Liver blood flow during cardiac surgery.

OBJECTIVE: Impairment of liver blood flow and, therefore, potentially liver function, has important short-term consequences because of the liver's key metabolic importance and role in drug metabolism. The objective of this study was to quantify the effect of cardiac surgery on liver blood flow from before the induction of anaesthesia to 24 hours postoperatively. METHOD: Ten patients with no history of liver impairment, moderate or good left ventricular function, and undergoing routine hypothermic coronary artery bypass graft surgery, were entered into the study. Liver blood flow was determined by the clearance of indocyanine green (ICG), expressed as a percentage disappearance rate (PDR). RESULTS: The mean baseline percentage disappearence rate (PDR) of indocyanine green (ICG) was 19.84 +/- 4.47%/min. This increased marginally to 20.42 +/- 6.67%/min following the induction of anaesthesia, but after 15 min of cardiopulmonary bypass, the PDR fell to 13.51 +/- 3.69%/min; this was significantly lower than all other PDRs measured throughout the study. Prior to extubation, the PDR increased again to 20.01 +/- 3.72%/ min, and this level was maintained at 12 hours (PDR 20.32 +/- 3.53%min) and 24 hours (PDR 20.51 +/- 2.27%/min). CONCLUSION: The induction of anaesthesia and positive pressure ventilation do not affect liver blood flow. Cardiopulmonary bypass at 30 degrees C is associated with a significant reduction in liver blood flow, which returns to normal within 4-6 hours of surgery and remains normal for up to 24 hours after surgery.

Limitations of additive EuroSCORE for measuring risk stratified mortality in combined coronary and valve surgery.

OBJECTIVE: To study the use of the additive and logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) to predict mortality following adult combined coronary artery bypass grafting (CABG) and valve surgery. METHODS: Data were collected prospectively, from all four centres providing adult cardiac surgery in the north west of England, on 1769 consecutive patients undergoing combined CABG and valve surgery between April 1997 and March 2002. Observed in-hospital mortality was compared to predicted mortality as determined by both additive and logistic EuroSCORE. RESULTS: Observed mortality for simultaneous CABG and valve surgery was 8.7%, compared to 6.7% (additive) and 9.4% (logistic). Sixty-five percent of patients were classified as high-risk (additive EuroSCORE >5); the observed mortality was 11.5%, compared to 8.1% (additive) and 12.8% (logistic). Discrimination was similar in both systems as measured by the C statistic (additive 0.73, logistic 0.73). CONCLUSIONS: The logistic EuroSCORE is more accurate at predicting mortality in simultaneous CABG and valve surgery, as the additive EuroSCORE significantly under-predicts in this high-risk group.

Total Coronary Artery Revascularization Through a Mini-Sternotomy.

Revascularization of all significantly stenosed vessels remains the goal of coronary artery bypass surgery. Recent improvements in endoscopic instruments have resulted in the evolution of selective left anterior descending artery bypass grafting through a limited anterior small thoracotomy (LAST) incision. A major limitation of this technique is the inaccessibility for complete surgical revascularization in multivessel disease. In this article, we describe a minimally invasive technique for total coronary artery revascularization that combines conventional surgical techniques with the advantages of minimally invasive surgery. We have performed total coronary revascularization in 52 patients over a period of 16 months with consistently good results.