Pulmonary valve replacement after right ventricular outflow tract reconstruction with homograft vs Contegra®: a case control comparison of mortality and morbidity

One-Year Outcome of an Ongoing Pre-Clinical Growing Animal Model for a Tissue-Engineered Valved Pulmonary Conduit

Objectives: A self-constructed valved pulmonary conduit made out of a de-cellularized porcine small intestinal submucosal extracellular matrix biological scaffold was tested in a chronic growing lamb model. Methods: The conduit was implanted in pulmonary valve position in 19 lambs. We monitored clinical, laboratory, and echocardiographic findings until 12 months after surgery. In two animals, euthanasia was planned at nine and twelve months. Pre-mortem chest computed tomography and post-mortem pathologic work up were performed. Data are presented as frequency and percentage, median and range, or mean and standard deviation. Results: Twelve (63.2%) animals survived the perioperative period. Three unexpected deaths occurred during the follow-up period: one due to aspiration pneumonia at 23 days after surgery, and two due to early and late infective endocarditis of the conduit at 18 and 256 days. In the two animals with planned scarification, the pre-mortem CT scan revealed mild or no calcification within the conduit or valve leaflets. In the echocardiographic examination at 12 months, peak and mean systolic pressure gradients across the conduit valve were 6.5 (3-21) mmHg and 3 (2-12) mmHg, while valve regurgitation was none (n = 2), trivial (n = 5), moderate (n = 1), or severe (n = 1). No clinical or laboratory signs of hemolysis were seen. After 12 months of follow-up, the animals' body weights had increased from 33 (27-38) kg to 53 (38-66) kg (p = 0.010). Conclusions: Implantation of a valved pulmonary conduit in our growing lamb model was feasible. Infective endocarditis of the implanted valved conduit remained a significant complication.

Matched comparison of decellularized homografts and bovine jugular vein conduits for pulmonary valve replacement in congenital heart disease

For decades, bovine jugular vein conduits (BJV) and classic cryopreserved homografts have been the two most widely used options for pulmonary valve replacement (PVR) in congenital heart disease. More recently, decellularized pulmonary homografts (DPH) have provided an alternative avenue for PVR. Matched comparison of patients who received DPH for PVR with patients who received bovine jugular vein conduits (BJV) considering patient age group, type of heart defect, and previous procedures. 319 DPH patients were matched to 319 BJV patients; the mean age of BJV patients was 15.3 (SD 9.5) years versus 19.1 (12.4) years in DPH patients (p = 0.001). The mean conduit diameter was 24.5 (3.5) mm for DPH and 20.3 (2.5) mm for BJV (p < 0.001). There was no difference in survival rates between the two groups after 10 years (97.0 vs. 98.1%, p = 0.45). The rate of freedom from endocarditis was significantly lower for BJV patients (87.1 vs. 96.5%, p = 0.006). Freedom from explantation was significantly lower for BJV at 10 years (81.7 vs. 95.5%, p = 0.001) as well as freedom from any significant degeneration at 10 years (39.6 vs. 65.4%, p < 0.001). 140 Patients, matched for age, heart defect type, prior procedures, and conduit sizes of 20-22 mm (± 2 mm), were compared separately; mean age BJV 8.7 (4.9) and DPH 9.5 (7.3) years (p = n.s.). DPH showed 20% higher freedom from explantation and degeneration in this subgroup (p = 0.232). Decellularized pulmonary homografts exhibit superior 10-year results to bovine jugular vein conduits in PVR.

Right ventricle to pulmonary artery conduit: a comparison of long-term graft-related events between bovine jugular vein conduit, aortic homograft, and porcine-valved conduits

Background

The optimal conduit for right ventricle to pulmonary artery (RV-PA) reconstruction does not exist. Reinterventions are common due to conduit stenosis and endocarditis. Tailoring conduit choice according to patients' characteristics could improve the outcomes. The study aimed to compare graft-related events (infective endocarditis, transcatheter pulmonary valve replacement (PVR), transcatheter conduit dilatation, surgical conduit replacement, and transcatheter pulmonary branch intervention for RV-PA reconstruction using bovine jugular vein, aortic homograft, and porcine-valved conduits.

