Lecture Notes on ECG and Heart Blocks

Overview

• Discussing ECG interpretation, specifically focusing on heart block classifications and treatment options.

Case Presentation

• Patient: 66-year-old woman, asymptomatic.
• Need to determine diagnosis and treatment based on ECG findings.

Misleading Answer Choices

• Choices A and B: First-degree heart block and Mobitz type 1 are incorrect answers.

First-Degree Heart Block

• Definition: PR interval > 200 milliseconds.
• Characteristics: P wave occurs before each QRS complex, prolonged PR interval but no treatment necessary.

Mobitz Type 1 (Wenckebach)

• Definition: Gradually prolonging PR interval followed by a dropped QRS complex.
• Characteristics: Observational pattern; can see a series of QRS complexes followed by a missing one.
• Treatment: No treatment required.

Mobitz Type 2

• Definition: Random dropping of QRS complexes without gradual PR prolongation.
• Characteristics: May present in patterns (2:1, 3:1), but lacks the gradual increase seen in type 1.
• Danger: High risk of progressing to third-degree heart block.
• Treatment: Requires pacemaker.

Third-Degree Heart Block

• Characteristics:
  • Extremely slow heart rate (30-40 bpm), QRS complexes far apart.
  • No relationship between P waves and QRS complexes.
  • Represents complete severance of electrical signals from atria to ventricles.
• Treatment: Requires pacemaker.

Key Points

• Pacemaker Indications:
  • Mobitz type 2
  • Third-degree heart block

Additional Insights

• Hisperkinje System: Can be involved in Mobitz type 2 and third-degree heart blocks.
• Sodium Channel Blockers:
  • Canide: Type 1C sodium channel blocker; first-line rhythm control for atrial fibrillation without structural or coronary artery disease.

Incorrect Answer Choices

• Wolf-Parkinson-White Syndrome: Procan is a treatment option; characterized by re-entrant tachycardia and delta wave on ECG.

Conclusion

• Understanding ECG interpretation and treatment for different heart blocks is crucial for internal medicine and cardiology.
• Keep practicing ECGs for better proficiency.