Performance of allografts and xenografts for right ventricular outflow tract reconstruction

Valved Conduits for Right Ventricular Outflow Tract Reconstruction: A Review of Current Technologies and Future Directions

The need for right ventricular outflow tract reconstruction is common and growing in congenital heart surgery given expanding indications for the repair of congenital as well as acquired heart disease. Various valved conduit options currently exist including homografts, xenograft pulmonary valved conduits (Contegra™), and porcine valved conduits. The major limitation for all conduits is implant durability, which requires reoperation. Currently, cryopreserved homografts are often used given their superiority shown in long-term data. Significant limitations remain in the cost and availability of the graft, particularly for smaller sizes. Contegra conduits are available in a variety of sizes. Nonetheless, the data regarding long-term durability are less robust and studies comparing durability with homografts have been conflicting. Additionally, there is concern for increased rates of late endocarditis in this conduit. Porcine valved conduits offer a reliable option but are limited by structural valve degeneration associated with all types of bioprosthetic heart valve replacements. New developments in the field of tissue engineering have produced promising bio-restorative valved conduits that may overcome many of the limitations of previous conduit technologies. These remain in the early stages of clinical testing. This review summarizes the clinical data surrounding the conduits used most commonly in clinical practice today and explores emerging technologies that may bring us closer to developing the ideal conduit.

Tissue Engineered Transcatheter Pulmonary Valved Stent Implantation: Current State and Future Prospect

Patients with the complex congenital heart disease (CHD) are usually associated with right ventricular outflow tract dysfunction and typically require multiple surgical interventions during their lives to relieve the right ventricular outflow tract abnormality. Transcatheter pulmonary valve replacement was used as a non-surgical, less invasive alternative treatment for right ventricular outflow tract dysfunction and has been rapidly developing over the past years. Despite the current favorable results of transcatheter pulmonary valve replacement, many patients eligible for pulmonary valve replacement are still not candidates for transcatheter pulmonary valve replacement. Therefore, one of the significant future challenges is to expand transcatheter pulmonary valve replacement to a broader patient population. This review describes the limitations and problems of existing techniques and focuses on decellularized tissue engineering for pulmonary valve stenting.

[First serial transcatheter implantation of pulmonary valve using MedLab-KT prosthesis]

BACKGROUND

Surgical treatment of 'blue' congenital heart defects frequently implies various interventions on the outlet portion of the right ventricle or pulmonary artery trunk. Most often used are various conduits, reconstructing the outlet portion of the right ventricle and pulmonary artery. Most patients having previously endured the mentioned interventions, would in the remote terms require repeat operative procedures for stenosis or insufficiency on the pulmonary valve or the implanted conduit. Taking into account complexity and the risk of open interventions, the current trends are towards more frequent use of transcatheter implantation of the pulmonary valve.

AIM

The purpose of this work is to present the first serial experience with hybrid transventricular implantation of an original Russian-made valve into the position of the pulmonary artery.

PATIENTS AND METHODS

We retrospectively studied a series of 5 clinical cases who from July 2019 to May 2020 at the Federal Centre of Cardiovascular Surgery (Penza) had underwent hybrid transventricular implantation of the first Russian-made valve-containing stent (MedLab-KT) into the position of the pulmonary valve, with the stent's closing component consisting of leaflets made of polytetrafluoroethylene.

RESULTS

3 patients underwent implantation of valve # 25 and 2 subjects received valve # 23, with all cases yielding good immediate results. The haemodynamic parameters of the implanted prosthesis were optimal. In all cases, the significant gradient was absent and regurgitation did not exceed grade I. There was no in-hospital mortality. The method of hybrid prosthetic repair of the pulmonary valve via the transapical right-ventricular access from the left lateral mini-thoracotomy was aimed at reducing potential risks of artificial circulation, also contributing to a significant decrease in the traumatic nature of surgical treatment of patients requiring a repeat intervention for pulmonary valve pathology.

High incidence of fever in patients after biointegral pulmonic valved conduit implantation

OBJECTIVE

To describe our short- and medium-term outcomes using the BioIntegral pulmonic conduit.

METHODS

Between August 2018 and September 2019, the BioIntegral pulmonic valved conduit was used for right ventricular outflow tract reconstruction in 48 patients. The data were retrospectively retrieved from the patient charts.

RESULTS

The median age at surgery was 36 months (interquartile range [IQR] = 18-62 months). The diagnoses were pulmonary atresia-ventricular septal defect in 28 patients, absent pulmonary valve in four patients, truncus arteriosus in six patients, TGA-VSD-PS in five patients, conduit stenosis in three patients, and left venticular outflow tract obstruction requiring a Ross operation in two patients. In the postoperative short-term follow-up, 15 patients out of 48 had a high fever. Of these, 12 patients had concomitantly elevated C-reactive protein levels. There were no patients with blood culture positivity. The median postoperative length of hospital stay was 14 days (IQR = 8-21 days). The overall mortality was 4% in two patients, one died of right ventricular failure and multiple organ failure and one died of pulmonary embolism. The two patients who died were not among the 15 patients with fever. However, four patients with fever underwent balloon angioplasty for conduit restenosis in their medium-term follow-up.

