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Ann Thorac Surg 2000;70:1026-1029
© 2000 The Society of Thoracic Surgeons

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Supplement: cardiothoracic techniques & technologies

Off-pump redo coronary artery bypass grafting

^a Escorts Heart Institute and Research Centre, New Delhi, India

Address reprint requests to Dr Mishra, Escorts Heart Institute and Research Centre, Okhla Rd, New Delhi 110025, India
e-mail: ehirc{at}vsnl.com

Presented at the Sixth Annual Cardiothoracic Techniques and Technologies Meeting 2000, Ft Lauderdale, FL, Jan 27–29, 2000.

	Abstract

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Background. Conventional redo coronary artery bypass grafting is associated with significant morbidity. The danger of reoperation is mainly in reopening the sternum and in the manipulation of the heart and the old grafts. Therefore, off-pump redo coronary artery bypass grafting with a patient-specific approach in selected cases seems an ideal technique.

Methods. Between October 1995 to September 1999, 50 patients with mean age of 61.8 ± 8 years underwent reoperative coronary artery bypass grafting without cardiopulmonary bypass. Isolated left internal mammary artery (LIMA) to left anterior descending artery (LAD) anastomosis was carried out in 25 cases through left anterior minithoracotomy. In 1 patient LIMA was grafted on a previous vein graft to LAD, which was critically stenosed proximally but distal anastomosis was patent. In another case LIMA was grafted to Ramus intermedius branch. Midsternotomy approach was used to carry out LAD and right coronary artery grafting in 21 cases. In 2 patients a posterolateral thoracotomy approach was used to bypass obtuse marginal branches without cardiopulmonary bypass; in these cases proximal anastomosis was performed on the descending aorta.

Results. Mortality rate was 4% (2 deaths). Two patients sustained perioperative myocardial infarction. No patient was reexplored for hemorrhage and 38 patients did not require homologous blood transfusion. Sixteen patients underwent check angiogram and all of them were found to have patent redo grafts. Cardiac recovery room stay was 22 ± 7 hours and hospital stay 5 ± 2 days.

Conclusions. In selected patients, reoperative coronary artery bypass grafting can be performed without cardiopulmonary bypass with a low perioperative morbidity and mortality and satisfactory graft patency.

	Introduction

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With the increasing number of patients who have undergone coronary artery bypass grafting (CABG), the incidence of reoperative CABG is also increasing. Reoperative procedures have revealed technical obstacles that differentiate them from primary procedures. These problems include (1) difficulties with reentry; (2) potential for cardiac and conduit injury during dissection; (3) availability of conduit; (4) management of patent vein grafts; (5) myocardial protection; and (6) bleeding and blood products use [1].

As the overall experience with reoperative CABG has increased, alternative strategies have evolved in an attempt to lower the operative risks, which exceed those of initial revascularization [2]. These strategies include different techniques for reentry, strict avoidance of graft manipulation to minimize the risk of graft atheroembolism, and modification in the method of myocardial protection depending on the status of the native coronary circulation and patency of vein or internal mammary artery (IMA) grafts. As an alternative method of "myocardial protection" and to obviate the inherent risks of cardiopulmonary bypass (CPB), we carried out reoperative CABG without CPB in a carefully selected group of patients. In this article we review our experience of redo CABG without CPB.

	Material and methods

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From October 1995 to September 1999, 50 patients at our institution underwent reoperative CABG without CPB. During the same time frame 1,278 patients underwent primary off-pump CABG. Unstable angina was present in 21 patients whereas 29 had chronic angina refractory to medical therapy. Seven patients in this group had previously undergone coronary angioplasty procedures after primary CABG.

The group of patients consisted of 46 men and 4 women with the mean age of 61.8 ± 8 years. Twenty-two patients had had prior myocardial infarction and 2 patients had congestive heart failure at the time of surgery. Mean left ventricular ejection fraction was 40 ± 7.2%. Other risk factors present in this group of patients are shown in Table 1. All patients underwent their first reoperation for myocardial revascularization. Target sites were left anterior descending coronary artery (LAD) 46, previously placed saphenous vein graft (SVG) to left anterior descending artery (LAD) 1, Ramus intermedius 1, right coronary artery 6, and obtuse marginals 4.

