Ann Thorac Surg 2007;84:1771-1773. doi:10.1016/j.athoracsur.2007.07.031
© 2007 The Society of Thoracic Surgeons
How To Do It
New Vascular Graft for Assembling the Stentless Valve Composite Graft
Paul P. Urbanski, MD*
Department of Cardiovascular Surgery, Cardiovascular Center Bad Neustadt, Bad Neustadt, Germany
Accepted for publication July 10, 2007.
* Address correspondence to Dr Urbanski, Herz-und Gefaess-Klinik, Salzburger Leite 1, Bad Neustadt, 97616, Germany (Email: p.urbanski{at}herzchirurgie.de).
| Dr Urbanski discloses that he has a financial relationship with InterVascular, Inc.
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Abstract
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The use of a new vascular tube with an uncrimped section for assembling the stentless valve composite graft is described. The graft simplifies the fixation of the valve within the tube because no stretching of the crimping is necessary to achieve optimal commissural height of the valve during sewing. Furthermore, this allows the composite construction outside the chest and reduces the cross-clamp time.
The new vascular prosthesis presented is designed for aortic root repair using different surgical techniques; for example, intraoperative assembling of the stentless valve composite graft for aortic root replacement. The prosthesis is primarily intended to facilitate the surgical procedures because technical ease determines optimal valve geometry and function and, consequently, a favorable long-lasting clinical result.
For the sewing of the stentless valve within the standard crimped tube, the bottom of the graft has to be fixed to allow the tension required to stretch the tube so that the commissures can be placed at the proper height (Fig 1). As a consequence, the suture line between the upper valve’s margin, including the commissures, cannot be performed until the anastomosis between the composite graft and the annulus is completed, thus only during cross-clamp time. In contrast, the aortic root graft described allows the complete construction of the stentless valve composite graft outside the chest because no stretching of the graft is necessary during the sewing of the valve prosthesis within the tube; and therefore, no fixation to the annulus is required.
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Fig 1. Relationship between the height of stentless valve prosthesis commissures and the (left) standard crimped tube or (right) the uncrimped tube. For this reason, during implantation of the stentless valve prosthesis within the crimped tube, constant stretching on the graft during suturing is necessary to avoid alteration of commissure height after (middle) the tube stretches out under blood pressure.
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Technique
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The aortic root graft (InterGard Woven Aortic Thoracic Graft; InterVascular, La Ciotat, France), which I designed, has been commercially available since January 2006. It is a 15-cm-long collagen-coated woven polyester tube that has a 3-cm-long uncrimped end intended for repairing the aortic root. The grafts are available in 5 even diameters ranging from 26 mm to 34 mm; however, for assembling stentless valve composite grafts, only two sizes are generally used. The crimping process of a standard tube starts with a smooth tube that is 1 mm wider than the final crimped product, which always has an even diameter—the official diameter. For this reason, the uncrimped part of the new aortic root graft is 1 mm wider than the uncrimped part; and it therefore fits better with the valve prostheses, which are only available in odd sizes.
In contrast to our previously described technique [1, 2], in which preparation of the composite graft was accomplished during cross-clamp time, the new aortic root prosthesis allows the complete conduit to be assembled outside the chest. In our series, the composite grafts were assembled generally in only two sizes. Tubes with an official diameter of 28 mm and stentless valve prostheses (SPV Toronto; St. Jude Medical Inc, St. Paul, MN) with a size of 29 mm were used for men, and 26-mm tubes and 27-mm stentless valves were chosen for women.
The xenograft was placed inside the uncrimped part of the Dacron graft (Boston Scientific Corp, Natick, MA), leaving about 3 to 5 mm of free margin of the tube below the bottom of the valve. The bottom and top circumferences of the valve prosthesis were fixed to the tube with 2 running mattress sutures, and then the graft was narrowed at the level of the sinotubular junction with 3 U stitches between the tops of the commissures (Fig 2).
