8. Rhythm recognition

Question 1

In an emergency situation, are defibrillator pads or dedicated ECG leads better for rhythm monitoring?

Answer 1

Defibrillator pads are better as they allow for rhythm monitoring and defibrillation

Question 2

What are the different components of an ECG waveform?

Answer 2

Question 3

What are the normal intervals for cardiac ECG?

Answer 3

P wave duration: ≤ 0.12s (3 small squares)

PR interval: 0.12-0.22s (3-5 small squares)

QRS complex duration: ≤0.12s (3 small squares)

Corrected QT interval (QT_c): ≤0.45s (Male), ≤0.47s (Female)

Question 4

In cases of complete ventricular standstill, what is the most effective first-line treatment?

Answer 4

Pacing

Question 5

What is the scale of ECG paper?

Answer 5

• One small horizontal space = 40ms
• One second = 5 large squares
• One small vertical space = 0.1mV

Question 6

What techniques can be used to estimate the heart rate from rhythm strip?

Answer 6

1. Count number of QRS complexes in 30 large squares and multiply by 10
2. Count number of QRS complexes in whole rhythm strip and multiply by 6
3. Count number large squares between QRS complexes and divide into 300

Question 7

What special considerations should be taken when dealing with Trosade de Pointes VT?

Answer 7

1. Avoid amiodarone and other drugs that prolong QT
2. Give magnesium
3. Correct underlying electrolyte abnormalities including hypokalaemia and hypomagnesaemia

Question 8

Patients with which types of heart block are at risk of asystole?

Answer 8

1. 2nd degree Mobitz II block
2. 3rd degree heart block

Question 9

What is an indioventricular rhythm?

Answer 9

Rhythm arising from ventricular myocardium