- Email: [email protected]
Early results of valved bovine jugular vein conduit versus bicuspid homograft for right ventricular outflow tract reconstruction
Early Results of Valved Bovine Jugular Vein Conduit Versus Bicuspid Homograft for Right Ventricular Outflow Tract Reconstruction Thierry Bove´, MD, He´le`ne Demanet, MD, Pierre Wauthy, MD, Jacques P. Goldstein, MD, PhD, Hugues Dessy, MD, Pierre Viart, MD, Andre´e Deville´, MD, and Frank E. Deuvaert, MD Cardiac Unit, Hoˆpital Universitaire Des Enfants Reine Fabiola, U.L.B.—V.U.B., Brussels, Belgium
Background. Homograft conduits are preferable for right ventricular outflow tract reconstruction in children, but their limited availability remains a major concern. Recently, a valve-containing segment of bovine jugular vein (Contegra, Medtronic Inc, Minneapolis, MN) has been introduced as a potential alternative conduit. Methods. Early clinical and echocardiographic results of right ventricular outflow tract reconstruction were retrospectively compared between 41 children (mean age, 1.9 years), receiving a Contegra conduit and 36 patients (mean age, 2.7 years) with a size-reduced pulmonary homograft. Results. Clinical outcome was comparable with two early deaths in the homograft group and one in the Contegra group. There were no conduit-related complications in either population. Early echocardiographic assessment showed only trivial to mild regurgitation in 9 homografts versus 17 Contegra conduits. The peak gradient across the right ventricular outflow tract conduit
was comparable for both groups, although a larger number of patients, treated with a downsized homograft, had a small gradient at the distal junction with the pulmonary arteries (12 versus 6 patients). None of the patients had a gradient at the valvar level. Conclusions. The valved bovine jugular vein conduit offers a promising substitute for right ventricular outflow tract reconstruction in infants and children, with an early hemodynamic performance that compares favorably with downsized, bicuspid homografts. Clinical advantages are greater shelf availability and the natural continuity between valve and conduit, which allows proximal infundibular shaping without additional material. However, durability must be determined, even though most of these children will require right ventricular outflow tract reoperation after outgrowing the conduit.
T
Subsequent to the encouraging results obtained in animal models [3, 4], a glutaraldehyde-preserved segment of bovine jugular vein, containing a naturally existing trileaflet valve, has been recently introduced into clinical practice. We have used this new graft for RVOT reconstruction in infants and young children, and we report their preliminary clinical and hemodynamic performance compared with size-reduced, bicuspid pulmonary homografts, which we used previously in the absence of an available, appropriate-sized homograft.
he successful use of a valved homograft conduit for right ventricular outflow tract (RVOT) reconstruction, first described by Ross and Sommerville [1] in 1966, has significantly widened the feasibility of repair of various right-sided congenital heart diseases. Additionally, the growing popularity of the Ross procedure to treat aortic valve disease has implied more frequently the need for RVOT reconstruction. Both techniques have resulted in an increasing demand for homografts, pulmonary ones in particular, because of their superior durability and convenience in the pulmonary circulation [2]. However, despite continuous refinements in preservation and storage techniques, availability remains a limiting factor in the extensive clinical application of homografts, especially for the small-sized grafts required for neonatal and infant recipients, creating a need for alternative conduits.
Presented at the Thirty-eighth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28 –30, 2002. Address reprint requests to Dr Bove´ , Department of Cardiac Surgery, U.Z. Gent, De Pintelaan 185 5K12, 9000 Gent, Belgium; e-mail: [email protected].
© 2002 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
(Ann Thorac Surg 2002;74:536 – 41) © 2002 by The Society of Thoracic Surgeons
Patients and Methods Patients From May 2000 to June 2001, 41 children (29 boys, 12 girls) with a mean age of 1.9 ⫾ 2.6 years (range, 7 days to 13 years) and a mean weight of 8.4 ⫾ 4.4 kg (range, 2.8 to 18 kg) underwent RVOT reconstruction using a valved bovine jugular vein conduit (Contegra group; Medtronic Inc., Minneapolis, MN). This patient population was compared with 36 patients (18 boys, 18 girls), operated on between March 1996 and November 2000, who received a surgically downsized, bicuspid pulmonary homograft 0003-4975/02/$22.00 PII S0003-4975(02)03728-1 21
Table 1. Indication for Right Ventricular Outflow Tract Reconstruction Indication Tetralogy of Fallot PA-VSD Truncus arteriosus TGA-VSD-PS DORV-PS AV/VA discordance-VSD-PS Pulmonary valve stenosis PA-intact septum Ross procedure Total
537
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
Ann Thorac Surg 2002;74:536 – 41
Homograft
Contegra
5 7 7 5 3 2 1 ... 6 36
16 10 5 3 1 ... ... 1 5 41
AV/VA discordance-VSD-PS ⫽ atrioventricular-ventriculoarterial discordance with ventricular septal defect and pulmonary stenosis; DORVPS ⫽ double-outlet right ventricle with pulmonary stenosis; PA-intact septum ⫽ pulmonary atresia with intact ventricular septum; PAVSD ⫽ pulmonary atresia with ventricular septal defect; TGA-VSDPS ⫽ transposition great arteries with ventricular septal defect and pulmonary stenosis.
(HG group) when an appropriately sized conduit was not available in that period. Their mean age was 2.7 ⫾ 2.5 years (range, 6 days to 10 years) and mean weight 10.3 ⫾ 5.1 kg (range, 2.5 to 23 kg). Nine (25%) and 20 (45%) patients younger than 1 year of age (p ⫽ 0.03) were in the HG and Contegra groups, respectively. The primary diagnoses indicating RVOT reconstruction are listed in Table 1. Several patients in both groups had a previous surgical palliation (7 HG versus 8 Contegra patients; p ⫽ 0.85) or an interventional procedure such as aortic and pulmonary valve dilation and embolization of aortopulmonary collaterals (4 HG versus 8 Contegra patients; p ⫽ 0.31). Nine patients underwent a primary correction of their original disease and required the implantation of a valved conduit for early failure of transannular patch repair of tetralogy of Fallot (2 HG; 2 Contegra), structural degeneration of a first homograft (3 HG; 1 Contegra), and recurrent obstruction after infundibular enlargement (1 HG; 0 Contegra). Pulmonary arterial hypertension was present in 11 (31%) patients in the HG group and 6 (15%) patients in the Contegra group (p ⫽ 0.09), and was mainly related to pathologic processes such as truncus arteriosus and pulmonary atresia with ventricular septal defect and aortopulmonary collateral lung perfusion.
