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Ann Thorac Surg 2003;76:1144-1148
© 2003 The Society of Thoracic Surgeons
a Oslo Heart Center, Oslo, Norway
Accepted for publication April 1, 2003.
* Address reprint requests to Dr Øvrum, Oslo Heart Center, Box 2684, St. Hanshaugen, 0131 Oslo, Norway.
e-mail: eivind.ovrum{at}hjertesenteret.no
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Abstract |
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METHODS: The on-pump strategy includes routine use of heparin-coated circuits combined with low systemic heparinization (activated coagulation time of more than 250 seconds), intention of total revascularization within limited ischemic times and pump times, minimal use of blood transfusions, early extubation, and rapid postoperative recovery. The data from the first 2,500 consecutive first-time coronary artery bypass grafting patients (January 1998 to February 2002) treated with this protocol were retrospectively analyzed.
RESULTS: There were 487 female (median age 68 years) and 2013 male (median age 64 years) patients. A median of four (one to nine) (mean 4.5 ± 1.2) distal anastomoses were created, and the median aortic cross-clamp time and pump time were 34 and 54 minutes, respectively. At least one internal mammary artery was used in 99.7% of the patients. Blood or bank blood products were given to 118 patients (4.7%). Median extubation time was 1.5 hours. The stroke rate was 0.8%, transient neurologic deficits occurred in 0.6% of the patients, and the incidence of perioperative myocardial infarction was 1.1%. By the fifth day, 91% of the patients were ready for discharge. Seven patients (0.28%) died during their hospital stay.
CONCLUSIONS: Coronary artery bypass grafting with heparin-coated cardiopulmonary bypass circuits and reduced systemic anticoagulation resulted in excellent clinical results, with minimal blood transfusions and rapid postoperative mobilization. The high number of grafted coronary arteries indicates complete revascularization in most patients, which is known to be a significant predictor of long-term event-free survival.
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Introduction |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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Material and methods |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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Operation and CPB
Standard operative procedures included median sternotomy and CPB with a two-stage cannula in the right atrium and one cannula in the ascending aorta. The aorta was cross-clamped while the distal anastomoses were completed. Myocardial protection consisted of intermittent antegrade administration of cold blood cardioplegic solution or crystalloid cardioplegic solution (St. Thomas' Hospital solution no. 2). Anastomosis between the in situ left internal mammary artery and left anterior descending artery, supplemented with saphenous vein grafts, was performed most often. The proximal vein anastomoses were constructed during partial occlusion of the ascending aorta while the patient was being rewarmed.
The CPB was performed with a Stöckert roller pump with a pulsatile flow control (PFC III; Stöckert Instrumente GmbH, Munich, Germany) at a flow rate of 2.4 L/m2 per minute. Mild hypothermia (blood temperature, 32 to 34°C) was instituted immediately after the start of bypass. Two heparin-coated systems were used exclusively during the entire period of investigation; the Carmeda Bio-Active Surface (Medtronic Inc, Minneapolis, MN) system and the Duraflo II equipment (Baxter Healthcare Corp, Bentley Laboratories Division, Irvine, CA).
A reduced dose of heparin (Nyco Pharma, Oslo, Norway), 150 IU/kg, was given for systemic anticoagulation. The activated clotting time (HemoTec, Englewood, CO) had to exceed 250 seconds before CPB was started, and supplemental doses were administered if necessary to maintain this target activated clotting time. Activated clotting time was repeatedly determined during CPB, after protamine administration, and 2 hours postoperatively. For neutralization of heparin, a bolus dose of protamine (protamine sulfate [Novo Nordisk, Baksvard, Denmark]), 1.3 mg/100 IU heparin, was given. The cannulas were removed before reversal of the anticoagulation. Each circuit was examined visually for evidence of clots or fibrin formation after the operation. An additional protamine dose was considered if postoperative bleeding was more than 1.5 to 2 mL/kg bodyweight during the first 2 postoperative hours.
