Heart Blocks

Question 1

What’s First Degree AV Block

Answer 1

Impulse delayed at AV node
Prolonged PR interval (>0.2 seconds)

Question 2

Treatment for First Degree AV Block

Answer 2

Only when symptomatic
If a slow HR, atropine
Hold “slowing” drugs (e.g. digoxin)

Question 3

What’s Second Degree AV Block (Wenckebach)

Answer 3

Longer conduction through the AV node
PR interval varies and progressively lengthens,
Prolonged PR until no QRS

Question 4

Treatment for Second Degree AV block type1

Answer 4

Treatment:
Atropine/pacemaker if symptomatic
Hold “slowing” drugs

Question 5

What’s Second Degree AV block Type II (Wenckebach II)

Answer 5

Impulses are blocked by the AV at regular intervals
Every 2nr, 3rd, or 4th impulse reach the ventricles
(3:1, 4:1) cause slower VR, greater risk for reduced CO
Constant PR but only exists every 2nd, 3rd, or 4th beat
Wider QRS complex, more serious the block

Question 6

Treatment for second degree AV block Type II

Answer 6

Treatment:
Atropine for a narrow QRS complex
pacemaker

Question 7

What’s third degree AV block

Answer 7

Complete AV block
Severe drop in CO, cerebral ischemia
AR and VR are regular but independent of each other
Wide QRS

Question 8

Treatment for third degree AV block

Answer 8

Treatment:
Cardiac pacing
Atropine (while awaiting pacemaker insertion)
Ventricular ectopic beats can lead to VT or VF, prepare defibrillator