Complete Aortic Valve Cusp Replacement in the Pediatric Population Using Tissue-Engineered Bovine Pericardium

Bicuspid Aortic Valve in Children and Young Adults for Cardiologists and Cardiac Surgeons: State-of-the-Art of Literature Review

Bicuspid aortic valve disease is the most prevalent congenital heart disease, affecting up to 2% of the general population. The presentation of symptoms may vary based on the patient's anatomy of fusion, with transthoracic echocardiography being the primary diagnostic tool. Bicuspid aortic valves may also appear with concomitant aortopathy, featuring fundamental structural changes which can lead to valve dysfunction and/or aortic dilatation over time. This article seeks to give a comprehensive overview of the presentation, treatment possibilities and long-term effects of this condition. The databases MEDLINE, Embase, and the Cochrane Library were searched using the terms "endocarditis" or "bicuspid aortic valve" in combination with "epidemiology", "pathogenesis", "manifestations", "imaging", "treatment", or "surgery" to retrieve relevant articles. We have identified two types of bicuspid aortic valve disease: aortic stenosis and aortic regurgitation. Valve replacement or repair is often necessary. Patients need to be informed about the benefits and drawbacks of different valve substitutes, particularly with regard to life-long anticoagulation and female patients of childbearing age. Depending on the expertise of the surgeon and institution, the Ross procedure may be a viable alternative. Management of these patients should take into account the likelihood of somatic growth, risk of re-intervention, and anticoagulation risks that are specific to the patient, alongside the expertise of the surgeon or centre. Further research is required on the secondary prevention of patients with bicuspid aortic valve (BAV), such as lifestyle advice and antibiotics to prevent infections, as the guidelines are unclear and lack strong evidence.

Characterization of a decellularized pericardium extracellular matrix hydrogel for regenerative medicine: insights on animal-to-animal variability

In the past years, the use of hydrogels derived from decellularized extracellular matrix (dECM) for regenerative medicine purposes has significantly increased. The intrinsic bioactive and immunomodulatory properties indicate these materials as promising candidates for therapeutical applications. However, to date, limitations such as animal-to-animal variability still hinder the clinical translation. Moreover, the choice of tissue source, decellularization and solubilization protocols leads to differences in dECM-derived hydrogels. In this context, detailed characterization of chemical, physical and biological properties of the hydrogels should be performed, with attention to how these properties can be affected by animal-to-animal variability. Herein, we report a detailed characterization of a hydrogel derived from the decellularized extracellular matrix of bovine pericardium (dBP). Protein content, rheological properties, injectability, surface microstructure, in vitro stability and cytocompatibility were evaluated, with particular attention to animal-to-animal variability. The gelation process showed to be thermoresponsive and the obtained dBP hydrogels are injectable, porous, stable up to 2 weeks in aqueous media, rapidly degrading in enzymatic environment and cytocompatible, able to maintain cell viability in human mesenchymal stromal cells. Results from proteomic analysis proved that dBP hydrogels are highly rich in composition, preserving bioactive proteoglycans and glycoproteins in addition to structural proteins such as collagen. With respect to the chemical composition, animal-to-animal variability was shown, but the biological properties were not affected, which remained consistent in different batches. Taken together these results show that dBP hydrogels are excellent candidates for regenerative medicine applications.

Lifetime Management of Adolescents and Young Adults with Congenital Aortic Valve Disease

In this invited expert review, we focus on evolving lifetime management strategies for adolescents and young adults with congenital aortic valve disease, acknowledging that these patients often require multiple interventions during their lifetime. Our goal is to preserve the native aortic valve when feasible. Leveraging advanced multimodality imaging, a detailed assessment of the aortic valve and root complex can be obtained, and a surgically approach tailored to an individual patient's anatomy and pathology can be used. In turn, aortic valve repair and reconstruction can be offered to a greater number of patients, either as a definitive strategy or as a component of a staged strategy to delay the need for aortic valve replacement until later in life when more options are available.

