Evaluation of Explanted CorMatrix Intracardiac Patches in Children With Congenital Heart Disease

Altered Inflammatory State and Mitochondrial Function Identified by Transcriptomics in Paediatric Congenital Heart Patients Prior to Surgical Repair

Congenital heart disease (CHD) remains the most common birth defect, with surgical intervention required in complex cases. Right ventricle (RV) function is known to be a major predictor of sustained cardiac health in these patients; thus, by elucidating the divergent profiles between CHD and the control through tissue analysis, this study aims to identify new avenues of investigation into the mechanisms surrounding reduced RV function. Transcriptomic profiling, in-silico deconvolution and functional network analysis were conducted on RV biopsies, identifying an increase in the mitochondrial dysfunction genes RPPH1 and RMPR (padj = 4.67 × 10-132, 2.23 × 10-107), the cytotoxic T-cell markers CD8a, LAGE3 and CD49a (p = 0.0006, p < 0.0001, and p = 0.0118) and proinflammatory caspase-1 (p = 0.0055) in CHD. Gene-set enrichment identified mitochondrial dysfunctional pathways, predominately changes within oxidative phosphorylation processes. The negative regulation of mitochondrial functions and metabolism was identified in the network analysis, with dysregulation of the mitochondrial complex formation. A histological analysis confirmed an increase in cellular bodies in the CHD RV tissue and positive staining for both CD45 and CD8, which was absent in the control. The deconvolution of bulk RNAseq data suggests a reduction in CD4+ T cells (p = 0.0067) and an increase in CD8+ T cells (p = 0.0223). The network analysis identified positive regulation of the immune system and cytokine signalling clusters in the inflammation functional network, as there were lymphocyte activation and leukocyte differentiation. Utilising RV tissue from paediatric patients undergoing CHD cardiac surgery, this study identifies dysfunctional mitochondrial pathways and an increase in inflammatory T-cell presence prior to reparative surgery.

Grafts and Patches: Optimized but Not Optimal Materials for Congenital Heart Surgery

A variety of materials are available for the surgery of children with congenital heart defects. In addition to growth-related mismatch, degeneration of the material in particular frequently leads to reoperation. Therefore, the choice of conduits and patches should be made carefully. This article provides an overview of the most commonly implanted materials in pediatric cardiac surgery.Structural changes can be detected in all available materials. Depending on the age at implantation and the site of implantation, the extent and time course of material degeneration vary. Autologous material is still the gold standard in reconstructive surgery. Biological materials have largely replaced artificial materials in clinical use.The search for the ideal material continues. In pediatric cardiac surgery, there are only optimized but no optimal materials.

Biological Scaffolds for Congenital Heart Disease

Congenital heart disease (CHD) is the most predominant birth defect and can require several invasive surgeries throughout childhood. The absence of materials with growth and remodelling potential is a limitation of currently used prosthetics in cardiovascular surgery, as well as their susceptibility to calcification. The field of tissue engineering has emerged as a regenerative medicine approach aiming to develop durable scaffolds possessing the ability to grow and remodel upon implantation into the defective hearts of babies and children with CHD. Though tissue engineering has produced several synthetic scaffolds, most of them failed to be successfully translated in this life-endangering clinical scenario, and currently, biological scaffolds are the most extensively used. This review aims to thoroughly summarise the existing biological scaffolds for the treatment of paediatric CHD, categorised as homografts and xenografts, and present the preclinical and clinical studies. Fixation as well as techniques of decellularisation will be reported, highlighting the importance of these approaches for the successful implantation of biological scaffolds that avoid prosthetic rejection. Additionally, cardiac scaffolds for paediatric CHD can be implanted as acellular prostheses, or recellularised before implantation, and cellularisation techniques will be extensively discussed.

Epicardial transplantation of autologous atrial appendage micrografts: evaluation of safety and feasibility in pigs after coronary artery occlusion

