Cerebral Perfusion through Separate Grafts for Repair of Acute Aortic Dissection with Torn Arch

Abstract

We have modified the technique of cerebral perfusion through anastomosed grafts for repair of acute arch dissections that require total arch replacement. We have performed this operation on a 71-year-old man with an acute type-A dissection and an arch tear between the orifices of the brachiocephalic arteries. We used 2 separate grafts for the brachiocephalic arteries and minimized brain ischemia by initiating antegrade selective cerebral perfusion after the 1st anastomosis. The patient had an excellent outcome. This method is simple and provides effective protection. Cerebral ischemic time can be kept under 30 minutes without need of a sophisticated pump setup or a multibranched graft. This affords extra time in case the surgeon encounters an unexpected lesion in the arch. (Tex Heart Inst J 2001;28:288–91)

There are several different methods of brain protection during aortic surgery. Each of these techniques—deep hypothermic circulatory arrest or antegrade or retrograde cerebral perfusion (or both) in combination with deep or moderate hypothermia—has some advantages over the others, and these advantages can be supplementary if the techniques are used in combination. Lately, the results of using antegrade selective cerebral perfusion (ASCP) during total aortic arch replacement have improved remarkably. ^1,2 However, antegrade cerebral perfusion requires the cannulation of the brachiocephalic arteries: in such an instance, multiple cannulae or balloon-tip catheters encumber the operative field; and the use of a multibranched graft, or a separate pump head and heat exchanger, makes the procedure complex. The alternative, deep hypothermic circulatory arrest without ASCP, should not exceed 40 minutes (preferably 30) at 12 to 15 °C, if subtle brain injury is to be avoided. ³

Case Report and Technique

A 71-year-old man with no relevant medical and surgical history developed a sudden chest pain. A diagnostic work-up revealed an acute type-A aortic dissection. The patient was taken to surgery. After performing a median sternotomy and a right groin incision, we administered systemic heparin. The right atrium and the femoral artery were cannulated, the former with a single 2-stage cannula. After instituting cardiopulmonary bypass and cross-clamping the ascending aorta, we induced cardioplegia with cold blood infused directly through the coronary ostia and through a catheter in the coronary sinus. The left ventricle was vented through the right superior pulmonary vein.

While the patient was being cooled to 18 °C, his ascending aorta was explored. There was a flap in the proximal aorta, but no intimal tear, and the aortic valve was competent. We repaired the dissected layers of the proximal ascending aorta with gelatin-resorcin-formalin glue and anastomosed a 22-mm Dacron graft end-to-end with this segment, buttressing the seam with a strip of Teflon felt.

We cooled the patient further until his rectal temperature reached 15 °C and the oxygen saturation level of his internal jugular vein exceeded 95%. After circulatory arrest, the arch was explored. The origin of the intimal tear was between the orifices of the innominate artery and the left carotid artery (Fig. 1A). This tear extended to the descending aorta and became circumferential distal to the left subclavian artery. Because of the location of the intimal tear, it was not possible to resect the arch as an island encompassing the 3 great vessels. Therefore, the innominate artery was dissected free and amputated from the arch. A 10-mm Dacron graft was anastomosed to it in an end-to-end fashion (Fig. 1B). Two perfusion lines with straight arterial cannulae were attached to the main arterial pump line by using 2 Y connectors. In order to fill the innominate artery graft with blood retrogradely for de-airing, we initiated a short period of retrograde cerebral perfusion through the 2-stage cannula in the right atrium, at a rate of 600 mL/min. One of the perfusion lines with a straight cannula was inserted into this graft through its open end and tied with heavy silk. The perfusion line to the femoral artery was clamped. Antegrade selective cerebral perfusion was initiated through the innominate artery graft at a rate of 600 mL/min to maintain a radial artery pressure of 50 mmHg, while the rest of the body was still in circulatory arrest. There was back-bleeding from the left carotid and left subclavian arteries, so they had to be clamped. A button containing the orifices of the left carotid and left subclavian arteries was prepared, and a 14-mm Dacron graft was anastomosed to it in an end-to-end fashion. The 2nd perfusion line with a straight cannula was inserted into this graft through its open end and tied with heavy silk (Fig. 1C). The flow rate was increased to 1200 mL/min to achieve a perfusion pressure of 50 mmHg in both radial arteries. While the ASCP through both cerebral grafts continued and the lower body was in circulatory arrest, we resected the intimal tear and anastomosed a 22-mm tubular graft (with an elephant trunk technique) to the descending aorta. The other end of this graft was then sewn to the proximal aortic graft in an end-to-end fashion (Fig. 1D). The graft to the left carotid/subclavian button was anastomosed to this arch graft while ASCP was continued through the innominate artery graft. After the evacuation of air, perfusion of the lower body and the left carotid/subclavian button was initiated via the femoral artery cannula, and the arch graft was cross-clamped proximal to the anastomosis of the left carotid/subclavian graft. During warming, the graft to the innominate artery was sewn to the ascending aortic graft (Fig. 1E). The cross-clamp was removed and the heart was defibrillated. The patient was weaned from cardiopulmonary bypass with some inotropic support. Hemostasis was attained. The patient received blood and fresh frozen plasma, 5 units each. The cerebral ischemic time was 25 minutes; the antegrade selective cerebral perfusion time, 80 minutes; and the deep hypothermic circulatory arrest time, 105 minutes.

Fig. 1 Steps in attaching the grafts. A) Ascending aortic replacement is completed; the intimal tear is seen to originate between the orifices of the innominate artery and the left carotid artery. B) The innominate artery is dissected free and a 10-mm Dacron graft is anastomosed to it in an end-to-end fashion during circulatory arrest. Antegrade selective cerebral perfusion is begun through the innominate artery graft. C) A 14-mm Dacron graft is anastomosed to the button containing the left carotid and left subclavian arteries. Both grafts are used for antegrade cerebral perfusion. D) A 22-mm tubular graft with an elephant trunk is anastomosed to the descending aorta. This graft is then sewn to the proximal aortic graft in an end-to-end fashion. E) After attachment of the left carotid/subclavian button graft to the new aortic arch, perfusion of the lower body and of the left carotid and left subclavian arteries is initiated via the femoral artery cannula. The arch graft is cross-clamped proximal to the left carotid/subclavian anastomosis. The graft to the innominate artery is sewn to the ascending aortic graft during warming.

Discussion

The concept of cerebral perfusion through the anastomosed graft was first reported by Ergin and associates, ⁴ and has been widely used in their patients. It is not always possible to make a single button of arch vessels, especially in cases of a torn arch. Yaginuma and colleagues ⁵ reported a technique that requires the completion of 3 anastomoses before antegrade cerebral perfusion can be initiated. With our technique, absolute brain ischemic time is the period between the initiation of deep hypothermic circulatory arrest and the initiation of antegrade selective perfusion through the innominate artery graft. When our patient awoke 12 hours after the operation, he did not have any permanent or temporary neurologic dysfunction; temporary dysfunction has been described by Ergin's group ⁶ as a consequence of inadequate cerebral protection and subtle brain injury. The patient was discharged 9 days after the operation without any complication other than a mild fungal glossitis. Postoperative angiography showed a satisfactory repair (Fig. 2). This procedure is technically simple and it yields secure anastomoses and easy hemostasis. The size mismatch between the grafts and arteries is minimal. Cerebral ischemic time can be kept under 30 minutes without need of a sophisticated pump setup or a multibranched graft. This affords extra time in case the surgeon encounters an unexpected lesion in the arch.

Fig. 2 Postoperative digital subtraction angiogram shows the completed repair.