ECG Flashcards
What leads correspond to anteroseptal view and what artery supplies it
V1-V4 - left anterior descending
What leads correspond to inferior view and what artery supplies it
II, III, aVG - right coronary artery
What leads correspond to anteolateral and what artery supplies it
V4-V6, I, aVL - left anterior descending or left circumflex
What leads correspond to lateral view and what artery supplies it
I, aVL, V5-6 - left circumflex
How many seconds in a small square
0.04 seonds
What represents a positive deflection
When the electrical activity of the heart travels towards a lead
What represents a negative deflection
When the electrical activity travels away from a lead
What happens if R wave > S wave
Depolarisation moving towards lead
What happens if S wave > R wave
Depolarisation moving away from that lead
Normal cardiac axis
Overall direction of electrical activity towards leads I, II, and III
Right axis deviation
Right ventricular hypertrophy
Lead I to become more negative and lead III to be positive
Left axis deviation
Lead I to be more positive and deflection in III to be negative
What is P waves are absent and there is an irregular rhythm
AF
What is the normal PR interval
3-5 small squares
120-200 milliseconds
What occurs in prolonged AR
First degree heart block (SAN->AV)
What is the ECG sign for Mobitz T1
PR interval slowly increases then there is a dropped QRS complex
What is the ECG sign for Mobitz T2
If PR interval is fixed but there are dropped beat
What is the ECG sign for third degree heart block
If P waves and QRS complex unrelated
Where is first degree heart block
Between SAN and AVN
Where is second degree heart block
I: occurs in AV node, II: occurs after AV node in bundle of His or Purkinje fibres
Where is third degree heartblock
Occurs anywhere from AV node down (complete heartblock)
How to diagnose Wolff Parkinson White Syndrome
Delta wave and tachyarrhythmia
What is the normal width of the QRS complex
Under 0.12 seconds (can be atrial ectopic)
What is abnormal width for QRS complex
Over 0.12 seconds (abnormal ventricular depolarisation or bundle branch block)
What is normal height for QRS
Small - less than 5mm in limb leads or les than 10mm in chest leads)
When should RS transition begin
Transition from S>R to R>S waves should occur in V3 or V4.
What does poor RS transition indicate
Previous MI
What is the J point
S waves joins the ST segment
What is ST elevation
Greater than 1mm in 2 or more contiguous limb leads, or over 2mm in 2 or more chest leads. MI
What is ST depression
Over 0.5mm in over 2 contiguous leads indicates myocardial ischaemia
What are tall T waves
Over 5mm in limb leads and over 10mm in chest leads
Hyperkalameia/hyperacute STEMI
What are inverted T waves
Normally inverted in V1 and III inversion is normal
Otherwise:
Ischaemia, BBB, PE, left ventricular hypertrophy, hypertrophic cardiomyopathy
What is V4-V6 T wave inversion
LBBB
What is V1-V3 T wave inversion
RBBB
What are biphasic T waves a sign of
Ischaemia and hypokalaemia
What are flattened T waves a sign of
Ischaemia or electrolyte blanace
What are U waves
Over 0.5mm deflection after T wave in V2 or V3
Electrolyte imbalance, hypothermia, or antiarrhythmic therpay (digoxin, procainamide or amiodarone)
What leads correspond to posterior view and what artery supplies it
Tall T waves in V1 or V2 and left circumflex/right coronary
