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Electrocardiogram (ECG) (Interpretation (Rhythm Regular (normal) …
Electrocardiogram (ECG)
Interpretation
Rhythm
Regular (normal)
Regularly irregular (sinus arrhythmia, 1/2 heart block)
Irregularly irregular (AF, VF)
Rate
No. big squares between R-R/300;
BUT if irregular, #R x 10
100bpm: tachycardia
<60bpm: bradycardia
Admin
Name, age, DOB, date of ECG
Paper speed (25mm/s, large square 0.2s, small 0.04s)
P wave
Seen best (upright) in I, II, aVF
Present (if not, AF, SAN block, AVN rhythm)
Before each QRS (if not, heart block)
Morphology (bifid = P mitrale, peaked = P pulmonale)
PR interval
Start of P to start of QRS, normally 3-5 small squares (0.12-2s)
Prolonged (delated AVN conduction thus 1st degree HB)
Shortened (speedy AVN conduction thus shortcut i.e. WPW)
QRS
Represent septal depol, normally L-R, <0.12s (3 squares)
Wide QRS (defective ventricular conduction i.e. BBB)
Tall QRS (ventricular hypertrophy)
Short QRS (BBB, PE, pericarditis, myocarditis, hypothyroid, COPD)
QT interval
Start of Q to end of T, normal 0.38-0.42s
Prolonged QT (MI, myocarditis, U+E, congenital, drugs)
ST interval
Normally isoelectric
Elevation >1mm (infarction)
Depression >0.5mm (ischemia)
T wave
Normally inv aVR, V1, V2
Inversion (ischemia, old MI)
Peaked (hyper-K)
Flat (hypo-K)
Bundle branch block
Branches normally aligned, BBB can cause
one to depolarise faster than the other
LBBB (WiLLiaM W in V1, M in V6)
RBBB (MaRRoW M in V1 W in V6)
Axis
Sum of all ventricular forces during contraction,
normal lies -30 and +90
Check leads II and II (+ve = normal)
LAD -30 to -90 (LVH, L ant hemiblock, inf MI, WPW)
RAD +90 to +180 (RVH, PE, anterolateral MI, WPW)
Definition
Medical device allowing recording
of the electrical activity of the
heart from the body surface
Principles
Setup
Standard 12 leads
6 precordial leads giving horizontal plane (V1-V6)
6 limb leads giving vertical views (aVR, aVL, aVF, I, II, III)
Depolarisation detected and positive reflection, repolarisation opposite
Physiology
AP generated from cardiac cells as they depolarise and repolarise
Starts SAN, moves to AVN, His, bundle branches then Perkinje fibres,
then subendocardium (hemi bundles, L side has ant and posterior)
Types
Exercise ECG
Indication
Confirmation of IHD or exercise induced arrhythmias
MOA
Gradiated treadmill test with continuous ECG BP monitor
OR medication induced
Increase to max 90% for age
Stop if symptomatic (chest pain, SOB, pallor, exhaustion)
May see ST elevation, arrhythmia, BP change
CI
Recent MI, unstable angina, PE, dissection
Severe AS
Uncontrolled arrhythmia, HTN HF
Ambularory ECG
Indication
Suspected paroxysymal arrhythmia
MOA
Continous recording with a Holter monitor
Loop recorders can be activated by the patient when they experience symptoms
Standard 12 lead
Indications
Acute illness
Tachy/bradycardia or arrhythmia