Objectives. Several approaches devised for clinical utilization of cell-based therapies for heart failure often suffer from complex and lengthy preparation stages. Epicardial delivery of autologous atrial appendage micrografts (AAMs) with a clinically used extracellular matrix (ECM) patch provides a straightforward therapy alternative. We evaluated the operative feasibility and the effect of micrografts on the patch-induced epicardial foreign body inflammatory response in a porcine model of myocardial infarction. Design. Right atrial appendages were harvested and mechanically processed into AAMs. The left anterior descending coronary artery was ligated to generate acute infarction. Patches of ECM matrix with or without AAMs were transplanted epicardially onto the infarcted area. Four pigs received the ECM and four received the AAMs patch. Cardiac function was studied by echocardiography both preoperatively and at 3-week follow-up. The primary outcome measures were safety and feasibility of the therapy administration, and the secondary outcome was the inflammatory response to ECM. Results. Neither AAMs nor ECM patch-related complications were detected during the follow-up time. AAMs patch preparation was feasible according to time and safety. Inflammation was greatly reduced in AAMs when compared with ECM patches as measured by the amount of infiltrated inflammatory cells and area of inflammation. Immunohistochemistry demonstrated an increased CD3+ cell density in the AAMs patch infiltrate. Conclusions. Epicardial AAMs transplantation demonstrated safety and clinical feasibility. The use of micrografts significantly inhibited ECM-induced foreign body inflammatory reactivity. Transplantation of AAMs shows good clinical applicability as adjuvant therapy to cardiac surgery and can suppress acute inflammatory reactivity.

Outcomes of Repair of Congenital Aortic Valve Lesions Using Autologous Pericardium vs Porcine Intestinal Submucosa

BACKGROUND

Outcomes following congenital aortic valve (AoV) repair are plagued by progressive dysfunction of currently available leaflet substitute materials.

OBJECTIVES

We compared the long-term outcomes of congenital AoV repair using porcine intestinal submucosa vs autologous pericardium (AP).

METHODS

This was a single-center retrospective review of all patients who underwent congenital AoV repair with either porcine intestinal submucosa or AP from October 2009 to March 2013. The primary outcome was postdischarge (late) unplanned AoV reintervention. Secondary outcomes included number of late AoV reinterventions and a composite of at least moderate aortic regurgitation or stenosis at latest follow-up or before the first reintervention. Associations between leaflet repair material and outcomes were assessed using multivariable regression models, adjusting for prespecified patient-related and operative variables.

RESULTS

Of 26 porcine intestinal submucosa and 49 AP patients who met entry criteria, the median age was 11.0 years (IQR: 4.7-16.6 years). At a median follow-up of 8.5 years (IQR: 4.4-9.6 years), 17 (65.4%) porcine intestinal submucosa and 22 (44.9%) AP patients underwent at least 1 AoV reintervention. On multivariable analysis, porcine intestinal submucosa use was significantly associated with unplanned AoV reintervention (HR: 4.6; 95% CI: 2.2-9.8; P < 0.001), number of postdischarge AoV reinterventions (incidence rate ratio: 1.7; 95% CI: 1.0-2.9; P = 0.037), and at least moderate aortic regurgitation or stenosis at latest follow-up or before the first reintervention (OR: 5.0; 95% CI: 1.2-21.0; P = 0.027).

CONCLUSIONS

Aortic valvuloplasty with porcine intestinal submucosa is associated with earlier time to reintervention compared with autologous pericardium. The search for the ideal AoV leaflet repair material continues.

Wharton's Jelly-Mesenchymal Stem Cell-Engineered Conduit for Pulmonary Artery Reconstruction in Growing Piglets

Surgical treatment of congenital heart defects affecting the right ventricular outflow tract often requires complex reconstruction and multiple reoperations. With a randomized controlled trial, we compared a novel tissue-engineered small intestine submucosa-based graft for pulmonary artery reconstruction (seeded with mesenchymal stem cells derived from Wharton's Jelly) with conventional small intestine submucosa in growing piglets. Six months after implantation, seeded grafts showed integration with host tissues at cellular level and exhibited growth potential on transthoracic echocardiography and cardiovascular magnetic resonance. Our seeded graft is a promising biomaterial for pulmonary artery reconstruction in pediatric patients with right ventricular outflow tract abnormalities.

Prospects for prevention of adhesion process during cardiac surgical interventions

The article is devoted to the problem of prevention of adhesions in cardiac surgery. It was determined that the problem is urgent due to the increase in the number of heart surgeries. The formation of adhesions is a reaction of the body after surgery, which is a stage of healing and partly performs a protective function. Nevertheless, the presence of adhesions violates the mechanical properties of the heart, negatively affects central hemodynamics, complicates the surgeon’s task during repeated surgical interventions and increases the risk of repeated operations.It has been shown that at present, for the prevention of adhesions, researchers tend to use biodegradable barrier materials with biocompatibility and the ability to dissolve after performing the barrier function. The main anti-adhesion agents used in cardiac surgery are membranes and gels. The requirements for an “ideal” agent for the prevention of adhesion were determined: biocompatibility, no irritating effect, no effect on wound healing, suppression of the growth of connective tissue in the pericardium.Conclusions. Until now, none of the funds has all the necessary qualities to prevent adhesion in the pericardium. Therefore, the search for effective methods for the prevention of postoperative adhesions remains relevant for cardiac surgery.

