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Understanding Ventricular Rhythms and PVCs

May 6, 2025

ECG Interpretation Made Easy: Ventricular Rhythms

Introduction to Ventricular Rhythms

  • Ventricular rhythms include:
    • Premature Ventricular Complexes (PVCs)
    • Ventricular Tachycardia
    • Ventricular Fibrillation
  • Focus of this video: Premature Ventricular Complexes

Basic Understanding of Heart Electrical Activity

  • SA Node: Primary pacemaker, initiates electrical currents causing atrial contraction.
  • AV Node: Takes over if SA node fails, conducting signals to the bundle branches and Purkinje fibers, leading to ventricular contraction.
  • Purkinje Fibers: Step in if SA and AV nodes fail.
  • Ventricular Tissue: Last resort, producing electrical currents if all else fails, but indicates abnormality.

Ventricular Rhythms

  • Generated when atria and AV junction fail to initiate a beat.
  • Types of ventricular rhythms:
    • Ventricular Tachycardia
    • Ventricular Fibrillation
    • Polymorphic Ventricular Tachycardia
    • Premature Ventricular Complexes

Causes and Consequences of Ventricular Rhythms

  • Can occur due to myocardial infarction and ischemia.
  • Damaged tissue may produce abnormal electrical currents, potentially leading to cardiac arrest.

Morphology of Ventricular Rhythms

  • Characterized by:
    • Wide, bizarre QRS complexes
    • T wave inversion
    • P waves usually hidden or absent
    • QRS interval > 0.12 seconds
  • Comparison with normal sinus beat:
    • Normal: Narrow QRS, visible P wave
    • Ventricular: Wide QRS, no visible P wave

Premature Ventricular Complexes (PVCs)

  • Occur when ectopic ventricular focus disturbs normal sinus rhythm.
  • Caused by irritable focus in ventricular wall or re-entry phenomena.
  • Often linked to myocardial damage.

Significance of PVCs

  • May be asymptomatic but indicate potential for serious conditions like ventricular tachycardia or fibrillation.
  • Can decrease cardiac output if frequent.

Types of PVC Patterns

  • Bigeminy: Every normal beat followed by PVC.
  • Trigeminy: Every two normal beats followed by PVC.
  • Quadrigeminy: Every three normal beats followed by PVC.
  • PVC Couplets: Two PVCs occur together.

ECG Interpretation of PVCs

  • Use the 6-second method for heart rate calculation in irregular rhythms.
  • Count QRS complexes in 30 large boxes, multiply by 10.
  • Identify features like wide QRS and inverted T wave for PVCs.

Management of PVCs

  • Most patients are asymptomatic and may not require treatment.
  • Recommended to perform an echocardiography to identify underlying cardiac defects.
  • Symptomatic patients may be treated with beta-blockers or catheter ablation.

Summary

  • Covered ventricular rhythms, their causes, morphology, and the significance and management of PVCs.

The lecture emphasized understanding the electrical activity of the heart and identifying abnormal rhythms, particularly focusing on premature ventricular complexes and their implications in cardiac health.

Full transcript