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Asian Cardiovasc Thorac Ann 2002;10:369-371
© 2002 Asia Publishing EXchange Pte Ltd

HOW TO DO IT

Freestyle Xenograft Implantation Technique for Reducing Aortic Insufficiency

Ahmed A Arifi, MD, Wan Song, MD, Samer Nashef, MD, Calvin SH Ng, MBBS, Innes YP Wan, MD, Anthony PC Yim, MD

Division of Cardiothoracic Surgery Department of Surgery The Chinese University of Hong Kong Prince of Wales Hospital Shatin, New Territories, Hong Kong People’s Republic of China
For reprint information contact: Ahmed A Arifi, MD Tel: 852 2632 2629 Fax: 852 2637 7974 email: arifiahmed{at}hotmail.com Division of Cardiothoracic Surgery, Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong, People’s Republic of China.

   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 TECHNIQUE
 DISCUSSION
 REFERENCES
 
The Freestyle aortic xenograft has been shown to be safe and effective for aortic valve replacement. However,implantation is often complicated by aortic valve insufficiency, which could lead to premature valve failure. We describe an implantation technique that can potentially prevent aortic insufficiency.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
TECHNIQUE
 DISCUSSION
 REFERENCES
 
The Freestyle aortic xenograft is a well-accepted alternative for replacing the diseased aortic valve, and its superior hemodynamic performance over mechanical prostheses has been proven.1,2 A degree of aortic insufficiency remains a frequent finding following implantation, with a reported incidence between 20% and 30%.1,3,4 The development of aortic insufficiency has been attributed to floppy leaflets, caused by size mismatch between the prosthesis and the native annulus, or to hematoma between the native aorta and the wall of the prosthesis when the "cylinder-within-cylinder" technique is used.5,6 Although usually mild, aortic insufficiency can result in premature valve failure because of either mechanical stress or endocarditis.

In the commonly used cylinder-within-cylinder technique described by Westaby,7 the inflow sutures do not include the interleaflet triangles and the space between the native and the graft aortic layers at the noncoronary sinus is not closed. Preserving the interleaflet triangles and closing the space between the aortic layers may prevent the development of aortic insufficiency. This study sought to monitor aortic valve performance after implantation using the following technique.


   TECHNIQUE
TOP
 ABSTRACT
 INTRODUCTION
 TECHNIQUE
DISCUSSION
 REFERENCES
 
Three simple interrupted sutures of 2/0 Ethibond are inserted at the base of each interleaflet triangle (Figure 1Go), and 7 single interrupted sutures are inserted along the nadir of each coronary cusp. The Freestyle valve (Medtronic, Inc., Minneapolis, MN, USA) is oriented by aligning the porcine coronaries with the patient’s coronary ostia. With the valve held above the commissure between the coronaries using atraumatic forceps, the valve sutures are inserted through the inflow cloth of the xenograft, starting at the interleaflet triangle between the right coronary and the noncoronary cusps. After the valve is lowered into place, the sutures are tied and cut.



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  		Figure 1. The inflow suture line showing the 3 sutures at the base of the interleaflet triangles.

 
The ligated porcine coronaries are tailored to match identically the corresponding coronary ostia while leaving the porcine noncoronary sinus intact. The porcine aorta is then trimmed to the length of the native semi-transected aorta. The outflow layer is sutured in place using double-armed 4/0 polypropylene on a 16-mm needle. The suture line runs from the commissure between the right and the left coronary sinuses, skirting around the right coronary ostium, to the commissure between the right coronary and the noncoronary sinuses, and then along the noncoronary sinus joining the 2 aortic layers. The left arm of the suture continues towards and skirts around the left coronary ostium. The 2 arms are tied at the commissure between the left coronary and the noncoronary sinuses. Three interrupted horizontal mattress sutures of 4/0 polypropylene are inserted at the center of the noncoronary sinus of the porcine and the native aortae to close the potential space between the 2 aortic layers and to reinforce the noncoronary sinus (Figure 2Go). The aortotomy is then closed using continuous 4/0 polypropylene.



