Natural Tissue Engineering Inside a Ventricular Septum Defect Occluder
Eighteen days after having received conservative treatment for a myocardial infarction, a 65-year-old patient developed acute right heart failure caused by a ventricular septal rupture. Progressive multiorgan failure contraindicated open heart surgery. Therefore, we implanted a ventricular septal defect occluder via a venous approach as an emergency intervention, thereby achieving stabilization of the patient within 24 hours. After another 6 weeks, an aneurysmectomy was planned because a remarkable aneurysm of the anterior wall, including the part of the septum in which the occluder was located, was detected by echocardiography and magnetic resonance imaging. During open heart surgery, the occluder was removed (Figure 1), and a Dor procedure was performed in addition to aortocoronary bypass grafting.
After accurately cutting through the occluder, an immunohistochemistry study was performed (Figure 2). Tissue formation was observed on the nitinol arms of the occluder. The boundaries of this newly formed tissue were mainly defined by smooth muscle cells. The portion of tissue extending to the left ventricle was more multilayered and consequently wider than that on the right ventricular side. The space between the smooth muscle layers was filled with numerous macrophages, fibroblasts, myofibroblasts, lymphocytes, and most interestingly, vascular structures. Angiogenesis was pronounced, and the presence of numerous macrophages and lymphocytes suggested that active inflammatory processes had occurred during the formation of this viable tissue.
Tissue formation within the occluder was not observed in the area of the septal infarct. Therefore, we assumed that the different cells had not migrated per continuitatem from the septal scar tissue but rather had been derived from the circulating blood. The results presented show for the first time that within a short time, naturally differentiated tissue formation is possible in the heart.
↵*The first 2 authors contributed equally to this work.