Three-Dimensional Remodeling of Cardiomyocytes in a Patient With Aortic Stenosis
Scanning Electron Microscopy
A 77-year-old man was admitted to our hospital because of anterior chest pain. An echocardiogram demonstrated aortic valvular stenosis with calcification of the whole aortic root, concentric left ventricular hypertrophy, and slightly reduced left ventricular wall motion. Cardiac catheterization study showed a peak transaortic pressure gradient of 89 mm Hg and an aortic valve area of 0.52 cm2. We were planning surgical treatment, but the patient suddenly died because of syncope.
Scanning electron microscopy can be used to observe the 3-dimensional structures of a cell directly at high resolution. It is possible to use scanning electron microscopy to observe the features of cardiomyocyte surfaces after the removal of surrounding connective tissue,1 as well as the connective tissue skeleton after the removal of nonfibrous elements.2 In the present study, we used scanning electron microscopy to make these 2 types of observations on the same tissue specimens of human left ventricular myocardium from the patient described above, who had severe aortic stenosis. The myocardial tissue was obtained from the epicardial site of the left ventricular anterolateral wall. Control specimens were from the autopsied heart of a normal subject without cardiac disease.
Use of the first method showed that in addition to hypertrophy of cardiomyocytes, lateral branches were well developed between the cardiomyocytes, which resulted in a characteristic whorled pattern in which the cell-cell arrangement and myofibrillar architecture were disorganized (Figure 1). Use of the second method showed that interstitial connective tissue elements were clearly increased and thickened (Figure 2). The 3-dimensional remodeling of cardiomyocytes and the interstitial space described here may be an adaptive response to pressure overload3,4 and the cellular structural bases in left ventricular hypertrophy of the heart as a whole organ.
Okabe M, Kawamura K, Terasaki F, Hayashi T. Remodeling of cardiomyocytes and their branches in juvenile, adult, and senescent spontaneously hypertensive rats and Wistar Kyoto rats: comparative morphometric analyses by scanning electron microscopy. Heart Vessels. 1999; 14: 15–28.
Krayenbuehl HP, Hess OM, Monrad ES, Schneider J, Mall G, Turina M. Left ventricular myocardial structure in aortic valve disease before, intermediate, and later after aortic valve replacement. Circulation. 1989; 79: 744–755.