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Flashcards in Heart Block Deck (14):
1

How long is a normal QRS in seconds?

0.06-0.12 seconds

2

How long can a normal QT interval be?

0.44 seconds

3

What normally causes a heart block?

Abnormal conductance of the action potential at the AVN

4

What is a first degree heart block?

An extended PR interval of over 0.20, requires no treatment

5

Second degree mobitz type 1 heart block is?

Progressive prolongation of the PR interval culminating in a non-conducted P wave. Doesn't usually require any intervention either

6

Second degree mobitz type 2 heart block is?

Constant PR interval with intermittently non-conducted P waves and is caused by a conduction disorder in the bundle of Hiss. Always SINISTER and requires pacemaker

7

Third degree heart block is?

Complete AV node dissociation causing a ventricular escape rhythm at around 30BPM. Results in narrow QRS if from the bundle of Hiss and broad if it's originating in the ventricles. Requires pacemaker

8

What are bundle branch blocks

Abnormal conduction patterns causing the QRS to become longer than 0.12 as bundles conduct slowly and late

9

What does it mean for those reading the ECG of someone with a LBBB?

No interpretations can be made about the ST segment or T wave

10

Signs of RBBB

QRS >0.12 seconds and secondary R wave and slurred S wave. Results in M appearance in V1-3 and W appearance in V6

11

Signs of LBBB?

QRS >0.12 seconds M pattern in V5 and inverted T waves in leads I, aVL, V5-V6

12

Causes of RBBB

PE and pulmonary heart disease

13

Causes of LBBB

IHD, cardiomyopathy, idiopathic fibrosis

14

What is the normal length of a PR interval in seconds?

0.12-0.20 seconds