Asian Cardiovasc Thorac Ann 2001;9:51-52
© 2001 Asia Publishing EXchange Pte Ltd
Management of Graft Injury During Repeat Coronary Bypass Surgery
Sudhansu S Bhattacharya, MCh,
Shrikant D Kole, MCh,
Dilip H Oswal, MCh
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Bombay Hospital & Medical Research Centre Mumbai, India
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For reprint information contact: Sudhansu S Bhattacharya, MCh Tel: 91 22 363 5885 Fax: 91 22 208 0871 Bombay Hospital & Medical Research Centre, Bombay Hospital Avenue, 12 New Marine Lines, Mumbai 400020, India.
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Abstract
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A vein graft to the left anterior descending coronary artery was damaged during reoperation for further coronary bypass on an 82-year-old man. A temporary shunt was established to deliver retrograde cardioplegia before instituting cardiopulmonary bypass for further vein grafting.
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Introduction
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During a repeat coronary artery bypass grafting (CABG) operation, a vein graft may be damaged. Several methods of temporary shunting have been used for graft injury causing a significant reduction in flow. We describe a relatively simple and time-saving solution for management of problems arising from such an injury.
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Case Report
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An 82-year-old man who had received vein grafts to the left anterior descending artery (LAD), obtuse marginal, and distal right coronary artery (RCA), was admitted with angina (Canadian Cardiovascular Society class III) 3 years later. Chest radiography revealed a cardiothoracic ratio of 0.55 with congested lung fields. Adherence of the right ventricle to the sternum was excluded. Coronary angiography revealed 90% obstruction of the vein graft on the LAD, distal to the aortic anastomosis. The grafts on the obtuse marginal and RCA were patent. The native vessels showed progression of disease with significant lesions in the LAD, posterior descending artery, and the posterolateral branch of the RCA. The left ventricular (LV) ejection fraction was 0.3 and LV end-diastolic pressure was 28 mm Hg.
Repeat CABG was undertaken via a median sternotomy. The aorta and right side of the heart were dissected first. During dissection of adhesions at the front of the heart, the vein graft on the LAD was damaged resulting in marked ischemic changes in the anterior electrocardiogram (ECG) leads, including a 10-mm ST-segment depression. It was not feasible to carry out primary repair of the graft because of adhesions and intimal plaques. In view of the ECG changes and poor LV function, it was decided to restore graft flow with a temporary shunt and deliver retrograde cardioplegia rather than institute cardiopulmonary bypass (CPB). A 16F cannula (Cavafix 375; B. Braun, Melsungen, Germany) was inserted into the distal cut end of the vein graft and a tie was placed around the graft; a bulldog clamp was applied to the proximal end. A size-14 antegrade cardioplegia needle (DLP, Inc., Grand Rapids, MI, USA) was inserted into the ascending aorta. The proximal end of the Cavafix cannula was attached to the Luer-Lok end of the cardioplegia cannula, using a male-to-male extension line (Figure 1
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Figure 1. Photograph of the temporary shunt used to restore graft flow. A = Cavafix cannula, B = male-to-male extension line, C = cardioplegia cannula.
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In view of this event and the patient's age, it was decided not to use the internal mammary artery (IMA) for CABG. Normothermic CPB was instituted with standard cannulation. Normothermic antegrade and retrograde cardioplegia was delivered; the temporary shunt was removed after delivery of retrograde cardioplegia. Saphenous vein grafts were constructed to the posterior descending artery and the posterolateral branch of the RCA. Vein grafts were anastomosed sequentially to the first diagonal artery and the LAD. Both cut ends of the damaged graft were fixed securely and CPB was terminated uneventfully. Postoperatively, there was no evidence of ischemic injury to the heart. The patient was discharged from hospital after 3 weeks.
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Discussion
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A patent IMA pedicle during a repeat CABG procedure poses specific problems. Various techniques have been described for protection of the IMA pedicle from injury during subsequent operations. These techniques include positioning the pedicle in the left chest to prevent adhesion to the sternum, and wrapping it in a polytetrafluoroethylene membrane.1,2 In most cases, the previous operation notes do not mention the lie of the IMA pedicle. Preoperative radiography and angiography can give some idea of the position of the pedicle. Occasionally, a surgeon may encounter damage to a patent IMA pedicle or vein graft during reoperation and various intraoperative techniques have been described to prevent this injury. These include separation of the posterior table of the sternum with an osteotome, and even prophylactic use of CPB via both femoral vessels before the sternotomy.2 Following injury to a patent IMA graft, Coltharp and colleagues3 described cannulation of the cut end of the IMA with a soft bulb tipped cannula and perfusion via a line taken from the arterial line. However, institution of CPB and procurement of a special cannula may result in considerable delay before graft flow can be restored.
Severe ECG changes or hemodynamic instability may result from injury to an IMA or vein graft to an important vessel. We feel that institution of CPB imposes too long a delay and may not completely relieve ischemia in the myocardium supplied by the damaged graft. Delivering cardioplegia retrogradely achieves the same functional outcome as re-grafting the vessel. The treatment of a damaged graft must be immediate restoration of blood supply to the affected area. Conventional teaching is that only injury to patent grafts can cause problems. However, this case showed that injury to a graft that was 90% blocked could also precipitate problems in a patient with poor LV function. We do not consider angiographic evidence of patency or blockage as proof of the functional importance of the graft. Due care must be taken during dissection, whether the grafts are angiographically patent or stenosed. In the event of either IMA or vein graft injury, the technique described is simple, time-saving, and effective. We routinely keep a Cavafix cannula in the operating room during all repeat CABG procedures.
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References
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Gillinov AM, Casselman FP, Lytle BW, Blackstone EH, Parsons EM, Loop FD, et al. Injury to a patent left internal thoracic artery graft at coronary reoperation. Ann Thorac Surg 1999;67:382–6.[Abstract/Free Full Text]
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Vaughn CC. Protective wrapping of internal thoracic artery. Ann Thorac Surg 1999;67:567–8.[Abstract/Free Full Text]
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Coltharp WH, Decker MD, Lea JW IV, Petracek MR, Glassford DM Jr, Thomas CS Jr, et al. Internal mammary artery graft at reoperation: risks, benefits, and methods of preservation. Ann Thorac Surg 1991;52:225–9.[Abstract]
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Abstract
Introduction
