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Eur J Cardiothorac Surg 2002;21:703-710
© 2002 Elsevier Science NL

Bovine valved venous xenografts for RVOT reconstruction: results after 71 implantations

Thomas Breymanna*, Wolf-Ruediger Thiesb, Dietmar Boethiga, Rainer Goergb, Ute Blanza, Reiner Koerfera

a Department of Thoracic and Cardiovascular Surgery, Heart-Center North-Rhine Westfalia, Ruhr University of Bochum, Bad Oeynhausen, Germany
b Department of Pediatric Cardiology, Heart-Center North-Rhine Westfalia, Ruhr University of Bochum, Bad Oeynhausen, Germany

Received 18 September 2001; received in revised form 6 December 2001; accepted 14 January 2002.

* Corresponding author. Tel.: +49-5731-971912; fax: +49-5731-972020
e-mail: tbreymann{at}hdz-nrw.de


    Abstract
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 
Background: Pediatric right ventricular outflow tract (RVOT) reconstruction with homo- or porcine xenografts is problematic because of limited availability, lack of material for reconstruction, early degeneration, and tissue ingrowth. Contegra®, a bovine jugular vein graft, might be an interesting alternative to overcome these problems. Patients and methods: Within a Federal Drug Administration controlled study, we implanted 71 Contegra® pulmonary valved conduits from May 1999 to September 2001 in 71 patients (male/female 33/38) in the age range 2 days–17.4 years, median 1.2 years. Twenty five were primary repairs, 22 had previous graft implantations, and 24 had other repairs/palliations. Preoperative diagnoses: truncus arteriosus communis (19 patients), tetralogy of Fallot (32), double outlet right ventricle (13), transposition of the great arteries (5), and two rare complex malformations. The size of implanted Contegra® conduits ranged from 12 to 22 mm. Echocardiography was performed at 1 and 3 months, and then every 3 months postoperatively. Follow-up time was 27 months (maximal), 80 years in total. Results were compared with our 52 homograft- and 30 Tissuemed® porcine xenograft recipients. Results: Contegra® enables the surgeon to perform all anastomoses without additional material. Its tissue is very apt for suturing and its insufficiencies are common, but without clinical significance or tendency to increase. We saw no sign of conduit or valve degeneration during the whole follow-up up to 27 months. There were no device related adverse events. Redos: five for peripheral pulmonary arteries, two residual ventricular septum defect (VSD) closures. There were six deaths (five early, one late). The maximal transvalvular gradients of 25–42 mmHg were measured in seven patients; these gradients did not increase further during the follow-up. Six patients with completely intact Contegra® conduits developed pressure gradients of more than 70 mmHg immediately distal from the conduit. At 27 months, Contegra® grafts were advantageous compared to homografts with respect to survival and freedom from explantation. Right ventricle to left ventricle (RV/LV) ratio development and freedom from explantation/redo were equal for Contegra® conduits and homografts. Porcine Tissuemed® xenografts were significantly inferior. Conclusion: The Contegra® conduit offers unique tailoring and suturing options for primary and redo RVOT reconstruction. At 27 months, its durability seems at least equivalent to homografts and is superior to porcine Tissuemed® xenografts.

Key Words: Pulmonary valved conduit • Contegra® bovine jugular vein graft • Homograft • Xenograft • Right ventricular outflow tract reconstruction


    1. Introduction
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 
A variety of congenital anomalies with severe right ventricular outflow tract (RVOT) obstruction or RVOT interruption requires surgical reconstruction from the infundibulum up to the pulmonary artery bifurcation or even into the branches of the pulmonary arteries. Different techniques, such as implantation of bioprostheses fixed in woven Dacron tubes as supportive housing, glutaraldehyde fixed porcine or bovine pericardial valves, glutaraldehyde fixed porcine aortic or pulmonary roots, non-valved conduits, homografts or valvuloplasties are used to reconstruct the continuity between the right ventricle and the pulmonary arteries. Homografts – although not ideal – have a satisfactory performance despite occasional pannus formation within the conduit wall and increasing incompetence/calcification, but there is lack of sufficient availability [15].