CONCLUSION

There was a high incidence of fever and adverse outcomes in the short-term postoperative follow-up of patients in whom the BioIntegral pulmonic valved conduit was implanted. Caution is advisable in using these conduits until there is convincing evidence about the sterilization and storage standards of these grafts.

Comparison of half-turned truncal switch and conventional operations

 

OBJECTIVES

To compare conventional procedures with the half-turned truncal switch operation (HTTSO) for the management of complete transposition of the great arteries with left ventricular outflow tract (LVOT) obstruction using time-resolved 3-dimensional magnetic resonance phase-contrast imaging.

METHODS

We identified 2 cases that underwent the Rastelli procedure and one case that underwent the Réparation a l'étage ventriculaire before 2002 [conventional procedures group (group C)], and 16 cases of HTTSO that were performed between 2002 and 2020 [HTTSO group (group H)]. Postoperative haemodynamics were assessed using time-resolved 3-dimensional magnetic resonance phase-contrast imaging in cases in both groups.

RESULTS

The median follow-up period was 20.4 years in group C, and 6.1 years in group H. In group C, all 3 patients underwent reoperation because of postoperative right ventricular outflow tract obstruction and/or insufficiency. In addition, permanent pacemaker implantation was needed in 1 patient because of complete atrioventricular block complicated by ventricular septal defect enlargement. In group H, reoperation for LVOT/right ventricular outflow tract obstruction was not needed. A time-resolved 3-dimensional magnetic resonance phase-contrast imaging examination revealed high energy loss and wall shear stress in the winding LVOT in the group C. In contrast, low energy loss and wall shear stress, with straight and smooth LVOT, were identified in group H.

CONCLUSIONS

HTTSO was shown to be superior to conventional procedures because a straight and wide LVOT could be obtained. Therefore, HTTSO should be the first choice for complete transposition of the great arteries with LVOT obstruction.

Screening for potential targets to reduce stenosis in bioprosthetic heart valves

Progressive stenosis is one of the main factors that limit the lifetime of bioprosthetic valved conduits. To improve long-term performance we aimed to identify targets that inhibit pannus formation on conduit walls. From 11 explanted, obstructed, RNAlater presevered pulmonary valved conduits, we dissected the thickened conduit wall and the thin leaflet to determine gene expression-profiles using ultra deep sequencing. Differential gene expression between pannus and leaflet provided the dataset that was screened for potential targets. Promising target candidates were immunohistologically stained to see protein abundance and the expressing cell type(s). While immunostainings for DDR2 and FGFR2 remained inconclusive, EGFR, ErbB4 and FLT4 were specifically expressed in a subset of tissue macrophages, a cell type known to regulate the initiation, maintenance, and resolution of tissue repair. Taken toghether, our data suggest EGFR, ErbB4 and FLT4 as potential target candidates to limit pannus formation in bioprosthestic replacement valves.

Long-Term Comparison Between Pulmonary Homograft Versus Bioprosthesis for Pulmonary Valve Replacement in Tetralogy of Fallot

Background

Tetralogy of Fallot repair results in late occurrence of pulmonary regurgitation, which requires pulmonary valve replacement in a large proportion of patients. Both homografts and bioprostheses are used for pulmonary valve replacement as uncertainty remains on which prosthesis should be considered superior. We performed a long‐term imaging and clinical comparison between these 2 strategies.

Methods and Results

We compared echocardiographic and clinical follow‐up data of 209 patients with previous tetralogy of Fallot repair who underwent pulmonary valve replacement with homograft (n=75) or bioprosthesis (n=134) between 1995 and 2018 at a tertiary hospital. The primary end point was the composite of pulmonary valve replacement reintervention and structural valve deterioration, defined as a transpulmonary pressure decrease ≥50 mm Hg or pulmonary regurgitation degree of ≥2. Mixed linear model and Cox regression model were used for comparisons. Echocardiographic follow‐up duration was longer in the homograft group (8 [interquartile range, 4–12] versus 4 [interquartile range, 3–6] years; P<0.001). At the latest echocardiographic follow‐up, homografts showed a significantly lower transpulmonary systolic pressure decrease (16 [interquartile range, 12–25] mm Hg) when compared with bioprostheses (28 [interquartile range, 18–41] mm Hg; mixed model P<0.001) and a similar degree of pulmonary regurgitation (degree 0‐4) (1 [interquartile range, 0–2] versus 2 [interquartile range, 0–2]; mixed model P=0.19). At 9 years, freedom from structural valve deterioration and reintervention was 81.6% (95% CI, 71.5%–91.6%) versus 43.4% (95% CI, 23.6%–63.2%) in the homograft and bioprosthesis groups, respectively (adjusted hazard ratio, 0.27; 95% CI, 0.13–0.55; P<0.001).

