Paroxysmal atrioventricular block precipitated by an atrial premature beat. What is the mechanism?

Barold, S. Serge; Stroobandt, Roland X.

doi:10.5603/cj.2012.0123

Cited by 3 publications

(5 citation statements)

References 5 publications

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“…This form of AVB can be precipitated by PAC or ventricular premature beats, His bundle extrasystoles, or sinus rhythm slowing either spontaneously or induced by carotid sinus massage [ 6 ]. Typically, the relatively long runs of ventricular asystole are terminated with resumption of AV conduction by an appropriately timed escape or premature beat that resets the membrane action potential to its resting state [ 7 ]. Less commonly, as shown in our case, an increase in the sinus rate (from 941 ms to 640 ms) permits the return of 1: 1 AV conduction ( Figure 2 ).…”

Section: Discussionmentioning

confidence: 99%

Pause-Dependent Paroxysmal Episode of Third-Degree Atrioventricular Block Triggered by Premature Atrial Contraction

Di,

Lin

2024

Am J Case Rep

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Patient: Male, 65-year-old Final Diagnosis: Atrioventricular block Symptoms: Syncope Clinical Procedure: — Specialty: Cardiology Objective: Rare disease Background: Paroxysmal third-degree atrioventricular block (AVB) can exhibit a vast array of symptoms, but commonly, paroxysmal AVB leads to presyncope, syncope, or possibly sudden cardiac death. We present a rare case of pause-dependent paroxysmal AVB that was triggered by a premature atrial contraction. Case Report: A 65-year-old man with frequent episodes of presyncope and syncope for 3 weeks was admitted to our hospital for further diagnosis. A resting 12-lead electrocardiogram showed an incomplete right bundle branch block, and a 24-h Holter recording showed multiple episodes of third-degree AVB. Intracardiac tracing revealed that the block site was distal, at the infra-His-Purkinje system. Conclusions: This case highlights a rare case of pause-dependent paroxysmal AVB that was triggered by a premature atrial contraction. This type of AVB is an abrupt, unexpected, repetitive block of atrial impulses as they propagate to the ventricles. It is relatively rare, and due to its transient nature, it is often under recognized and can lead to sudden cardiac death.

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Section: Discussionmentioning

confidence: 99%

Pause-Dependent Paroxysmal Episode of Third-Degree Atrioventricular Block Triggered by Premature Atrial Contraction

Di,

Lin

2024

Am J Case Rep

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“…Prolongation of the P-P interval during sinus rhythm, a long pause after premature atrial contraction, or a premature ventricular contraction can cause slow spontaneous depolarization of a diseased His-Purkinje system [ 1 , 5 , 6 ]. PCAB as defined is always due to disease in the His-Purkinje system and can cause spontaneous phase 4 depolarization when the sodium channels are inactive.…”

Section: Discussionmentioning

confidence: 99%

“…PCAB as defined is always due to disease in the His-Purkinje system and can cause spontaneous phase 4 depolarization when the sodium channels are inactive. Usually after a long pause, the site of the diseased His-Purkinje cells continues to depolarize and become less responsive to continuous impulses [ 6 ]. El-Sherif and Jalif performed an unpublished series of 42 paroxysmal AV block cases [ 5 ].…”

Section: Discussionmentioning

confidence: 99%

A Case of Symptomatic Paroxysmal Complete Atrioventricular Block

Casey¹,

Bahekar²,

Patel³

et al. 2023

Cureus

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Paroxysmal complete atrioventricular block (PCAB) is clinically characterized by a sudden change from 1:1 atrioventricular (AV) conduction leading to complete heart block. Patients may have a vast array of symptoms, but commonly, PCAB will lead to syncope and possible sudden cardiac death. The literature currently consists of three different types of PCAB: intrinsic paroxysmal atrioventricular block, extensive vagal paroxysmal atrioventricular block, and extrinsic idiopathic paroxysmal atrioventricular block. Currently, there is no single symptom or sign that is specific to a single type of AV block. PCAB is often missed or overlooked because of its unpredictability and no evidence of conduction disease with a normal 1:1 conduction on routine electrocardiograms. Here, we present a case of a 65-year-old female who has been intermittently symptomatic for four years and was found to have PCAB.

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“… 1 Typically prolongation of the P-P interval of the sinus rhythm or the long pause after PAC, PVC, or termination of tachycardia can cause slow spontaneous depolarization of the diseased His-Purkinje system. 2 , 3 , 4 It can cause unresponsiveness of the His-Purkinje system because the membrane potential reaches over the threshold. Under this condition, the next impulses from the atrium are blocked.…”

Section: Discussionmentioning

confidence: 99%

“…AVB typically recovers when a PVC resets the membrane potentials to the resting state, and the next P wave occurs before the phase 4 resting potential again rises to the point where AVB would recur. 4 Retrograde conduction tends to be preserved during paroxysmal AVB. 1 In Figure 1D , a retrograde P wave (arrowhead) appeared after the first PVC during paroxysmal AVB.…”

Section: Discussionmentioning

confidence: 99%