- Check name, date, time of EKG
- Note if it was taken during episode of chest pain
- Rate
- Many methods exist for calculating rate
- If regular rhythm use the counting down method, assuming 25mm/sec stri
- Find and R wave on the rhythm strip that lands on the line for one of the larger boxes (0.2sec) and count each larger box line until you arrive at the next R wave -> 300bpm,150bpm, 100bpm, 75bpm, 60bpm, 50bpm
- Approximate if the second R wave is not situated exactly on the line
- If irregular count the number of complexes over 6 seconds and multiply by 10, or determine the rates for the closest complexes and the furthest complexes and divide by 2
- Rhythm
- Sinus if there is a P wave before every QRS and a QRS after every P wave, if the P waves are upright in leads II, III, aVF
- Atrial fibrillation if there are no p waves
- Atrial flutter at 2:1 block, look for the saw tooth pattern
- Blocks
- 10 – PR interval is longer than 0.20 seconds
- 20
- 1. Mobitz type 1 (Wenchebach): progressively elongated PR interval eventually resulting in complete failure to conduct and a lack of ventricular contraction
- 2. Mobitz type 2: unexpected nonconducted atrial impulses
- 30 – complete dissociation of atrial and ventricular impulses
- Axis
- Look at QRS complexes in leads I and aVF
- Both upright – normal
- If lead I is downwards – right deviation
- If lead aVF is downward look at lead II
- 1. Upright – normal
- 2. Downwards – left deviation
- Look at QRS complexes in leads I and aVF
- Intervals
- PR 0.12-0.2 seconds
- QRS ≤ 0.10 seconds
- QTc ≤ 0.44 seconds → calculation: QT Interval / √ (RR interval)
- P wave morphology
- Look at lead II
- Right atrial enlargement if p wave initial component is enlarged taller than 2.5m
- Look at lead V1
- Left atrial enlargement if p wave has a downward deflection of terminal componen
- Look at lead II
- QRS complex morphology
- Right ventricular hypertrophy if tall R waves in V1 and V2, deep S wave in V6 and right axis deviation
- Left ventricular hypertrophy is tall R waves in V6, deep S wave in V1, AND one of:
- R in V5 or V6 ≥ 35mm
- R in aVL > 11mm
- R in I > 15m
- Incomplete BBB – QRS 0.10-0.12 seconds
- LAFB: Q wave in I, aVL; initial R wave in II, III, aVF
- LPFB: Q in II, III, aVF; initial R wave in I, aV
- Complete BBB – QRS > 0.12 seconds
- RBBB: R‘ in V1 (bunny ear appearance), and S in V6
- LBBB: absent normal R in V1 and Q in V6; terminal R’ in V6 and downward deflection in V1 (W appearance
- Q waves – normal in V6 and aVL; pathologic if >0.04 seconds or depth >25% QRS height
- ST changes – ST segment and T waves
- MI
- ST elevation – returns to baseline in days
- T wave inversion – weeks to months
- Q waves – persists
- ST segment may remain elevated if fibrotic scar develop
- Wellen’s syndrome – proximal LAD stenosis
- Biphasic T waves in V2 and V3
- Brugada syndrome
- Persistent ST elevations in V1-V3
- RBBB appearance without the terminal S waves in the lateral lead
- Pericarditis
- Diffuse ST elevation
- PR depressio
- Hyperkalemia
- Tall peaked T waves
- Flat P waves
- Wide QR
- Hypokalemia
- U wave
- ST depression
- Flat T wave
- MI
Further Reading:
- How to Read an EKG (Source: South Sudan Medical Journal)
- How to Read an ECG (Source: Geeky Medics)