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Ann Thorac Surg 1996;62:155-160
© 1996 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Long-Term Follow-up of Autologous Pericardial Valved Conduits

Division of Pediatric Cardiac Surgery and Cardiology, Hospital de Niños "Ricardo Gutierrez" and Clínica Bazterrica, Buenos Aires, Argentina

Accepted for publication March 5, 1996.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Background. The aim of this study was to evaluate the long-term results of the use of an autologous pericardial valved conduit in the outflow tract of the venous ventricle in congenital heart malformations.

Methods. Fifty-one patients were followed up for a period of 12 to 120 months; 30 for more than 36 months and 13 for more than 72 months. All were evaluated clinically and by two-dimensional and Doppler echocardiography. Eight patients were recatheterized. Postoperative evaluation included serial measurement of pressure gradients and the conduit's diameter at the proximal, valvular, and distal levels. Reoperation because of stenosis was indicated when the gradient across the right ventricular outflow was greater than 50 mm Hg. The reoperation rate in relation with postoperative time, diameter of the autologous pericardial valved conduit at the time of implantation, and malformation was statistically analyzed.

Results. In 27 patients the conduit increased its diameter 1 to 7 mm. In 20 patients the diameter remained unchanged, whereas a reduction was noted in 4. Conduit survival free of reoperation for the whole group was 89.9% at 5 years. Conduit survival free of reoperation was 100% at 5 and 7 years for conduits larger than 16 mm at the time of implantation. It was 95% (standard deviation = 4.8%) at 5 years and 72.3% at 7 years for those 16 mm or less. For patients operated after January 1, 1986 (technical modification), conduit survival free of reoperation was 95.4% at 7 years postoperatively.

Conclusions. These results compare favorably with those of other available conduits.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Since the first report in 1966 of a homograft conduit used by Ross and Sommerville [1] to reconstruct the right ventricular outflow tract, different types of valved and nonvalved conduits have been widely used to connect the venous ventricle with the pulmonary artery (PA). Several valved conduits, such as irradiated, fresh, antibiotic-preserved, or cryopreserved homografts and heterografts, have been used. None proved to be ideal, because they all tend to deteriorate with time, which reduces the lumen, and they do not have the capacity to increase their diameter with time, as use in pediatric patients would require.

In spite of the immediate good surgical result, most of these grafts have to be replaced in a relatively short period of time (45% during the first 5 years) [2]. Other authors have shown a significantly lower reoperation rate for pulmonary than for aortic cryopreserved homografts [3].

In 1965 the use of a nonvalved pericardial conduit was reported [4, 5] in a patient who even today after 30 years is in good condition, not needing a reoperation. The presence of a valve in a conduit is necessary, especially during the immediate postoperative period. Furthermore, it is generally required if the patient has some degree of pulmonary hypertension or other restriction to pulmonary run off, or impairment of the function of the left side of the heart.

Based on our and others' experience with the use of unpreserved pericardium to enlarge the right ventricular outflow tract in the correction of tetralogy of Fallot and on the fact that it does not tend to shrink when used in that position [6–9], since June 1983 we considered the possibility of constructing a valved conduit with unpreserved autologous pericardium when no previous adhesions were present. The aim was to insert a conduit that would not need replacement, or at least, would have a lower incidence of reoperations than the currently available conduits. The purpose of this report is to review the intermediate and long-term follow-up (minimum follow up period, 12 months) of 51 consecutive patients in whom an unpreserved autologous pericardial valved conduit (APVC) was implanted.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Surgical Technique
After we remove the pericardium from the left to the right phrenic nerve and from the aorta to the diaphragm, we manufacture the conduit as previously reported [10, 11] (Fig 1). The diameter is selected according to the patient's body surface area [12], but trying to construct it as large (in diameter) as the patient permits. The length of the conduit is determined by measuring the distance between the PA distally and the site of the ventriculotomy proximally. Thus the conduit is tailored custom made for the patient.

