Patients

The subjects were 13 patients (12 men and 1 women) with acute Stanford type A aortic dissection involving the aortic arch, they underwent extensive primary repair of the thoracic aorta by means of ascending aorta replacement combined with open placement of triple-branched stent graft from January 2011 and October 2011.The ethics committee of our Hospital approved the procedure. We obtained written informed consent from each patient. The average age was 46±8.2 years; approximate range, 30~58years. The diagnosis was based on electricbeam computed tomography and echocardiography. The 13 patients were selected for extensive primary repair of the thoracic aorta by means of ascending aorta replacement combined with open placement of triple-branched stent graft because they satisfied following inclusion and exclusion criteria. The indications were acute Stanford type A aortic dissection with (1) the intimal tear located in transverse arch or proximal descending aorta that could not be resected by hemiarch replacement, (2) serious involvement of the arch vessels.

The 13 patients selected for triple-branched stent graft placement satisfied the additional criteria [11]: (1) the diameters of the native aortic arch and arch branches were 10-20% smaller than those of the corresponding stent grafts, (2) the distances between two neighbouring arch branched were equal to the distances between two corresponding sidearm stent grafts, (3) no history of carotid artery disease, (4) no aortic aneurysm in arch or proximal descending aorta and (5) all three arch branch ostia could be seen clearly from the arch true lumen through the transverse incision of the distal ascending aorta. The positions and the diameters of the native aortic arch and arch branches are different in different cases; we measured these data by preoperative three-dimensional computed tomography and then chose the optimal size for individuals.

Description of the device

The triple-branched stent graft is a branched 1-piece graft consisting of a self-expandable nitinol stent and polyester vascular graft fabric (Yuhengjia Sci Tech Corp Ltd, Beijing, China). It comprised a main graft and 3 sidearm grafts. The main graft was tapered and flexible enough to conform to the curved aortic arch. The tapered main graft was 145 mm in length, 30 mm in proximal diameter, and 26 mm in distal diameter. At its proximal end, there was a 10-mm-long stent-free sewing Dacron tube. The first sidearm graft was 35 mm long and 14 or 16 mm in diameter. Both the second and third sidearm grafts were 25 mm long and 12 or 14 mm in diameter. The distance between 2 neighboring sidearm grafts was 3 mm. The main graft and 3 sidearm grafts were individually mounted on 4 catheters and restrained by 4 silk strings (Figure 1).

Surgical technique

All procedures were performed with patients under general anesthesia. The arterial blood pressure of both the upper and lower limbs was monitored, and a probe for transesophageal echocardiographic monitoring was inserted. A median sternotomy was performed in all patients. cardiopulmonary bypass was established by 2 venous cannulas through the right atrium and 2 arterial return cannulas placed in the femoral and right axillary arteries. A left ventricular vent was inserted through the right superior pulmonary vein. Systemic cooling was initiated while the ascending aorta, aortic arch vessels, and descending thoracic aorta were exposed. The ascending aorta was clamped at the base of the innominate artery and transected just above the sinotubular junction. Cardioplegia was infused directly into the both coronary arteries. After the internal surface of the ascending aorta and the aortic valve were examined, proximal manipulations were performed. Then, the ascending aorta was anastomosed to a short segment of a straight graft (Hemashield Gold; Meadox Medicals, Oakland, New Jersey) Systemic cooling progressed until the patient’s nasopharyngeal temperature reached 20°C, and the pharmacologic agents (thiamylal sodium, phenytoin, and mannitol) were administered for brain protection [12] in addition to ice packs placed around the head, before circulatory arrest. After circulatory arrest had been instituted, the ascending aorta was unclamped and the aortic arch was opened. The innominate artery, left common carotid artery, and left subclavian artery were identified. Through the transverse incision of the ascending aorta, the main graft of the triple-branched stent graft was inserted into the true lumen of the arch and proximal descending aorta, and then each sidearm graft was positioned one by one into the aortic branch. Once the main graft and sidearm grafts were properly positioned, the restraining strings were withdrawn and then the main graft and sidearm grafts were deployed (Figure 2). Finally, after the release of the aortic arch stent, inserted into 40-degree saline gauze in the lumen, the shape memory alloy stent fully opened adherent, and 3–0 Prolene suture reinforced with Teflon band near the innominate artery, left subclavian artery and the main vessel stent through the suture arterial wall. The transected distal stump of the ascending aorta was reconstructed by the inner proximal stent-free Dacron tube of the main graft, and subsequently continuous anastomosis to the Dacron tube graft was made in an end-to-end fashion. The air was carefully flushed out from the triple-branched stent graft with femoral and right axillary blood return. Then, antegrade systemic perfusion from the branch of the Dacron tube graft was started, and the patient was rewarmed.

