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Re-entry due to manifest and concealed. His bundle ectopic systoles. Report of a case
Insights
Concealed His bundle ectopic systoles can cause atrioventricular block and mimic nonconducted atrial beats. These events can initiate re-entrant arrhythmias through retrograde conduction, impacting cardiac electrophysiology.
Area of Science:
- Electrophysiology
- Cardiology
Background:
- His bundle ectopic systoles (H') are known to cause atrioventricular (A-V) block and simulate nonconducted atrial premature beats (P').
- A 69-year-old male with arteriosclerotic heart disease presented with Wenckebach type second-degree A-V block within the His-Purkinje system.
Observation:
- His bundle studies revealed H' conducting to both atria and ventricles, or only to the atria, mimicking nonconducted P' or atrial fusion beats.
- Late coupled H' (CH') that failed ventricular and atrial activation due to sinus capture were observed.
Findings:
- Both types of H' were capable of initiating re-entrant arrhythmias via retrograde conduction.
- CH' initiated re-entry by retrogradely conducting into a subatrial re-entry circuit.
- Evidence suggests re-entry involves a retrograde concealed accessory pathway and antegrade atrioventricular nodal conduction.
Implications:
- This study describes a previously unrecognized electrophysiologic consequence of concealed His bundle ectopy.
- Understanding these mechanisms is crucial for diagnosing and managing complex arrhythmias.
- The findings contribute to the understanding of re-entrant circuit formation in cardiac conditions.
Abstract:
Concealed (C) His bundle ectopic systoles (H') have been shown in man to give rise to first and second degree atrioventricular (A-V) block and to simulate nonconducted atrial premature beats (P'). This report outlines a hitherto undescribed electrophysiologic consequence of H' in a 69-year-old man with arteriosclerotic heart disease and a Wenckebach type second degree A-V block in the His-Purkinje system. During a His bundle study, H' were shown to conduct either to the atria and ventricles with varying relationships to P' and QRS, or to conduct only to the atria, simulating nonconducted P' or atrial fusion beats. Both types of H' could initiate a re-entrant arrhythmia during retrograde conduction. Of particular interest are late coupled H' that failed to conduct to the ventricles and also failed to activate the atria because of prior capture by the sinus impulse (CH'). These CH' could also initiate re-entry by conducting retrogradely to engage the subatrial re-entry circuit. Evidence is presented to suggest re-entry occurs by way of a retrograde concealed accessory pathway and antegrade conduction in the atrioventricular node.
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