Does It Matter? Commentary on Prosthetic Graft Dilation at the Aortic Arch in the Era of Hybrid Aortic Surgery

摘要

In this issue of The Annals of Vascular Diseases, Hori and colleagues from Saitama are to be congratulated for their insightful and yet puzzling report regarding dilatation of the thoracic vascular graft after arch replacement. They found that risk factors for late dilatation of the thoracic graft were as follows: age at operation, knitted-type prosthesis, and prevalence of cerebral vascular disease. They concluded that prosthetic graft selection and appropriate sizing of the stent graft should be considered for each hybrid aortic surgery to maintain oversizing of the stent graft. It is well-known that the knitted thoracic Dacron graft dilates more than the woven one. The Gelseal knitted graft has reported a dilatation of 30% of the diameter several years after implantation, whereas the other woven ones have a dilation of <15%. The Triplex graft, made of two knitted graft layers, is combined with the middle elastomeric membrane. The outer “double Raschel pattern” knitted layer is already stretched by 40% during the manufacturing process. The inner layer is “double Raschel pattern” knitted and not stretched. Although the Triplex graft is rigid, the results of this paper seem to be understandable. However, the dilatation ratio of the Triplex graft was small, 1.18 at 40 months. Even the native aorta grows greater than this. The post-market survey of the Triplex graft conducted by the Terumo company reported a dilatation ratio of 1.10±0.15 at 7 years in 696 patients. In in-vitro pulsatile test (400,000,000 beat, 25 Hz) of three Triplex graft materials, the dilatation ratio was 1.07±0.025. In addition, the authors stated that the diameter at the distal anastomosis of the Triplex graft was rather stable (there was no description in the text when the measurement was performed). As the authors stated, there are some limitations of this paper. Of course, the number of patients was too small to draw meaningful conclusions, but in the panels of Hemashield graft or J graft in Fig. 1, a few grafts showed considerable dilation.