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The ECG Blog with Reid

Inferoposterior STEMIs and Complete Heart Block: A Look at AV Node Anatomy and RCA Supply Jun 04, 2025

Complete heart block—or third-degree AV block—is a feared complication of ST segment elevation myocardial infarction (STEMI), particularly when the infarct involves the inferior or posterior walls of the heart. This pattern is not random. It’s grounded in the anatomical relationship between the righ...

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Why Atrial Fibrillation with Ventricular Pacing Can Appear Regular Jun 02, 2025

Atrial fibrillation (AF) is classically described as an irregularly irregular rhythm, defined by chaotic atrial activity and a ventricular response that lacks any predictable pattern. However, a unique exception occurs in patients who have ventricular pacing, especially those with complete AV block ...

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Atrial Fibrillation with Complete Heart Block: The Physiology of “Regularized” Atrial Fibrillation Jan 24, 2025

Atrial fibrillation (AF) is classically characterized by an irregularly irregular ventricular rhythm due to chaotic atrial depolarization and random conduction through the atrioventricular (AV) node. However, in rare instances, AF can produce a regular ventricular rhythm—a phenomenon that occurs whe...

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