Porcine xenografts perform worse than homografts with respect to all durability parameters such as early calcification and stenosis of the valve, incompetence, pannus and graft tissue stiffness [68].

To overcome these limitations, the Contegra® conduit, a totally integrated valved conduit, has been developed. It consists of a bovine jugular vein with a naturally integrated valve in it. Only venous valves consisting of three leaflets with natural sinuses are made available for clinical purposes. Abundant material on both sides of the valve allows enhanced implantation techniques. The Contegra® conduit is treated by a buffered low pressure glutaraldehyde fixation. No additional anticalcification treatment is used. The conduits are available in sizes from 12 to 22 mm. They are also available with rings as reinforcement. We used only the ringless conduits because we consider pliability as one of the big advantages of this material. The Medtronic product is CE-certified. In the USA, a clinical trial aimed at the approval of Federal Drug Administration (FDA) is in progress. Due to shortage of small homografts for infants and after disappointing experiences with porcine aortic xenografts at our institution, we decided in May 1999 to implant the Contegra® bovine valved conduit within a controlled study. The study included only patients requiring an RVOT reconstruction. This report presents the results of our first 71 Contegra® conduits implanted in pediatric patients and compares them with the results of our homograft and porcine Tissuemed® aortic xenograft conduit implantations.


    2. Patients and methods
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 
2.1. Contegra® patient population
Within an FDA-controlled multicentre study (extended phase I study) approved by the local ethics committee, we implanted 71 Contegra® conduits in 71 patients, who were newborn to young adults, from May 1999 to September 2001. Only patients with cardiovascular malformations requiring RVOT reconstruction were included. Table 1 shows the demographic data and diagnoses of the operated patients. Median age was 1.2 years and median weight was 9.4 kg. Tetralogy of Fallot (TOF) with severe hypoplasia or atresia of the pulmonary root, often associated with hypoplasia of the pulmonary arteries or TOF with absent pulmonary valve syndrome formed the most common group (44%). It was followed by truncus arteriosus communis (TAC, 27%), double outlet right ventricle (DORV, 19%), and various forms of transposition of the great arteries (TGA, 7%) with obstructed pulmonary arterial flow. Follow-up was 100% complete.


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Table 1. Description of the study cohorts

 
2.2. Homograft and xenograft cohorts
The cohort of patients with a Contegra® graft (n=71) was compared with our patients who had undergone RVOT reconstruction with a homograft (n=52) or with a Tissuemed® porcine xenograft (n=30). The three patient cohorts were operated chronologically one after the other starting with the homograft cohort; they were essentially comparable with regard to diseases, age and status (Table 1). All homografts have been harvested, prepared and cryopreserved at our institution from explanted hearts of patients who had undergone heart transplantation at our institution. All Contegra® conduits, homografts, and porcine xenografts were implanted by the same surgeon. Indications for implanting valved conduits did not change over time.

Conduits of 12, 14, 16, 18, 20, and 22 mm were implanted in 30, 12, seven, five, eight, and nine patients, respectively. The majority of the conduits were 12 and 14 mm in diameter. No ring-reinforced conduit was implanted.

2.3. Statistical analysis
Statistical analysis was performed with SPSS 10.0 (SPSS Inc., Chicago). Means are given with 95% confidence intervals of their mean value or standard deviation, as indicated. Survival and event-free time estimates were calculated with the Kaplan–Meier method and compared by log rank test. P values of <0.05 were considered significant. Linear regression was used to estimate the relationship between RV/LV ratio and the degree of Contegra® incompetence. Early death was defined as death within 30 days after the operation.

2.4. Echo examinations
The patients were examined before discharge and every 3 months postoperatively and the examination included a standardised colour Doppler examination at each interval. We determined separate gradients: (a) at valve level, measured with pulsed wave (PW) Doppler, (b) at distal of the valve, measured with continuous wave (CW) Doppler, calculated with the simplified Bernoulli equation Vpa2x4 for gradients <15 mmHg and with the complete Bernoulli equation (Vpa2-Vv2)x4 for higher gradients, where Vpa is the CW Doppler-measured velocity over the whole RVOT and Vv the PW Doppler-measured velocity at conduit valve level.

