Week 2 ECG

Question 1

What is sinus tachycardia? Describe the ECG

Answer 1

Regular fast HR
Same distance between each part of the wave. >100bpm.

Question 2

What is sinus bradycardia? Describe the ECG

Answer 2

Regular slow HR <60bpm.
Same distance between each wave just not as many per second.

Question 3

Describe sinus arrhythmia? What can cause it?

Answer 3

2 fast, one slow heartbeat = regular, not normal.
Can be due to breathing, breathing in increases HR, breathing out decreases HR.
Regularly irregular pattern.

Question 4

What are premature ventricular contractions (PVCs)?

Answer 4

Extra or missed beats caused by a group of cells in the ventricles that cause an early beat.
They don’t normally require investigation. May cause palpitations and a sense of the heart “skipping a beat”.

Question 5

What is a unifocal PVC?

Answer 5

When the extra beats both looks the same.
The heart is generating 2 extra beats from the same place - not to worry about.
Can be caused by too much caffeine.

Question 6

what are Multifocal PVCs?

Answer 6

Multiple extra beats that look different.
More concerning.
Coming from different places to each other.

Question 7

What is bigeminy?

Answer 7

Every other beat is an extra one.

Question 8

What is trigeminy?

Answer 8

Every third beat is an extra one.

Question 9

What does more than 3 PVCs in a run indicate?
What does the ECG look like?

Answer 9

Ventricular tachycardia (non-sustained) = VT.
Normal ECG beats followed by larger QRS complex - ventricular contractions.

Question 10

What is the issue with sustained VT?

Answer 10

It is ventricular fibrillation (VF).
Does not allow the ventricles to fill so can’t maintain cardiac output.

Question 11

What is atrial fibrillation? How can you identify it?

Answer 11

Rapid and chaotic depolarisation within the atria.
No P wave on the ECG.
Increases risk of thrombosis/embolism (blood clot) - causes 20% of all strokes.

Question 12

How to identify wolf parkinson white syndrome? What is it?

Answer 12

Very short PR interval (0.08s) - speeds everything up.
The electrical impulse bypasses the AV node.
Pre-excitation syndrome.

Question 13

How to identify atrioventricular blocks
How are they sometimes treated?

Answer 13

Longer PR intervals - slows everything down.
if 2nd or 3rd degree block may be fitted with a pacemaker.

Question 14

Right bundle branch block
How to identify?
Issues?
What happens

Answer 14

M shape in the QRS of V1 and W in V6 - MARROW
Fairly common in athletes, doesn’t really cause any major issues or symptoms.
Signal affected goes to the right ventricles from the bundle of His

Question 15

Left bundle branch block
How to identify?
Issues?
What happens?

Answer 15

Tall R waves in V5-V6, deep S waves in V1-3.
W in V1, M in V6 QRS - WILLIAM
Do not exercise if you have this, if blockage is in left ventricle oxygen won’t be getting to the body - danger for exercise.
RV depolarises normally and first via RBB, delayed activation of LV as must be depolarised by the RBB with depolarisation from R to L.

Question 16

Left ventricular hypertrophy
When to expect?
Issues?
What does the ECG look like?

Answer 16

Athletes, thin chest walls (not much space between heart and electrode makes voltage seem higher than it is). Uncontrolled, long lasting hypertension and aortic stenosis (narrowing of heart valve) - left ventricle has to thicken to pump blood as at higher pressure.
Often considered normal in athletes.
Thickened walls leads to prolonged depolarisation (R) and delayed repolarisation (ST and T in lateral leads).

Question 17

How to identify myocardial ischemia?
What suggests it is a blockage of the left main coronary artery?

Answer 17

ST depression >1mm. Leads II, III and V4
T wave inversion (flattening) can be seen but not always.

Widespread ST depression across multiple leads.

Question 18

How to identify myocardial infarction?

Answer 18

ST elevation (STEMI = ST elevated MI).

Question 19

When is medical clearance needed?

Answer 19

Known disease but no symptoms.
Any signs or symptoms suggestive of disease.

If cleared they can progress from light to moderate exercise.

Question 20

Who should be supervising different patients.

Answer 20

Low risk - no-one, safe to exercise alone.
Medium risk - a HCP with exercise testing experience
High risk - a HCP with exercise testing experience, doctor must be immediately available (ILS trained for administration of drugs if CV event).

Question 21

What are some contraindications to exercise?

Answer 21

Unstable anything e.g. angina, diabetes, arrhythmia, tachycardia.
Resting SBP> 180/200
Resting DBP > 100/110
Symptomatic Hypotension
Acute infections
Heart disease

Question 22

What is phase 0?

Answer 22

Rapid depolarisation
Na+ channels open for rapid influx of Na.

Question 23

Phase 1

Answer 23

Rapid depolarisation
Na channels close/become inactivated - no Na influx.
K+ channels open for brief K+ influx then close rapidly.

Question 24

Phase 2

Answer 24

Plateau (longest phase)
Influx of Ca2+ - released from sarcoplasmic reticulum to initiate contraction
K+ efflux (causes plateau)

Question 25

Phase 3

Answer 25

Rapid repolarisation
Ca2+ channels closed (no more contraction)
K+ channels remain open until restores the membrane potential to resting value

Question 26

Phase 4

Answer 26

Resting potential
Stable at -90mV in normal working myocardial cells
Na closed
Ca closed
K+ stay open until the next action potential arrives and Phase 0 starts again

Question 27

Suggest some abnormal ECG findings that would require further investigation

Answer 27

T wave inversion
ST segment depression
Pathologic Q waves
Complete LBBB
QRS>140ms duration
Ventricular pre-excitation
Prolonged QT interval
Sinus bradycardia <30bpm.
Atrial tachycardia
Ventricular arrhythmias
Atrial enlargements
Complete RBBB
Axis deviations

Question 28

What are some causes of sudden cardiac death that can be identified using ECG?

Answer 28

Hypertrophic cardiomyopathy
Wolf-Parkinson-White syndrome
Right ventricular outflow tachycardia
Marfan syndrom
Congenital long QT syndrome
Electrolyte disturbances (hypokalemia or hyperkalemia)

Question 29

Normal ECG findings that do not require any further investigation

Answer 29

Increased QRS voltage for LVH or RVH
Incomplete RBBB
T wave inversion < 16 years
Sinus bradycardia or arrhythmias
ST elevation and T wave inversion in black athletes.