ECG

Question 1

When is the measured potential difference greatest (when lead axis is parallel or perpendicular to the direction of the dipole)?

Answer 1

parallel (is close to 0 when perpendicular)

Question 2

Which leg is earthed?

Answer 2

right leg

Question 3

During which parts of the ECG is it isoelectric?

Answer 3

PR, ST and TP

Question 4

Which limb lead is inverted and why?

Answer 4

AVR - predominant vector is depolarization moving away from the electrode

Question 5

In which limb lead is there poorly resolved P and T waves and why?

Answer 5

Lead III predominant vector is approximately perpendicular to the lead axis

Question 6

In which limb lead is there well resolved P and T waves and why?

Answer 6

II, predominant vector is approximately parallel to the lead axis

Question 7

How can heart rate be calculated on an ECG?

Answer 7

300/number or large squares between beats

Question 8

Which lead is normally the rhythm strip?

Answer 8

II

Question 9

A 12 lead ECG can help find any voltage criteria changes. what can this be useful to diagnose?

Answer 9

chamber hypertrophy

Question 10

What questions should you ask yourself while interpreting an ECG?

Answer 10

Is electrical activity present?
Is the rhythm regular or irregular?
What is the heart rate?
P-waves present?
What is the PR interval?
Is each P-Wave followed by a QRS complex? 
Is the QRS duration normal?

Question 11

What significant diseases may an ECG not rule out?

Answer 11

Stable angina, NSTEMI, intermittent rhythm disturbance