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Ann Thorac Surg 2005;79:924-931
© 2005 The Society of Thoracic Surgeons
a The Congenital Heart Institute of Florida (CHIF), All Children's Hospital and Children's Hospital of Tampa, University of South Florida, St. Petersburg and Tampa, Florida, United States
Accepted for publication May 7, 2004.
* Address reprint requests to Dr Quintessenza, The Congenital Heart Institute of Florida (CHIF), University of South Florida School of Medicine, Cardiac Surgical Associates, 603 Seventh St S, Suite 450, St. Petersburg, FL 33701, USA
jaqmd{at}hotmail.com
Presented at the Poster Session of the Fortieth Annual Meeting of The Society of Thoracic Surgeons, San Antonio, TX, Jan 26–28, 2004.
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Abstract |
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METHODS: A bicuspid pulmonary valve with orifice size greater than 24 mm is created with polytetrafluoroethylene and sutured into the right ventricular outflow tract. To obviate the need for reoperation in growing children, this technique is limited to older children and adults. Polytetrafluoroethylene bicuspid pulmonary valves were placed in 41 patients (age: range, 5.0 to 64.7 years, median = 15.7 years; weight: range, 14.2 to 99.0 kilograms, median, 52.0 kg). All patients had pulmonary insufficiency, pulmonary stenosis, or both, after previous intervention for tetralogy of Fallot (27), pulmonary stenosis (11), pulmonary atresia with intact ventricular septum (2), or double outlet right ventricle (1).
RESULTS: All patients left the operating theater with transesophageal echocardiography documenting no pulmonic stenosis and zero to trace pulmonic insufficiency. Median hospital length of stay was 5 days (range, 3 to 15 days; mean, 5.8 days). Follow-up including echocardiography ranged from 0.2 to 3.1 year (median follow-up, 1.5 years) and revealed significant improvement in New York Heart Association Classification, pulmonary insufficiency, and right ventricular end diastolic dimension.
CONCLUSIONS: Polytetrafluoroethylene bicuspid pulmonary valve reconstruction of the right ventricular outflow tract is a safe, effective, and durable technique for the short term. Appropriate oversizing minimizes outflow tract obstruction while maximizing competence. Long-term follow-up is necessary to determine the true value of this technique.
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Introduction |
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| Dr Jacobs discloses that he has a financial relationship with CardioAccess, Inc.
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| This article has been selected for the open discussion forum on the CTSNet Web site: http://www.ctsnet.org.discuss
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Many patients present in need of reoperative surgical reconstruction of the right ventricular outflow tract (RVOT). Typically there is a history of previously operated tetralogy of Fallot (TOF) or pulmonary stenosis (PS). The predominant physiologic lesion is pulmonary insufficiency (PI), but varying degrees of RVOT obstruction may also be present. It is generally believed that patients tolerate PI reasonably well; however, in some, the long-term effects of PI and subsequent RV dilatation and dysfunction are associated with poor exercise tolerance and increased incidence of arrhythmias and sudden death [1, 2]. Numerous studies support pulmonary valve replacement as treatment for PI in order to improve performance status, optimize hemodynamics, and better control arrhythmias [3–10]. Multiple surgical options for pulmonary valve replacement are available for these patients including aortic and pulmonary homografts, stented and stentless porcine valves, porcine valve conduits, bovine jugular vein conduits, and even mechanical valves and mechanical valve conduits [11–32]. The optimal timing for and the specific valve used for RVOT reconstruction remain uncertain.
As the population of children with repaired congenital heart disease ages, an increasing number of patients will benefit from pulmonary valve insertion. Less than ideal experience with currently available options for pulmonary valve replacement and RVOT reconstruction [11–32] stimulated our interest into employing alternative materials and techniques. Favorable experimental and clinical experience with polytetrafluoroethylene (PTFE) monocusp valves [33–36] encouraged us to consider a new method of reconstruction with this material. This manuscript reviews our initial experience in 41 consecutive patients treated with RVOT reconstruction utilizing a new surgically created polytetrafluoroethylene bicuspid pulmonary valve.
