Patch materials for right ventricular outflow reconstruction: past, present, and future

Surgical Patching in Congenital Heart Disease: The Role of Imaging and Modelling

In congenital heart disease, patches are not tailored to patient-specific anatomies, leading to shape mismatch with likely functional implications. The design of patches through imaging and modelling may be beneficial, as it could improve clinical outcomes and reduce the costs associated with redo procedures. Whilst attention has been paid to the material of the patches used in congenital surgery, this review outlines the current knowledge on this subject and isolated experimental work that uses modelling and imaging-derived information (including 3D printing) to inform the design of the surgical patch.

Progress in the application of patch materials in cardiovascular surgery

The cardiovascular patch, served as artificial graft materials to replace heart or vascular tissue defect, is still playing a key role in cardiovascular surgeries. The defects of traditional cardiovascular patch materials may determine its unsatisfactory long-term effect or fatal complications after surgery. Recent studies on many new materials (such as tissue engineered materials, three-dimensional printed materials, etc) are being developed. Patch materials have been widely used in clinical procedures of cardiovascular surgeries such as angioplasty, cardiac atrioventricular wall or atrioventricular septum repair, and valve replacement. The clinical demand for better cardiovascular patch materials is still urgent. However, the cardiovascular patch materials need to adapt to normal coagulation mechanism and durability, promote short-term endothelialization after surgery, and inhibit long-term postoperative intimal hyperplasia, its research and development process is relatively complicated. Understanding the characteristics of various cardiovascular patch materials and their application in cardiovascular surgeries is important for the selection of new clinical surgical materials and the development of cardiovascular patch materials.

A Comparison of Vessel Patch Materials in Tetralogy of Fallot Patients Using Virtual Surgery Techniques

Tetralogy of Fallot (ToF) is characterized by stenosis causing partial obstruction of the right ventricular outflow tract, typically alleviated through the surgical application of a vessel patch made from a biocompatible material. In this study, we use computational simulations to compare the mechanical performance of four patch materials for various stenosis locations. Nine idealized pre-operative ToF geometries were created by imposing symmetrical stenoses on each of three anatomical sub-regions of the pulmonary arteries of three patients with previously repaired ToF. A virtual surgery methodology was implemented to replicate the steps of vessel de-pressurization, surgical patching, and subsequent vessel expansion after reperfusion. Significant differences in patch average stress (p < 0.001) were found between patch materials. Biological patch materials (porcine xenopericardium, human pericardium) exhibited higher patch stresses in comparison to synthetic patch materials (Dacron and PTFE). Observed differences were consistent across the various stenosis locations and were insensitive to patient anatomy.

Influence of the perfusion bioreactor on Stratified and Distributed approaches for multilayered tissue engineering on biodegradable scaffolds

Despite wide use and approval of poly lactic-coglycolic acid (PLGA) for surgical applications, there have been very few studies on tissue constructions that mimic physiological multilayer structures by combining PLGA scaffolds with tissue engineering. In our study, we developed a bioreactor system to maintain, and to train two types of three-layered vascular-like structures. Then we examined how the perfusion conditions and different tissue engineering approaches affected the formation of the layered structure and degradation of the PLGA scaffolds. In the proposed Distributed Method, the cells were seeded layer by layer on a single scaffold, using spheroids bigger than scaffold fiber gaps and we achieved the higher cell density compared with the Stratified Method where we stacked three PLGA sheets seeded with individual vascular cell types. At the histological level, scaffold degradation was more prominent in the bioreactor compared to the same time interval in vivo. In addition, the faster flow accelerated the decomposition of PLGA fibers. Moreover, bioreactor perfusion culture at lower flow rates could balance cell adhesion and survival, improve the cell density and promote self-organization of multilayer structure with desirable rate of PLGA scaffolds degradation.

Biological Characterization of Human Autologous Pericardium Treated with the Ozaki Procedure for Aortic Valve Reconstruction

Background: The Ozaki procedure is an innovative surgical technique aiming at reconstructing aortic valves with human autologous pericardium. Even if this procedure is widely used, a comprehensive biological characterization of the glutaraldehyde (GA)-fixed pericardial tissue is still missing. Methods: Morphological analysis was performed to assess the general organization of pericardium subjected to the Ozaki procedure (post-Ozaki) in comparison to native tissue (pre-Ozaki). The effect of GA treatment on cell viability and nuclear morphology was then investigated in whole biopsies and a cytotoxicity assay was executed to assess the biocompatibility of pericardium. Finally, human umbilical vein endothelial cells were seeded on post-Ozaki samples to evaluate the influence of GA in modulating the endothelialization ability in vitro and the production of pro-inflammatory mediators. Results: The Ozaki procedure alters the arrangement of collagen and elastic fibers in the extracellular matrix and results in a significant reduction in cell viability compared to native tissue. GA treatment, however, is not cytotoxic to murine fibroblasts as compared to a commercially available bovine pericardium membrane. In addition, in in vitro experiments of endothelial cell adhesion, no difference in the inflammatory mediators with respect to the commercial patch was found. Conclusions: The Ozaki procedure, despite alteration of ECM organization and cell devitalization, allows for the establishment of a noncytotoxic environment in which endothelial cell repopulation occurs.