2.5. Surgical techniques
Surgical technique varied according to the different initial situation.

2.5.1. Primary repair (25 patients)
Some of the most complex malformations have been operated under circulatory arrest while others have been operated in low flow and myocardial protection by crystalloid cardioplegia (Bretschneider). A major attempt has been made to locate the conduit valve as close as possible to the native pulmonary bifurcation to avoid squeezing and distortion of the valve by closure of the sternum. In addition, this made it easier to implant the high profile type venous valve. We tried to position the conduit in such a way as to avoid conduit laceration at the next sternotomy (for conduit replacement). The connection to the subpulmonary ventricle was easily done by a simple running suture using the proximal tubular extension of the conduit without the need of any additional homologous or foreign material. The conduit was cut down in all cases in a S-shaped manner to fit against the ventriculotomy. In four patients with pulmonary atresia, VSD and MAPCAs, primary repair was performed by a median sternotomy. In those patients, the distal part of the conduit was extensively used to augment the central part of the reconstructed pulmonary arteries. The conduit was incised longitudinally from the distal end to the level of the commissures of the conduit valve. Then two flaps were tailored to be long enough to reach both lung hili. Due to the great elasticity of this new material, there was no kinking.

2.5.2. Conduit replacement (22 patients)
Patients of this group were revised in mild hypothermia after singular venous atrial cannulation, regardless to the underlying disease (5xTOF, 8xDORV, 4xTAC, 1xTGA+VSD+PS).

If necessary, a right pulmonary artery plasty was carried out in short intermittent aortic cross clamping and aortic transsection. In all other cases, the operation was performed without myocardial ischemia but ventricular fibrillation or beating heart. The degenerated homografts (n=8), porcine xenografts (n=11) or Dacron tubes (n=3) were entirely removed. The continuity between RVOT and pulmonary arteries was then achieved by a Contegra® conduit as described above.

Additional foreign material was never needed. We found that Contegra® conduits simplified the procedure very much.

2.5.3. Failed repairs
Twenty-four patients with previous palliations or repairs had to be reoperated: 17 RVOT patches (11 transannular, six not transannular), five aortopulmonary shunts; two patients with a Taussig Bing malformation and previous Kawashima procedures. The operative method is like the one used for conduit replacement.


    3. Results
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 
Follow-up was 100% complete. Mean follow-up was 1.2 years (2 weeks to 27 months), in a total of 80 patient years.

3.1. Device related adverse events
During the whole follow-up, there occurred no device-specific complication like calcification or degeneration of the conduit tubes or valves. The reasons for reoperation or death were related to the underlying disease in each case. The Contegra® graft itself was never the reason of any adverse event.

3.2. Mortality
There were five early (7%) and one late death. The reason for early death was postoperative myocardial failure in three cases (two TAC IV (pulmonary atresia+VSD+MAPCAs), one with a weight of 2.4 kg with a very rare complex malformation), one sepsis, one intractable junctional tachycardia. A further patient with TOF and absent pulmonary valve syndrome died 6 months postoperatively due to pulmonary artery ectasia, repeated bronchial obstructive crises, and chronic infection. Echocardiographic assessment demonstrated perfect conduit function and technical correctness of the performed procedures in each case.

3.3. Reoperations
There were seven reoperations. Within the primarily repaired group, two residual VSDs had to be reoperated after 8 weeks and 4 months, respectively. Three patients with repaired TAC A2 and one with repaired TOF developed restenoses at the origin of the pulmonary branch arteries after 1, 2, 4, and 12 months with pressure gradients of more than 80 mmHg. They underwent plastic augmentation. One of the patients with TOF and absent pulmonary valve underwent a reduction plasty of the right pulmonary artery 2 months after repair. The ectatic right pulmonary artery was considered to compress the right main bronchus significantly. She was the one who died late. In each case, inspection of the conduit revealed a pliable, non-calcified tissue and the valve itself appeared morphologically as newly implanted.

3.4. Echocardiographic analyses of the Contegra® conduit function
3.4.1. Pulmonary artery stenosis
During the whole follow-up, there was no pressure gradient detectable across the conduit valve in 35 patients (49%). The maximal transvalvular peak gradients of 25–32 mmHg were measured in seven patients (10%); these gradients showed no tendency to increase over time (Fig. 1 ).



