Basic EKG Dysrhythmia Identification

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Basic EKG Dysrhythmia
Identification

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How to Read an EKG Strip
EKG paper is a grid where time is measured along the horizontal axis.

• Each small square is 1 mm in length and represents 0.04 seconds.
• Each larger square is 5 mm in length and represents 0.2 seconds.




Heart rate can be easily calculated from the EKG strip:

• When the rhythm is regular, the heart rate is 300 divided by the
number of large squares between the QRS complexes.
o For example, if there are 4 large squares between regular
QRS complexes, the heart rate is 75 (300/4=75).
• The second method can be used with an irregular rhythm to estimate
the rate. Count the number of R waves in a 6 second strip and multiply
by 10.
o For example, if there are 7 R waves in a 6 second strip, the
heart rate is 70 (7x10=70).



Normal Components of the EKG Waveform

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P wave

• Indicates atrial depolarization, or contraction of the atrium.
• Normal duration is not longer than 0.11 seconds (less than 3
small squares)
• Amplitude (height) is no more than 3 mm
• No notching or peaking

QRS complex

• Indicates ventricular depolarization, or contraction of the ventricles.
• Normally not longer than .10 seconds in duration
• Amplitude is not less than 5 mm in lead II or 9 mm in V3 and V4
• R waves are deflected positively and the Q and S waves are negative

T wave

• Indicates ventricular repolarization
• Not more that 5 mm in amplitude in standard leads and 10 mm
in precordial leads
• Rounded and asymmetrical

ST segment