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[Atrioventricular block and localized reentry into the trunk of the bundle of His]
Insights
This study identifies a complex atrioventricular block mechanism involving reentry within the His bundle. Findings reveal bidirectional block and echo reentry, explaining variable heart rhythms.
Area of Science:
- Electrophysiology
- Cardiology
- Cardiac Electrophysiology
Background:
- Atrioventricular (AV) block presents with variable rhythms, often necessitating detailed electrophysiological study.
- Dissociated P waves with coupled ventricular complexes suggest complex conduction abnormalities.
Observation:
- Intracavitary investigation was performed on a patient with AV block and variable rhythm.
- Standard ECG showed P waves dissociated from ventricular complexes.
Findings:
- Complete bidirectional AV block was identified in the upper His bundle, with a proximal His potential fixed to atrial activity.
- Distal His potentials indicated His bundle escape or early branch activation.
- Reentry echoes, associated with a distinct His bundle potential, were observed, elucidating the mechanism of variable rhythm.
Implications:
- Understanding these complex reentry mechanisms is crucial for diagnosing and managing challenging AV block cases.
- This detailed electrophysiological mapping provides insights into His bundle function and dysfunction.
- Findings may guide therapeutic strategies for patients with refractory arrhythmias due to His bundle reentry.
Abstract:
In a patient with an AV block and a resulting variable rhythm, the coupled ventricular complexes with dissociated P waves on the standard tracing suggested a reentry into the atrioventricular area. Intracavitary investigation revealed: 1) a complete bidirectional AV block in the upper portion of the bundle of His (there being a proximal His potential with a fixed relationship with the dissociated atrial activity shown on the ventriculogram); 2) escape of the bundle of His low down, or of the beginnings of the branches, preceded by a distal Hispotential; 3) re-entry echos preceded by a third variety of potential in the bundle of His.