Conclusions

When compared with bioprostheses, pulmonary homografts were associated lower transvalvular gradient during follow‐up and were associated with a significantly lower risk of reintervention or structural valve degeneration.

Right ventricular outflow tract obstruction: a quest for ideal management

Management of right ventricular outflow tract obstruction has undergone much change over the last century. Techniques described in the literature include anatomical repairs and the use of various patches, conduits, and innovative grafts. However, many of these approaches require reoperations or catheter-based interventions, leading to increased morbidity, mortality, and cost. The search for the ideal long-lasting conduit continues and there are new techniques on the horizon, using genetic engineering and nanotechnology. This review discusses the evolution of various techniques for repair of right ventricular outflow tract obstruction, past and current conduits, as well as ongoing research.

Early Results of Valved Bovine Jugular Vein Conduit for Right Ventricular Outflow Tract Reconstruction

Objective

Many congenital cardiac anomalies present with accompanying severe right ventricular outflow tract (RVOT) obstruction or interruption requiring surgical correction. RVOT reconstruction by means of a conduit is often necessary in the majority of these patients in the early years of life and there are several proposed conduits for this purpose.

Methods

Fourteen patients with different congenital cardiac pathologies underwent RVOT reconstruction with the newly developed bovine valved jugular vein conduit (The Contegra conduit). The function of the conduit is observed by echocardiographic examinations at the hospital discharge and at follow-up visits with special attention to the function of the venous valve and to any gradient on the RVOT.

Results

There were two perioperative mortalities. All the surviving patients are followed for a mean period of 8.07 months (range 2 to 33 months). The function of the venous valve was determined, in 4 patients (33.33%) as without regurgitation, in 7 patients (58.3%) as mild regurgitation and in 1 patient (8.33%) as mild-to-moderate regurgitation. The reconstructed RVOT was free of any significant gradient at the hospital discharge (mean 10.83 ±10.18 mmHg) and at the follow-ups (mean 12.916 ±12.33 mmHg). There was not a trend towards an increase in the gradients following discharge.

Conclusion

The early results of the Contegra valved conduit are very satisfactory. This graft can be a good alternative for RVOT reconstruction, particularly in the neonatal and infant patient group. These patients can be managed by homograft replacement of their conduit in later years.

Late results of right ventricular outflow tract reconstruction with a bicuspid expanded polytetrafluoroethylene valved conduit

BACKGROUND AND AIM TO READ

We report the results of a bicuspid expanded polytetrafluoroethylene (ePTFE) valved conduit used for right ventricular outflow tract reconstruction (RVOTR).

METHODS

Between November 2005 and February 2009, 12 conduits were used for RVOTR. The mean age and weight of patients were 43.5 ± 46.4 months and 13.4 ± 8.6 kg. The main diagnosis was tetralogy of Fallot with pulmonary atresia in eight patients. The most common conduit size was 18 mm. The mean follow-up was 88.0 ± 35.9 months.

RESULTS

There were no operative and late mortalities. At discharge, the mean peak systolic pressure gradient across the RVOT was 14.1 ± 11.3 mmHg. There was no conduit valve regurgitation in nine patients. At the latest echocardiography (mean follow-up: 84.3 ± 35.5 months), the mean peak systolic pressure gradient across the RVOT was 59.7 ± 20.2 mmHg, and there was no conduit valve regurgitation in six patients. Freedom from conduit malfunction was 100% and 83.3%, at 1 and 8 years, respectively. Two conduits were explanted due to sternal compression and four from conduit malfunction. Freedom from explantation was 83.3% and 74.2% at 2 and 8 years, respectively.

CONCLUSIONS

ePTFE bicuspid valved conduit has good late function in terms of valve regurgitation, but the pressure gradient across the conduit increases with time, which is the main cause of conduit failure and explantation.

Multiply adjusted comparisons: A meta-analysis method to compare single-arm clinical-trial data to literature results regarding a competitor

Prospective randomized controlled trials are difficult to obtain if a promising new therapy has to be tested against seemingly obsolete alternatives. One method to address this problem is to compare the results of (multicentre) trials to literature results. However, previous treatment-era changes and population-dependent results complicate objective comparisons. The presented approach describes a method to objectify such comparisons in cases in which individual raw data regarding a new therapy have to be compared to summary results regarding a conventional alternative published in the literature. The chosen example is the introduction of bovine neck veins as a substitute for dysfunctional human pulmonary valves, and the conventional therapeutic alternative is pulmonary-artery homografts. Literature research, subgroup identification, filtering, endpoint remodelling, weighting and, if necessary, confidence-limit calculation yield adjusted comparisons. These individual comparisons are then aggregated, first by article and then over several articles (similar to meta-analyses), resulting in a differentiated panel of answers (Multiply Adjusted Comparisons). In situations in which extensive raw data regarding a new therapeutic alternative but no randomized controlled trials and no raw data from previous studies using the conventional therapeutic alternative are available, the proposed method identifies the best evidence and is by far superior to unadjusted direct comparisons or gut feelings.

