Oxidative stress during coronary artery bypass operations: importance of surgical trauma and drug treatment.

OBJECTIVE: To investigate oxidative stress and myocardial injury at different stages of coronary artery bypass grafting (CABG). DESIGN: Twenty patients underwent CABG with use of cardiopulmonary bypass (CPB) and with intermittent sampling of plasma and urine. Main markers were: 8-iso-PGF2alpha (oxidative stress); troponin T (myocardial injury); and 15-keto-dihydro-PGF2alpha and hsCRP (inflammation). RESULTS: Plasma 8-iso-PGF2alpha increased after start of surgery, but there was no further rise during CPB or after aortic cross-clamp release and no significant myocardial arterio-venous differences. An increase in troponin T was seen early after the operation, but no relationship was established between 8-iso-PGF2alpha and troponin T. 8-iso-PGF2alpha levels were elevated by preoperative withdrawal of acetylsalicylic acid (ASA) but reduced by intraoperative use of heparin. 15-keto-dihydro-PGF2alpha was elevated during operation and hsCRP following operation. CONCLUSIONS: In the present study oxidative stress was multifactorial in origin with main impacts from surgical trauma, less from CPB and little if any from myocardial ischemia-reperfusion events. In addition, cardiovascular drugs in common use like ASA and heparin seemed to influence the pro- and antioxidant balance, a finding that has to be confirmed in future studies.

Guiding surgical cannulation of the inferior vena cava with transesophageal echocardiography.

UNLABELLED: We studied 150 adult cardiac surgery patients to assess visualization of the venous cannula and the venous system by intraoperative transesophageal echocardiography and to register the incidence of cannulation of hepatic veins. The quality of images, the dimensions of the venous system, the position of the venous cannula, and the adequacy of venous return were registered. Acceptable image quality of the inferior vena cava and the right hepatic vein (RHV) was obtained in 95% and 87% of cases, respectively. Considerable individual variations were found in the dimensions of the venous system. The cannula position could be determined in 99% of the cases. Ten percent of venous cannulae were primarily placed in the RHV. A short distance between the eustachian valve and the RHV possibly predisposes to cannulation of the RHV. No other patient-related factors were associated with cannula position. Placement of the cannula deep in the inferior vena cava was associated with reduced venous return and may be a more important cause of reduced return than a cannula positioned in a hepatic vein. IMPLICATIONS: Correct positioning of the venous cannula draining blood to the cardiopulmonary bypass circuit is important. Intraoperative transesophageal echocardiography allows satisfactory determination of the cannula position in nearly all patients. Ten percent of venous cannulae are primarily positioned in the right hepatic vein and not in the inferior vena cava as intended.