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Ann Thorac Surg 1997;64:1678-1680
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Influence of Pulmonic Position on Durability of Bioprosthetic Heart Valves

Department of Thoracic and Cardiovascular Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan

Accepted for publication May 8, 1997.

	Abstract

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Background. The insertion of bioprosthetic valves into the pulmonic position is not performed commonly because of uncertainty concerning the necessity and durability of such valves.

Methods. We reviewed the long-term outcome of 10 patients who underwent pulmonary valve replacement with bioprostheses between March 1985 and March 1997. A Carpentier-Edwards supraannular bioprosthesis was used in 7 patients, a Hancock II bioprosthesis was used in 2 patients, and a Carpentier-Edwards pericardial bioprosthesis was used in 1 patient. The mean patient age at the time of pulmonary valve replacement was 38.9 ± 16.3 years (range, 15 to 63 years). The diagnoses were pulmonary valvular regurgitation after corrective surgery for tetralogy of Fallot in 7 patients, right ventricular outflow tract stenosis and absent right pulmonary artery combined with a double-outlet right ventricle in 1 patient, pulmonary valvular regurgitation with pulmonary artery dilatation in 1 patient, and aortic valve stenosis treated with our modification of the Ross procedure using a pulmonary bioprosthesis in 1 patient. Survivors were followed up for a mean of 5 years and 5 months.

Results. One patient underwent reoperation because of infective endocarditis of the bioprosthesis. No bioprosthetic valve dysfunction has been observed on Doppler echocardiography during a maximum follow-up period of 12.2 years, except in the patient who underwent replacement at 15 years of age.

Conclusions. Bioprostheses in the pulmonic position are durable in adult patients because they face a minimal hemodynamic load, but they may undergo early leaflet degeneration in younger patients.

	Introduction

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
See also page 1680.

The usefulness of inserting prosthetic valves into the pulmonic position is controversial. In children, a variety of problems leading to brief longevity, including size mismatch, growth, and rapid calcification, have interfered with the pulmonic placement of bioprostheses. For adult patients, however, there appears to be no reason why pulmonary valve replacement (PVR) should not be performed if the durability of the valve in the pulmonic position is demonstrated. The purpose of this study was to demonstrate the durability of bioprostheses in the pulmonic position, especially in adult patients.

	Patients and Methods

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Between March 1985 and March 1997, 10 patients with a mean age of 38.9 ± 16.3 years (range, 15 to 63 years) underwent PVR with bioprostheses. They included 6 men and 4 women. Pulmonary valve replacement with a bioprosthesis was performed for residual severe pulmonary valve regurgitation (PR) after repair of tetralogy of Fallot in 7 patients, for right ventricular outflow tract (RVOT) stenosis and the absent right pulmonary artery with a double-outlet right ventricle in 1 patient, and for PR with pulmonary artery dilatation in 1 patient. The Ross procedure with a bioprosthesis in the pulmonic position was performed for aortic valve stenosis in the 1 remaining patient, who had an active life-style. The preoperative New York Heart Association functional class was III for 6 patients, IV for 3 patients, and II for the 1 patient who underwent the Ross procedure. Second-generation bioprostheses were used in all patients: a Carpentier-Edwards supraannular bioprosthesis in 7 patients; a Carpentier-Edwards pericardial bioprosthesis in 1 patient, and a Hancock II bioprosthesis in 2 patients. The mean valve size was 24.8 ± 2.6 mm (range, 23 to 31 mm).

Concomitant procedures included RVOT patching in 5 patients, tricuspid valve replacement in 1 patient, tricuspid annuloplasty in 1 patient, our modification of the Cox maze procedure [1] in 1 patient, and the Ross procedure in 1 patient (Table 1). Warfarin sodium anticoagulation was initiated after the removal of chest tubes in all patients, and was discontinued 3 months after PVR. We were able to follow up all the patients, with the exception of 1 who died early, for a mean of 5 years and 5 months (range, 0.1 to 12.2 years).

Results are given as means ± standard deviations. The Wilcoxon single-rank test was used to compare values before and after PVR. A p value of less than 0.05 was considered to be significant. Kaplan-Meier's method was used for actuarial analysis.

The indication for PVR for the patient with a double-outlet right ventricle was RVOT obstruction with a peak systolic pressure gradient of 132 mm Hg. For the 8 patients with PR, indications for PVR were progressive exercise intolerance in 6 patients and progressive cardiomegaly in 2 patients. The Ross procedure with a pulmonary bioprosthesis was considered to be indicated for adult patients with aortic valvular disease who had a long life expectancy.

