MR and CT imaging of pulmonary valved conduits in children and adolescents: normal appearance and complications.

BACKGROUND: The Contegra® is a conduit made from the bovine jugular vein and then interposed between the right ventricle and the pulmonary artery. It is used for cardiac malformations in the reconstruction of right ventricular outflow tract. OBJECTIVE: To describe both normal and pathological appearances of the Contegra® in radiological imaging, to describe imaging of complications and to define the role of CT and MRI in postoperative follow-up. MATERIALS AND METHODS: Forty-three examinations of 24 patients (17 boys and 7 girls; mean age: 10.8 years old) with Contegra® conduits were reviewed. Anatomical description and measurements of the conduits were performed. Pathological items examined included stenosis, dilatation, plicature or twist, thrombus or vegetations, calcifications and valvular regurgitation. Findings were correlated to the echographic gradient through the conduit when available. RESULTS: CT and MR work-up showed Contegra® stenosis (n = 12), dilatation (n = 9) and plicature or twist (n = 7). CT displayed thrombus or vegetations in the Contegra® in three clinically infected patients. Calcifications of the conduit were present at CT in 12 patients and valvular regurgitation in three patients. The comparison between CT and/or MR results showed a good correlation between the echographic gradient and the presence of stenosis in the Contegra®. CONCLUSION: CT and MR bring additional information about permeability and postoperative anatomy especially when echocardiography is inconclusive. Both techniques depict the normal appearance of the conduit, and allow comparison and precise evaluation of changes in the postoperative follow-up.

Evolution of the Z-score in size-reduced bicuspid homografts.

BACKGROUND AND AIM OF THE STUDY: Human homografts are frequently used to establish an anatomic continuity between the right ventricular outflow tract (RVOT) and the pulmonary artery. Their limited availability, especially in small sizes, has encouraged the use of alternative strategies, such as size-reduced bicuspid homografts. The study aim was to analyze the follow up of patients who had received a standard tricuspid or size-reduced bicuspid homograft in the RVOT position, and to investigate modifications of the patients' Z-scores over the years. METHODS: A consecutive series of 107 patients aged < or = 16 years, who underwent RVOT repair between 1989 and 2010 to treat tetralogy of Fallot (ToF), was retrospectively reviewed. Of these patients, 17 received a size-reduced bicuspid pulmonary homograft, while 90 received a standard tricuspid homograft. The mean follow up periods were 10.5 years (range: 0.02-21.4 years) for the whole study population, and 11.8 years and 3.4 years, respectively, for the tricuspid and size-reduced bicuspid homograft groups. RESULTS: Freedom from mortality at 10 years was 95 +/- 3%. During the observation period, 27 patients (31%) in the tricuspid homograft group and two (125) in the size-reduced bicuspid group presented with graft failure. According to the multivariable analysis, the only independent predictor of graft failure was patient age (hazards ratio 0.86). The 17 patients who had received a size-reduced bicuspid homograft were then age-matched to an equal-sized population of tricuspid homograft patients. A comparative analysis of the time-weighted average of the Z-scores for these tricuspid and size-reduced bicuspid homograft subgroups during the follow up period failed to identify any statistical difference (p = 0.5). CONCLUSION: In terms of Z-score evolution, size-reduced bicuspid homografts offer results which are comparable to those achieved with tricuspid homografts.

Functional analysis of bioprosthetic heart valves.

Glutaraldehyde-treated bovine pericardium is used successfully as bioprosthetic material in the manufacturing of heart valves leaflets. The mechanical properties of bovine pericardial aortic valve leaflets seem to influence its mechanical behaviour and the failure mechanisms. In this study the effect of orthotropy on tricuspid bioprosthetic aortic valve was analysed, using a three-dimensional finite element model, during the entire cardiac cycle. Multiaxial tensile tests were also performed to determine the anisotropy of pericardium. Seven different models of the same valve were analysed using different values of mechanical characteristics from one leaflet to another, considering pericardium as an orthotropic material. The results showed that even a small difference between values along the two axes of orthotropy can negatively influence leaflets performance as regard both displacement and stress distribution. Leaflets of bovine pericardium bioprostheses could be manufactured to be similar to natural human heart valves reproducing their well-known anisotropy. In this way it could be possible to improve the manufacturing process, durability and function of pericardial bioprosthetic valves.

