Isolated left posterior fascicular block associated with acquired ventricular septal defect
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Isolated left posterior fascicular block is rare, but can indicate septal rupture after myocardial infarction. This finding in patients may alert clinicians to this serious complication.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Anatomy
Background:
- Isolated left posterior fascicular block is a rare electrocardiographic finding.
- The posterior fascicle of the left bundle branch is anatomically protected and has a dual blood supply, making it less prone to injury.
- Previous studies have shown mechanical disruption can cause this block in animal models, but not in humans.
Observation:
- Two cases of inferior wall myocardial infarction are presented.
- Both cases were complicated by rupture of the inferior septum.
- This rupture resulted in the development of isolated left posterior fascicular block.
Findings:
- The study demonstrates that isolated left posterior fascicular block can occur in humans following myocardial infarction.
- Septal rupture following inferior wall myocardial infarction is identified as a cause of this specific electrocardiographic finding.
- This association has not been previously documented in human cases.
Implications:
- The development of isolated left posterior fascicular block during myocardial infarction may serve as a critical alert for underlying septal rupture.
- Early recognition of this sign can prompt timely diagnostic evaluation and intervention for septal rupture.
- This finding enhances the diagnostic utility of electrocardiography in identifying life-threatening mechanical complications of myocardial infarction.
Abstract:
Isolated left posterior fascicular block in the absence of associated right bundle-branch block is a rare electrocardiographic finding. In view of its anatomy and the fact that it receives a dual blood supply, the posterior fascicle of the left bundle branch appears to be less vulnerable than the anterior fascicle or the right bundle. Mechanical disruption of the posterior fascicle can produce isolated left posterior fascicular block. This has been demonstrated in animal models. However, such occurrence has not been noted in humans. We present two cases of inferior wall myocardial infarction, complicated by rupture of the inferior septum, resulting in isolated left posterior fascicular block. The development of isolated left posterior fascicular block complicating myocardial infarction may, therefore, serve to alert to the possible underlying septal rupture.