Ultrastructural evidence of myocardial capillary remodeling in peripartum cardiomyopathy

The etiology of peripartum cardiomyopathy (PPCM) is not well understood. Potential causal mechanisms include infection, autoimmune disease, and abnormal response to the hemodynamic stress of pregnancy. Recently it was shown that the development of PPCM in an experimental model is associated with the generation of a cleaved antiangiogenic and proapoptotic 16-kDa form of the nursing hormone prolactin, which impairs the cardiac capillary network and its function. The purpose of this study was to evaluate the ultrastructure of the myocardium in a patient with PPCM and in a comparative group of patients and to identify structural characteristics that may predispose to myocardium dysfunction.

A 28-year-old woman with PPCM had fulminant heart failure leading to the implantation of a biventricular assist device, but no myocarditis was found on histological examination of her myocardial tissue. An ultrastructural study of myocardial tissue taken from three patients (mean age: 22 years, 2 females) with fulminant heart failure not related to PPCM (2 myocarditis, 1 dilated cardiomyopathy) served as a comparison. The ultrastructural analysis revealed the presence of small capillary damage. Vascular lumen occlusion, endothelial cell remodeling, and apoptosis with the appearance of mast cells, plasma cells, and preadipocytes were the most characteristic features of the damaged myocardial tissue with secondary interstitial fibrosis. No vascular pathology of cardiac capillaries was observed in the comparative group.

A myocardial tissue study in PPCM revealed ultrastructural remodeling of small capillaries with the presence of endothelial cell apoptosis and impairment of the microcirculation.