	Results

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
There was 1 hospital death due to low cardiac output syndrome, but no late deaths. The 10-year actuarial survival rate, including the operative death, was 90% ± 9.5%. One of the patients underwent reoperation because of prosthetic valve endocarditis 3 months after PVR. Of the 9 patients who survived, the postoperative New York Heart Association functional class improved to I or II in 7 (77.8%) and to III in 2 (22.2%).

Postoperative cardiac catheterization revealed a mean diastolic pulmonary artery pressure of 9.8 ± 5 mm Hg (range, 6 to 20 mm Hg) and a mean diastolic transprosthetic pressure gradient of 9.4 ± 5 mm Hg (range, 6 to 20 mm Hg). These findings showed that the prosthetic valve in the pulmonic position is exposed to mild hemodynamic stress on closure. In 8 of 9 patients (excluding the patient who underwent the Ross procedure), the mean RV end-diastolic pressure of 13.3 ± 7.3 mm Hg before operation decreased significantly to 5.8 ± 2.3 mm Hg after operation (p = 0.012). The mean RV ejection fraction of 0.50 ± 0.15 before operation increased to 0.54 ± 0.08 after operation (p = 0.116).

On the most recent echocardiographic examination after PVR, the peak gradients across the prostheses averaged 14.9 ± 11.2 mm Hg (range, 7.4 to 41.7 mm Hg), and the mean gradients averaged 5.8 ± 3 mm Hg (range, 3.3 to 12.8 mm Hg). There were 3 patients who had undergone PVR more than 9 years earlier, excluding the patient who underwent a second PVR. Of these 3 patients, the 1 who had undergone PVR at 15 years of age exhibited restricted cusp motion, suggesting bioprosthetic dysfunction, with a peak gradient across the prosthesis of 41.6 mm Hg. In the other 2 patients, there were no signs of structural deterioration or nonstructural dysfunction of the prostheses.

	Comment

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Because it is possible to achieve stable hemodynamics in the acute stage after RVOT reconstruction in tetralogy of Fallot using a transannular patch, few investigators recommend the insertion of a prosthetic valve into the pulmonic position. Fiore and colleagues [2] noted that PR would not affect RV function or hemodynamics. They reported favorable results with the use of a nonvalved right ventricular-pulmonary extracardiac conduit. However, others have found that RV dysfunction develops in patients with severe residual PR after repair of tetralogy of Fallot [3]. Ilbawi and associates [4] emphasized that PVR for PR improved symptoms and exercise tolerance, and made arrhythmias easier to control. Misbach and co-workers [5] stated that insertion of a prosthesis into a previously reconstructed RVOT for tetralogy of Fallot can be done with little risk, because it does not require a new ventriculotomy or aortic cross-clamping. Bove and colleagues [6] also reported that PVR improved the RV ejection fraction and reduced the RV end-diastolic dimension. In our study, the RV ejection fraction increased, the RV end-diastolic pressure significantly decreased, and the New York Heart Association functional class improved markedly after PVR. These findings objectively demonstrate improvement in RV function and confirm the usefulness of this procedure.

In a study of porcine bioprostheses, Burdon and associates [7] hypothesized that the velocity and direction of ventricular chamber flow facing the valve on closure were the major reasons for the earlier structural deterioration of bioprostheses in the mitral position compared with the aortic position. Nakano and co-workers [8] reported that the actuarial rate of freedom from structural deterioration of tricuspid Carpentier-Edwards pericardial bioprostheses was 100% at 9 years after operation. Cohen and associates [9] reported that bioprostheses in the mitral position exhibited more severe leaflet degeneration than did those in the tricuspid position. Nakanishi and colleagues [10] reported that structural deterioration of mitral bioprostheses included tears or perforations around the commissure. These findings suggest that hemodynamic factors are directly responsible for the destruction of bioprostheses [11]. Thus, bioprostheses appear to exhibit progressively less durability in the mitral, aortic, and tricuspid positions, because the closing stress increases in the sequence of right ventricular systolic, aortic diastolic, and left ventricular systolic pressures. Because the diastolic transprosthetic pressure gradient, which is the closing stress in the pulmonic position, was very low in our study, mechanical destruction of pulmonic bioprostheses appears unlikely to progress. Hence, the pulmonic bioprosthesis can be predicted to have good longevity in adults.

