OBJECTIVETo investigate the histopathological features of primary restrictive cardiomyopathy (PRCM).

METHODSNine extransplanted hearts from heart transplantation recipients were examined. Gross and histopathological findings were observed, photographed and final pathological diagnosis was compared to clinical diagnosis. The myocardial ultrastructure changes were determined using transmission electron microscopy.

RESULTSThe hallmark pathologic feature of PRCM was distinguished by myocardial cell degeneration and hyperplastic collagen fibrils around the myocardial cells.Fibrosis was severer in left ventricle free wall than in ventricular septum and right ventricle. The degree of myocardial cell degeneration and poloidal disorder were severer in patients with reduced ejection fraction (EF) than in patients with preserved EF. Transmission electron microscope evidenced severe interstitial fibrosis, myofibrillar changes of sarcomere structure, abnormalities both on intercalated disc number and distribution.

CONCLUSIONSPRCM is characterized by hyperplastic collagen fibrils around the cardiomyocytes. Fibrosis is severer in left ventricle than in right ventricle. Sarcomere dysplasia is the main cause of PRCM, and ultrastructural examination is helpful for PRCM diagnosis.

Cardiomyopathy, Restrictive ; surgery ; Fibrosis ; Heart Transplantation ; Heart Ventricles ; Humans ; Myocardium ; pathology ; Myocytes, Cardiac ; Sarcomeres

PURPOSE: The arrhythmogenic effect of stem cells transplantation (SCT) in an infarct myocardium is still unknown. We investigated arrhythmogenicity of SCT in rat cryo-infarct model. MATERIALS AND METHODS: In rat cryo-infarct model, bone marrow mononuclear stem cells (MNSC, 1 x 10(7) cells) were transplanted into the infarct border zone (BZ) of the LV epicardium. We compared the optical mapping and inducibility of ventricular tachycardia/fibrillation (VT/VF) among normal (n=5), cryo-infarct (n=6), and SCT rats (n=6). RESULTS: The VT/VF inducibility was higher in the cryo- infarct (47.2%, p=0.001) and SCT groups (34.6%, p=0.01) than in the normal group (12.8%). The induced VT/VF episodes persisted for more than 2 minutes in 4.3%, 26.4% and 17.3% in the normal, cryo-infarct and SCT group, respectively. In the SCT group, the action potential duration at 70% was shorter at the SCT site than the BZ during SR (75.2 +/- 8.1 vs. 145.6 +/- 4.4 ms, p=0.001) and VT (78.2 +/- 13.0 vs. 125.7 +/- 21.0 ms, p= 0.001). Conduction block was observed at the SCT site and BZ during VT. However, no reentry or ectopic foci were observed around the SCT sites. CONCLUSION: The electrical conduction was improved by SCT without evidence of augmentation of arrhythmia in the rat cryo-infarct model.
Action Potentials ; Animals ; Arrhythmias, Cardiac/*etiology ; Bone Marrow Transplantation/*adverse effects ; Disease Models, Animal ; Electric Conductivity ; Heart Ventricles/pathology/transplantation ; Hematopoietic Stem Cell Transplantation/*adverse effects ; Myocardial Infarction/pathology/*surgery ; Rats ; Rats, Sprague-Dawley