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J Thorac Cardiovasc Surg 2008;135:527-532
© 2008 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
Escorts Heart Institute and Research Centre, New Delhi, India
Received for publication April 28, 2007; revisions received October 5, 2007; accepted for publication October 19, 2007. * Address for reprint: Yugal K. Mishra, PhD, Escorts Heart Institute and Research Centre, Okhla Road, New Delhi 110025, India. (Email: dryugal{at}yahoo.com).
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Abstract |
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Methods: Between January 1996 and December 2005, 332 patients underwent reoperative off-pump coronary artery bypass grafting. Data were collected regarding the preoperative, intraoperative, and postoperative clinical course of all patients. These were compared with similar data obtained from patients who had undergone conventional coronary reoperation during this period.
Results: Two hundred ninety-six (89.2%) male and 36 female patients underwent reoperative off-pump coronary artery bypass. Of these, 265 (79.8%) patients underwent multivessel bypass through a median sternotomy, an anterolateral thoracotomy was performed in 63 (19%) patients, and a posterolateral thoracotomy was performed in 4 (1.2%) patients. The early mortality for patients undergoing off-pump surgery was lower than for those undergoing conventional reoperations (3.3% vs 5.5%, P = .066). Those who had undergone off-pump reoperations had less need for prolonged ventilation or prolonged inotropic support and had shorter intensive care unit and hospital stays than patients who had undergone redo coronary artery bypass grafting.
Conclusion: For many patients requiring coronary reoperations, off-pump techniques are safe and feasible. Complete revascularization was achieved in at least 75% of patients in an unselected population, with mortality and perioperative event rates that are comparable with those of conventionally performed coronary reoperations.
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Coronary artery bypass grafting (CABG) is a well-established therapy for patients with coronary artery disease, and the results of primary operations are relatively good. However, many patients have recurrent symptoms, and some require reoperation. Although some authors have observed similar rates of mortality and morbidity for both primary coronary artery surgery and reoperative coronary bypass,1
many other groups have found that mortality and morbidity are higher during coronary reoperation.2,3 Traditionally, coronary reoperation has been performed during cardiopulmonary bypass with the aorta crossclamped and the heart arrested by means of cardioplegia (redo CABG). Recently, techniques of performing coronary artery surgery off pump have been developed. At this institution, we are routinely performing primary off-pump CABG (OPCABG),4 with excellent results.5 The reports of the application of off-pump techniques to coronary reoperations (redo OPCABG) for either single-vessel or multivessel disease are few.6-10 The aim of this retrospective study was to analyze our experience with redo OPCABG.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Table 1. All patients had symptomatic coronary artery disease that could not be managed by using medical therapy. Apart from routine investigations, specific preoperative studies included coronary angiography, transthoracic echocardiography, pulmonary function testing, posteroanterior and lateral chest radiography, and, more recently, contrast-enhanced computed tomography of the chest.
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Selection of Surgical Approach
Median sternotomy
All patients planned for multivessel revascularization underwent sternotomy.
Anterolateral thoracotomy
Anterolateral thoracotomy was used as a technique to avoid the morbidity of sternal re-entry, especially in sicker, often older patients with additional comorbidities who required left anterior descending coronary artery (LAD) bypass, and as an elective, minimally invasive procedure for those who required LAD grafting.
Posterolateral thoracotomy
Posterolateral thoracotomy was used for grafting the obtuse marginal vessels in patients with patent left internal thoracic artery (LITA)–LAD grafts.
Surgical Technique
Median sternotomy was the surgical approach used in 265 cases. The redo sternotomy and mediastinal dissection were performed as recommended previously,11 essentially by using an oscillating saw, initial exposure of the aorta and right atrium, the "no-touch" technique for previously placed grafts, and careful progression of the dissection on the left ventricle to identify and preserve previously placed thoracic artery–coronary artery grafts. The entire heart was mobilized in all cases. Indications for conversion to redo CABG included bleeding at sternal re-entry, hemodynamic instability during mediastinal dissection, or the finding of small-caliber, diffusely diseased coronary targets, rendering off-pump methods technically difficult. The patient was given 3 mg/kg heparin. To facilitate distal anastomosis, use was made of commercially available suction-based cardiac stabilization devices, and a CO2 blower and intraluminal shunts were used routinely. The proximal aortic anastomoses were performed by using a partial, side-biting, atraumatic vascular clamp. The effects of heparin were reversed with protamine, and graft flows were checked with Doppler probes. The redo CABG procedure was performed during aortic crossclamping with both antegrade and retrograde delivery of cold blood (4:1) cardioplegia, moderate systemic hypothermia, and a terminal hot shot.
