Relation of regional cross-fiber shortening to wall thickening in the intact heart. Three-dimensional strain analysis by NMR tagging.

Abstract

Cross-fiber shortening at the endocardium, therefore, far exceeds cross-fiber shortening at the epicardium and fiber shortening at both epicardium and endocardium. Since no active shortening can occur locally in the cross-fiber direction, the extensive endocardial cross-fiber shortening must result from interaction with differently aligned fibers at a distance. The correlation between regional thickening and cross-fiber shortening supports the hypothesis that this interaction is the mechanism for amplifying small amounts of fiber shortening to cause extensive endocardial thickening.