Operative Technique All procedures were performed with conventional cardiopulmonary bypass, moderate to deep hypothermia, and cold crystalloid cardioplegia. Deep hypothermic circulatory arrest was needed in 2 patients, who required simultaneous repair of aortic arch anomalies (1 interrupted aortic arch and 1 coarctation). The bovine jugular vein graft was procured as a 12- to 14-cm-long tubular conduit, containing a valve of three semilunar leaflets in its middle third, with a diameter varying from 12 to 22 mm. Despite glutaraldehyde fixa-
tion, the tissue has maintained a remarkable pliability and softness, offering optimal suturing and tailoring characteristics for congenital RVOT repair. Surgical transformation of an adult-sized pulmonary homograft into a bicuspid conduit was achieved by excision of one longitudinal third, containing a cusp, and closure of the newly formed bicuspid conduit by a continuous running suture. Implantation of the downsized conduit as well as the Contegra conduit was performed, respecting the same principles of conduit insertion for RVOT reconstruction: (1) placement of the conduit away from the midline to avoid sternal compression, (2) positioning of the valve as distal as possible, and (3) proximal RVOT enlargement with additional autologous pericardium when a bicuspid homograft was used and using the natural tubular extension of the vein segment for the bovine xenograft. The internal diameter of the implanted size-reduced homografts ranged from 10 to 20 mm, and from 12 to 20 mm for the Contegra conduits. The median size of the selected conduit was 16 mm for both types. Concomitant operative procedures are listed in Table 2. Mean aortic cross-clamp time and cardiopulmonary bypass time were comparable, respectively 65.4 ⫾ 38.2 minutes and 145.1 ⫾ 48.9 minutes in the HG group and 60.5 ⫾ 22.3 minutes and 137.0 ⫾ 32.3 minutes in the Contegra group. The mean right ventricular to left ventricular pressure ratio before sternal closure was 0.53 ⫾ 0.09 in the HG group and 0.53 ⫾ 0.16 in the Contegra group.
Echocardiographic Assessment Transthoracic two-dimensional echocardiography was performed with a 3.5- or 5.0-MHz transducer with a Hewlett-Packard Sonos 5000 Ultrasound system. Early in-hospital evaluation was compared in both types of RVOT reconstruction with particular attention to valve
Table 2. Procedures Associated With Right Ventricular Outflow Tract Reconstruction Homograft BT shunt ligation VSD enlargement PA plasty ASD closure IAA repair Atrial/Arterial Switch Coarctation repair APCA ligation
14 patients
Contegra
16 patients
6 2
BT shunt ligation ASD closure
5 6
2 2 1
PA plasty PAPVR repair RVOT aneurysm resection APCA ligation
4 1 1
1
1
1 2
APCA ⫽ aortopulmonary collateral artery; ASD ⫽ atrial septal defect; BT shunt ⫽ Blalock-Taussing shunt; IAA ⫽ interrupted aortic arch; PA plasty ⫽ pulmonary artery plasty; PAPVR ⫽ partial anomalous pulmonary venous return; RVOT ⫽ right ventricular outflow tract; VSD ⫽ ventricular septal defect.
538
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
Ann Thorac Surg 2002;74:536 – 41
Table 3. Complications Complication Cardiac Low cardiac output ECMO Pulmonary hypertension AV block Pulmonary Neurologic Seizures Hypoxic encephalopathy Renal failure Early reoperation Bleeding VSD enlargement Residual VSD Bidirectional Glenn shunt
Homograft
Contegra
10 (28%) 5 2 5 2 11 (31%) 2 (6%) 1 1 1 (3%) 3 (8%) 1 1 1 ...
8 (20%) 6 2 3 ... 9 (22%) 2 (5%) 1 1 2 (5%) 4 (10%) 2 ... 1 1
AV block ⫽ atrioventricular block; ECMO ⫽ extracorporeal membrane oxygenation; VSD ⫽ ventricular septal defect.
function and presence as location of eventual residual outflow obstruction. The peak gradients were classified as subvalvular, valvular, or distal postvalvular obstruction according to their site, and divided into four groups according to the severity of the gradient: no gradient, a minor gradient less than 15 mm Hg, a gradient between 15 and 30 mm Hg, and a gradient of more than 30 mm Hg.
Statistical Analysis Data are expressed as mean ⫾ standard deviation value or as median value and the range. Variables were compared using the 2 method or Fisher’s exact test. A p value less than 0.05 was considered significant. All statistical analyses were conducted with the StatView 5.0 system (SAS Institute, Cary, NC).
Noteworthy is that 3 children necessitated adjunctive ventricular assistance by extracorporeal membrane oxygenation for refractory right ventricular dysfunction in cases of late referral of tetralogy of Fallot, all of whom survived. Ventilation time, inotropic support duration, and intensive care and hospital stay were, respectively, for the HG and Contegra groups 4.8 ⫾ 7.3 days and 4.1 ⫾ 4.8 days, 4.6 ⫾ 4.7 days and 5.5 ⫾ 5.7 days, 9.9 ⫾ 13.4 days and 8.2 ⫾ 6.2 days, and 17.7 ⫾ 17.4 days and 16.9 ⫾ 8.6 days. These data were not significantly different and independent of the implanted conduit type. All surviving patients showed a remarkable improvement of their functional status and were discharged in New York Heart Association class I or II.
Echocardiographic Outcome The last echocardiographic data, recorded before hospital discharge, showed a competent valve function in the majority of the patients in both groups: 27 (75%) of the HG patients versus 23 (59%) of the Contegra patients (p ⫽ 0.13). Trivial to mild valve leakage was found in 9 patients with a bicuspid homograft, and quantified as grade I regurgitation in 8 patients and grade II in 1 patient. Fifteen children with a Contegra conduit had a grade I valve insufficiency and 2 had a grade II leakage (Fig 1). This difference was not significant (p ⫽ 0.13). There was no specific correlation between valve incompetence and residual pulmonary hypertension. However, regurgitation coincided with some residual distal RVOT obstruction in 5 of the 9 HG patients, and in 4 of the 15 Contegra patients. Regarding the presence of a residual gradient across the reconstructed RVOT, the majority of patients in both groups had no outflow obstruction, ie, 24 (67%) HG patients and 31 (77.5%) Contegra patients (p ⫽ 0.29). In a
Results Clinical Outcome Two patients (6%) died early in the HG group. The first was operated on at the age of 1 week, presenting truncus arteriosus and interrupted aortic arch, and died of persistent pulmonary hypertension, low cardiac output, and acute renal failure. The second underwent a one-stage repair of double-outlet right ventricle with pulmonary stenosis and aortic coarctation under deep hypothermic circulatory arrest, at the age of 8 months. He died on the 12th postoperative day of severe right ventricular failure and atrioventricular block. In the Contegra group 1 patient (2%) died perioperatively after truncus arteriosus repair at the age of 2.5 years, because of intractable pulmonary hypertension (right ventricular to left ventricular pressure ratio ⫽ 1). Regarding overall morbidity, there was no statistically significant difference between the two groups: 18 (50%) patients in the HG group versus 16 (39%) patients in the Contegra group (p ⫽ 0.33). The complications are depicted in Table 3.
