Conduction Blocks

Question 1

What is an AV block (AVB)?

Answer 1

Delay or disruption in the transmission of an impulse from the atria to the ventricles. Having Anatomical impairment and Functional impairment

Question 2

Describe first Degree AVB?

Answer 2

AV synchrony is maintained. Prolonged PR interval. Delay at AV node.

Question 3

Describe Second Degree AVB?

Answer 3

Intermittent loss of AV conduction. Dropped beats.

Question 4

Describe Third Degree AVB?

Answer 4

Complete AV dissociation

Question 5

Name the two most common etiologies of AVB?

Answer 5

1. Progressive cardiac conduction disease -most common

2. Ischemic heart disease - 2nd most common

Question 6

What is the approach to a patient with 1st degree AVB?

Answer 6

No specific work-up or treatment usually

Question 7

Describe Second Degree AV Block Mobitz Type I (Wenckebach)?

Answer 7

Progressive slowing of subsequent AV node impulses until node fails to conduct. PR interval continues to prolong until a dropped beat. Cycle repeats.

Question 8

Describe the management for Mobitz Type I?

Answer 8

• Treat underlying cause
• No specific treatment required for asymptomatic patients
• Monitor EKG periodically for progression to Type II
• If syncope or other symptoms→ refer to EP. If marked prolongation of HV conduction → consider pacemaker

Question 9

Describe Second Degree AV Block Mobitz Type II?

Answer 9

• Indicative of underlying disease of the His-Purkinje system (below AV node)
• Episodic unpredictable failure of the pathway to conduct impulse from the atria to the ventricles
• No change in PR interval
• Occasional and random dropped beats

Question 10

Treatment of Mobitz Type II?

Answer 10

Usually pacemaker

Question 11

Treatment of Third Degree AV Block?

Answer 11

• Apply temporary pacer
• Refer to EP
• Treat underlying cause
• Avoid meds that block AV node
• Permanent Pacemaker Placement (PPP) in all patients

Question 12

What should you do if you incidentally discover a LBBB in a patient without symptoms?

Answer 12

Work them up for coronary artery disease (EKG, Stress test, consider Echo)

Question 13

What is the clinical implication of incidental Right Bundle Branch Block in otherwise healthy and asymptomatic individual?

Answer 13

Nothing. No work up required.

Question 14

When is a LBBB a STEMI equivalent?

Answer 14

High risk (risk factors, good story) concern for ACS, new LBBB compared to prior EKG.