Anterolateral thoracotomy
After institution of double-lumen endotracheal intubation, the patient was placed in the right lateral decubitus position with the pelvis externally rotated to 45° to allow access to the femoral artery. A small skin incision was made along the fifth intercostal space between the nipple and the midaxillary line, and the fifth intercostal space was opened. The thoracotomy was extended anteriorly or posteriorly to facilitate the operation. With the lung deflated, the LITA was harvested, as described elsewhere.12 The pericardium was then opened anterior to the phrenic nerve. Limited adhesiolysis, sufficient to expose the target vessels, was performed, and then the anastomosis was performed by using standard techniques.
Posterolateral thoracotomy
The fifth intercostal space was used to enter the chest. The pericardium was palpated to locate and avoid old vein grafts if present and was opened posterior to the phrenic nerve. After distal anastomosis, proximal anastomosis was performed on the descending aorta by routing the grafts anterior to the pulmonary hilum.
Data were collected regarding the preoperative, intraoperative, and postoperative clinical course of all patients. The operative notes were used to evaluate the choice and number of grafts. Perioperative myocardial infarction was defined as any new Q wave or loss of R wave on the electrocardiogram or a significant increase in creatine kinase–myocardial fraction levels (>40 U/L). Postoperative bleeding was defined as the need for re-exploration for persistent bleeding. Cerebrovascular accident was defined as a coma lasting longer than 24 hours, transient ischemic attack, or neurologic deficit lasting longer than 72 hours. Renal failure includes both an increase of serum creatinine value to twice preoperative levels and a need for dialysis. The patients who required intraoperative conversion from redo OPCABG to redo CABG were included in the redo CABG group for final analysis.
Statistical analysis was performed with SPSS software (SPSS, Inc, Chicago, Ill). All clinical data are expressed as means ± standard deviations. Categorical values were compared by means of the 
2 test, and the Mann–Whitney test was used to calculate the differences in continuous variables between the 2 groups. The mean number of grafts per patient in each group was compared by using the paired Student t test.
The use of these data for research was approved by the institutional review board.
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Results |
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Table 2) reveal that redo OPCABG is feasible in most patients, regardless of the coexisting disease or the urgency of clinical presentation. Note that 35.5% required urgent operations, 7.6% had an intra-aortic balloon pump, and 16% had significant left main disease. Preoperatively planned redo OPCABG required intraoperative conversion to redo CABG in only 11% of cases, and in only 8% of cases was institution of intra-aortic balloon pump support needed. There was no difference in outcome between patients requiring intraoperative conversion to redo CABG and those preoperatively selected for redo CABG. An average of 2.17 grafts per patient could be placed in those requiring multivessel bypass, with 57% receiving LITA–LAD anastomoses (
Table 3). In the group undergoing anterolateral thoracotomy, all 68 patients received LITA–LAD grafts without the need for cardiopulmonary bypass.
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Table 4), and 1 patient died after anterolateral thoracotomy. In the multivessel redo OPCABG group, morbidity also was low: postoperative myocardial infarction, 4.8%; renal failure, 0.6%; cerebrovascular accident, 0%; and prolonged ventilation, 7.5%.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In recent years, however, the number of patients undergoing coronary reoperation has reached a plateau in some institutions (
Figure 1).1,2 This is the result of routine use of the LITA for grafting of the LAD, better management of saphenous venous conduits, and evolution in antiplatelet and statin therapy. Hence patients who require coronary reoperations are currently older, with more extensive coronary artery disease and poorer left ventricular function.2
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There are several factors that contribute to this: hazards during sternal re-entry, hemodynamic instability during mediastinal dissection, inadvertant damage to patent grafts, ischemia caused by embolization of atheromatous debris from venous conduits, and inadequate myocardial protection caused by difficulties in delivering cardioplegia in the face of native and conduit stenoses. Additionally, parallel to progression of coronary artery disease, there might be more extensive aortic atherosclerotic disease.14
OPCABG aims at complete revascularization without subjecting the patient to the ill effects of extracorporeal circulation, cardioplegia, or aortic cannulation. Some benefits of OPCABG over CABG at primary operation have been noted: decreased incidence of atrial fibrillation, transfusion needs, inotrope requirements, respiratory infections, ventilation time, intensive care unit stay, and hospital stay.15 However, concerns regarding the completeness of revascularization and graft patency remain.
There are few published reports of the application of off-pump techniques to coronary reoperations. Many of these pertain to single-vessel coronary targets,16,17 and experience with multivessel redo OPCABG is limited.6-9
This report documents the largest and most comprehensive experience of the use of off-pump techniques for reoperative coronary artery bypass. Compared with patients usually encountered in North America, our patient cohort is younger and thus perhaps at less risk during coronary reoperation, and this fact could have influenced our results. Nonetheless, although this is a retrospective and nonrandomized study in which surgeons selected the choice of procedure, we believe that the large and unselected patient population described helps to establish the safety and feasibility of redo OPCABG for routine clinical use.
