Low-risk Coronary Artery Bypass Grafting Research Articles

Basal and nitroglycerin-induced exhaled nitric oxide before and after cardiac surgery with cardiopulmonary bypass

Exhaled nitric oxide (NO) may reflect NO production and consumption but the pulmonary origin of NO in exhaled gas is not clear. There are also conflicting data on exhaled NO after cardiopulmonary bypass (CPB). Because intravenous nitrovasodilators increase exhaled NO by conversion to NO in the lung, we measured basal and nitroglycerin (GTN)-induced exhaled NO in patients having low-risk coronary artery bypass graft (CABG) operations using routine CPB. We reasoned that GTN-induced exhaled NO would be a primarily vascular mechanism, which would contrast with the airway epithelial origin of basal exhaled NO, and that they might be differentially influenced by CPB. Breath-to-breath concentrations of gas phase NO were measured in 12 CABG patients before and 1, 3 and 6 h after CPB. After the baseline measurements, three increasing doses of 1, 2 and 3 micro g kg(-1) intravenous GTN were given by a central venous catheter and exhaled NO and haemodynamic responses were recorded. Intravenous administration of 1, 2 and 3 micro g kg(-1) doses of GTN produced a dose-dependent increase in exhaled NO and a reduction in systemic blood pressure. Baseline exhaled NO remained unchanged. Exhaled NO but not blood pressure responses were reduced 1 and 3 h after CPB. The capacity of the lungs to increase exhaled NO in response to intravenous GTN is reduced after CPB, suggesting microvascular injury and/or atelectasis after routine open-heart surgery.

Economic impact of preoperative intraaortic balloon pump therapy in high-risk coronary patients

Background. The efficacy of preoperative intraaortic balloon pump therapy in high-risk coronary patients has been demonstrated earlier. Methods. This study investigates the economic aspect by a detailed cost analysis of pooled information from two previously published randomized studies and 144 consecutive low-risk coronary artery bypass graft operations. Costs for patients receiving preoperative intraaortic balloon pump therapy before aortic cross-clamping (n = 62) were compared to those in a control group (n = 50). Detailed cost analysis was based on data provided by the hospital finance department. Results. The total hospital costs were as follows: low-risk coronary artery bypass graft operations cost 35,335 ± 1,694 Swiss francs ($23,400 ± $1,121); high-risk coronary artery bypass graft without preoperative intraaortic balloon pump therapy cost 65,892 ± 31,719 Swiss francs ($43,637 ± $21,006); and high risk coronary artery bypass graft with preoperative intraaortic balloon pump therapy cost 41,948 ± 10,379 Swiss francs ($27,780 ± $6,874) ( p = 0.0015). There were no significant differences in average cost among the preoperative intraaortic balloon pump therapy subgroups. Conclusions. Preoperative intraaortic balloon pump therapy in high risk coronary patients is significantly cost-beneficial, With an average saving of 24,000 Swiss francs ($16,000) on the total hospital cost, a 36% cost reduction.

Peri-operative myocardial tissue injury and the release of inflammatory mediators in coronary artery bypass graft patients.

This study was conducted to evaluate to what extent the ischemia-reperfusion injury resulting from the cardiopulmonary bypass (CPB) and aortic cross-clamping procedures during coronary artery bypass grafting (CABG) contributes to the systemic inflammatory response generally found in these patients. Serum levels of enzymes (CK and CK-MB) and non-enzymatic proteins (FABP and myoglobin) as markers of myocardial tissue injury, bactericidal permeability increasing protein (BPI) as an indicator of neutrophil activation, interleukin-6 (IL-6) as inducer of the acute phase response and lipopolysaccharide binding protein (LBP) as parameter of the acute phase response were measured in 15 low-risk CABG patients with cardiopulmonary bypass (CPB), and 17 low-risk CABG patients without CPB. Already 0.5 h after reperfusion significantly increased plasma levels of all markers of myocardial tissue injury were noted in patients having surgery with CPB, but not in non-CPB patients. No significant differences were found between both groups for BPI and IL-6 levels in the early reperfusion period. BPI and IL-6 levels were higher in the non-CPB group on the first post-operative day (P < 0.05). However, no correlations were found for any marker of peri-operative tissue damage with either early neutrophil activation, or acute phase reactants. Perioperative myocardial injury resulting from CPB and aortic cross-clamping in low-risk CABG patients does not contribute to the release of inflammatory mediators in these patients.

Heparinbeschichtung des extrakorporalen Kreislaufs: Gerinnungsaktivierung, Verbrauch und Fibrinolyse in einer randomisierten Studie an Koronarbypasspatienten

Hemorrhage after cardiopulmonary bypass (CPB) is associated with increased fibrinolytic and clotting activity. As pathogenic factors artificial (nonbiologic) surface contact and damage of corpuscular blood components are discussed. The aim of this study was to evaluate the impact of heparin-coated circuits on coagulation and fibrinolytic parameters, platelet count and postoperative blood loss in low-risk cardiac patients.¶ Fifty-two patients undergoing coronary artery bypass grafting (CABG) were randomly assigned to totally heparin coated (BiolineTM, Jostra, Hirrlingen, Germany) or identical uncoated extracorporeal circuits in a double blind protocol. Initial heparin dosage was equal for coated and uncoated circuits. Systemic anticoagulation was maintained with heparin in both groups.¶ Coagulation and fibrinolytic parameters showed a parallel perioperative course. Postoperative platelet count was significantly higher with heparin coating (152000/μl±46000 vs. 125000/μl±44000, p=0.029). Blood loss was lower with heparin coating but did not reach statistical significance. Heparin consumption was not reduced in heparin-coated circuits.¶ Heparin coating of cardiopulmonary bypass circuits does not improve hemostatic disorders in low risk CABG patients. Higher postoperative platelet counts suggest clinical benefit for high-risk patients with extended duration of bypass. Our data do not support reducing systemic heparin doses with heparin-coated circuits.

