Abstract
Of the endomyocardial biopsy cases of clinically suspected dilated cardiomyopathy and non-specific myocarditis examined at Juntendo University Hospital and the Cardiovascular Institute Hospital, Tokyo, between 1979 and 1989, 49 cases of non-specific myocarditis (Myo), 54 of postmyocarditic cardiomegaly (PMC) and 14 of dilated cardiomyopathy (DCM) were selected from the following histological criteria : i. e. monocytic infiltration including lymphocytes for Myo ; myocardial fibrosis of replacement and/or interstitial type, proliferation of small vessels, myocyte-hypertrophy and disarrangementfor PMC ; and nonspecific myocyte-degeneration, hypertrophy and fibrosis for DCM.
The EKG features were as folloes : (1) Ventricular arrhythmias including ventricular tachycardia and specific negative T waves (prominent symmetrical negative T appeared in V5, sand/or aVF) were dominantly observed in Myo and PMC. (2) Biphasic P and negative T in VI were characteristic in Myo. (3) Supra-ventricular arrhythmias including atrial fibrillation (flutter) and Sick Sinus Syndrome, and right bundle branch block appeared in PMC with a higher incidence than in other groups. (4) Nonspecific ST-T change (sagging ST segment), left bundle branch block and left axis deviation of the QRS complexes were dominant in DCM.
Although the biopsy diagnosis of Myo and PMC were expected correct when the positive findings appeared under a microscope, the tendency of focal distribution of chronic inflammtory lesions increase the chance of the biotome escaping from an adequate samplig site. It would lead to erroneous diagnosis of some Myo and PMC cases as DCM. Nonetheless, the characterisitic EKG change in Myo, PMC and DCM could improve the differential diagnosis of these previously obscure categories of myocardial diseases.
