Left ventricular aneurysm pathophysiology

Aneurysms form when the intraventricular tension stretches the non contracting, infarcted heart muscle, resulting in an expansion of the thin layer of necrotic muscle and fibrous tissue, which bulges with each cardiac contraction. The wall of a mature aneurysm is a white fibrous scar. It becomes more densely fibrotic as the time passes, and bulges outward with each cardiac contraction, resulting in a reduction of the left ventricular stroke volume. On microscopy, hyalinized fibrous tissue is the predominant finding. It usually takes 1 month for fibrous tissue to form.

• Hyalinized fibrous tissue is the predominant finding.
  • However, a small number of viable muscle cells are also usually present.^[1]
• It usually takes 1 month for fibrous tissue to form.
  • Collagen tissue is formed during the first 10 days.
  • When an aneurysm is present within 1 week of a first myocardial infarction, the wall is composed largely of necrotic muscle and it is therefore not a true aneurysm by definition.^[2]

• The wall of a mature aneurysm is a white fibrous scar.
  • The aneurysmal portion of the LV wall is thin. A mural thrombosis (which can be calcified), may be seen attached to the endocardial surface.^[3]
  • The endocardium beneath retains its trabeculations; the area of scarring is not clearly demarcated from the rest of the wall.
• The wall of the aneurysm becomes more densely fibrotic as the time passes, it bulges outward with each cardiac contraction and compromises the left ventricular stroke volume.

The gross pathologic features of LV aneurysm are shown below.^[4]

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