The cardiac interstitium is a diverse system of extracellular-matrix (ECM) components organized into a stress tolerant three-dimensional network that interconnects the cellular components of the heart. During each contraction of the heart, a complex set of mechanical forces is transmitted through the cardiac interstitium and is applied to the cardiac myocytes and fibroblasts. In comparison to the relaxed heart, each contractile wave results in a rapid reorganization of the extracellular matrix and cell cytoskeleton. A number of studies have shown that by varying the normal pattern of applied mechanical force that occurs during heart contraction, both the phenotype and function of myocytes and fibroblasts in the heart may be altered.

At the molecular level components of the ECM are attached to the cardiac myocytes and fibroblasts via specific transmembrane integrin receptors. Each integrin is comprised of an extracellular domain that attaches to an ECM component, and an intracellular domain that attaches to a cytoplasmic component of the cell.