Week 10 - ECG

Question 1

what is the P wave

Answer 1

Atrial contraction. (this is only a holding area for blood it is then sent to the ventricles requiring a small contraction. electrical activity is proportional to muscle activity)

Question 2

What is the QRS complex

Answer 2

Ventricular contraction

Question 3

WHat is the T wave

Answer 3

Ventricular repolarisation. Return of the ventricular mass to its resting electrical state

Question 4

Where is atrial repolarisation

Answer 4

this does occur but it is completel swamped in the QRS. AKa the QRS wave is so big it hides the atrial repolarisation

Question 5

How does the elctrical current travel through the heart?

Answer 5

1. starts at the right atrium in the SA node
2. depolarisation spreads across atrium
3. electrical discharge spreads to the ventricles via the AV node
4. from ventricles electrical discharge goes through the bundle of his in he interventricular spetum to the left bundle branch
5. then spreads to the purkinge fibres

Question 6

Why is there a delay between the atrial and the ventricles?

Answer 6

allows time for blood to move from atria to ventricles ready to be pumped

Question 7

What sets the rhythm of the heart

Answer 7

SA node sets the intrinisc rhythm

Question 8

Where are the pacemakers in the heart?

Answer 8

SA node in the atrium.  Highest frequency discharge
Av node at AV junction (40-60bpm)
Purkinje fibres (20-40bpm)

Question 9

On an ECG what determines the shape of the QRS (up or down)

Answer 9

If wave of depolarisation is towards a lead then the deflection on the ECG will be upward

Question 10

How do you calculate time the ECG trace

Answer 10

each large square is 0.2 seconds

each small squares is 0.04 seconds

Question 11

What is the normal duraction of the QRS complex

Answer 11

less than 0.12 seconds (3 small squares). THis is the time taken for excitation to spread through the ventricles

Question 12

What is the normal duration of the PR interval

Answer 12

0.12-0.2 seconds (3-5 small squares)

Question 13

What is the PR interval

Answer 13

TIme take for the excitation to spread from the SAM node through the atrial muscles and the AV node down to the bundle of his and into the ventricular muscle

Question 14

What are the characteristics of normal sinus rhythm

Answer 14

HR: 60-100bpm
Rhythm: regular
P wave: before each QRS
PR interval: 0.12-0.2 seconds
QRS < 0.12 seconds

Question 15

What is ventricular ectopic beats

Answer 15

ventricular extrasystoles an example of abnormal timing
Extra beats but not arising from the SA node
depolarisation mixing with reploarisation

Question 16

WHat is Prolongation of PR interval indicitive of

Answer 16

First degree heart block

Question 17

WHat is first degree heart block

Answer 17

Prolongation of the PR interval. Longer than the 0.12-0.2 that is normal.
Is still coming supraventricularly as QRS is still normal

Question 18

If you are experiencing a heart issue on the ECG, the QRS is abnormal but the P was is fine, where is it coming from

Answer 18

Ventricularly as apposed to suprventricularly

Question 19

What is second degree heart block

And how does this look on an ECG

Answer 19

excitation fails to pass through the AV node or the bundle of his
On an ECG: P wave but no QRS complex

Question 20

There are three variations of second degree heart block. What is the first (Mobitz type 2)

Answer 20

Most beats are conducted with regular PR interval but occasionally there is an atrial contraction without a subsequent COntraction

Question 21

Second type of second degree heart block ( Wenkebatch phenomena

Answer 21

Progressive lengthing of the PR interval and then a failure to conduct of an atrial beat followed by a shorter / normal PR interval and a repitition of the cycle

Question 22

Variation three of 2nd degree heart block

Answer 22

There may be alternate conducted and non conduction atrial beat. THe ration of P wave to ventricular complexes can vary E.g 2:1 or 3:2

Question 23

What is third degree Heat Block

Answer 23

COmplete block
atrial contraction by no beats conducted in the ventricles
Atria and ventrical contracting independently

Question 24

WHat is bundle branch block

Answer 24

Widening of the ventricular complex as depolarisation hasn’t spread via bundle branches

Question 25

What type of rhythm has wide QRS complexes

Answer 25

Ventricular rhythms

Question 26

What does narrow QRS complexes mean

Answer 26

Its a supraventricular rhythm

Question 27

WHat are the 4 classifications of abnormal cardiac rythms

Answer 27

Cardiac Slowing ( escape beats and Bradycardia)
Early single beats
Sustained and fast rhythm (Tachycardia)
Total disorganisation (atrial or ventricular firing or fibrilation)

Question 28

What are early single beats

Answer 28

Ventricular ectopic beats (r occurs on the T

Or Premature ventricular contraction (PVCs)

Question 29

Atrial fibrilation

Answer 29

QRS is still there but there are many P waves in the middle

Question 30

List some clinical symptoms and signs showing abnormal ECGS

Answer 30

LOC _ dizziness, near syncope and syncope
Hypotentions
Palpitation
Abnormilites of the pulse
chest pain
SOB

Question 31

Should the ST segment be lvel

Answer 31

Yes it should be. And should be at sam level as between T and P

Question 32

What are the types of tachycardia

Answer 32

1. supraventricular - Atrial flutter

2. ventricular - ventricular tachcardia

Question 33

What does a horizontal ST segment indicitive of

Answer 33

Sign of ongoing ischemia

Can be normal for exercise with an increase in HR

Question 34

What happens to the ST segment when having an acute myocardial injury

Answer 34

Elevation of the ST segment