Blood salvage
The blood conservation protocol of the institution, previously described in detail [9], was applied to all patients. The main steps included removal of autologous blood before bypass for retransfusion after bypass (if the patient's preoperative hemoglobin concentration was adequate, usually more than 120 g/L), intraoperative and postoperative retransfusion of the oxygenator and circuit contents (without cell processing), and postoperative autotransfusion of shed mediastinal blood up to 18 hours postoperatively. The amount of postoperative bleeding from the time of sternal closure until the drains were removed was recorded. If possible, platelet inhibitors such as aspirin were discontinued 7 days preoperatively. Normovolemic anemia was accepted to a hematocrit level of 0.25 postoperatively; a level below this was considered an indication for allogeneic red blood cell transfusion.
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Results |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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Operation and CPB
The activated clotting time before starting bypass was median 280 seconds (range, 225–554 seconds). The patients received a median of four (range, 1–9; mean 4.5 ± 1.2) distal anastomoses. At least one internal mammary artery anastomosis was constructed in nearly all patients (99.7%). The median aortic cross-clamp time was 34 minutes (range, 6–88 minutes) and pump time was 54 minutes (range, 11–163 minutes). There were no technical complications related to the CPB, and no clots were noted in the circuits.
Postoperative course
The patients were weaned from the ventilator a median of 1.5 hours (range, 0–320 hours) postoperatively (Table 2).
Within 5 hours, 99.2% of the patients were extubated. Forty-six patients (1.8%) were reexplored for postoperative bleeding. The threshold for reexploration was low (mediastinal drainage > 250 mL/hour for 2 hours), to avoid transfusion of allogeneic blood products. Three patients (0.1%) had a reoperation for graft failure, and 3 patients were assisted by an intraaortic balloon pump (IABP) postoperatively. Nineteen patients (0.8%) received inotropic drug therapy for more than 30 minutes postoperatively. Episodes of atrial fibrillation in patients with preoperative sinus rhythm were encountered in 28.4%. Considering the low systemic heparinization, there were no clinical indications of increased risk for thromboembolic complications. Both the incidences of neurologic events and perioperative myocardial infarctions were low (Table 2). On the fourth postoperative day, 83% of the patients were able to walk stairs or ambulate outside the hospital, and on the fifth day, 91% of the patients were physically ready for discharge. Seven patients (0.28%) died during their hospital stay.
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Comment |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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Perfusion with heparin-coated circuits attenuates blood activation and preserves organ function during and after cardiac operations [2–4]. Further, the heparinized surfaces enhance the thromboresistance and allow a lower level of anticoagulation to be used. Several clinical reports have shown that less postoperative bleeding occurs and requirements for bank blood transfusions are reduced when the amount of systemic heparin is decreased [5–8]. As an integrated part of our blood conservation protocol, the use of heparin-coated circuits and low systemic anticoagulation resulted in a transfusion rate of less than 5% in our patients. Transfusion of allogeneic blood and blood products is known to carry several complications [11], and we assume that the absence of transfusion-related morbidity may be an important factor for an uneventful recovery after cardiac operation.
From a technical point of view, there were no events or problems related to the low systemic heparinization in combination with heparin-coated circuits. However, in a previous study we found some clots in the cardiotomy reservoir after CPB in 2 patients who had redo operations [12]. No detectable side effects were seen, but after that time, we used a full heparin dose in this subgroup of patients. Other authors [13] have also recommended a full heparin dose in valve operations, and therefore, reduced heparinization should be restricted to first-time CABG patients.
Fast postoperative rehabilitation after cardiac operation has medical and financial benefits. Early tracheal extubation is an important step to initiate a fast postoperative recovery and can reduce the need for conventional intensive care to a small number of patients [14]. Early extubation improves postextubation intrapulmonary shunt fraction [15] and can prevent oversedation and resultant depression of the respiratory center, which prolongs intensive care unit stay. The short time needed for ventilatory support in our patients compares well with the results obtained in patients operated on without the heart-lung machine. In fact, in most reports of off-pump techniques [1], the patients are most often extubated several hours later than our median time of 1.5 hours. Also, regarding physical rehabilitation, the patients recovered quickly, and more than 90% of the patients were medically ready for hospital discharge within 5 days after the operation.