Pediatric aortic valve repair: Any development in the material for cusp extension valvuloplasty?

BACKGROUND

Aortic cusp extension is a technique for aortic valve (AV) repairs in pediatric patients. The choice of the material used in this procedure may influence the time before reoperation is required. We aimed to assess postoperative and long-term outcomes of patients receiving either pericardial or synthetic repairs.

METHODS

We conducted a single-center, retrospective study of pediatric patients undergoing aortic cusp extension valvuloplasty (N = 38) with either autologous pericardium (n = 30) or CorMatrix (n = 8) between April 2009 and July 2016. Short- and long-term postoperative outcomes were compared between the two groups. Freedom from reoperation was compared using Kaplan-Meier analysis. Degree of aortic stenosis (AS) and aortic regurgitation (AR) were recorded at baseline, postoperatively, and at outpatient follow-up.

RESULTS

At 5 years after repair, freedom from reoperation was significantly lower in the CorMatrix group (12.5%) compared to the pericardium group (62.5%) (p = .01). For the entire cohort, there was a statistically significant decrease in the peak trans-valvar gradient between preoperative and postoperative assessments with no significant change at outpatient follow-up. In the pericardium group, 28 (93%) had moderate to severe AR at baseline which improved to 11 (37%) postoperatively and increased to 21 (70%) at time of follow-up. In the biomaterial group, eight (100%) had moderate to severe AR which improved to three (38%) postoperatively and increased to seven (88%) at time of follow-up.

CONCLUSION

In terms of durability, the traditional autologous pericardium may outperform the new CorMatrix for AV repairs using the cusp extension method.

Stem Cells and Their Cardiac Derivatives for Cardiac Tissue Engineering and Regenerative Medicine

Significance: Heart failure is among the leading causes of morbidity worldwide with a 5-year mortality rate of ∼50%. Therefore, major efforts are invested to reduce heart damage upon injury or maintain and at best restore heart function. Recent Advances: In clinical trials, acellular constructs succeeded in improving cardiac function by stabilizing the infarcted heart. In addition, strategies utilizing stem-cell-derived cardiomyocytes have been developed to improve heart function postmyocardial infarction in small and large animal models. These strategies range from injection of cell-laden hydrogels to unstructured hydrogel-based and complex biofabricated cardiac patches. Importantly, novel methods have been developed to promote differentiation of stem-cell-derived cardiomyocytes to prevascularized cardiac patches. Critical Issues: Despite substantial progress in vascularization strategies for heart-on-the-chip technologies, little advance has been made in generating vascularized cardiac patches with clinically relevant dimensions. In addition, proper electrical coupling between engineered and host tissue to prevent and/or eliminate arrhythmia remains an unresolved issue. Finally, despite advanced approaches to include hierarchical structures in cardiac tissues, engineered tissues do not generate forces in the range of native adult cardiac tissue. Future Directions: It involves utilizing novel materials and advancing biofabrication strategies to generate prevascularized three-dimensional multicellular constructs of clinical relevant size; inclusion of hierarchical structures, electroconductive materials, and biologically active factors to enhance cardiomyocyte differentiation for optimized force generation and vascularization; optimization of bioreactor strategies for tissue maturation. Antioxid. Redox Signal. 35, 143-162.

Polymeric Biomaterials for the Treatment of Cardiac Post-Infarction Injuries

Cardiac regeneration aims to reconstruct the heart contractile mass, preventing the organ from a progressive functional deterioration, by delivering pro-regenerative cells, drugs, or growth factors to the site of injury. In recent years, scientific research focused the attention on tissue engineering for the regeneration of cardiac infarct tissue, and biomaterials able to anatomically and physiologically adapt to the heart muscle have been proposed as valuable tools for this purpose, providing the cells with the stimuli necessary to initiate a complete regenerative process. An ideal biomaterial for cardiac tissue regeneration should have a positive influence on the biomechanical, biochemical, and biological properties of tissues and cells; perfectly reflect the morphology and functionality of the native myocardium; and be mechanically stable, with a suitable thickness. Among others, engineered hydrogels, three-dimensional polymeric systems made from synthetic and natural biomaterials, have attracted much interest for cardiac post-infarction therapy. In addition, biocompatible nanosystems, and polymeric nanoparticles in particular, have been explored in preclinical studies as drug delivery and tissue engineering platforms for the treatment of cardiovascular diseases. This review focused on the most employed natural and synthetic biomaterials in cardiac regeneration, paying particular attention to the contribution of Italian research groups in this field, the fabrication techniques, and the current status of the clinical trials.