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Fig. 1. Transvalvular and pulmonary artery bifurcation gradients over time. In this figure (and following ones), we summarised results of all patients and all echo examinations. The mean transvalvular gradients remain constant over time; at bifurcation level, however, the mean gradient course indicates the problem of hypoplastic PA branches.

 
At the origin of the pulmonary branch arteries, maximal pressure gradients (in any of the follow-up examinations) up to 30 mmHg (pulmonary artery, PA, gradient) were detectable in 27 patients (38%), between 30 and 70 mmHg in 28 patients (39%), and gradients of more than 70 mmHg were found in six patients (8%). Four of the latter ones have been reoperated. Fig. 1 summarises the courses of transvalvular and PA pressure gradients. It shows that the PA gradients remain constant throughout the whole follow up.

3.4.2. Contegra® valve incompetence
During the whole follow-up, there was no valvular incompetence at all detectable in 20 patients (28%). A trivial to mild incompetence was seen in 32 patients (45%). Nineteen patients (27%) presented with a moderate pulmonary incompetence which decreased spontaneously to mild or trivial values in 14 cases during the follow-up (Fig. 2 ). Up to now, we observed no severe Contegra® valve incompetence. Irrespective of the postoperative grade, the incompetence had no tendency at all to increase during the whole follow-up, as shown in Fig. 3 . Fig. 4 shows the course of RV/LV diameter ratio, standardised to the ratio found at the first month examination. The ratio did not change throughout the whole follow-up and resembled the standardised RV/LV ratio of the homograft group for a comparable observation time (30 months). The RV/LV ratio was significantly correlated to the degree of pulmonary incompetence (Fig. 5 ), but independent from the PA bifurcation pressure gradient (Fig. 6 ). In patients who presented with both pulmonary valve incompetence and peripheral pulmonary artery stenosis, the degree of peripheral stenosis did neither increase the degree of valve incompetence nor the RV/LV ratio (Fig. 6).



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Fig. 2. Development of mean incompetence grades of all echo examinations at the relative follow-up intervals. There is no tendency to increase (PVI, pulmonary valve insufficiency).

 


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Fig. 3. Contegra® conduit valve incompetence development related to the first preoperative month. Incompetence grade development was plotted here grouped by the incompetence grade seen at the first month examination in order to see whether there is a rising trend over time. This is not the case. In contrast, an initially ‘mild to moderate’ or ‘moderate’ incompetence seems to decrease (PVI, pulmonary valve insufficiency).

 


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Fig. 4. RV/LV ratio development with Contegra® compared to homografts. To compare ventricular size development of the two conduit kinds, we standardised the RV/LV ratios: all measured ratios were related to the individual patient's RV/LV ratio that was found at the 1 month examination. The figure shows no superiority of homografts in this regard.

 


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Fig. 5. Relation between conduit incompetence and RV/LV ratio. Valve incompetence increases the ventricle: this is true also for Contegra® conduit patients. The low R2 value may be due to the low number of examinations showing insufficiencies that are higher than mild.

 


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Fig. 6. There is no additive effect of incompetence and distal pressure gradient on ventricular size. This figure serves to show several facts: first, we see that more insufficiency means larger right ventricles. Second, we see this trend confirmed for three different ranges of gradients beyond the valve. Third, we see that the relative RV size increase related to valve insufficiency is not bolstered by a distal PA gradient. Otherwise the three bar groups as a whole would move towards higher RV/LV ratios with increasing PA gradient.

 
3.4.3. Conduit dilatation
In four of the 71 patients, the maximal increase of the measured conduit diameter (60–80% related to the implant diameter) was observed. The echocardiographic determination of the conduit diameter is subject to uncertainties caused by angulation between probe and blood flow direction, squeezing of the conduit by the surrounding structures and by the actual filling pressure of the conduit. In our large series of postoperative echocardiographies, we found variations of diameter ratios from 0.4 to 1.8 related to the indicated diameter of the native conduit, but the expected correspondent flow velocity change was described very rarely. We also saw a great variability of the measured diameters in the same patients, without constant trends. In absence of any clinically relevant effects, we have no reason to be concerned about conduit dilatation up to now.