Fig 1. Regurgitation distribution. Numbers of patients according to grade of valve insufficiency are shown for the two types of conduits. (HG ⫽ homograft.)
Ann Thorac Surg 2002;74:536 – 41
significantly different number of patients a small gradient of 10 to 15 mm Hg was found in the HG group compared with the Contegra population (9 versus 0 patients; p ⫽ 0.007), and all these peak gradients were measured at the distal anastomotic site. A moderate distal gradient of 15 to 30 mm Hg was present in 3 HG patients versus 4 Contegra patients. A more severe gradient exceeding 30 mm Hg was found at the subvalvular or the distal level in 2 patients in whom RVOT repair was performed with a jugular vein segment. Considering the site of the measured obstruction, most gradients were localized at the distal junction between conduit and recipient pulmonary arteries, ie, 12 patients in the HG group versus 6 patients in the Contegra group (p ⫽ 0.05). This included the cases in which a separate enlarging plasty of the pulmonary branches was achieved: 2 of the 12 HG patients versus 3 of the 6 Contegra patients. Additionally, most of these residual distal obstructions occurred in pathologic processes including pulmonary arborization anomalies such as pulmonary atresia and tetralogy of Fallot: 8 of the 12 in the HG group and 6 of the 6 in the Contegra group. None of the RVOT corrections as part of the Ross procedure, either by a bicuspid homograft or a jugular vein xenograft, showed a residual outflow obstruction. Three patients in the Contegra group had an insufficient relief of the subvalvular hypertrophied infundibulum, with residual gradients of 15, 25, and 30 mm Hg. Finally, no gradient was measured at the valvar level in either of the conduit types. Figure 2 illustrates the distribution and grade of the peak gradients.
Comment Since the successful application of cryopreservation in the mid-1980s, several studies have advocated the use of cryopreserved pulmonary homografts as the conduit of choice for reconstruction of the RVOT [2, 5, 6]. However, the expanding indications for repair of various congenital as well as acquired heart diseases have led to an increasing mismatch between demand and supply, and made availability a limiting factor for the use of homografts, mostly in the smaller sizes for neonatal and infant operations. Moreover, despite better understanding of immunohistologic interactions and refinements of preservation, progressive structural degeneration and outgrowth determined significantly young recipient age and implantation of small-size conduits as risk factors for early homograft failure [6]. Recent long-term analysis of homograft durability revealed that conduits sized smaller than 15 mm usually required earlier explantation [7]. Lange and coworkers [8] found, in a comparative study between allografts and xenograft conduits, that children receiving a conduit smaller or equal to 15 mm commonly needed reoperation within 6 years after implantation because of outgrowth, and concluded that a xenograft might be a justified option in neonates and infants. Also Forbess and associates [9] showed an equivalent shortterm outcome of aortic and pulmonary homografts in
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
539
Fig 2. (A) Grade of obstructive gradient. Numbers of patients according to peak gradient are shown for the two conduits. (B) Level of obstructive gradient. Numbers of patients according to location of the obstruction are shown for the two conduits.
younger patients. These findings should support the speculation that durability and even type of the implanted conduit for RVOT reconstruction should be a less critical issue in younger children who generally receive smaller conduits, inasmuch as they will outgrow their conduit before degeneration occurs, and should therefore validate the search for alternative short-term substitutes. To extend the use of homografts, Michler and colleagues [10] introduced the surgical downsizing of homografts to bicuspid valved conduits as a valuable shortterm alternative with excellent hemodynamics for neonates and infants in whom outgrowth should be expected. We also successfully applied this inventive technique for RVOT repair in 36 children, when an appropriately sized homograft was not available, before the advent of the bovine xenograft. However, this solution does not address the problem of the overall limited supply of homografts. Some stentless bioprostheses have been used successfully in the aortic position in adults as well as in the pulmonary outflow in infants and children. Despite the obvious advantage of wide and direct availability, the clinical and hemodynamic results remain controversial, with a higher incidence of distal anastomotic narrowing [11, 12]. This phenomenon is especially troublesome in complex RVOT reconstructions when the recipient pulmonary arteries are diminutive and eventually distorted.
540
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
Recently, a bovine jugular vein conduit integrating a natural trileaflet valve has been introduced for clinical application. Animal studies conducted by Ichikawa and associates [3] showed excellent hemodynamic results as well as maintenance of tissue characteristics and lack of degenerative changes after explantation. However, the grafts in those experiments were linked with a different compound from that used with the clinically disposable ones, evoking the eventual effects of fixation technique on endothelial lining and inflammatory response as reported by others [13]. Later, Scavo and coworkers [4] evaluated glutaraldehyde-preserved jugular vein segments, stented in the pulmonary position in dogs, and found equivocal conclusions. The reduced availability of appropriately sized pulmonary homografts prompted us to use this new alternative conduit for RVOT reconstruction in children. Because of the unknown durability, we decided to implant this conduit preferably in infants and younger children in whom outgrowth of the conduit could be expected before hemodynamically significant structural changes should appear. Although we acknowledge that the newly bicuspid homograft is certainly not the standard option for RVOT reconstruction in children, midterm clinical experience with these modified valved conduits has demonstrated that their early hemodynamic performance was equivalent to that of tricuspid, unaltered allografts [14]. Therefore, the preliminary clinical and hemodynamic outcome of the bovine xenografts was compared with that of size-reduced pulmonary homografts, which are considered as an alternative short-term conduit for a similar target population. In this retrospective study, the clinical results were comparable for both types of conduits and were definitely related to the complexity of the underlying disease. No early conduit-related adverse events were noticed, although these data are certainly too precocious for firm conclusions to be drawn. Clinical advantages of this bovine jugular vein conduit are obviously greater shelf availability and the potential of proximal RVOT reconstruction without additional material, which enhances the benefit already offered by the natural continuity between valve and conduit. Besides, the extreme softness and pliability of the jugular vein tissue make implantation and suture line hemostasis extremely convenient, similar to pulmonary homograft use. Regarding the early echocardiographic assessment, the venous valve function is excellent and comparable with that of bicuspid homografts, causing neither residual obstruction nor major regurgitation. However, we noticed significantly more low gradients, located at the distal junction with the pulmonary arteries, in the bicuspid homograft reconstructions, which we believe is promoted by the difference in tissue pliability and wall thickness of an adult-sized homograft implanted on small recipient pulmonary branches. From this viewpoint, the use of bovine jugular vein might be superior to the surgical size reduction of an adult homograft, owing to its gratifying tissue properties. Nevertheless, a few hemodynamically more important distal gradients were
Ann Thorac Surg 2002;74:536 – 41
found in RVOT repairs with a Contegra conduit as well, reflecting the often complex nature of the distal pulmonary outflow in these right-sided heart diseases. These hemodynamic results are, however, concurrent with the early results recently published by Corno and colleagues [15], taking into consideration that their patient population comprised exclusively RVOT reconstructions for Ross procedures in older-aged and larger patients who had a normal pulmonary anatomy. In conclusion, although our study is lacking significant follow-up data, the bovine jugular vein conduit provides a promising substitute for valved reconstruction of the RVOT and compares favorably with downsized pulmonary homografts regarding the early hemodynamic performance and implantation feasibility. However, medium-term results have to be awaited to confirm that this conduit should be a reasonable option for RVOT reconstruction in infants and young children, even when outgrowth of the conduit is expected.
