Cardiac Hypertrophy & Dilation
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Cardiac Hypertrophy:
Pressure-overload hypertrophy:
Characterized by thickened myocardium*:
Increased pressure work raises myocardial oxygen consumption, and, in response to increased demand, the myocardial wall thickens concentrically.
- Thickness increases as new sarcomeres are produced in parallel to existing cells.
Volume-overload hypertrophy:
- Chambers adapt to increased volume by dilating to mitigating pressure by increasing compliance.
- Dilation can lead to thinner, thicker, or normal myocardial wall; increased heart weight is better indicator of dilation than is wall thickness.
- Sarcomeres are added within existing cells.
Addition of fibrous tissue
- Prolonged overload leads to fibrous tissue deposits.
Cardiac blood supply
- Hypertrophy increases oxygen and nutrient demands of the myocardial tissue, but IS NOT accompanied by proportional addition of new capillaries; thus, blood supply in the hypertrophied heart is compromised.
- Can lead to cardiac failure.
Non-pathologic/Physiologic Hypertrophy
- Long-term strenuous aerobic activity can also cause volume-load hypertrophy.
- Capillary density may increase, unlike in pathologic hypertrophy, meeting demands of cardiac work.