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Material and Methods |
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Patient selection criteria for this specific procedure included patient age and size adequate to accommodate a 24-mm-orifice prosthesis, usually 8 to 10 years and older. Preoperative New York Heart Association Classification (NYHA) was I in 7 of 41 patients, II in 30 of 41 patients, and III in 4 of 41 patients. Physiologic indications for surgery included moderate to severe PI in 34 patients, PS in 4 patients, and mixed PI/PS in 3 patients. Preoperative right ventricular end diastolic dimension (RVEDD) average was 32.29 mm. Nearly all the patients (40 of 41 [97.6%]) had previous cardiac surgery and required resternotomy. Preoperative pulmonary hypertension, defined as pulmonary artery pressure greater than 50% of systemic, was noted in 1 patient with distal pulmonary branch stenosis. Early in the study period, preoperative cardiac catheterization was performed routinely; but more recently, magnetic resonance imaging or computed tomography has been used for definition of branch pulmonary anatomy. Other associated procedures included atrial septal defect repair (6), tricuspid valve repair (5), branch pulmonary artery reconstruction (plasty) (5), ventricular septal defect repair (1), cryoablation (1), coronary artery bypass grafting (CABG) (1), and patent ductus arteriosus ligation (1).
Our current strategy for RVOT reconstruction utilizes a PTFE bicuspid pulmonary valve for patients with a pulmonary valve annulus size large enough to accommodate a 24-mm orifice prosthesis. In babies and smaller children, we utilize a PTFE monocusp pulmonary valve or a homograft for RVOT reconstruction.
Surgical Technique
A bicuspid pulmonary valve with orifice size 24 mm or greater is created with PTFE and sutured into the RVOT. To obviate the need for reoperation in growing children, this technique is limited to older children and adults.
The surgical technique included standard cardiopulmonary bypass and mild hypothermia with bicaval cannulation or a single dual stage venous drainage cannula. Aortic cross clamping was usually not employed unless a residual septal defect was present. Vacuum-assisted venous drainage is routinely utilized. Deairing is facilitated by CO2 insufflation into the operative field.
A surgically prepared 0.6 mm PTFE bicuspid valve [Figs 1A–C], with opposing attached leaflets that are shaped like a bishop's hat, is created. A vertical right ventriculotomy is made and extended into the main pulmonary artery [Fig 2A]. The superior margins of the leaflets usually are sewn to the true annulus level but occasionally slightly lower in the RVOT to allow for a larger prosthesis [Fig 2B]. The length of the free edge of the leaflets is approximately 1.5 times the diameter of the outflow tract or annulus upon completion [Figs 2C and 2D]. This leaflet redundancy allows for adequate excursion of the leaflets and minimizes outflow tract gradients, while maximizing coaptation and competency of the valve. The resultant RVOT defect is closed with a transannular patch of treated pericardium or other suitable patch material [Fig 2E]. Sinus rhythm is maintained throughout the procedure and the patients are usually weaned off cardiopulmonary bypass on milrinone infusion at 0.5 micrograms per kilogram per minute. Generally, patients are extubated in the operating theater or shortly thereafter. Daily low dose aspirin is used postoperatively to minimize neointimal hyperplasia.
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A registry and database (a component of the CardioAccess International Clinical Outcomes Database: Comprehensive Cardiovascular and Thoracic Module, CardioAccess Inc, St. Petersburg, FL, and Fort Lauderdale, FL: http://www.cardioaccess.com) has been prospectively maintained on all patients and has been utilized for data collection and analysis.
Follow-up was performed utilizing the CardioAccess database, office charts, and phone interviews. Follow-up variables analyzed included latest follow-up NYHA classification status, latest follow-up echocardiographic quantification of PI (grades 1 to 4), and latest follow-up echocardiographic measurement of RVEDD.
Statistical analysis of continuous variables is by the paired t test and the analysis of categorical variables is by the Wilcoxon signed rank test. Significant differences were considered for p < 0.05.
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Results |
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Hospital and 30 day mortality was 0%. Median hospital length of stay was 5 days (range, 3 to 15 days; mean, 5.8 days). All patients had discharge echocardiograms demonstrating stable PTFE bicuspid valve function.