References 1. Ross DN, Somerville J. Correction of pulmonary atresia with a homograft aortic valve. Lancet 1966;2:1446–7. 2. Albert JD, Bishop DA, Fullerton DA, Campbell DN, Clarke DR. Conduit reconstruction of the right ventricular outflow tract: lessons learned in a twelve-year experience. J Thorac Cardiovasc Surg 1993;106:228–36. 3. Ichikawa Y, Noishiki Y, Kosuge T, Yamamoto K, Kondo J, Matsumoto A. Use of bovine jugular vein graft with natural valve for right ventricular outflow tract reconstruction: a one-year animal study. J Thorac Cardiovasc Surg 1997;114: 224–33. 4. Scavo VA, Turrentine MW, Aufiero TX, Sharp TG, Brown JW. Valved bovine jugular venous conduits for right ventricular pulmonary artery reconstruction. ASAIO J 1999;45: 482–7. 5. Bando K, Danielson GK, Schaff HV, et al. Outcome of pulmonary and aortic homografts for right ventricular outflow tract reconstruction. J Thorac Cardiovasc Surg 1995;109: 509–18. 6. Tweddell JS, Pelech AN, Frommelt PC, et al. Factors affecting longevity of homograft valves used in right ventricular outflow tract reconstruction for congenital heart disease. Circulation 2000;102(Suppl 3):III-130 –5. 7. Bielefeld MR, Bishop DA, Campbell DN, Mitchell MB, Grover FL, Clarke DR. Reoperative homograft right ventricular tract reconstruction. Ann Thorac Surg 2001;71:482– 8. 8. 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):365–7. 9. Forbess JM, Shah AS, St. Louis JD, Jaggers JJ, Ungerleider RM. Cryopreserved homografts in the pulmonary position: determinants of durability. Ann Thorac Surg 2001;71:54– 60. 10. Michler RE, Chen JM, Quaegebeur JM. Novel technique for extending the use of allografts in cardiac operations. Ann Thorac Surg 1994;57:83–7. 11. Chard RB, Kang N, Andrews DR, Nunn GR. Use of the Medtronic Freestyle valve as a right ventricular to pulmonary artery conduit. Ann Thorac Surg 2001;71(Suppl):361– 4. 12. 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;71:619–23. 13. Chang Y, Tsai CC, Liang HC, Sung HW. Reconstruction of the right ventricular outflow tract with a bovine jugular vein graft fixed with a naturally occurring crosslinking agent (genipin) in a canine model. J Thorac Cardiovasc Surg 2001; 122:1208–18.
Ann Thorac Surg 2002;74:536 – 41
14. Santini F, Prioli A, Rossetti L, Consolaro G, Mazzucco A. Usefulness of bicuspid homograft reconstruction of the right ventricular outflow tract in infants with complex congenital heart disease. Am J Cardiol 1997;80:1377–9.
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
541
15. Corno AF, Hurni M, Griffin H, Jeanrenaud X, von Segesser LK. Glutaraldehyde-fixed bovine jugular vein as a substitute for the pulmonary valve in the Ross operation. J Thorac Cardiovasc Surg 2001;122:493– 4.
DISCUSSION DR ALI DODGE-KHATAMI (Utrecht, The Netherlands): I have two questions. At the last European meeting, one of the presenters and one of the floor discussants related their experience with Contegra conduits. Both mentioned the appearance of a gelatinous-type material that caused obstruction leading to reoperation. Have you had that type of experience with these conduits? And the second question is, I noticed that you used, in 10 instances of pulmonary atresia with ventricular septal defects, in other words, in children in whom you would expect systemic or suprasystemic right ventricular pressures, the Contegra conduit. Anyone who has used these conduits has noticed how flimsy the valves are inside. Are you more concerned about using the Contegra conduit, rather than a homograft, in children in whom postoperative pulmonary hypertension is expected, or does that not make a difference? Would you expect these conduits to fail or leak more easily in the mid-term follow-up, or not? DR BOVE: Concerning the first question, we never had to reoperate on an infant for dysfunction of a Contegra conduit in the early phase, even when our series has been expanded to more than 70 implants at this time. Concerning your second question, although our follow-up is limited, we have 1 patient presenting a major gradient at the distal level because of small pulmonary arteries, he developed After 6 months, a pulmonary insufficiency grade 2⫹ and might probably increase this regurgitation, eventually requiring surgical relief of the distal obstruction as well as conduit replacement. DR JOHN W. BROWN (Indianapolis, IN): Obviously at Indiana we have had a long interest in the bovine jugular venous valve conduit, having performed much of the experimental work. We started putting these in patients in the United States in May of 1999 and currently have 15 in place. One of the things that I think the audience might be interested in knowing is the relative cost between the bovine jugular venous valve conduit and the homograft. At least in the United States, I think it is going to be less than half price. So if cost has anything to do with your care of patients, that might be important for the audience to understand. My first question relates to the durability of the modified pulmonary homograft. I did downsize a pulmonary homograft before the Contegra conduit was available, and I think it gives satisfactory short-term results. But I would be willing to wager
that within 3 to 5 years the modified pulmonary homograft will shrink to half its original size if it does not have the SG, or SynerGraft, technology. I do not think there is enough clinical data to let us know whether the SynerGraft technology that Cryolife has introduced will make a major difference. What is the length of follow-up on your patients both in the homograft and the Contegra series? Is there a comparison of gradients at the latest follow-up? DR BOVE: Regarding your fist question concerning the price, in Belgium it is not allowed to make a profit from human tissue; however, the price of the Contegra conduit has been made the same as for the homograft. Concerning the second question, I have not included durability results in this study, because the mean follow-up of the Contegra conduits reaches barely 3 months versus 3 years for the bicuspid homograft group. So, it would not be fair to compare these two conduits from this point of view. Concerning the bicuspid pulmonary homografts, we have now data of approximately 5 to 6 years after implantation, and none of these homografts needed explantation until now. However, presently we are using preferably a Contegra conduit for right ventricular outflow tract reconstruction in infants and smaller children in whom outgrowth of the conduit will result in early replacement anyway. DR JOSEPH J. AMATO (Chicago, IL): I wish to congratulate Dr Bove on a fine presentation. My experience is not as great as Dr Brown’s. I have only implanted four of the bovine conduits. The ease of implantation is superb. It is easy to handle and you do not need any augmentation of the proximal hood as we do with a homograft. I rise only to say that at the last European Association of Thoracic Surgery meeting, there was one paper that stated that one of the bovine conduits had been implanted in a child with pulmonary hypertension. That conduit became ectatic and because of dilation of the conduit, it had to be explanted. This has not been my experience, and I have also spoken to Dr Brown, and he has not had a similar experience. So I do not know what the future will be, but I think that this is the substitute conduit of the future in congenital cardiac surgery. Again, I wish to thank you for a fine presentation and excellent results.
