Autotissue Matrix Patch for Aortic Arch Reconstruction in Congenital Heart Disease—Histology of a Series of Human Explants

Objectives: Different types of patch materials are in use for aortic arch reconstruction in children with aortic arch pathology. The Matrix patch (Autotissue, Berlin) consists of decellularized equine pericardium processed without the use of glutaraldehyde, which is thought to lead to calcification.

Methods: We studied and compared tissue reactions in aortic arch tissue specimen augmented with Matrix patch. Explants were worked up using a uniform protocol with methylmethacrylate and/or paraffin embedding after fixation in formalin. Besides standard histology staining, Kossa stain (for identification of calcifications) and immunohistochemical staining were applied with antibodies specific for muscular, inflammatory, and connective tissue component antigens. Evaluation was focused on the aspects proliferation, calcification, and inflammation.

Results: Four specimens were examined after surgical explantation. Indication for aortic arch repair was hypoplastic aortic arch in three patients and supravalvular aortic stenosis in one. Indication for explantation was distal aortic arch stenosis in three patients and supravalvular aortic stenosis in one. Time interval between implantation and explantation (implant time) was 3 to 52 months.

Superficial endothelialization was demonstrated by immunohistochemistry. All four specimens showed significant tissue proliferation (pseudointima). Only the explant with an implant time of more than 4 years revealed low-grade calcifications. A macrophage wall was seen surrounding the patch material in three of four specimens.

Conclusion: In a small series of Matrix patches used for aortic arch repair, we found significant superficial pseudointima proliferation but only low-grade calcifications in one of four specimens after an implantation time of more than 4 years. However, histology of this patch material shows acceptable results in-short and medium-term explants. Long-term follow-up in larger cohorts is required to determine the definitive patch performance.