Structural changes in a porcine xenograft after implantation for 105 months.

Morphologic studies including light microscopy and transmission and scanning electron microscopy were performed on a formaldehyde-fixed porcine xenograft prosthesis that functioned well for 8 years and had been implanted for 105 months in the tricuspid valve position. It is the oldest implanted valve studied in this manner. Although all leaflets had some gross deterioration, only one had adherent thrombus. The degenerative changes in the connective tissue from all leaflets were similar to those recently reported in glutaraldehyde-fixed porcine valves implanted for shorter periods. The surfaces of the two nonthrombosed leaflets and small portions of the surface of the thrombosed leaflet were endothelized, and the endothelium appeared to have little or no effect on the degenerative changes in the subjacent connective tissue. Further, the endothelium did not extend over the examined portion of the synthetic anulus of the prosthesis, suggesting that its origin was possibly from cells circulating in the blood.

Usefulness of bicuspid homograft reconstruction of the right ventricular outflow tract in infants with complex congenital heart disease.

Homograft supply is limited especially for those sizes required for neonatal and infant cardiac operations. Surgically downsized homografts have been successfully used for right ventricular outflow tract reconstruction in 5 children (mean weight 6.2 kg) with evidence of good hemodynamic performance of the conduits at a mean follow-up time of 3.7 years.

Evaluation of hemolysis following replacement of atrioventricular valves with procine xenograft (Hancock) valves.

Twenty-two patients who had undergone valve replacement with the porcine xenograft were studied 6 to 62 months postoperatively (mean 30.5 months) for evidence of intravascular hemolysis. Hemolysis was not detected in any patient and postoperative red cell indices and iron studies were normal for the majority of patients. Five patients had significantly elevated serum lactic dehydrogenase (LDH) values preoperatively which returned to normal following operation. Our evidence suggests that the glutaraldehyde-fixed porcine xenograft valve does not cause detectable hemolysis.

Combined tricuspid and pulmonic stenosis. Clinical, echocardiographic, hemodynamic, surgical, and pathological features.

A 30-year-old man with a history of a murmur since childhood had progressive ascites for 2 years. The patient was found to have severe stenoses of the pulmonic and tricuspid valves with a well-developed right ventricle. Impressive clinical improvement occurred after pulmonic valvotomy, infundibulectomy, and replacement of the stenotic tricuspid valve with a porcine xenograft. The clinical, echocardiographic, hemodynamic, surgical, and pathological features are presented.

Tricuspid regurgitation. A comparison of nonoperative management, tricuspid annuloplasty, and tricuspid valve replacement.

The best means of managing tricuspid regurgitation associated with mitral or mitral and aortic valve disease is still to be determined. During the period 1972 to 1974, we treated 76 patients who had tricuspid regurgitation along with associated valvular dysfunction. Patients with mold regurgitation were treated conservatively, those with moderate regurgation underwent annuloplasty, and those with severe regurgitation had tricuspid valve replacement. We found the results to be less satisfactory in the group treated by annuloplasty than in the other two groups. We still manage conservatively those patients with mild regurgitation, but we believe it appropriate to replace the valve in an increasing number of subjects who have tricuspid regurgitation of moderate severity.

Unstented semilunar homograft replacement of tricuspid valve in Ebstein's malformation.

Tricuspid valve pathology in Ebstein's malformation requires replacement when it is not possible to repair or reconstruct this valve. In smaller children, in whom the right-sided atrioventricular valve is severely dysplastic and right ventricular volume is prohibitive, prosthetic replacement is not always possible. We report here on 3 patients who underwent stentless semilunar homograft replacement (top-hat procedure) of tricuspid valve for Ebstein's anomaly with good short-term outcome. This provides an attractive alternative in the management of a certain difficult subset of patients, avoids long term anticoagulation and probably is more durable.

Successful orthotopic transplantation of a fresh tricuspid valve homograft in a human.