Background. Homograft conduits are preferable for right ventricular outflow tract reconstruction in children, but their limited availability remains a major concern. Recently, a valve-containing segment of bovine jugular vein (Contegra, Medtronic Inc, Minneapolis, MN) has been introduced as a potential alternative conduit. Methods. Early clinical and echocardiographic results of right ventricular outflow tract reconstruction were retrospectively compared between 41 children (mean age, 1.9 years), receiving a Contegra conduit and 36 patients (mean age, 2.7 years) with a size-reduced pulmonary homograft. Results. Clinical outcome was comparable with two early deaths in the homograft group and one in the Contegra group. There were no conduit-related complications in either population. Early echocardiographic assessment showed only trivial to mild regurgitation in 9 homografts versus 17 Contegra conduits. The peak gradient across the right ventricular outflow tract conduit
was comparable for both groups, although a larger number of patients, treated with a downsized homograft, had a small gradient at the distal junction with the pulmonary arteries (12 versus 6 patients). None of the patients had a gradient at the valvar level. Conclusions. The valved bovine jugular vein conduit offers a promising substitute for right ventricular outflow tract reconstruction in infants and children, with an early hemodynamic performance that compares favorably with downsized, bicuspid homografts. Clinical advantages are greater shelf availability and the natural continuity between valve and conduit, which allows proximal infundibular shaping without additional material. However, durability must be determined, even though most of these children will require right ventricular outflow tract reoperation after outgrowing the conduit.
T
Subsequent to the encouraging results obtained in animal models [3, 4], a glutaraldehyde-preserved segment of bovine jugular vein, containing a naturally existing trileaflet valve, has been recently introduced into clinical practice. We have used this new graft for RVOT reconstruction in infants and young children, and we report their preliminary clinical and hemodynamic performance compared with size-reduced, bicuspid pulmonary homografts, which we used previously in the absence of an available, appropriate-sized homograft.
he successful use of a valved homograft conduit for right ventricular outflow tract (RVOT) reconstruction, first described by Ross and Sommerville [1] in 1966, has significantly widened the feasibility of repair of various right-sided congenital heart diseases. Additionally, the growing popularity of the Ross procedure to treat aortic valve disease has implied more frequently the need for RVOT reconstruction. Both techniques have resulted in an increasing demand for homografts, pulmonary ones in particular, because of their superior durability and convenience in the pulmonary circulation [2]. However, despite continuous refinements in preservation and storage techniques, availability remains a limiting factor in the extensive clinical application of homografts, especially for the small-sized grafts required for neonatal and infant recipients, creating a need for alternative conduits.
Presented at the Thirty-eighth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28 –30, 2002. Address reprint requests to Dr Bove´ , Department of Cardiac Surgery, U.Z. Gent, De Pintelaan 185 5K12, 9000 Gent, Belgium; e-mail: [email protected].
© 2002 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
(Ann Thorac Surg 2002;74:536 – 41) © 2002 by The Society of Thoracic Surgeons
Patients and Methods Patients From May 2000 to June 2001, 41 children (29 boys, 12 girls) with a mean age of 1.9 ⫾ 2.6 years (range, 7 days to 13 years) and a mean weight of 8.4 ⫾ 4.4 kg (range, 2.8 to 18 kg) underwent RVOT reconstruction using a valved bovine jugular vein conduit (Contegra group; Medtronic Inc., Minneapolis, MN). This patient population was compared with 36 patients (18 boys, 18 girls), operated on between March 1996 and November 2000, who received a surgically downsized, bicuspid pulmonary homograft 0003-4975/02/$22.00 PII S0003-4975(02)03728-1 21
Table 1. Indication for Right Ventricular Outflow Tract Reconstruction Indication Tetralogy of Fallot PA-VSD Truncus arteriosus TGA-VSD-PS DORV-PS AV/VA discordance-VSD-PS Pulmonary valve stenosis PA-intact septum Ross procedure Total
537
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
Ann Thorac Surg 2002;74:536 – 41
Homograft
Contegra
5 7 7 5 3 2 1 ... 6 36
16 10 5 3 1 ... ... 1 5 41
AV/VA discordance-VSD-PS ⫽ atrioventricular-ventriculoarterial discordance with ventricular septal defect and pulmonary stenosis; DORVPS ⫽ double-outlet right ventricle with pulmonary stenosis; PA-intact septum ⫽ pulmonary atresia with intact ventricular septum; PAVSD ⫽ pulmonary atresia with ventricular septal defect; TGA-VSDPS ⫽ transposition great arteries with ventricular septal defect and pulmonary stenosis.
(HG group) when an appropriately sized conduit was not available in that period. Their mean age was 2.7 ⫾ 2.5 years (range, 6 days to 10 years) and mean weight 10.3 ⫾ 5.1 kg (range, 2.5 to 23 kg). Nine (25%) and 20 (45%) patients younger than 1 year of age (p ⫽ 0.03) were in the HG and Contegra groups, respectively. The primary diagnoses indicating RVOT reconstruction are listed in Table 1. Several patients in both groups had a previous surgical palliation (7 HG versus 8 Contegra patients; p ⫽ 0.85) or an interventional procedure such as aortic and pulmonary valve dilation and embolization of aortopulmonary collaterals (4 HG versus 8 Contegra patients; p ⫽ 0.31). Nine patients underwent a primary correction of their original disease and required the implantation of a valved conduit for early failure of transannular patch repair of tetralogy of Fallot (2 HG; 2 Contegra), structural degeneration of a first homograft (3 HG; 1 Contegra), and recurrent obstruction after infundibular enlargement (1 HG; 0 Contegra). Pulmonary arterial hypertension was present in 11 (31%) patients in the HG group and 6 (15%) patients in the Contegra group (p ⫽ 0.09), and was mainly related to pathologic processes such as truncus arteriosus and pulmonary atresia with ventricular septal defect and aortopulmonary collateral lung perfusion.
