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38 Cards in this Set
- Front
- Back
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What does the P wave represent?
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Atrial depolarisation
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What are the normal parameters of a P wave?
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Positive
0.6-0.12s 2-3mm |
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In which lead is the P wave biphasic?
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V1
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In which lead is the P wave negative?
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aVr
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In which conditions is the P wave peaked/ notched/ enlarged?
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Atrial Hypertrophy
PE Heart failure Valvular disease COPD |
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Why would the P wave be absent?
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Junctional/ AF rhythm
Conduction non via the SAN |
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Why would the P wave be varying?
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Damage near the SAN
Wandering pacemaker Impulse from different sites |
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Why would the P wave be inverted?
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Retrograde/ reverse conduction from the AV junction
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What does the QRS complex represent?
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Ventricular depolarisation
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What are the normal parameters of a QRS complex?
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5-30mm
50% of PR interval or <0.12s |
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In which leads is the QRS complex negative?
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aVr
V1-V3 |
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What condition are associated with a deep and wide QRS complex?
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MI
Ventricular hypertrophy Q > 0.4s |
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Why would the QRS complex be widened?
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>0.12s = ventricular conduction delay
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Why would the QRS be absent?
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AV block/ ventricular standstill
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What does it mean when P waves and the QRS complex is not 1:1?
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Complete uncoupling = complete heart block
Impulse may have originated in the ventricles = ventricular arrhythmia |
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What does a notched R wave suggest?
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Bundle branch block
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What is the duration of a normal PR interval?
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0.1-0.2s
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What does the PR interval represent?
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Pulse from the atria to the AVN
Delay at the AV junction as the impulse travels to the bundle of His to the right and left bundle branches |
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What does a prolonged PR interval suggest?
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Heart block
Digoxin toxicity Ischaemia/ conduction tissue disease |
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What does a short PR interval suggest?
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The impulse didn't originate in the SAN
Junctional arrhythmia Pre- excitation syndromes Accessory pathway e.g WPW |
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What does the QT interval represent?
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Ventricular depolarisation and repolarisation
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What duration is a normal QT interval?
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Corrected
<0.44 males <0.46 females No more than 50% of the R-R distance |
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What determines the QT interval?
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Heart rate
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What causes a prolonged QT?
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Class 1a anti arrhythmic drugs
Congential Increased refractory period = Torsades de Points risk |
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What causes a short QT interval?
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Hypercalcaemia
Digoxin toxicity |
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Name 7 drugs that increase the QT interval?
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Domperidone
Methadone Amiodarone Thioidazine Haloperidol Clarithomycin/ Erythromycin Quinidine |
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What does the ST segment represent?
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End of ventricular conduction, beginning of repolarisation
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What causes a depressed ST?
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Ischaemia
Digoxin toxicity |
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What causes an elevated ST?
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MI
(injury) |
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What does the T wave represent?
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Ventricular repolarisation
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In which leads is the T wave positive?
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1
2 V3-V6 |
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What is the normal duration of the T wave?
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0.5mm in 1/2/3
Up to 1m in precordial leads |
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What does a notched or pointed T wave represent (in adults)?
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Pericarditis
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What does a tall/ peaked T wave represent?
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Myocardial injury
Hyperkalaemia |
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What do bumps mean?
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Hidden P waves
Atrial depolarisation, impulse originating above ventricles |
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What is a U wave?
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Recovery of purkinje/ ventricular conduction fibres
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When is the U wave more prominent?
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Digoxin toxicity
Hypercalcaemia Hypokalaemia Bradycardia |
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When is a J wave seen?
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Hypothermia
Subarachnoid haemorrhage Hypercalcaemia |
