DISCUSSION
Surgical repair of aneurysms and aortic dissections involving the aortic arch is still challenging, carrying high mortality and morbidity. Our experience with the first 70 consecutive patients treated with FET using Thoraflex Hybrid has been overall satisfactory; technical success was achieved in all patients even in the first part of our experience, started after performing only conventional elephant trunk (ET) or conventional surgery in acute dissection (ascending aorta or hemiarch replacement). Our results show that the implantation technique for Thoraflex Hybrid graft is doable and reproducible, also in acute setting.
Correct cerebral perfusion during hypothermic circulatory arrest is one of the main factors determining neurological outcomes.7–9 Our strategy allows a uniform cerebral perfusion throughout the operation, except for the short time needed for LCA and LSA anastomosis, thus minimizing cerebral ischemia time. We believe that this technical aspect is important to explain our particularly good results in terms of neurological complications, with a significantly lower overall incidence of permanent stroke (1.4%) compared to data from similar studies.7 Shresta et al. reported 8% of major CVA in their first experience in performing a FET with the Thoraflex with a different brain protection strategy, while Chu et al. reported a 5% stroke incidence.10,11 In addition to our cerebral perfusion strategy, we believe that our technique, avoiding direct cannulation and manipulation of cerebral vessels, could reduce the embolism rate thus helping to minimize CVA complications.
Another interesting finding from our study is the very low rate of spinal cord injury which occurred in only one patient (1.4%) operated for acute aortic dissection. We believe that our good results are due to the use of a combination of 100 mm stented length (less intercostal arteries coverage), Thoraflex Hybrid deployment in zone 2, short circulatory arrest time and correct sizing of the stented graft.12 Fiorentino et al reported a low overall incidence of SCI (two cases of temporary isolated papaparesis) but only in 150 mm distal stented grafts.13 Flores et al reported a very high incidence of SCI in FET when the stented was deployed at the lower level of the thoracic aorta.14
It has been reported that in Thoraflex implant the LSA anastomosis remains the Achilles heel being too close to the collar device.11 We overcome this problem by extending the surgical incision with a small left supra-clavicular cervicotomy and “elongating” the LSA with a tubular prosthesis, thus making the anastomosis technically easier and achieving success in all cases. In one case, not included in this series, we successfully used a custom-made Thoraflex Hybrid, in which the plexus is separated from the main part of the prosthesis, in order to make anastomosis easier, improve operating times and correctly position the intra-thoracic vessels.15
Overall survival for the entire cohort at 30 days was 90% (95% CI, 83.2—97.3), without statistically significant differences between emergency and elective surgery (87.9% vs. in emergency vs. 93.2% in chronic settings, P=0.312).
We believe that our results should contribute to encourage employing this surgical strategy, especially in emergency setting where the FET may be helpful particularly in patients with malperfusion and could result in a definitive treatment. The idea of specialized centers with a high volume of aortic surgery to treat both chronic and acute aortic syndrome is now becoming paramount. There is a large consensus that patients affected by acute aortic syndromes may benefit from treatment at dedicated specialized aortic centers with significantly improved outcomes and decreased mortality. Patients undergoing emergency repair of acute aortic dissection by lower-volume surgeons and centers have approximately double the risk-adjusted mortality of patients undergoing repair by the highest volume care providers.16 We think that the future treatment of acute type A aortic dissection is going toward a total arch approach with standardized cerebral protection that should more and more be delivered by specialist aortic centers with expertise in this technique. In this case the Thoraflex Hybrid proved to be an easy-to-implant prosthesis, making the brain protection strategy easier and reporting a low complication rate.
Finally, an important aspect of our study is the relatively large number of cases done in a short period of time in a single institution, thus allowing for a significant reduction of multicenter studies bias. Other series available in literature report results of a similar cohort of patients but operated in different centers: the Canadian experience enrolled 40 consecutive cases in 9 different centers, in about 3 years of activity while the English experience counts 66 cases in 4 years from 9 centers throughout UK.17