Heart Block

Question 1

Heart Block First Degree

Answer 1

• PR interval greater than 0.2s
• Common condition
• Caused by; post MI, lyme, SLE, AV node disease, myocarditis, medication
• Does not require Ix if asymptomatic

Question 2

Heart Block Second Degree

Answer 2

Prolongation with intermittent failure causing dropped beats, usually associated with cardiac pathology

• Mobitz type I and II
• Causes same as first degree

Question 3

Heart Block Third Degree

Answer 3

• Complete failure of transmission
• P waves occur regularly, completely unconnected to QRS complexes
• Block can occur in node or below node in His-Purkinje system
• Nodal block; subsidiary pacemaker above or in bundle of His, QRS narrow , more asymptomatic
• Blocks below His; subsidiary pacemaker in left or right bundle branches; wide QRS complexes, slow HR, patient harm-dynamically compromised and overtly symptomatic