Aneurysm, ventricular
LIFE-THREATENING DISORDERVentricular aneurysm is marked by an outpouching (almost always of the left ventricle) that produces ventricular wall dysfunction in 10% to 20% of patients after a myocardial infarction (MI). A ventricular aneurysm may develop within weeks after an MI, usually following anterior P-wave infarctions.
An untreated ventricular aneurysm can lead to arrhythmias, systemic embolization, or heart failure and may cause sudden death. Resection improves the prognosis in patients with heart failure or refractory ventricular arrhythmias.
Causes
When MI destroys a large muscular section of the left ventricle, necrosis reduces the ventricular wall to a thin sheath of fibrous tissue. Under intracardiac pressure, this thin layer stretches and forms a separate noncontractile sac (aneurysm).
Abnormal muscle wall movement
Accompanying ventricular aneurysm, abnormal muscle wall movement includes akinesia (lack of movement), dyskinesia (paradoxical movement), asynergia (decreased and inadequate movement), and asynchrony (uncoordinated movement).
During systolic ejection, the abnormal muscle wall movements associated with the aneurysm cause the remaining normally functioning myocardial fibers to increase the force of contraction in order to maintain stroke volume and cardiac output. At the same time, a portion of the stroke volume is lost to passive distention of the noncontractile sac.
Signs and symptoms
A ventricular aneurysm may cause arrhythmias (such as premature ventricular contractions and ventricular tachycardia), palpitations, signs and symptoms of cardiac dysfunction (weakness on exertion, fatigue, angina) and, occasionally, a visible or palpable systolic precordial bulge.
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