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Gap phenomenon in "the right and left bundle branch systems" during retrograde conduction in man
Insights
The V3 phenomenon in bundle branch reentrant circuits involves a gap in retrograde conduction. This gap, observed in two patients, affects the His-Purkinje system during reentry.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Anatomy
Background:
- Reentry within the His-Purkinje system can cause complex arrhythmias.
- The V3 phenomenon is a specific manifestation of retrograde conduction block.
- Understanding bundle branch conduction is crucial for diagnosing cardiac arrhythmias.
Observation:
- Two patients exhibited the V3 phenomenon, characterized by a gap in retrograde conduction through the bundle branches.
- Premature impulses (S2) showed variable block and conduction pathways (right vs. left bundle branch) depending on coupling intervals.
- Sudden prolongation of the S2H2 interval and the appearance of V3 correlated with specific conduction patterns.
Findings:
- The study details a novel gap phenomenon during retrograde His-Purkinje system conduction, termed the V3 phenomenon.
- This phenomenon involves dynamic changes in conduction block and recovery within the right and left bundle branches.
- The observed patterns suggest a mechanism similar to antegrade bundle branch conduction gaps, involving proximal delay and distal recovery.
Implications:
- This research enhances the understanding of complex electrophysiological mechanisms in cardiac arrhythmias.
- Identifying the V3 phenomenon can refine diagnostic approaches for His-Purkinje system reentry.
- Further investigation into these gap phenomena may reveal new therapeutic targets for managing ventricular arrhythmias.
Abstract:
Gap phenomenon in right and left bundle branch systems during retrograde conduction is described in two patients with manifest reentry within the His-Purkinje System (V3 phenomenon). In this form of gap the premature impulse (S2) initially blocked in the right bundle branch system and conducted retrogradely via the left bundle branch system as manifested by sudden prolongation of S2H2 interval and appearance of V3. At close coupling intervals S2 impulse encountered retrograde block in the left bundle branch system and resumed retrograde conduction via the right bundle branch system with S2H2 intervals shorter than critical value and was not followed by V3. However, on further shortening the S1S2 intervals S2 impulse blocked again in right bundle branch system and resumed conduction via the left bundle branch system with S2H2 intervals longer than critical values and V3 reappeared. The mechanism of these gaps is not clear but we believe is similar to the one proposed in Types I and II gaps in antegrade bundle branch conduction and involves proximal delay allowing distal recovery. The similarities and differences between the gap phenomenon in bundle branches during antegrade and retrograde conduction are discussed.