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[Occult ventricular bigeminy. Description of a case with extrasystole variable coupling separated by sinus beats in
Insights
This study identifies an atypical form of concealed ventricular bigeminy by analyzing electrocardiogram patterns. The findings reveal a unique relationship between coupling intervals and preceding sinus beats, aiding in diagnosis.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Ventricular extrasystoles are common cardiac arrhythmias.
- Ventricular bigeminy involves frequent premature ventricular contractions.
- Concealed bigeminy is characterized by irregular patterns of sinus beats between extrasystoles.
Observation:
- Analysis of electrocardiograms revealed unifocal ventricular extrasystoles with variable coupling intervals.
- Ventricular bigeminy was observed, often with multiple sinus beats between extrasystoles.
- A distinct pattern emerged where coupling intervals varied based on the number of preceding sinus beats (odd or even).
Findings:
- An atypical form of concealed ventricular bigeminy was identified.
- This arrhythmia involves a ventricular ectopic focus with proximal 2:1 block and distal irregular block.
- The number of intervening sinus beats (odd or even) consistently correlated with coupling interval length, distinguishing it from typical concealed bigeminy.
Implications:
- This discovery aids in recognizing a previously uncharacterized ventricular arrhythmia.
- Understanding this pattern can improve diagnostic accuracy for complex ventricular arrhythmias.
- Further research into the electrophysiological mechanisms of concealed bigeminy is warranted.
Abstract:
We have analyzed an electrocardiogram showing many unifocal ventricular extrasystoles with wide variations of the coupling intervals. Ventricular bigeminy was frequent but in many instances more than one sinus beat occurred between two consecutive extrasystoles. In such a case the intervening sinus beats occurred indifferently both in odd and even numbers. Moreover, extrasystoles preceded by an even number of sinus beats had a relatively long coupling interval whereas extrasystoles that followed and odd number of sinus beats showed shorter coupling intervals. An opposite pattern of the coupling interval was observed with the extrasystoles that followed an interpolated premature ventricular depolarization. In such a case the coupling interval was long after an odd number of sinus beats and vice versa. This mechanism may be interpreted as due to concealed ventricular bigeminy caused by a ventricular ectopic focus which is surrounded by two different zones of block: a proximal zone of 2:1 block, and a distal one in which the block occurs irregularly. Unlike what appears in typical concealed bigeminy, characterized by only odd numbers of sinus beats between consecutive extrasystoles the intervening sinus complexes are indifferently in odd and even numbers. The constant relationship between the coupling interval and the number (odd or even) of sinus beats by which the extrasystole is preceded, allows us to recognize the presence of an atypical form of concealed bigeminy.