ECGs

Question 1

In an anterior MI, what is the most likely occluded artery and in what leads does this cause ST elevation in?

Answer 1

Left Anterior Descending

V2-V5

Question 2

In an inferior MI, what is the most likely occluded artery and what leads show ST elevation?

Answer 2

Right Coronary Artery

II, III aVF

Question 3

In a lateral MI, what is the most likely occluded artery and what leads show ST elevation?

Answer 3

Left Circumflex Artery

I, aVL

Question 4

In a posterior MI, what is the most likely occluded artery and what leads show ST elevation?

Answer 4

Right Coronary Artery or Left Circumflex
No leads show ST elevation

Reciprocal changes occur: in VI-V3, prominent R waves, flat ST depression, and T wave inversion may be seen

Question 5

In an anterolateral MI, what is the most likely affected artery and what leads show ST elevation?

Answer 5

Left Anterior Descending

V4-V6, I, aVL

Question 6

If someone is in complete heart block, what will show on an ECG?

Answer 6

JVP Cannon A waves

Question 7

What artery supplies the SA and AV node with blood?

Answer 7

Right coronary artery

The right coronary artery also supplies the septum of the heart with blood

Question 8

How do you work out the rate of an ECG?

Answer 8

Divide 300 by the number of big squares in between two R waves

Each big square represents 0.2, each small square represents 0.04

Question 9

What is the way to remember left axis deviation and right axis deviation?

Answer 9

LAD: lovers leaving. The QRS complexes in I and II point away from each other.

RAD: lovers returning. The QRS complexes in I and III point towards each other

Question 10

What can cause left axis deviation?

Answer 10

Inferior MI
WPW
Left ventricular hypertrophy
Left anterior hemiblock

Question 11

What can cause right axis deviation?

Answer 11

Right ventricular hypertrophy
PE
Anterolateral MI
WPW

Question 12

What are Q and S waves?

Answer 12

In a QRS complex, if the first deflection from the isoelectric line is negative, it is a Q wave
Any negative deflection after R is an S wave

Question 13

What do broad QRS complexes represent?

What is the normal duration of a QRS complex?

Answer 13

Ventricular conduction defects e.g. Bundle branch block, metabolic disturbance

The normal duration is <0.12 seconds

Question 14

In what leads would T waves have to be inverted in to be abnormal?

Answer 14

If T waves are inverted in I, II and V4-V6 this is abnormal

Question 15

What are J waves and what do these represent?

Answer 15

The J wave is the point where the S wave finishes and ST segment starts

They are seen in hypothermia, hypercalcaemia and SAH.

Question 16

What are the causes of sinus bradycardia?

Answer 16

Physical fitness
Drugs (beta blockers, digoxin, amiodarone)
Sick sinus syndrome
Hypothyroidism, hypothermia
Raised ICP

Question 17

List some common causes of AF

Answer 17

Thyrotoxicosis
Hypertension
Obesity 
Heart failure 
Alcohol

Question 18

What happens in first degree heart block?

Answer 18

If R is far from P, you have a first degree

The PR interval is prolonged and fixed

Question 19

What happens in second degree heart block?

Answer 19

Mobitz Type 1 (Wenkebach)

The PR interval becomes longer and longer until a QRS complex is dropped

Question 20

What happens in third degree heart block?

Answer 20

Mobitz Type II

QRS complexes are dropped without any warning
Can progress to complete heart block so it is worrying

Question 21

What happens in complete heart block?

What can cause complete heart block?

Answer 21

No correlation between P waves and QRS complexes

Inferior MI, aortic valve calcification, digoxin toxicity

Question 22

What pathologies cause ST elevation?

Answer 22

acute MI (STEMI)
Acute pericarditis
Left ventricular aneurysm

Question 23

What pathologies cause ST depression?

Answer 23

Digoxin toxicity
NSTEMI
Acute posterior MI

Question 24

What are the ECG changes that you see in a MI?

Answer 24

Within hours, T waves becomes peaked and ST segments begin to rise
Within 24hours, the T waves invert
Pathological Q waves may form

Question 25

What are the ECG changes that you see in PE?

Answer 25

Sinus tachycardia RBBB Right axis deviation Rarely, the S1Q3T3 pattern

Question 26

What ECG changes would you see with hyper and hypokalaemia?

Answer 26

Hyperkalaemia: tall tented T waves, widened QRS complexes, absent P waves Hypokalaemia: in hypokalaemia U have no Pot and no T, but a long PR and a long QT (in order of most common to least common)

Question 27

What does a LBBB look like on an ECG?

Answer 27

WiLLiaM W pattern in V1 and a M pattern in V6 Widened QRS complex Dominant S in V1

Question 28

What are the causes of LBBB?

Answer 28

IHD HTN Cardiomyopathy Aortic stenosis

Question 29

How does RBBB present on an ECG?

Answer 29

M wave in V1 (RSR pattern), W wave in V6 | Widened QRS complex

Question 30

What are the causes of RBBB?

Answer 30

Cor pulmonale Right ventricular hypertrophy PE MI

Question 31

How does digoxin toxicity present on an ECG?

Answer 31

Down sloping ST depression Inverted T waves Short QT interval

Question 32

What are the causes of ST depression?

Answer 32

Ischaemia Digoxin Hypokalaemia

Question 33

What may a short PR interval point towards?

Answer 33

WPW syndrome

Question 34

What is a mnemonic that can be used to remember the reciprocal changes that occur in the ECG leads?

Answer 34

``` PAILS Posterior Anterior Inferior Lateral Septal ``` ST elevation in one lead causes reciprocal changes in the one below

Question 35

What are the normal variants on ECGs that athletes may have?

Answer 35

Sinus bradycardia Wenkebach phenomenon First degree AV block

Question 36

What does bifascicular block look like on an ECG?

Answer 36

Combination of RBBB with left anterior or posterior hemiblock (e.g. LAD)

Question 37

What ECG findings will you see in hypothermia?

Answer 37

Bradycardia J wave First degree heart block Long QT interval