Heart blocks

Question 1

Criteria for 1st degree heart block.

Answer 1

– PR interval constant and prolonged >200ms
– No dropped beats

Question 2

Causes of 1st degree heart blocks.

Answer 2

slowing down of the impulse during conduction
through the AV node and more uncommonly the atria,
e.g. B-blockers; rarely symptomatic

Question 3

Criteria for 2nd degree heart block type 1.

Answer 3

PR interval lengthens progressively across a few cycles
– until a non-conducted P wave occurs (P with no QRS wave
following, ‘dropped QRS beat’).
– the pr interval ‘resets’ and the cycle repeats

Question 4

Causes of 2nd degree heart block type 1.

Answer 4

Benign occurrence

Question 5

Complication of 2nd type 1

Answer 5

Symptomatic Bradycardia

Question 6

Criteria of 2nd type 2.

Answer 6

PR intervals fixed + non-conducted P (‘dropped beats’)
– Dropped beats unexpected and irregular; no discernable pattern

Question 7

Causes of 2nd Type 2.

Answer 7

AV or His Ischaemia

Question 8

Criteria for 3rd.

Answer 8

P bears no relation to the QRS
– QRS ALWAYS regular, slower than normal, more P than QRS