Three-Dimensional Architecture of Cardiomyocytes and Connective Tissues in Hypertrophic Cardiomyopathy

Abstract

HomeCirculationVol. 125, No. 5Three-Dimensional Architecture of Cardiomyocytes and Connective Tissues in Hypertrophic Cardiomyopathy Free AccessBrief ReportPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessBrief ReportPDF/EPUBThree-Dimensional Architecture of Cardiomyocytes and Connective Tissues in Hypertrophic CardiomyopathyA Scanning Electron Microscopic Observation Yumiko Kanzaki, MD, Yohei Yamauchi, MD, Makoto Okabe, MD, Fumio Terasaki, MD and Nobukazu Ishizaka, MD Yumiko KanzakiYumiko Kanzaki From the Department of Cardiology, Osaka Medical College, Osaka, Japan. *Drs Kanzaki and Yamauchi contributed equally to this work. Search for more papers by this author , Yohei YamauchiYohei Yamauchi From the Department of Cardiology, Osaka Medical College, Osaka, Japan. *Drs Kanzaki and Yamauchi contributed equally to this work. Search for more papers by this author , Makoto OkabeMakoto Okabe From the Department of Cardiology, Osaka Medical College, Osaka, Japan. Search for more papers by this author , Fumio TerasakiFumio Terasaki From the Department of Cardiology, Osaka Medical College, Osaka, Japan. Search for more papers by this author and Nobukazu IshizakaNobukazu Ishizaka From the Department of Cardiology, Osaka Medical College, Osaka, Japan. Search for more papers by this author Originally published7 Feb 2012https://doi.org/10.1161/CIRCULATIONAHA.111.054668Circulation. 2012;125:738–739Scanning electron microscopy is a useful modality to visualize the 3-dimensional structures of tissues at high resolution. In addition, processing the tissue samples can provide further architectural information: The removal of connective tissue around the cardiomyocytes and, conversely, the removal of nonfibrous tissue enable us to clearly observe the cardiomyocytes and connective tissue, respectively. Furthermore, backscattered electron emission after heavy-metal staining can provide higher-quality images of the intracellular architecture.1 We have previously reported the 3-dimensional structure of the human left ventricular myocardium.2 Here, we performed an electron microscopic examination of a myectomy specimen from a patient with hypertrophic cardiomyopathy using a Hitachi S-800 scanning electron microscope (Hitachi, Ltd, Tokyo, Japan). In this patient, asymmetrical hypertrophy of the left ventricular wall (interventricular septum, 19 mm; anterolateral wall, 14 mm) and a pressure gradient (85 mm Hg) at the site of left ventricle outflow were demonstrated by ultrasonography.Compared with a normal heart sample (Figure 1A), disarrayed, overlapping, and abnormally branched cardiomyocytes were observed in the hypertrophic cardiomyopathy heart sample after the removal of connective tissue (Figure 1B and 1C), although the proportion of myocardial disarray seemed to be much greater than in previous studies.3,4 Removal of the nonfibrous segments enabled us to observe thickened interstitial connective tissue, termed plexiform fibrosis (Figure 1E), which is characteristic of, but not specific to, patients with hypertrophic cardiomyopathy.Download figureDownload PowerPointFigure 1. Scanning electron microscopy of cardiomyocytes. Tissue samples from a normal subject (A, D) and a patient with hypertrophic cardiomyopathy (B, C, E, F) are shown. Images were obtained after the removal of either connective tissue (A, B, C) or nonfibrous tissue (D, E, F). In the heart sample from the patient with hypertrophic cardiomyopathy, myocardial disarray, abnormal branching, and bizarre myocardial hypertrophy (B, C) increased interstitial connective tissue elements (E) and thickened small intramural vessels, in which luminal narrowing (F) can be observed. Magnifications are ×600 (A, B, F), ×1000 (C), and ×300 (D, E). Bar indicates 20 μm.The backscattered electron image revealed further information at the levels of myofibril orientation and intercalated discs (Figure 2A). At higher magnifications, the A bands and the I bands were identified as broad bright zones and as dark zones, respectively (Figure 2B and 2C). In a normal heart sample, myofibrils are arranged longitudinally in a regular and parallel pattern. By contrast, disarrayed myofibrils and sarcomeres were also observed in our patient (Figure 2B and 2C).Download figureDownload PowerPointFigure 2. Backscattered electron image of a heart sample from a patient with hypertrophic cardiomyopathy. A, Lower-magnification image of cardiomyocytes and myocardial fibers. B and C, The higher-magnification image shows A bands as bright zones and I bands as dark zones. Myofibrillar disarray (arrows) and sarcomere disarray (arrowheads) can be observed. Magnifications are ×300 (A), ×1000 (B), and ×1500 (C). Bar indicates 20 μm.DisclosuresNone.Footnotes*Drs Kanzaki and Yamauchi contributed equally to this work.Correspondence to Yumiko Kanzaki, MD, Department of Cardiology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka 569-8686, Japan. E-mail [email protected]osaka-med.ac.jp