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Fig 2. (A) The valve composite graft consists of a stentless valve prosthesis and the aortic root graft. The valve is fixed inside tube with 2 suture lines, and the graft is narrowed at the level of sinotubular junction with 3 U-stitches between the tops of the commissures. (B) Side view, (C) bottom view, and (D) top view.
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In this manner, prepared conduits were then sewn to the aortic annulus by passing the pledgeted interrupted mattress stitches for fixation through the annulus from the ventricular side and through the free margin of the tube from inside to outside. The use of this suture technique can compensate for significant size differences between the diameter of the tube and the annulus. As a consequence, this permits the general use of only two of the biggest valves for all patients and, therefore, significant valve oversizing in patients who have a small aortic annulus (Fig 3). The procedure was completed by distal aortic anastomosis after fenestration of the graft and implantation of the coronary buttons.
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Fig 3. Computed tomography angiography with multiplanar reconstruction after implantation of stentless valve composite graft (SPV Toronto 29 within a 28-mm aortic root graft) in a patient with aortic annulus diameter of 23 mm shows the (left) longitudinal axis as well as (middle) closing and (right) opening of the aortic valve.
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Between January 2006 and February 2007, the stentless valve composite graft described was implanted in 24 consecutive patients with aortic root disease and no repairable aortic valve defect. Although half required concomitant arch repair with circulatory arrest, the mean cross-clamp time was 90 minutes and ranged from 59 minutes for isolated aortic root replacement to 196 minutes for aortic root re-replacement because of a mechanical valve conduit endocarditis. All patients survived the surgery and have been discharged. In all cases, echocardiographic examinations before discharge and during the follow-up period of up to 1 year revealed competent valves with smooth movement of the cusps.
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Comment
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The reasons why we use the stentless valve composite graft as a standard biologic substitute for aortic root replacement have been discussed previously [2–4]. One of the most important reasons is that the placement of the stentless valve inside the tube and the supraannular technique of graft implantation allows the use of a much bigger valve than would have been possible with other biologic conduits in which the valve prostheses are situated at the end of the tube and are anastomosed directly to the annulus. This ensures the use of the full capacity of the internal orifice area of the valve prosthesis implanted for the given aortic orifice.
In contrast to conventional implantation technique, for which accurate determination of the appropriate valve prosthesis size after annular débridement is necessary, anastomosing between the annulus and a vascular graft allows general use of a tube with a diameter that differs significantly from the patient’s annulus diameter. Thus, the tube diameter rather than the annulus diameter determines the size of the valve prosthesis to be implanted. In this way, it is possible to implant stentless valves in patients with annular ectasia and an annulus diameter bigger than 30 mm or to oversize a small annulus with a considerably bigger valve prosthesis.
Because accurate measurement of the annulus to determine the valve prosthesis size is not necessary, it makes sense to assemble the composite graft outside the chest before cross-clamp time. This reduces the time of anoxic cardiac arrest, which is especially advantageous in complex surgeries. In addition, easy assembly of the stentless valve composite graft without time pressure ensures achievement of optimal geometry and function of the stentless valve, which are prerequisites for favorable long-lasting results.
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Acknowledgments
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I would like to thank Melissa Lindner and Alexandra Metz for preparing this article.
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References
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- Urbanski PP. Replacement of the ascending aorta and aortic valve with a valved stentless composite graft Ann Thorac Surg 1999;67:1501-1502.
- Urbanski PP, Hacker R. Replacement of the aortic valve and ascending aorta with a valved stentless composite graft: technical considerations and early clinical results Ann Thorac Surg 2000;70:17-20.
- Urbanski PP, Diegeler A, Siebel A, Zacher M, Hacker R. Valved stentless composite graft: clinical outcomes and hemodynamic characteristics Ann Thorac Surg 2003;75:467-471.
- Urbanski PP. Valved stentless composite graft Eur J Cardiothorac Surg 2001;20:1275-1276.
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Abstract
Introduction
