dr. Tania Andriani Sabrawi, SpJP

Riwayat Pekerjaan

Riwayat Pendidikan

THE ECG MADE EASY

Tania Andriani Sabrawi

Pacemaker cells

(spontaneously generate electrical activity, and conduct it throughout the heart)

Contraction of atria and ventricles 🡪 regulated by transmission of electrial impulse

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Modified cardiac muscle cells 🡪 the cardiac conduction system

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Automaticity 🡪 Generating the cardiac rhythm

Spread & coordinate the electrical activity

Fastens conduction 🡪 essential for effective pressure generation of ventricles

Conduction Delay 🡪 allows filling of the ventricles

ECG Reading

Electrical activity precede the mechanical activity

1. Identity
2. Calibration : amplitude and paper speed
3. Lead placement : lead II (+) dan aVR (-)

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NOT FEASIBLE TO READ

1. Rhythm
2. Heart rate
3. Axis
4. P Wave
5. PR Interval
6. QRS
7. ST Segment
8. T Wave
9. QTc
10. U wave

Sinus Rhythm/not?

• Normal AV conduction : P followed by QRS
• Rate must be 60-100 bpm
• Regular R-R Interval
• (+) P wave lead II, and (-) P Wave lead aVR

Heart Rate: How fast/slow?

R-R Interval

300/R-R interval

Heart Rate: How fast/slow?

QRS in 6 seconds (30 medium boxes), multiply by 10

Cardiac Axis

• Quadrant method
• Look for QRS morphology in lead I and aVF

P Wave

• Atrial depolarisation
• Look for P wave in lead II and V1
• What to assess?
• Amplitude Normal < 2.5 mv
• Duration Normal < 0.10 s

PR Interval

Normal PR interval :120 to 200 ms (3-5 small boxes)

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PR segment is the usually isoelectric region beginning with the end of the P wave and ending with the onset of the QRS complex

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QRS

• initial negative deflection is called the Q wave
• first positive wave is the R wave
• first negative wave after a positive wave is the S wave
• Pay attention to the morphology, transitional zone, and QRS duration (Normal <0.12 s)

Pathologic Q wave?

• Q wave is NORMAL, unless:
• Duration is >0.04 s
• Amplitude is >25% (1/3) R amplitude
• In some cases, there is no R wave at all (QS morphology)
• Look for neighbouring pathological Q waves

ST Segment-T Wave

• ST-T wave begins as a low-amplitude
• Gradually evolves into a larger wave, the T wave
• The onset of the ST-T wave is the junction or J point
• Level of the ST segment generally is measured at the J point
• Normal varies with race, age, & sex
• Typically higher in V2

T Wave

• Usually concordant with QRS complex
• Discordant T wave usually abnormal
• T wave typically negative in V1-V2
• Normal amplitude:
• <15 mm in precordial lead
• <5 mm in limb lead

T Wave

• Can give us some information about
• Ischemia/infarction
• Any electrolytes abnormalities
• Structural heart diseases?
• Non-cardiac/pulmonary diseases (cerebrovascular event)
• Inflammation/infectious diseases
• Note: Inverted T wave can be a normal variation

U Wave

• Repolarization of purkinje fibers
• After T wave
• Amplitude: <2mm or <1/10 T-wave

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QTc

• Always include QT (QTc) Assessment
• Represent total time of depolarisation and repolarisation
• Measured from beginning of QRS complex to end of T wave
• Prolonged QTc : prone to life-threatening Ventricular arrhythmias
• Note that QT interval correlates with Heart rate

Is the QTc prolongation reversible?

• risk factors associated with QTc prolongation
• Non-modifiable
• congenital LQTS
• Structural heart disease
• Modifiable
• hypocalcaemia, hypokalaemia, hypomagnesaemia
• concomitant use of QTc-prolonging medications and bradycardia

But remember…

• Always start from clinical data
• Know what to expect and where to look
• Identify any emergencies

Take Home messages

• ECG is FUN and EASY
• Be patient. Read your ECG systematically so you won’t miss anything
• Be familiar with abnormalities, and normal variations
• Practice makes perfect!

HANK YOU

LVH/RVH/BVH?

Notice any abnormalities?

Bundle Branch Blocks: Look for the bunny!