Operative Technique All procedures were performed with conventional cardiopulmonary bypass, moderate to deep hypothermia, and cold crystalloid cardioplegia. Deep hypothermic circulatory arrest was needed in 2 patients, who required simultaneous repair of aortic arch anomalies (1 interrupted aortic arch and 1 coarctation). The bovine jugular vein graft was procured as a 12- to 14-cm-long tubular conduit, containing a valve of three semilunar leaflets in its middle third, with a diameter varying from 12 to 22 mm. Despite glutaraldehyde fixa-
tion, the tissue has maintained a remarkable pliability and softness, offering optimal suturing and tailoring characteristics for congenital RVOT repair. Surgical transformation of an adult-sized pulmonary homograft into a bicuspid conduit was achieved by excision of one longitudinal third, containing a cusp, and closure of the newly formed bicuspid conduit by a continuous running suture. Implantation of the downsized conduit as well as the Contegra conduit was performed, respecting the same principles of conduit insertion for RVOT reconstruction: (1) placement of the conduit away from the midline to avoid sternal compression, (2) positioning of the valve as distal as possible, and (3) proximal RVOT enlargement with additional autologous pericardium when a bicuspid homograft was used and using the natural tubular extension of the vein segment for the bovine xenograft. The internal diameter of the implanted size-reduced homografts ranged from 10 to 20 mm, and from 12 to 20 mm for the Contegra conduits. The median size of the selected conduit was 16 mm for both types. Concomitant operative procedures are listed in Table 2. Mean aortic cross-clamp time and cardiopulmonary bypass time were comparable, respectively 65.4 ⫾ 38.2 minutes and 145.1 ⫾ 48.9 minutes in the HG group and 60.5 ⫾ 22.3 minutes and 137.0 ⫾ 32.3 minutes in the Contegra group. The mean right ventricular to left ventricular pressure ratio before sternal closure was 0.53 ⫾ 0.09 in the HG group and 0.53 ⫾ 0.16 in the Contegra group.
Echocardiographic Assessment Transthoracic two-dimensional echocardiography was performed with a 3.5- or 5.0-MHz transducer with a Hewlett-Packard Sonos 5000 Ultrasound system. Early in-hospital evaluation was compared in both types of RVOT reconstruction with particular attention to valve
Table 2. Procedures Associated With Right Ventricular Outflow Tract Reconstruction Homograft BT shunt ligation VSD enlargement PA plasty ASD closure IAA repair Atrial/Arterial Switch Coarctation repair APCA ligation
14 patients
Contegra
16 patients
6 2
BT shunt ligation ASD closure
5 6
2 2 1
PA plasty PAPVR repair RVOT aneurysm resection APCA ligation
4 1 1
1
1
1 2
APCA ⫽ aortopulmonary collateral artery; ASD ⫽ atrial septal defect; BT shunt ⫽ Blalock-Taussing shunt; IAA ⫽ interrupted aortic arch; PA plasty ⫽ pulmonary artery plasty; PAPVR ⫽ partial anomalous pulmonary venous return; RVOT ⫽ right ventricular outflow tract; VSD ⫽ ventricular septal defect.
538
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
Ann Thorac Surg 2002;74:536 – 41
Table 3. Complications Complication Cardiac Low cardiac output ECMO Pulmonary hypertension AV block Pulmonary Neurologic Seizures Hypoxic encephalopathy Renal failure Early reoperation Bleeding VSD enlargement Residual VSD Bidirectional Glenn shunt
Homograft
Contegra
10 (28%) 5 2 5 2 11 (31%) 2 (6%) 1 1 1 (3%) 3 (8%) 1 1 1 ...
8 (20%) 6 2 3 ... 9 (22%) 2 (5%) 1 1 2 (5%) 4 (10%) 2 ... 1 1
AV block ⫽ atrioventricular block; ECMO ⫽ extracorporeal membrane oxygenation; VSD ⫽ ventricular septal defect.
function and presence as location of eventual residual outflow obstruction. The peak gradients were classified as subvalvular, valvular, or distal postvalvular obstruction according to their site, and divided into four groups according to the severity of the gradient: no gradient, a minor gradient less than 15 mm Hg, a gradient between 15 and 30 mm Hg, and a gradient of more than 30 mm Hg.
Statistical Analysis Data are expressed as mean ⫾ standard deviation value or as median value and the range. Variables were compared using the 2 method or Fisher’s exact test. A p value less than 0.05 was considered significant. All statistical analyses were conducted with the StatView 5.0 system (SAS Institute, Cary, NC).
Noteworthy is that 3 children necessitated adjunctive ventricular assistance by extracorporeal membrane oxygenation for refractory right ventricular dysfunction in cases of late referral of tetralogy of Fallot, all of whom survived. Ventilation time, inotropic support duration, and intensive care and hospital stay were, respectively, for the HG and Contegra groups 4.8 ⫾ 7.3 days and 4.1 ⫾ 4.8 days, 4.6 ⫾ 4.7 days and 5.5 ⫾ 5.7 days, 9.9 ⫾ 13.4 days and 8.2 ⫾ 6.2 days, and 17.7 ⫾ 17.4 days and 16.9 ⫾ 8.6 days. These data were not significantly different and independent of the implanted conduit type. All surviving patients showed a remarkable improvement of their functional status and were discharged in New York Heart Association class I or II.
Echocardiographic Outcome The last echocardiographic data, recorded before hospital discharge, showed a competent valve function in the majority of the patients in both groups: 27 (75%) of the HG patients versus 23 (59%) of the Contegra patients (p ⫽ 0.13). Trivial to mild valve leakage was found in 9 patients with a bicuspid homograft, and quantified as grade I regurgitation in 8 patients and grade II in 1 patient. Fifteen children with a Contegra conduit had a grade I valve insufficiency and 2 had a grade II leakage (Fig 1). This difference was not significant (p ⫽ 0.13). There was no specific correlation between valve incompetence and residual pulmonary hypertension. However, regurgitation coincided with some residual distal RVOT obstruction in 5 of the 9 HG patients, and in 4 of the 15 Contegra patients. Regarding the presence of a residual gradient across the reconstructed RVOT, the majority of patients in both groups had no outflow obstruction, ie, 24 (67%) HG patients and 31 (77.5%) Contegra patients (p ⫽ 0.29). In a
Results Clinical Outcome Two patients (6%) died early in the HG group. The first was operated on at the age of 1 week, presenting truncus arteriosus and interrupted aortic arch, and died of persistent pulmonary hypertension, low cardiac output, and acute renal failure. The second underwent a one-stage repair of double-outlet right ventricle with pulmonary stenosis and aortic coarctation under deep hypothermic circulatory arrest, at the age of 8 months. He died on the 12th postoperative day of severe right ventricular failure and atrioventricular block. In the Contegra group 1 patient (2%) died perioperatively after truncus arteriosus repair at the age of 2.5 years, because of intractable pulmonary hypertension (right ventricular to left ventricular pressure ratio ⫽ 1). Regarding overall morbidity, there was no statistically significant difference between the two groups: 18 (50%) patients in the HG group versus 16 (39%) patients in the Contegra group (p ⫽ 0.33). The complications are depicted in Table 3.
Fig 1. Regurgitation distribution. Numbers of patients according to grade of valve insufficiency are shown for the two types of conduits. (HG ⫽ homograft.)
