Complete Heart Block

Question 1

Anatomical structures affected

Answer 1

AV node

Question 2

Structural abnormalities

Answer 2

Fibrosis of AV node

Necrosis/infarction of AV node (result of coronary artery disease)

Question 3

Physiological abnormalities

Answer 3

Complete failure of AV node to transmit electrical impulse from atria to ventricles
Atria contract independently of ventricles which develop their own pacemaker activity (slower rate)

Question 4

Prior events

Answer 4

Elderly patient; prior MI–> taking beta blockers, rate lowering drugs (digoxin, verapamil) that block AV node

Question 5

Symptoms

Answer 5

Can either be gradual and isolation- chronic complete heart block–. tiredness and breathlessness with exercise
Or acute: light headedness or collapse with loss of consciousness
If caused by coronary artery disease- angina or MI

Question 6

Signs

Answer 6

Pulse/heart rate is slow (often much lower than 60 bpm)
Blood pressure low
Cardiac syncope- loss of consciousness for some seconds

Question 7

Medical/surgical intervention

Answer 7

Ambulance; atropine- blocks vagus nerve and acetyl choline –> heart rate rises
Temporary pacemaker- immediately on arrival at hospital

Question 8

Primary and secondary prevention

Answer 8

May need permanent pacemaker