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J Thorac Cardiovasc Surg 2003;125:727-728
© 2003 The American Association for Thoracic Surgery
Brief Communications |
From the Division of Pediatric Cardiac Surgery, Lucile Packard Children's Hospital at Stanford, Stanford University School of Medicine, Stanford, Calif.
Received for publication Dec 7, 2002. Accepted for publication Aug 27, 2002. Address for reprints: Michael D. Black, MD, Pediatric Cardiac Surgery, Lucile Packard Children's Hospital, Stanford University School of Medicine, Stanford, CA 94305-5407 (E-mail: Michael.black{at}leland.stanford.edu).
Postoperative pulmonary regurgitation and stenosis still remain major determinants of long-term outcome in children requiring right ventricular outflow tract (RVOT) reconstruction.
Because of relatively low right-sided pressures, mechanical valves are at high risk for thrombosis, and long-term anticoagulation is disadvantageous in pediatric patients for obvious reasons.
1 Because of accelerated calcification, bioprosthetic valves are, on the other hand, likely to undergo structural valve deterioration in younger patients. 2
The use of a stentless valve design, with improved shear stress on the valve leaflets, might prevent early valvular calcification. The Toronto stentless porcine valve (SPV; St Jude Medical, Inc, St Paul, Minn) incorporates a flexible Dacron ring with lack of an accompanying aortic wall. We hypothesized that these distinguishing characteristics might allow for improved long-term function when used in RVOT reconstruction in children.
Clinical summary
Nine patients (8 male patients and 1 female patient) born with tetralogy of Fallot underwent RVOT reconstruction with Toronto SPVs between March 1998 and July 2001. Mean age and weight were, respectively, 11.2 years (range, 4-17 years) and 41.6 kg (range, 15.2-83.1 kg). Preoperative patient characteristics and surgical indications are summarized in Table 1. All but one procedure were reoperative, with surgical indications being RVOT stenosis (n = 4) or pulmonary insufficiency (n = 5). Intraoperative transesophageal echocardiography was performed in all patients, and transthoracic echocardiograms were obtained at various intervals after discharge. No antiaggregant or anticoagulation therapy was used. Mean follow-up was 14.5 months (range, 2-38 months).
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Comment
Pulmonary valve replacement in children still remains a difficult surgical challenge because no ideal valve substitute exists. The Toronto SPV bioprosthesis offers a better hemodynamic profile in the aortic position than stented valves, resembling the hemodynamic characteristics of an aortic homograft. At least in the aortic position, stentless valves appear to outperform stented bioprostheses, and durability beyond 10 years in a substantial number of patients is seen. 3
Most of the intermediate-term data thus far acquired on this particular bioprosthesis derives from aortic valve replacement and not RVOT reconstruction. In the pulmonary circuit, where hemodynamic stress is not as marked as in the left ventricular outflow tract, long-term durability for SPVs should be expected.
Several points should be made with regard to the technique of valve implantation (Figure 1). Orientation of the valve, with 1 anterior and 2 lateral posts, is important in avoiding obstruction of the origin of the branch pulmonary arteries. The commissural posts should ideally be spaced at 120° intervals. Because of the more modest shear stress to which the valve is subject within the RVOT, the suture line should be continuous along the entire proximal circumference of the sewing ring, rather than along the commissural posts, as usually performed while implanting SPVs in the aortic position. Lastly, should an arterioplasty be necessary, a pericardial patch can be easily incorporated into the suture line because it runs along the anterior portion of the bioprosthesis. This in turn allows for insertion of a prosthesis with optimal diameter.
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4 5 6 References
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  J. A. Hawkins, C. T. Sower, L. M. Lambert, P. C. Kouretas, P. T. Burch, A. K. Kaza, M. D. Puchalski, and A. T. Yetman Stentless porcine valves in the right ventricular outflow tract: improved durability? Eur J Cardiothorac Surg, April 1, 2009; 35(4): 600 - 605. [Abstract] [Full Text] [PDF]
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 M. D. Black, S. J. Ley, A.-M. Regal, and R. E. Shaw Novel Approach to Right Ventricular Outflow Tract Reconstruction Using a Stentless Porcine Valve Ann. Thorac. Surg., January 1, 2008; 85(1): 195 - 198. [Abstract] [Full Text] [PDF]
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J. A. Quintessenza, J. P. Jacobs, V. O. Morell, J. M. Giroud, and R. J. Boucek Initial Experience With a Bicuspid Polytetrafluoroethylene Pulmonary Valve in 41 Children and Adults: A New Option For Right Ventricular Outflow Tract Reconstruction Ann. Thorac. Surg., March 1, 2005; 79(3): 924 - 931. [Abstract] [Full Text] [PDF]
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