Related Experiment Videos
An unusual PR interval alternans during 2:1 atrio-ventricular block.
Pacing and Clinical Electrophysiology : PACE
|March 1, 1983
Summary
This study examines 2:1 second-degree atrioventricular (AV) block, revealing alternating PR intervals not due to concealed or supernormal conduction. The findings suggest a pathophysiological basis involving alternate pathways in the AV junction.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Electrophysiology
Background:
- Second-degree atrioventricular (AV) block is characterized by intermittent failure of atrial impulses to conduct to the ventricles.
- A 2:1 AV block pattern signifies that for every two P waves, only one is followed by a QRS complex.
- PR interval alternations in AV block can be complex and require careful electrophysiological analysis.
Observation:
- A specific case of 2:1 second-degree AV block during sinus rhythm presented with alternating PR interval durations.
- These PR interval variations occurred either separately or alternated beat-by-beat.
- The observed PR interval alternans were not attributable to concealed conduction from preceding blocked impulses or supernormal conduction.
Findings:
- The study identified a primary PR interval alternans in 2:1 AV block.
- This phenomenon was explained by the alternating conduction of impulses through faster and slower pathways within the atrioventricular junction.
- The findings differentiate this mechanism from previously proposed explanations involving concealed or supernormal conduction.
Implications:
- Understanding the mechanism of PR interval alternans in 2:1 AV block can refine diagnostic criteria.
- This insight contributes to a deeper understanding of atrioventricular nodal physiology and conduction abnormalities.
- Further research may explore the clinical significance and management strategies for patients exhibiting this specific electrophysiological pattern.