Key result
His bundle electrogram confirmed the fascicular origin of narrow QRS (100 ms) premature beats with coupling intervals of 560-600 ms in a patient with bundle-branch block.
Why the study?
What is the electrophysiologic mechanism of fascicular premature beats with narrow QRS in the presence of bundle-branch block?
Case Report (n=1)
What is the electrophysiologic mechanism of fascicular premature beats with narrow QRS in the presence of bundle-branch block?
This case report suggests a new electrophysiologic mechanism for fascicular premature beats presenting with a narrow QRS complex in the setting of bundle-branch block.
May refine EP diagnosis of narrow QRS ectopy in bundle-branch block; single case leaves prevalence open.
The electrocardiogram of a sixty-two-year-old male revealed right bundle-branch block, left anterior superior fascicular block, and right precordial Q waves consistent with anteroseptal myocardial infarction. Premature beats with narrow QRS (100 ms) occurred intermittently; coupling intervals varied between 560-600 ms. His bundle electrogram confirmed the fascicular origin of the premature beats. During atrial prematuring studies, it was shown that an appropriately timed premature beat could prolong infra-His conduction time, but QRS normalization was not achieved. The possible electrophysiologic mechanisms that could result in a normal QRS complex with fascicular premature beats in this patient are discussed; a new mechanism is suggested.
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Venkataraman et al. (1980) conducted a case report in Fascicular premature beats with narrow QRS in the presence of bundle-branch block (n=1). His bundle electrogram and atrial prematuring studies was evaluated on Electrophysiologic mechanism of premature beats. His bundle electrogram confirmed the fascicular origin of narrow QRS (100 ms) premature beats with coupling intervals of 560-600 ms in a patient with bundle-branch block.
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