Ann Thorac Surg 2006;82:1128-1130
© 2006 The Society of Thoracic Surgeons
How to do it
Implantation of a Modified Freestyle Valve With a Single Inflow Suture Line: Technical Patterns and Advantages
Daniel Grandmougin, MDa,*,
Georges Fayad, MDb
a Department of Cardiovascular Surgery, Hôpital Nord-CHU, Saint-Etienne, France
b Department of Cardiovascular Surgery, Hôpital Cardiologique-CHU, Lille, France
Accepted for publication August 29, 2005.
* Address correspondence to Dr Grandmougin, Service de Chirurgie Cardiovasculaire, Hôpital Nord-CHU, Saint-Etienne, 42 055 Cedex 02 France (Email: d.grandmougin{at}tiscali.fr).
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Abstract
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Subcoronary implantation of stentless valves may be a surgical challenge in the small aortic root. In addition, calcifications of coronary ostia may interfere with the procedure. We present a technique to trim a Freestyle stentlesss root (Medtronic Inc, Minneapolis, MN) and facilitate implantation with a single inflow suture line.
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Introduction
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Surgical treatment of aortic valve disease improves life expectancy. However, severity of left ventricular hypertrophy remains an important determinant of survival after surgery [1] because it provides a threefold greater risk of mortality in patients independently from coronary artery disease [2]. Persistent left ventricular hypertrophy mainly results from a significant transvalvular gradient with a patient–prosthesis mismatch. Mismatch is moderate when the indexed effective orifice area is less than 0.85 cm2/m2 and it is severe when the indexed effective orifice area is less than 0.65 cm2/m2 [3]. Therefore, hazard of mismatch increases with both the incidence of small aortic annulus and the stenotic effects of contemporary valvular prostheses [4].
In an effort to elude mismatch and relieve left ventricular burden, surgeons may enlarge the annulus, implant prosthesis with an optimized geometry, or replace the aortic root. In view of optimal left ventricular hypertrophy regression and clinical outcome, there is a resurgence of evidence supporting the use of stentless bioprosthesis mainly in patients with small aortic roots and poor left ventricular function. However the greatest drawback to the use of stentless valves seems to be the technical challenge of implantation with various techniques often associated with prolonged cross-clamp times and potential for perivalvular leakage. Therefore in order to simplify implantation in patients with a small annulus, we describe an original technique to trim the Freestyle stentlesss root (Medtronic Inc, Minneapolis, MN) and perform implantation with a single inflow suture line (ie, stented-like implantation).
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Technique
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Using standard cardioplegic arrest, aorta is partially transected in a horizontal fashion 1.5 to 2 cm above the right coronary artery to stay above the sinotubular junction. The aortic valve is excised and the annulus is debrided of calcareous deposits. Removal of calcifications surrounding the coronary ostia is not mandatory.
Both the annulus and sinotubular junctions are accurately sized with the adequate sizer fitted to the plane of implantation. Then the trimming step of the Freestyle bioprosthesis (Medtronic Inc) is considered. The vascular wall is entirely removed right to the polyester covering at which its integrity is cautiously preserved. Three rectangular commissural tabs of the vascular wall are spared for their attachment (Fig 1).
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Fig 1. Views of the Freestyle root (Medtronic Inc, Minneapolis, MN) before and after removal of the vascular wall. Only three patches (numbered 1, 2, and 3) of the aortic wall are preserved for commissural attachment.
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The implantation technique is similar to a stented bioprosthesis. The inflow suture line of the stentless valve, which is delineated by the green demarcation line, is fixed to the native annulus with 2-0 braided polyester sutures, and each commissural post of the prosthesis is attached to the aorta in the vicinity of the sinotubular junction by three 4-0 polypropylene "U" stitches. The superior stitch (above the commissure) is horizontal, whereas both inferior stitches (below the commissure) are vertical (Fig 2). The aortotomy is then closed according to the surgeon's habit.