View larger version (49K): [in this window] [in a new window]   Fig 1. . Construction of the pericardial conduit: (1) Pericardial trapezoid (see Table 1): (a-a' = the wider base, 10% larger than A-A' of the rectangle; b = midpoint of the trapezoid [commissure of the bicuspid valve], H = height of the valve). (2) Pericardial rectangle with wider distal end. The trapezoid has already been superimposed. (A-A' is the width of the rectangle, selected according to the desired conduit diameter, b = the midpoint between A and A'). (3) Three double-armed sutures are placed securing the trapezoid to the rectangle at A-a, A'-a', and at b. (4) The trapezoid is trimmed, resecting three triangles from the lesser base, giving form to the future cusps. (5) A running suture is performed from A and A' following the edge of the rectangle in the first 3 mm and from b to secure the future cusps to the rectangle. The first 3 mm of the suture started at b is a double-line suture. (6) The pericardium, with the valves inside, is wrapped around a Hegar dilator of the corresponding diameter. (7) A double running suture is performed to close the conduit. The suture is started at the distal end, and is not tied at the proximal end to adjust its length to the patient's needs. (8) The completed conduit.

In only 1 case was it necessary to supplement the proximal end by implanting a gusset of polytetrafluoroethylene (Gore-Tex; W. L Gore & Assoc, Flagstaff, AZ) when the conduit was not long enough to permit a good anastomosis. The longest conduits are usually those used to connect the venous ventricle with the PA in cases of L-transposition of the great arteries.

Before the chest is closed, the pericardium is replaced by a Gore-Tex 0.1-mm pericardial membrane to avoid any damage to the phrenic nerves.

At the beginning of our experience, 4 patients presented with some degree of distal line stenosis, so since 1986 we decided to construct the distal end of the APVC 4 mm wider to make the distal anastomosis larger. In addition, at that time we started to perform this suture line in four quadrants, adjusting the suture over the matching Hegar dilator.

Conduits were placed to the left of the aorta in 37 patients, whereas in 14 patients with L-transposition of the great arteries had to be placed to the right of the aorta.

Patient Population
The first patient was operated upon on June 1983. Since then 51 consecutive survivors in whom an APVC was implanted were evaluated as to their conduit's result. Follow-up time ranged between 12 and 120 months with a median of 50 months. Thirty patients were followed up for more than 36 months and 13 for more than 72 months.

The age of the patients ranged between 3 and 288 months (median, 60 months). Ten of the patients were younger than 12 months old. Table 2 describes the preoperative diagnosis of the 51 patients. The distribution by sex was similar: 26 male and 25 female patients (Table 2).

Eight patients were subjected to hemodynamic evaluation. Chest roentgenography was performed in all patients every 6 months to search for calcification of the conduit. Two-dimensional Doppler echocardiography was shown to be highly accurate at evaluating the conduits, as had been previously reported by Chan and associates [13] (Fig 2).

View larger version (8K): [in this window] [in a new window]   Fig 2. . Postoperative two-dimensional echocardiographic evaluation of autologous pericardial valved conduit inserted in a patient with double-outlet left ventricle (DOLV) and pulmonary stenosis (PS). The conduit and the pulmonary valve are seen. Distal and proximal end sutures are measured. (AO = aorta; LPA = left pulmonary artery; ORV = right ventricular outlet; PC = pericardial conduit; PV = conduit's pulmonary valve; RPA = right pulmonary artery.)

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
No or trivial conduit valve regurgitation was measured during the first postoperative months. A moderate diastolic murmur due to conduit valve incompetence was observed after 12 to 18 months postoperatively without any impact on patients' hemodynamic status.

The median diameter of the implanted conduits was 16 mm, compared with 17.2 mm at the time of the last evaluation (Wilcoxon test p = 0.00012). Measurements revealed that the conduit's diameter increased by 1 to 7 mm in 27 patients, remained unchanged in 20, and had a reduction of 1 to 2 mm in only 4 patients.

Gradients measured by two-dimensional Doppler echocardiography ranged from 0 to 82 mm Hg (median, 21 mm Hg). Twenty patients had gradients of more than 20 mm Hg, whereas in 31 patients it was less than 20 mm Hg.

Of the 51 patients, 9 were subjected to ten reoperations. Six of the ten reoperations were conduit related, whereas four were not (2 cases of residual ventricular septal defect and 1 each of truncal valve regurgitation and left ventricular outflow tract obstruction).

Conduit reoperation was indicated according to the pressure gradient across the venous ventricular outflow tract. The six patients reoperated on because of obstruction at the conduit level had gradients that ranged between 30 and 82 mm Hg (median, 48 mm Hg). The relationship between the original malformation and conduit-related and unrelated reoperation is shown in Figure 3.

