J Thorac Cardiovasc Surg 2005;129:677-679
© 2005 The American Association for Thoracic Surgery
A method of using the pulmonary trunk to form a trileaflet valve
Jennifer K. White, MDa,*,
Arvind K. Agnihotri, MDa,
Christian Latrémouille, MD, PhDc,d,
Emmanuel Messas, MDb,,e,
Alain Carpentier, MD, PhDd,,f,
David F. Torchiana, MDa
a Division of Cardiac Surgery
b Department of Cardiology, Massachusetts General Hospital, Boston, Mass
c Institut d' Anatomie, UFR Biomédicale des Saints-Péres
d Department of Cardiovascular Surgery
e Cardiology, Hôpital European George Pompidou
Département de Chirurgie Cardio-vasculaire, Hôpital Broussais, Paris, France
* Address for reprints: Jennifer K. White, MD, Division of Cardiac Surgery, Massachusetts General Hospital, Bullfinch 119/50 Fruit St, Boston, MA 02114 (E-mail: jkwhite{at}partners.org).
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Dr White
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Replacement heart valves constructed from autologous tissues have been attempted, with significant variations in long-term leaflet pliability and cellular viability.1-3 A new method of creating a potentially viable trileaflet valve from autologous pulmonary artery was investigated.
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Materials and methods
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Human anatomic study
Using cadavers (n = 7), the main pulmonary trunk was removed and trimmed to create a tissue cylinder with a height equal to the corresponding aortic annulus diameter (Figure 1, A). Three longitudinal incisions, 2 mm less than one half the cylinder height, were positioned 120° apart (Figure 1, A). The resulting flaps were involuted and secured 2 to 3 mm from the superior rim of the cylinder with 6-0 polypropylene (Prolene; Ethicon, Inc, Somerville, NJ) sutures passed through adjacent flaps near their free edges and tied, making each a U stitch (Figure 1, B-D). The base of the involuted tissue was joined with additional 6-0 polypropylene sutures, creating interleaflet triangles and eliminating acute corners from the inner surface of the valve (Figure 1, E). The outermost wall was scalloped (Figure 1, D and E).
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Figure 1. Involution method of valve construction and surgical implantation. A segment of the pulmonary artery trunk was harvested and trimmed to a length (b) equal to the diameter of the corresponding aortic annulus. Three longitudinal incisions, positioned 120° apart, were created such that the length (c) of each incision was slightly less than one half the cylinder height (b; A). The resulting tissue flaps were involuted into the cylinder (B and C). Sutures were passed through adjacent flaps and secured as U stitches near the superior rim of the tissue cylinder (D). Additional U stitches secured the base of the involuted tissue to the outer cylinder, creating interleaflet triangles (E). The construct wall between the commissures was scalloped (D and E). Implantation of the valve was performed with a modified freehand technique, in which stay sutures are passed between the aortic annulus and the superior cut edge of the valve construct (F). After the construct had been lowered into the subcoronary position, a continuous 5-0 polypropylene suture was run along the superior aspect of the construct's outermost wall (G).
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Implantation was performed with a subcoronary, modified freehand method (Figure 1, F and G). After removal of the native leaflets, stay sutures were passed through the aortic annulus at a position corresponding to the midpoint of each excised leaflet. These were placed through the construct at the superior cut edge (as opposed to the base of the valve in the freehand method), and the construct was lowered into position (Figure 1, F). A 6-0 polypropylene suture was run along the superior aspect of the construct's outermost wall, following the commissural pillars' contours (Figure 1, G). Passive testing of each valve's competency was performed under a 200 mm Hg saline column, enabling endoscopic inspection of the neoleaflets. One aortic root was positioned in a flow simulator, and transvalvular pressure gradients were determined across a range of flows (1-6 L/min, 0.9% saline).
Sheep study
The valve design was tested in an adult sheep model (n = 2). Before each operation, a replacement valve derived from the pulmonary trunk of a donor sheep was passively tested. The valve constructs were implanted as aortic valve replacements in the subcoronary position by the modified freehand technique described previously (Figure 1, F and G). After weaning from cardiopulmonary bypass, the valves were examined with an epicardial echocardiography probe. Regurgitant flow was determined by continuous-wave Doppler scanning in the long-axis view. Peak velocity was obtained in the one animal in which anatomic alignment of the probe allowed measurement. All animals received humane care in compliance with the "Guide for the Care and Use of Laboratory Animals"4 prepared by the Institute of Laboratory Resources, National Research Council.
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Results
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In 5 (71%) of the 7 cadavers, there was sufficient pulmonary artery trunk tissue to construct competent aortic valve replacements by the involution method (pulmonary trunk diameter, 23.7 ± 3.3 mm; pulmonary trunk length, 24.9 ± 3.7 mm; aortic annulus diameter, 21.6 ± 2.7 mm) (Figure 2). Under passive testing, these 5 valves displayed symmetric 3-leaflet coaptation with no central orifice at closure.
The human valve construct positioned in the flow simulator had a transvalvular pressure gradient of 1 to 3 mm Hg across a range of flows 1 to 6 L/min without evidence of acute angle bending of the leaflet bases during leaflet opening. Both sheep implants demonstrated mild aortic regurgitation with symmetric and pliable leaflet mobility throughout the cardiac cycle. A peak pressure gradient of 25 mm Hg was calculated by using the modified Bernoulli equation (peak velocity of 2.49 m/s) in one animal with a 14-mm aortic annulus diameter.
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Discussion
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Previous reports have described use of the autologous pulmonary artery to create valve substitutes. The monocusp pulmonary valve replacement has been used clinically in pediatric patients undergoing Ross procedures.5 In another method, a segment of the pulmonary trunk was implanted in the subcoronary position and secured at 3 points to create a trileaflet aortic valve replacement.6 Concerns regarding surgical reproducibility and durability, particularly in the aortic position, have limited widespread clinical application.
This study describes an efficient autologous tissue valve construction method that offers several potential advantages: it might be more reproducible because construction occurs before implantation and more versatile because it can be transplanted to other implant sites. As an aortic valve replacement, it might circumvent the surgical risks and complications associated with a valve switch, in part by preserving the native pulmonary valve. Alternatively, it might offer a more suitable pulmonic valve replacement option other than a homograft or moncusp during a Ross procedure. Further investigations, including long-term animal studies, would be useful to assess the clinical feasibility of this valve construct in human patients.
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References
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- Bailey CP, Carstens HP, Zimmerman J, Hirose T. Aortic valve replacement with autogenous aortic wall. Am J Cardiol 1965;15:367-379.[Medline]
- Senning
. Alterations in valvular surgery: biologic valve. In: Cohn LH, Gallucci V, editors. Cardiac bioprostheses: proceedings of the second international symposium on cardiac bioprostheses. New York: Yorke Medical Books; 1982. pp. 140-153.
- Love JW. Biological and engineering problems of tissue heart valves. In: Love JW, editor. Autologous tissue heart valves. Austin (TX): R. G. Landes, Inc; 1993. pp. 25-31.
- Guide for the care and use of laboratory animals. Washington (DC): National Academy Press; 1996.
- Couetil JA, Berrebi A, Ferdinand FD, Fornes P, Adamopoulos C, Filsoufi F. New approach for reconstruction of the pulmonary outflow tract during the Ross procedure. Circulation 1998;98(suppl II):II368-II371.
- Hvass U. Aortic valve replacement in children using a pulmonary artery wall [in French]. Presse Med 1985;14:1926-1927.
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