Electrocardiography

Question 1

what is ECG useful in diagnosing?

Answer 1

1. Conduction abnormalities
2. Structural abnormalities
3. Perfusion abnormalities

Question 2

what are the benefits of an ECG?

Answer 2

• Relatively cheap and easy to undertake
• Reproducible between people and centres
• Quick turn around on results/report

Question 3

what is a vector?

Answer 3

• Quantity that has both magnitude and direction
• Represented by arrow in net direction of movement, where size represents magnitude

Question 4

what are the different elements of an ECG?

Answer 4

Question 5

draw a normal cardic cycle on an ECG and the changes in pressure in aorta, atrium and ventricle throughout.

Answer 5

Question 6

what are the different aspects of the heart involved in the cardiac cycle?

Answer 6

Question 7

where do the electrodes go on an ECG?

Answer 7

Question 8

what aspect do each lead view on the heart

Answer 8

Question 9

on an ECG which section corresponds to which view of the heart?

Answer 9

Question 10

what are the different cardiac vectors?

Answer 10

Question 11

what time does each square represent on an ECG?

Answer 11

Question 12

which artery is measured in each section of an ECG?

Answer 12

lateral =Left circumflex artery

inferior and anterior= right coronary artery

septal= left anterior descending artery

Question 13

how do you calculate the different intervals in an ECG:

Answer 13

Question 14

what is a normal R-R interval?

Answer 14

0.6-1.2s

Question 15

what is a normal p wave?

Answer 15

80ms

Question 16

what is a normal P-R interval?

Answer 16

120-200ms

Question 17

what is a normal QRS duration?

Answer 17

<120ms

Question 18

what is a normal QT interval?

Answer 18

<420ms

Question 19

what is a normal T wave duration?

Answer 19

160ms

Question 20

what is a normal heart rate?

Answer 20

60-100bpm

Question 21

what information is required to calculate a QRS axis?

Answer 21

requires an augmented lead perpendicular to it

Question 22

what is an augmented lead?

Answer 22

uses one fixed lead and one which is half the distance between another

Question 23

what should a normal cardiac axis be between?

Answer 23

-30 and +90

Question 24

how do you calculate the cardiac axis?

Answer 24

cardiac axis is reported relative to 0 degrees

so if using lead II which is at 60 deg then subtract answer from 60 deg

Question 25

what is the sinus rhythm generated by?

Answer 25

sinoatrial node

Question 26

how do you calculate heart rate?

Answer 26

300/ number of big squares S-S

Question 27

what is this rhythm and features?

Answer 27

**Sinus Rhythm:** * Each p-wave is followed by QRS wave (1:1) * Rate is regular (even R-R intervals) and normal

Question 28

what is this rhythm and its features?

Answer 28

**Sinus Bradycardia:** * Each p-wave followed by QRS wave (1:1) * Rate regular (even R-R intervals) and SLOW Can be healthy (caused by medication or vagal stimulation)

Question 29

what is this rhythm and its features?

Answer 29

**Sinus tachycardia:** * Each p-wave followed by QRS wave (1:1) * Rate is regular and FAST * Often physiological response i.e. secondary (medication, excitation)

Question 30

what is this rhythm and its features?

Answer 30

**Sinus arrhythmia:** * Each p-wave followed by QRS wave * Rate IRREGULAR and normal-ish * R-R interval varies within breathing cycle

Question 31

what is this rhythm and its features?

Answer 31

**Atrial fibrillation:** * Oscillating baseline- atria contracting asynchronously * Rhythm can be IRREGULAR and may be SLOW * Turbulent flow pattern increases clot risk * Atria not essential for cardiac cycle

Question 32

what is this wave and its features?

Answer 32

**Atrial Flutter:** * Regular saw-toothed pattern in baseline (II, III and aVF) * Atrial to ventricular beats at 2:1 ratio, 3:1 ratio or higher * Saw toothed not always visible in all leads

Question 33

what is this wave and its features?

Answer 33

**First degree heart block:** * Prolonged PR segment/ interval caused by slower AV conduction * Regular rhythm (1:1 ratio P-wave to QRS) * Most benign heart block but progressive disease or aging)

Question 34

what is this wave and its features?

Answer 34

**Second degree Heart Block: (Mobitz I)** * Gradual prolongation of the PR interval until a beat skipped * Most P-waves followed by QRS but some p-waves are not * Regularly irregular, caused by diseased AV node * Also called Wencheback

Question 35

what is this wave and its features?

Answer 35

**Second degree heart block (Mobitz II)** * P-waves regular, but only some followed by QRS * No P-R prolongation * Regularly irregular ratio successes to failures or random * Can rapidly deteriorate into 3^rd degree heart block * Usually dropped in bundle of His or bundle branches

Question 36

what is this wave and its features?

Answer 36

**Third degree (complete) heart block)** * P-waves regular, QRS regular but independent of each other * P-waves can be hidden within bigger vectors * Non-sinus rhythm * Pumping pf ventricles being determined by ventricles themselves rather than AV node

Question 37

what is this wave and its features?

Answer 37

**Ventricular tachycardia:** * P-waves hidden- dissociated atrial rhythm * Rate regular and fast * High risk deteriorating into fibrillation (cardiac arrest) * Shockable rhythm (defibrillators widely available)

Question 38

what is this wave and its features?

Answer 38

**Ventricular fibrillation:** * Heart rate irregular and 250bpm or above * Heart unable to generate an output * Shockable rhythm

Question 39

what is this wave and its features?

Answer 39

**ST elevation:** * P-waves visible and always followed by QRS * Rhythm is regular and rate is normal (85bpm) * ST segment is elevated \>2mm above isoelectric line * Caused by infarction (tissue death caused by hypoperfusion)

Question 40

what is this wave and its features?

Answer 40

**ST depression:** * P waves visible and always followed by QRS * Rhythm regular and rate normal (95bpm) * ST segment is depressed \>2mm below isoelectric line * Caused by myocardial ischemia (coronary insufficiency)