Josephson Clinical Cardiac Electrophysiology

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Chapter 5: Miscellaneous Phenomena Related to Atrioventricular Conduction ■

fb

1

1

aVF

aVF

V1

V1

A

A

A V

V

A

V

V

V

H

H

HBE

HBE

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V

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V

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RVA

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FIGURE 5.3 Retrograde concealed conduction during ventricular tachycardia. The tracing is arranged from top to bottom: surface electrocardio gram (ECG) leads 1, aVF, and V1; His bundle electrogram (HBE); right ventricular apex (RVA); left ventricular apex (LVA); and time lines (T) at 10 and 100 msec. The left panel represents sinus rhythm. The right panel represents ventricular tachycardia without manifest retrograde conduction. Retrograde His bundle or atrial deflections are not seen. There are three sinus complexes, as reflected by atrial deflections (A) in the HBE trac ing. Only the second results in a propagated response with a His bundle deflection (H) and a slight alteration in the QRS complex characteristic of a fusion beat (fb). Block of the first and third sinus impulses in the atrioventricular (A-V) node and prolongation of the A-H interval during the conducted second sinus beat result from retrograde concealed conduction of the ventricular beats into the A-V node.

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aVF

V1

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A H

A H

H A A

330

HBE

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HRA LRA

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aVF

V1

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A H V

330 V

HBE

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A

HRA LRA

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A

T

B

Copyright © 2023 Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. FIGURE 5.4 Concealed conduction by ventricular premature complexes (VPCs). A and B. Leads 1, aVF, and V1 and electrograms from the His bundle (HBE), high right atrium (HRA), and low right atrium (LRA). Sinus rhythm is present in the first two complexes of each panel. A. A VPC is observed at a coupling interval of 330 msec with retrograde conduction through the His bundle to the atrioventricular (A-V) node. This results in concealed conduction so that the subsequent sinus complex blocks in the A-V node. B. A similarly coupled VPD fails to reach the His bundle so that no concealment in the A-V node is manifested and the sinus complex conducts with a normal H-V and normal A-H. Thus, the ability to produce concealed conduction in the A-V node by VPC depends on the ability to penetrate the A-V node via the His-Purkinje system. T, time line.