Percutaneous pulmonary valve implantation - state of the art and Polish experience

Percutaneous pulmonary valve implantation (PPVI) is a relatively new method of treating patients with right ventricular outflow tract (RVOT) dysfunction after surgical repair of congenital heart disease. Since its introduction in 2000 by Bonhoeffer, more than ten thousand PPVI procedures have been performed worldwide. Indications for PPVI have been adapted from those accepted for surgical intervention. Two types of valves are being used: Melody Medtronic available in diameters 16 mm and 18 mm and the family of Edwards SAPIEN valves 23, 26 and 29. The procedure has been shown to be feasible and safe when performed in patients with full pulmonary conduit dysfunction and in selected cases of patched RVOT. The low complication rate and the reduced number of open-chest re-interventions over a patient’s lifetime are among the main advantages of the procedure. The most important problem responsible for late mortality and reinterventions is infective endocarditis. Size restrictions of the currently available valves limit deployment in the majority of patients with a wide RVOT. Newer devices are being developed to make these patients suitable for PPVI. A literature review, Polish experience and results of PPVI performed in 66 patients in the Institute of Cardiology in Warsaw are briefly reported.

Durability of down-sized homografts for the reconstruction of the right ventricular outflow tract

OBJECTIVES

Small-sized homografts are rare but may be required for the reconstruction of the right ventricular outflow tract (RVOT). Down-sizing adult-sized homografts can be an option to overcome the shortage of availability.

METHODS

Since 1994, we have been down-sizing adult-sized homografts by excising one cusp. The aim of the study was to analyse the durability of down-sized homografts and compare it with small-sized homografts in a paediatric population. All patients below a body weight of 14 kg were included in the study. The end-point of the study was homograft failure.

RESULTS

A total of 152 patients met the inclusion criteria of the study, of which 82 patients (54%) received a down-sized homograft. The median age was 17.1 (0.3-64.8) months and the mean weight 8.4 ± 3.4 kg. Fifty-eight patients (38%) were under 1 year and 10 (6.5%) under 1 month of age at the time of homograft implantation. The mean homograft size of the whole study population was 14.7 ± 2.5 mm and the mean z-score was 1.6 ± 0.9. The median follow-up time was 10 (0.03-19.7) years. Early mortality after homograft implantation was 5% (n = 8), 4 of these patients had received a down-sized homograft. The study population comprised early survivors, that is, 144 patients. During follow-up, a total of 46 homografts failed, 23 in each group, after a mean time of 5.7 ± 4.2 years. Freedom from homograft failure was 94.6 ± 2.6, 87.2 ± 4 and 68.6 ± 6.6% for down-sized homografts and 95.2 ± 2.7, 78.7 ± 5.5 and 61 ± 7% for small-sized homografts at 1, 5 and 10 years, respectively (P = 0.3). Risk factors for homograft failure in the multivariable analysis were a homograft z-score of <1 and age below 1 year at the time of implantation (P = 0.02).

CONCLUSION

Down-sized homografts demonstrated a durability similar to that of small-sized homografts. Therefore, down-sizing adult-sized homografts by creating a bicuspid valve to fit into the corresponding RVOT in children with congenital heart defects is an excellent method to overcome the shortage of small-sized homografts.

Current status of right ventricular outflow tract reconstruction: complete translation of a review article originally published in Kyobu Geka 2014;67:65-77

Right ventricular outflow tract (RVOT) reconstruction is becoming more prevalent as the number of adult patients who require repeated surgery long after definitive repair of congenital heart defects during childhood has increased. Early primary repair and annulus-preserving surgery have been the two current strategies of RVOT reconstruction from the viewpoint of timing and indications for surgical intervention; however, the long-term outcomes of both procedures remain unknown. Although various materials have been used for pulmonary valve replacement during RVOT reconstruction, deficient durability due primarily to immunological rejection frequently arises, particularly when implanted into young patients. A multicenter study in Japan showed that the clinical outcomes of expanded polytetrafluoroethylene (ePTFE) valved patches/conduits that we developed and manufactured comprised an excellent alternative material for RVOT reconstruction. Such enhanced outcomes might have partly been attributable to the biocompatibility and low antigenicity of ePTFE, and also to the fluid dynamic properties arising from the structural characteristics of a bulging sinus and a fan-shaped valve. However, numerous issues concerning RVOT reconstruction, such as indications for and the timing of definitive repair, as well as the choice of materials for pulmonary valve replacement, must be resolved to achieve better patient prognoses and quality of life. This review describes recent surgical strategies and outstanding issues associated with RVOT reconstruction.