Ann Thorac Surg 2002;74:536 – 41
significantly different number of patients a small gradient of 10 to 15 mm Hg was found in the HG group compared with the Contegra population (9 versus 0 patients; p ⫽ 0.007), and all these peak gradients were measured at the distal anastomotic site. A moderate distal gradient of 15 to 30 mm Hg was present in 3 HG patients versus 4 Contegra patients. A more severe gradient exceeding 30 mm Hg was found at the subvalvular or the distal level in 2 patients in whom RVOT repair was performed with a jugular vein segment. Considering the site of the measured obstruction, most gradients were localized at the distal junction between conduit and recipient pulmonary arteries, ie, 12 patients in the HG group versus 6 patients in the Contegra group (p ⫽ 0.05). This included the cases in which a separate enlarging plasty of the pulmonary branches was achieved: 2 of the 12 HG patients versus 3 of the 6 Contegra patients. Additionally, most of these residual distal obstructions occurred in pathologic processes including pulmonary arborization anomalies such as pulmonary atresia and tetralogy of Fallot: 8 of the 12 in the HG group and 6 of the 6 in the Contegra group. None of the RVOT corrections as part of the Ross procedure, either by a bicuspid homograft or a jugular vein xenograft, showed a residual outflow obstruction. Three patients in the Contegra group had an insufficient relief of the subvalvular hypertrophied infundibulum, with residual gradients of 15, 25, and 30 mm Hg. Finally, no gradient was measured at the valvar level in either of the conduit types. Figure 2 illustrates the distribution and grade of the peak gradients.
Comment Since the successful application of cryopreservation in the mid-1980s, several studies have advocated the use of cryopreserved pulmonary homografts as the conduit of choice for reconstruction of the RVOT [2, 5, 6]. However, the expanding indications for repair of various congenital as well as acquired heart diseases have led to an increasing mismatch between demand and supply, and made availability a limiting factor for the use of homografts, mostly in the smaller sizes for neonatal and infant operations. Moreover, despite better understanding of immunohistologic interactions and refinements of preservation, progressive structural degeneration and outgrowth determined significantly young recipient age and implantation of small-size conduits as risk factors for early homograft failure [6]. Recent long-term analysis of homograft durability revealed that conduits sized smaller than 15 mm usually required earlier explantation [7]. Lange and coworkers [8] found, in a comparative study between allografts and xenograft conduits, that children receiving a conduit smaller or equal to 15 mm commonly needed reoperation within 6 years after implantation because of outgrowth, and concluded that a xenograft might be a justified option in neonates and infants. Also Forbess and associates [9] showed an equivalent shortterm outcome of aortic and pulmonary homografts in
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
539
Fig 2. (A) Grade of obstructive gradient. Numbers of patients according to peak gradient are shown for the two conduits. (B) Level of obstructive gradient. Numbers of patients according to location of the obstruction are shown for the two conduits.
younger patients. These findings should support the speculation that durability and even type of the implanted conduit for RVOT reconstruction should be a less critical issue in younger children who generally receive smaller conduits, inasmuch as they will outgrow their conduit before degeneration occurs, and should therefore validate the search for alternative short-term substitutes. To extend the use of homografts, Michler and colleagues [10] introduced the surgical downsizing of homografts to bicuspid valved conduits as a valuable shortterm alternative with excellent hemodynamics for neonates and infants in whom outgrowth should be expected. We also successfully applied this inventive technique for RVOT repair in 36 children, when an appropriately sized homograft was not available, before the advent of the bovine xenograft. However, this solution does not address the problem of the overall limited supply of homografts. Some stentless bioprostheses have been used successfully in the aortic position in adults as well as in the pulmonary outflow in infants and children. Despite the obvious advantage of wide and direct availability, the clinical and hemodynamic results remain controversial, with a higher incidence of distal anastomotic narrowing [11, 12]. This phenomenon is especially troublesome in complex RVOT reconstructions when the recipient pulmonary arteries are diminutive and eventually distorted.
540
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
Recently, a bovine jugular vein conduit integrating a natural trileaflet valve has been introduced for clinical application. Animal studies conducted by Ichikawa and associates [3] showed excellent hemodynamic results as well as maintenance of tissue characteristics and lack of degenerative changes after explantation. However, the grafts in those experiments were linked with a different compound from that used with the clinically disposable ones, evoking the eventual effects of fixation technique on endothelial lining and inflammatory response as reported by others [13]. Later, Scavo and coworkers [4] evaluated glutaraldehyde-preserved jugular vein segments, stented in the pulmonary position in dogs, and found equivocal conclusions. The reduced availability of appropriately sized pulmonary homografts prompted us to use this new alternative conduit for RVOT reconstruction in children. Because of the unknown durability, we decided to implant this conduit preferably in infants and younger children in whom outgrowth of the conduit could be expected before hemodynamically significant structural changes should appear. Although we acknowledge that the newly bicuspid homograft is certainly not the standard option for RVOT reconstruction in children, midterm clinical experience with these modified valved conduits has demonstrated that their early hemodynamic performance was equivalent to that of tricuspid, unaltered allografts [14]. Therefore, the preliminary clinical and hemodynamic outcome of the bovine xenografts was compared with that of size-reduced pulmonary homografts, which are considered as an alternative short-term conduit for a similar target population. In this retrospective study, the clinical results were comparable for both types of conduits and were definitely related to the complexity of the underlying disease. No early conduit-related adverse events were noticed, although these data are certainly too precocious for firm conclusions to be drawn. Clinical advantages of this bovine jugular vein conduit are obviously greater shelf availability and the potential of proximal RVOT reconstruction without additional material, which enhances the benefit already offered by the natural continuity between valve and conduit. Besides, the extreme softness and pliability of the jugular vein tissue make implantation and suture line hemostasis extremely convenient, similar to pulmonary homograft use. Regarding the early echocardiographic assessment, the venous valve function is excellent and comparable with that of bicuspid homografts, causing neither residual obstruction nor major regurgitation. However, we noticed significantly more low gradients, located at the distal junction with the pulmonary arteries, in the bicuspid homograft reconstructions, which we believe is promoted by the difference in tissue pliability and wall thickness of an adult-sized homograft implanted on small recipient pulmonary branches. From this viewpoint, the use of bovine jugular vein might be superior to the surgical size reduction of an adult homograft, owing to its gratifying tissue properties. Nevertheless, a few hemodynamically more important distal gradients were
Ann Thorac Surg 2002;74:536 – 41
found in RVOT repairs with a Contegra conduit as well, reflecting the often complex nature of the distal pulmonary outflow in these right-sided heart diseases. These hemodynamic results are, however, concurrent with the early results recently published by Corno and colleagues [15], taking into consideration that their patient population comprised exclusively RVOT reconstructions for Ross procedures in older-aged and larger patients who had a normal pulmonary anatomy. In conclusion, although our study is lacking significant follow-up data, the bovine jugular vein conduit provides a promising substitute for valved reconstruction of the RVOT and compares favorably with downsized pulmonary homografts regarding the early hemodynamic performance and implantation feasibility. However, medium-term results have to be awaited to confirm that this conduit should be a reasonable option for RVOT reconstruction in infants and young children, even when outgrowth of the conduit is expected.
