Facing the era of minimally invasive coronary grafting: current results of conventional bypass grafting for single-vessel disease.

BACKGROUND: The concepts of minimally invasive coronary artery bypass grafting have gained increasing attention and interest from cardiac surgeons. Operations through small incisions are mostly applied to patients with less extensive coronary disease, mostly single-vessel disease. The aim of this study was to identify a baseline level of conventional coronary bypass grafting for this group of patients, particularly with regard to surgical complications and immediate results. METHODS: Of 3,637 consecutive patients undergoing coronary artery bypass grafting during the period 1989 to 1995, 99 patients (2.7%) were identified to have single-vessel disease. The preoperative and hospital data of this subset of patients were analyzed. RESULTS: The left internal mammary artery was grafted in 96% of the patients, either as single graft to the left anterior descending artery or sequentially to the left anterior descending artery and a diagonal branch. Additional vein grafts were placed in 36 patients, and the mean number of distal anastomoses was 1.6 +/- 0.6. Mean ischemic time and cardiopulmonary bypass time were 15.3 +/- 9.6 minutes and 29.0 +/- 12.5 minutes, respectively. The patients were weaned from the ventilator 1.5 +/- 0.8 hours postoperatively, and all patients were out of bed the morning after the operation. No patients required homologous blood or plasma transfusions. The morbidity rate was low, and all patients survived. CONCLUSIONS: For this highly selected group of patients, coronary artery bypass grafting based on median sternotomy, cardiopulmonary bypass, and cardioplegic arrest carries a very high rate of immediate success. Such data may be useful as a baseline when considering the costs and benefits of new surgical procedures.

Heparinized cardiopulmonary bypass and full heparin dose marginally improve clinical performance.

BACKGROUND: The use of completely heparin coated cardiopulmonary bypass circuits in combination with a reduced systemic heparin dose has previously been shown to reduce postoperative bleeding after cardiac operations. However, it has remained unknown whether this effect was related to the improved biocompatibility of the heparin-treated surfaces per se or to the reduced exposure to circulating heparin. Therefore we investigated patients undergoing heparin-coated extracorporeal circulation and full systemic heparinization. METHODS: Two hundred seventeen patients having first-time myocardial revascularization were prospectively randomized either to a group in which a completely ("tip-to-tip") heparin-coated circuit (Duraflo II) was used for perfusion (n = 107) or to a control group (n = 110) in which an uncoated, but otherwise identical, circuit was used. Full systemic heparinization was induced in both groups (activated clotting time, > 480 seconds). The postoperative blood loss, requirements for homologous blood transfusions, clinical performance, and complications were recorded. RESULTS: The amount of postoperative mediastinal drainage was nearly identical in the two groups. The mean 18-hour drainage was 694 +/- 313 mL in the heparin-coated group and 679 +/- 269 mL in the control group (p = not significant). Three patients in the heparin-coated group and 6 patients in the control group received homologous red blood cell transfusions (p = not significant). The incidence of postoperative atrial fibrillation was significantly lower in the heparin-coated group (21.8%) than in the control group (43.1%) (p = 0.002). Otherwise, there were no significant differences in the extubation times, the incidence of perioperative myocardial infarction, the creatinine concentration, the incidence of neurologic dysfunction, the progress in physical rehabilitation, or the hemoglobin concentration at discharge. CONCLUSIONS: The use of completely heparin coated cardiopulmonary bypass circuits and full systemic heparinization in patients undergoing coronary artery bypass procedures did not reduce postoperative bleeding or change clinical performance, except for a significant decrease in the incidence of postoperative atrial fibrillation.

Complete heparin-coated cardiopulmonary bypass and low heparin dose reduce complement and granulocyte activation.

