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EKG Basics

S. Parvez Quadri

Chief ResidentAdvocate Christ Medical Center

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White on Right, Smoke over Fire

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I

IIaVF

III

aVLaVR

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One small box = 0.04 s

One large box = 0.2 s

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Systematic Approach!

Rate

Rhythm

Axis Intervals

Hypertrophy

Ischemia/Infarction

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Rate

Normal = 60100 beats/min

Tachycardia > 100 beats/min

Bradycardia < 60 beats/min

Count the number of QRS complexes in a 6 second interval and multiple by 10

You MUST memorize these numbers!

Or rate = 300/number of large boxes

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Rhythm

Sinus Rhythm

P before every QRS

QRS after every P Upright P in lead II

If your EKG does not

meet these criteria, itis not sinus rhythm

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Axis

Normal axis =

-30 to 90 degrees

Is it positive in I and aVF?

Where is the QRS biphasic?

I

IIaVFIII

aVLaVR

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Segments and Intervals

PR < 0.2 s (< 5 small

boxes)

QRS < 0.12 s (< 3 small

boxesQTeyeball to make

sure < RR

QTc < 0.45s

Why do we need to correct the QT interval?

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Atrial Hypertrophy

Lead II characteristics

Prolonged P wave > 120s = LAEPeaked P wave > 0.25 mV = RAE

V1

II

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Ventricular Hypertrophy

Right ventricular enlargement

R > S in V1

Left ventricular enlargement

many criteria

Bigger of S in V1 or V2 + R

in V5 or V6 > 35 mV

R in aVL > 11 mV

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Ischemia/Infarction

ST abnormalities

ST elevation or

depression

T wave abnormalities

Q waves

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Sinus tachycardia-PE, anemia, pain

Rate = 110

Rhythm = nl sinus

Axis = normal (around 60) Intervals = nl

Hypertrophy = none

Ischemia/Infarction = none

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Left atrial abnormality, LVH

Rate = 80

rhythm = nl sinus

axis = almost left axis (-30)

intervals = nl (QRS = 110, upper limit of normal) hypertrophy = LVH (V2 + V5 > 35, aVL > 11)

Ischemia/Infarction = non-specific ST-T abnormalities)

Pt had cardiomyopathy secondary to anthracycline chemotherapy for her history of breast

cancer

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A fib with RVR

Rate = 110

Rhythm = atrial fibrillation with RVR

Axis = nl, 30 Intervals = nl

Hypertrophy = nl

Ischemia/infarction= non-specific ST-Tchanges in II, III, aVF

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NSR with repolarization

abnormality ( normal)

Rate = 90

Rhythm = nl sinus

Axis = normal (around 60) intervals = nl (PR = 120, QRS = 80, QT = nl)

Hypertrophy = none

Ischemia/Infarction = none

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