Myocyte cell death and ventricular remodeling.

The recognition that cell death in the myocardium is not only necrotic in nature but is also mediated by activation of the suicide program of myocytes has raised several questions concerning the magnitude of this phenomenon, and whether these two distinct forms of cell death are disease-dependent or coexist in the pathologic heart. Additionally, the times required for the completion of apoptotic and necrotic myocyte cell death are unknown, making the analysis of their respective rates in the myocardium impossible at present. The documentation that mechanical forces in vitro, mimicking diastolic Laplace overloading in vivo, can transmit a death signal to myocytes suggests that programmed cell death may be triggered in the stressed myocardium independently from the etiology of the overload. Because increasing pressure or volume loads, or both, in the failing heart induce myocyte hypertrophy and proliferation, a challenging question is whether the induction of genes regulating these cellular growth processes may activate programmed cell death as well. Finally, the identification of the mechanisms responsible for the translation of a diffuse environmental condition into a death signal in a limited number of cells scattered across the ventricular wall is a major challenge of future research.