Complete heparin-coated extracorporeal circuits, including cardiotomy reservoir, have recently become available for routine cardiac surgery. The effects on complement and granulocyte activation using a heparin-coated circuit in combination with reduced systemic heparinization (activated clotting time (ACT) > 250 s) were studied in 33 patients undergoing elective first time myocardial revascularization. The patients were prospectively randomized either to a heparin-coated group (Group H, n = 17), or to a control group (Group C, n = 16) treated with an identical uncoated circuit and full heparin dose (ACT > 480 s). During cardiopulmonary bypass (CPB) the C3 activation products C3b, iC3b, and C3c (C3bc) and the terminal SC5b-9 complement complex (TCC) increased markedly in both groups compared to baseline, but to a much lesser extent in the heparin-coated group. The maximal increase of C3bc during the operation was a median of 28 arbitrary units (AU)/ml in the heparin-coated group, compared to 45 AU/ml in the control group (P = 0.01). Similarly, in Group H the maximal increase of TCC was significantly lower (median 0.8 AU/ml) than the levels recognized in Group C (median 1.9 AU/ml) (P < 0.0001). The release of the granulocyte activation enzymes lactoferrin and myeloperoxidase also increased during CPB in both groups compared to baseline level. The maximal increase of lactoferrin concentration was a median of 229 micrograms/l in Group H and significantly lower than 647 micrograms/l in the control group (P = 0.0002). As for myeloperoxidase, there were no significant intergroup differences. In conclusion, a complete heparin-coated circuit and low systemic heparinization for CPB in coronary artery surgery were associated with reduced activation of the complement system and less release of lactoferrin. The results indicate improved biocompatibility of this option for extracorporeal circulation.

Complete heparin-coated (CBAS) cardiopulmonary bypass and reduced systemic heparin dose; effects on coagulation and fibrinolysis.

OBJECTIVE: Heparin-coated extracorporeal circuits allow reduced amounts of systemic heparin and protamine. However, the effects on the coagulation and fibrinolytic systems when reducing systemic anticoagulation, have partly remained unknown. METHODS: Thirty-three patients undergoing elective first time myocardial revascularization were prospectively randomized either to have a cardiopulmonary bypass (CPB) circuit completely coated with covalently bound heparin, in combination with reduced systemic heparinization (activated clotting time (ACT) > 250 s (n = 17), or to a control group perfused with identical but uncoated circuits and full heparin dose (ACT > 480 s) (n = 16). Tests indicative of thrombin generation, platelet activation, and fibrinolytic activity were performed intraoperatively and postoperatively. RESULTS: During CPB, the plasma level of prothrombin fragment 1.2 (PF 1.2) increased from median 1.5 (1.1-1.9) nmol/l to 5.4 (3.3-6.6) nmol/l in the heparin-coated group, and was significantly higher (P = 0.01) than the increase from 1.4 (1.2-1.9) nmol/l to 3.2 (2.2-4.3) nmol/l seen in the control group. However, the increase on CPB was modest compared to the major elevation observed after completed surgery and reversal of the anticoagulation. The concentrations reached median 9.7 (6.8-19.5) nmol/l in the heparin-coated group and 13.2 (4.2-18.4) nmol/l in the control group (no significant intergroup difference). A similar pattern was observed for the thrombin-antithrombin (TAT) complex. Regression analysis revealed significant correlation between the levels of the thrombin markers and duration of CPB in both groups (P < 0.05). There was no correlation between ACT or plasma heparin levels on bypass and the PF 1.2 and TAT complex. The platelet release of beta-thromboglobulin increased in both groups during CPB and significantly more in the control group at the end of bypass (P < 0.01), indicating less platelet activation in the heparin-coated group. There were no significant intergroup differences with regard to fibrinolytic activity. Plasma fibrinogen as well as platelet counts were unchanged after the operation, compared to baseline. Except for one patient in the control group sustaining perioperative myocardial infarction, the postoperative course was uneventful in all cases. CONCLUSIONS: Completely heparin-coated CPB can safely be performed in combination with reduced systemic heparinization. The heparin and protamine amounts could be lowered to 35% of normal doses. Indications of more thrombin generation on CPB compared to the uncoated controls were seen, but the levels remained within low ranges in both groups. There was no evidence of thromboembolic episodes or clot formation in the extracorporeal circuits.

Effects on coagulation and fibrinolysis with reduced versus full systemic heparinization and heparin-coated cardiopulmonary bypass.

