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

Entire Mitral Valve Reconstruction Using Porcine Extracellular Matrix: Adding a Ring Annuloplasty

PURPOSE

This study investigated the implications of inserting a flexible annuloplasty ring after reconstructing the entire mitral valve in a porcine model using a previously investigated tube graft design made of 2-ply small intestinal submucosa extracellular matrix (CorMatrix®).

METHODS

An acute model with eight 80-kg pigs, each acting as its own control, was used. The entire mitral valve was reconstructed with a 2-ply small intestinal submucosa extracellular matrix tube graft (CorMatrix®). Subsequently, a Simulus® flexible ring was inserted. The characterization was based on mitral annular geometry and valvular dynamics with sonomicrometry and echocardiography.

RESULTS

After adding the ring annuloplasty, the in-plane annular dynamics were more constant throughout the cardiac cycle compared to the reconstruction alone. However, the commissure-commissure distance was statistically significantly decreased [35.0 ± 3.4 mm vs. 27.4 ± 1.9 mm, P < 0.001, diff =  - 7.6 mm, 95% CI, - 9.8 to (-5.4) mm] after ring insertion, changing the physiological annular D-shape into a circular shape which created folds at the coaptation zone resulting in a central regurgitant jet on color Doppler.

CONCLUSION

We successfully reconstructed the entire mitral valve using 2-ply small intestinal submucosal extracellular matrix (CorMatrix®) combined with a flexible annuloplasty. The annuloplasty reduced the unphysiological systolic widening previously found with this reconstructive technique. However, the Simulus flex ring changed the physiological annular D-shape into a circular shape and hindered a correct unfolding of the leaflets. Thus, we do not recommend a flexible ring in conjunction with this reconstructive technique; further investigations are needed to discover a more suitable remodelling annuloplasty.

Hybrid Interventions in Congenital Heart Disease

Hybrid interventions in congenital heart disease (CHD) embody the inherent collaboration between congenital interventional cardiology and cardiothoracic surgery. Hybrid approaches to complex and common lesions provide the opportunity to circumvent the limitations of patient size, vascular access, severity of illness, and anatomy that would otherwise be prohibitive to surgical and percutaneous techniques alone. This review describes several important hybrid approaches to interventions in CHD.

Thrombosis Prevention and Anticoagulation Management in the Pediatric Patient with Congenital Heart Disease

Thrombosis is one of the most frequent complications affecting children with congenital heart disease (CHD). Palliative and reparative cardiac surgeries are some of the main players contributing to the thrombosis risk in this patient population. Additional risk factors related to the CHD itself (e.g., cardiac dysfunction, arrhythmias, and polycythemia in cyanotic cardiac disorders) can contribute to thrombogenicity alone or combined with other factors. Thrombotic complications have been recognized as a significant cause of morbidity and mortality in this patient population. Here, we provide an overview of the pathophysiology and risk factors for thrombosis as well as the indications for and use of different anticoagulation, antiplatelet, and thrombolytic agents. In addition, we describe some of most common thrombotic complications and their management in the pediatric CHD population.

Replacement of the Mitral Valve Under One Year of Age: Size Matters

Surgical management of mitral valve disease in neonates and infants is challenging. When repair is no longer feasible, replacement may become inevitable, but should only be considered as an option of last resort due to the remarkably high rate of associated morbidity and mortality. Mechanical valves are the preferred choice in large annuli, while stented conduits seem promising in smaller ones. In patients with a preoperative mitral valve annulus equal or larger than 15-16 mm, an intra-annular placement of the smallest mechanical valve available should be attempted. In patients with smaller annuli, the placement of a stented valved conduit seems to display a lower mortality risk. Supra-annular implantation of prostheses should be reserved for exceptional cases and to those familiar with this technique because of the high rate of associated complications.

Debate - Replacement of the Mitral Valve Under One Year of Age: Mechanical Valves Should Be Used

This article reviews the literature, focusing on publications from the third millennium and the results of mitral valve replacement in children younger than 1 year of age. Special consideration has been given to neonatal and infant valve replacement to provide insights into valve choice and technique. Mitral valve replacement is an important topic because it carries the highest mortality and poorer long-term prognosis than any other valve replacement in children.

Pathological Changes of Adult Mitral Valves after Failed CorMatrix ECM Repair

BACKGROUND AND OBJECTIVES

CorMatrix acts as a tissue scaffold and is intended to promote the proliferation of small vessels and tissue remodeling to replicate normal tissue function.

METHODS

At Temple University Hospital, Philadelphia, PA, USA from 2013 to 2016, CorMatrix material was utilized during mitral valve anterior leaflet augmentation repair in 25 adult patients, and four patients required repeat interventions at 4-12 months (8.25 ± 4.35 months) after the initial repair. This study evaluated the pathological changes in four patients.

RESULTS

Histological examination of the CorMatrix showed matrix degradation in all cases. At 4 months after repair, mixed acute and chronic inflammatory cells that included eosinophils were visible within the matrix, which was more severe around the suture material. Later, the extent of inflammation abated and became more chronic with macrophage dominance. Some macrophages and multinucleated cells were visible deep in the matrix. The neovascularization was limited to the tissue-matrix boundary at early time points; the more mature vessels with dilated lumens extended deeper into the matrix as time increased, combined with some elongated fibroblast-like cells. In addition, marked acute and chronic inflammation with neutrophil and eosinophil infiltrate was identified in the surrounding native tissue at 4 months, especially around the suture material. Marked granulomatous inflammation was identified in all cases, with prominent multinucleated giant cells present at later time points (50%). Immunohistochemical staining for CD68 and CD163 showed prominent M2 macrophages in the CorMatrix and surrounding tissue.

CONCLUSIONS

Our results demonstrated time-dependent changes in failed CorMatrix repaired valves after mitral valve repair, with macrophages and neovascularization in the matrix 12 months after the initial repair.