Emerging Functional Biomaterials as Medical Patches

Medical patches have been widely explored and applied in various medical fields, especially in wound healing, tissue engineering, and other biomedical areas. Benefiting from emerging biomaterials and advanced manufacturing technologies, great achievements have been made on medical patches to evolve them into a multifunctional medical device for diverse health-care purposes, thus attracting extensive attention and research interest. Here, we provide up-to-date research concerning emerging functional biomaterials as medical patches. An overview of the various approaches to construct patches with micro- and nanoarchitecture is presented and summarized. We then focus on the applications, especially the biomedical applications, of the medical patches, including wound healing, drug delivery, and real-time health monitoring. The challenges and prospects for the future development of the medical patches are also discussed.

Long-term Results Using Glutaraldehyde-treated Homograft Pericardium in Congenital Heart Surgery

BACKGROUND

This study reports the long-term outcomes using glutaraldehyde-treated cryopreserved homograft pericardium (CPH) in neonates, infants, children, and young adults undergoing congenital cardiac surgery.

METHODS

A retrospective review was performed of all patients at a single institution (Rady Children's Hospital, San Diego, CA) who had undergone surgical implantation with CPH between 2006 and 2016. The study identified 134 consecutive patients who underwent implantation of a total of 276 patches. The baseline demographic characteristics, primary cardiac diagnosis, surgical characteristics, operative reports, and postoperative catheterization and reoperation reports were analyzed. The use of CPH was categorized by specific anatomic insertion site.

RESULTS

The median age at patch implantation was 1.47 years (range, 1 day to 31.6 years). The numbers and locations of patch use were 124 for pulmonary arterial repair, 57 for repair of the aorta, 49 for septal repair, and 43 at other sites. At a median follow-up of 5.29 years, 9 patients had died (6.7%), but none of those deaths were related to CPH. Twelve patients (8.96%) underwent reoperations, and 18 patients (13.4%) underwent catheter interventions at sites of CPH implantation. The 10-year freedom from patch-induced reoperation and catheter intervention rates were 88.5% and 86.9%, respectively. Overall patch failure-free survival was 85.8% and 79.0% at 5 and 10 years, respectively.

CONCLUSIONS

The use of CPH patch in the surgical correction of congenital heart disease is effective and durable, as evidenced by the low reintervention rates. These results are comparable to the early and midterm outcomes of other similarly used surgical patches..

Outcome of 40 consecutive cases of modified Ross procedure using novel Dacron valved conduit

OBJECTIVE

The Ross procedure is an established option for aortic valve disease in children. Due to limited availability of pulmonary homograft, we devised a novel technique for right ventricular outflow tract (RVOT) reconstruction by preparing indigenous Dacron valved conduit.

METHODS

Forty consecutive cases of modified Ross procedure done at our center (2013-2018) were analyzed. Thirty-seven patients (95%) were followed up with median duration of 2.5 (0.08-5.5) years. Median age was 12 (5-39) years. Nineteen (47.5%) patients had rheumatic aortic valve disease, while 19 (47.5%) had congenital aortic valve disease. Aortic root replacement with pulmonary autograft was performed in all patients. Dacron conduit for RVOT reconstruction was used with on table sewn bileaflet valve using Dacron patch (n = 22), expanded polytetrafluoroethylene (ePTFE) membrane (n = 10), bioprosthetic valve (n = 4), and pericardium (n = 4). Additional surgical procedures included mitral valve repair (n = 10), septal myectomy (n = 2), ascending aorta replacement (n = 1), ruptured sinus of valsalva (RSOV) repair (n = 1), and ventricular septal defect (VSD) closure (n = 1).

RESULTS

There was one in-hospital mortality while one late death occurred at 3.5 years postoperatively. The neo-aortic valve regurgitation on echocardiographic evaluation at last follow-up was trivial (n = 28), mild (n = 7), and moderate (n = 2). Mild RVOT obstruction was present in 8 patients while 18 patients had mild pulmonary regurgitation. No patient required reintervention during follow-up.

CONCLUSION

Our early results of modified Ross procedure are encouraging, however, long-term follow-up is required.