Type A Aortic Dissection After Coronary Artery Bypass Grafting

Introduction

Aortic dissection is rare after coronary artery bypass grafting. It is a potentially fatal complication of cardiac surgery. Aortic surgery for aortic dissection after previous coronary artery bypass grafting is a challenging procedure. Reoperation may pose problems with thoracotomy, adhesiolysis, and myocardial protection. No standard treatment guidelines exist for chronic aortic dissection after CABG. Some authors suggest surgical treatment in non-stable and medical treatment for stable patients without progression [1,2]. We report the outcome of ascending aortic reoperation after previous CABG and evaluate our management of patent grafts and methods for obtaining myocardial protection.

Case Report

SURGERY:

Cardiopulmonary support was initiated by cannulating the femoral artery and vein on the right side. The cannulation of the right axillary artery was abandoned because of trauma on the right shoulder. Half a dose of heparin was given. At the same time, vena saphena was harvested for LAD bypass. A repeat median sternotomy was conducted. Substernal adhesions were carefully dissected, with particular attention given to the bypass grafts and the enlarged aorta. After completing the dissection, another half dose of heparin was administered, and cardiopulmonary bypass was started. The temperature was lowered to 28°C. The right atrium was additionally cannulated because femoral venous drainage was not sufficient. Dissection was continued in the apical direction. A sequential venous graft from a previous surgery made the secure dissection of adhesions possible only in the apical direction from the graft. Only the distal part of LAD was possible to identify. The LITA graft remained untouched to prevent additional injury. A cut in the ascending aorta exposed an intimal tear near the proximal anastomosis of the 2 great saphenous vein grafts. The false lumen exhibited partial thrombosis. The vein grafts remained patent, and the aortic wall was resected island-like. Antegrade del Nido cardioplegia was given through native ostia and functional bypass grafts. The ascending aorta was clamped immediately before the origin of the right brachiocephalic artery. Teflon felt strips were utilized to create a proximal aortic stump. Subsequently, both proximal and distal anastomoses were executed using a 30-mm Polythese^®ICT prosthesis. The second cardioplegia was given through a cardioplegia cannula inserted in the prosthesis. The venous graft was anastomosed to the apical LAD saphenous vein, and the buttons of the 2 previous vein grafts were anastomosed to the artificial graft. Even after mobilization, the vein graft to RCA was too short, so it was elongated with a new saphenous vein graft in an end-to-end fashion. After all anastomoses were completed, the aorta was declamped. Weaning from the heart-lung machine was uneventful. The circulatory arrest time was 119 min and the total bypass time was 207 min. The postoperative course was uneventful, the patient was extubated on postoperative day (POD) 1, and she left the intensive care unit on POD 2. No significant complications were observed, and she was discharged on POD 9.

Discussion

Ascending aortic dissection (AAD) is an uncommon but potentially fatal complication of coronary artery bypass grafting [3]. Causes include aortic clamping, aortic cannulation, and central anastomosis of the vein grafts during previous surgery [4]. In our case, the dissection site was close to the saphenous graft, but the central anastomoses were intact. We assume that aortic clamping could be the reason for dissection, but this was uncertain due to adhesions and the chronic character of the dissection. The surgery was performed in another center, and there was nothing about intraoperative complications or aortic wall pathologies in the documentation. Surgery of chronic type A dissection following CABG becomes more challenging with functional midline crossing bypass grafts. Reoperations after CABG are still associated with high morbidity and mortality rates. To perform complex surgery with optimal results, it has been proposed that a safe and less invasive surgical strategy must be implemented [5]. The operating quickness and a simplified approach, such as the ‘open IMA technique,’ antero-grade cardioplegia, mild-to-moderate hypothermia, and minimal dissection of the mediastinal structures, were proposed [6]. Adequate cardioplegia is vital for appropriate myocardial protection and gives surgeons enough time to perform complex procedures [7]. In this case, we decided to use del Nido cardioplegia to minimize cardioplegia delivery times. Some recent studies have shown good outcomes using del Nido in a complex cardiac procedure in adult patients [8–10].

Our patient was easily weaned from the heart-lung machine and showed good cardiac function postoperatively.

Conclusions

The development of acute aortic dissection after CABG is a rare and potentially lethal complication, and early diagnosis can be life-saving. There are few reports of it in the literature. No standard surgical strategy guidelines exist for late acute aortic dissection after CABG. Reoperation may pose fatal problems with thoracotomy, site preparation, and myocardial protection. Peripheral cannulation with a half dose of heparin administration prevents thrombosis of the cannula and, at the same time, gives the surgeon time for relatively bloodless and secure thoracotomy and dissection of adhesions. It also shortens cardiopulmonary bypass time and complications related to it. If necessary, cardiopulmonary bypass can be started quickly by giving another half dose of heparin. del Nido cardioplegia is easy to implement, is safe, and offers surgeons enough time without interruptions to fluently perform complex procedures.