Minimally Invasive Hybrid Treatment of Acute Type I Aortic Dissection

Abstract

After traditional treatment of acute type I aortic dissection, the possible persistence of residual false lumen in the untouched distal aorta can increase the risk of death.

This case report presents an example of single-stage complete hybrid repair of acute type I aortic dissection via surgical interposition of an ascending aortic tube-graft and reconstruction of the supra-aortic branches to enable circulatory inflow from the ascending aortic graft, which was followed by endovascular stenting of the arch and of the descending and thoracic aortic segments. This procedure was performed with partial sternotomy and without circulatory arrest, to improve early and late outcomes.

Unfortunately, there is no extensive experience with application of the technique described here, and we are contributing a report of only a single case. Nevertheless, we hope that this description of a single-stage complete repair of aortic dissection might lead to further application and eventually to fewer deaths in patients with acute type I aortic dissection. We suggest this approach for use especially in high-risk patients.

The current treatment of type I aortic dissection usually involves complex procedures performed with the patient under circulatory arrest.^1,2 This report presents a technique for single-stage, minimally invasive, complete hybrid repair of acute type I aortic dissection without circulatory arrest.

Case Report

In June 2010, type I aortic dissection was diagnosed in a 36-year-old man (Fig. 1), and an emergent operation was planned. A synthetic vascular graft with 4 branches was prepared preoperatively by anastomosing the proximal ends of two 9-mm tube-grafts to the right arm of a bifurcated (18/9-mm), collagen-impregnated, knitted-Dacron graft (Datascope Intervascular, now MAQUET Vascular Interventions, MAQUET Cardiovascular, LLC; Wayne, NJ).

Fig. 1 Preoperative computed tomographic angiogram shows type I dissection, with arrows indicating the dissection flap at A) the ascending and descending aorta and B) the aortic arch.

With the patient under general anesthesia, we opened the mediastinum through an upper J sternotomy. Cardiopulmonary bypass (CPB) with moderate hypothermia (32 °C) was initiated via cannulation of the right axillary artery (RAA) and the right atrium. The cross-clamp was placed at the most distal part of the ascending aorta, just below the brachiocephalic trunk. The ascending aorta was replaced with a 34-mm Dacron tube-graft. The proximal anastomosis was performed at the sinotubular junction and the distal anastomosis was performed proximally at the brachiocephalic trunk. Both proximal and distal anastomoses were reinforced on the external border of the aortic wall by a felt strip with continuous 4-0 polypropylene sutures. No hemostatic glue was used.

Next the aortic cross-clamp was removed. The proximal end of the previously prepared branched graft was anastomosed to the Dacron tube-graft, and the 2 distal arms were anastomosed to the brachiocephalic trunk and the left common carotid artery. Then, the RAA cannula was transferred to the 4th branch, and perfusion was continued through this 4th branch. After warming, the patient was weaned from CPB and decannulated. The CPB and aortic cross-clamp times were 109 and 55 minutes, respectively.

Afterward, the 3rd branch of the graft was anastomosed to the left subclavian artery (Fig. 2). Starting distally via the right femoral artery, we passed 2 Talent® endovascular stent-grafts (Medtronic, Inc.; Minneapolis, Minn) (the first, 36 mm × 20 cm and the second, 38 mm × 15 cm) through the orifice of the previously anastomosed Dacron graft into the descending and ascending aorta, where we deployed them at first proximally, and then distally, to the level of the diaphragm (Fig. 3). A completion angiogram revealed optimal device placement, patency of the supra-aortic vessels, and no patency of the false lumen.

Fig. 2 Illustration of the replacement of the ascending aorta with a 34-mm Dacron tube-graft, and of concomitant supra-aortic revascularization. Proximal anastomosis was performed to the sinotubular junction, and distal anastomosis was performed proximally to the brachiocephalic trunk.

Fig. 3 Illustration of the stent-graft placement through the distal aorta. The endovascular stent-graft was deployed in the ascending and descending aorta through the diaphragmatic level via the right femoral artery, using the previous Dacron graft as a landing zone.

The postoperative course was uneventful, and the patient was discharged from the hospital on the 10th postoperative day. A computed tomogram at the end of the first postoperative month revealed patency of the bypass grafts and of the endovascular stent-graft, with no false-lumen patency (Fig. 4). At the 1-year follow-up appointment, no clinical problem was observed.

Fig. 4 Postoperative computed tomographic reconstruction shows the branched graft originating from the ascending aorta and the implanted stent-graft in the aortic arch and the ascending and descending aorta.

Discussion

After traditional treatment of acute type I aortic dissection, the possible persistence of residual false lumen in the untouched distal aorta can increase the risk of death.

In this report, we describe a minimally invasive, single-stage, complete hybrid repair of acute type I aortic dissection: ascending aortic surgical repair via tube-graft interposition and surgical reconstruction of the supra-aortic branches (in order to create circulatory inflow from the ascending aortic graft) was followed by standard retrograde endovascular stenting of the arch and of the descending and thoracic aorta. This was performed with partial sternotomy and without circulatory arrest, to improve early and late outcomes.

For decision-making in such a procedure, determining the size of the anastomosed ascending aortic graft and the implanted endovascular stent is crucial. The ascending aortic graft must fit the aortic annulus to enable proper valve function; however, it can be kept within the upper limits of the annulus size to afford a greater diameter (if needed) for the distal stents. The size of the stent should be determined by the size of the grafts that form the proximal landing zone, but also by the size of the diseased aortic segment in which the stent will be implanted. The oversizing ratio of the stent should be reduced in a patient who has dissection (in comparison with aneurysmal disease), due to the increased risk of perioperative rupture.

In most acute dissections, the distal thoracic aorta is probably not dilated, so this approach to determining size suits most patients. However, the distal thoracic or abdominal aorta can also be aneurysmal in a small group of patients with acute dissection; or the dissection might have risen from an already aneurysmal aorta. In these circumstances, after the technique described here has been performed, the visceral abdominal arteries can be temporarily bypassed to provide extra-anatomic inflow circulation from the ascending aortic graft, while the abdominal aorta is repaired with retrograde implantation of a stent. Alternatively, the most distal stent can be left in elephant-trunk fashion, to await a staged procedure that will include a retrograde extra-anatomic bypass to provide inflow from the iliac vessels, so that retrograde stenting or a traditional thoracoabdominal open approach can be performed.

Unfortunately, there is no extensive experience with application of the technique described here, and we are reporting only a single case. Nevertheless, we hope that this description of a single-stage complete repair of aortic dissection might lead to further application and eventually to a decrease in the mortality rate of patients with type I acute aortic dissection. We suggest this approach for use especially in high-risk patients.