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Ann Thorac Surg 2007;84:2047-2050. doi:10.1016/j.athoracsur.2007.06.078
© 2007 The Society of Thoracic Surgeons
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Original Articles: Cardiovascular

Follow-Up of Shelhigh Porcine Pulmonic Valve Conduits

Woong-Han Kim, MDa, Sun Kyung Min, MDa, Chang Hyu Choi, MDa, Jeong Ryul Lee, MDa, Yong Jin Kim, MDa,*, Eun-Jung Bae, MDb, Chung Il Noh, MDb

a Department of Thoracic and Cardiovascular Surgery, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea
b Department of Pediatric Cardiology, Seoul National University College of Medicine, Seoul National University Children’s Hospital, Seoul, Korea

Accepted for publication June 26, 2007.

* Address correspondence to Dr Yong Jin Kim, Department of Thoracic and Cardiovascular Surgery, Seoul National University Children’s Hospital, 28 Yongon-dong, Jongro-gu, Seoul, 110-744, Korea (Email: kyj{at}plaza.snu.ac.kr).

Presented at the Poster Session of the Forty-third Annual Meeting of The Society of Thoracic Surgeons, San Diego, CA, Jan 29–31, 2007.


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 References
 
Background: We implanted Shelhigh porcine pulmonic valve conduits because of the limited availability of homografts in our country. The aim of this study was to evaluate the short-term results of SPVC.

Methods: From November 2002 to July 2005, the Shelhigh porcine pulmonic valve conduit was implanted in 73 patients (81 procedures) in the right ventricular outflow tract to correct congenital heart diseases. Operative procedures were Rastelli operation in 65, anatomic correction of atrioventricular discordance in 5, and Ross operation in 3. Age at operation was 6.8 ± 7.5 years, including 11 patients under 1 year. The median conduit size was 18 mm (range, 12 to 24 mm).

Results: There was no operative mortality and 1 nonconduit-related late death (mean follow-up, 11.3 ± 10.7 months). Ten conduits (12.3%, 7 patients) were removed at a median of 9.6 months (range, 2.5 to 25.4) owing to obstruction in 9 and pseudoaneurysm in 1. In the explanted conduits, we found a prominent intimal peel at the distal anastomosis without leaflet calcification. Freedom from reoperation at 24 months was 87% ± 11.7% in large-sized conduits (≥18 mm) and 62.8% ± 10.6% in small-sized conduits (≤16 mm). Especially, 12-mm sized conduit showed 33.3% freedom from reoperation during the first 12 months of follow-up.

Conclusions: On the basis of our short-term results, Shelhigh porcine pulmonic valve conduits are not satisfactory. Small-sized conduits (≤16 mm) fail earlier; large-sized conduits (≥18 mm) fail after 2 years of implantation due to intimal peel formation at the distal segment.


   Introduction
Top
 Abstract
 Introduction
Material and Methods
 Results
 Comment
 References
 
To reconstruct right ventricular (RV) to pulmonary artery (PA) continuity, several types of conduits have been developed [1]. But the result was not satisfactory for calcific stenosis, fibrointimal peel formation, and lack of growth potential [2–6]. Cryopreserved pulmonic homografts are most commonly used [6, 7], but we implanted Shelhigh No-React (Shelhigh, Millburn, New Jersey) porcine pulmonic valved conduits (SPVC) because of the limited availability of homografts in our country.

In this report, we describe our experience and short-term results with the use of SPVC for patients requiring right ventricular-to-pulmonary artery connection as a part of biventricular complete repair of various congenital heart diseases.


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 References
 
Patients
From November 2002 to July 2005, the SPVC was implanted to 73 patients (81 procedures) in the right ventricular outflow tract to correct congenital heart diseases. The average age at operation was 6.8 ± 7.5 years (range, 0.2 to 30.8; median, 4.3), and 11 patients were less than 1 year old. The mean body weight was 22.0 ± 19.4 kg (range, 4.4 to 76.3 kg; median, 14.0 kg). Forty-two patients were boys and 31 were girls.

This study was approved by the Seoul National University Hospital Institutional Review Board (study approval number H-0601-069-167), and the individual consent for the study was waived. The primary diagnoses of the patients are shown in Table 1.


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  		Table 1 Patient Diagnoses
 
Surgical Technique
Operative procedures were Rastelli operation in 65 patients, anatomic correction of atrioventricular discordance in 5 patients, and Ross operation in 3 patients. Concomitant pulmonary artery angioplasty was performed in 25 patients, and unifocalization of major aortopulmonary collateral arteries in 6 patients.

The distal anastomosis was performed with a continuous polypropylene suture. After vertical ventriculotomy, the proximal end of SPVC was anastomosed to the ventricle in a same way.

In all, 81 SPVCs ranging from 12 to 24 mm were implanted, including eight conduits for reoperation (Table 2). The average size was 18.7 ± 8.5 mm (median, 18 mm). The choice of conduit size was selected by the patient’s body weight, body surface area, and matched pulmonary artery diameter. When the mediastinal space allowed, larger conduit was implanted to accommodate the patient’s growth.