All patients underwent follow-up echocardiography with the duration of time between operation and the most recent echocardiogram ranging from 0.2 to 3.1 years (median follow-up of 1.5 years, mean follow-up of 1.4 years). Follow-up revealed significant improvement in NYHA classification, PI, and RVEDD.
One patient required reoperation for dehiscence of the leaflet and was felt to have abnormally friable tissue and possibly subclinical infection. Patients experienced an improvement in NYHA status from 1.9 to 1.1 (p < 0.001) [Fig 3]. The arrhythmia resolved in the one patient that had preoperative ventricular tachycardia and underwent cryoablation with bicuspid pulmonary valve replacement.
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Comment |
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Good evidence exists that RV dilatation and dysfunction is reversible following pulmonary valve replacement [3–6, 9, 10]. Unfortunately, recent data suggest a lack of significant recovery of RV indices following pulmonary valve replacement in adults with long standing PI [8]. Therefore, the timing of pulmonary valve replacement is of major importance in the overall maintenance of ventricular function and optimal long-term outcomes. Additionally, a program of aggressive pulmonary valve replacement, in conjunction with intraoperative cryoablation, is effective in decreasing QRS duration and controlling ventricular arrhythmias in tetralogy of Fallot patients with severe PI [39]. In general, our indications for pulmonary valve replacement are evolving but currently include patients with moderate to severe pulmonary insufficiency and/or stenosis and any of the following problems: (1) exertional symptoms of NYHA Class II or greater; (2) RV dysfunction and/or dilatation; (3) decreased performance capacity on exercise testing; (4) ventricular arrhythmias and/or QRS duration greater than 160 ms.
Considerable debate exists regarding what type of valve or reconstruction is optimal for the pulmonary position. A vast array of materials and methods has been utilized [11–32]. Most commonly, recent series support the use of homografts as well stented and unstented heterograft valves for pulmonary valve replacement [11–25]. Despite definite early patient improvement, all biological valve reports have within them a significant incidence of recurrent valvar insufficiency and/or obstruction. A recent study [10] of 36 patients utilizing homografts [31] and heterografts [5] for pulmonary valve replacement noted 9 of 34 patients developed moderate to severe PI and 17 of 34 patients developed significant obstruction within 80 month follow-up. In a similar study, the reported incidence of homograft insufficiency was 50% mild and 28% moderate to severe within a 4.9 years follow-up [14]. Our own experience with homografts has been suboptimal with early development of PI as well as obstruction. Recent evidence [40] suggests an immunologic basis for this early graft failure pattern.
In light of the above, our interest shifted to a nonimmunologic, nondegenerating, and relatively durable material such as PTFE for pulmonary valve replacement [33–36]. Experience with 19 patients followed from 3 to 16.1 years utilizing a PTFE monocusp for RVOT reconstruction suggests reasonable long-term durability and freedom from degeneration [34]. A larger experience [35], consisting of 115 patients using a PTFE monocusp for RVOT reconstruction, with follow-up from 6 months to 8 years, mean 2.6 years, demonstrated no stenosis, calcification, or embolization. There was, however, significant development of PI graded as moderate to severe after 35 months in this monocusp study.
An experimental study demonstrated superior function of a bicuspid over a monocuspid patch for reconstruction of a hypoplastic pulmonary root in pigs, with less pulmonary insufficiency in bicuspid versus monocuspid patches [41]. In Sao Paulo, Brazil, RVOT reconstruction in patients with tetralogy of Fallot was accomplished using a bicuspid porcine pulmonary prosthesis with an alternative design different from the bicuspid PTFE pulmonary valve presented in this manuscript. This bicuspid porcine pulmonary prosthesis was found to be a simple, reliable procedure with good results in postoperative medium term follow-up [42].