Methods

In a retrospective cohort study, 155 patients with 193 procedures that were done in King Faisal Specialist Hospital and Research Center-Jeddah (KFSHRC JED) for implanting RV-PA conduits from 1999 to 2021 were included. The patients were grouped according to the type of conduit into 3 groups; Group 1 (n=153) received bovine jugular vein (BJVs) grafts, Group 2 (n=29) received aortic homografts, Group 3 (n=11) received porcine-valved conduits. Factors associated with graft-related events were evaluated using stepwise Cox regression analysis.

Results

Patients with BJVs were significantly younger than those with porcine-valved conduits 3 (P=0.009). The weight of BJVs patients was significantly lower than homografts (P=0.002) and porcine-valved conduits patients 3 (P<0.001). The conduit size was as expected significantly lower in BJVs patients than patients who received porcine-valved conduits (P<0.001) and patients who received aortic homografts (P<0.001). There was no difference between Group 2 and 3 (P=0.084). Operative mortality occurred in 13 patients: 12 (7.84%) with BJV conduit and 1 (9.09%) with porcine valved conduit (P=0.351). Male gender [odds ratio (OR): 10.04; 95% confidence interval (CI): 1.28-78.86; P=0.028] and smaller conduit size (OR: 0.78; 95% CI: 0.61-0.99; P=0.048) were associated with increased operative mortality. Freedom from graft-related events at 5 and 10 years was 67% and 52% in BJVs patients, 74% and 36% in patients who received aortic homografts, and 53% in patients who received porcine-valved conduits. Factors associated with increased graft-related events were male gender (HR: 1.58; 95% CI: 1.004-2.50, P=0.048) and younger age (HR: 0.995; 95% CI: 0.991-0.999, P=0.041).

Conclusions

RV-PA reconstruction was associated with low mortality, unrelated to the conduit type. Reinterventions for graft-related events were common. The durability and graft-related events might be comparable among BJV grafts, aortic homografts, and porcine-valved conduits. Factors associated with increased graft-related events in this study were male gender and younger age.

Graft rejection in paediatric congenital heart disease

Congenital heart disease (CHD) affects around 1.35 million neonates worldwide per annum, and surgical repair is necessary in approximately 25% of cases. Xenografts, usually of bovine or porcine origin, are often used for the surgical reconstruction. These xenografts elicit an immune response due to significant immunological incompatibilities between host and donor. Current techniques to dampen the initial hyperacute rejection response involve aldehyde fixation to crosslink xenoantigens, such as galactose-α1,3-galactose and N-glycolylneuraminic acid. While this temporarily masks the epitopes, aldehyde fixation is a suboptimal solution, degrading over time, resulting in cytotoxicity and rejection. The immune response to foreign tissue eventually leads to chronic inflammation and subsequent graft failure, necessitating reintervention to replace the defective bioprosthetic. Decellularisation to remove immunoincompatible material has been suggested as an alternative to fixation and may prove a superior solution. However, incomplete decellularisation poses a significant challenge, causing a substantial immune rejection response and subsequent graft rejection. This review discusses commercially available grafts used in surgical paediatric CHD intervention, looking specifically at bovine jugular vein conduits as a substitute to cryopreserved homografts, as well as decellularised alternatives to the aldehyde-fixed graft. Mechanisms of biological prosthesis rejection are explored, including the signalling cascades of the innate and adaptive immune response. Lastly, emerging strategies of intervention are examined, including the use of tissue from genetically modified pigs, enhanced crosslinking and decellularisation techniques, and augmentation of grafts through in vitro recellularisation or functionalisation with human surface proteins.

Bovine jugular vein conduit replacement after homograft degeneration in patients with tetralogy of Fallot: The results of re-redo cases

Background

This study aims to present our experience and results in terms of reconstruction with bovine jugular vein conduit in re-redo patients who developed severe homograft degeneration with pulmonary homograft valve replacement.

Methods

Between May 2018 and May 2021, a total of 10 re-redo patients (4 males, 6 females; mean age: 16.5±3.0 years; range, 12 to 21 years) who underwent bovine jugular vein conduit replacement due to homograft degeneration were retrospectively analyzed. The clinical, pre-, intra-, and postoperative data of the patients were recorded.

