ECG & rhythm disorders

Question 1

What can be spotted on an ECG?

Answer 1

Conduction Abnormalities
Structural abnormalities
Perfusion abnormalities

Question 2

What do upward and downward deflections signify?

Answer 2

Upward deflections are towards the +ve electrode

Downward deflections are towards the -ve electrode

Question 3

What does the isoelectric line represent?

Answer 3

no net change in voltage, vectors are perpendicular to the lead.

Question 4

What do steepness and width of the line denote?

Answer 4

Steepness - velocity

Width - duration

Question 5

What does the P wave represent?

Answer 5

The electrical signal that stimulates contraction of the atria (atrial systole).

Question 6

What does the QRS complex represent?

Answer 6

The electrical signal that stimulates contraction of the ventricles (ventricular systole)

Question 7

What does the T wave represent?

Answer 7

The electrical signal that signifies relaxation of the ventricles.

Ventricular repolarisation

Question 8

What does the Q wave represent?

Answer 8

Septal depolarisation

Question 9

What does the R wave represent?

Answer 9

Ventricular depolarisation

Question 10

What does the S wave represent?

Answer 10

Late ventricular depolarisation

Question 11

Where do you place the first 3 leads?

Answer 11

Lead 1 - right arm to Left arm
Lead 2 - right arm to Left Leg
Lead 3 - Left arm to Left Leg
number of L’s represents the lead number

Question 12

Where do you place V1?

Answer 12

Right sternal border in the 4th intercostal place

Question 13

Where do you place V2?

Answer 13

Left sternal border in the 4th intercostal place

Question 14

Where do you place V3?

Answer 14

Halfway between V2 & V4

Question 15

Where do you place V4?

Answer 15

Mid clavicular line in the 5th intercostal place

Question 16

Where do you place V5?

Answer 16

Anterior axillary line at the level of V4

Question 17

Where do you place V6?

Answer 17

Mid axillary line at the level of V4

Question 18

How many seconds does a square on an ECG represent?

Answer 18

0.04 seconds

Question 19

What are the 5 steps of ECG interpretation?

Answer 19

Rate & Rhythm
P wave & PR interval
QRS duration
QRS axis
ST segment

Question 20

What is the procedure for ECG implementation?

Answer 20

Is it the correct recording
Review the signal and quality of the leads
Verify voltage and paper speed
Review the patient background if available

Question 21

What does the Cardiac axis show?

Answer 21

Cardiac axis gives the net vector of the R-wave, which is usually the largest electrical event as it is the biggest amount of muscle – normal range is -30 to +90 degrees
NEED TO KNOW HOW TO WORK IT OUT

Question 22

What is normal sinus rhythm?

Answer 22

Each P wave is followed by a QRS wave 1:1

Rate is regular and normal 60-100

Question 23

What is sinus bradycardia?

Answer 23

Each P wave is followed by a QRS wave 1:1

Rate is regular and slow e.g 56 bpm

Question 24

What is sinus tachycardia

Answer 24

Each P wave is followed by a QRS wave 1:1

Rate is regular and fast e.g 110 bpm

Question 25

What is sinus arrhythmia?

Answer 25

Each P wave followed by QRS wave
Rate in irregular and relatively normal
R-R interval varies with breathing cycle due to vagal nerve stimulation which reduces heart rate. arrhythmia is normal and probably present in half of us

Question 26

What is atrial fibrillation?

Answer 26

Oscillating baseline - atria are contracting asynchronously
Rhythm can be irregular and rate may be slow
Turbulent flow pattern increases clot risk
Atria not essential for cardiac cycle

Question 27

What is Atrial flutter?

Answer 27

Regular saw tooth pattern in baseline
Atrial to ventricular beats at a 2:1, 3:1 ratio or higher
Saw tooth not always visible in all leads

Question 28

What are the characteristic’s of first degree heart block?

Answer 28

Prolonged PR segment/interval caused by slower AV conduction.
Regular rhythm
Most benign heart block but is a progressive disease of ageing.

Question 29

What is second degree heart block Mobitz type 1?

Answer 29

Gradual lengthening of the PR interval until a beat is skipped
Most P waves followed by QRS; but some P waves are not.
Regularly irregular; Caused by a diseased AV node
Also known as Wenckebach

Question 30

What is second degree heart block Mobitz type 2?

Answer 30

P waves are regular, but only some are followed by QRS.
No P-R prolongation
Regularly irregular, 2:1 successes to failures or random
Can rapidly deteriorate into third degree heart block

Question 31

What is third degree heart block?

Answer 31

P waves are regular, QRS are regular, but no relationship.
P waves can be hidden within bigger vectors.
Non-sinus rhythm - back up pacemaker in action.

Question 32

What is ventricular tachycardia?

Answer 32

P waves hidden - dissociated atrial rhythm
Rate is regular and fast 100-200
At high risk of deteriorating into fibrillation (cardiac arrest)
Shockable rhythm - defibrillators widely available

Question 33

What is ventricular fibrillation?

Answer 33

Heart rate irregular and 250 bpm or above
Heart unable to generate an output
Shockable rhythm

Question 34

What is ST elevation?

Answer 34

P waves visible and always followed by QRS
Rhythm is regular and rate is normal
ST segment elevated >2mm above the isoelectric line
Caused by infarction - tissue death caused by hypoperfusion

Question 35

What is ST depression?

Answer 35

P waves visible and always followed by QRS
Rhythm is regular and rate is normal
ST segment is depressed >2mm below the isoelectric line
Caused by myocardial ischaemia (coronary insufficiency)