In 8 of 9 patients (excluding the patient who underwent a second PVR), no hemodynamic signs of structural deterioration were observed, but in 1 patient who underwent PVR at 15 years of age, the peak gradient across the prosthesis was increased and cusp motion was restricted on echocardiography. This suggests that younger age at the time of operation strongly increases the risk of bioprosthetic deterioration, even in the pulmonic position.

Although a pulmonary and aortic allograft appears to be best for reconstruction of the RVOT at present [12], in countries such as Japan, this material is not readily available. We recently performed the Ross procedure with insertion of a bioprosthesis into the pulmonic position, and the patient's postoperative course was very good, with minimum neoaortic (allograft) and neopulmonic (bioprosthesis) gradients. We aimed to make this modification of the Ross procedure the final operation for this patient.

Our findings suggest that although careful selection of candidates is important for PVR with bioprostheses, especially for younger patients, this procedure is useful for adult patients who require RVOT reconstruction.

	Footnotes

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 
Address reprint requests to Dr Fukada, Department of Thoracic and Cardiovascular Surgery, Sapporo Medical University School of Medicine, South 1, West 16, Chuo-ku, Sapporo, Hokkaido 060, Japan.

	References

Top Footnotes Abstract Introduction Patients and Methods Results Comment References

 

1. Abe T, Kuwaki K, Mawatari T, et al. Maze operation for chronic atrial fibrillation with valvular disease. Jpn J Thorac Surg 1996;49:709–15.
2. Fiore AC, Peigh PS, Robinson RJ, Glant MD, King H, Brown JW. Valved and nonvalved right ventricular-pulmonary arterial extracardiac conduits. J Thorac Cardiovasc Surg 1983;86:490–7.[Abstract]
3. Oku H, Shirotani H, Sunakawa A, Yokoyama T. Postoperative long-term results in total correction of tetralogy of Fallot: hemodynamics and cardiac function. Ann Thorac Surg 1986;41:413–8.[Abstract]
4. Ilbawi MN, Idriss FS, Muster AJ, Wessel HU, Paul MH, DeLeon SY. Tetralogy of Fallot with absent pulmonary valve. J Thorac Cardiovasc Surg 1981;81:906–15.
5. Misbach GA, Turley K, Ebert PA. Pulmonary valve replacement for regurgitation after repair of tetralogy of Fallot. Ann Thorac Surg 1983;36:684–91.[Abstract]
6. Bove EL, Kavey RW, Byrum CJ, Sondheimer HM, Blackman MS, Thomas FD. Improved right ventricular function following late pulmonary valve replacement for residual pulmonary insufficiency or stenosis. J Thorac Cardiovasc Surg 1985;90:50–5.
7. Burdon TA, Miller DC, Oyer PE, et al. Durability of porcine valves at fifteen years in a representative North American patient population. J Thorac Cardiovasc Surg 1992;103:238–52.
8. Nakano K, Eishi K, Kosakai Y, et al. Ten-year experience with the Carpentier-Edwards pericardial xenograft in the tricuspid position. J Thorac Cardiovasc Surg 1996;111:605–12.
9. Cohen SR, Silver MA, McIntosh CL, Roberts WC. Comparison of late (62 to 140 months) degenerative changes in simultaneously implanted and explanted porcine (Hancock) bioprostheses in the tricuspid and mitral valve positions in six patients. Am J Cardiol 1984;53:1599–1602.[Medline]
10. Nakanishi K, Kazui T, Morikawa M, et al. Evaluation of bioprosthetic valve reoperations in the mitral position. Jpn J Artif Organs 1988;17:1141–4.
11. Jamieson WRE, Rosado LJ, Munro AI, et al. Carpentier-Edwards standard porcine bioprosthesis: primary tissue failure (structural valve deterioration) by age groups. Ann Thorac Surg 1988;46:155–62.[Abstract]
12. Bando K, Danielson GK, Schaff HV, Mair DD, Jursrud PR, Puga FJ. Outcome of pulmonary and aortic homografts for right ventricular outflow tract reconstruction. J Thorac Cardiovasc Surg 1995;109:509–18.[Abstract/Free Full Text]

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Tomio Abe Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fukada, J. Articles by Abe, T. Search for Related Content PubMed PubMed Citation Articles by Fukada, J. Articles by Abe, T. Related Collections Related Article