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Flashcards in Reading An ECG Deck (9)
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1. Introduction

Date/time of ECG


2. Heart rate

- number of large squares in one RR interval. Divide by 300
- if irregular: multiply number of complexes by 6


3. Heart rhythm

- regularly irregular
- irregularly irregular


4. Cardiac axis

- NORMAL: lead 2 has most positive deflection compared to leads 1/3

- RIGHT AXIS DEVIATION: lead 3 has most positive deflection, lead 1 should be negative

- LIGHT AXIS DEVIATION: lead 1 has most positive deflection. Leads 2/3 negative results


5. P waves

- p waves present?
- is each p wave followed by a QRS?
- do they look normal

If absent think AF


6. PR interval

- should be 3-5 small squares (0.12-0.2s)
- prolonged PR = AV block

1st degree: fixed prolonged PR interval
Mobitz type 1: PR slowly inc then there is a dropped QRS
Mobitz type 2: fixed PR interval but dropped beats
3rd degree: P waves and QRS complexes are completely unrelated

Shortened PR interval = smaller atria, accessory pathway


7. QRS complex

- width
Narrow (<0.12 sec)
Broad = ventricular ectopic (0.12 sec)
- height
Small <5mm in limb leads, <10mm in chest leads
- morphology
- delta wave (ventricles being activated earlier than normal from point distant to AVN)


8. ST segment

ST elevation: commonly caused by acute full thickness MI

ST depression: myocardial ischaemia


9. T waves

Tall T waves (>5mm in limb leads AND >10mm in chest leads)
Associated with: hyperkalaemia, hyperacute STEMI

Inverted T waves
Nonspecific sign of: ischaemia, BBB, PE, LVH

Biphasic T waves:
- t peaks
- indicative of ischaemia and hypokalaemia

Flattened T waves: ischaemia, electrolyte imbalance