A second surgical team harvested an appropriate length of saphenous vein or radial artery as required. When the IMA was to be used, it was prepared after the lysis of adhesions. The patients underwent systemic heparinization with 1.5 mg/kg body weight of heparin, and the proximal saphenous vein or radial artery to aortic anastomosis was constructed with running 6-0 Prolene suture (Ethicon, Somerville, NJ) using partial aortic occlusion. When the LAD was grafted, exposure was obtained by elevating the heart on a laparotomy pad, and the hemodynamic response was observed. Mild hypotension was corrected easily with volume or vasopressor administration, usually ephedrine or norepinephrine. For segmental stabilization of myocardium adjoining the target area an Octopus tissue stabilizer (Medtronic, Minneapolis MN) or Genzyme stabilizer (Genzyme surgical, Tucker, GA) was used. Sometimes intracoronary or aortocoronary shunts were used to minimize myocardial ischemia.

In 25 patients who had either patent graft or ungraftable distal targets in circumflex and posterior descending artery territory, the left internal mammary artery (LIMA), which was not used in primary surgery, was utilized to bypass LAD by minimally invasive direct coronary artery bypass (MIDCAB) surgery. A fourth occasionally fifth intercostal incision was made, beginning 2 to 3 cm lateral to the sternal border on left side. The pleural cavity was entered and the lung packed out of the field. The costal cortilages were not divided and the ribs were not resected. Before harvesting the LIMA, a standard small thoracic retractor was positioned, the pericardium identified and incised, and the LAD was located. Identification of the LAD often is easier in a redo MIDCAB procedure because the LAD almost always has been bypassed previously and the vein graft acts as a guide.

If MIDCAB grafting is ill advised because of anatomic considerations or inadequate exposure, this approach is abandoned. However, if the MIDCAB approach appears feasible, then the operation proceeds using the MIDCAB system (CardioThoracic Systems, Inc, Cupertino, CA), which consists of two disposable retractors and a regional cardiac wall stabilizer. With the help of LIMA lift retractor adequate length of LIMA is harvested and LIMA to LAD anastomosis done after systemic heparinization with 1.5 mg/kg body weight of heparin. Details on the MIDCAB technique are described in earlier publications [3, 4]. In 1 patient LAD was not graftable hence LIMA was used to bypass the intermedius branch through the same incision after dissecting a further length of LIMA proximally. In another patient LIMA was grafted on a previously placed SVG to LAD that was blocked proximally but distal anastomosis was patent and distal LAD was small and intramyocardial. In 4 patients in the MIDCAB group who had blocked SVG to circumflex territory, hybrid percutaneous transluminal coronary angioplasty (PTCA) to obtuse marginal (OM) branches was carried out after 5 days of MIDCAB procedure to achieve complete myocardial revascularization. In another 4 patients transmyocardial laser revascularization (TMLR) was used in circumflex and posterior descending aorta (PDA) territory along with MIDCAB to revascularize the ischemic myocardium because there were no suitable distal targets available either for CABG or PTCA.

Two patients had patent LIMA to LAD but SVGs to OMs were blocked, hence these patients underwent off-pump OM grafting using local immobilization technique via a posterolateral thoracotomy approach. Inflow was from descending aorta. Following double-lumen endobronchial intubation, patients were placed in the right lateral decubitus position with the pelvis corkscrewed to permit femoral–femoral CPB if the need arose. A posterolateral thoracotomy was performed in the fifth interspace. The pericardium was opened posterior to the phrenic nerve and adhesions taken down along the OM distribution. Dissection of posterior mediastinal adhesion was carried out to expose the descending aorta in the region of the inferior pulmonary ligament, which was thoroughly mobilized.