Central venous catheter use in low-risk coronary artery bypass grafting

Background. To assess the impact of central venous pressure catheter monitoring in low-risk coronary artery bypass grafting (CABG), we compared the hospital course of patients undergoing CABG with central venous pressure catheter monitoring with that of similar patients undergoing CABG with pulmonary artery catheter monitoring. Methods. All isolated primary CABG procedures (n = 312) performed between April 22 and October 31, 1996, were evaluated, and 194 patients meeting six central venous pressure catheter use criteria were identified. Of these 194 patients, 133 (68%) underwent CABG with central venous pressure catheter monitoring, and 61 (32%) had pulmonary artery catheter monitoring owing to surgeon or anesthesiologist preference. Results. In-hospital mortality was similar. A trend toward increased overall complications was seen in the pulmonary artery catheter group. The total volume infused in the first 12 hours, the 24-hour weight gain, and the intubation time were significantly greater in the pulmonary artery catheter group. Increases in intensive care unit length of stay and in total hospital charges trended toward statistical significance in the pulmonary artery catheter group. Conclusions. Pulmonary artery catheter use in low-risk patients undergoing CABG was associated with greater weight gain and longer intubation time and may be associated with increased morbidity and utilization of hospital resources.

Centrifugal pump and heparin coating improves cardiopulmonary bypass biocompatibility

Centrifugal pumps are being used increasingly for short-term extracorporeal circulation purposes such as during heart operations. Whether the centrifugal pump improves the cardiopulmonary bypass biocompatibility has not been fully documented. A roller pump (n = 20) was compared in vivo with a centrifugal pump (n = 20) in groups of patients in which cardiopulmonary bypass circuits that were either totally heparin coated (Carmeda BioActive Surface; n = 20) or uncoated (n = 20) were used. We expected the heparin coating to attenuate blood activation, thus possibly making the comparison of the two pumps easier with respect to their different blood activation potentials. Samples of blood plasma, obtained during cardiopulmonary bypass from low-risk coronary artery bypass grafting patients, were analyzed for hemolysis (plasma haemoglobin), complement activation (C3bc and the terminal complement complex), a complement lytic inhibitor (vitronectin), coagulation activation (fibrinopeptide A), granulocyte activation (lactoferrin), and platelet activation (beta-thromboglobulin). The concentrations of terminal complement complex, lactoferrin, and beta-thromboglobulin were significantly lower in association with heparin-coated surfaces. The concentration of plasma hemoglobin was significantly lower in association with the centrifugal pump. In uncoated circuits, the beta-thromboglobulin level was significantly higher in association with the roller pump than with the centrifugal pump, but this significant reduction in the beta-thromboglobulin level did not hold true for the heparin-coated circuit group. A heparin-coated cardiopulmonary bypass surface reduces the blood activation potential during cardiopulmonary bypass, and the centrifugal pump causes less hemolysis than the roller pump.

Arterial and venous cytokine response to cardiopulmonary bypass for low risk CABG and relation to hemodynamics

During and after cardiopulmonary bypass (CPB), cytokines may affect cardiac performance and the immune response and are therefore of diagnostic and therapeutic interest. We have used EIA/EASIA kits to measure arterial and venous levels of interleukin-1-beta (IL-1-beta), IL-2, IL-2 receptor (IL-2-R), IL-6, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma in 12 men and 3 women (mean age 59.4 +/- 8.5 years, mean left ventricular ejection fraction 66 +/- 11%, average of 2.5 +/- 0.64 vessels affected by disease) undergoing elective coronary artery bypass grafting (CABG). On average each patient received 3 +/- 0.85 bypass grafts and required a postoperative maximum dopamine-dose of 3.8 micrograms/kg per min. Mean CPB and operation times were 60 +/- 21 min, and 132 +/- 16 min, respectively. During CPB, the venous levels of IL-2 temporarily decreased from 234 to 0 (p < 0.05) pg/ml and arterial and venous levels of IL-2-R temporarily decreased from 28 to 16, and 36 to 18 pM (p < 0.05), respectively. After termination of CPB, there was an increase in the arterial and venous levels of IL-6 from below 3 to 253 and 277 pg/ml (p < 0.05) and TNF-alpha from 1.1 to 5.7 and 0.7 to 4.0 pg/ml, respectively (p < 0.05). Tumor necrosis factor-alpha-increases peaked 30 min, and IL-6 increases peaked 4 h after termination of CPB. Twenty-four hours after the end of CPB, IL-6 showed a tendency to return to baseline, but still remained significantly elevated.(ABSTRACT TRUNCATED AT 250 WORDS)