Melody ® transcatheter pulmonary valve implantation: results from a French registry

BACKGROUND

Percutaneous implantation of pulmonary valves has recently been introduced into clinical practice.

AIM

To analyse data of patients treated in France between April 2008 and December 2010.

METHODS

Prospective, observational, multi-centric survey by means of a database registry of the Filiale de cardiologie pédiatrique et congénitale.

RESULTS

Sixty-four patients were included, with a median (range) age of 21.4 (10.5-77.3) years. The majority (60.9%) of the patients were New York Heart Association (NYHA) class II. The most common congenital heart disease was tetralogy of Fallot with or without pulmonary atresia (50%). Indication for valve implantation was stenosis in 21.9%, regurgitation in 10.9% and association of stenosis and regurgitation in 67.2%. Implantation was successful in all patients. Pre-stenting was performed in 96.9% of cases. Median (range) procedure time was 92.5 (25-250) minutes. No significant regurgitation was recorded after the procedure, and the trans-pulmonary gradient was significantly reduced. Early minor complications occurred in five cases (7.8%). Three patients died during a median follow-up of 4.6 (0.2-5.2) years, two from infectious endocarditis and one from end-stage cardiac failure. Surgical reintervention was required in three patients. Follow-up with magnetic resonance imaging demonstrated significant improvements in right ventricular volumes and pulmonary regurgitation in mixed and regurgitant lesions.

CONCLUSIONS

Transcatheter pulmonary valve implantation is highly feasible and mid-term follow-up demonstrates sustained improvement of right ventricular function. Late endocarditis is of concern, therefore longer follow-up in more patients is urgently needed to better assess long-term outcome.

CLINICAL TRIAL REGISTRATION

NCT01250327.

Early and 1-year outcome and predictors of adverse outcome following monocusp pulmonary valve reconstruction for patients with tetralogy of Fallot: A prospective observational study

Background and Objectives:

Repair of tetralogy of Fallot (TOF) with monocusp pulmonary valve reconstruction prevents pulmonary regurgitation (PR) for a variable period. Since postoperative outcome is governed by PR and right ventricular function, we sought to assess the severity of pulmonary regurgitation and right ventricular outflow (RVOT) gradient in the immediate postoperative period and at 1 year and attempted to identify the anatomical substrates responsible for adverse outcomes.

Methods:

The study included 30 patients. Transthoracic echocardiography was performed before surgery, within 5 days of surgery, and 1 year later. Presence and severity of PR, RVOT gradient, and residual branch pulmonary stenosis were assessed. Right ventricular and monocusp valve functions were studied.

Results:

Median age was 36.5 months (3-444 months). There were no deaths. Pulmonary regurgitation was mild in 18, moderate in 10, and severe in 2 patients immediately following surgery. At 1 year, 10 patients had severe PR and one had significant RVOT gradient. None of the variables like age, presence of supravalvar pulmonary branch stenosis, main pulmonary artery diameter, or mobility of monocusp valve was found to have any significant association with the progression of PR. McGoon index <1.5 showed a trend toward more PR, while patients with more residual RVOT gradient had lesser regurgitation.

Conclusions:

Repair of TOF with monocusp pulmonary valve reduces immediate postoperative PR. At 1 year, the monocusp valve underwent loss of function in a significant proportion and PR also progressed. This study could not identify any predictors of progression of PR, though patients with McGoon index <1.5 tended to have more PR while those with more outflow gradient had lesser PR.

Which type of conduit to choose for right ventricular outflow tract reconstruction in patients below 1 year of age?†

OBJECTIVES

Reconstruction of the right ventricular outflow tract (RVOT) with a conduit in patients below 1 year of age remains a matter of concern due to limited availability and durability of conduits. We sought to analyse the freedom from conduit exchange in this subgroup of patients by comparing different conduits.

METHODS

Data of 145 consecutive patients below 1 year of age, requiring a conduit for RVOT reconstruction between 1994 and 2011 were reviewed. The endpoints of the study were defined as: 'conduit exchange for any reason', 'at least moderate conduit stenosis' and 'at least moderate insufficiency'.

