Week 3 - Arrhythmias

Question 1

ECG

PR, QRS, QT interval representations

Answer 1

PR = slow conduction through AV node.
QRS = slow conduction through ventricular myocardium.
QT = repolarisation of ventricles.

Normal PR = <200ms
Normal QRS = <110ms
Normal QT = <460ms

Question 2

Reading ECG

Bradycardia’s

Answer 2

1. Are QRS complexes regular?
   - If yes, is there P wave before each with normal PT interval.
   - If yes - SInus rhythm.
   - If no - heart block
2. QRS complexes regular or irregular?
   - if irregular, can you see P waves?
   - if no - Slow AFib
   - if yes - understand relationsip.

Question 3

First vs Second vs Third Degree

Heart Block

Wenckebach
Mobitz Type 2

Answer 3

1st: Normal QRS. Prolonged PR interval.

2nd: Irregular QRS. PR interval increases until dropping out.

Mobitz T2: 2 P waves for every QRS.

3rd: Regular QRS. Not synchronous.

Question 4

ECG

Tachycardia’s

Answer 4

Narrow (<120ms QRS)
1. QRS complexes regular?
- if <120 bpm at rest then sinus tachy. if >140 than pathological SVT.
2. QRS complexes irregular?
- AFib.
Broad (>120ms QRS)
1. V tach.

Irregular QRS?
- AFib + BBB

Adenosine blocks AV node. Slows rate if its SVT. No effect if VT.