Complete Heart Block

Question 1

Describe complete heart block

Answer 1

An electrical issue of the heart

• the AV node does not depolarise
• so does not pass on the electrical conduction to the ventricles
• so ventricles don’t contract via the normal system - a slower back up contraction system takes over
• the slower ventricular contraction causes issues with enough blood flow to tissues

Question 2

What anatomical structures are affected in complete heart block

Answer 2

AV node

Question 3

What physiology is affected in complete heart block

Answer 3

• transmission of electrical waves of depolarisation from atria to ventricles

Question 4

Structural abnormalities of complete heart block

Answer 4

• av node fibrosis
• cannot transmit electrical impulse from av node to ventricles = complete failure of AV node
• AV node may be necrosed or infarcted - death of cells from coronary artery disease

Question 5

What happens physiologically in complete heart block?

Answer 5

• atria have own electrical activity so continue regular contraction on their own
• ventricles contact at their own much slower rate

Question 6

What can cause CHB

Answer 6

• myocardial infarction - fibrosis and necrosis potentially
• rate lowering drugs - digoxin,verapamil which block av node

Question 7

Symptoms of CHB

Answer 7

• Light headedness
• presyncope or syncope
• chest pain (esp with co-existent coronary artery disease)
• heart failure signs

Question 8

Clinical signs of CHB

Answer 8

Slow pulse rate - slower than 60 BPM

LOW blood pressure

Cardiac syncope causing them to loose consciousness Jed for some seconds

Question 9

What may paramedic staff give someone immediately if they are experiencing CHB

Answer 9

Atropine:
- blocks parasympathetic firing, lowers ACH allowing HR to rise

Temporary pacemaker

Question 10

What prevention is given if complete heart block persists despite patient recovering from associated myocardial infarction?

Answer 10

Permanent pace maker