Aortic valve repair in the pediatric population: emerging role of aortic valve neocuspidization (AVNeo procedure)

Management of aortic valve diseases in children is challenging owing to the quality and quantity of the native tissue for repair, limitations in the currently available biological materials to supplement the repair and to achieve a long-lasting durable repair in an annulus where there is still growth potential. The aortic valve neocuspidization (AVNeo) procedure has emerged as a versatile alternative strategy in the armamentarium of pediatric aortic valve reconstructions that are currently available. In this review article, the focus of the discussion will be on the various aortic valve repair procedures in the pediatric population, with a special emphasis on the emerging role of AVNeo procedure in pediatrics and its outcomes.

Calcification Causing Failure of Tissue Engineered Bovine Pericardium After Aortic Valve Repair

CardioCel^® is bovine pericardium which is subjected to a novel tissue engineering process (ADAPT^®) to reduce cytotoxicity and retard calcification while maintaining strength and elasticity. We present a case where CardioCel^® showed rapid degeneration and calcification after repair of an aortic valve.

Single-Leaflet Aortic Valve Reconstruction Utilizing the Ozaki Technique in Patients With Congenital Aortic Valve Disease

Evaluate outcomes of single leaflet aortic valve reconstruction using Ozaki sizer and template. Single institute retrospective analysis between August 2015 and August 2019. Thirty-three patients, median age 9.3 years and weight 29.2 kg underwent single leaflet Ozaki repair. Preoperative indications were: AR (n = 17), AS (n = 3) or AS/AR (n = 13). Baseline anatomy was unicuspid (n = 15), bicuspid (n = 9) or tricuspid (n = 9). Two patients had endocarditis. Prior interventions included balloon valvuloplasty (n = 22) and aortic valve repair (n = 9). Pre-op average native annulus diameter was 19.6 mm and peak echo gradient was 36 mm Hg. Autologous pericardium, Photofix and CardioCel bovine pericardium were used in 26, 5, and 2 patients. Non-coronary sinus enlargement was required in 3 and aortic root reduction in 9 patients. Single leaflet reconstruction was done for the right coronary cusp (n = 25), non-coronary cusp in (n = 6) and left coronary cusp (n = 2). Additional procedures were done in 30 patients. Median ICU and hospital LOS were 2.1 and 6.3 days. There were no early re-interventions or conversions to valve replacement and one unrelated mortality.en At discharge, all patients had < moderate AR and/or AS with average peak gradients of 15 mm Hg. The median follow-up was 1.1 year, (IQR 0.7-1.8 years). Freedom from ≥ moderate AR and AS at 2 years was 76% and 86%. One patient required surgical re-intervention for severe AR 1.5 years after surgery for inflammatory infiltrate with calcification and fibrosis. Single-leaflet aortic valve leaflet reconstruction utilizing the Ozaki technique has promising early results and can be considered in patients when there are acceptable native leaflets.

Trileaflet Aortic Valve Reconstruction Using Bovine Pericardium

AIM

For several years now, trileaflet aortic valve reconstruction has been performed in patients with various aortic valve diseases. This study aimed to explore the feasibility and durability of trileaflet aortic valve reconstruction with bovine pericardium.

METHOD

Trileaflet aortic valve reconstruction with bovine pericardium was performed in 519 patients with various aortic valve diseases from April 2008 to December 2019. The results for all 519 patients were reviewed retrospectively. Mean age was 48.04±19.08 years (range, 13-80 years), and 40 patients were younger than 18 years of age. Thirty-four (34) patients had aortic stenosis, 344 patients had aortic regurgitation, and 141 patients had both aortic stenosis and regurgitation. One hundred and fifty-four (154) patients had bicuspid aortic valves, and three patients had quadricuspid aortic valves. The size of the pericardial leaflets was designed to be individually proportional to the size of the aortic root.

RESULTS

Mean length of follow-up was 41.97±22.68 years (range, 1-127 months). In total, 448 patients were reviewed, and the follow-up rate was 86.4%. All procedures were successful without conversion to prosthetic valve replacement during the procedure. Six (6) patients died after the procedure (in-hospital mortality, 1.2%). All-cause mortality occurred in 11 patients during the follow-up period. The 10-year cumulative survival rate was 94.7%±2.9%. Redo aortic valve surgery was performed in 11 patients after the procedure. The actuarial freedom from redo aortic valve surgery after the procedure was 88.2%±5.2%. At the end of the follow-up, the mean peak was 29.1±9.6 mmHg and mean gradient was 15.6±6.2 mmHg.

