Takashi Katashima

High prevalence of chronic myocarditis in dilated cardiomyopathy referred for left ventriculoplasty: expression of tenascin C as a possible marker for inflammation ☆

The objectives of this study were to analyze the incidence of chronic myocarditis in dilated cardiomyopathy and to evaluate the diagnostic value of tenascin C for assessing inflammatory activity in the resected myocardium. Dilated cardiomyopathy patients with chronic myocarditis have a poor clinical outcome despite recent advances in medical treatments. Therefore, a precise diagnosis of inflammatory activity is critical to ensuring appropriate therapy. Tenascin C is an extracellular matrix glycoprotein that plays an important role in tissue remodeling in various heart diseases. Myocardial samples obtained during left ventriculoplasty from 64 patients (50 +/- 13 years, 56 men and 8 women) with dilated cardiomyopathy were examined by immunostaining for tenascin C. Histologic diagnosis was based on the Dallas criteria modified by the International Society and Federation of Cardiology task force. Nine cases (14%) had active myocarditis, 21 (33%) had borderline myocarditis, and 34 (53%) had no myocarditis. Intense tenascin C expression was observed at the site of active inflammation, with abundant cell accumulation, and in organized granulation tissue during the resolving phase but not in scar tissue during the healing phase. The ratio of tenascin C-positive area to the whole myocardium in the active and borderline myocarditis groups was significantly greater than that in the noninflammatory group. These findings suggest a high prevalence of chronic myocarditis in dilated cardiomyopathy patients and that tenascin C may prove to be a useful marker for distinguishing inflammatory cardiomyopathy from other types of dilated cardiomyopathy.

Giant Mitochondria in the Myocardium of a Patient With Mitochondrial Cardiomyopathy Transmission and 3-Dimensional Scanning Electron Microscopy

46-year-old man with a clinical diagnosis of dilated phase of hypertrophic cardiomyopathy was followed up at our hospital for 26 years. His refractory congestive heart failure gradually worsened over several years, and he was unresponsive to conventional medications. He then underwent left ventriculoplasty. Biochemical and genetic investigations of the left ventricular myocardium revealed a novel point mutation in the mitochondrial DNA.1 Scanning electron microscopy can directly observe both the 3-dimensional structure of a cell with high resolution and the 3-dimensional structure of the membrane system using the osmium-dimethyl sulfoxide-osmium method2 to remove the cytoplasmic matrix. Conventional transmission electron microscopy …

Three-Dimensional Architecture of Cardiomyocytes and Connective Tissue in Human Heart Revealed by Scanning Electron Microscopy

Scanning electron microscopy is a useful modality to directly observe the 3-dimensional structures of cells at high resolution. Scanning electron microscopy enables visualization of the surface features of cardiomyocytes after removal of the surrounding connective tissue1 and the connective tissue skeleton after removal of the nonfibrous elements.2 In addition, backscattered electron emission with heavy metal staining3 helps to provide high-quality images of the intracellular architecture of the cardiomyocyte. In this study, we present the 3-dimensional structure of the human left ventricular myocardium from subjects without apparent cardiac …

Markedly increased intracellular lipid droplets and disruption of intercellular junctions in biopsied myocardium from a patient with arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by the progressive replacement of myocardial cells by fat and fibrous tissue. Here we describe the histopathological features of biopsied myocardium from a patient with ARVC. A large amount of adipose tissue was present in the biopsy specimen, and a group of myocardial cells were isolated as an island-like region in the adipose tissue. Electron microscopic examination of cardiomyocytes revealed a large number of intracellular lipid droplets, including some extremely large droplets. Disruptions of the plasma membrane and dissociation of intercellular junctions were associated with discharge of intracellular lipid droplets into the interstitial space. The high accumulation of intracellular lipid droplets may be involved in the pathogenesis of ARVC and may have played an important role in myocardial cell death and progressive replacement of cardiomyocytes by fatty tissue in the current case.