Engineering Extracellular Matrix Proteins to Enhance Cardiac Regeneration After Myocardial Infarction

Engineering microenvironments for accelerated myocardial repair is a challenging goal. Cell therapy has evolved over a few decades to engraft therapeutic cells to replenish lost cardiomyocytes in the left ventricle. However, compelling evidence supports that tailoring specific signals to endogenous cells rather than the direct integration of therapeutic cells could be an attractive strategy for better clinical outcomes. Of many possible routes to instruct endogenous cells, we reviewed recent cases that extracellular matrix (ECM) proteins contribute to enhanced cardiomyocyte proliferation from neonates to adults. In addition, the presence of ECM proteins exerts biophysical regulation in tissue, leading to the control of microenvironments and adaptation for enhanced cardiomyocyte proliferation. Finally, we also summarized recent clinical trials exclusively using ECM proteins, further supporting the notion that engineering ECM proteins would be a critical strategy to enhance myocardial repair without taking any risks or complications of applying therapeutic cardiac cells.

Surgeons should be wise when choosing a material to repair heart defects

Various types of prosthetic materials are available for usage in cardiac surgery to repair heart defects. PTFE, Dacron, and bovine pericardial are some examples of the most used materials for this purpose. In this article, the authors describe the potential failure of the CorMatrix®.

Recurrent ventricular septal defect following closure CorMatrix: A case report

Ventricular septal ruptures are an uncommon complication following acute myocardial infarction. Operative repair, utilizing a patch for closure of the defect, is the primary treatment modality to achieve hemodynamic stability. The use of an extracellular matrix derived from small intestinal submucosa as a scaffold for tissue repair is becoming increasingly common. Here, we present the case of a 58-year-old female found to have a ventricular septal rupture and posterior left ventricular aneurysm following late presentation after a myocardial infarction that required operative repair with a CorMatrix patch. Upon readmission for dyspnea and poor exercise tolerance several months later, the patch was subsequently found to have near-completely reabsorbed. There is a paucity of long-term outcomes data following the use of CorMatrix for septal defects, with rare reports of such reabsorption. Further study is required to identify the incidence and implications of such findings.

Evaluation of Explanted CorMatrix Tyke Extracardiac Patches in Infants With Congenital Heart Disease

BACKGROUND

Animal data demonstrate that intracardiac patches of decellularized porcine small intestine submucosa (CorMatrix; CorMatrix Cardiovascular, Atlanta, GA) become repopulated with native cells, suggesting the possibility of a substrate for regenerative tissue in humans. Although human studies have not demonstrated this regenerative property with intracardiac patches, it is possible that other environments may better promote native cell repopulation. We report a prospective series of explanted CorMatrix extracardiac patches placed in infants with congenital heart disease.

METHODS

CorMatrix Tyke patches were used in pulmonary artery patch closure during the Norwood procedure. The patch material was explanted as part of the hemi-Fontan procedure. Specimens were analyzed with the use of hematoxylin and eosin, Movat pentachrome, and trichrome stains.

RESULTS

Of the 11 implantations, 9 specimens were explanted. One patient did not survive to hemi-Fontan procedure. One patient's patch was removed, but not analyzed. Acellular material, chronic inflammation, fibrosis, and foreign body giant cell reaction was seen in all explanted patches. No explanted CorMatrix Tyke material demonstrated evidence of ingrowth of native endothelial tissue at a median of 4.9 months in vivo.

CONCLUSIONS

CorMatrix Tyke patch material, placed as a pulmonary artery patch in an extracardiac position, remained pliable and mostly free of calcification. However, these patches did not show evidence of native endothelial tissue at a median of 4.9 months in vivo.

Mitral Valve Replacement in Pediatrics Using an Extracellular Matrix Cylinder Valve: A Case Series

