Abstract
Intact retrograde ventriculoatrial (VA) conduction in the presence of complete atrioventricular (AV) heart block has been well-documented in the past. We sought to describe the prevalence and clinical significance of intact VA conduction accompanied by complete antegrade AV block in patients with implanted cardiac rhythm management (CRM) devices. During routine follow-up of CRM devices in our device clinic, 42 patients were found to be in a state of complete heart block. All patients presented in sinus rhythm. The patients’ underlying rhythms were tested with the inhibition of pacing and documented AV dissociation. Subsequently, retrograde VA conduction was tested with ventricular pacing. In the 42 patients with complete heart block as the underlying rhythm, five patients demonstrated retrograde VA conduction. In conclusion, the prevalence of intact of VA conduction was 11.9% in our study. The implications of this phenomenon can have noteworthy clinical significance. The occurrence of pacemaker-mediated tachycardia and repetitive nonreentrant VA synchrony are discussed herein. All patients, even those with a device indication of complete heart block, should be tested for retrograde conduction at implantation and during routine follow-up.
Highlights
In patients with complete atrioventricular (AV) block, the presence of intact retrograde ventriculoatrial (VA) conduction has been well-documented in the past.[1,2]
Within a device clinic population of more than 1,100 patients, 42 patients were found to be in complete AV block during a routine evaluation of their cardiac rhythm management (CRM) device between September 2012 and April 2013
Of the 42 patients who presented in complete AV block as the underlying rhythm, five patients (11.9%) demonstrated intact retrograde VA conduction
Summary
In patients with complete atrioventricular (AV) block, the presence of intact retrograde ventriculoatrial (VA) conduction has been well-documented in the past.[1,2] In a large study of 432 patients with complete AV block, 14% of the study population demonstrated intact VA conduction.[3] Other studies show a prevalence of about 15%.4,5. The implications have more clinical importance given the high volume of cardiac device implantations, especially with the use of dual-chamber pacing.[6]. Clinical research supports the hypothesis of the existence of bidirectional pathways, one for antegrade conduction and one for retrograde conduction.[7,8,9,10] the local conduction disease of one pathway can lead to unidirectional block, allowing for conduction to be present in the opposite direction.[11,12]
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