Octopus tissue stabilizer tentacles were placed straddling and parallel to the marginal target vessel. A proximal vessel snare was placed, an arteriotomy carried out beyond the previous graft anastomosis, and saphenous vein or radial artery grafting performed as the case was. The proximal anastomosis was performed in the descending thoracic aorta using a partial occluding clamp for vascular control. The grafts lay in a gentle loop under the mobilized inferior pulmonary ligament.

Study protocol
We reviewed surgical results (mortality, morbidity, and intensive care unit and hospital stay) and intraoperative LIMA grafts patency by Doppler flow measurement in patients who underwent the MIDCAB procedure. Short-term follow-up graft patency in 16 redo cases was done by check angiogram on the fifth postoperative day.

	Results

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
There were two hospital deaths (4%). Both the patients died after the MIDCAB procedure and preoperatively were in congestive heart failure and were put on intraaortic balloon pump support. One of them underwent operation after failed PTCA to diseased LAD vein graft. Another patient had acute myocardial infarction with ventricular arrhythmia; he was put on intraaortic balloon pump but remained unstable and hence was taken up for operation. Both the patients had low cardiac output postoperatively and died on the first and second postoperative days, respectively.

Two patients sustained perioperative myocardial infarction (4%). No patient required reoperation for hemorrhage. Thirty-eight patients required no blood products. The average blood requirement in the remaining 12 patients was 1.2 units per patient. There were no wound infections. Cardiac recovery room stay was 22 ± 7 hours and hospital stay 5 ± 2 days. In 27 patients who underwent the MIDCAB procedure, intraoperative Doppler flow study of grafted LIMA was performed and in all 27 patients adequate diastolic LIMA flow was found. For the 16 patients who gave the consent for check angiography, a coronary angiogram was done on the fifth postoperative day; in all of them adequate functioning redo grafts were found. In 4 of these patients who had occluded primary OM vein grafts hybrid PTCA to diseased SVG to circumflex coronary artery was also done along with check angiography. Four patients had MIDCAB and TMLR to posterolateral and inferior wall and tolerated the procedures well.

	Comment

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Reoperative coronary procedures are an increasing part of most practices, with excellent results reported by several investigators [5, 6]. Although the mortality associated with redo operations has decreased the morbidity remains significant, particularly as surgeons are asked to take care of more complex patients [7, 8]. Economic forces, aimed at decreasing morbidity, have intensified efforts in all surgical fields to focus on less invasive techniques. Unlike general thoracic and gynecologic operations, a reduction in reoperative coronary morbidity depends primarily on avoiding the detrimental physiologic and cerebral effects of CPB, rather than simply creating alternative, smaller-access incision.

Reoperative CABG without CPB requires less operating time and a shorter postoperative hospital stay, which translates into a reduction of hospital costs. There were fewer bleeding complications with this technique as almost three fourths of patients in present series required no blood products and no patient was reexplored for excessive mediastinal hemorrhage. Although construction of distal anastomosis on the beating heart is technically more demanding and required a short period of coronary occlusion, the observed incidence of postoperative myocardial infarction was low (4%).

For redo patients, the MIDCAB procedure avoids manipulation of patent grafts and mobilization of adhesions from previous operation. Favorable results of the MIDCAB procedure for redo CABG to revascularization of the LAD using the LIMA have been reported by various authors [9, 10]. We have carried out MIDCAB procedures in 27 patients who came for redo CABG. In all 27 cases adequate length of LIMA was dissected with the help of the LIMA lift refractor. In 25 patients LIMA was grafted to LAD distal to previous SVG. In 1 patient LAD distal to SVG was small and intramyocardial, hence LIMA was grafted to in situ SVG, which was patent distally but stenosed proximally. In another patient SVG to LAD was patent. In this case LIMA was grafted to ramus intermedius branch, which had developed disease after primary CABG. In all 27 patients, LIMA flow was evaluated with Doppler flow measurements and revealed adequate diastolic LIMA flow, which is a reflection of patent distal anastomosis.

