Cardio week: ECG Flashcards
Where are the chest leads V1-V6 placed in an ECG
V1: 4th intercostal space RSE V2: 4th intercostal space LSE V3: between V2 & V4 V4: apex V5: L anterior axillary (same level as V4) V6: L mid-axillary (same level as V4)
Limb + chest leads:
Which look at chest in coronal/ axial plane?
Limb leads: coronal plane
Chest leads: axial plane
Where are the most common sites of infarction of the heart
Anterior and inferior aspects
Which part of the heart is supplied by the RCA?
What leads suggest a problem with the RCA?
Inferior
Leads: II, III, avF
Which part of the heart is supplied by the LAD?
What leads suggest a problem with the LAD?
Anteroseptal
Leads: V1-V4
Which part of the heart is supplied by the Cx?
What leads suggest a problem with the Cx?
Lateral
Leads: 1, aVL, V5, V6
What does the electrical axis indicate
Average direction of spread of ventricular depolarisation
Lead I/II positive/negative
Which indicates LAD/RAD?
LAD: Lead I positive, Lead II negative
RAD: Lead I negative, Lead II positive
How long & high should a normal P wave be?
length <0.11s
(2.5 small boxes)
height <2.5mm
(2.5 small boxes)
What is the significance of an absent P wave?
SA node has not fired eg in Atrial fibrillation
What might a taller P wave indicate?
Atrial hypertrophy eg in chronic pulmonary disease
How long should a normal PR interval be?
0.12-0.2s
3-5 small boxes
What happens to ECG during WPW syndrome?
Briefly explain why.
Shortened PR interval.
WPW: accessory pathway communicates between atria and ventricles, conducts electricity at much higher rate than AV node.
How long should normal QRS complex be
<0.12s
less than 3 small boxes
What stage in the cardiac cycle do the following signify
P wave QRS complex T wave U wave ST segment
P wave: atrial depolarisation
QRS complex: ventricle depolarisation
T wave: ventricle repolarisation
U wave: Purkinje fibre repolarisation
ST segment: ventricle contracting but no electricity flowing (periods between ventricular depolarisation and repolarisation)
What might tall QRS indicate?
Ventricular hypertrophy
or slim patient
What might tall T waves indicate?
- Hyperkalemia
- Very early MI
What might prominent U waves indicate?
- Hypercalcaemia
- Hypokalemia
- Digoxin toxicity
What might ST elevation indicate?
- Acute MI
- Pericarditis
- Brugada syndrome
What might ST depression indicate?
- MI at back of heart
- previous MI
- previous ischaemia
How does A Fib present on ECG
Absence of P waves
How does A flutter present on ECG
Saw tooth appearance
How does MI present on ECG
ST elevation or depression
How does V fib present on ECG
Bag of worms (chaotic activity)
How does V tachycardia present on ECG
Tidy looking QRS complexes
How does SVT present on ECG
Very fast palpitations (very fast QRS complexes)
How does first degree heart block present on ECG
Constant long PR interval
How does Mobitz type I (second degree heart block) present on ECG
PR interval progressively lengthens until QRS complex completely blocked
How does Mobitz type II (second degree heart block) present on ECG
Abnormally wide QRS complex
Some missing QRS complex (if serious)
How does complete heart block present on ECG
No link between P waves and QRS complexes.
Individual rates of P waves & QRS complexes tend to be constant.
How does a BBB present on ECG
Widened QRS complex
Which lead is always negative in a normal ECG
avR
Which are the only shockable arrhythmias
VT and VF
ST inversion and elevation and depression
Which means ischaemia/infarction
ST elevation: infarction
ST depression/inversion: ischaemia
What might a prolonged QT interval indicate
Acute MI, myocarditis, bradycardia
4 Types of SVT
- A fib
- Paroxysmal SVT
- A flutter
- WPW syndrome
Some examples of narrow complex tachycardias
- sinus tachycardia
- a flutter
Some examples of broad complex tachycardias
- ventricular tachycardia
- junctional tachycardia in acute MI
What is considered significant ST elevation (in terms of small square)
1 small square in limb lead
2 small squares in precordial lead
What types of ST depression are more likely to be pathological
- horizontal
- downwards
In which leads is it normal for T wave to be inverted
aVR
III
V1
4Hs and 4Ts that can cause a cardiac arrest
4H
- hypokalemia/hyperkalemia
- hypovolemia
- hypoxia
- hypothermia
4T
- toxin
- thromboembolism
- tamponade
- tension pneumothorax
4 life threatening arrhythmias
- VF
- Pulseless VT
- Asystole
- Pulseless electrical activity
Which 2 life threatening arrythmias are NOT shockable
- Asystole
- Pulseless electrical activity
ECG changes during hypothermia
- bradycardia
- āJā wave - small hump at the end of the QRS complex
- first degree heart block
- long QT interval
- atrial and ventricular arrhythmias
