ECGs Flashcards
In an anterior MI, what is the most likely occluded artery and in what leads does this cause ST elevation in?
Left Anterior Descending
V2-V5
In an inferior MI, what is the most likely occluded artery and what leads show ST elevation?
Right Coronary Artery
II, III aVF
In a lateral MI, what is the most likely occluded artery and what leads show ST elevation?
Left Circumflex Artery
I, aVL
In a posterior MI, what is the most likely occluded artery and what leads show ST elevation?
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
In an anterolateral MI, what is the most likely affected artery and what leads show ST elevation?
Left Anterior Descending
V4-V6, I, aVL
If someone is in complete heart block, what will show on an ECG?
JVP Cannon A waves
What artery supplies the SA and AV node with blood?
Right coronary artery
The right coronary artery also supplies the septum of the heart with blood
How do you work out the rate of an ECG?
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
What is the way to remember left axis deviation and right axis deviation?
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
What can cause left axis deviation?
Inferior MI
WPW
Left ventricular hypertrophy
Left anterior hemiblock
What can cause right axis deviation?
Right ventricular hypertrophy
PE
Anterolateral MI
WPW
What are Q and S waves?
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
What do broad QRS complexes represent?
What is the normal duration of a QRS complex?
Ventricular conduction defects e.g. Bundle branch block, metabolic disturbance
The normal duration is <0.12 seconds
In what leads would T waves have to be inverted in to be abnormal?
If T waves are inverted in I, II and V4-V6 this is abnormal
What are J waves and what do these represent?
The J wave is the point where the S wave finishes and ST segment starts
They are seen in hypothermia, hypercalcaemia and SAH.
What are the causes of sinus bradycardia?
Physical fitness Drugs (beta blockers, digoxin, amiodarone) Sick sinus syndrome Hypothyroidism, hypothermia Raised ICP
List some common causes of AF
Thyrotoxicosis Hypertension Obesity Heart failure Alcohol
What happens in first degree heart block?
If R is far from P, you have a first degree
The PR interval is prolonged and fixed
What happens in second degree heart block?
Mobitz Type 1 (Wenkebach)
The PR interval becomes longer and longer until a QRS complex is dropped
What happens in third degree heart block?
Mobitz Type II
QRS complexes are dropped without any warning
Can progress to complete heart block so it is worrying
What happens in complete heart block?
What can cause complete heart block?
No correlation between P waves and QRS complexes
Inferior MI, aortic valve calcification, digoxin toxicity
What pathologies cause ST elevation?
acute MI (STEMI)
Acute pericarditis
Left ventricular aneurysm
What pathologies cause ST depression?
Digoxin toxicity
NSTEMI
Acute posterior MI
What are the ECG changes that you see in a MI?
Within hours, T waves becomes peaked and ST segments begin to rise
Within 24hours, the T waves invert
Pathological Q waves may form
What are the ECG changes that you see in PE?
Sinus tachycardia
RBBB
Right axis deviation
Rarely, the S1Q3T3 pattern
What ECG changes would you see with hyper and hypokalaemia?
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)
What does a LBBB look like on an ECG?
WiLLiaM
W pattern in V1 and a M pattern in V6
Widened QRS complex
Dominant S in V1
What are the causes of LBBB?
IHD
HTN
Cardiomyopathy
Aortic stenosis
How does RBBB present on an ECG?
M wave in V1 (RSR pattern), W wave in V6
Widened QRS complex
What are the causes of RBBB?
Cor pulmonale
Right ventricular hypertrophy
PE
MI
How does digoxin toxicity present on an ECG?
Down sloping ST depression
Inverted T waves
Short QT interval
What are the causes of ST depression?
Ischaemia
Digoxin
Hypokalaemia
What may a short PR interval point towards?
WPW syndrome
What is a mnemonic that can be used to remember the reciprocal changes that occur in the ECG leads?
PAILS Posterior Anterior Inferior Lateral Septal
ST elevation in one lead causes reciprocal changes in the one below
What are the normal variants on ECGs that athletes may have?
Sinus bradycardia
Wenkebach phenomenon
First degree AV block
What does bifascicular block look like on an ECG?
Combination of RBBB with left anterior or posterior hemiblock (e.g. LAD)
What ECG findings will you see in hypothermia?
Bradycardia
J wave
First degree heart block
Long QT interval
