Cardiac Hypertrophy

Increased bulk of myocardium due to increased cell size. Estimated most accurately by chamber wall thickness.

Right sided hypertrophy results in increased heart width.

Left sided hypertrophy results in increased heart length.

Bilateral hypertrophy results in a round heart shape.

• Physiological: In resposnse to exercise in athletic animals E.g. racing greyhounds.
• Pathological:
  • Concentric: Due to pressure overload E.g. restrictive pericarditis. Thickened chamber walls with a decreased chamber lumen, often will result in myocardial hypoxia. Fibrosis of the myocardium will restrict chamber expansion and filling at diastole leading to diastolic failure.
  • Eccentric: Due to volume overload. Increased wall thickness, which may be variable, with a dilated chamber. E.g. mitral regurgitation will result in eccentric hypertrophy of the left atrium.

When the disease progress occurs too rapidly to allow the heart to adapt dilation will occur. Dilation is also seen at the onset of decompensation of a previously compensating failing heart.