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  		Table 2 Used Conduits
 
Statistical Data
The primary outcome variables for this study were times to death and reoperation. Reoperation included only the reoperation for conduit problems. Probabilities of freedom from reoperation were estimated by means of the Kaplan-Meier method. All statistical analyses were performed using SPSS version 10.0 software (SPSS, Chicago, Illinois). Statistical significance was declared at p less than 0.05.


   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 References
 
Follow-up was complete in all patients, with a mean duration of 11.3 ± 10.7 months. There was no operative mortality and 1 nonconduit-related late mortality. The late death was related to the patient’s previous condition (Alagille syndrome) 2 years after initial Rastelli operation and unifocalization for pulmonary atresia with major aortopulmonary collateral arteries.

In all, 81 SPVC were implanted in 73 patients, and 10 conduits were removed from 7 patients after implantation. Two conduits were removed from a patient with corrected transposition of great arteries. An SPVC of 14 mm was replaced with a 16-mm conduit at 14 months after initial Rastelli operation, and the 16-mm conduit was replaced with same-sized conduit at 15 months after reoperation. Three conduits were removed from a patient with pulmonary atresia with major aortopulmonary collateral arteries. Two 12-mm conduits and one 14-mm conduit were removed at 2.6 months, 4.4 months, and 8.4 months interval of the previous operation. In 2 of the 7 patients who underwent reoperation, SPVCs were replaced with nonvalved tube grafts.

The most common indication for conduit replacement was conduit stenosis, which was present in 9 cases. Echocardiographic evaluation at the time of conduit change in all of the patient with conduit stenosis demonstrated that the mean peak gradient across the conduit was 79 ± 18.1 mm Hg (median, 70 mm Hg; range, 60 to 100 mm Hg). The other indication was right ventricular outflow tract pseudoaneurysm formation in 1 case.

The median time to conduit failure in this series was 9.6 months (range, 2.6 to 25.4). The overall freedom from reoperation at 24 months is 77.1% ± 7.3%. Kaplan-Meier estimates of freedom from reoperation for all grafts over time is shown in Figure 1. The freedom from reoperation at 24 months was 87% ± 11.7% in large-sized conduit (≥18 mm) and 62.8% ± 10.6% in small-sized conduit (≤16 mm). In our experiences, early failures occurred in most 12-mm sized conduits within 1 year of implantation, and this resulted in only 33.3% freedom from reoperation at 12 months. This kind of failure pattern also happened in large-sized conduits (≥18 mm) after 2 years of operation. So there was no statistical difference in freedom from reoperation rate at more than 2 years after implantation between small- and large-sized conduit (p = 0.12). Their Kaplan-Meier estimates of freedom from reoperation are shown in Figure 2.


Figure 1
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  		Fig 1. Kaplan-Meier estimates of freedom from reoperation for all grafts over time. The freedom from reoperation at 2 years is 77.1% ± 7.3%.

 

Figure 2
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  		Fig 2. Kaplan-Meier estimates of freedom from reoperation according to conduit size.

 
In the explanted conduits, we found prominent intimal peel formation at the distal anastomosis (Fig 3). All patients who needed reoperation showed distal intimal peel formation except 1 patient who had pseudoaneurysm. Valve leaflet calcification and degenerative change were not found in most reoperation cases (Fig 4). The pathology findings were consistent with chronic inflammation and foreign body reaction with fibrosis. The intimal fibrotic tissue contained multinucleated giant cells, lymphoplasmocytes, and eosinophils.


Figure 3
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  		Fig 3. Extensive intimal proliferation at the distal anastomosis.

 

Figure 4
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  		Fig 4. Explanted Shelhigh porcine pulmonic valve conduits without leaflet calcification or degenerative change.

 

   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
References
 
Placement of valved conduit in the right ventricle to pulmonary artery circulation during repair of congenital heart diseases is problematic in that most of these prostheses will eventually require replacement [2]. The main issue is longevity of prosthetic valved conduits and the rate of reoperation. Cryopreserved homograft valved conduits are most commonly used [6–8], but have limited availability especially in small conduit sizes. Therefore, there is great interest in always available alternatives to homograft.

Classical complications of previously used conduits made of synthetic tubes as supportive housing for a biological valve are focal valvular stenosis, conduit kinking, sternal compression, and diffuse stenosis [4, 7]. Some papers report acceptable results of stentless porcine valved conduits with a bovine pericardium extension, processed with glutaraldehyde and detoxified by the No-React process by Shelhigh [9–12]. We implanted Shelhigh No-React porcine pulmonic valved conduits because of the limited availability of homograft in our country.