The duration of the CPB time and ischemic time certainly influenced the negative effects of extracorporeal circulation. Activation of blood cells and the coagulation, fibrinolytic, and complement systems increased with time [16]. It has also been demonstrated that the CPB time is a determinant for prolonged mechanical ventilation after CABG [17]. It might therefore be suggested that shortening the time on bypass might play a role in preserving organ function, particularly the brain, kidneys, and lungs. With regard to the ischemic stress imposed on the myocardium, studies have shown that the duration of ischemic time is an independent risk factor for development of postoperative myocardial infarction, starting relatively early after aortic cross-clamping [18]. Therefore, efforts should be made to plan the surgical procedures in a way that reduces the ischemic and pump times to a minimum. This practical point is rarely discussed in the literature and may be underestimated as a factor for an uneventful clinical course. However, speed of the operation should never compromise the aim of complete revascularization.
Coronary bypass with CPB and cardiac arrest give the surgeon access to all parts of the heart, and there are no restrictions for complete revascularization. Operation on an empty heart provides uncompromised selection of the best sites for grafting and optimal conditions for microvascular anastomsis. In the present series, the mean number of distal anastomoses was 4.5, ranging from 1 to 9, indicating a high rate of complete revascularization. This is often in contrast to most published series with off-pump techniques, which report significantly fewer grafted arteries [1, 10]. The role of complete revascularization has repeatedly been reported to have a significant effect on long-term morbidity and survival [19, 20]. It should be emphasized that, regardless of short-term benefits, including costs and hospital stay, the primary goal for all treatment protocols must be uneventful long-term survival for the patients.
In summary, the present study found that CABG using CPB seldom required complicated and costly resources. Indeed, most patients were not real candidates for intensive care unit facilities after 3 to 4 hours. Heparin-coated circuits in combination with reduced anticoagulation has been shown to improve the clinical course, and the present results compare well with those reported using off-pump techniques. There was limited need for bank blood transfusions, few postoperative complications, short time for postoperative ventilatory support, and the patients could be rehabilitated physically after a few days. The high rate of completeness regarding revascularization should warrant an optimal chance for long-term event-free survival.
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Acknowledgments |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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References |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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m Holen E., Tangen G., et al. Completely heparinized cardiopulmonary bypass and reduced systemic heparin; clinical and hemostatic effects. Ann Thorac Surg 1995;60:365-371.m Holen E., Tangen G. Consistent non-pharmacologic blood conservation in primary and reoperative coronary artery bypass grafting. Eur J Cardiothorac Surg 1995;9:30-35.[Abstract]
m Holen E., Tangen G., Abdelnoor M. Effects on coagulation and fibrinolysis with reduced versus full systemic heparinization and heparin-coated cardiopulmonary bypass. Circulation 1995;92:2579-2584.This article has been cited by other articles:
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  V. Mazzei, G. Nasso, G. Salamone, F. Castorino, A. Tommasini, and A. Anselmi Prospective Randomized Comparison of Coronary Bypass Grafting With Minimal Extracorporeal Circulation System (MECC) Versus Off-Pump Coronary Surgery Circulation, October 16, 2007; 116(16): 1761 - 1767. [Abstract] [Full Text] [PDF]
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 K. T. Lappegard, J. Riesenfeld, O.-L. Brekke, G. Bergseth, J. D. Lambris, and T. E. Mollnes Differential Effect of Heparin Coating and Complement Inhibition on Artificial Surface-Induced Eicosanoid Production Ann. Thorac. Surg., March 1, 2005; 79(3): 917 - 923. [Abstract] [Full Text] [PDF]
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K. T. Lappegard, M. Fung, G. Bergseth, J. Riesenfeld, and T. E. Mollnes Artificial surface-induced cytokine synthesis: effect of heparin coating and complement inhibition Ann. Thorac. Surg., July 1, 2004; 78(1): 38 - 44. [Abstract] [Full Text] [PDF]
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