Follow-up

All patients were contacted by telephone or direct interviews in our department after discharge. All patients followed up prospectively by means of contrast-enhanced computed tomography scan and general examination on the following schedule: before discharge, 3 months after the operation.

Operative data

13 patients had hypertension without effective control. The primary intimal tears were located in the ascending aorta in 9 patients, in the arch in 3 patients, and in the proximal descending aorta with retrograde extension of the dissection into the arch and the ascending aorta in 1 patient. Placement of the triple-branched stent graft into the true lumen of the proximal descending aorta, arch, and 3 arch vessels was successful in all 13 patients and could be finished within 5 to 20 minutes. Concomitant procedures were Bentall operation in 2 patients, and coronary artery bypass in 1 patients. The mean cardiopulmonary bypass time was 138.40±47.75 minutes, aortic cross-clamp time was 70.60±28.94 minutes, and arrest time was 28.60±12.48 minutes.

Computed tomographic scans

The postoperative angio CT scans and echocardiographic examinations showed that all stent grafts were opened and not kinked, there was no space or blood flow surrounding the triple-branched stent graft. No sidearm graft occlusion was found (Figures 3,4).

Follow-up

The follow-up was 100% complete. There were no late deaths and no need for reoperation during the mean follow-up of 9 ± 2 months (range, 3–12 months). No neurological complications were observed.

First: less anastomosis, simplified the operation

In our technique, extensive primary repair of the thoracic aorta could be performed simply by both open placement of the triple branched stent graft into the proximal descending aorta, arch, and 3 arch vessels and graft replacement of the ascending aorta, which could reduce the risk and technical difficulties of extensive thoracic aorta repair to close to those of the conventional ascending graft replacement with open distal anastomosis. In the hybrid procedure of Kato [5], careful manipulation of the arch and elaborate anastomoses to the distal aortic arch and 3 arch vessels are time-consuming. Moreover performing anastomosis and hemostasis at the descending aorta is usually very difficult. Our open triple-branched stent graft placement technique can reduce such problems. Therefore, cardiopulmonary bypass time, aortic cross-clamp time, and selective cerebral perfusion and lower body arrest time were shorter than in the Kato and Sun’s hybrid technique seen in previous reports [5, 6] and were comparable to those of conventional ascending replacement with open distal aortic anastomosis.

Second: less bleeding

Open triple-branched stent graft placement technique makes it easy to control bleeding, we have observed less bleeding and did not encounter any difficult bleeding. No patient required additional surgery to correct excessive postprocedural bleeding. Three reasons explain this: first, anastomoses to 3 arch vessels were totally avoided; second, the distal aortic anastomosis at the distal ascending aorta, which provided a better surgical view for performing anastomosis and hemostasis; Finally, shorter time on cardiopulmonary bypass and deep hypothermic circulatory arrest contributed to the quick recovery of postoperative blood coagulability.

Finally: less damage to vital organs and quick recovery

With our open triple-branched stent graft placement, as the surgical procedure simplified, the three branches of the aortic arch and descending aorta anastomosis reduced, deep hypothermic circulatory arrest time of significantly shortened, reducing the deep hypothermic circulatory arrest for vital organs such as brain, lung and kidney to avoid postoperative stroke, acute renal failure and dialysis. Reduce the adverse impact on lung function, avoiding the occurrence of acute respiratory insufficiency, reducing respiratory infection. Therefore, all patients had a short time on postoperative mechanical ventilation and a short stay in the intensive care unit and shortened hospital stay in this group. Improvement of prognosis after surgical repair of acute type A dissection is largely dependent on the reduction of complications.

Postoperative CT showed that all sidearm stent grafts were fully opened and no sidearm stent graft endoleak. For these good results, diameters of the 3 sidearm grafts, distances between 2 neighboring sidearm grafts, and proper placement of the triple-branched stent grafts were crucial. For each patient, the diameters of the selected grafts should be 10% to 20% bigger than the diameters of the native aortic arch and arch vessels, respectively [5, 13]. The proper size of each graft was key for quick clot formation and shrinkage of the false lumen and for preventing new intimal trauma resulting from the continuous compression of the oversized stent graft on the dissected and frangible intimal wall [5, 7]. The distances between 2 neighboring sidearm grafts should be approximately equal to the distances between 2 corresponding arch vessels, which would keep sidearm stent grafts from being twisted or kinked after deployment. It is reported that some risks such as postoperative stent graft shifting or kinking may be occur [14]. But in this study, no sidearm graft occlusion was observed because we use 3-0 Prolene suture reinforced with Teflon band near the innominate artery, left subclavian artery and the main vessel stent through the suture arterial wall to prevent the late shift and poor adhesion. The long-term patency of those sidearm grafts should be carefully evaluated.