Enlargement of the aortic annulus using a heterologous pericardial patch is performed extensively in patients with a narrow aortic annulus and has become a simple and reproducible technique for many cardiac surgeons[
2]. In a long-term follow-up survey, Celiento et al. reported that in patients with a small aortic annulus, enlargement of the aortic annulus is a safe and effective procedure that does not cause late aneurysm formation or dilatation of the aortic root[
3]. Although it is possible for an aneurysm to form in a heterologous pericardial patch and go undetected, there have been no reports of rupture and late aneurysm formation after heterologous pericardial patch repair of aortic annulus enlargement in adults. However, a few cases of aneurysm formation after bovine pericardial patch repair have been reported in children[
5,
6]. A patient who underwent a Norwood procedure with Sano right ventricle-to-pulmonary artery shunt for hypoplastic left heart syndrome was reported to develop a pseudoaneurysm in the proximal portion of the Sano anastomosis caused by degeneration of the bovine pericardium[
5]. Moreover, a neoaortic aneurysm constructed with native great vessel and bovine pericardial patch after third-stage palliation for hypoplastic left heart has been reported[
6]. Histopathological changes evident in disruptions of elastic laminae suggest an inherent defect in the patch material rather than in the method of fixation or surgical technique. In vascular surgery, there have been sporadic reports of pseudoaneurysm formation of unclear etiology with bovine pericardial patches[
7]. Therefore, it may be necessary to perform periodic CT scans to detect pseudoaneurysm-related changes.
The bovine glutaraldehyde-fixed pericardial patch may be responsible for the low rate of pseudoaneurysm formation; anticalcification technology and acellular pure collagen may provide host-cell migration and proliferation, accelerated endothelialization, and tissue regeneration[
7]. However, in our case, the tear in the equine pericardial patch with thinning developed adjacent to the ascending aortic vascular prosthesis. This may indicate that a frictional force on the pericardial patch between the vascular prosthesis and the suture line led to degenerative changes. Considering this possibility, we used a double-layered patch consisting of a bovine pericardial patch reinforced with a Hemashield patch to improve the strength and durability of the repair.