ABSTRACT
Objective To investigate the effects of heart displacement on hemodynamics during off-pump coronary artery bypass grafting (OP-CABG) while the sites for anastomosis were being exposed. Methods Forty-seven patients of both sexes (36 male, 11 female) aged 50-82 years undergoing OP-CABG were enrolled in the study. Preoperative cardiac function was assessed : class Ⅱ in 22 patients; Ⅲ in 23 and Ⅳ in 2 according to NYHA classification.The mean ejection fraction was 0.55?0.14 before surgery.They received on average 3.2 grafts. Premedication consisted of intramuscular morphine 10 mg, midazolam 3-5 mg and scopolamine 0.3 mg.Before induction of anesthesia ECG and SpO2 were monitored and radial artery was cannulated for continuous direct BP monitoring. Anesthesia was induced with midazolam 0.1 nig?kg-1 , fentanyl 4?g?kg-1 and pancuronium 0.1 mg?g-1 iv.The patients were mechanically ventilated after tracheal intubation and PETCO2 was maintained at about 40 mm Hg. Anesthesia was maintained with isoflurane and 50%-60% N2O in O2 and intermittent intravenous boluses of fentanyl and pancuronium. Swan-Ganz catheter which can continuously monitor mixed venous blood O2 saturation (SvO2) was placed in pulmonary artery via right internal jugular vein. SvO2, cardiac output (CO), BP, pulmonary arterial pressure (PAP) and HR were continuously monitored. Right atrial pressure (RAP) and PAWP were measured intermittently. Cardiac index (CI),stroke index (SI),systemic vascular resistance index (SVRI),PVRI, left and right ventricular work index (LVWI,RVWI) and left and right ventricular stroke work index (LVSWI,RVSWI) were calculated. The hemodynamic parameters were recorded after induction of anesthesia before surgery (T1,baseline),before heart displacement (T2), while anastomosis to anterior descending branch was being made (T3), while anastonosis to right coronary artery or posterior descending branch (T4) and to left circumflex artery or diagonal branch (T5) was being made, after normal heart position was resumed (T6) and at the end of operation (T7). Results While anastomosis to the anterior descending branch was being made (T3) SI and LVSWI significantly decreased as compared with the baseline (P