Results

The mean age of the second operation (homograft replacement) was 8.5±3.8 (range, 4 to 14) years in the patients who underwent homograft replacement. No postoperative mortality was observed. When the pre- and postoperative findings were compared, the right ventricular outflow tract gradient, the degree of pulmonary and tricuspid regurgitation, and right ventricular dilatation were regressed (p<0.05). A significant improvement in the New York Heart Association functional class was observed in all patients after surgery.

Conclusion

After tetralogy of Fallot corrective surgery, repetitive surgical interventions are inevitable due to pulmonary valve deterioration. Therefore, a bovine jugular vein conduit may be a good alternative for conduit preference after pulmonary homograft failure in re-redo cases.

Cryopreserved human heart valve allografts: a ten-year single centre experience

This study provides an overview of tissue banking activities at the Croatian Cardiovascular Tissue Bank (CTB) during past ten years and presents the outcomes of cryopreserved heart valve allografts (CHAs) use in different patient groups. From June 2011 until December 2021, 75 heart donations were referred to CTB: 41 recipient of heart transplant (RHT), 32 donors after brain death (DBD) and 2 donors after circulatory death (DCD) donations. Processing resulted in 103 valves of which 65 met quality requirements for clinical use. Overall tissue discard rate was 37%. The most frequent reasons for discard were inadequate morphology (12%) in RHT donations and microbiological contamination (19%) in DBD donations. Altogether, 38 CHAs were transplanted to 36 patients. Recipients were divided in three groups; infective endocarditis (IE), non-infectious heart disease and congenital heart disease group. In the IE group, the 30-day, 1-year and 3-year survival was 71%, 53% and 47%, respectively. Freedom from re-operation due to all graft-related causes was 76% and due to structural valve deterioration 88%. There were no cases of graft reinfection. In the congenital heart disease group CHAs were predominantly (94%) used for right ventricular outflow tract reconstruction and 88% of patients recovered without graft-related complications. At present, the number of demands for CHAs at CTB considerably outweighs their availability.

Outcomes Following Heterotopic Placement of Right Ventricle to Pulmonary Artery Conduits

BACKGROUND

We sought to evaluate the outcomes following right ventricle to pulmonary artery (RV-PA) conduit placement in pediatric patients, excluding those with a RV-PA conduit for the Ross procedure which is associated with improved conduit durability, partly related to its orthotopic position.

METHODS

Outcomes for 119 patients who underwent RV-PA conduit placement at a single institution from January 2004 to December 2016 were reviewed. Primary outcome measures were reintervention-free survival (RFS) and overall survival. Survival analyses were performed using the Kaplan-Meier method, and risk factors associated with reintervention were evaluated.

RESULTS

The median age at the time of conduit placement was 6 months (interquartile range, IQR: 1-14), and the median length of follow-up was 63 months (range: 0-156). During follow-up, 39 patients required conduit-related reintervention, while 6 patients died perioperatively with an overall survival of 90% at 10 years. Among the remaining 113 patients, the RFS at one, five, and ten years was 91% (84%-95%), 72% (60%-80%), and 33% (16%-50%), respectively. The median time to conduit replacement in the series was 43.5 months (IQR: 19.3-76.2). The use of a pulmonary homograft was associated with improved RFS (P = .03), and this was particularly pronounced in comparison with aortic homografts in neonates. Infection was the indication for replacement in only one patient.

CONCLUSIONS

The majority of the conduits placed during the neonatal period required conduit replacement before the age of five years. Endocarditis was not a common indication for replacement. In neonates and infants, we prefer pulmonary homografts for most indications.

Midterm results of homografts in pulmonary position: a retrospective single-center study

Objective

Valved conduits play a pivotal role in the right ventricular outflow tract (RVOT) reconstruction in patients with congenital heart disease (CHD), and valved homografts have become the most commonly used conduits in pediatric cardiac surgery. This study aimed to assess the midterm performance of aortic and pulmonary homografts used in pulmonary position in patients with CHD.

Methods

Ninety-eight patients underwent surgical RVOT reconstruction with a homograft from January 2012 to December 2017. We collected all patient details from the institute patient record system. Echocardiographic data were obtained from the records. Postoperative data included survival and follow-up echocardiography. The primary endpoints of the study were homograft failure, homograft dysfunction, and freedom from re-intervention.