Mitral valve replacement (MVR) in children under 2 years is associated with significant morbidity and mortality. Decellularized porcine intestinal submucosa is a commercially available formulation of an extracellular matrix (ECM) with an indication for cardiac tissue repair. The present study reports our experience using ECM cylinder valves in patients for MVR. A retrospective review of patients under 2 years who underwent ECM custom-made cylinder mitral valve (ECM-MV) replacement was performed. Clinical, demographic, operative and post-operative follow-up data, including serial echocardiographic data are presented. Eight patients (age 5.6 ± 1.6 months; weight: 6.0 ± 1.1 kg) were identified who underwent ECM-MVR. There was one in-hospital death and no major neurological events. Six patients underwent replacement of their cylinder valve with either a Melody valve inside the ECM-MVR (n = 3), a mechanical valve (n = 2), or a decellularized bovine pericardial cylinder valve (n = 1). The mean time to replacement surgery was 8.4 ± 2.6 months after ECM-MV. The indications for replacement of ECM-MV included mitral stenosis/regurgitation (n = 4) or dehiscence (n = 2). One remaining patient is 24 months from ECM-MV, with trivial regurgitation and no stenosis. Mitral valve creation using ECM is an option for MVR in pediatrics, avoiding anticoagulation, and provides a suitable construct for later placement of a Melody valve, extending surgical and non-surgical options. However, the durability of the native ECM-MV in the mitral position is concerning considering the high re-intervention rate in a relatively short time period. Further studies are needed to determine the longer-term outcomes of this valve in this complex patient population.

Inducing Endogenous Cardiac Regeneration: Can Biomaterials Connect the Dots?

Heart failure (HF) after myocardial infarction (MI) due to blockage of coronary arteries is a major public health issue. MI results in massive loss of cardiac muscle due to ischemia. Unfortunately, the adult mammalian myocardium presents a low regenerative potential, leading to two main responses to injury: fibrotic scar formation and hypertrophic remodeling. To date, complete heart transplantation remains the only clinical option to restore heart function. In the last two decades, tissue engineering has emerged as a promising approach to promote cardiac regeneration. Tissue engineering aims to target processes associated with MI, including cardiomyogenesis, modulation of extracellular matrix (ECM) remodeling, and fibrosis. Tissue engineering dogmas suggest the utilization and combination of two key components: bioactive molecules and biomaterials. This chapter will present current therapeutic applications of biomaterials in cardiac regeneration and the challenges still faced ahead. The following biomaterial-based approaches will be discussed: Nano-carriers for cardiac regeneration-inducing biomolecules; corresponding matrices for their controlled release; injectable hydrogels for cell delivery and cardiac patches. The concept of combining cardiac patches with controlled release matrices will be introduced, presenting a promising strategy to promote endogenous cardiac regeneration.

Failure of Cellularization of Ventriculotomy Patch Leading to Right Ventricular Pseudoaneurysm

Enlargement of the bulboventricular foramen (BVF) in double-inlet left ventricle or the ventricular septal defect (VSD) in tricuspid atresia with transposition of the great arteries is one approach for prevention or treatment of systemic ventricular outflow obstruction. Most often, BVF/VSD restriction is bypassed preemptively or addressed directly at the time of Glenn/Fontan procedures as part of staged univentricular palliation. We describe a patient who underwent enlargement of a restrictive VSD during Fontan completion and subsequently presented with an asymptomatic pseudoaneurysm of the right ventricle at the ventriculotomy site.

Initial 2-year results of CardioCel® patch implantation in children

OBJECTIVES

We present the initial 2-year results of CardioCel® patch (Admedus Regen Pty Ltd, Perth, WA, Australia) implantation in paediatric patients with congenital heart diseases.

METHODS

This was a single-centre retrospective study with prospectively collected data of all patients aged 18 years and under operated for congenital heart disease. The patch was introduced in 2014, with clinical practice committee approval and a special consent in case of an Ozaki procedure. Standard follow-up was performed with systematic clinical exams and echocardiograms. In case of reoperation or graft failure, the patch was removed and sent for a histological examination.

RESULTS

Between March 2014 and April 2016, 101 patients had surgical repair using a CardioCel patch. The mean age was 22 (±36.3) months, and the mean weight was 9.7 (±10.3) kg. No infections and no intraoperative implantation difficulties were associated with the patch. The median follow-up period was 212 (range 4-726) days. The overall 30-day postoperative mortality was 3.8% (n = 4), none of which were related to graft failure. Five children were reoperated because of graft failure, 4 of whom had the patch implanted for aortic and were aged less than 10 days. The indications for patch implantation in the aortic position were aortopulmonary window, truncus arteriosus, coarctation and aortic arch hypoplasia repair. The median time between the first and the second operation for graft failure was 245 (range 5-480) days.

CONCLUSIONS

Our experience shows that the patch is well tolerated in the septal, valvar and pulmonary artery positions. However, we experienced graft failures in infants in the aortic position.

