ECGs

Question 1

Where do you place V1 and V2?

Answer 1

4th ICS, on left and right sternal edges

Question 2

Where do you place V4?

Answer 2

5th ICS, mid-clavicular line

Question 3

What are the 10 rules of ECGs?

Answer 3

1. PR interval ≈ 3-5 mini squares
2. QRS < 3 mini squares
3. QRS predominantly upright in I & II
4. QRS and T waves tend to have same directions in limb leads
5. All waves negative in aVR
6. R wave grows to at least V4 and S wave grows to at least V3 and disappears by V6
7. ST segment starts isoelectric except in V1 and V2
8. P waves upright in I, II and V2-6
9. No or very small Q wave (<1 small square) in I, II and V2-6
10. T wave upright in I, II and V2-6

Question 4

What can a prolonged PR interval indicate?

Answer 4

Atrioventricular delay (AV block or heart block)

Question 5

What is first degree heart block?

Answer 5

Conduction block between the SA and AV node

Question 6

What is type 1 second degree heart block?

Answer 6

Conduction block within the AV node

Question 7

What are the ECG signs for a posterior MI?

Answer 7

ST depression in leads V1-V4

Question 8

How do you use an ECG to diagnose a posterior MI?

Answer 8

Remove leads V4-V6 and place then on the left side of the patients back, under the scapula, these leads become V7, V8 and V9, this will show elevation in this area.

Question 9

How do you use an ECG to diagnose right ventricular infarction?

Answer 9

Remove V4 and reapply on patient’s right side becoming V4 R

Question 10

What is normal QRS axis range?

Answer 10

-30° to +90°

Question 11

What can ST elevation in leads II, III and aVF signify?

Answer 11

Inferior STEMI

Question 12

What can ST elevation in leads I, aVL, V5 and V6 signify?

Answer 12

Lateral STEMI

Question 13

What can ST elevation in leads V1-V4 signify?

Answer 13

Anterior STEMI

Question 14

What can ST elevation in leads V1 and V2 signify?

Answer 14

Septal STEMI

Question 15

What can ST depression in leads V1-V3 signify?

Answer 15

Posterior STEMI

Question 16

What are the ECG signs for a right ventricular infarction?

Answer 16

ST elevation in V1
ST elevation in V1 and ST depression in V2 (highly specific for RV infarction)
Isoelectric ST segment in V1 with marked ST depression in V2
ST elevation in III > II

Question 17

What occurs during the P wave?

Answer 17

Depolarisation of the atria in response to the SA node triggering.

Question 18

What occurs during the PR Interval?

Answer 18

Atria complete depolarisation and contract filling the ventricles, AV node delayed.

Question 19

What occurs during the QRS complex?

Answer 19

Depolarisation of ventricles triggers main pumping contractions.

Question 20

What occurs during the ST segment?

Answer 20

Ventricles contract. Line should be flat.

Question 21

What occurs during the T wave?

Answer 21

Ventricular repolarisation.

Question 22

What are ECG signs of pericarditis?

Answer 22

Global ST elevation
PR elevation in aVR (thumbprint sign)
PR depression
Diffuse concave ST elevation

Question 23

What are the ECG features of a RBBB?

Answer 23

Broad QRS > 120 ms
RSR’ pattern in V1-3 (‘M-shaped’ QRS complex)
Wide, slurred S wave in the lateral leads (I, aVL, V5-6)

Question 24

What are the ECG features of a LBBB?

Answer 24

QRS duration of> 120 ms
Broad monophasic R wave in lateral leads (I, aVL, V5-V6)
Dominant S wave in V1
Absence of Q waves inlateral leads (I, V5-V6; small Q waves are still allowed in aVL)

Prolonged R wave peak time > 60ms inleftprecordialleads (V5-6)

Question 25

What are the ECG signs of Bragada syndrome?

Answer 25

RSR terminates into an inverted T-wave with ST elevation

Question 26

What are the ECG changes of Wolf-Parkinson-White syndrome?

Answer 26

Short PR interval Delta wave (sloped R) Prolonged QRS >110ms ST Segment and T wave discordant changes

Question 27

What are the ECG signs of Hypertrophic Cardiomyopathy (HCM)?

Answer 27

Narrow, dagger like Q waves in lateral leads High voltages

Question 28

What are the ECG findings of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)?

Answer 28

Epsilon wave (30% of patients and most specific finding) T wave inversion in V1 – V3 (85% of patients) Prolonged S-wave upstroke of 55ms in V1-V3 Localised QRS widening of 110ms in V1-V3

Question 29

What is considered a long QT?

Answer 29

>440ms in men or >460ms in women More than 500ms - high risk of developing fatal arrhythmia

Question 30

What can cause long QT?

Answer 30

Hypomagnesaemia Hypokalaemia Hypocalcaemia Secondary to alcohol dependency – ECGs important in withdrawal seizures. Medications – antibiotics, anti-emetics, anti-arrhythmics, anti-depressants/ anti-psychotics

Question 31

What is QTc?

Answer 31

QT corrected - calculated with the heartrate accounted for

Question 32

What are the red flags for syncope?

Answer 32

Exertional syncope Incontinence Advanced age Tongue biting Headache, chest pain, palpitations or SOB Prolonged seizure like movements Absence of provoking factor/ prodrome Prolonged recovery or confusion Cardiovascular disease Neurological deficit Occurs in supine position Injury from fall

Question 33

How should you manage LBBB patients with a clinical suspicion of MI?

Answer 33

Patients with a clinical suspicion of ongoing myocardial ischaemia and LBBB should be managed in a way similar to STEMI patients, regardless of whether the LBBB is previously known.

Question 34

Why can Hypertrophic Cardiomyopathy (HCM) commonly be misdiagnosed with an ECG as an old lateral MI?

Answer 34

Old lateral MIs can show with deep Q waves in lateral leads. The dagger like sharp Q waves of HCM can be incorrectly diagnosed as those of an old lateral MI.

Question 35

What is the main difference in Brugada and RBBB ECG presentation?

Answer 35

Brugada complexes with have bi