First-Degree Heart Block:
- Description: The electrical signals are delayed as they pass through the atrioventricular (AV) node, but all signals eventually reach the ventricles.
- ECG Findings: Prolonged PR interval (>200 ms)
- Symptoms: Usually asymptomatic
- Treatment: Generally, no treatment is required.
Second-Degree Heart Block (Type I or Mobitz I/Wenckebach):
- Description: Progressive lengthening of the PR interval until a QRS complex is dropped.
- ECG Findings: Increasing PR interval with dropped QRS complex
- Symptoms: May be asymptomatic or may experience dizziness
- Treatment: Close monitoring, may require a pacemaker
Second-Degree Heart Block (Type II or Mobitz II):
- Description: Some electrical signals are blocked, leading to dropped QRS complexes without PR interval prolongation.
- ECG Findings: Dropped QRS complexes with constant PR interval
- Symptoms: Dizziness, fainting
- Treatment: Usually requires a pacemaker
Third-Degree Heart Block (Complete Heart Block):
- Description: No electrical signals from the atria reach the ventricles.
- ECG Findings: Atria and ventricles beat independently
- Symptoms: Fatigue, dizziness, fainting
- Treatment: Requires immediate pacemaker implantation