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  		Figure 2. The outflow suture line showing the suture binding the porcine noncoronary sinus to the native aorta.

 
This technique has been used in 10 patients (6 males) with a mean age of 71 years (range, 61 to 81 years). The valve pathology was aortic stenosis in 7 patients and aortic regurgitation in the remaining 3. The mean size of the valves implanted was 23 mm. Transthoracic echocardiography was performed at the time of hospital discharge, at 6 months, and annually thereafter. After a mean follow-up period of 9 months (range, 6 to 15 months), there was no evidence of aortic insufficiency in any patients using this technique.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 TECHNIQUE
 DISCUSSION
REFERENCES
 
The aortic root is made up of the aortic sinuses, the valve leaflets, and the interleaflet triangles. These sinuses can be considered the basic structural unit of the aortic valve. They support the coronary arteries and the valve leaflets and, by allowing formation of the vertices, enable complete valve closure. Each pair of sinuses is separated at their base by an interleaflet triangle, which is the area bounded by the semilunar attachments of the leaflets. The interleaflet triangles are crucial for proper valve function.6 The aortic sinuses function independently of each other, but there are important functional interrelationships and dynamism between them, the valve leaflets, and the supporting left ventricular structures that produce the 3 fibrous interleaflet triangles.8 Therefore, the competence of the Freestyle valve depends on the supportive function of the native aortic sinuses. This view is reinforced by the very low incidence of aortic insufficiency if the Freestyle valve is used as a total aortic root replacement.4

We hypothesize that incorporating the interleaflet triangles in the inflow suture line preserves the function of the native aortic sinuses and that obliterating the space between the untrimmed noncoronary sinus and the native aorta reinforces the function of the implanted noncoronary sinus, thus preventing its prolapse during valve closure. Our initial experience with this technique is encouraging, but further studies are required to determine if it prevents aortic insufficiency and valve failure in the long term.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 TECHNIQUE
 DISCUSSION
 REFERENCES
 

  1. Westaby S, Jin XY, Katsumata T, Arifi A, Braidley P. Valve replacement with a stentless bioprosthesis: versatility of the porcine aortic root. J Thorac Cardiovasc Surg 1998;116:477–81.[Abstract/Free Full Text]

  2. Arifi AA, Wan S, Yim AP. Aortic valve incompetence after implantation of Freestyle stentless bioprosthesis: a technical issue? J Thorac Cardiovasc Surg 2001;121:599–601.[Free Full Text]

  3. Casabona R, De Paulis R, Zattera GF, di Summa M, Bottone W, Stacchino C, et al. Stentless porcine and pericardial valve in aortic position. Ann Thorac Surg 1992;54:681–5.[Abstract]

  4. Nguyen Van-Cao A. Echocardiography and the aortic stentless valves. In: Piwnica A, Westaby S, editors. Stentless bioprostheses. Oxford: Isis Medical, 1995.

  5. Doty DB, Cafferty A, Kon ND, Huysmans HA, Krause AH Jr, Westaby S. Medtronic Freestyle aortic root bioprosthesis: implant techniques. J Card Surg 1998;13:369–75.[Medline]

  6. Sutton JP III, Ho SY, Anderson RH. The forgotten interleaflet triangles: a review of the surgical anatomy of the aortic valve. Ann Thorac Surg 1995;59:419–27.[Abstract/Free Full Text]

  7. Westaby S. Cylinder within a cylinder method for porcine aortic root implantation. In: Piwnica A, Westaby S, editors. Stentless bioprostheses. Oxford: Isis Medical, 1995.

  8. Yacoub MH, Kilner PJ, Birks EJ, Misfeld M. The aortic outflow and root: a tale of dynamism and crosstalk. Ann Thorac Surg 1999;68:37–43.





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