Normal ECG

Question 1

Define the normal P wave in the ECG ?

Answer 1

Represents(the wave of depolarisation)that spreads from the SA node throughout the atria

Question 2

What does the normal P wave represent in the ECG ?

Answer 2

Atrial depolarisation

Question 3

What is the duration of the normal P wave in the ECG in seconds and milliseconds?

Answer 3

0.08-0.1 seconds

80-100 ms

Question 4

Define the isoelectric period after the P wave in the ECG ?

Answer 4

Represents the time in which the impulse is travelling within the AV node.

Question 5

Define the normal PR interval in the ECG ?

Answer 5

Time from the onset of the P wave to the beginning of the QRS complex.

Question 6

What is the duration of the normal PR interval in the ECG in seconds ?

Answer 6

0.12-0.20 seconds

Question 7

What does the PR interval represent in the normal ECG ?

Answer 7

Represents the time between the onset of atrial depolarisation and the onset of ventricular depolarisation.

Question 8

What does the QRS complex represent in the normal ECG ?

Answer 8

Ventricular depolarisation

Question 9

What is the duration of the normal QRS complex in the ECG in seconds ?

Answer 9

0.06-0.1 seconds

Question 10

Define the normal ST segment in the ECG ?

Answer 10

Is the isoelectric period following the QRS complex.

Question 11

What does the normal ST segment represent in the ECG ?

Answer 11

• Represents period which the entire ventricle is depolarised(ventricular
  depolarisation) .
• Roughly corresponds to the plateau phase of the ventricular action potential.

Question 12

What is the relationship between the ST segment and the ventricular action potential ?

Answer 12

Roughly corresponds to the plateau phase of the ventricular action potential.

Question 13

What does the normal T wave represent in the ECG ?

Answer 13

Ventricular repolarisation.

Question 14

What is the significance of the (small positive U wave) after the T wave in the ECG ?

Answer 14

Represents the last remnants of the ventricular repolarisation.

Question 15

What does the normal QT interval represent in the ECG ?

Answer 15

Represents both of the ventricular depolarisation and repolarisation.

Question 16

What is the relationship between the QT interval and the ventricular action potential ?

Answer 16

Roughly estimates the duration of an average ventricular action potential.

Question 17

What is the duration of the normal QT interval in the ECG in seconds ?

Answer 17

0.2-0.4 seconds depending on heart rate.

Question 18

What is the relationship between the duration of the normal QT interval and heart rate ?

Answer 18

The normal QT interval is 0.2-0.4 seconds depending on heart rate.
At high heart rate:-
1.ventricular action potential shortens in duration
2.Decrease in the QT interval

Question 19

Define the normal RR interval in the ECG

Answer 19

It is between ventricular depolarisation.

Question 20

Define the corrected QT interval ?

Answer 20

QT/Square root of the RR interval.

Question 21

What is the significance of the corrected QT interval in the ECG ?

Answer 21

Assesses the QT interval that is independent on heart rate.

Question 22

What is the normal duration of the normal corrected QT interval ?

Answer 22

0.44 seconds