Left ventricular (LV) aneurysms represent a serious complication following a myocardial infarction (MI), particularly ST-elevation myocardial infarction (STEMI). While echocardiography (echo) remains the gold standard for diagnosis, the electrocardiogram (ECG) plays a crucial role in identifying potential aneurysms and monitoring their evolution. This article delves into the electrocardiographic manifestations of LV aneurysms, differentiating them from pseudoaneurysms, exploring the significance of ST-T wave changes, and highlighting the importance of the T/QRS ratio in specific leads. We will also touch upon surgical interventions and the specific characteristics of apical aneurysms.
Understanding the Pathophysiology of LV Aneurysms and Pseudoaneurysms:
A left ventricular aneurysm is a localized outpouching or bulging of the ventricular wall, resulting from myocardial necrosis and subsequent weakening of the cardiac muscle. This typically occurs following a large STEMI, where significant myocardial damage leads to impaired contractility and structural abnormalities. The aneurysm's formation is a consequence of the scar tissue replacing the infarcted myocardium, unable to withstand the normal pressures generated during ventricular contraction. This results in a dyskinetic or akinetic segment, characterized by paradoxical movement during systole.
A left ventricular pseudoaneurysm, on the other hand, is a different entity altogether. Unlike a true aneurysm, where the entire thickness of the ventricular wall is involved, a pseudoaneurysm involves a rupture of the ventricular wall, with the resulting hematoma contained only by the pericardium or surrounding tissues. The pseudoaneurysm's wall is composed of pericardium, thrombus, and surrounding fibrous tissue, not the intact myocardium. This distinction is crucial, as the management and prognosis differ significantly between true and pseudoaneurysms.
LV Pseudoaneurysm vs. True Aneurysm: A Comparative Analysis:
| Feature | LV True Aneurysm | LV Pseudoaneurysm |
|-----------------|-------------------------------------------------|------------------------------------------------|
| Wall Composition | Involves all layers of the ventricular wall; thinned myocardium | Composed of pericardium, thrombus, and fibrous tissue; no intact myocardium |
| Shape | Typically spherical or saccular | Often irregular and less well-defined |
| Risk of Rupture | Lower risk of rupture (unless very large) | Higher risk of rupture and tamponade |
| ECG Findings | Persistent ST-segment elevation, T-wave inversion | Variable ECG findings; may mimic true aneurysm or be less prominent |
| Echocardiography | Clear visualization of the aneurysm's size and shape | Visualization of the contained hematoma; often a thinner neck connecting to the ventricle |
| Treatment | Medical management, surgical repair (if symptomatic) | Usually requires surgical repair to prevent rupture |
ECG Changes in LV Aneurysm:
The ECG in patients with LV aneurysms often reveals characteristic changes, though these may not always be present or diagnostic on their own. The most common findings include:
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