We report a successful transplantation of a human tricuspid valve in a human. We used a fresh tricuspid homograft with its chordae tendineae and papillary muscles, harvested 5 days earlier under sterile conditions from a multiorgan donor a few minutes after cardiectomy (the heart was not suitable for cardiac transplantation) and immediately stored at 4 degrees C. We elected to implant the homograft in a young heroin addict. Our experience demonstrates that the implantation of an atrioventricular homograft in the orthotopic position is technically feasible and can achieve good results, at least in the short term.

Clinical and hemodynamic assessment of the Angell-Shiley porcine xenograft.

Valve replacement with an Angell-Shiley bioprosthesis was accomplished in 449 patients. To evaluate the bioprostheses from this total series, 344 patients who did not undergo associated operation, had no previous operations, or had no other valve substitutes were selected. Hospital mortality was 2.6% for aortic (4 out of 156), 7.2% for mitral (9 out of 125), and 12.7% for multiple-valve replacements (8 out of 63). The 323 patients discharged from the hospital were followed for 6 to 36 months. There were 15 late deaths. Hepatitis, bleeding, thromboembolism, endocarditis, and residual valvular incompetence, always periprosthetic, were the major complications. Forty-five patients with single-valve replacement (16 mitral and 29 aortic) without clinical valve dysfunction were electively recatheterized to assess hemodynamic performance. Measurements were recorded at rest and during exercise on a bicycle ergometer. Functional aortic valve orifice averaged 1.23 +/- 0.33 cm2 and the mean systolic gradient was 21.51 +/- 6.68 mm Hg at rest. During exercise, aortic gradient increased to 26.60 +/- 7.54 mm Hg and mean functional area to 1.51 +/- 0.34 cm2. In the mitral position, the mean diastolic gradient at rest was 8.44 +/- 3.17 mm Hg and the functional orifice area averaged 1.67 +/- 0.51 cm2. Exercise increased the mean gradient to 11.92 +/- 3.8 mm Hg and the mean orifice area to 2.05 +/- 0.57 cm2.

Partial tricuspid valve transfer for repair of mitral insufficiency due to ruptured chordae tendineae.

BACKGROUND: A new technique is suggested for the reconstructive surgical treatment of mitral regurgitation. It involves partial transfer of the tricuspid valve of the patient to the mitral valve, in order to provide chordae to correct anterior leaflet prolapse of the mitral valve, secondary to rupture of the chordae tendineae. METHODS: From January 1991 to May 1997, 20 patients with mitral insufficiency due to rupture of the chordae were operated on. The prevailing cause was myxomatous degeneration (70%). Patients were in New York Heart Association functional class III and IV. RESULTS: There were no hospital deaths. Two patients were reoperated on. Eighteen patients (90%) are alive with their own valves (class I and II). Doppler echocardiogram mean values were: ejection fraction, 0.65; left atrial diameter, 4.2 cm; mitral area, 2.4 cm2; mitral transvalvular gradient, 3.3 mm Hg. No regurgitation or mild regurgitation was observed in 16 (94.1%) of the 17 cases evaluated. Mean tricuspid valvular area was 3.3 cm2. In all cases, no tricuspid regurgitation was present or it was mild. CONCLUSIONS: Partial transfer of the tricuspid valve to the mitral valve is an effective procedure for the surgical treatment of mitral valve insufficiency secondary to ruptured chordae tendineae of the anterior leaflet.

Tricuspid autograft for repair of a destroyed mitral commissure.

The study evaluated the results of the tricuspid valve autograft technique, consisting of transferring the posterior tricuspid leaflet and subvalvular apparatus towards the mitral valve to reconstruct a destroyed commissure. Twenty patients entered the study. Etiology was degenerative in 12 patients (mean age, 55 +/- 21 years). Nine patients had endocarditis, 8 were rheumatic. Echocardiography results and secondary events were reviewed. Mean follow-up was 44 +/- 17 months. One patient died from sepsis. Survivors were in sinus rhythm. Predischarge echocardiography showed trivial or no mitral regurgitation in all but one patient (mild). Mean transmitral gradients were 3 to 6 mm Hg, and valvular surface was 4.3 +/- 2.1 cm(2). On the tricuspid valve, regurgitation was zero to mild, gradients 4 to 7 mm Hg. One patient developed recurrent endocarditis at 18 months with moderate regurgitation. Results were stable in all the other patients. The tricuspid autograft is an attractive technique for a selected group of patients with commissural destruction. The 6-year results are very encouraging.

