What is the Origin of Myocardial Stretch?

The term combines "Myocardial," referring to the heart muscle, with "Stretch," denoting the physical deformation. The physiological concept is fundamentally linked to the Frank-Starling law of the heart, which describes the relationship between end-diastolic volume and stroke volume. Modern endocrinology incorporated this term to explain the mechanical stimulus for natriuretic peptide release, redefining the heart's role as a mechano-endocrine organ.

What is the Mechanism of Myocardial Stretch?

Acutely, the stretch optimizes the overlap between actin and myosin filaments within the sarcomere, enhancing contractile efficiency. Chronically, however, excessive stretch activates mechanoreceptors and triggers a complex neurohormonal cascade, including the release of Brain Natriuretic Peptide (BNP) from the endocrine heart. This sustained mechanical stimulus ultimately leads to maladaptive cardiac remodeling, hypertrophy, and fibrosis, compromising long-term heart function.

Myocardial Stretch ∞ Area

Myocardial Stretch

Meaning

Myocardial stretch refers to the physical distension or elongation of the cardiac muscle fibers (cardiomyocytes) within the walls of the heart chambers, primarily in response to increased blood volume or pressure loading. This mechanical stress is a critical physiological stimulus that triggers the heart’s intrinsic Frank-Starling mechanism, governing the force of contraction. However, chronic, excessive stretch is a key pathological signal in the progression of heart failure and a major stimulus for hormonal release.