Interact CardioVasc Thorac Surg 2007;6:768-771. doi:10.1510/icvts.2007.152884
© 2007 European Association of Cardio-Thoracic Surgery
Patients and complication with off-pump vs. on-pump cardiac surgery – a single surgeon experience
Andreas Rukosujewa,*,
Stefan Klotza,
Christiane Reitzb,
Wiebke Gogartenc,
Henryk Welpa and
Hans H. Schelda
a Department of Thoracic and Cardiovascular Surgery, University Hospital Muenster, Albert-Schweitzer-Str. 33, D-48129 Muenster, Germany
b Department of Epidemiology and Social Medicine, University Hospital Muenster, Muenster, Germany
c Department of Anesthesiology and Intensive Care, University Hospital Muenster, Muenster, Germany
Received 29 January 2007;
received in revised form 8 July 2007;
accepted 30 July 2007
 Presented at the 55th International Congress of the European Society for Cardiovascular Surgery, St Petersburg, Russian Federation, May 11–14, 2006.
*Corresponding author. Tel.: +49-251-83-56111; fax: +49-251-83-48316.
E-mail address: andreas.rukosujew{at}ukmuenster.de (A. Rukosujew).
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Abstract
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Background: Off-pump operations (OPCAB) are growingly used for patients with coronary artery disease (CAD) and may be associated with improved outcomes when compared with coronary artery bypass grafting (CABG) using extracorporeal circulation (ECC), especially in patients with comorbidities. The aim of this study is to compare the intra- and postoperative results of OPCAB complete arterial myocardial revascularization with standard on-pump CABG under respect of comorbidities. Methods: We report about the implementing of the off-pump technique in our institution from November 2004 to May 2006. Sixty-two patients with CABG in off-pump technique were compared to a control group of 129 patients with CABG using ECC. The off-pump technique was mostly used in patients with vascular and pulmonary diseases. All operations were performed by the same surgeon. All off-pumps were performed using both internal thoracic arteries (ITA) or left ITA and radial artery (RA) in T-graft technique, while in the on-pump group only the LITA and saphenous vein were used. The conversion rate from OPCAB to conventional CABG was 3.2% (two patients). Results: Peripheral vascular disease (PVD) and chronic obstructive pulmonary disease (COPD) were significant more often in the off-pump group. Other preoperative risk factors were comparable between the groups. Operation time was significantly longer in the off-pump group. Postoperative symptomatic transient psychotic syndromes were more often in the on-pump group. Outcome was similar, despite significant longer operation time in off-pump group. Conclusion: Off-pump coronary artery surgery can be performed in patients with comorbidities with similar outcome compared to on-pump surgery.
Key Words: Coronary artery bypass grafting (CABG); Arterial revascularisation; Composite T-graft off-pump technique
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1. Introduction
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Off-pump coronary artery bypass grafting (OPCAB) in combination with ‘no aortic touch’ as an alternative procedure to coronary artery bypass grafting (CABG) using the extracorporeal circulation (ECC) was suggested for prevention of aortic wall damage, early postoperative neurological events, renal dysfunction and longer hospital stay [1, 2]. In addition, OPCAB procedures decrease the activation of both coagulation and fibrinolysis in comparison with the standard CABG using the ECC [3]. Arterial composite grafts with sequential grafting technique allows to perform more distal anastomoses with a limited number of grafts to avoid an aortic anastomosis [4].
The aim of this study is to present our first experience with OPCAB complete arterial myocardial revascularisation and to compare the intra- and postoperative results with standard on-pump CABG under respect of vascular and pulmonary diseases.
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2. Patients and methods
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2.1. Patients
From November 2004 to May 2006, 62 patients with CABG in off-pump technique (study group) were compared to a control group of 129 patients with CABG using ECC. Mainly patients with chronic obstructive pulmonary disease (COPD) and/or peripheral vascular disease (PVD) were selected to the study group. All off-pumps were performed using both internal thoracic arteries (ITAs) (46 patients) or radial artery (RA) in combination with the left internal thoracic artery (LITA) (14 patients) in T-graft technique for complete arterial revascularisation. In the on-pump group only the LITA and saphenous veins were used.
Patients with reoperation and acute myocardial infarction were excluded from this study.
2.2. Surgical technique and pharmacologic management
All surgical procedures were performed by the same surgeon (A.R.). Median sternotomy was the cardiac approach in all patients. The ITA was harvested in pedicled form, trying to avoid opening the pleura. The RA in the study group was harvested in a skeletonised fashion and only in a few cases as a pedicled graft. Our standard technique of RA harvesting has been reported previously [5, 6]. Saphenous veins in the control group were harvested using an open or partial minimal invasive approach and stored in heparinised saline solution until use.