CONCLUSIONS

The mid- and long-term outcomes in patients with various aortic valve diseases undergoing trileaflet aortic valve reconstruction with bovine pericardium are encouraging. The engineered pericardial leaflets should be individually proportional to the size of the aortic root.

[Prosthetic repair of aortic valve cusps with autopericardium in children. State of the art and prospects]

According to the results of modern researchers, the main techniques used in congenital pathology of the aortic valve in children include balloon catheter dilatation of the aortic valve, surgical valvuloplasty, the Ross procedure and replacement of the aortic valve with a mechanical prosthesis. Many surgeons point out that these techniques in congenital pathology of the aortic valve yield suboptimal results. This is often due to the lack of a clear-cut definition between surgeons as to what operation should be performed in a particular age group. According to the reports of the majority of researchers, biological prostheses undergo early degeneration and structural changes in paediatric cardiac surgery and yield the worst results. Comparing the main techniques, optimal haemodynamics is observed after the Ross procedure. A disadvantage of this operation is the necessity of repeat intervention on the right ventricular outflow tract, which is required in 20 to 40%. Concomitant surgery of the mitral valve and/or aortic arch during the Ross procedure significantly increases the lethality and the risk of postoperative complications. Compared with an adult cohort of patients, children after prosthetic repair of the aortic valve using a mechanical prosthesis are more often found to have postoperative complications and a higher mortality rate. Yet another problem encountered in paediatric valve surgery is the unavailability of commercial prostheses sized ?19 mm. The duration of the intraoperative parameters for reconstructions of the aortic valve, the Ross procedure, and replacement of the aortic valve by the results of many studies averagely amounts to 74±34 min, 100±56 min, and 129±71 min, respectively. Yet another method which can be used for neocuspidization of the aortic valve in reconstructive surgery of the aortic root in paediatric patients is the use of glutaraldehyde-treated autologous pericardium. In our opinion, given the simplicity of the procedure, duration of the intraoperative parameters, and acceptable initial results reported by some researchers, the Ozaki procedure may be performed in children.

Unicuspid Aortic Valve Repair Using Geometric Ring Annuloplasty

BACKGROUND

Unicuspid aortic valves (Sievers type 2 bicuspid) are characterized by major fusion and clefting of the right-left coronary commissure, and minor fusion of the right-noncoronary commissure. Repair has been difficult because of two fusions, variable relative sinus sizes, and peripheral leaflet deficiencies or tears after balloon valvuloplasty.

METHODS

Twenty unicuspid aortic valves patients underwent valve repair in nine institutions. Right-left major fusion and right-noncoronary minor fusion occurred in 17 of 20 (85%). Commissurotomy was performed on the minor fusion, and a bicuspid annuloplasty ring with circular base geometry and two 180-degree subcommissural posts was sutured beneath the annulus, equalizing the annular circumferences of the fused and nonfused cusps. The nonfused leaflet was plicated, and the cleft in the major fusion was closed linearly until leaflet effective heights and lengths became greater than 8 mm and equal, respectively.

RESULTS

Average age (mean ± SD) was 22.3 ± 12.3 years (range, 13 to 58), 12 of 20 (60%) were symptomatic, 10 of 20 (50%) required aortic aneurysm resection. Pre-repair hemodynamic data included mean systolic valve gradient 25.8 ± 12.9 mm Hg, aortic insufficiency grade 2.9 ± 1.2, and annular diameter 24.7 ± 3.3 mm. No mortality or major complications occurred. Post-repair annular (ring) size was 20.5 ± 1.3 mm, mean gradient fell to 16.2 ± 5.9 mm Hg, and aortic insufficiency grade decreased to 0.1 ± 0.3 (P < .001). At an average follow-up of 11 months (range, 1 to 22), all 20 patients were asymptomatic and had returned to full activity.

CONCLUSIONS

Aortic ring annuloplasty reduced annular diameter effectively, recruiting more leaflet to midline coaptation. Minor fusion commissurotomy and annular remodeling to 180-degree commissures converted UAV repair to a simple and reproducible procedure.

