EKG lecture II-Rhythm 2

EKG Lecture II: Rhythm Overview

I. Normal Rhythm

• Normal Sinus Rhythm (NSR)

  • Criteria:

    • HR: 60-99 bpm

    • SA node pacing (confirmed by P wave consistency in Lead II)

    • Regular R to R intervals

    • Each P wave followed by a QRS

II. Deflections on EKG

• Upward Deflections: Positive

• Downward Deflections: Negative

• Direction of current affects appearance on EKG:

  • Towards positive electrode: Upward

  • Towards negative electrode: Downward

III. Types of Dysrhythmias

• Definition: Abnormal rhythms (arrhythmia/dysrhythmia are synonymous)

• Supraventricular Dysrhythmias: Rhythms originating above the ventricles

  • Examples:

    • Sinus tachycardia/bradycardia

    • PAC

    • Atrial fibrillation

    • Atrial flutter

    • Multifocal atrial tachycardia (MAT)

A. Atrial Fibrillation

• Multi-foci issue, no single impulse causing atrial depolarization

• Heart rate: Up to 500 bpm

• Irregularly irregular ventricular rate (120-180 bpm)

• Risk factors: Hypertension, mitral valve disease, coronary artery disease

• Most common arrhythmia, increases stroke risk

B. Atrial Flutter

• Atrial rate: 250-350 bpm

• Ventricular rate varies

• Sawtooth pattern in Lead II

C. Multifocal Atrial Tachycardia (MAT)

• Irregular rate: 100-200 bpm; multiple ectopic foci

• Each P wave appears different; PR intervals vary

• Common in pulmonary patients, does not usually require treatment

IV. Ventricular Rhythms

• Normal Conduction

  • Narrow QRS (< 0.10s)

  • T wave: Larger than P wave

  • QT interval: .38-.44s, depends on HR

V. Ventricular Dysrhythmias

• Types include:

  • PVCs (Premature Ventricular Contractions)

  • Ventricular Tachycardia (V tach)

  • Ventricular Fibrillation (V fib)

  • Asystole

A. PVC

• Early, wide QRS (>0.10s)

• No P wave preceding the PVC

• Can be unifocal or multifocal

• Causes: Stimulants, sepsis, stress

B. V Tach

• Three or more consecutive PVCs without a compensatory pause

C. Ventricular Fibrillation (V fib)

• A pre-terminal event, no true QRS complex

• Immediate CPR and defibrillation required

VI. Atrioventricular (AV) Blocks

• Definition: Delay or obstruction in conduction between atria and ventricles

• Types of AV Blocks:

  • First Degree

  • Second Degree (Wenckebach, Mobitz Type I and II)

  • Third Degree

A. First Degree AV Block

• Prolonged PR interval (>0.20s)

• All atrial impulses make it through to ventricles

• Common in healthy hearts; does not need treatment

B. Second Degree AV Block: Mobitz Type I (Wenckebach)

• Progressive lengthening of PR interval until a P wave fails to conduct

C. Second Degree AV Block: Mobitz Type II

• Some atrial impulses fail to conduct, but no progressive lengthening

D. Third Degree AV Block

• No atrial impulses reach ventricles (complete heart block)

• Ventricular escape rhythm (30-45 bpm), atrial rate 60-99 bpm

• Diagnosis requires AV dissociation (ventricular rate slower than atrial rate)

VII. Key Takeaways

• Understanding the origin and characteristics of arrhythmias is critical for diagnosis and management.

• Monitor EKG for regularity, rate, and deflections to assess heart rhythm.