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Challenges in Clinical Electrocardiography |

Atrioventricular Block With 2:1 Conduction—Discussion

JAMA Intern Med. 2013;173(5):336-337. doi:10.1001/jamainternmed.2013.3182b.
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Correspondence: Adam Elkin, MD, Kanbar Cardiac Center, 2333 Buchanan St, Office 1-111, San Francisco, CA 94115 (adelkin2001@yahoo.com).

Published Online: February 11, 2013. doi:10.1001/jamainternmed.2013.3182

Conflict of Interest Disclosures: None reported.

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Figure 2. Telemetry tracing before and after Valsalva maneuver. Initially, there is a 2:1 atrioventricular (AV) block with slightly irregular P-P intervals, consistent with sinus arrhythmia. With increased vagal tone, the sinus rate (P-P interval) and AV nodal conduction (P-R interval) slow, allowing brief 1:1 AV nodel conduction and providing further evidence of an infranodal block. The final QRS complex does not represent a junctional escape beat because it occurs early relative to the preceding R-R intervals, indicating anterograde conduction.




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