References 1. Ross DN, Somerville J. Correction of pulmonary atresia with a homograft aortic valve. Lancet 1966;2:1446–7. 2. Albert JD, Bishop DA, Fullerton DA, Campbell DN, Clarke DR. Conduit reconstruction of the right ventricular outflow tract: lessons learned in a twelve-year experience. J Thorac Cardiovasc Surg 1993;106:228–36. 3. Ichikawa Y, Noishiki Y, Kosuge T, Yamamoto K, Kondo J, Matsumoto A. Use of bovine jugular vein graft with natural valve for right ventricular outflow tract reconstruction: a one-year animal study. J Thorac Cardiovasc Surg 1997;114: 224–33. 4. Scavo VA, Turrentine MW, Aufiero TX, Sharp TG, Brown JW. Valved bovine jugular venous conduits for right ventricular pulmonary artery reconstruction. ASAIO J 1999;45: 482–7. 5. Bando K, Danielson GK, Schaff HV, et al. Outcome of pulmonary and aortic homografts for right ventricular outflow tract reconstruction. J Thorac Cardiovasc Surg 1995;109: 509–18. 6. Tweddell JS, Pelech AN, Frommelt PC, et al. Factors affecting longevity of homograft valves used in right ventricular outflow tract reconstruction for congenital heart disease. Circulation 2000;102(Suppl 3):III-130 –5. 7. Bielefeld MR, Bishop DA, Campbell DN, Mitchell MB, Grover FL, Clarke DR. Reoperative homograft right ventricular tract reconstruction. Ann Thorac Surg 2001;71:482– 8. 8. 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):365–7. 9. Forbess JM, Shah AS, St. Louis JD, Jaggers JJ, Ungerleider RM. Cryopreserved homografts in the pulmonary position: determinants of durability. Ann Thorac Surg 2001;71:54– 60. 10. Michler RE, Chen JM, Quaegebeur JM. Novel technique for extending the use of allografts in cardiac operations. Ann Thorac Surg 1994;57:83–7. 11. Chard RB, Kang N, Andrews DR, Nunn GR. Use of the Medtronic Freestyle valve as a right ventricular to pulmonary artery conduit. Ann Thorac Surg 2001;71(Suppl):361– 4. 12. 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;71:619–23. 13. Chang Y, Tsai CC, Liang HC, Sung HW. Reconstruction of the right ventricular outflow tract with a bovine jugular vein graft fixed with a naturally occurring crosslinking agent (genipin) in a canine model. J Thorac Cardiovasc Surg 2001; 122:1208–18.
Ann Thorac Surg 2002;74:536 – 41
14. Santini F, Prioli A, Rossetti L, Consolaro G, Mazzucco A. Usefulness of bicuspid homograft reconstruction of the right ventricular outflow tract in infants with complex congenital heart disease. Am J Cardiol 1997;80:1377–9.
BOVE´ ET AL BOVINE JUGULAR VEIN CONDUIT
541
15. Corno AF, Hurni M, Griffin H, Jeanrenaud X, von Segesser LK. Glutaraldehyde-fixed bovine jugular vein as a substitute for the pulmonary valve in the Ross operation. J Thorac Cardiovasc Surg 2001;122:493– 4.
DISCUSSION DR ALI DODGE-KHATAMI (Utrecht, The Netherlands): I have two questions. At the last European meeting, one of the presenters and one of the floor discussants related their experience with Contegra conduits. Both mentioned the appearance of a gelatinous-type material that caused obstruction leading to reoperation. Have you had that type of experience with these conduits? And the second question is, I noticed that you used, in 10 instances of pulmonary atresia with ventricular septal defects, in other words, in children in whom you would expect systemic or suprasystemic right ventricular pressures, the Contegra conduit. Anyone who has used these conduits has noticed how flimsy the valves are inside. Are you more concerned about using the Contegra conduit, rather than a homograft, in children in whom postoperative pulmonary hypertension is expected, or does that not make a difference? Would you expect these conduits to fail or leak more easily in the mid-term follow-up, or not? DR BOVE: Concerning the first question, we never had to reoperate on an infant for dysfunction of a Contegra conduit in the early phase, even when our series has been expanded to more than 70 implants at this time. Concerning your second question, although our follow-up is limited, we have 1 patient presenting a major gradient at the distal level because of small pulmonary arteries, he developed After 6 months, a pulmonary insufficiency grade 2⫹ and might probably increase this regurgitation, eventually requiring surgical relief of the distal obstruction as well as conduit replacement. DR JOHN W. BROWN (Indianapolis, IN): Obviously at Indiana we have had a long interest in the bovine jugular venous valve conduit, having performed much of the experimental work. We started putting these in patients in the United States in May of 1999 and currently have 15 in place. One of the things that I think the audience might be interested in knowing is the relative cost between the bovine jugular venous valve conduit and the homograft. At least in the United States, I think it is going to be less than half price. So if cost has anything to do with your care of patients, that might be important for the audience to understand. My first question relates to the durability of the modified pulmonary homograft. I did downsize a pulmonary homograft before the Contegra conduit was available, and I think it gives satisfactory short-term results. But I would be willing to wager
that within 3 to 5 years the modified pulmonary homograft will shrink to half its original size if it does not have the SG, or SynerGraft, technology. I do not think there is enough clinical data to let us know whether the SynerGraft technology that Cryolife has introduced will make a major difference. What is the length of follow-up on your patients both in the homograft and the Contegra series? Is there a comparison of gradients at the latest follow-up? DR BOVE: Regarding your fist question concerning the price, in Belgium it is not allowed to make a profit from human tissue; however, the price of the Contegra conduit has been made the same as for the homograft. Concerning the second question, I have not included durability results in this study, because the mean follow-up of the Contegra conduits reaches barely 3 months versus 3 years for the bicuspid homograft group. So, it would not be fair to compare these two conduits from this point of view. Concerning the bicuspid pulmonary homografts, we have now data of approximately 5 to 6 years after implantation, and none of these homografts needed explantation until now. However, presently we are using preferably a Contegra conduit for right ventricular outflow tract reconstruction in infants and smaller children in whom outgrowth of the conduit will result in early replacement anyway. DR JOSEPH J. AMATO (Chicago, IL): I wish to congratulate Dr Bove on a fine presentation. My experience is not as great as Dr Brown’s. I have only implanted four of the bovine conduits. The ease of implantation is superb. It is easy to handle and you do not need any augmentation of the proximal hood as we do with a homograft. I rise only to say that at the last European Association of Thoracic Surgery meeting, there was one paper that stated that one of the bovine conduits had been implanted in a child with pulmonary hypertension. That conduit became ectatic and because of dilation of the conduit, it had to be explanted. This has not been my experience, and I have also spoken to Dr Brown, and he has not had a similar experience. So I do not know what the future will be, but I think that this is the substitute conduit of the future in congenital cardiac surgery. Again, I wish to thank you for a fine presentation and excellent results.