In Japan, Yamagishi and Kurosawa [43] have created and implanted more than 200 bicuspid PTFE valves also utilizing an alternative design different from the bicuspid PTFE pulmonary valve presented in this manuscript and similar to the porcine valves described and pictured in the article by Maluf and colleagues [42] from Sao Paolo, Brazil. With follow-up of up to 14 years, echocardiography demonstrates that 80% of the valves are still moving (personal communication with Hiromi Kurosawa at The fourth meeting of The International Working Group for Mapping and Coding of Nomenclatures for Pediatric and Congenital Heart Disease [Nomenclature Working Group], Recife, Brazil, December 10 to 14, 2003). Two important differences exist between his valve and our valves. First, his valves are made with 0.1 mm PTFE while ours are made with 0.6 mm PTFE. Second, his valve does not go all the way around the annulus; instead, his PTFE valve is more of a transannular patch encompassing two thirds of the circumference of the annulus.
Our technique of bicuspid PTFE pulmonary reconstruction essentially utilizes opposing attached 0.6 mm PTFE monocusps [Figs 1 and 2] and is used in patients of adequate age and size to accommodate a 24 mm orifice (usually 8 to 10 years of age and older). This "adult" size was selected for the effective orifice to be large enough such that the valve would not be "outgrown." The proper construction of the valve from a single sheet of PTFE, and the correct implant technique, maintaining the attachments of the leaflets to each other, is felt to enhance competency over time. This expectation is based on the assumption that the opposing leaflets and resultant generous area of coaptation will distribute stresses over a large surface contributing to stability and durability. In addition, as long as the leaflets retain their pliability, obstruction should not be a problem. There is therefore the theoretical possibility that reoperative surgery will not be needed for quite some time, if at all.
Our experience with the PTFE bicuspid pulmonary valve has been favorable. The morbidity is low and there was no mortality in the series. Most of the patients benefited with either trace or mild residual PI and nonsignificant outflow tract gradients. The NYHA symptomatic class improved in the vast majority of patients [Fig 3] and RVEDD decreased significantly (p < 0.05) [Fig 5]. Qualitative echocardiographic evaluation demonstrates a slightly thickened, pliable, and stable valve mechanism thus far. In one case, a dehiscent valve required reoperation in a patient with poor tissue strength and questionable subclinical infection. No evidence supports any valvar degeneration or breakdown of the leaflets. Overall patient satisfaction has been quite good.
Admittedly, this study has all of the known limitations of a retrospective review. Furthermore, MRI and more refined two-dimensional and even three-dimensional echocardiographic studies would have added additional value regarding evaluation of right ventricular function and dimensions as well as the PTFE valve mechanics. Moreover, routine use of exercise testing and assessment of VO2 uptake would better evaluate the functional benefits of this technique. Nevertheless, polytetrafluoroethylene bicuspid pulmonary valve reconstruction of the right ventricular outflow tract is a safe, effective, and durable technique for the short term. Appropriate oversizing minimizes outflow tract obstruction while maximizing competence. This technique is theoretically attractive in that the bicuspid PTFE valve may be amenable to percutaneous dilatation in the event of late stenosis. Furthermore, it may be simpler to perform percutaneous pulmonary valve implantation with the bicuspid PTFE valve than it would be with a bioprosthesis supported with a rigid annulus. Clearly, long-term follow-up is necessary to determine the true value of this technique.
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Summary |
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TopAbstractIntroductionMaterial and MethodsResultsCommentSummaryAcknowledgmentsReferences |
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Acknowledgments |
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TopAbstractIntroductionMaterial and MethodsResultsCommentSummaryAcknowledgmentsReferences |
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References |
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  G. R. Nunn, J. Bennetts, and E. Onikul Durability of hand-sewn valves in the right ventricular outlet. J. Thorac. Cardiovasc. Surg., August 1, 2008; 136(2): 290 - 296. [Abstract] [Full Text] [PDF]
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T. Miyazaki, M. Yamagishi, A. Nakashima, K. Fukae, T. Nakano, H. Yaku, and H. Kado Expanded polytetrafluoroethylene valved conduit and patch with bulging sinuses in right ventricular outflow tract reconstruction J. Thorac. Cardiovasc. Surg., August 1, 2007; 134(2): 327 - 332. [Abstract] [Full Text] [PDF]
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= preoperative; 
= latest follow-up.