BACKGROUND: Extracorporeal circulation with circuits coated with surface-bound heparin has allowed reduced levels of systemic heparinization. Clinical benefits have included reduced postoperative bleeding and less homologous blood usage. However, the effects on the hemostatic and fibrinolytic systems have remained in part unknown. METHODS AND RESULTS: Indications of thrombin generation, platelet activation, and fibrinolytic activity were investigated in patients undergoing coronary artery bypass surgery. Two groups were perfused with cardiopulmonary bypass (CPB) circuits completely coated with surface-bound heparin: one group with low systemic heparin dose (activated clotting time [ACT] > 250 seconds; n = 17) and a second group having a full heparin dose (ACT > 480 seconds; n = 18). A third control group was perfused with ordinary uncoated circuits and full heparin dose (n = 17). The plasma level of thrombin-antithrombin complex and prothrombin fragment 1.2 increased in all groups during bypass, and somewhat more in both the heparin-coated groups toward the end of CPB, compared with the control group (P < .01). However, the increase during CPB was minimal compared with the major elevation observed 2 hours after surgery in all groups. Platelet release of beta-thromboglobulin increased in all groups (P < .01) during CPB and significantly more in the high-dose group compared with the other two groups (P = .03). Fibrinolytic activities were similar in all groups, and there were no indications of major consumption of coagulation factors. CONCLUSIONS: Reduced systemic heparinization (ACT > 250 seconds) in patients having extracorporeal circulation with completely heparin-coated circuits did not lead to increased thrombogenicity. Thrombin formation remained within low ranges during CPB compared with patients receiving a full heparin dose and with the major elevations observed after surgery.

Consistent non-pharmacologic blood conservation in primary and reoperative coronary artery bypass grafting.

Because much interest has been focused on blood conservation using different drugs and complicated blood cell processing devices, we analyzed our results with the use of a non-pharmacologic, simple and inexpensive program for blood salvage in 2326 patients undergoing myocardial revascularization. The material was divided into two groups: patients undergoing a primary coronary bypass operation (Group P, n = 2298) and a smaller subset of patients undergoing repeat coronary bypass operation (Group R, n = 28). At least one internal mammary artery was grafted in 99% of the patients, with supplemental saphenous vein grafts. Intraoperatively, autologous heparinized blood was removed before bypass and retransfused at the conclusion of extracorporeal circulation. The volume remaining in the extracorporeal circuit was returned without cell processing or hemofiltration. Autotransfusion of the shed mediastinal blood was continued hourly up to 18 h after surgery in all patients. The mean postoperative mediastinal drainage in group R was 543 +/- 218 ml, compared to 703 +/- 340 ml in Group P (P = 0.01). In Group R, 1 patient (3.6%) received packed red cells and no patients were given other homologous blood products, compared to 33 patients (1.4%) given red cells and 35 patients (1.5%) given plasma transfusion in Group P (NS). Thus, in total, 2257 patients (97.0%) were not exposed to any homologous blood products during hospitalization. Total hemoglobin loss was significantly higher in Group R, resulting in a mean hemoglobin concentration at discharge of 109 +/- 13 g/l, compared to 121 +/- 14 g/l in Group P (P = 0.0002).(ABSTRACT TRUNCATED AT 250 WORDS)

Tranexamic acid (Cyklokapron) is not necessary to reduce blood loss after coronary artery bypass operations.

