Lecture Notes: ECG Interpretation

Introduction

• Understanding ECG interpretation is crucial for nursing.
• Focus on recognizing essential heart rhythms.

Normal Sinus Rhythm (NSR)

• Originates from the SA node (sinoatrial node).
• Key characteristics:
  • P Waves: Present before each QRS complex, upright, <0.12 seconds.
  • Atrial Rhythm: Regular, 60-100 bpm.
  • PR Interval: 0.12-0.20 seconds.
  • QRS Complex: Follows each P wave, <0.12 seconds.
  • Ventricular Rhythm: Regular, 60-100 bpm, same as atrial rate.
  • QT Interval: 0.36-0.44 seconds.
  • T Wave: Normal, round, upright.
  • ST Segment: Flat (isoelectric).
• No treatment if stable; continue monitoring.

Sinus Bradycardia

• Originates from the SA node, but slow rate (<60 bpm).
• Characteristics:
  • Normal P waves, slow atrial rate, regular rhythm.
  • Normal QRS Complex, slow ventricular rate.
  • PR Interval: Normal.
  • QT Interval: Can be longer with slower rates.
• Causes: "SLOW RATES" mnemonic (Sick Sinus Syndrome, Low thyroid, Older age, Weak heart, etc.).
• Treatment based on symptoms; could include Atropine, Dopamine, Epinephrine.

Sinus Tachycardia

• Originates from the SA node, fast rate (>100 bpm).
• Characteristics:
  • Normal P waves, atrial rate >100 bpm, regular.
  • Normal QRS Complex, ventricular rate >100 bpm.
  • PR Interval: Normal.
  • QT Interval: Shorter with faster rates.
• Causes: "TACHY HEARTS" mnemonic (Temperature, Air aerobics, Cardiac disease, etc.).
• Treatment: Identify and treat underlying cause; medications like beta-blockers or calcium channel blockers.

Atrial Fibrillation (AFib)

• Atrial quivering, irregular rhythm.
• No P waves, replaced by irregular F waves.
• Ventricular rhythm can be controlled (<100 bpm) or uncontrolled (>100 bpm).
• Causes: Post-surgery, heart valve issues, lung conditions, etc.
• Treatment: Anticoagulants, cardioversion, medications (beta-blockers, calcium channel blockers).

Atrial Flutter

• Rapid atrial contractions, sawtooth pattern.
• No P waves, but flutter waves.
• Ventricular rate may vary.
• Causes: Heart valve issues, MI, hyperthyroidism.
• Treatment: Medications to control rate, synchronized cardioversion if unstable.

Ventricular Tachycardia (V-Tach)

• Originates in ventricles, rapid and regular.
• Wide, bizarre QRS complexes.
• Rate: 100-250 bpm.
• Causes: Electrolyte imbalances, MI, medication toxicity.
• Treatment: Antiarrhythmic meds, synchronized cardioversion, CPR if pulseless.

Ventricular Fibrillation (V-Fib)

• Chaotic, rapid rhythm, ventricles quiver.
• No organized ECG pattern.
• Causes: Severe heart disease, hypoxia, drug overdose.
• Treatment: Immediate CPR, defibrillation, medications.

Asystole

• Flat line ECG, no contraction.
• Confirm patient status; check connections.
• Causes: Progression from lethal rhythms, treat underlying cause.
• Treatment: CPR, medications, not shockable.

Pulseless Electrical Activity (PEA)

• Organized rhythm on ECG, but no pulse.
• Causes: Hypoxia, hypovolemia, electrolyte imbalances.
• Treatment: CPR, identify and treat cause, not shockable.

AV Heart Blocks

First Degree

• Prolonged PR interval >0.20 seconds.
• Asymptomatic, often monitored.

Second Degree Type 1 (Mobitz I, Wenkebach)

• Gradual PR interval lengthening, dropped QRS.
• Causes: MI, medications.
• Treatment: Monitor if asymptomatic; atropine or pacing if symptomatic.

Second Degree Type 2 (Mobitz II)

• Constant PR interval, occasional dropped QRS.
• More severe, can progress to complete block.
• Treatment: Pacing, possibly permanent pacemaker.

Third Degree (Complete Heart Block)

• No AV conduction, atrial and ventricular rhythms independent.
• Causes: Severe heart disease, MI.
• Treatment: Atropine, pacing, permanent pacemaker.

This lecture provides a comprehensive overview of key ECG rhythms important for nursing practice. Understanding these rhythms and their treatment is essential for managing patient care effectively.