His bundle electrograms in four patients with accelerated idioventricular rhythms verified the idioventricular nature of the ectopic rhythm and localized the pacemaker site below the bundle of His.
Observational (n=4)
His bundle electrograms confirm the ventricular origin of accelerated idioventricular rhythms and demonstrate their suppression by increasing atrial rates.
Accelerated idioventricular rhythms (AIVR) are ectopic ventricular rhythms with rates intermediate between idioventricular escape rhythms (30 to 40/min) and ventricular tachycardia (120 to 180/min). Differentiation of AIVR from supraventricular arrhythmias rests primarily on demonstration of their ventricular origin. His bundle electrograms (HBE) were recorded in four patients during AIVR. HBE verified the idioventricular nature of the ectopic rhythm and excluded supraventricular rhythm with aberration as a cause. In addition, they permitted the recognition of normally conducted sinus beats, fusion beats, and idioventricular beats. The pacemaker site for the AIVR was below the bundle of His. AIVR became manifest when the heart rate was slowed by increasing vagal tone, premature atrial stimulation, and high degree atrioventricular (A-V) block. AIVR could be suppressed and 1:1 A-V conduction established by increasing the atrial rate with atropine or by atrial pacing.
Gallagher et al. (Fri,) conducted a observational in Accelerated idioventricular rhythms (AIVR) (n=4). His bundle electrograms (HBE) was evaluated on Verification of the idioventricular nature of the ectopic rhythm. His bundle electrograms in four patients with accelerated idioventricular rhythms verified the idioventricular nature of the ectopic rhythm and localized the pacemaker site below the bundle of His.