ECG

Question 1

Difference between Electrocardiograph vs Electrocardiogram

Answer 1

The recording device is known Electrocardiograph.

A recording of such potential is known as electrocardiogram.

Question 2

What constitutes an electrical vector?

Answer 2

Magnitude and direction

Question 3

What generates a upward deflection on the ECG?

Answer 3

When depolarization moves towards the recording electrode, it generates an upward deflection on the ECG

Question 4

What generates a downward deflection on the ECG?

Answer 4

When depolarization moves away from the recording electrode, it generates a downward deflection on the ECG

Question 5

What comprises the standard 12 lead ECG?

Answer 5

Three standard limb leads (I, II and III) – these are termed bipolar
Three augmented voltage (aV) leads [aVR (right), aVL (left) and aVF (foot)] – these are termed unipolar (Vertical/frontal)
Six chest leads (V1 – V6) (aka precordial leads) (Transverse)

Question 6

What are the standard limb reads?

Answer 6

Lead I: RA-ve to LA+ve
Lead II: RA-ve to LL+ve
Lead III: LA-ve to LL+ve

Question 7

Significance of the P wave in an ECG

Answer 7

The P wave represents atrial depolarisation. Normal duration is less than 120ms

Question 8

Significance of the QRS wave in an ECG

Answer 8

The QRS complex represents ventricular activation or depolarization. Normal duration of 100ms.

Question 9

Significance of individual QRS wave in an ECG

Answer 9

Ventricular depolarization starts in the interventricular septum and spreads from left to right causing the small and narrow Q wave
Subsequently the main free walls of the ventricles depolarize causing a tall and narrow R wave
The ventricles at the base of the heart depolarize, producing a small and narrow S wave

Question 10

Significance of individual T wave in an ECG

Answer 10

The T wave represents ventricular repolarization