Capillarization of the hypertrophic heart: discrepancy of the results obtained by the triangulation and domain methods.

The geometry of capillary networks was examined in pressure-overloaded hypertrophic rat myocardium. All hearts were exposed to a staining protocol that distinguished the arteriolar (AC) and venular (VC) regions of capillaries. In control hearts, the triangulation method (one-dimensional distance between neighboring capillaries) and the domain method (two-dimensional area surrounding capillaries) exhibited similar results, showing increased capillarization for the venular region of capillaries networks. In hypertrophic hearts, the triangulation method did not demonstrate differences between arteriolar and venular capillaries (AC = 27.2 +/- 0.4 microns, VC = 27.0 +/- 0.2 microns, p = 0.56). However, the domain method still detected smaller tissue supply regions for venular capillaries (AC = 547 +/- 6 microns 2, VC = 464 +/- 5 microns 2, p less than 0.01). To resolve this discrepancy in hypertrophic heart, we have measured capillary spacing from longitudinal sections at discrete intervals along the A-V path length. These results indicate a stepwise decrease in intercapillary distance from arteriole to venule for both groups, which would support results obtained by the domain method. A possible explanation for the discrepancy between these two methods, specific to hypertrophic heart, may be changes in the clustering patterns of arteriolar and venular capillaries.