3.4.4. Survival, freedom from explantation and reoperation
The survival curves of patients with Contegra® conduits, homografts, and porcine xenografts are shown in Fig. 7 . Although the differences were not yet significant, patients with a Contegra® conduit had the best survival rate. In Fig. 8 , freedom from conduit explantation of the three cohorts is shown. Up to now, no Contegra® conduit had to be explanted. That differed significantly from homografts (P=0.015) as well as from porcine xenografts (P<0.01). For the same observation period (2.25 years), freedom from explantation was 86% for the homograft group and 25% for the porcine xenograft group. Freedom from both explantation and reoperation was similar for Contegra® and homografts; both were significantly better (P<0.01) than porcine xenografts (Fig. 9 ).



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Fig. 7. Survival after RVOT reconstruction with different kinds of conduits. Better survival of Contegra® recipients might be partially explained by less extensive reoperations: reoperation for bifurcation stenosis after Contegra® conduits was always limited to bifurcation plasty, while homo- and porcine xenografts had always to be entirely explanted when a revision was done.

 


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Fig. 8. Freedom from explantation of different kinds of conduits. Concerning freedom from explantation in our patient population, at 27 months Contegra® conduits are significantly superior to homo- and porcine xenografts.

 


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Fig. 9. Freedom from explantation or reoperation of different kinds of conduits. Contegra® conduits behave comparable to homografts, both are significantly superior to porcine Tissuemed® xenografts. However, homografts were always explanted during reoperations, while Contegra® reoperations were necessary only for stenoses or (in one case) dilatation of the patients' pulmonary vessels beyond the conduit.

 

    4. Discussion
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 
In this study, we report our experience with the Contegra® conduit implanted in pediatric patients requiring RVOT reconstruction. RVOT reconstruction by means of a conduit is necessary in a wide range of complex cardiovascular malformations particularly in infancy and early childhood. It is generally accepted that valved conduits should be used as the first choice [9]. Homografts are considered as gold standard [10,11]. However, homografts often show early degeneration and calcification, particularly in very young patients [12]. Primarily due to shortage of small homografts and after disappointing experiences with porcine aortic xenografts [7], we started to implant Contegra® conduits in May 1999 as part of an FDA-controlled extended phase I study approved by the local ethics committee. The Contegra® conduit consists of an exceptionally pliable tissue and therefore offers unique qualities for surgical handling. The abundant tissue at both sides of the valve allows enhanced implantation techniques. Suturing is rather easy and the material is resistant to suture tear. Further foreign material for the proximal anastomosis is not necessary. It has to be noted that the Contegra® conduit contains a high profile valve. The bovine jugular venous valve leaflets are longer in direction of the conduit tube than homo- or xenograft valves. As a result, particularly in infants, the valve often requires almost the whole conduit length from the proximal to the distal anastomosis and has therefore to be positioned as distal as possible. The Contegra® conduit allows the surgeon easily to implant the graft leftwards to avoid the risk of damaging the conduit during a later sternotomy. By serial sonography, the Contegra® conduit did not show any signs of degeneration or calcification in the whole follow-up period (maximum 27 months). Up to now, there were no device-related adverse events. No Contegra® conduit had to be explanted due to stenosis or valve incompetence. In contrast to that, 14% of the homograft conduits and 75% of the porcine xenograft conduits had to be explanted within the same observation period. The measured pressure gradients at the Contegra® conduit valvular level were zero or insignificant in 90% of the patients. The remaining cases presented maximal pressure gradients of 25–32 mmHg. More frequent and clinically important were pressure gradients at the level of the distal anastomosis to pulmonary artery bifurcation. They were due to the abrupt reduction of vascular size at the end of the conduit (diameter>=12 mm) and the beginning of the native pulmonary artery branches (often 4 mm), particularly in cases with TAC A2. In some patients, it was rather difficult to distinguish between transvalvular and pulmonary artery gradients, since the distance between the conduit valve and the pulmonary artery bifurcation was quite small.