The short-term results of SPVC are not favorable. The overall freedom from reoperation at 2 years is 77.1%, and 62.8% in small-sized conduit (≤16 mm). In many conferences, including those of pediatric cardiac surgeons, pediatric cardiologists, and radiologists, there has been discussion about the cause of rapid intimal peel formation at distal anastomosis of SPVC. As some studies suggest an intrinsic immunologic response like foreign-body type reaction [13, 14], anti-inflammatory medication was added to anticoagulation drugs postoperatively. And it seems likely that surgical technique related problems play a role. The length of SPVC valvar portion was too long in small infants, and the shape of conduit was relatively straighter than the right ventricular outflow tract of patients. Rheologic factors including pulmonary artery angulation or turbulence at anastomosis site were also problematic. Thus, we thought that modification of surgical technique might be helpful to decrease intimal peel formation at the distal conduit. Fineer suture materials and outer-in technique for smooth inner surface were used to prevent turbulence and thrombus formation at the suture line. When we chose the size of conduit and tailored the end of the conduit for anastomosis, more strict matching of the size and length of the conduit to the patient was performed to avoid conduit redundancy or compression to pulmonary artery. But as we could not improve the short-term results of SPVC by technical modification or medications, we have to find other alternative valved conduits for right ventricle to pulmonary artery reconstruction.

In conclusion, on the basis of our short-term results, SPVC are not satisfactory. Small-sized conduit (≤16 mm) failure occurred earlier, and large-sized conduit (≥18 mm) failure occurred after 2 years of implantation owing to intimal peel formation at distal conduit.


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 References
 

  1. Lange R, Weipert J, Homann M, et al. Performance of allografts and xenografts for right ventricular outflow tract reconstruction Ann Thorac Surg 2001;71(Suppl):365-367.
  2. Caldarone CA, McCrindle BW, Van Arsdell GS, et al. Independent factors associated with longevity of prosthetic pulmonary valves and valved conduits J Thorac Cardiovasc Surg 2000;120:1022-1031.[Abstract/Free Full Text]
  3. Sinzobahamvya N, Wettwe J, Blaschczok HC, Cho MY, Brecher AM, Urban AE. The fate of small-diameter homografts in the pulmonary position Ann Thorac Surg 2001;72:2070-2076.[Abstract/Free Full Text]
  4. Molina JE, Edwards JE, Bianco RW, Clack RW, Lang G, Molina JR. Composite and plain tubular synthetic graft conduits in right ventricle-pulmonary artery position: fate in growing lambs J Thorac Cardiovasc Surg 1995;110:427-435.[Abstract/Free Full Text]
  5. Levine AJ, Miller PA, Stumper OS, et al. Early results of right ventricular-pulmonary artery conduits in patients under 1 year of age Eur J Cardiothorac Surg 2001;19:122-126.[Abstract/Free Full Text]
  6. Dittrich S, Alexi-Meskishvili VV, Yankah AC, et al. Comparison of porcine xenografts and homografts for pulmonary valve replacement in children Ann Thorac Surg 2000;70:717-722.[Abstract/Free Full Text]
  7. Wells WJ, Arroyo Jr H, Bremner RM, Wood J, Starnes VA. Homograft conduit failure in infants is not due to somatic growth J Thorac Cardiovasc Surg 2002;124:88-96.[Abstract/Free Full Text]
  8. Perron J, Moran AM, Gauvreau K, del Nido PJ, Mayer JE, Jonas RA. Valved homograft conduit repair of the right heart in early infancy Ann Thorac Surg 1999;68:542-548.[Abstract/Free Full Text]
  9. Vrandecic MOP, Fantini FA, Gontijo BF, Martins CN, Vrandecic E. Porcine stentless valve/bovine pericardial conduit for right ventricle to pulmonary artery Ann Thorac Surg 1998;66(Suppl):179-182.
  10. Marianeschi SM, Iacona GM, Seddio F, et al. Shelhigh No-React porcine pulmonic valve conduit: a new alternative to the homograft Ann Thorac Surg 2001;71:619-623.[Abstract/Free Full Text]
  11. Abolhoda A, Yu S, Oyarzun R, et al. No-React detoxification process: a superior anticalcification method for bioprostheses Ann Thorac Surg 1996;62:1724-1730.[Abstract/Free Full Text]
  12. Abolhoda A, Yu S, Oyarzun R, McCormick JR, Bogden JD, Gabbay S. Calcification of bovine pericardium: glutaraldehyde versus No-React biomodification Ann Thorac Surg 1996;62:169-174.[Abstract/Free Full Text]
  13. Ishizaka T, Ohye RG, Goldberg CS, et al. Premature failure of small-sized Shelhigh No-React porcine pulmonic valve conduit model NR-4000 Eur J Cardiothorac Surg 2003;23:715-718.[Abstract/Free Full Text]
  14. Pearl JM, Cooper DS, Bove KE, Manning PB. Early failure of the Shelhigh pulmonary valve conduit in infants Ann Thorac Surg 2002;74:542-549.[Abstract/Free Full Text]



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