Heparin 400 IU/kg was administered in both groups intravenously to achieve an activated clotting time (ACT) above 400 s. Aprotinin (2.5 million kIU) was administered in both groups through a central line direct after pericardiotomy, except for the first twelve off-pump patients. In these patients a cell saver system was used intra- and postoperatively.
In the control group, ECC was started by cannulating the ascending aorta and the right atrium with a two-stage venous cannula. Myocardial protection was achieved by using cold blood cardioplegia in patients with ejection fraction below 40% and HTK solution (Custodiol®) in all other patients. Saphenous vein grafts (SVG) were sutured mostly in a sequential grafting technique using the side branches of the vein transplant. All distal anastomoses were performed with a 7-0 polypropylene running suture. After completion of the distal anastomosis, the aortic clamp was removed and the proximal anastomosis was performed with partial tangential clamping using 5-0 polypropylene sutures.
In the beating heart patient group, traction sutures were applied to the pericardium margin in the left side for exposure of the left anterior descending artery (LAD). Cardiac stabilisation was achieved with a vacuum stabiliser system (Guidant AcrobatTM SUV with Access RailTM Platform, Guidant Corporation, Santa Clara, USA). Elevation of the heart for the exposure of the lateral and posterior wall vessels was obtained with sling support and apical suction (Guidant XposeTM 4 Device, Guidant Corporation, Santa Clara, USA). The Trendelenburg position was not used. Visualisation in the performing of the distal anastomosis was enhanced by using a blower device (Clearview® Medtronic Inc., Minneapolic, USA). Intraluminal shunts (Clearview® Medtronic Inc., Minneapolic, USA [for 1.25–2.0 mm vessels]) were routinely used for grafting of all coronary branches. All peripheral and T-graft anastomoses were performed with an 8-0 polypropylene running suture. The first grafted vessel was the LAD, followed by distal anastomoses with RITA or RA and finally proximal T-graft anastomosis. In two cases, if the LAD was the only open vessel and the other coronary vessels were totally occluded, we performed the first coronary anastomosis with obtuse marginal branches (OM) and posterior descending artery (PDA) to prevent myocardial ischaemia and haemodynamic instability, followed by T-graft anastomosis and finally grafting of LITA to LAD.
Heparin was fully reversed with protamine chloride after completion of revascularisation in both groups. All patients in the study group have received clopidogrel (75 mg/day), aspirin (100 mg/day) and amilodipine (10 mg/day) starting from the first postoperative day.
2.3. Statistical analysis
The paired Student t-test was used to compare groups. Data are expressed as mean±S.D. or median±S.D. A P-value of <0.05 was considered statistically significant. For all pairwise comparisons, Wilcoxon signed-rank was employed to assess significance.
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3. Results
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The conversion rate from OPCAB to conventional CABG with the ECC was 3.2% (two patients). Both patients were from the beginning of our experience with composite T-graft and ‘no aortic touch’ technique. In one case the reason was an intraoperative myocardial infarction, in another patient with pulmonary hypertension heart elevation induced an instable haemodynamic situation. These two patients were included in a separate group.
Age in the study group varied from 44 to 81 years (mean 63.9±10.1) and from 43 to 85 years (mean 67.2±9.7) in the control group (P=0.03). Other preoperative data are shown in Table 1. Risk factors such as body-mass-index, gender, diabetes, creatinine level, left ventricular ejection fraction and EuroSCORE were comparable in both groups (all P=ns). Peripheral vascular disease (PVD 25.0 vs. 7.8%, P=0.001) and chronic obstructive pulmonary disease (COPD 20.0 vs. 9.3%, P=0.04) were significant more often in the off-pump group.
Operation time was significantly longer in the off-pump group (Table 2). The reason was longer preparation time of both ITAs and time for performing of the distal anastomosis. The number of distal anastomoses varied from 2 to 4 (mean 2.6±0.5) in the study group and from 2 to 5 (mean 2.8±0.7) in the control group (P=0.008). Blood transfusions had to be performed in 38% of the cases in the study group and 43% in control group (P=ns). Median duration of ventilation was non-significantly higher in the off-pump group and the time in the intensive care unit was similar in both groups.
Data of the postoperative complications are presented in Table 3. Thirty-day-mortality was 1.7% (one patient) in the study and 2.3% (three patients.) in the control group (P=ns). One patient of the study group died of stroke developed on the first day after operation due to carotid vascular disease (CVD) with total occlusion of carotid artery on one side and 80% carotid stenosis on the other side. Preoperative neurological evaluation of this patient showed good collateral perfusion of the brain, so there was no indication for carotid endarterectomy in this case. However, the severe CVD was the reason for the off-pump revascularisation in this patient. Three patients of the control group died within 30 days. Two patients had low output state and one patient died due to multi-organ failure.