A conduit diameter increase (of 60–80%) was seen transiently in two and actually in further two patients. Both findings were inconsistent and not related to increased pulmonary vascular resistance. We have no evidence of any relevant conduit dilatation. However, severe conduit dilatation and subsequent valve incompetence is reported to occur also in Contegra® conduits by Segesser (Lucerne, Switzerland) and Lindberg (Oslo, Norway) (both personal communications).

Up to now, five patients needed secondary plastic augmentation of the pulmonary bifurcation including the origins of both pulmonary arteries. At present, the distal anastomosis is performed including a more extended augmentation plasty that reaches into the pulmonary artery branches. Although not statistically significant, survival rate 27 months after Contegra® conduit implantation was better compared to homograft implantation. This might be partially explained by the easier implantation technique of the bovine venous conduit. The majority of Contegra® conduits present a trivial to mild incompetence right from the first examination, but only very few cases presented a moderate incompetence. Up to now, no severe incompetence was seen. However, its degree did not increase over time as frequently observed in homograft conduits [13,14]. This was supported by the constant RV/LV ratio during the whole follow-up. Comparing the three conduit groups with respect to their mid-term rates of explantation or reoperation, the Contegra® group performed equal to the homograft group; both groups were significantly better than porcine xenografts. Neither the deaths (five early and one late) nor the reported seven reoperations in the Contegra® group were conduit related. Five of the six deaths were primarily due to operated high-risk patients. Hypoplastic pulmonary artery branches are easier to augment using a Contegra® conduit than using a homograft.


    5. Conclusion
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 
Due to its unique qualities, the new Contegra® bovine valved venous xenograft offers many advantages compared to homografts and particularly compared to porcine xenografts. It is suitable for newborns and adults. Implantation is safer and far easier for the surgeon. The short Contegra® follow-up time is a limitation of the study. During the presented 27-month follow-up, conduit function was at least as good as it was for homografts and was by far superior to porcine xenografts. The lack of any degeneration signs after 27 months lets us hope that the Contegra® conduit might become a promising alternative to the homograft, the still well-accepted golden standard. We are continuing the intense follow-up to gain long-term results.


    Footnotes
 
Presented at the joint 15th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 9th Annual Meeting of the European Society of Thoracic Surgeons, Lisbon, Portugal, September 16–19, 2001.


    Appendix A. Conference discussion
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 
Dr H. Al Qethamy (Riyadh, Saudi Arabia): I am wondering, how can you size this Contegra? Do you have a table? How do you know that this baby or this child needs such a size is the first question?

Dr Breymann: We do it in the same way as we would do it in the case of homograft implantation, of course. And as you have seen most of our patients are primary repairs in the first six months of life, so the most suitable one is the 12 mm Contegra.

Dr Al Qethamy: Do you size it by Hager or just whoever is less than six months you just decide?

Dr Breymann: What do you mean, sizing of the Contegra graft itself or sizing what is appropriate?

Dr Al Qethamy: The Contegra graft, it is many sizes, isn't it? It is not only one size?

Dr Breymann: There are sizes available from 12 mm to 22 mm.

Dr Al Qethamy: Exactly. How do you know that this baby required 12 or 20 or 16? Do you have a theory?

Dr Breymann: I can answer that in another way. I would say I decided it exactly the same way I would decide for homograft sizes.

Dr F. Lacour-Gayet (Hamburg, Germany): If I can add something: we have tables. But the question that is asked to you, is what maximum would you consider for oversizing. In another term, is oversizing dangerous or not?

Dr Breymann: Too much oversizing is dangerous, of course, but the smallest one is 12 mm, and in case of truncus arteriosus for instance, we often see pulmonary artery branches of 4 to 5 mm. So what to do? And this leads to some problems in peripheral stenosis. I have showed you that we have had five peripheral pulmonary artery problems, and they have to do with this, of course.