RESULTS

Homografts, bovine jugular vein conduits (Contegra) and porcine-valved Dacron conduits (Hancock) were implanted in 62 (43%), 35 (24%) and 48 (33%) patients, respectively. The mean conduit diameter was 12.9 ± 1.3 mm. A conduit exchange was necessary in 72 patients (55%) at a median time of 5.9 years [1.1-10.8]. The rate of freedom from conduit exchange at 5 years was 69.4 ± 6.6, 59.4 ± 8.7 and 53.8 ± 7.4%, respectively (P = 0.4). The rate of freedom from at least moderate stenosis was 85.4 ± 5.6, 75.1 ± 9.1 69.1 ± 7.9% at 5 years and 59.2 ± 11.1, 35.8 ± 12.0, 49.7 ± 10.1% at 10 years, for homografts, Contegra and Hancock conduits, respectively. The rate of freedom from at least moderate conduit insufficiency was 91.7 ± 4, 74.6 ± 9.1, 86.9 ± 7.4% at 5 years and 64.8 ± 14.1, 44.2 ± 13.7, 52.1 ± 14.2% at 10 years, for homografts, Contegra and Hancock conduits, respectively. Patients with a Contegra conduit developed moderate conduit stenosis or insufficiency faster than patients with a homograft (P = 0.01). Age below 1 month and heterotopic implantation of the conduit emerged as risk factors for conduit exchange in the univariate analysis (P = 0.05, P = 0.02, respectively). There was no significant influence of the conduit type, conduit size, z-score or the body surface area. In the multivariate analysis, heterotopic implantation emerged as the only risk factor for conduit exchange (P = 0.02, hazard ratio = 1.6, 95% confidence interval = 1.0-2.7).

CONCLUSIONS

Homografts, bovine jugular vein conduits and porcine-valved Dacron conduits exhibit equal durability after implantation in patients below 1 year of age independent of their size. Nonetheless, moderate conduit stenosis or insufficiency develops earlier in patients with a Contegra conduit. Conduit placement in the neonatal period and implantation in a heterotopic position shortens the durability.

Bovine valved jugular vein (Contegra™) to reconstruct the right ventricular outflow tract

The right ventricular outflow tract (RVOT) is the part of the circulation located between the right ventricle and the bifurcation of the pulmonary artery. The most cranial part of the right ventriculum infundibulum, the pulmonary anulus, the valve and finally the main trunk of the pulmonary artery are the most important structures. The RVOT is frequently affected in congenital heart diseases, either isolated, or in combination with other cardiac malformations. Current techniques for surgical correction of anomalies of the RVOT include repair and/or replacement of the pulmonary valve often combined with sub- or supravalvular reconstruction. The use of extracardiac conduits (homografts, stented or stentless xenografts) to re-establish continuity between the pulmonary ventricle and pulmonary artery has been an important advance in repair of complex congenital malformations. The Contegra (Medtronic) conduit was introduced as a xenograft tissue for RVOT reconstruction. This conduit has some advantages over homografts including availability for pediatric and adult patient sizes and proximal and distal cuffs allowing for extended reconstruction. The principal late problem related to extracardiac conduit operations is the inevitable need for one or more conduit replacements due to patient somatic growth or progressive conduit degeneration and calcification leading to stenosis.

"V-PLASTY": a novel technique to reconstruct pulmonary valvular and annular stenosis in patients with right ventricular outflow tract obstruction

BACKGROUND

The goal of repair of right ventricular outflow tract obstruction with or without Tetralogy of Fallot (TOF) is to eliminate valvular and/or subvalvular obstruction. However, this operation has a high risk of late complication of pulmonary insufficiency. In this study, we aimed to present early period results of our new technique that we call "V-Plasty" developed to prevent pulmonary insufficiency after pulmonary valve reconstruction in selected patients.

METHODS

Between January 2006 and January 2010, we performed V-plasty for pulmonary valve reconstruction in 10 patients. Eight patients (5 males, 3 females) had TOF and 2 patients (1 male, 1 female) had atrial septal defect concomitant with pulmonary valve stenosis. Patient selection for V-plasty reconstruction was made due to the pulmonary valve anatomy and degree of stenosis. The mean follow-up time was 55.7 ± 16.2 months (ranging from 32 to 80 months).

RESULTS

Functional capacity of the patients improved immediately after the surgery. There were no mortality and re-operation in follow-up period. Patients were followed up with echocardiography one week after the operation, at 1st, 6th, 12th months and annually. There was no pulmonary insufficiency.

CONCLUSIONS

Operative correction of the pulmonary outflow tract obstruction with or without TOF, frequently requires transannular enlargement because of the infundibular and/or annular-valvular obstruction. This conventional technique is usually a reason for late pulmonary insufficiency. In our study, we have not seen pulmonary insufficiency in early term follow-up period. Our early term results are encouraging, but long term follow-up results are needed with large case series.

The Contegra conduit: Late outcomes in right ventricular outflow tract reconstruction

OBJECTIVES

To report the clinical outcomes (early death, late death, and rate of reintervention) and performance of the Contegra conduit as a right ventricle outflow tract implant and to determine the risk factors for early reintervention.

