8/8/2019 Pa Tho Physiology - 8 Step Method for Reading EKGs

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8 Step Method for Reading EKGs(Accordingto a Cardiology Fellow atRWJUH)

1. Is there a P-wave?a. Yes! there is organized atrial activityb. No! there is no organized atrial activity2. Is the P-wave a sinus P-wave?a. Check leads II and aVR:

i. Lead II should have a (+) deflection of P-waveii. Lead aVR should have a (!) deflection of P-wave

b. Yes to both! this is a sinus P-wavec. No to either! this is an ectopic P-wave

3. Is there a QRS after each P-wave?a. Yes! communication is present between atria and ventricles (although, may not

be totally normal, e.g. slowed)

b. No! communication is disrupted between atria and ventricles4. What is the rhythm (regularity)? ! this is an overall look at the EKG as a whole includingHR, ratio of P waves to QRS complexes, etc.

a. Each big box = 200 ms or a heart rate of 300 bpmb. Each small box = 40 msc. Height:

i. Each big box = 5 mmii. Each small box = 1 mm

d. Calculating heart rate: check distances between QRS"si. 1 big box = 300 bpm

ii. 2 big boxes = 150 bpmiii. 3 big boxes = 100 bpmiv.

4 big boxes = 75 bpmv. Formula: HR = 300/(# of big boxes between QRS"s)

5. What is the axis?a. Two methods:

i. Rough Measure: Check the QRSdeflection in leads I and aVF!If

both are (+), you have a normal axis(lower right quadrant); between 0

and 90 degrees

ii. Check for most isoelectric lead (leadwhere there is almost no activity

recorded)!

the axis must beperpendicular (90o) to this lead

1. Should be lead III! axis ofeither ~30

oor ~210

o

2. Since lead I should be (+), this means that an axis of 210o is notpossible and the axis is ~30

o)

b. An axis not in the lower right quadrant is indicative of some type of pathology(e.g. hypertrophy, obesity, etc.)

8/8/2019 Pa Tho Physiology - 8 Step Method for Reading EKGs

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6. What are the intervals?a. PR interval should be < 1 big box (< 200 ms)

i. Prolonged and constant! 1o AV blockii. Progressively longer PR until QRS is dropped! 2o Type I AV block

iii. Very few P-waves cause a QRS! 2o Type II AV blockiv.

Total dissociation; faster P-waves, slower QRS complexes at steady rates! 3

oAV block

b. QRS should be < 3 small boxes (< 120 ms); delayed repolarization! longer QRS! left bundle branch or right bundle branch block

c. QT, QTc! QTc is corrected for heart rate; should be < 440 (males) or 460(females)

i. Prolonged in ventricular arrhythmiasii. QTc = QT/[sqrt(RR interval)]

iii. Rough Measure: QT should be < ! RR interval7. Is there enlargement of the chambers?

a. Atrial: check leads II and V1i.

Lead II!

check mainly for RA abnormalities, but also for LAabnormalities

1. If P-wave deflection is > 2.5 small boxes (2.5 mm)! RAenlargement

2. If P-wave width is > 3 small boxes (120 ms)! LA enlargementii. Lead V1 ! check mainly for LA abnormalities, but also for RA

abnormalities

1. If P-wave (-) deflection is > 1.5 small boxes (1.5 mm) ! LAenlargement

2. If P-wave (+) deflection is > 2.5 small boxes (2.5 mm) ! RAenlargement

b. Ventricular: check leads and axis deviationi. LV hypertrophy

1. Lead aVL: if addition of absolute values of R and S-wavedeflections is > 24/20 small boxes (24/20 mm), there is LVhypertrophy; 24 in males, 20 in females

2. Leads V5/6 and V1: if addition of absolute values of R-wavedeflection in V5/6 and S-wave deflection in V1 is > 30 small boxes

(30 mm), there is LV hypertrophyii. RV hypertrophy

1. Right axis deviation (> 100o)8. Is there ST deviation?

a. Deviation up or down from baseline! ischemiai. Check for inverted T-wave (except aVR, where it should be inverted)

b. If Q-wave is about 1/3 or 1/4 of the R-wave! old infarct