Clinical Trial Design for Investigational Cardio-Regenerative Therapy

Human trials of cardio-regenerative biologic therapies are being performed worldwide to address a growing, unmet need for durable treatments of cardiovascular disease. A well-constructed clinical trial design for these novel therapies requires careful attention to defining a clear hypothesis, a patient population, and anticipated outcomes. The scope of screening, method of randomization, blinding approach, data monitoring, and statistical analysis plan are the foundational elements that must be addressed in any clinical trial. Although the experience of human trials involving extracellular matrix constructs for cardiovascular disease treatment is limited, numerous lessons have been learned in the field of cell therapy that are translatable across all biologic treatment options. Future progress in this field may include testing combinations of cells, gene-transfer agents, and matrix and identifying treatment responders versus nonresponders.

Porcine Small Intestinal Submucosa May Be a Suitable Material for Norwood Arch Reconstruction

BACKGROUND

Norwood palliation typically requires patch augmentation of the ascending aorta and aortic arch. Patients having undergone Norwood palliation are at risk of recurrent arch obstruction, the risk of which may be affected by the type of patch material used at the time of Norwood palliation. We sought to determine the freedom from neoaortic arch reintervention and overall survival in patients who underwent Norwood palliation utilizing porcine small intestinal submucosa (PSIS) as the patch material.

METHODS

Retrospective chart review was performed to identify patients who underwent a Norwood operation utilizing PSIS material at our institution. Cardiac diagnosis, age at surgery, shunt type, need for reintervention, and outcome (survival, transplant, and death) were evaluated.

RESULTS

Forty-four patients had PSIS material utilized for arch reconstruction at the time of Norwood palliation. There were only five neoaortic arch reinterventions in 4 patients (11.4%). An additional 10 reinterventions, unrelated to the PSIS patch, were performed, including five shunt revisions and five branch pulmonary artery interventions. There were 3 deaths, and 5 patients underwent transplantation. Median follow-up was 387.5 days (range, 4 to 1,513).

CONCLUSIONS

Freedom from neoaortic arch reintervention and survival after Norwood palliation with PSIS patch material is promising. The PSIS appears noninferior and may be an appropriate tissue choice for Norwood palliation. Studies with longer follow-up are needed to determine the rate of neoaortic reintervention over time.

Regenerative Therapy for Patients with Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, affecting 1 in 100 babies. Among CHDs, single ventricle (SV) physiologies, such as hypoplastic left heart syndrome and tricuspid atresia, are particularly severe conditions that require multiple palliative surgeries, including the Fontan procedure. Although the management strategies for SV patients have markedly improved, the prevalence of ventricular dysfunction continues to increase over time, especially after the Fontan procedure. At present, the final treatment for SV patients who develop heart failure is heart transplantation; however, transplantation is difficult to achieve because of severe donor shortages. Recently, various regenerative therapies for heart failure have been developed that increase cardiomyocytes and restore cardiac function, with promising results in adults. The clinical application of various forms of regenerative medicine for CHD patients with heart failure is highly anticipated, and the latest research in this field is reviewed here. In addition, regenerative therapy is important for children with CHD because of their natural growth. The ideal pediatric cardiovascular device would have the potential to adapt to a child's growth. Therefore, if a device that increases in size in accordance with the patient's growth could be developed using regenerative medicine, it would be highly beneficial. This review provides an overview of the available regenerative technologies for CHD patients.

Is Decellularized Porcine Small Intestine Sub-mucosa Patch Suitable for Aortic Arch Repair?

Introduction: We reviewed our experience with decellularized porcine small intestine sub-mucosa (DPSIS) patch, recently introduced for congenital heart defects. Materials and Methods: Between 10/2011 and 04/2016 a DPSIS patch was used in 51 patients, median age 1.1 months (5 days to 14.5 years), for aortic arch reconstruction (45/51 = 88.2%) or aortic coarctation repair (6/51 = 11.8%). All medical records were retrospectively reviewed, with primary endpoints interventional procedure (balloon dilatation) or surgery (DPSIS patch replacement) due to patch-related complications. Results: In a median follow-up time of 1.5 ± 1.1 years (0.6-2.3years) in 13/51 patients (25.5%) a re-intervention, percutaneous interventional procedure (5/51 = 9.8%) or re-operation (8/51 = 15.7%) was required because of obstruction in the correspondence of the DPSIS patch used to enlarge the aortic arch/isthmus, with median max velocity flow at Doppler interrogation of 4.0 ± 0.51 m/s. Two patients required surgery after failed interventional cardiology. The mean interval between DPSIS patch implantation and re-intervention (percutaneous procedure or re-operation) was 6 months (1-17 months). While there were 3 hospital deaths (3/51 = 5.9%) not related to the patch implantation, no early or late mortality occurred for the subsequent procedure required for DPSIS patch interventional cardiology or surgery. The median max velocity flow at Doppler interrogation through the aortic arch/isthmus for the patients who did not require interventional procedure or surgery was 1.7 ± 0.57 m/s. Conclusions: High incidence of re-interventions with DPSIS patch for aortic arch and/or coarctation forced us to use alternative materials (homografts and decellularized gluteraldehyde preserved bovine pericardial matrix).