METHODS

Forty-nine Contegra conduits were implanted between January 2002 and June 2009. Data collection was retrospective. The mean age and follow-up duration of Contegra recipients was 3.5 ± 4.6 years and 4.2 ± 2.0 years, respectively.

RESULTS

There were three deaths (two early, one late), giving a survival rate of 93.9%. The rate of conduit-related reintervention was 19.6% and was most often due to distal conduit stenosis. Age at implantation of <3 months, receipt of a conduit of 12-16 mm diameter, and a diagnosis of truncus arteriosus were each significant contributors to the rate of reintervention.

CONCLUSION

The Contegra is a cost-effective and readily available solution. However, there is a limited range of larger calibers, which means that the homograft conduit (>22 mm) remains the first choice of implant in older children. The rates of reintervention are significantly higher with a diagnosis of truncus arteriosus, age at implantation of <3 months, and implantation of conduits sized 12-16 mm.

Tolerance to incompatible ABO blood group antigens is not observed following homograft implantation

Failure to develop antibodies to nonself A and B blood group antigens is well described after infant ABO-incompatible heart transplantation and suggests that exposure to incompatible ABO antigens early in life may lead to tolerance rather than immunogenicity. If this finding is also true following ABO-incompatible cryopreserved homograft implantation, then such patients who require transplantation may be able to accept certain ABO-incompatible organs. In this study, we measured anti-A and -B antibody titers (isohemagglutinins) and allosensitization to human leukocyte antigens (HLA) in 21 patients after homograft placement (12 of whom were <1 year of age at initial homograft exposure) in childhood. We also examined homograft explant specimens for endothelial preservation and expression of HLA and A and B blood group antigens. We observed no differences in isohemagglutinins between patients who received ABO-incompatible versus ABO-compatible homografts. Allosensitization to HLA was present in 88% of patients (9 of 9 ABO-incompatible recipients and 5 of 7 ABO-compatible recipients). In 7 homograft explant specimens (median implant duration 10.1 years), the vasa vasorum endothelium was intact with ABO blood group antigen expression on 3 of 5 non-O homografts. These data suggest that tolerance to incompatible A and B blood group antigens does not occur following placement of ABO-incompatible homografts in childhood.

Long term results of right ventricular outflow tract reconstruction with homografts

Background

Homograft cardiac valves and valved-conduits have been available in our institute since 1992. We sought to determine the long-term outcome after right ventricular outflow tract (RVOT) reconstruction using homografts, and risk factors for reoperation were analyzed.

Materials and Methods

We retrospectively reviewed 112 patients who had undergone repair using 116 homografts between 1992 and 2008. Median age and body weight at operation were 31.2 months and 12.2 kg, respectively. The diagnoses were pulmonary atresia or stenosis with ventricular septal defect (n=93), congenital aortic valve diseases (n=15), and truncus arteriosus (N=8). Mean follow-up duration was 79.2±14.8 months.

Results

There were 10 early and 4 late deaths. Overall survival rate was 89.6%, 88.7%, 86.1% at postoperative 1 year, 5 years and 10 years, respectively. Body weight at operation, cardiopulmonary bypass (CPB) time and aortic cross-clamping (ACC) time were identified as risk factors for death. Forty-three reoperations were performed in thirty-nine patients. Freedom from reoperation was 97.0%, 77.8%, 35.0% at postoperative 1 year, 5 years and 10 years respectively. Small-sized graft was identified as a risk factor for reoperation.

Conclusion

Although long-term survival after RVOT reconstruction with homografts was excellent, freedom from reoperation was unsatisfactory, especially in patients who had small grafts upon initial repair. Thus, alternative surgical strategies not using small grafts may need to be considered in this subset.

Percutaneous pulmonary valve implantation: two-centre experience with more than 100 patients

AIMS

Dysfunction of valved conduits in the right ventricular outflow tract (RVOT) limits durability and enforces repeated surgical interventions. We report on our combined two-centre experience with percutaneous pulmonary valve implantation (PPVI).

METHODS AND RESULTS

One hundred and two patients with RVOT dysfunction [median weight: 63 kg (54.2-75.9 kg), median age: 21.5 years (16.2-30.1 years), diagnoses: TOF/PA 61, TAC 14, TGA 9, other 10, AoS post-Ross-OP 8] were scheduled for PPVI since December 2006. Percutaneous pulmonary valve implantation was performed in all patients. Pre-stenting of the RVOT was done in 97 patients (95%). The median peak systolic RVOT gradient decreased from 37 mmHg (29-46 mmHg) to 14 mmHg (9-17 mmHg, P < 0.001) and the ratio RV pressure/AoP decreased from 62% (53-76%) to 36% (30-42%, P < 0.0001). The median end-diastolic RV-volume index (MRI) decreased from 106 mL/m(2) (93-133 mL/m(2)) to 90 mL/m(2) (71-108 mL/m(2), P = 0.001). Pulmonary regurgitation was significantly reduced in all patients. One patient died due to compression of the left coronary artery. The incidence of stent fractures was 5 of 102 (5%). During follow-up [median: 352 days (99-390 days)] one percutaneous valve had to be removed surgically 6 months after implantation due to bacterial endocarditis. In 8 of 102 patients, a repeated dilatation of the valve was done due to a significant residual systolic pressure gradient, which resulted in a valve-in-valve procedure in four.