The contribution of fibrinolysis to postoperative bleeding after cardiopulmonary bypass led to routine use of tranexamic acid, a potent antifibrinolytic drug, for a period of time. Two hundred patients undergoing elective coronary artery bypass operations were studied, one group of 100 patients given tranexamic acid (40 mg/kg) (group I) after bypass and one subsequent group of 100 patients (group II) serving as a control group. All patients were treated by the same team, and the groups were comparable in all major clinical parameters. The mean mediastinal drainage in group I was 565 +/- 239 ml versus 656 +/- 257 ml in group II. Univariate and multivariate analysis revealed statistical significance (p = 0.02) when corrected for body surface area. However, applying a consistent blood conservation protocol, including removal of autologous blood before bypass for retransfusion after bypass, returning of all oxygenator and tubing contents to the patients, and autotransfusion of the mediastinal shed blood up to 18 hours postoperatively, resulted in nearly identical hemoglobin concentration at discharge (119 +/- 14 gm/L in group I and 121 +/- 14 gm/L in group II). The prevalence of postoperative myocardial infarction included five patients in group I compared with one patient in group II. Although not statistically significant (p = 0.2), the difference is of concern. Tranexamic acid has a beneficial effect on reducing postoperative bleeding after coronary artery bypass operations. The routine use of the drug is not recommended, however, because its effect is a weak one, and it may be of potential hazard by precipitating thrombosis and eventual myocardial infarction.

Coronary artery bypass surgery with minimal use of homologous blood. Effects of a simple and inexpensive blood conservation programme.

Restriction of donor blood transfusions in cardiac surgery should decrease the risk of infective contamination and antigenicity. Following a simple, systematic and inexpensive blood conservation program, we report on 250 consecutive patients undergoing elective coronary artery bypass surgery, 247 (98.6%) of whom did not need homologous blood transfusions. At least one internal mammary artery was grafted in all but one patient, in combination with saphenous vein grafts. Intraoperatively, autologous heparinized blood was removed before bypass and retransfused at the conclusion of extracorporeal circulation. The remaining volume of the oxygenator and tubing set was retransfused without any cell processing or hemofiltration. Using the hard-shell cardiotomy reservoir from the heart lung machine, autotransfusion of the shed mediastinal blood was continued hourly up to 18 h after surgery. The mean postoperative mediastinal bleeding was 622 +/- 287 ml, of which 589 +/- 296 ml was autotransfused. Five patients (2.0%) needed re-exploration for bleeding, and three of these received 1-4 units of homologous blood. No other patients needed red cell transfusions. Seven patients were given a mean of 2.6 units of fresh frozen plasma because of coagulopathy. Thus, altogether 240 patients (96%) were not exposed to any homologous blood products during their hospital stay. Morbidity was low. At discharge, the mean hemoglobin concentration was 12.0 +/- 1.4 g/dl and the mean hematocrit 36.0 +/- 4.2%. There were no deaths.

Cerebral carbon dioxide reactivity during nonpulsatile cardiopulmonary bypass.

Five patients undergoing extensive cerebral monitoring during cardiopulmonary bypass (CPB) procedures were subjected to studies on cerebral CO2 reactivity during nonpulsatile CPB. The cerebral monitoring included recording of arterial blood pressure (BP), central venous pressure (CVP), epidural intracranial pressure (EDP), cerebral electrical activity by a cerebral function monitor (CFM), and middle cerebral artery (MCA) flow velocity by transcranial Doppler technique. The cerebral perfusion pressure (CPP) was thus continuously recorded (CPP = BP - EDP). During steady-state CPB with constant hematocrit, temperature, and arterial carbon dioxide tension (PaCO2), MCA flow velocity varied with changing CPP in a pressure-passive manner, indicating that the cerebral autoregulation was not operative. During moderately hypothermic (28 to 32 degrees C), nonpulsatile CPB, with steady-state hematocrit, temperature, and pump flow, we deliberately and rapidly changed PaCO2 for periods of 1 or 2 minutes by increasing gas flow to the membrane oxygenator, thereby testing the cerebral CO2 reactivity. Nineteen CO2 reactivity tests, performed at CPP levels ranging from 17 to 75 mm Hg, disclosed that the cerebral CO2 reactivity decreased with CPP, especially with CPP levels below 35 mm Hg. In these patients, concomitant changes in CPP during the CO2 reactivity test could be compensated for by adjusting the observed change in MCA flow velocity. The corrected CO2 reactivity values obtained in this way ranged from below 1.0 (observed at CPP levels below 20 mm Hg) to a 3.0 to 4.5% X mm Hg-1 change in PaCO2 (observed at CPP levels above 35 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)