Clinical history and management of bicuspid aortic valve in children and adolescents

Bicuspid aortic valve (BAV) is one of the most common congenital heart defects in children, adolescents and adults. BAV can occur as an isolated lesion or in association with other congenital heart defects, such as coarctation of the aorta or genetic syndromes like Turner syndrome. Although the majority of long term complications associated with BAV manifest later in life, children and adolescents may present with early onset valvular dysfunction or dilation of the aorta. BAV is a heterogeneous disease with a wide array of presentations at various ages, depending on the degree of aortic valve dysfunction, aortic dilation and presence of associated lesions. Aortic valve stenosis and/or regurgitation are the primary indications for intervention in children and adolescents with BAV. Although a majority of young patients with BAV also have some aortic dilation, interventions on the aorta are very rare during this time frame. Children and adolescents with BAV benefit from comprehensive assessment of their risk profile to determine follow-up surveillance intervals, sports recommendations, and timing of surgical intervention. The morphologic phenotype of BAV is important to identify, as it may predict future complications and prognosis.

Congenital aortic and truncal valve reconstruction using the Ozaki technique: Short-term clinical results

OBJECTIVES

Aortic valve reconstruction (AVRec) with neocuspidization or the Ozaki procedure with complete cusp replacement for aortic valve disease has excellent mid-term results in adults. Limited results of AVRec in pediatric patients have been reported. We report our early outcomes of the Ozaki procedure for congenital aortic and truncal valve disease.

METHODS

A retrospective analysis was performed on all 57 patients with congenital aortic and truncal valve disease who had a 3-leaflet Ozaki procedure at a single institution from August 2015 to February 2019. Outcome measures included mortality, surgical or catheter-based reinterventions, and echocardiographic measurements.

RESULTS

Twenty-four patients had aortic regurgitation (AR), 6 had aortic stenosis (AS), and 27 patients had AS/AR. Two patients had quadricuspid valves, 26 had tricuspid, 20 had bicuspid, and 9 had unicusp aortic valves. Four patients had truncus arteriosus. Thirty-four patients had previous aortic valve repairs and 5 had replacements. Preoperative echocardiography mean annular diameter was 20.90 ± 4.98 cm and peak gradient for patients with AS/AR was 53.62 ± 22.20 mm Hg. Autologous, Photofix, and CardioCel bovine pericardia were used in 20, 35, and 2 patients. Eight patients required aortic root enlargement and 20 had sinus enlargement. Fifty-one patients had concomitant procedures. Median intensive care unit and hospital length of stay were 1.87 and 6.38 days. There were no hospital mortalities or early conversions to valve replacement. At discharge, 98% of patients had mild or less regurgitation and peak aortic gradient was 16.9 ± 9.5 mm Hg. Two patients underwent aortic valve replacement. At median follow-up of 8.1 months, 96% and 91% of patients had less than moderate regurgitation and stenosis, respectively.

CONCLUSIONS

The AVRec procedure has acceptable short-term results and should be considered for valve reconstruction in pediatric patients with congenital aortic and truncal valve disease. Longer-term follow-up is necessary to determine the optimal patch material and late valve function and continued annular growth.

Performance of the ADAPT-Treated CardioCel® Scaffold in Pediatric Patients With Congenital Cardiac Anomalies: Medium to Long-Term Outcomes

Background: A Phase II Clinical Trial reviewed the performance (morbidity and calcification) of the tissue-engineered ADAPT® bovine pericardial scaffold (CardioCel®) in pediatric patients (n = 30) with congenital cardiac defects. In that study, CardioCel® demonstrated no graft-related morbidity and mortality in 25 patients, over 12 months. Five patients died due to non-graft-related events. Echocardiography revealed hemodynamically stable repairs with no calcification of the scaffold. Magnetic resonance imaging (MRI) at 12 months in 10 patients confirmed the absence of calcification. These patients were followed up for further up to 10 years. We present the results of this retrospective review of these patients that were followed for further medium to long-term (median 7.2 years, 25%: 3.6 years 75%: 9.25 years) postoperatively in these patients. Methods: Between April 2008 and September 2009, CardioCel® was implanted in 30 patients with congenital cardiac defects. Efficacy measures included graft-related mortality, morbidity and haemodynamic abnormalities. Calcification was assessed by standard 2D-M mode echocardiography and MRI at 12 months. Medium to long-term assessment included routine clinical assessments and echocardiography. Results: Median age at surgery was 18 months (27 days-13 years). Twenty-five patients (142 patient years) were followed for up to 10 years. The 10-year survival rate is estimated as 86.9% (95% CI 71.4-100.0%) over the entire follow-up period. One patient was lost to follow-up. No graft-related mortality was encountered up to a median follow-up of 7.2 years. Two patients died (pacemaker complications >5 years and arrhythmia >7 years postoperatively). No graft failure, thromboembolic events, infections or device-related reinterventions were recorded. Non-significant residual leaks occurred in 3 patients. Echocardiography demonstrated the absence of calcification in all implants. Conclusion: The tissue-engineered ADAPT® bovine pericardial scaffold demonstrated excellent medium to long-term performance (up to 10 years) when used as a scaffold for repair of congenital cardiac defects in children. Durability, acellularity, biostability and non-calcifying potential of CardioCel® makes it a very attractive tissue for congenital cardiac repair procedures.