Dr J. Amato (Chicago IL, USA): I hate to be repetitive because I discussed this at a previous conference this morning. We have very little experience in the United States compared to you all in Europe, but having practiced for 30 years and having gone through the INF deal with the Hancock to the pulmonary or aortic homografts, we have only implanted in the United States I think less than 20 of them, but we find it to be a very superior graft for many reasons: It is easy to handle; the sizing can be sized by any index that you want to size it by; we have had no problems with it, and I know other people have had problems with it. So far in the Bove series, the Brown series, my series, there are about 15 of us in the United States that are implanting them, I find it to be a very superior structure. So I am looking forward to it as the choice of replacement.

We cannot get the smaller pulmonary homografts in the United States as much as we want to, and these, as you say, are off the shelf, they can be easily washed and put in place, and we have had no problems with it so far.

Dr Breymann: The main reason for starting this study in our institution has been exactly that reason, the shortage for homografts, particularly for the small ones.

Dr Amato: That was an excellent paper, excellent results.

Dr M. Wojtalik (Poznan, Poland): I have implanted over 20 such grafts. Our material is a bit different. The biggest group is the Ross group. And this graft has two advantages over the homograft: the first is the small size availability, and the second is that it is ready for use at the theater. So any time you can ask for implantation. There are also more advantages, that the valve can be positioned in any place due to excess of tissue on both ends.

You did reoperate on some patients, and I myself too, and there is jelly-like tissue on the distal part of the suture line. Did you encounter such jelly-like tissue?

Dr Breymann: Many of your comments I couldn't understand.

Dr Lacour-Gayet: Would you raise the question to the speaker after your comment, please?

Dr Wojtalik: The conclusion was that there are no complications, and still myself and my colleagues encounter peripheral stenosis due to jelly-like tissue in the suture line. The question is whether you encountered such a finding during reoperation?

Dr Breymann: We have seen these jelly deposits peripheral of the suture line. We had five redos, one reduction plasty and four times an augmentation plasty, and we didn't have any need to resolve the peripheral suture line of the conduit, and all patients we have reoperated are doing very well up to now.

Dr A. Corno (Lausanne, Switzerland): The conduit comes commercially available in two types, one is stented and one unstented. Which one do you use and why?

Dr Breymann: Only the unstented ones.

Dr Corno: We do the same, as you know. I didn't see any Ross patients in your series.

Dr Breymann: No.

Dr Corno: Why?

Dr Breymann: From my standpoint it is a simple answer, because we have some homografts and we preserve these homografts for the Ross procedures because we think they fit in this situation absolutely perfect. That is our feeling.

Dr Corno: Do you consider a contraindication this conduit?

Dr Breymann: No.

Dr H. Lindberg (Oslo, Norway): We have a very small limited experience but we have seen dilatation in the very tiny babies where you have a growth causing peripheral stenosis, and we could demonstrate that by MRI and echo. Haven't you seen any dilatation?

Dr Breymann: Honestly, we haven't seen anything like that, and I have discussion slides here. We have looked for a relationship between conduit insufficiency and high pressure in the conduit. Because not all of these babies have tricuspid insufficiency, we took as a parameter the whole RVOT gradient and we looked whether there is any correlation between the RVOT gradient and the insufficiency, and there is a correlation, but a very slight one. But dilatation we have honestly never seen.

Dr W. Daenen (Leuven, Belgium): I have a similar question. We have done 32 cases now. We had one patient after truncus arteriosus who had right ventricle pressure at systemic level and the diameter of the conduit increased, it doubled in size, and got incompetent.

Dr Breymann: In our experience with that, we had two patients from the very beginning, and the follow-up of these two patients is more than two years. One of them has primary pulmonary vascular resistance and pressure in the right ventricle of over 100 mmHg, and there is no insufficiency. This valve functions up to now perfectly. So sometimes it might dilate, sometimes not, but it is the same with the homografts as well.

Dr Z. Al-Halees (Riyadh, Saudi Arabia): After all is said, and it is well and good, I think, but we still have to understand that it is a very short follow-up, and we have the gold standard of the homograft, and I think failures generally start five years later. So I think unless we have at least a five-year follow-up, we still should be cautious about the widespread use of the single conduit.

Dr Breymann: I agree so far that we need time for further follow-up, of course.


    References
 Top
 Abstract
 1. Introduction
 2. Patients and methods
 3. Results
 4. Discussion
 5. Conclusion
 Appendix A. Conference...
 References
 

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