- First degree AV block, right bundle branch block, and left anterior hemiblock
- Conduction disease of all three fascicles: fight bundle branch, and left posterior and left anterior fascicles
- Trifascicular blocks can deteriorate into high grade blocks
- ECG will show a bifascicular block and a prolonged PR interval
Differential includes ischemic events, electrolyte abnormalities, and medication overdoses in addition to rheumatologic conditions
Types of second degree AV block
Bundle and Fascicular Blocks
2nd degree AV Block Type 2 (4:3 conduction)
2nd degree AVB, 2:1 conduction, LBBB with buried p-waves in t-waves
- Evaluate for underlying pathology
- Prolongation of the PR interval (first degree AV block) AND
- Right bundle branch block AND
- Either left anterior fascicular block or left posterior fascicular block
- ECG will show more atrial complexes than ventricular complex indicating high grade heart block
- Right budle branch block + extreme left axis deviation (left anterior fascicular block) + atrioventricular heart block
- Symptomatic patients should be admitted for monitoring and evaluation for a permanent pacemaker
- Cardiology consult
- ↑ Hampton, JR. The ECG in Practice (5th edition), Churchill Livingstone 2008.
- ↑ Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.
- ↑ Sovari AA et al. Second-Degree Atrioventricular Block Treatment & Management. eMedicine. Apr 28, 2014. http://emedicine.medscape.com/article/161919-treatment#showall.