TAR with median sternotomy is a standard procedure for aortic arch surgery because cerebral perfusion is safely assured by antegrade cerebral perfusion and myocardial protection is easily performed. However, surgical exposure is sometimes limited and additional left thoracotomy might be required in cases aortic aneurysm or dissection entry exists beyond the left subclavian artery. In a recent report, extended TAR with the combination of left anterior thoracotomy and upper median sternotomy displayed a higher rate of respiratory complications compared to standard TAR with the median sternotomy [
5]. Thoracic endovascular aortic repair is becoming applied for aortic arch pathologies. In-hospital mortality was reported as 4–5%, and cerebrovascular event occurred in 2–11% after the repair, which was better than the open surgery [
6,
7]. However, 33% of patients underwent aorta-related reintervention during 9 months follow-up and estimated freedom from any aorta and/or non-aorta related reintervention at 12 months was 48 ± 13% [
7]. OSG is considered advantageous compared to total arch replacement because the needs for a distal anastomotic suture and a left thoracotomy are eliminated. Additionally, in contrast to thoracic endovascular repair, stent detachment is minimized [
8]. Historically, OSG was utilized to eliminate the distal anastomosis beyond the left subclavian artery during TAR for acute aortic dissection [
2]. The aortic arch was dissected between the brachiocephalic and left common carotid arteries, and the graft was inserted in the dissected lumen toward the descending aorta, covering the carotid and subclavian arteries. The proximal end of the graft was sutured to the branched non-stented vascular graft, which replaced the ascending aorta and brachiocephalic artery with reconstruction of the brachiocephalic, left common carotid, and subclavian arteries. The frozen elephant trunk technique was introduced in 2001 by Karck et al. to facilitate thrombosis in the space between the graft and aorta, reducing the wall stress of the descending aorta [
9]. The graft was delivered to the descending aorta, and the proximal site of the graft was directly sewn to the native aortic wall with or without ascending aorta and aortic arch replacement. We performed mini-OSG in the patients with aortic arch aneurysm and dissection, which involved the left common carotid and the subclavian arteries. In this initial series, no mortality was observed although one patient developed left hemiplegia. No pseudoaneurysm or endoleakage was observed during 2 to 20 months of follow-up. The mean intraoperative blood loss volume was 587 ml, and the patients were weaned from the ventilator 7.1 h postoperatively. These results suggest that mini-OSG might be an alternative treatment for aortic arch pathologies.
In our initial series of mini-OSG, we solely applied OSG via the aortic arch without graft replacement of the ascending aorta and aortic arch to simplify the procedures (Fig.
1). Preoperative CT revealed that the ascending aorta and aortic arch were not diseased in all patients, and the non-diseased ascending aorta and aortic arch were preserved during the surgery. Replacement of the non-diseased aorta in patients with distal arch lesions remains controversial. In our institution, distal arch replacement through a median sternotomy had been performed with preservation of the healthy proximal arch and neck vessels for treatment of distal arch aneurysm. We reported the early operative results and late outcomes of this procedure, including changes in the size of the remaining arch and thoracic aorta [
10]. Twenty-three patients underwent elective distal arch replacement through a median sternotomy. The proximal end of the aneurysm was located in zone 1 in 21.7% of the patients, zone 2 in 39.1%, and zone 3 in 39.1%. With selective cerebral perfusion and hypothermic circulatory arrest, distal arch was replaced with prosthetic graft without reconstruction of the ascending aorta. Neither operative mortality nor postoperative low cardiac output syndrome occurred in all 23 patients. Two patients (8.7%) developed perioperative stroke. In the late period, two cardiovascular-related deaths occurred; one was due to rupture of the aneurysm in the descending aorta, and the other was due to heart failure. Postoperative CT showed that the maximal aortic diameter of the proximal arch increased by 0.8 ± 1.9 mm while that of the distal arch increased by 3.9 ± 9.4 mm during a postoperative follow-up period of 9.2 ± 4.7 years. These results suggest that the preserved aortic arch in mini-OSG might not influence adverse outcomes, although the number of patients was small in our previous study and careful observation is required after the surgery.
In conclusion, we performed mini-OSG with upper-half sternotomy in seven patients. This procedure might be less invasive, although further studies with large numbers of patients and intensive follow-up are needed.