Branch-first Sun's procedure: early experience in patients with aortic dissection and aortic aneurysm

Despite great progress in concepts and surgical technique, arch replacement remains a challenge for most cardiac surgery centers. The classic Sun's procedure (total arch replacement using four-branched graft with stented elephant trunk implantation) has achieved good results in arch replacement in cases of type A aortic dissection and become the standard treatment for type A aortic dissection in our center.[1,2] The branch-first technique has been reported by some surgeons. In most cases, the three arch branches were reconstructed under cardiopulmonary bypass (CPB) or deep hypothermia circulatory arrest. We began applying the branch-first Sun's procedure 1 year ago.[3] The three arch branches were bypassed without CPB in most patients. The lowest temperature at circulatory arrest was also elevated. Here we report our early experience with branch-first Sun's procedure in both elective and emergency settings. From July 2017 to December 2018, consecutive patients with aortic dissection and aortic aneurysm in elective and emergency settings were retrospectively identified in the Center of Cardiac Surgery at Beijing Anzhen Hospital. Thirty-six patients with aortic dissection and aortic aneurysm treated with the branch-first Sun's procedure were enrolled in this observational cohort study. Patients’ demographic data, concomitant aortic root repair, the average of CPB time and aortic cross-clamp time, and early post-operative outcomes are shown in Table 1.Table 1: Characteristics of 36 patients with aortic dissection and aortic aneurysm treated with the branch-first Sun's procedure.The procedure was conducted under general anesthesia. Near-infrared reflectance spectroscopy was used. A Y-graft (InterGard, France or Vascutek, Inchinnan, Scotland) is made on the table. The main trunk is usually 12 or 14 mm in diameter. The size of the side arm is usually 8 or 10 mm in diameter. The right axillary artery and right femoral artery are cannulated with 22- or 24-Fr cannulas. The two cannulas are connected to two heads of a bifurcated arterial line to establish a temporal femoral-axillary bypass. With a beating heart and without CPB, the innominate artery, the left common carotid artery (LCCA) and the left sub-clavian artery were connected to the Y-graft one by one either in an end to end way or in an end to side fashion. The right atrium is then cannulated with a two-stage cannula and CPB is started. An ascending graft is chosen according to sino-tubular junction size. The proximal anastomosis is performed first. When the temperature is lowered to around 28°C, flow to the femoral artery stops. Flow to the right axillary artery is maintained at about 10 mL/kg/min with the left radial artery pressure kept at 40 to 60 mmHg. The arch is opened and the aorta is transected proximal to the innominate artery or between the innominate artery and the LCCA. A frozen elephant trunk (Cronus; MicroPort Medical Co, Ltd, Shanghai, China) is deployed into the arch and descending aorta. The proximal sewing ring and native aorta are connected with the distal end of the ascending graft by a continuous suture using 4-0 or 3-0 polypropylene. Systemic perfusion is resumed after the distal anastomosis is completed. The main trunk of the Y-graft is trimmed to the proper length, and its proximal end is bevelled. An oval fenestration is created on the right lateral aspect of the ascending graft. The main trunk is anastomosed with the ascending graft in an end-to-side fashion [Figure 1]. Finally, the heart is resuscitated after deairing.Figure 1: (A) Pre-operative CTA of a patient with an ascending and arch aneurysm. (B) Post-operative CTA of the same patient. CTA: Computed tomography angiography.In the present study, the 30-day mortality rate of patients with an aortic dissection and aortic aneurysm underwent the branch-first Sun's procedure was 5.6%. One patient had a brain infarction (2.8%) and two patients had temporary paraplegia post-operatively (5.6%). The mean CPB and cross-clamp time were 172.4 and 94.3 min, respectively. The lowest nasopharyngeal temperature was 27.0°C (27.0 ± 1.0), while the lowest bladder temperature was 28.2°C (28.2 ± 1.1). Different branch-first techniques have been reported. The patch or island technique was reported by Ergin et al.[4] The trifurcate or double Y-graft was first used by Spielvogel et al.[5] Matalanis reported a branch-first technique with a modified trifurcate graft (adding a perfusion branch).[6] CPB time and aortic cross-clamp time were shorter in our study than in the other studies. In the classic Sun's procedure, right axillary cannulation is used for arterial perfusion. The arch is replaced with a four-branched graft. In the branch-first technique, the right axillary artery and femoral artery are cannulated. A Y-graft and a straight graft (ascending graft) are used instead of a four-branched graft to replace the arch. In the classic Sun's procedure, all five anastomoses are performed under CPB. The sequence of anastomosis is proximal aorta, distal aorta, LCCA, left sub-clavian artery, and innominate artery. In contrast, in the branch-first technique, three arch branches are bypassed without CPB. Only three anastomoses are performed under CPB. In the classic Sun's procedure, during circulatory arrest, the flow to the left hemisphere depends on the integrity of the Willis circle. With the branch-first technique, the entire brain is perfused during circulatory arrest. In the classic Sun's procedure, during distal open aortic anastomosis, the nasopharyngeal temperature is set to 25°C.[1,2] In the branch-first technique, since the entire brain has a blood supply during the distal open anastomosis, the nasopharyngeal temperature was only lowered to around 28°C (https://links.lww.com/CM9/A134). Comparing with our former experience, we found that our results are acceptable. The 30-day mortality rate of the current study was 5.6%. In the classic Sun's group, the 30-day mortality rate was 7.8%.[2] One patient had a brain infarction (2.8%), while two patients had temporary paraplegia post-operatively (5.6%). In the classic Sun's group, the mean CPB time and cross-clamp time were 201 and 111 min, respectively,[2] while in the present study, they were 172.4 and 94.3 min, respectively. Less CPB time and higher temperature may result in less coagulopathy. The early results of the branch-first Sun's procedure are encouraging. Our findings bring us closer to the goals of reducing CPB time and morbidity rates of hypothermia. Future studies with long-term outcomes, more patients, and longer follow-up periods are needed to validate our findings. The present study has several limitations. First, it was performed in a single center and enrolled a relatively small number of patients. Second, there was no long-time follow-up. However, the present study demonstrated that the branch-first Sun's procedure may result in better outcomes in patients with aortic dissection and aortic aneurysm. Conflicts of interest None.