Results

We observed allograft failure in two patients (2%), one each due to pseudo-aneurysm formation and infective endocarditis. There were 8 early deaths (8/98, 8.2%) and 9 late deaths (9/98, 9.2%). The mean survival time was 6.1 years, and the postoperative survival rate at 1 and 5 years was 89.73% and 82.65%, respectively. Homograft regurgitation and homograft dysfunction were higher in the pulmonary homograft group. However, the re-intervention rates were more in the aortic homograft (24.24%) group due to the higher incidence of calcification associated with them.

Conclusion

Homografts used for RVOT reconstruction provide excellent intermediate-term outcomes, irrespective of the type of homograft used. Pulmonary homografts are more durable than aortic homografts and provide satisfactory results even in infants.

Establishing a pre-clinical growing animal model to test a tissue engineered valved pulmonary conduit

Background

Many valvular pathologies of the heart may be only sufficiently treated by replacement of the valve if a reconstruction is not feasible. However, structural deterioration, thrombosis with thromboembolic events and infective endocarditis are commonly encountered complications over time and often demand a re-operation. In congenital heart disease the lack of small diameter valves with the potential to grow poses additional challenges and limits treatment options to homo- or xenograft implants.

Methods

In this study, a chronic sheep model (24 months follow-up), a self-constructed valved conduit was created out of a tissue engineered (TE) patch (CorMatrix® Cardiovascular, Inc, USA) and implanted in orthotopic right ventricular (RV)-pulmonary artery (PA) position. Thereafter, the sheep were regularly monitored by clinical, laboratory and echocardiographic examinations to evaluate cardiac function and the implanted RV-PA-conduit.

Discussion

Here, we summarize the study protocol and our experiences during the perioperative phase and the follow up period and explain how we constructed a valved conduit out of a commercially available TE patch.

Trial registration

License number: ZH 284/14.

Pulmonary Valve Regurgitation: Neither Interventional Nor Surgery Fits All

Introduction: PV implantation is indicated for severe PV regurgitation after surgery for congenital heart defects, but debates accompany the following issues: timing of PV implantation; choice of the approach, percutaneous interventional vs. surgical PV implantation, and choice of the most suitable valve. Timing of pulmonary valve implantation: The presence of symptoms is class I evidence indication for PV implantation. In asymptomatic patients indication is agreed for any of the following criteria: PV regurgitation > 20%, indexed end-diastolic right ventricular volume > 120-150 ml/m2 BSA, and indexed end-systolic right ventricular volume > 80-90 ml/m2 BSA. Choice of the approach: percutaneous interventional vs. surgical: The choice of the approach depends upon the morphology and the size of the right ventricular outflow tract, the morphology and the size of the pulmonary arteries, the presence of residual intra-cardiac defects and the presence of extremely dilated right ventricle. Choice of the most suitable valve for surgical implantation: Biological valves are first choice in most of the reported studies. A relatively large size of the biological prosthesis presents the advantage of avoiding a right ventricular outflow tract obstruction, and also of allowing for future percutaneous valve-in-valve implantation. Alternatively, biological valved conduits can be implanted between the right ventricle and pulmonary artery, particularly when a reconstruction of the main pulmonary artery and/or its branches is required. Hybrid options: combination of interventional and surgical: Many progresses extended the implantation of a PV with combined hybrid interventional and surgical approaches. Major efforts have been made to overcome the current limits of percutaneous PV implantation, namely the excessive size of a dilated right ventricular outflow tract and the absence of a cylindrical geometry of the right ventricular outflow tract as a suitable landing for a percutaneous PV implantation. Conclusion: Despite tremendous progress obtained with modern technologies, and the endless fantasy of researchers trying to explore new forms of treatment, it is too early to say that either the interventional or the surgical approach to implant a PV can fit all patients with good long-term results.

Pulmonary Regurgitation- Is the Future Percutaneous or Surgical?

For decades, surgical replacement of the pulmonary valve has been seen as the gold-standard technique. Until the advent of Medtronic's Melody valve, it was the only option. Whilst radical changes in surgical techniques have not been forthcoming, rapid and substantial developments in the techniques and available technology for percutaneous valves now cause us to ask if the gold-standard moniker now belongs in the cath lab. This manuscript explores the recent history and future of a revolution in this large area of congenital cardiac practice.