CONCLUSION

This study shows that PPVI is feasible and it improves the haemodynamics in a selected patient collective. Apart from one coronary compression, the rate of complications at short-term follow-up was low. Percutaneous pulmonary valve implantation can be performed by experienced interventionalists with similar results as originally published. The intervention is technically challenging and longer clinical follow-up is needed.

Major adverse cardiac and cerebrovascular events after the Ross procedure: a report from the German-Dutch Ross Registry

BACKGROUND

The purpose of the study is to report major cardiac and cerebrovascular events after the Ross procedure in the large adult and pediatric population of the German-Dutch Ross registry. These data could provide an additional basis for discussions among physicians and a source of information for patients.

METHODS AND RESULTS

One thousand six hundred twenty patients (1420 adults; 1211 male; mean age, 39.2±16.2 years) underwent a Ross procedure between 1988 and 2008. Follow-up was performed on an annual basis (median, 6.2 years; 10 747 patient-years). Early and late mortality were 1.2% (n=19) and 3.6% (n=58; 0.54%/patient-year), respectively. Ninety-three patients underwent 99 reinterventions on the autograft (0.92%/patient-year); 78 reinterventions in 63 patients on the pulmonary conduit were performed (0.73%/patient-year). Freedom from autograft or pulmonary conduit reoperation was 98.2%, 95.1%, and 89% at 1, 5, and 10 years, respectively. Preoperative aortic regurgitation and the root replacement technique without surgical autograft reinforcement were associated with a greater hazard for autograft reoperation. Major internal or external bleeding occurred in 17 (0.15%/patient-year), and a total of 38 patients had composite end point of thrombosis, embolism, or bleeding (0.35%/patient-year). Late endocarditis with medical (n=16) or surgical treatment (n=29) was observed in 38 patients (0.38%/patient-year). Freedom from any valve-related event was 94.9% at 1 year, 90.7% at 5 years, and 82.5% at 10 years.

CONCLUSIONS

Although longer follow-up of patients who undergo Ross operation is needed, the present series confirms that the autograft procedure is a valid option to treat aortic valve disease in selected patients. The nonreinforced full root technique and preoperative aortic regurgitation are predictors for autograft failure and warrant further consideration. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00708409.

Minimally Invasive Options for Failing Homografts in the Pulmonary Position

Homograft implantation in the pulmonary position is usually part of initial repair in congenital heart defects with dysplasia or atresia of the pulmonary valve and at the time of the Ross operation. As part of reoperations, homografts are mainly required after nonvalved right ventricular outflow tract procedures. Due to an annual increase of homograft dysfunction, replacement is inevitable. Recently, percutaneous catheter-based valve implantations gain increasing acceptance. Even transventricular pulmonary valve implantation has been reported. Prior to decision making for any surgical or interventional therapy, the right ventricular outflow tract morphology together with additional pathologies need to be assessed. With the development of new prostheses and delivery modes, the demand for conventional surgery will further decrease.

Controlled delivery of heat shock protein using an injectable microsphere/hydrogel combination system for the treatment of myocardial infarction

Myocardial infarction causes a high rate of morbidity and mortality worldwide, and heat shock proteins as molecular chaperones have been attractive targets for protecting cardiomyoblasts under environmental stimuli. In this study, in order to enhance the penetration of heat shock protein 27 (HSP27) across cell membranes, we fused HSP27 with transcriptional activator (TAT) derived from human immunodeficiency virus (HIV) as a protein transduction domain (PTD). We loaded the fusion protein (TAT-HSP27) into microsphere/hydrogel combination delivery systems to control the release behavior for prolonged time periods. We found that the release behavior of TAT-HSP27 was able to be controlled by varying the ratio of PLGA microspheres and alginate hydrogels. Indeed, the released fusion protein maintained its bioactivity and could recover the proliferation of cardiomyoblasts cultured under hypoxic conditions. This approach to controlling the release behavior of TAT-HSP27 using microsphere/hydrogel combination delivery systems may be useful for treating myocardial infarction in a minimally invasive manner.

Follow-up of Shelhigh porcine pulmonic valve conduits

BACKGROUND

We implanted Shelhigh porcine pulmonic valve conduits because of the limited availability of homografts in our country. The aim of this study was to evaluate the short-term results of SPVC.

METHODS

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

RESULTS

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

CONCLUSIONS

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