View larger version (17K): [in this window] [in a new window]   Fig 3. . Incidence of reoperations according to malformation corrected. The highest incidence of conduit-related reoperation is seen among the truncus arteriosus group. Ten patients in this group were subjected to four reoperations. Of these, 3 were conduit related. (This was the group who received the conduits of the smallest diameter.) Of the 16 patients of the transposition of the great arteries (TGA) group, 4 were reoperated on. Two of these reoperations were conduit related. Of the 25 patients of the other three groups together, only 2 had to be reoperated on. One of these was conduit related. (Pulm. Atr. = pulmonary atresia.)

In 3 patients a uniform diameter was observed at reoperation; however, the patients had outgrown the conduit's diameter. Two of the 6 patients who underwent reoperation presented with some degree of calcification of the conduit's wall.

In none of the patients was the obstruction found to be at the valvular level. The valve was recognized and found to be pliable only in those patients reoperated on before the 6th postoperative month whose reoperations were unrelated to the conduit. In those patients reoperated on after a longer follow-up period, the valve could not be identified, and only the suture line was visible in the wall at the previous level of implantation.

The accumulated probability of conduit survival without conduit-related reoperation for the whole group is 95.6% (standard deviation, 4%) at 3 years and 89.6% at 5 years, as shown in Figure 4.

View larger version (12K): [in this window] [in a new window]   Fig 4. . Reoperation-free conduit survival. The probability of reoperation-free conduit survival in the 51 patients was 95.6% (standard deviation = 4%) 3 years postoperatively and 89.6% at 5 years.

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment References

Prevention of conduit valve incompetence was our first priority in this project because, if present during the most important period of pulmonary valve competence (immediately after operation), it could have an impact on hemodynamic results. It would have less or no impact if it appeared in the intermediate or long term, as usually pulmonary vascular resistances tend to decrease with time after total correction.

Fortunately, the intermediate and long-term follow-up seem to demonstrate that conduit valve incompetence does not represent an important problem. In the postoperative two-dimensional Doppler echocardiographic evaluations, no or trivial valve incompetence was found during the first months. On the other hand, after 18 months, moderate to severe valve regurgitation was shown to be present without having any impact on the patients' hemodynamic status. None of the patients in this series has had to be subjected to valve implantation so far because of right ventricular failure induced by pulmonary valve regurgitation.

The second and most important challenge for the APVC was to compare the rate of progressive obstruction and thus the need for reoperation with that of the other available conduits. Two-dimensional Doppler echocardiographic evaluation of the conduit's diameter at the proximal, valvular, and distal level, as well as pressure measurements, were performed. Of the 51 implanted conduits, with a median follow-up time of 50 months, 27 (52%) increased in diameter. We do not consider this real growth, but real enlargement of the conduit at all the different measured levels was present. This represents an invaluable advantage when compared with all the available conduits. Only four of the conduits (7.8%) decreased in diameter. The median diameter for the 51 conduits was 21 mm, which compares favorably with the results of the other conduits. Cryopreserved homografts have shown to have up to 20% reoperation rate at 3-year follow-up and 45% at 5 years because of gradients due to stenosis [2, 3]. Early calcifications and obstruction were reported with the use of cryopreserved homografts, and even a tissue rejection was presented as a hypothesis by a group that advocated the use of some immunosuppressive drugs to prevent these effects. This is not a problem with autologous pericardial valved conduits.

The changes in conduit construction and implantation techniques in January 1986 led to a decreased incidence of distal-end suture stenosis and thus a decreased reoperation rate. The impact of these changes is still more noticeable in the fact that 5 of the 6 reoperations due to conduit stenosis were performed on patients operated on before that date. As all of the conduits that needed reoperation were less than 16 mm in diameter at the time of implantation, our present policy is to implant the widest conduit that the patient and the available pericardium permits.

The actuarial conduit survival free of reoperation (± standard deviation) in the patients operated on after the technical modification was 95.5% ± 8.7% at up to 7 years of follow-up. Figure 5 shows the actuarial survival curve for these patients.

View larger version (13K): [in this window] [in a new window]   Fig 5. . Freedom from conduit reoperation actuarial curve after technical modification. The 43 patients operated on after the technical modification are included. The probability of conduit survival at 7 years of follow-up was 95.5 (standard deviation = 8.7%). (+ Results at 36 and 60 months obtained with cryopreserved homografts by Cleveland and associates [2]; to be able to compare results, the same statistical methodology was used.)

The technique we used to enlarge the conduit at reoperation, when indicated, was to open it longitudinally up to the left PA and then enlarge it with a Gore-Tex patch. No valve was inserted.

We conclude that there is no ideal conduit available yet. An ideal conduit should not only enlarge in diameter with the patient's age, but it should also have a long-lasting valvular function.

