ECG Abnormalities Flashcards
Sinus Tachycardia
> 100bpm
Sinus Tachycardia causes
Infection Pain Exercise Anxiety Dehydration Bleed Systemic vasodilation (e.g. sepsis) Drugs (caffeine, nicotine, salbutamol) Anaemia Fever PE Hyperthyroidism Pregnancy CO2 retention Autonomic neuropathy Sympathomimetics
Sinus Bradycardia
Sinus rhythm <60bpm
Sinus Bradycardia Causes
Physical fitness Vasovagal attacks Sick sinus syndrome Drugs (beta blockers, digoxin, amiodarone) Hypothyroidism Hypothermia Increased ICP Cholestasis
AF
Absent P waves and irregular QRS complexes
AF causes
IHD Thyrotoxicosis Hypertension Obesity CCF Alcohol
Heart block definition
Disrupted passage of electrical impulse through AV node
1st degree HB
PR interval is prolonged and unchanging/regular
No missed beats
2nd degree HB Mobitz I
Wenckebach
PR interval becomes longer and longer until a QRS is missed, then the pattern resets
Regular Irregular
2nd degree HB Mobitz II
QRSs regularly missed e.g. P-QRS-P-QRS-P
Causes of 1st and 2nd degree HB
Normal variant Athletes Sick sinus syndrome IHD (especially inferior MI) Acute myocarditis Drugs (digoxin, beta-blockers)
3rd degree HB
Complete HB
No impulses passed from atria to ventricles
P waves and QRS complexes appear independently from each other
Patient becomes very bradycardic, may lead to haemodynamic compromise
Urgent treatment required
3rd degree HB causes
IHD (esp. inferior MI) Idiopathic (fibrosis) Congenital Aortic valve calcification Cardiac surgery/trauma Digoxin toxicity Infiltration (abscesses, granulomas, tumours, parasites
ST elevation
Normal variant (high take-off) STEMI Prinzmetal's angina- coronary artery spasm; pain without exertion triggered by hyperventilation, cocaine, tobacco Acute pericarditis (saddle-shaped) Left ventricular aneurysm
ST Depression
Normal variant (upward sloping) Digoxin toxicity (downward sloping) Ischaemia (horizontal) Angina NSTEMI Acute posterior MI (in V1-V3)
T inversion in V1-3
Normal (black patients and children)
RBBB
RV strain 9e.g. secondary to PE)
T inversion in V2-5
Anterior ischaemia
Hypertrophic cardiomyopathy
Subarachnoid haemorrhage
Lithium
T inversion in V4-6 and aVL
Lateral ischaemia
Left ventricular hypertrophy (LVH)
LBBB
T inversion in II, III and aVF
Inferior ischaemia
NSTEMI/unstable angina
ST depression
T wave inversion
non-specific changes, or normal
Ischaemia- changes in I, aVL, V4-6
Lateral heart
Circumflex artery
Ischaemia- changes in V1-3
Anterioseptal
LAD
Ischaemia- II, III, aVF
Inferior heart
RCA in 80%
Circumflex in 20%- left dominant
Posterior MI
Standard 12 lead ECG will not show Q waves, St elevation of hyperacute T waves
Instead you may find these changes but “upside down” in V1-3- Prominent R waves, flat ST depression, T wave inversion
If record V7-9 leads you may fins classic ST elevation –> posterior MI
Pulmonary embolism
Sinus tachycardia (commonest)
RBBB
Right ventricular strain pattern- RAD, dominant R wave, T wave inversion/ST depression in V1-2
Rarely- deep S waves in I, pathological Q waves in III and T wave inversion in III
Digoxin effect
Down sloping ST depression
T wave inversion V5-6
Any arrhythmia may occur
Hyperkalaemia
Tall tented T waves
Widened QRS
Absent/flattened P waves
Sine-wave appearance
Hypokalaemia
Small T waves
Prominent U waves
Peaked P waves
Hypercalcaemia
Short QT interval
Hypocalcaemia
Long QT interval
Right bundle branch block
QRS>0.12s
V1: ‘RSR’ pattern, dominant R
V1-V3 or V4: T wave inversion
V6: wide, slurred S wave
Right BBB causes
Normal variant (isolated RBBB)
PE
Cor pulmonale
Left BBB
QRS >0.12s
V5: ‘M’ pattern
V1: dominant S
I, aVL, V5-6: T wave inversion
Left BBB causes
IHD
Hypertension
Cardiomyopathy
Idiopathic fibrosis
Bifascicular block
LBBB + RBBB
Manifests itself as an axis deviation
Trifascicular block
Bifascicular block + 1st degree HB
Left ventricular hypertrophy
R wave in V6 >25mm OR sum of S wave in V1 + R wave in V6>35mm
Right ventricular hypertrophy
Dominant R wave in V1
T wave inversion in V1-3 or V4
Deep S wave in V6
RAD
Causes of low voltage QRS complex (QRS <5mm in all limb leads)
Hypothyroidism COPD Changes in chest wall impedance PE BBB Carcinoid heart disease Myocarditis + other heart muscle diseases Cardiac amyloid Doxorubicin cardiotoxicity Pericardial effusion Pericarditis