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Ann Thorac Surg 1999;68:2383-2384
© 1999 The Society of Thoracic Surgeons
a Divisione di Cardiochirurgia, Ospedale Silvestrini, 06100 Perugia, Italy
To the Editor
I read with interest the paper by Urbanski [1]. Despite the lack of the systolic property of the aortic root using a stentless valve inserted in a rigid Dacron tube, I nevertheless agree with the opportunity to use a stentless valve in selected cases requiring a Bentall-like operation. I also performed some button-Bentall operations using a Toronto SPV bioprosthesis (St. Jude Medical, St. Paul, MN), assembled during aortic clamping period with a collagen-coated woven Dacron vascular tube (Intervascular, La Ciotat, France) for combined replacement of aortic valve, root, and ascending aorta. The advantage of choosing the stentless bioprosthesis are: (1) to have a larger orifice valve in comparison to a stented bioprosthesis for the same aortic annulus; (2) to reduce the likelihood of thromboembolism and probably prosthetic endocarditis due to the laminar blood flow through the Toronto SPV valve; and (3) possibly to prolong the durability of the bioprosthesis, reducing the commissural stress in comparison with a stented bioprosthesis.
I use a slightly different technique of implantation of the Toronto SPV bioprosthesis inside the Dacron tube, in comparison with that presented in the above article [1]. The vascular tube is everted at one end leaving a rim of 5 to 7 mm. Then I first secure the Toronto SPV inside the tube, putting three single stitches to the edge at three equidistant points of the inferior suture line (the annular suture), corresponding at the three equidistant transversal color stitches of the Toronto SPV, to avoid any distortion. After sewing the bioprosthetic valve and the tube together to the native aortic annulus, as Urbanski does, the rim of the Dacron tube is inverted and sewn to a corresponding short rim of aortic root, left during dissection of the aortic root and coronary buttons. This continuous suture is useful in improving hemostasis of a weak suture line, and for better securing the Dacron tube when redo operation become necessary because of valve failure. This only takes a few more minutes, and then the posts are fixed inside the vascular tube, taking care to avoid any distortion of the Toronto SPV valve, and the sinus of Valsalva suture is complete.
There is one topic on which I do not agree with Dr Urbanski. I think there is no reason to choose a Dacron tube with a smaller diameter than that of the bioprosthesis. The external shape of the Toronto SPV bioprosthesis is cylindrical and so the valve can be inserted into a cylinder. By reducing the annular diameter of the bioprosthesis, and by insertion in a smaller size tube, we can cause some degree of distortion to the cusps. Furthermore, increasing the surface of coaptation of the cusps causes major stress on these surfaces, and probably cause predisposition to earlier calcification. I always use a 1-mm larger Dacron tube in respect to the Toronto SPV, and at postoperative color Doppler echocardiography, both transthoracic and transesophageal, bioprosthesis incompetence was not revealed. Since usually some degree of distal ascending aorta dilation is common when Bentall operation is scheduled, employing a larger size Dacron tube yields a reduction in the chance of mismatch between the aorta and vascular prosthesis, extending the indications of this surgical technique.
In conclusion, this technique is an attractive alternative in selected cases, with optimal results, but should be performed by experienced surgeons.
References
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