Vesicular myocardial change: an ultrastructural study of double membrane-bound vesicles in the human heart.

Vesicular myocardial change is a specific and common finding in the diseased hearts of humans and experimental animals. The small to large vesicles are generally bound by a double membrane. They are formed within myocardial cells and then possibly extruded into the extracellular space where they disintegrate or are phagocytosed by mononuclear cells. On the basis of our studies, most vesicles appear to be of mitochonrial origin. In humans, vesicular myocardial change appears to be most extreme in primary cardiomyopathy. It may also be present, but in lesser degree, in the apparently normal hearts of human adults. Vesicular myocardial change probably represents a specific mechanism by which myocardial cells eliminate damage mitochondria or other undesirable elements that build within them as a result of disease, aging, and perhaps normal physiological activity.