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The Normal ECG

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Normal EKG

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Normal EKG

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10steps in Analyzing EKGs

Rate

Rhythm

Axis

P wave

PR interval

QRS complex

ST segment

T wave

U wave

QT interval

All the above must be normal to call it a Normal EKG

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Determine the Heart Rate

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Heart Rate

Fig 4 - 13 Page 68

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Normal Sinus Rythm each P wave is followed by a QRS P waves normal for the subject (upright in

inferior leads) P wave rate 60 - 100 bpm with 10% = sinus arrhythmia

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Determine the axis -

1

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Normal Axis 30

to +90

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Determine the axis - 2

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Left Axis

Deviation

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Right AxisD

eviation

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Normal Frontal Axis

Between -30Degrees

and +90Degrees

Indicates that the

electrical activation of

the heart is occurring

down the normalpathway. Fig 4-14 Page 69

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Frontal Axis

both I and aVF +ve = normal axis lead I +ve and aVF -ve --- lead II +ve = normal axis

both I and aVF -ve = axis in the Northwest Territory

lead I -ve and aVF +ve = right axis deviation

lead II -ve = left axis deviation

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Frontal Plane Axis

R D

E D

L D

Normal

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Causes of Right Axis Deviation

ynormal finding in children and

tall thin adults

yright ventricular hypertrophy

ychronic lung disease even without

pulmonary hypertension

yanterolateral myocardial

infarction

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Causes of Right Axis Deviation

yLeft Posterior Hemiblock

yPulmonary Embolus

yWolff-Parkinson-White syndrome -

left sided accessory pathway

yAtrial Septal defect

yVentricular Septal defect

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Causes of Left Axis Deviation

Left anterior hemiblock

Q waves of inferior myocardial infarction

Artificial cardiac pacing

Emphysema

Hyperkalaemia

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Causes of Left Axis Deviation

Wolff-Parkinson-White syndrome- right

sided accessory pathway

Tricuspid atresia

Ostium primum

ASD

Injection of contrast into left coronary

artery

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Causes of a Northwest axis

(no man's land) Emphysema

hyperkalaemia

lead transposition

artificial cardiac pacing

ventricular tachycardia

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P Wave

Fig 4 - 17 Pg. 72

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Normal P waves height < 2.5 mm in lead II

width < 0.11 s in lead II

abnormal P waves seen in

right atrial hypertrophy,

left atrial hypertrophy,

atrial premature beat,

hyperkalaemia

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PR Interval

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PR Interval

0.12 to 0.20 s (3 - 5 small squares)

y short PR segment - Wolff-Parkinson-White syndrome orLown-Ganong-

Levine syndrome (other causes -Duchenne muscular dystrophy, type IIglycogen storage disease (Pompe's),HOCM)

y long PR interval -- first degree heartblock

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EKG Nomenclature

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Normal QRS Complexy< 0.12 s duration (3 small squares)

y for abnormally wide QRS considerright

orleftbundle branch block, ventricularrhythm, hyperkalaemia, etc.

y nopathological Q waves

y no evidence ofleft or right ventricularhypertrophy

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Q Waves Abnormal to have Q waves in V1, V2 and

V3

All other leads have small Q waves which

could be normal

Normal Q waves are less than .04 sec.

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R wave progression

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Progression of QRS complex in

the precordial leads

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ST Segment

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T waves

Normal T waves are

always concordant

with the QRS complex.

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U Wave

Concordant with T wave

More prominent in V1-V3

Source of U wave isunknown

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QT Interval

Bazetts: QT / Sqrt RR

MacFarlane: QT + 1.75 ( HR- 60)

The Easy Way

QT interval is 0.40 sec for a HR of 70

-0.02 sec for every increase of10 in HR +0.02 sec for every decrease of10 in HR

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Steps in Analyzing EKGs Rate

Rhythm

Axis

P wave

PR interval

QRS complex

ST segment

T wave

U wave

QT interval

All the above must be normal to call it a Normal EKG

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Web Sites toL

earn ECGhttp://endeavor.med.nyu.edu/courses/physiology/courseware/ekg_pt 1/ekg

menu.html

Excellent site to get an idea on the EKG tracing and get a spatial

orientation of all the leads. Animations are excellent

http://sones.uthscsa.edu/rfstump/index.html#toc

Good samples of12 lead EKG's, just like they look in thehospital

http://homepages.enterprise.net/djenkins/ecghome.html

Sample EKG with the criteria

http://www-health.santafe.cc.fl.us/health/VCCL/chpt5/ecg.html

Leads, measurements and abnormalities