how to read an ekg strip

8/3/2019 How to Read an EKG Strip

1/9

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.

Voltage is measured along the vertical axis.

10 mm is equal to 1mV in voltage. The diagram below illustrates the configuration of EKG graph paper and

where to measure the components of the EKG wave form

Heart rate can be easily calculated from the EKG strip:

When the rhythm is regular, the heart rate is 300 divided by the numberof large squares between the QRS complexes.

o For example, if there are 4 large squares between regular QRScomplexes, the heart rate is 75 (300/4=75).

The second method can be used with an irregular rhythm to estimate therate. 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 heartrate is 70 (7x10=70).

Normal Components of the EKG Waveform


2/9

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


3/9

ST segment

Indicates early ventricular repolarization Normally not depressed more than 0.5 mm May be elevated slightly in some leads (no more than 1 mm)

PR interval

Indicates AV conduction time Duration time is 0.12 to 0.20 seconds

QT interval

Measured from the Q to the end of the T. Represents ventricular depolarization and repolarization (sodium influx and

potassium efflux) V3, V4 or lead II optimize the T-wave. QT usually less than half the R-R interval

(0.32-0.40 seconds when rate is 65-90/minute) QT varies with rate. Correct for rate by dividing QT by the square root of

the RR interval.o http://www.qtsyndrome.ch/qtc.htmlo Normal corrected is < 0.46 for women and < 0.45 for men.

Prolonged QT may be inherited or acquired(predisposes to long QT syndrome andtorsades de pointe)

o Inherited - defective sodium or potassium channelso Acquired - drugs, electrolyte imbalance or MI

Atleast, 50 drugs known to affect QT (including: quinidine,amiodarone and dofetilide)

Electrode Placement and Lead Selection

Proper electrode placement is essential in order to acquire accurate EKG

strips. Most EKG monitor manufacturers have a set of placement guidelines

specific to their products.

The following are some general guidelines.

Skin preparation: Shave hair away from electrode placement site. Rub site briskly with alcohol pad. Rub site with 2x2 gauze.

Place electrode. Be sure that the electrode has adequategel and is not dry.
http://www.rnceus.com/ekg/ekgtp.htmlhttp://www.rnceus.com/ekg/ekgtp.htmlhttp://www.rnceus.com/ekg/ekgtp.htmlhttp://www.rnceus.com/ekg/ekgtp.html


4/9

3 lead placement:o Depolarization wave moving toward a positive

lead will be upright.

o Depolarization wave moving toward a negativelead will inverted.

o Depolarization wave moving between negativeand positive leads will have both upright andinverted components.

Five lead placement allows viewing of all leads within thelimits of the monitor.

Lead selection

Lead II is the same as standard lead two as seen in a 12 lead EKG.o It is the most common monitoring lead.o It is not the optimal monitoring lead.

V1 lead is the best lead to view ventricular activity and differentiatebetween right and left bundle branch blocks.

o The only way to view V1 is with a five lead system.o Therefore, MCL1 was designed to overcome the inconvenience of

a five lead system and provide all the advantages of V1 viewing.


5/9

Trouble shooting and tips

Change the electrodes everyday. Make sure all electrical patient care equipment is grounded. Be sure all the lead cables are intact. Some manufacturers require

changing the cables periodically.

Be sure the patient's skin is clean and dry. Make sure the leads are connected tightly to the electrodes. Patient movement frequently causes interference. For example, the action

of brushing teeth may cause interference that mimicsV-tach.

Sinus Bradycardia

Rate 40-59 bpm

P wave sinusQRS normal (.06-.12)
http://www.rnceus.com/ekg/ekgvt.htmlhttp://www.rnceus.com/ekg/ekgvt.htmlhttp://www.rnceus.com/ekg/ekgvt.htmlhttp://www.rnceus.com/ekg/ekgvt.html


6/9

ConductionP-R normal or slightly

prolonged at slower rates

Rhythm regular or slightly irregular

This rhythm is often seen as a normal variation in athletes, during sleep, or in

response to a vagal maneuver. If the bradycardia becomes slower than the SAnode pacemaker, ajunctional rhythmmay occur.

Treatment includes:

treat the underlying cause, atropine, isuprel, or artificial pacing if patient is hemodynamically compromised.

Sinus Tachycardia

Rate 101-160/min

P wave sinus

QRS normal

Conduction normalRhythm regular or slightly irregular

The clinical significance of this dysrhythmia depends on the underlying cause.

It may be normal.

Underlying causes include:

increased circulating catecholamines

CHF hypoxia PE
http://www.rnceus.com/ekg/ekgjeb.htmlhttp://www.rnceus.com/ekg/ekgjeb.htmlhttp://www.rnceus.com/ekg/ekgjeb.htmlhttp://www.rnceus.com/ekg/ekgjeb.html


7/9

increased temperature stress response to pain

Treatment includes identification of the underlying cause and correction.

Sinus Arrhythmia

Rate 45-100/bpm

P wave sinus

QRS normal

Conduction normal

Rhythm regularly irregular

The rate usually increases with inspiration and decreases with expiration.

This rhythm is most commonly seen with breathing due to fluctuations in

parasympathetic vagal tone. During inspiration stretch receptors in the lungsstimulate the cardioinhibitory centers in the medulla via fibers in the vagus

nerve.

The non respiratory form is present in diseased hearts and sometimes confused

withsinus arrest(also known as "sinus pause").

Treatment is not usually required unless symptomatic bradycardia is present.

Atrial Flutter
http://www.rnceus.com/ekg/ekgsar.htmlhttp://www.rnceus.com/ekg/ekgsar.htmlhttp://www.rnceus.com/ekg/ekgsar.htmlhttp://www.rnceus.com/ekg/ekgsar.html


8/9

Rate

atrial 250-350/min;

ventricular conduction

depends on the capability of

the AV junction (usually rate

of 150-175 bpm).

P wavenot present; usually a "saw

tooth" pattern is present.

QRS normal

Conduction2:1 atrial to ventricular most

common.

Rhythm

usually regular, but can be

irregular if the AV blockvaries.

Atrial flutter almost always occurs in diseased hearts. It frequently precipitates

CHF.

The treatment depends on the level of hemodynamic compromise.

Cardioversion, vagal maneuvers and verapamil are used when promptrate reduction is needed.

Otherwise, digoxin and other antiarrhythmic drugs can be used.Atrial Fibrillation


9/9

Rateatrial rate usually between400-650/bpm.

P wavenot present; wavy baseline is

seen instead.

QRS normal

Conduction

variable AV conduction; if

untreated the ventricular

response is usually rapid.

Rhythm

irregularly irregular. (This is

the hallmark of thisdysrhythmia).

Atrial fibrillation may occur paroxysmally, but it often becomes chronic. It

is usually associated with COPD, CHF or other heart disease.

Treatment includes:

Digoxin, diltiazem, or other anti-dysrhythmic medications to control theAV conduction rate and assist with conversion back to normal sinusrhythm.

Cardioversion may also be necessary to terminate this rhythm.

how to read an ekg strip

Documents