Calcific Degeneration of CorMatrix 4 Years After Bicuspidization of Unicuspid Aortic Valve

We report the long-term outcomes of a 12-year-old boy who underwent bicuspidization of a severely stenotic unicuspid aortic valve with CorMatrix small intestinal submucosal extracellular matrix (CorMatrix Cardiovascular, Roswell, GA). CorMatrix supported favorable immediate surgical and echocardiographic outcomes and maintained stable growing functional dynamics for 2 years. At 52.5 months in situ, however, the valve failed with severe calcification, fibrosis, and retraction necessitating a redo operation. Reconstructive operations with CorMatrix are feasible, but this result questions its capacity for constructive remodeling in left-sided valve repair.

Efficacy of an Extracellular Matrix in Systemic Loading Conditions in Congenital Heart Surgery

Extracellular matrices (ECM) are commonly used to repair congenital heart defects; however, there is a lack of literature pertaining to outcomes with ECM use in high-pressure conditions. Between 2011 and 2014, a total of 202 patients underwent congenital heart disease repair using the ECM placed in a systemic pressure condition. The operative sites included: defects in the ventricular septum, mitral valve, aortic valve, ascending aorta, and aortic arch. Patients were followed and evaluated for mortality and reoperations due to loss of ECM integrity. Echocardiograms were evaluated for graft malfunction such as aneurysmal dilation, VSD formation, valve malfunction, or outflow tract obstruction. Patients were followed for an average of 1492 days (Median = 1583). Out of the 202 patients, 7 (3.5%) died due to complications unrelated to ECM, and 10 (5%) underwent reoperations due to complications of ECM integrity. Reoperations were as follows: two of 6 patients receiving aortic leaflet replacement required reoperation for leaflet failure; four of 12 patients receiving mitral valve leaflet repairs required reoperation for leaflet failure; and four of 142 patients with VSD repair required reoperation for residual shunting. The average time to reoperation was 208 days. There were no outflow tract obstructions or aneurysmal dilatations observed. This modern case series suggests that the ECM is efficacious and sustainable under systemic conditions in congenital heart defect repair. However, concerns remain about the use of ECM in aortic valve repair and infant mitral valve repair. Further studies are needed to evaluate long-term ECM integrity.

Congenital aortic valve repair using CorMatrix® : A histologic evaluation

BACKGROUND

The reconstruction of heart valves provides substantial benefits, particularly in the pediatric population. We present our experience using decellularized extracellular matrix (dECM, CorMatrix^® ) for aortic valve procedures.

METHODS

We retrospectively reviewed the case histories of 6 patients (aged from 2 months - 14 years) who underwent surgery for severe aortic valve stenosis (n = 4) or regurgitation (n = 2). Aortic valve repair was performed on all patients using dECM as a leaflet replacement or leaflet extension. Follow-ups were performed using echocardiography. Reoperation was necessary in 4 cases, and the dECM was explanted and examined histologically and immunohistochemically.

RESULTS

The early post-operative period was uneventful, and the scaffold fulfilled the mechanical requirements. Significant valve insufficiency developed in 5 patients during the post-operative period (119-441 days postoperatively). In all specimens, only a migration of inflammatory cells was identified, which induced structural and functional changes caused by the chronic inflammatory response.

CONCLUSIONS

Our results suggest a mixed immunological response of remodeling and inflammation following the implantation. The expected process of seeding/migration and remodeling of the bioscaffold into the typical 3-layered architecture were not observed in our explanted specimens.

Biocompatibility of Intensified Decellularized Equine Carotid Arteries in a Rat Subcutaneous Implantation Model and in a Human In Vitro Model

