Ann Thorac Surg 2002;74:2202-2205
© 2002 The Society of Thoracic Surgeons
How to do it
Polytetrafluoroethylene monocusp valve technique for right ventricular outflow tract reconstruction
Mark W. Turrentine, MDa*,
Ryan P. McCarthy, BSa,
Palaniswamy Vijay, PhDa,
Andrew C. Fiore, MDb,
John W. Brown, MDa
a Department of Surgery, Division of Cardiothoracic Surgery, Indiana University School of Medicine, Indianapolis, Indiana,, USA
b Department of Surgery, St. Louis University School of Medicine, St. Louis, Missouri, USA
Accepted for publication June 5, 2002.
* Address reprint requests to Dr Turrentine, Department of Surgery, Division of Cardiothoracic Surgery, Indiana University School of Medicine, 545 Barnhill Dr, Emerson Hall #215, Indianapolis, IN 46202, USA.
e-mail: mturren{at}iupui.edu
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Abstract
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Nonvalve transannular patch repair of right ventricular outflow tract obstructive (RVOTO) defects results in pulmonary insufficiency, which can contribute to early postoperative right ventricular dysfunction. In both animal and clinical studies, monocusp valves provide perioperative RVOT competence and improved right ventricular functional characteristics. In these reports, monocusp leaflet construction with 0.1-mm polytetrafluoroethylene (PTFE) appeared equal, or superior, to biologic monocusp valves. Construction of the polytetrafluoroethylene monocusp valve is an inexpensive and straightforward way to create a competent RVOT in a variety of RVOTO anomalies. Based on our clinical experience, it effectively prevents short-term and significantly reduces midterm pulmonary insufficiency without evidence of stenosis.
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Introduction
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The surgical management of right ventricular outflow tract obstruction (RVOTO) in congenital cardiac defects remains controversial and options can differentially influence both the short- and long-term fate of the right ventricle (RV). Historically, repairs included either transannular patch or valve conduit insertion with both having their respective short- and long-term disadvantages [1–3]. In patients with RV-pulmonary artery (PA) continuity, nonvalve transannular repairs remain favored by many surgeons, but there is increasing evidence that creation of a monocusp outflow patch has short-term clinical and potentially midterm RV remodeling advantages in patients in whom pulmonary valve sparing techniques are not feasible [4]. A variety of monocusp materials have been evaluated with variable clinical and functional results [5, 6]. Our animal studies concluded that functional and durability characteristics favored monocusp valves created with 0.1-mm polytetrafluorethylene (PTFE) [7]. Based on an experience with over 150 implants in humans, this article reviews technical considerations in the construction of PTFE monocusp valves [4].
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Technique
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Following a vertical insertion in the main pulmonary artery, the pulmonary valve and annulus are inspected (Fig 1A).
When possible, an aggressive pulmonary valvotomy is performed and the annulus measured with a Hegar dilator. In patients with moderate-to-severe hypoplasia of the annulus (generally more than 1 mm smaller than a -1 Z-value) or if the post-repair RVOT gradient measures greater than 25 to 30 mm Hg, a transannular repair is generally performed [4]. The anterior pulmonary leaflet and pulmonary annulus are incised leaving a functional posterior leaflet. The ventriculotomy is carried onto the RV only as far as necessary to alleviate the infundibular narrowing. The incision in general is limited to approximately 1 cm or, in patients with a long, narrowed infundibulum and conal septum, it may be carried slightly further (Fig 1B). Consideration regarding the length of the infundibulotomy is also paid to whether a transatrial or transventricular repair of the ventricular septal defect is selected. In either case, the ventricular incision does not extend beyond the edge of the conal septum. At the midpoint of the incision, the edges of the ventriculotomy are retracted with horizontal mattress pledgetted stay sutures. The VSD is closed, avoiding excessive pledget material along the conal septum. If an interrupted suture technique is utilized, we favor 5-0 Ticron sutures (US Surgical Corp, Norwalk, CT) with thin, soft pledgets, which are low profile and easily endothelialized. Then, 5-0 polypropylene stay sutures are placed at the level of the anticipated hinge point, or cephalad extension of the monocusp valve (Fig 1B). Exposure of the "floor" of the RVOT in this manner allows the described technique to maximize the outflow diameter. A bullet-shaped piece of 0.1-mm PTFE is fashioned by placing the material in the ventricular portion of the opening and allowing it to lay flush along the ventricular walls and conal septum, thereby maximizing surface area coaptation. The edges of the PTFE are traced with a marking pen according to their point of contact with epicardial surface, and the material is cut to the dimensions as outlined by the mark. This complements the RVOT anatomic geometry, but without excess material (Fig 1C). The monocusp is sutured beginning at the proposed hinge point and extending onto the epicardial surface of the ventricle using 6-0 PTFE suture with bites including at least one-half the depth of myocardium (Fig 1D). Care is taken to ensure the superior edge of the monocusp matches that of the retained posterior leaflet (Fig 1E). Competence of the monocusp valve occurs as a result of its coaptation with the remnant leaflet tissue and outflow septum (Fig 2).