Transfer of the posterior leaflet of the tricuspid valve to the mitral valve.

BACKGROUND AND AIM OF THE STUDY: Coverage of large commissural defects may present a surgical challenge in mitral valve repair, for which the transfer of posterior tricuspid valve leaflet tissue is an attractive approach. METHODS: Five patients aged between 35 and 55 years underwent this procedure. After wide excision of the diseased mitral commissures, the posterior leaflet of the tricuspid valve was carefully checked, removed with its subvalvular apparatus, and transferred to the commissural area of the mitral valve. The stress on the papillary muscle suture was relieved by reinforcement of the free edge of the transferred leaflet by natural or artificial chordae. The tricuspid valve was repaired using either a sliding plasty or an annuloplasty. RESULTS: One patient who had no reinforcement of the subvalvular apparatus had a papillary muscle rupture and required mitral valve replacement during the early postoperative period. The four remaining patients remained asymptomatic and had no or trivial mitral regurgitation after a median of 13 months (range: 3-18 months), with excellent result at transesophageal echocardiography. CONCLUSION: We conclude that transfer of the tricuspid valve leaflet allows coverage of large commissural defect, and deserves a place among the surgeon's arsenal of reconstructive techniques for mitral valve repair.

Is the tricuspid position suitable for testing replacement bioprosthetic valves in the sheep model?

BACKGROUND AND AIM OF THE STUDY: Glutaraldehyde may promote calcification in xenograft tissue by the action of toxic aldehyde group residues involved in the cross-link process. Post-fixation treatment with homocysteic acid (HA) neutralizes this toxicity by bonding aldehyde groups, and enhances biocompatibility on the basis of strongly electronegative sulfonic groups. Previous studies in a rat subcutaneous model showed significant long-term mitigation of mineralization of glutaraldehyde-fixed pericardium treated with HA. This study aimed to assess the anticalcific efficacy of HA in a valvular implant in growing sheep, and establish if the tricuspid position is suitable for testing replacement bioprosthetic valves. METHODS: Eleven stented 25 mm Pericarbon bioprostheses (seven HA-treated, four standard) were implanted in the tricuspid position of growing sheep. Infective endocarditis occurred in four prostheses. Among the remaining seven, three (two HA-treated, one standard) were explanted at 91 days (mid-term), and four (two HA-treated, two standard) at 140-141 days (long-term). All explants were studied by gross, X-ray, light, transmission and scanning electron microscopy, as well as by atomic absorption spectroscopy. RESULTS: No histological and ultrastructural difference in tissue preservation were observed between HA-treated and standard Pericarbon bioprostheses, either in the mid or long term. The mean calcium content of mid-term HA-treated explants was 9.55 mg/g compared with 16.26 mg/g in mid-term standard explants. Only one late standard explant failed as a result of severe stenosis caused by massive dystrophic calcification. Among four late explants, two showed significant increase in mineralization (HA-treated, 87.45 mg/g; standard, 181.20 mg/g), while two showed calcium contents similar to those in mid-term explants (HA-treated, 11.96 mg/g; standard, 17.32 mg/g). CONCLUSION: Post-fixation treatment with HA preserves structural properties after tricuspid implantation in growing sheep. The tricuspid implant in the sheep model failed to reproduce remarkable accelerated progressive calcification in all xenografts so as to demonstrate a significant difference between HA and standard explants. The tricuspid position for testing replacement bioprosthetic valves should be abandoned, and investigations repeated with the prosthesis in the mitral position.

Mitral homograft in the tricuspid position, aortic homograft and mitral plasty in a drug addict with multiple valve endocarditis.

The case is reported of multiple valve surgery using as little prosthetic material as possible in a drug addict with recurrent right and left bacterial endocarditis. The patient underwent aortic valve replacement with a cryopreserved aortic homograft, mitral repair and tricuspid valve replacement with a mitral homograft, using a modified technique. The indications and surgical options for tricuspid valve endocarditis in this patient group are discussed, with particular focus on technical aspects of using mitral homografts in the tricuspid position.

Mitral valve repairs using the posterior tricuspid leaflet and chordae. Technique and results.

