His Bundle Extrasystoles Revisited: The Great Electrocardiographic Masquerader

Section: Discussionsupporting

confidence: 89%

Irregular narrow QRS complex tachycardia with intermittent P‐waves linked to two QRS complexes: What is the mechanism?

Ding

Gao

et al. 2019

“…H depolarizations can be caused by abnormal automaticity or triggered activity and are often associated with His‐Purkinje system disease . Depending on the ECG findings and patient symptoms, the H ectopy has been treated with class I antiarrhythmic drugs, catheter ablation, and permanent pacemaker implantation …”

Section: Discussionmentioning

confidence: 99%

Mobitz Type II Second‐Degree Atrioventricular Block with Narrow QRS and Junctional Extrasystoles: What is the Mechanism?

Jiménez‐Díaz

González-Ferrer

Heredia

et al. 2013

A 74-year-old man underwent an electrophysiological study because of Mobitz type II second-degree atrioventricular (AV) block with narrow QRS and frequent junctional extrasystoles. During the study, there were very frequent single His bundle depolarizations with multiple coupling intervals that reproduce the ECG findings. In this case, some His bundle extrasystoles result in retrograde concealed conduction and prolonged local refractoriness in the AV node that manifest as block of the next atrial impulse.

“…His extrasystole may resemble various degrees of heart block, ectopy, or tachycardia. First and second degree (Mobitz type I, II) AV block, 2:1 AV conduction, alternation of PR interval, blocked premature atrial complexes, AV junctional rhythm, junctional tachycardia, and premature ventricular complexes have been reported to resemble ECG findings of His extrasystole …”

Section: Commentarymentioning

confidence: 99%

“…In an asymptomatic patient without evidence of left ventricular dysfunction, conservative management with observation can be considered. However, in patients who are symptomatic either from ectopy itself or conduction block due to ectopy, lidocaine, quinidine, and procainamide have been reported to suppress the ectopy . If the patient continues to have conduction block due to extrasystole despite using medications, permanent pacemaker therapy has been attempted …”

Section: Commentarymentioning

confidence: 99%

Two QRS Complexes for a Single P Wave: What is the Mechanism?

Tanawuttiwat

Marine

2014

Case PresentationA 49-year-old man with hypertension was found to have an irregular heart rhythm during preoperative evaluation for kidney stone. The patient also noted fatigue, neck throbbing, and dyspnea on exertion for 6-8 months. Echocardiogram showed mild left ventricular dysfunction with ejection fraction of 40%. Coronary angiogram revealed nonobstructive coronary artery disease. An initial trial of dronedarone was discontinued due to gastrointestinal side effects. He was subsequently referred to our center for second opinion. The initial electrocardiogram (ECG) is shown in Figure 1. During the electrophysiology study, the baseline intracardiac electrogram demonstrated a single atrial activity following by 2 Hisian activities (Fig. 2). What is the mechanism of arrhythmia in this case? CommentaryAt a glance, the baseline ECG in this case (Fig. 1) showed a pattern of grouped beating. There was an absence of nonconducted P wave and the P waves of the first and third beats in each group were marching through with the cycle length of approximately 1,000 milliseconds. These findings suggested that the patient was in normal sinus rhythm with an additional QRS complex representing the second beat in each group. The similarity of the QRS morphology between ectopic beat and sinus beat excluded ventricular or fascicular ectopy and was consistent with supraventricular origin. Given these findings on the baseline ECG, there were 3 possible mechanisms of the ectopic beats: premature atrial complex, 1:2 Atrioventricular (AV) node physiology, and AV nodal or Hisian ectopy. The 1:2 AV node physiology refers to an antegrade conduction of sinus rhythm through both the fast and slow AV nodal pathways. Of note, the PR interval of