Predictors of operative mortality following primary coronary artery bypass surgery.

BACKGROUND: Although quality assessment of coronary artery patients can be done by 30 days risk-adjusted operative mortality, it is still insufficient to study the outcome after primary coronary artery bypass graft surgery (CABG). In our study, we attempted to determine the factors, which can help predict operative mortality before and after CABG. METHODS: The study population consisted of 1000 prospective patients who underwent primary isolated CABG. Assessment was done by dividing the patients into two groups, i.e. non-survivors ( n= 12) and survivors ( n= 988). Data were analyzed using both univariate and multivariate models. RESULTS: On univariate analysis, recent acute myocardial infarction, intra-aortic balloon counterpulsation (IABC), left ventricular ejection fraction (LVEF) <25%, ventilator-associated pneumonia (VAP), tracheostomy, re-exploration, ventricular arrhythmias, low cardiac output (CO), multiple blood transfusions, post-operative renal dysfunction and longer intensive care unit and hospital stay were found as risk factors for mortality. Multivariate analysis showed that LVEF <25%,VAP, ventricular arrhythmias and low CO independently predicted mortality. Prior knowledge of these risk factors can help not only in predicting the outcome and the risks but also helps to plan the surgical and post-operative course of the patients to improve the morbidity and mortality. CONCLUSION: Our data suggest that operative mortality can be predicted prior to and after surgery considering factors such as LVEF, use of IABC, onset of ventricular arrhythmias and low CO.

Comparative study of pulsatile and nonpulsatile flow during cardio-pulmonary bypass.

The use of nonpulsatile flow during extracorporeal circulation remains popular despite theoretical advantages of pulsatile cardiopulmonary bypass (CPB). Pulsatile CPB is considered to be more physiological than nonpulsatile flow as the pulsatile energy ensures the patency of the vascular bed and mechanical motion of tissue fluid around the cell membrane, improves microcirculation and enhances diffusion. The purpose of this study was to compare the effect of pulsatile and nonpulsatile flow on the coagulation profile, liver and kidney function and also on the haemodynamics in patients undergoing coronary artery bypass grafting on CPB. One hundred patients between 35 and 65 years of age with normal left ventricular function were randomly divided into two equal groups: Pulsatile (P) and nonpulsatile (NP). Haematological parameters, clotting profile, renal parameters, hepatic function tests and haemodynamic variables were measured preoperatively and postoperatively at specific intervals. Surgical, anaesthetic and CPB regimen was standard in all cases. There was a decrease in platelet count during and after CPB in both groups. Coagulation profile and renal function parameters remained similar in both groups except that creatinine clearance was better in group P on the first postoperative day. Urine output was also better in group P. There was no change in liver function tests in both groups. The haemodynamic variables were comparable in both groups. The systemic vascular resistance was higher in group NP postoperatively and oxygen consumption was higher in group P post CPB. In conclusion we did not find any significant difference between pulsatile and nonpulsatile flow during CPB except the creatinine clearance and urine output were better in pulsatile group.

Beating heart versus conventional reoperative coronary artery bypass surgery.

BACKGROUND: The incidence of reoperative coronary artery bypass grafting is increasing with an increase in the number of patients undergoing coronary artery bypass surgery. The clinical outcome of redo coronary artery bypass grafting without cardiopulmonary bypass and conventional coronary artery bypass grafting using cardiopulmonary bypass are different. METHODS AND RESULTS: We compared clinical parameters in patients who underwent off-pump (n=156) versus on-pump (n=194) redo coronary artery bypass grafting performed between January 1995 and December 2001 in our institute, to determine if off-pump surgery has improved the surgical outcome of redo coronary artery bypass grafting and emerged as an ideal technique. Patients who underwent on-pump redo surgery required more postoperative blood transfusion (86.53% on-pump v. 12.82% off-pump. p=0.001), prolonged ventilatory support (>24 hours) (16.49% on-pump v. 7.7% off-pump, p=0.021) and higher inotropic support (23.71% on-pump v. 10.89% off-pump, p=0.003). On-pump redo coronary artery bypass grafting was also associated with a prolonged stay in the intensive care unit (40+/-6.2 hours on-pump v. 20+/-4.1 hours off-pump, p=0.001) and longer hospital stay (9+/-4.2 days on-pump v. 5+/-3.4 days off-pump, p=0.001). In-hospital mortality was higher in on-pump patients than in off-pump ones (7.7% v. 3.2%); however, this was not statistically significant (p=0.114). CONCLUSIONS: Off-pump redo coronary artery bypass grafting is a safe method of myocardial revascularization with lower operative morbidity and mortality, less requirement of blood products and early hospital discharge, compared with conventional on-pump redo coronary artery bypass grafting.