The outflow patch, or hood, is constructed using a 0.4-mm PTFE cardiovascular patch in an elongated teardrop configuration (Fig 1F). Suturing to the monocusp valve requires sutures not be placed deeper than the existing suture line so as to avoid narrowing the open diameter of the reconstructed outflow tract.
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Fig 2. Intraoperative transesophageal echocardiography demonstrating polytetrafluoroethylene monocusp leaflet (arrow) coaptation with retained posterior pulmonary valve leaflet.
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Following a standard redo sternotomy and institution of cardiopulmonary bypass with bicaval cannulation, the previous RV-PA conduit is opened longitudinally and, when necessary, the incision extended across the proximal and distal suture lines (Fig 1G). This is particularly important for degenerative homograft conduits because of the propensity for suture line stenosis in these locations. The redundant edges of the old conduit are trimmed laterally and retracted with stay sutures. The monocusp valve is constructed starting in the mid-portion of the old conduit. It is then covered with a PTFE (0.4 mm) cardiovascular patch. With Dacron (C.R. Bard, Lowell, MA) conduits, the material can be entirely removed and the remaining posterior fibrous peel becomes the back wall of the RVOT maintaining RV-PA continuity. The monocusp is sewn to the edges of the outflow tract and, as before, the entire RVOT covered with a PTFE (0.4 mm) cardiovascular patch, in a manner similar to that described by Danielson and colleagues for nonvalved conduit replacement [8]. Sizing of the monocusp is essentially the same as with other repairs; the material must have adequate length and width in order to have sufficient surface area contact against the posterior wall.
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Comment
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Previous reports in the literature are inconclusive regarding perioperative function and clinical benefit of monocusp RVOT reconstruction. These variable results may reflect the challenges of free-hand construction and certainly are influenced by the material used in valve construction. However, in our hands, construction of the PTFE monocusp valve has proven to be a simple and reproducible technique demonstrating excellent early postoperative function with minimal pulmonary insufficiency. Interestingly, in some patients, the PTFE monocusp valve has been found to retain a moderate degree of competency at midterm follow up [4]. Regardless, growth of the RVOT and fibrocollagenous incorporation of the leaflets will negatively impact midterm function resulting in progressive pulmonary insufficiency but not stenosis. The PTFE monocusp should not be considered anything but a short to midterm functional valve.
Our clinical findings suggest a degree of benefit over transannular patch repairs, particularly in patients with either tetralogy of Fallot or ventricular septal defect with pulmonary atresia [4]. As a result, we favor its use in those groups of patients. Individuals with other types of complex RVOTO lesions might be better served with an alternative technique [4]. In patients undergoing complete repair with defects demonstrating absence of the conal septum or morphologically distorted RVOT (ie, tetralogy of Fallot or absent pulmonary valve), significant peripheral pulmonary stenosis, or severe pulmonary hypertension, use of a biologic valve (or conduit), is the procedure of choice.
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References
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- Kirklin J.K., Kirklin J.W., Blackstone E.H., Milano A., Pacifico A.D. Effect of transannular patching on outcome after repair of tetralogy of Fallot. Ann Thorac Surg 1989;48:783-791.[Abstract]
- Ellison R.G., Brown W.J., Jr, Yeh T.J., et al. Surgical significance of acute and chronic pulmonary valvular insufficiency. J Thorac Cardiovasc Surg 1970;60:549-558.[Medline]
- Kirklin J.W., Blackstone E.H., Jonas R.A., et al. Morphologic and surgical determinants of outcome events after repair of tetralogy of Fallot and pulmonary stenosis: a two-institution study. J Thorac Cardiovasc Surg 1992;103:706-723.[Abstract]
- Turrentine M.W., McCarthy R.P., Vijay P., McConnell K.W., Brown J.W. PTFE monocusp valve reconstruction of the right ventricular outflow tract. Ann Thorac Surg 2002;73:871-880.[Abstract/Free Full Text]
- Gundry S.R. Pericardial and synthetic monocusp valves: indication and results. Semin Thorac Cardiovasc Surg 1999;2:77-82.
- Bigras J.-L., Boutin C., McCrindle B.W., Rebeyka I.M. Short-term effect of monocuspid valves on pulmonary insufficiency and clinical outcome after surgical repair of tetralogy of Fallot. J Thorac Cardiovasc Surg 1996;112:33-37.[Abstract/Free Full Text]
- Scavo V.A., Turrentine M.W., Aufiero T.X., et al. Monocusp valve and transannular patch reconstruction of the right ventricular outflow tract: an experimental study. ASAIO J 1998;44:M480-485.[Medline]
- Danielson G.K., Downing T.P., Schaff H.V., Puga F.J., DiDonato R.M., Ritter D.G. Replacement of obstructed extracardiac conduits with autogenous tissue reconstructions. J Thorac Cardiovasc Surg 1987;93:555-559.[Abstract]
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Abstract
Introduction
