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Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

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Bradyarrhythmias are cardiac rhythm disorders characterized by a slower-than-normal heart rate, typically defined as fewer than 60 beats per minute. Some of which are discussed here:Sinus BradycardiaSinus bradycardia presents a heart rate lower than 60 beats per minute, with a regular rhythm originating from the SA node. The ECG typically shows normal P waves preceding each QRS complex, a normal PR interval (0.12 to 0.20 seconds), and a normal QRS duration (0.06 to 0.10 seconds).First-Degree AV...
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Arrhythmia is a condition characterized by an irregular heart rhythm, with ECG changes that differ based on its origin and nature. The types of arrhythmias discussed below include atrial, junctional, and ventricular arrhythmias.Atrial ArrhythmiasPremature Atrial Complexes (PACs): PACs are early atrial beats caused by stress, caffeine, alcohol, electrolyte imbalances, hypoxia, hyperthyroidism, or certain medications (e.g., bronchodilators and decongestants). The ECG shows early P waves with an...
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The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase...
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Mitral Stenosis II: Clinical features and Diagnostic Tests01:23

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Mitral stenosis is a heart condition in which the mitral valve, which allows blood to flow from the left atrium to the left ventricle, becomes narrowed or stenotic. This narrowing hinders blood flow and leads to clinical symptoms requiring specific medical evaluations and management strategies. The following overview outlines the clinical symptoms, assessments, diagnostic findings, prevention methods, and treatments for mitral stenosis.Clinical ManifestationsDyspnea (shortness of breath): This...
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An electrocardiogram (ECG or EKG) is a critical diagnostic tool that records the electrical signals produced by the heart during each heartbeat. This recording is achieved through electrodes placed strategically on the arms, legs, and chest. The electrocardiograph amplifies these signals and produces 12 distinct tracings, offering a comprehensive understanding of the heart's electrical activity.
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An electrocardiogram (ECG)graphically represents the heart's electrical activity on ECG paper or a monitor.
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M-beat-A novel marker for selective left bundle branch capture.

Shunmuga Sundaram Ponnusamy1, William Basil2, Pugazhendhi Vijayaraman3

  • 1Department of Cardiology, Velammal Medical College, Madurai, India.

Journal of Cardiovascular Electrophysiology
|June 13, 2022
PubMed
Summary

A novel M-beat during premature-ventricular-complexes (PVC) guided left bundle branch pacing (LBBP) predicts selective LBB capture with high accuracy. This finding simplifies lead deployment and reduces procedure time.

Keywords:
M-beatleft bundle branch pacingpremature ventricular complexesselective LBB capturetemplate beats

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Area of Science:

  • Electrophysiology
  • Cardiology
  • Medical Device Technology

Background:

  • Left bundle branch pacing (LBBP) is an emerging technique for cardiac pacing.
  • Premature-ventricular-complexes (PVC) guided pacing offers a method for lead deployment.
  • A unique 'M-beat' morphology during PVC-guided LBBP has been observed.

Purpose of the Study:

  • To analyze the incidence of the M-beat during PVC-guided LBBP.
  • To evaluate the M-beat's ability to predict selective left bundle branch (LBB) capture.
  • To determine the clinical significance of the M-beat in LBBP procedures.

Main Methods:

  • Analysis of 217 patients undergoing PVC-guided LBBP.
  • Identification and characterization of the M-beat morphology.
  • Comparison of procedural parameters (fluoroscopy time, lead deployment attempts) between patients with and without M-beats.

Main Results:

  • Successful LBBP was achieved in 96.7% of patients.
  • M-beats were observed in 32.8% of patients, associated with significantly less fluoroscopy time and fewer lead deployment attempts.
  • M-beat demonstrated high specificity (96.77%) and positive predictive value (98.55%) for predicting selective LBB capture, independent of baseline QRS morphology.

Conclusions:

  • The M-beat is a reliable marker for transient selective LBB capture during PVC-guided LBBP.
  • This electrophysiological finding is independent of local myocardial excitability.
  • The M-beat aids in optimizing LBBP lead placement, reducing procedural complexity and duration.