Safety and Feasibility
We have shown that redo OPCABG can be performed safely in 61.7% of patients presenting for coronary reoperation, regardless of the comorbid disease, and in a wide range of clinical presentations of the patient. The overall mortality of 3.3% in our patients compares favorably with that of most published studies on conventionally performed coronary reoperation. Sabik and colleagues1 reported a mortality rate of 4.4% for their patients undergoing first reoperation; Di Mauro and associates7 reported that their mortality rate was 4.2%. We have also found that among our patients, the performance of redo OPCABG results in low rates of perioperative myocardial infarction, renal failure, and cerebrovascular accidents and allows for reasonably swift recovery of these patients. The present study was not designed to be a true comparison of outcome between redo OPCABG and redo CABG. We sought to establish the safety and efficacy of redo OPCABG in a large series of patients undergoing coronary reoperation, especially in light of the limited worldwide experience with this technique. The comparison presented sheds some light on the spectrum of cases that can be performed safely by using off-pump techniques. However, other authors have compared redo OPCABG with redo CABG directly.6-9 In all of these studies, the trend is toward a reduction in mortality and morbidity in the redo OPCABG groups. It merits emphasis, however, that in all of these studies, patients were not randomized to receive either procedure, and criteria for selection for redo OPCABG was variable. Moreover, these were small studies, and hence these trends have not become statistically significant. Recently, blood transfusion requirements have been shown to be reduced when redo OPCABG is performed.18 None of the studies could show a significant difference in atrial fibrillation, renal function, cerebrovascular accident, or other minor adverse clinical parameters.
Adequateness of Revascularization
Complete revascularization is the main goal of primary coronary bypass, and it is reasonable to assume the same is true of coronary reoperation. Studies have demonstrated that incomplete myocardial revascularization negatively affects outcome after primary operations.19 The main concerns regarding primary OPCABG involve completeness of revascularization achieved and graft patency. In the setting of coronary reoperation, Di Mauro and associates7 found higher rates of incomplete revascularization in patients undergoing redo OPCABG (17.7% vs 5.9%, P < .01) when compared with redo CABG and showed that incomplete revascularization was an independent risk factor for cardiac death and cardiac mortality at 5 years. Tugtekin and coworkers8 used the index of completeness of revascularization (preoperative planned/performed anastomosis) to compare redo CABG and redo OPCABG. They found a higher incidence of complete revascularization in their redo CABG group (86.9% for redo CABG vs 48.6% for redo OPCABG, P < .01). In the study by Czerny and colleagues,6 in which redo OPCABG was targeted to culprit coronary targets (target vessel revascularization), because of significant difference in completeness of revascularization, a higher incidence of recurrent angina was noted during a 5-year follow-up period. From these studies, there is some evidence of less complete revascularization when performing coronary reoperations by using off-pump techniques.
The application of a thoracotomy approach toward coronary reoperations appears to be more accepted.20,21 After primary bypass, progression of disease and venous graft attrition often lead to a situation in which a reoperative bypass is required in the presence of patent internal thoracic artery grafts. The posterolateral thoracotomy approach allows revascularization of the obtuse marginal vessels while avoiding the hazards of sternal re-entry, with its potential for injury to the patent grafts. Additionally, in cases in which a vein graft might have been placed on the LAD during the first operation, the anterolateral thoracotomy approach allows LITA–LAD grafting without sternal re-entry. Furthermore, this approach also allows for the performance of hybrid revascularization safely, as well as transmyocardial laser revascularization.22
Certain limitations of this study must be addressed. This was a nonrandomized retrospective study that has allowed the feasibility of redo OPCABG to be established. However, a true comparison of redo OPCABG with redo CABG would require a randomized controlled trial with well-defined criteria for selection of patients for redo OPCABG. These studies are necessary to obtain evidence as to which preoperative factors could predict preoperatively that a patient would have a successful off-pump procedure.
In summary, this report describes the versatility of the various techniques of redo OPCABG and demonstrates that for a majority of patients requiring coronary reoperations, off-pump techniques are safe and feasible. Complete revascularization was achieved in at least 75% of patients in an unselected population, with mortality and perioperative event rates that are comparable with those of conventionally performed coronary reoperation.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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This article has been cited by other articles:
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  D. Morales, E. Williams, and R. John Is resternotomy in cardiac surgery still a problem? Interact CardioVasc Thorac Surg, September 1, 2010; 11(3): 277 - 286. [Abstract] [Full Text] [PDF]
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 A. Zacharias, T. A. Schwann, C. J. Riordan, S. J. Durham, A. S. Shah, M. Engoren, and R. H. Habib Late outcomes after radial artery versus saphenous vein grafting during reoperative coronary artery bypass surgery J. Thorac. Cardiovasc. Surg., June 1, 2010; 139(6): 1511 - 1518. [Abstract] [Full Text] [PDF]
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