The APVC showed good valve competence during the first postoperative months, the time in which it is most important for the patient's survival. Regarding the diameter's "growth," the results with the APVC were much better than with the other conduits. Although some incidence of reoperation because of conduit stenosis was present, it was undoubtedly less than with the other conduits.

The minimal cost of the APVC is an advantage that has to be kept in mind, especially in developing countries, and nowadays everywhere. Neither expensive stocking of conduits of different diameters nor sterilization is needed.

The most important disadvantages the use of APVC presents are that it cannot be used in the presence of extensive pericardial adhesions and that it has a shorter period of valve competence. The use of an APVC is a valid alternative when a conduit is needed to connect the venous ventricle with the PA, and may be a good option for the Ross operation.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Address reprint requests to Dr Schlichter, Unidad 17, Cirugia Cardiovascular, Hospital de Niños "R. Gutierrez," Gallo 1330, Buenos Aires, 1425, Argentina.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 

1. Ross DN, Sommerville J. Correction of pulmonary atresia with a homograft aortic valve. Lancet 1966;2:1446–7.[Medline]
2. Cleveland DC, Williams W, Razzouk J, et al. Failure of cryopreserved homograft valved conduits in the pulmonary circulation. Circulation 1992;86(Suppl 2):150–3.
3. Bando K, Danielson GK, Schaff HV, Mair DD, Julsrud PR, Puga FJ. Outcome of pulmonary and aortic homografts for right ventricular outflow tract reconstruction. J Thorac Cardiovasc Surg 1995;109:509–18.[Abstract/Free Full Text]
4. Rastelli GC, Ongley PA, Davis GD, Kirklin JW. Surgical repair for pulmonary valve atresia with coronary pulmonary fistula: report of case. Mayo Clinic Proc 1965;40:521–7.[Medline]
5. Cerfolio RJ, Danielson GK, Warnes CA, et al. Results of an autologous tissue reconstruction for replacement of obstructed extracardiac conduits. J Thorac Cardiovasc Surg 1995;110:1359–68.[Abstract/Free Full Text]
6. Hjelms MD, Pohlner P, Barratt-Boyes BG, Gavin JB. Study of autologous pericardial patch grafts in the right ventricular outflow tracts in growing and adult dogs. J Thorac Cardiovasc Surg 1981;81:120–3.[Abstract]
7. Mohri H, Barnes RW, Rittenhouse EA, Reichenbach DD, Dillard DH, Merendino KA. Fate of autologous pericardium and Dacron fabric used as substitutes for total atrial septum in growing animals. J Thorac Cardiovasc Surg 1970;59:501–11.[Medline]
8. Egerton WS, Windsor MF. Assessment of autogenous and prosthetic materials in the right ventricular outflow tract. Aust NZ J Surg 1965;35:63–7.[Medline]
9. Gabbay S, Bortolotti U, Factor S, Shore DF, Frater RWM. Calcification of implanted xenograft pericardium: influence of site and function. J Thorac Cardiovasc Surg 1984;87:782–7.[Abstract]
10. Schlichter AJ, Kreutzer GOA. Autologous pericardial valved conduit (APVC). Rev Lat Card Inf 1985;1:43–8.
11. Schlichter AJ, Kreutzer GOA, Suarez JC, et al. Seguimiento de los tubos valvulados de pericardio autólogo. Rev Lat Card Inf 1987;3:193–200.
12. Pacifico AD, Kirklin JW, Blackstone EH. Surgical management of pulmonary stenosis in tetralogy of Fallot. J Thorac Cardiovasc Surg 1977;74:382–95.[Abstract]
13. Chan KC, Fyfe DA, McKay CA, Sade RM, Crawford FA. Right ventricular outflow reconstruction with cryopreserved homografts in pediatric patients: intermediate term follow-up with serial echocardiographic assessment. J Am Coll Cardiol 1994;24:483–9.[Abstract]
14. Friedman LM, Furberg CD, De Mets DL. Fundamentals of clinical trials. 2nd ed. Littleton, MA: PSG Publishing Co, 1985.
15. Coldman AJ, Elwood JM. Examining survival data. CMA J 1979;121:1065–70.[Abstract]

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Andres J. Schlichter Christian Kreutzer Jorge L. Simon Guillermo O. A. Kreutzer Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schlichter, A. J. Articles by Kreutzer, G. O. A. Search for Related Content PubMed PubMed Citation Articles by Schlichter, A. J. Articles by Kreutzer, G. O. A.