Do endomyocardial biopsies represent the morphology of the rest of the myocardium?

In this paper some possibilities have been explored for the contradictory reported results correlating morphological findings on tissue obtained by bioptome to haemodynamic and other clinical parameters. To illustrate the problem endomyocardial biopsies obtained from 79 patients, either from the right or left ventricle, have been analysed quantitatively. Emphasis was placed on the size of the biopsy, cell diameter and volume fraction of collagen as well as volume fraction of interstitium. The results have shown that great variability exists when comparing two biopsies from the same ventricle. The coefficient of variance regarding fibre diameter and volume fraction of interstitium was 18.6 and 28.9%, respectively, and amounts to 80.5% for the volume fraction of collagen. In addition, investigations as to whether or not the small tissue samples obtained by bioptome are representative of the rest of the myocardium, have been undertaken. For this purpose 23 hearts obtained at post-mortem have been analysed quantitatively, measuring the volume fraction of collagen. The results have shown that when five or more tissue samples have been obtained, quantitative representation of the interventricular septum (the rest of the myocardium?) is mirrored in the small tissue samples. It is, therefore, concluded that at least five biopsies are necessary to establish whether or not correlation between structural changes and the functional state of the heart exists. Unless this number of biopsies has been obtained, extreme caution in assessing prognosis must be exercised.