The combined use of MIDCAB with PTCA, otherwise known as the "hybrid procedure," was practiced in 4 patients in the present series. A LIMA to LAD anastomosis was followed by angioplasty to diseased SVGs to circumflex territory. Check angiograms to recently placed LAD anastomosis was also done during angioplasty and in all of them redo anastomosis was found to be patent. We regard this combined approach as a safe, viable alternative for the treatment of high-risk patients with stenosis or occlusion of previously placed bypass grafts, which allows complete revascularization without resternotomy and CPB.

In 4 patients in the MIDCAB group there were no distal targets in the circumflex and posterior descending artery territory suitable either for CABG or PTCA, hence to achieve complete myocardial revascularization we combined LIMA to LAD anastomosis with TMLR to the posterolateral and inferior wall.

The technique of off-pump OM revascularization was combined successfully with the thoracotomy route for reoperative CABG surgery by Baumgartner and colleagues [11]. In the present series we used posterolateral left thoracotomy in 2 patients to bypass two OM branches in both cases with saphenous vein and radial artery conduits without CPB. Proximal anastomosis was carried out on the descending aorta as both the patients had patent LAD graft. We found this method reliable and successful in both cases, and we believe that off-pump OM grafting by the thoracotomy approach is a useful adjunct for redo CABG, particularly in patients with patent IMA grafts.

Modifications in all aspects of the coronary reoperation will continue to evolve as surgeons are confronted by an ever-increasing number of patients requiring reoperative revascularization. Reoperative CABG without CPB is yet another technique that allows the operation to be tailored to the needs of the individual patient. This technique is no panacea, but in highly selected patients reoperative CABG can be performed safely and effectively without CPB.

	Acknowledgments

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Special thanks to Ms Preeti Saxena for excellent secretarial assistance.

	References

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 

1. Cosgrove D.M., III Is coronary reoperation without the pump an advantage?. Ann Thorac Surg 1993;55:329.[Medline]
2. Foster E.D., Fischer L.D., Kaiser G.C., Myers W.O., Principle investigators of CASS and their associates. Comparison of operative mortality for initial and repeat coronary artery bypass grafting. The coronary artery surgery study (CASS) registry experience. Ann Thorac Surg 1984;38:563-570.[Abstract]
3. Mishra Y.K., Mehta Y., Juneja R., et al. Mammary coronary artery anastomosis without cardiopulmonary bypass through a minithoracotomy. Ann Thorac Surg 1997;63:S114-S118.
4. Juneja R., Mehta Y., Mishra Y., Trehan N. Minimally invasive coronary artery surgery. Anesthetic consideration. J Cardiothorac Anesth 1997;11:123-124.
5. Loop F.D., Lytle B.W., Cosgrove D.M., et al. Reoperation for coronary atherosclerosis. Ann Surg 1990;212:378-385.[Medline]
6. Weintraub W.S., Jones E.L., Craver J.M., et al. In hospital and long-term outcome after reoperative coronary artery bypass graft surgery. Circulation 1995;92(Suppl):1150-1157.
7. He G.-W., Acuff T.E., Ryan W.H., He Y.-H., Mack M.J. Determinants of operative mortality in reoperative coronary artery bypass grafting. J Thorac Cardiovasc Surg 1995;110:971-978.[Abstract/Free Full Text]
8. Fanning W.J., Kakos G.S., Williams T.E. Reoperative coronary artery bypass grafting without cardiopulmonary bypass. Ann Thorac Surg 1993;55:486-489.[Abstract]
9. Miyaji K., Wolf R.K., Flege J.B. Minimally invasive direct coronary artery bypass for redo patients. Ann Thorac Surg 1999;67:1677-1681.[Abstract/Free Full Text]
10. Boonstra P.W., Grandjean J.G., Mariani M.A. Reoperative coronary bypass grafting without cardiopulmonary bypass through a small thoracotomy. Ann Thorac Surg 1997;63:405-407.[Abstract/Free Full Text]
11. Baumgartner F.T., Gheissari A., Panagiotides G.P., et al. Off-pump obtuse marginal grafting with local stabilization. Ann Thorac Surg 1999;68:946-948.[Abstract/Free Full Text]

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