OBJECTIVE: Some mitral lesions are still out of reach of conventional repairs. Transferring the posterior leaflet of the tricuspid valve with its subvalvular apparatus to the mitral valve is a new autograft technique which has allowed us a conservative approach in cases where repair seemed less predictable. METHODS: After removing the posterior tricuspid leaflet with its subvalvular apparatus, the tricuspid autograft was inserted by implanting its papillary muscle onto the mitral papillary muscle and then by suturing the leaflet tissue in place. The tricuspid valve was subsequently repaired by annular plication and leaflet suture. A tricuspid ring was used in all but the first case. RESULTS: The age of the seven patients ranged from 20 to 70 years. Postoperative controls by transesophageal echocardiography showed no leaks in five and trivial in one on the site of the mitral repair. On the tricuspid valve, we found a moderate leak in the first case and trivial or none in the following cases, where a tricuspid ring was used. With a 3-12 month follow-up the results are stable. CONCLUSIONS: This autograft technique is reproducible, and extends the field of mitral valve repairs. Compared to segments of mitral homografts, we prefer the intraoperative availability of natural chordae and valvular leaflet that have no immunological interference. The patient is his own tissue bank and the tricuspid valve can be repaired with a very low risk of significant dysfunction.

Tricuspid bioprosthesis replacement with cryopreserved mitral homograft.

We report the case of replacement of a dysfunctional tricuspid Hancock bioprosthesis by a cryopreserved mitral homograft. Tricuspid bioprosthesis was approached on a beating heart. The mitral homograft was orientated so as the anatomic anterior leaflets corresponding and a semi rigid prosthetic ring was inserted. At 1 year follow-up, the patient's clinical condition and echocardiographic results were satisfactory.

Surgical repair for degenerative and rheumatic mitral valve disease. Operative and mid-term results.

BACKGROUND: Non randomized studies suggest that mitral valve repair for rheumatic disease is technically more difficult than repair for degenerative disease, and that operative and late results are worse. New surgical techniques have been developed in our and other institutes during the last 5 years, and this moved us to review the experience with these two pathologies and to compare the operative and mid-term METHODS: From March 1996 to September 1997, 66 patients underwent primary mitral valve repair for treatment of degenerative or rheumatic disease. Fifty-two patients (79%) were in the former group (group A) and 14 in the latter (group B). Surgery was performed by 2 experienced cardiac surgeons. A new technique to calculate the exact artificial chordae length was introduced. In 2 cases, tricuspid autografts were transposed to mitral position and reinforced with artificial chordae. Patients were followed both clinically and echocardiographically. The follow-up data were collected in a 1-month period (May 2000). The average clinical follow-up was 3.1+/-0.9 years (range 1.7 to 4.2 years) while the average echocardiographic follow-up was 2.7+/-0.7 years (range 9 months to 4 years). All values were expressed by means of the average and standard deviation. chi(2) and Student's "t"-test were used to analyze the significance between variables. The Kaplan-Meyer method was used for actuarial statistics. RESULTS: There were no operative deaths in either group. In group A, 1 patient underwent a second surgical repair 1 week later, successfully. In group B no patients underwent reoperation within 30 days or during the initial hospitalization. At follow-up of group A there were the following events: deaths from cancer (n=2), endocarditis (n=1), aortic dissection (n=1). At follow-up of group B there were mitral valve replacement (1 year after first operation, n=1), Ross procedure (n=1), ischemic heart failure (n=1). Among the remaining 62 patients followed, 32 were in NYHA class I, 15 in class II, 3 in class III, and none in class IV, in group A. In group B, 7 patients were in class I, 4 in class II, 1 in class III and none in class IV (p=ns). In group A mitral regurgitation was absent in 23 patients, mild in 21, moderate in 6, while in group B it was absent in 4, mild in 6, and moderate in 2 (p=ns). In both groups there were no cases of severe insufficiency. The mean gradient was 1.1+/-1.7 mmHg in group A (median=0), and 2.4+/-3.1 mmHg in group B (median=0), (p=ns). No case of systolic anterior movement was seen at mid-term. The event free-survival rate was 92.8% in group A and 92.3% in B. CONCLUSIONS: Perfecting and innovation of surgical techniques make possible nowadays to reach good and equivalent operative and mid-term results in both pathologies.