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Fig 2. Final aspect after implantation. The modified Freestyle valve (Medtronic Inc, Minneapolis, MN) is fixed with one single inflow suture line, and each commisssure is attached to the patient's aortic wall with three polypropylene 4-0 stitches (1 horizontal and 2 vertical).
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Four patients underwent aortic valve replacement with Freestyle valves (Medtronic Inc) according to the present technique. All patients had narrow aortic roots (ie, 17 mm, 19 mm, 19 mm, and 19 mm) with an identified risk of patient–prosthesis mismatch (mean indexed effective orifice area, 0.81 cm2/m2). Mean age was 73.4 years (range, 62 to 79 years). In all cases, the modified Freestyle bioprosthesis (Medtronic Inc) could be implanted (ie, 21 mm, 21 mm, 21 mm, and 23 mm). Mean postoperative gradient and indexed effective orifice area were respectively 12 ± 6 mm Hg and 1.36 cm2/m2. During the 18 to 52 month observation period, no valvular incompetence was reported.
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Comment
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Aortic bioprosthetic valves are currently used in patients older than 65 years or in younger patients for whom oral anticoagulants are contraindicated. This latter feature emphasizes an important evolution because the patient's quality of life is considered independently of valve-related or anticoagulant-related events. Consequently, rate of implantation of biological valves regularly increased. More recently, due to superior hemodynamic performance, encouraging clinical outcomes [5, 6] and possibilities to overcome specific problems associated with stented valves, the stentless xenografts seemed to be the optimal valvular substitutes.
However, initial enthusiasm partly decreased because controversies still existed regarding the real advantages of stentless valves [4–7] in comparison with their stented counterparts and the increasing hazard for structural valve deterioration in late follow-up [6].
In addition, narrow aortic annulus or calcified coronary ostia increased the difficulty of the procedure. Consequently, surgeons may enlarge annulus, use a full-root technique with longer ischemic times and increased operative risks [8], or implant small-sized stented prosthesis and hamper left ventricular mass regression.
Therefore a major question still remains to be debated: is the stentless concept suitable for all cases independently of anatomic conditions?
This technical report simplifies implantation because a stented-like procedure is available with a single interrupted inflow suture line and three commissural mattress sutures. Consequently, neither small annulus nor calcifications of coronary ostia interfere with implantation.
This new design of the Freestyle valve (Medtronic Inc) is characterized by the suppression of the vascular supporting wall. This modification may decrease transprosthetic gradients in two ways. In one way the obstructive component of the aortic wall within the native aortic root is dramatically reduced [8]. In the other way removal of the vascular wall eliminates potential for any obstructive hematoma formation between the outer wall of the prosthesis in the native aortic sinus and leads to immediate optimal gradients. Furthermore, excision of the vascular wall increases pliability of the valve facilitating its manipulation, which is particularly relevant in a small aortic root.
Recently a new equine pericardial prosthetic valve [9] was designed that allows commissural suspension and the avoidance of a running suture to attach the rims of the valve to the native aorta at the outflow side of the prosthesis. This concept of replacing only the aortic leaflets is comparable with our modified Freestyle valve (Medtronic Inc) and was developed to gain advantages of only needing one suture line at the inflow side, saving time and making the implantation easier. Short-term results are encouraging [9], and similar to our experience these results have demonstrated that this new valvular geometry has no pejorative effect on the performance of the valve. Nevertheless, in opposition to porcine stentless valves, long-term outcome of equine pericardial tissue remains uncertain, namely degeneration and durability. Consequently, further data documenting long-term performance and additional experience will be necessary to assess the late success of this new valve.
In conclusion, owing to the new design of the Freestyle valve (Medtronic Inc), implantation is facilitated both in usual or unfavourable anatomic conditions with no deterioration of valvular performances.
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Acknowledgments
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The authors thank Anne Augier and François Georgelin for their assistance with this article.
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References
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Abstract
Introduction