Aortic valve neo-cuspidation using the Ozaki technique for acquired and congenital disease: where does this procedure currently stand?

The surgical treatment options for pediatric aortic valve disease are limited. The Ozaki procedure, which involves templated creation of new aortic valve leaflets, has proved to be a promising surgical technique. This review aims at elaborating the indications, technical intricacies, and outcomes of the aortic valve neo-cuspidization procedure (Ozaki procedure) in the pediatric population.

The Ozaki Procedure With CardioCel Patch for Children and Young Adults With Aortic Valve Disease: Preliminary Experience – a Word of Caution

Background:

The Ozaki procedure is a surgical technique for patients with significant aortic stenosis or regurgitation or both where valve repair cannot be performed. Individual cusps are cut from glutaraldehyde-treated autologous pericardium or bovine pericardium and implanted into the aortic valve position. Encouraging results have been reported within the adult population. There are limited published data on success of this procedure in younger patients.

Methods:

We present a series of five children and young adults who underwent the Ozaki procedure with neoaortic valve cusps made from CardioCel, a decellularized bovine pericardial patch treated with a monomeric glutaraldehyde.

Results:

There were no complications in the initial postoperative period and short inpatient stay. At a mean follow-up of 29.6 months (range: 22-36 months), 4 patients had no evidence of stenosis and 3 patients had trivial or no regurgitation from the neoaortic valve. Overall, two patients had complications related to the valve and underwent reintervention during the follow-up period with a Ross procedure. One of these patients who was not taking long-term anticoagulation experienced a transient ischemic attack.

Conclusions:

Our experience demonstrates that the Ozaki procedure with CardioCel in pediatric and young adult patients should be approached with caution. Further research with larger groups of pediatric patients, comparison of different graft materials, and longer follow-up is required to ascertain long-term success in children.

Aortic valve construction using pericardial tissue: short-term single-centre outcomes

OBJECTIVES

Aortic valve construction using pericardial tissue has been known since the late 1960s. The procedure was re-introduced by Ozaki in 2010 and is currently used to treat specific aortic valve diseases. The exact sizing of the neo-cusps and the insertion of the commissures remain the keys to success when performing this procedure. We evaluated our experience using modified custom-made templates.

METHODS

In this prospective single-centre study, we evaluated 52 consecutive patients who underwent aortic valve construction between September 2015 and March 2017 using either autologous (16 patients, 30.8%) or tissue-engineered pericardium (36 patients, 69.2%). Most patients (34, 65.4%) presented with aortic stenosis or endocarditis (5, 9.6%). Twenty patients had bicuspid and 5 had unicuspid valves. A modified sizing technique with specially designed templates was used. The primary end point was early death; the secondary end points were major adverse cardiac and cerebrovascular events, freedom from reoperation and overall mortality rate. Echocardiographic follow-up was performed intraoperatively and at 12-month intervals.

RESULTS

The mean age was 60 ± 14 years; 63.5% were men; and 34 (65.4%) patients had combined procedures. The mean cross-clamp time was 99 ± 17 min. Early outcomes included 1 stroke, 2 patients needing short-term dialysis and 1 death. During follow-up (mean 11.2 ± 4.8 months), trace aortic regurgitation was observed in 4 patients; the mean pressure gradient was 6.8 ± 2.9 mmHg. Three patients died later (of non-cardiac reasons), and 5 patients needed reoperation due to endocarditis.

