Second Degree AV Block, Mobitz Type II
Second Degree AV Block, Mobitz Type II
David Ray Velez, MD
Intermittent Interruption of Impulse Transmission from the Atria to the Ventricles with Sudden Dropped Beats and No Progressive Preceding PR Prolongation
- Rarely Seen in Patients Without Underlying Heart Disease
- Significantly Higher Risk than Mobitz Type I (Wenkebach) for Severe Bradycardia, Conversion to Third Degree (Complete) Heart Block, and Hemodynamic Instability
EKG Pattern
- Normal PR Interval (120-200 ms)
- Sudden Dropped Beats
- P Waves “March” Through at a Constant Rate
Second Degree AV Block, Mobitz Type II
Pathologic Causes
- Myocardial Infarction (MI)
- Electrolyte Derangements
- Cardiomyopathy
- Myocarditis
- Post-Cardiac Surgery
- Medications (Beta-Blockers, Calcium Channel Blockers, Digoxin, etc.)
Treatment
- Unstable: Temporary (Transcutaneous) Cardiac Pacing
- May Consider Beta-Adrenergic Agonists if Myocardial Ischemia is Unlikely
- Options: Dopamine, Dobutamine, Epinephrine
- Generally Avoid Atropine – May Paradoxically Worsen Bradycardia by Increasing Conduction Across the AV Node
- *See Antiarrhythmic Pharmacology
- May Consider Beta-Adrenergic Agonists if Myocardial Ischemia is Unlikely
- Stable: Permanent (Transvenous) Pacemaker Placement