this prospective study, we assessed RV function measured from echocardiographic tricuspid annular plane systolic excursion (TAPSE), myocardial systolic velocity and timing interval determined by Doppler tissue imaging (Sm), and myocardial performance index (tei index) obtained from cardiac time interval analysis. Methods- In 30 patients accepted for CABG, a baseline echocardiography was done before operation, followed by repeated echocardiograms one week and one month after CABG. RV function was assessed using the magnitude of TAPSE, peak Sm measured at lateral tricuspid annulus and myocardial performance index defined as the sum of isovolumic contraction and relaxation time divided by ejection time. Also the time interval from the Q point of the electrocardiogram to the beginning of the tricuspid annular Sm and Em waves of tissue Doppler imaging was measured before and after operation. Results- TAPSE and peak Sm velocity was significantly reduced one week after CABG (2.34 vs. 1.53 cm, 12.67 vs. 8.5 cm/s, p<0.001) and remained so after one month(1.65 cm, 8.9 cm/s). RV myocardial performance index (tei index) was significantly increased one week after CABG (0.35 vs. 0.78, p<0.001) and remained unchanged one month postoperatively (0.86). There was no significant difference in Q-S and Q-E intervals before and after CABG (89 vs. 92 ms, 433 vs. 411 ms). Conclusion- RV function is significantly reduced after CABG and remained so after one month. The severity of RV dysfunction seems to be correlated with LVEF, duration of CPB time and extent of CAD (more severe postoperative RV dysfunction in patients with 3VD compared to 1VD or 2VD). There is no correlation between postoperative RV dysfunction and the number of grafts performed and RCA lesions.