CONCLUSIONS

Aortic valve construction using pericardial tissue could be an alternative in middle-age patients presenting with aortic valve disease in whom valve repair was not possible. The newly designed templates allow exact sizing of the neo-cusps and optimal commissure implantation; however, long-term follow-up in a larger cohort is warranted to assess the durability of the neo-valves.

The great debate series: surgical treatment of aortic valve abnormalities in children

This article is the latest in an EJCTS series entitled 'The Great Debates'. We have chosen the topic of aortic valve (AoV) surgery in children, with a focus on infants and neonates. The topic was selected due to the significant challenges that AoV problems in the young may present to the surgical team. There are many areas of active controversy, despite the vast accumulated world experience. We have tried to incorporate many of these issues in the questions posed, not claiming to be all-inclusive. The individuals invited to this debate are experts in paediatric valve surgery, with broad and successful clinical experiences on multiple continents. We hope that the facts and opinions presented in this debate will generate interest and discussion and perhaps prove useful in decision-making for future complex valve cases.

Biodegradable and biomimetic elastomeric scaffolds for tissue-engineered heart valves

Valvular heart diseases are the third leading cause of cardiovascular disease, resulting in more than 25,000 deaths annually in the United States. Heart valve tissue engineering (HVTE) has emerged as a putative treatment strategy such that the designed construct would ideally withstand native dynamic mechanical environment, guide regeneration of the diseased tissue and more importantly, have the ability to grow with the patient. These desired functions could be achieved by biomimetic design of tissue-engineered constructs that recapitulate in vivo heart valve microenvironment with biomimetic architecture, optimal mechanical properties and possess suitable biodegradability and biocompatibility. Synthetic biodegradable elastomers have gained interest in HVTE due to their excellent mechanical compliance, controllable chemical structure and tunable degradability. This review focuses on the state-of-art strategies to engineer biomimetic elastomeric scaffolds for HVTE. We first discuss the various types of biodegradable synthetic elastomers and their key properties. We then highlight tissue engineering approaches to recreate some of the features in the heart valve microenvironment such as anisotropic and hierarchical tri-layered architecture, mechanical anisotropy and biocompatibility.

STATEMENT OF SIGNIFICANCE

Heart valve tissue engineering (HVTE) is of special significance to overcome the drawbacks of current valve replacements. Although biodegradable synthetic elastomers have emerged as promising materials for HVTE, a mature HVTE construct made from synthetic elastomers for clinical use remains to be developed. Hence, this review summarized various types of biodegradable synthetic elastomers and their key properties. The major focus that distinguishes this review from the current literature is the thorough discussion on the key features of native valve microenvironments and various up-and-coming approaches to engineer synthetic elastomers to recreate these features such as anisotropic tri-layered architecture, mechanical anisotropy, biodegradability and biocompatibility. This review is envisioned to inspire and instruct the design of functional HVTE constructs and facilitate their clinical translation.

Application of the CardioCel bovine pericardial patch - a preliminary report

Introduction

Animal pericardial patches are widely used in adult and pediatric cardiac surgery. A search is ongoing for a new material with optimal surgical properties that will reduce intraoperative bleeding and the occurrence of restenosis, calcification, and pseudoaneurysms in long-term observation. One product of interest is the CardioCel bovine pericardial patch.

Aim

Evaluation of the short-term results of CardioCel bovine pericardial patch implantation during pediatric cardiac surgery.

Material and methods

The study included 8 patients who underwent surgical correction of congenital cardiac defects between January 2015 and February 2016. Pericardial patches were used to repair supravalvular aortic stenosis and reconstruct the aortic arch and pulmonary arteries. The age of the patients ranged from 10 days to 14 years.

Results

There were no hospital deaths. The new material exhibited satisfactory durability and elasticity during surgery, facilitating optimal adaptation of the patch to the patient's tissues. No significant bleeding was reported from the suture site. The median duration of follow-up was 58 days. During the follow-up, there were no symptoms of pseudoaneurysm formation, patch thickening, or calcification in the areas where the pericardial patches were implanted. No clinical or laboratory symptoms of infection were observed in locations where the new material was applied.

Conclusions

Satisfactory surgical properties of the patch were observed intraoperatively. Positive results using the new pericardial patch were obtained in short-term follow-up.