[Submicroscopic indication of pathological cell growth in hypertrophic cardiomyopathy (HCM) in humans].

The increasing application of transvascular endomyocardial biopsy for diagnostic verification of various heart diseases and elucidation of their etiology relies mainly on light microscopical methods. It is shown by hypertrophic cardiomyopathy as an example that also submicroscopical findings may be of value in diagnostic work, prognosis, and investigating research for etiological relationships. Specific morphological markers for idiopathic HCM were not demonstrable; nevertheless, some characteristic alterations such as fibrillary disorder, excessive folding of nuclear-, intercalated disc-, and sarcolemmal membranes, contraction bands, accumulation of mitochondria, glycogen, and lipid droplets, among others as well as sometimes the thickening of vascular walls with its unknown relations to the so-called "small vessel disease" may be helpful when endomyocardial biopsies are examined with the electron microscope too. Though many cytomorphologic findings are similar to those in dilatative cardiomyopathy, this disease probably is not a final state of HCM. In order to prove the actual cause of both heart failures, more intensive investigating research especially at the molecular biological level is required.