Limited biocompatibility of decellularized scaffolds is an ongoing challenge in tissue engineering. We recently demonstrated that intensified detergent-based decellularization of equine carotid artery (dEAC_intens) removed residual cellular molecules from the scaffold more efficiently than a conventional decellularization (dEAC_con), although this approach did not eliminate its immunogenicity entirely. CCN1 has been shown to improve biocompatibility of dEAC_con in a sheep model. In this study, we tested the biocompatibility of dEAC_intens and dEAC_con with or without CCN1 coating after subcutaneous implantation in rats for up to 12 weeks. Explants were assessed by conventional histopathology and immunostaining for infiltrating M2 macrophages. Moreover, human macrophages derived from monocytes (MDM) or THP-1 cells (THP-derived macrophages [TDM]) were seeded onto dEAC_con and dEAC_intens, and activation was assessed either by cytokine expression or matrix metalloprotease 2 and 7 staining. dEAC_intens showed a significantly reduced inflammatory infiltration (52%; p < 0.0001), as well as an earlier and denser neovascularization (1.4-fold, p < 0.0001) independent of CCN1 coating, which, however, reduced fibrosis exclusively with dEAC_intens (26-53%; p < 0.05). Human MDM seeded for 48 h onto dEAC_intens showed higher transcript levels for anti-inflammatory IL-10 (2.3-fold), proinflammatory TNFα (2.2-fold), and macrophage/monocyte recruiting MIP1α (3.5-fold; all p < 0.05) and MCP (2.7-fold; p < 0.01), whereas 1.92-fold more TDM on dEAC_intens showed staining for MMP2 (p > 0.001). Thus, although being advantageous in regard to fibrosis, CCN1 coating of dEAC_intens does not appear to be necessary for further improving dEAC_intens excellent biocompatibility in rats. In humans, the unspecific cellular immune response toward dEAC_intens seemed to be more complex, but generally comparable to the mild acute inflammatory tissue reaction with high remodeling activity as observed after rat subcutaneous implantation.

Right ventricular function after repair of tetralogy of Fallot: a comparison between bovine pericardium and porcine small intestinal extracellular matrix

BACKGROUND

The porcine small intestinal extracellular matrix reportedly has the potential to differentiate into viable myocardial cells. When used in tetralogy of Fallot repair, it may improve right ventricular function. We evaluated right ventricular function after repair of tetralogy of Fallot with extracellular matrix versus bovine pericardium.

METHOD

Subjects with non-transannular repair of tetralogy of Fallot with at least 1 year of follow-up were selected. The extracellular matrix and bovine pericardium groups were compared. We used three-dimensional right ventricular ejection fraction, right ventricle global longitudinal strain, and tricuspid annular plane systolic excursion to assess right ventricular function.

RESULTS

The extracellular matrix group had 11 patients, whereas the bovine pericardium group had 10 patients. No differences between the groups were found regarding sex ratio, age at surgery, and cardiopulmonary bypass time. The follow-up period was 28±12.6 months in the extracellular matrix group and 50.05±17.6 months in the bovine pericardium group (p=0.001). The mean three-dimensional right ventricular ejection fraction (55.7±5.0% versus 55.3±5.2%, p=0.73), right ventricular global longitudinal strain (-18.5±3.0% versus -18.0±2.2%, p=0.44), and tricuspid annular plane systolic excursions (1.59±0.16 versus 1.59±0.2, p=0.93) were similar in the extracellular matrix group and in the bovine pericardium group, respectively. Right ventricular global longitudinal strain in healthy children is reported at -29±3% in literature.

CONCLUSION

In a small cohort of the patients undergoing non-transannular repair of tetralogy of Fallot, there was no significant difference in right ventricular function between groups having extracellular matrix versus bovine pericardium patches followed-up for more than 1 year. Lower right ventricular longitudinal strain noted in both the groups compared to healthy children.

Early complications of biologic extracellular matrix patch after use for femoral artery repair

BACKGROUND

The CorMatrix (CorMatrix Cardiovascular, Roswell, Ga) biologic extracellular patch derived from porcine small intestinal mucosa provides a biologic scaffold for cellular ingrowth and eventual tissue regeneration. It has been used in a variety of applications, including cardiac and vascular repair procedures.

METHODS

CorMatrix was used as a patch arterioplasty for femoral artery repair in conjunction with endarterectomy for seven separate procedures in six patients (one patient underwent staged, bilateral femoral procedures).

RESULTS

Patients were a median age of 67 years (interquartile range, 3.6 years). Six of seven procedures (86%) were performed on male patients. There were no operative deaths. Three of seven procedures (43%) resulted in significant early complications. Two procedures (29%) resulted in catastrophic biologic extracellular matrix patch disruption (11 and 19 days after initial procedure), requiring emergency exploration, patch removal, and definitive repair with vein patch arterioplasty. Both patches demonstrated an absence of growth on culture. One procedure (14%) resulted in groin pseudoaneurysm formation. Use of the CorMatrix patch was suspended upon recognition of significant complications.

CONCLUSIONS

Use of CorMatrix patch in the femoral artery position demonstrates a high incidence of early postoperative complications, including catastrophic patch disruption and pseudoaneurysm formation.