There were no significant differences between groups in the number of bleeding events requiring reexploration. In the study group this was observed only in the first twelve patients where aprotinin was not administrated. Data of postoperative bleeding in the off-pump group depending on aprotinin administration is shown in Table 4. There was a tendency for lower need of red blood cell transfusion in patients receiving aprotinin (P=0.11).
In all patients with left ventricular ejection fraction (LVEF) lower than 30% (three patients of the study group and nine patients of the control gruop) an intraaortic balloon pump (IABP) was implanted pre- or intraoperatively. In three other patients (one patient of the off-pump and two patients of the on-pump group) peri-operative myocardial infarction was the reason for the diastolic augmentation with the IABP.
There were no statistically significant differences in both groups with respect to transient psychosis and sternal infection. However, the data show a tendency for higher frequency of transient psychosis in the control group. Sternal infection requiring reoperation occurred in one patient in the off-pump group after revascularisation with both ITAs and one patient with diabetes and obesity in the on-pump group (Table 3).
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4. Discussion
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The experience in OPCAB with complete arterial myocardial revascularisation and T-graft technique with ‘no aortic touch’ began in our department in November 2004. The clinical benefit of this less-invasive procedure is reduction of postoperative neurological events and prevention of complications associated with the use of the ECC especially in high-risk patients [7, 8]. The use of the composite T-graft allows a multi-vessel revascularisation with arterial grafting and without aortic manipulations [4, 9]. Reasons for choosing the second arterial graft for a composite technique are various. We believe the RITA as a free graft in patients with enlarged and dilated hearts is often not suitable in reaching all target vessel, while the radial artery used in the technique of composite T-graft is superior. Differences in the outcome using LITA in combination with RITA or RA were not observed.
As a main result we could show that OBCAB with complete arterial revascularisation could be performed safely with a low mortality. While many comorbidities were similarly distributed between the groups, PVD and COPD were significantly more often in the off-pump group. This is an indication that OBCAB is mostly used in patients with higher risk in using the ECC. In our opinion there are no contraindications for the off-pump technique, however, we believe that acute myocardial infarction with instable haemodynamics, re-revascularisation and fixed pulmonary hypertension are major limitations for off-pump CABG.
The use of the intraluminal shunt during the distal anastomosis is not a standard procedure in OBCAB and there are different opinions about advantages and benefits of this technique [10]. We think performing off-pump surgery is simpler and safer using intraluminal shunts. This technique prevents not only myocardial ischaemia, it gives excellent exposure to the proximal and distal corners of the anastomosis and, therefore, provides a high quality suture.
Peri-operative haemorrhagic complications and the need for blood transfusions are still one of the major problems in this type of surgery. The use of antifibrinolitic drugs (aprotinin, tranexamic acid, aminocaproic acid) reduces the postoperative blood loss [11, 12]. In our experience, we have learned in the first patients to manage the problem of postoperative bleeding with the use of a cell saver system. The administration of aprotinin was associated with a reduction of intraoperative and postoperative blood loss, red blood cell transfusion and there was no re-exploration for bleeding in the 48 patients in the study group who received aprotinin before revascularisation. In addition, there was also no need for a cell saver system. We believe the tendency to lower the number of red blood cell transfusions in patients with aprotinin administration confirms our present tactics.
Many publications emphasise the advantages of the off-pump surgery in avoiding the inflammatory response of the ECC and thereby reducing major complications, postoperative ventilation time, ICU-stay and mortality [7, 8, 13]. Postoperative transient psychosis was lower in patients with OPCAB compared to on-pump surgery. Although the higher incidence of this complication in the on-pump group was not statistically significant, we believe that a tendency to less postoperative psychosis in patients following OBCAB remains and will be more clearly seen with higher patient volumes in the off-pump population. The trend towards longer time on the ventilator is probably caused by the significant higher incidence of COPD and not by the off-pump surgery.
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5. Limitations
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This study has several limitations. First is not a prospective randomised study. While one of the strengths is the single surgeon experience with a good study comparability, the patients were not randomised to the two groups, but selected individually. Another limitation is the learning curve in implementing this technique. This learning curve affected not only the surgeon, but the intraoperative anaesthesiology and postoperative ICU management, too.
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6. Conclusion
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Off-pump coronary artery surgery can be performed in patients with comorbidities with similar outcome compared to on-pump surgery. Especially in patients with COPD and PVD, OPCAB seems to be most effective.
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Abstract
1. Introduction
