A first look at the ECG

Question 1

what does a P wave represent in a normal ECG?

Answer 1

it represents atrial depolarisation

Question 2

what precedes the QRS-complex?

Answer 2

the P wave

Question 3

what does the P wave look like?

Answer 3

it looks like a small bump upwards from the baseline

Question 4

what is the amplitude of a P wave in a normal ECG?

Answer 4

the amplitude is normally 0.05-0.25mV

Question 5

what is the QRS-complex in a normal ECG?

Answer 5

it is a name for the combination of 3 of the graphical deflections seems on a typical ECG

Question 6

where is the QRS-complex on a normal ECG?

Answer 6

it is usually the central and most visually obvious part of the tracing on the ECG

Question 7

what does the QRS-complex correspond to?

Answer 7

it corresponds to the depolarisation of the right and left ventricle of the human heart

Question 8

what is the normal duration of the QRS-complex?

Answer 8

the normal duration is between 0.08 and 0.1 seconds

Question 9

what is considered an abnormal QRS-complex?

Answer 9

a QRS-complex duration of greater than 0.12 seconds

Question 10

what does the T wave in a normal ECG represent?

Answer 10

it represents the depolarisation of the ventricles

Question 11

what is referred to as the absolute refractory period?

Answer 11

the interval from the beginning of the QRS-complex to the apex of the T wave

Question 12

what is the PR interval?

Answer 12

in an ECG, the PR interval is the period, measured in milliseconds, that extends from the bringing of the P wave until the beginning of the QRS-complex

Question 13

what does the PR interval represent?

Answer 13

this interval represents the time between the onset of atrial depolarisation and the onset of ventricular depolarisation

Question 14

what does the P wave in an ECG represent?

Answer 14

it represents the onset of arterial depolarisation

Question 15

what does the PR interval correspond to?

Answer 15

it corresponds to the time lag from the onset of atrial depolarisation, this time lag allows atrial systole to occur, filling the ventricles before ventricular systole

Question 16

what is the normal range for the PR interval?

Answer 16

it is normally between 120 and 200ms in duration

Question 17

what is the normal range for the QRS-complex?

Answer 17

duration less than or equal to 0.12 seconds
amplitude greater than 0.5mV in at least one standard lead
amplitude greater than 1mV in at least on precordial lead
upper limit of normal amplitude is 2.5-3mV

Question 18

what is the normal range for the QT interval?

Answer 18

the QT interval varies depending on age and gender, but it is usually 0.36 to 0.44 seconds

Question 19

how is heart rate measured from an ECG?

Answer 19

count the number of RR intervals between 2 tick marks in the rhythm strip and multiply by 10 to get the beats per minute

Question 20

define normal sinus rhythm

Answer 20

it is the characteristic rhythm of the healthy human heart

Question 21

what is normal sinus rhythm?

Answer 21

it is the rhythm that originates in the sinus node

Question 22

what is the heart rate like in regards to normal sinus rhythm?

Answer 22

the rate is generally regular but will vary depending on autonomic inputs into the sinus node

Question 23

what does sinus rhythm mean?

Answer 23

it means a normal heart beat, both with respect to the heart rate and rhythm

Question 24

what is normal heart rate?

Answer 24

a heart rate that will fall between 60 and 100 beats per minute

Question 25

define normal sinus tachycardia

Answer 25

a sinus rhythm with an elevated rate of impulses

Question 26

what is normal sinus tachycardia defined as?

Answer 26

a heart rate greater than 100 beats per minute in an average adult

Question 27

define normal sinus bradycardia

Answer 27

sinus rhythm with a rate that is lower than normal

Question 28

what is normal sinus bradycardia generally defined as ?

Answer 28

it is generally defined to be a heart rate of under 60 beats per minute