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Clinical Skills - EKG Guide By Izzy Pines Basics on Waveforms: P wave: 1 st deflection. Represents atrial depolarization PR interval: Represents conduction through the AV node QRS complex: Represents ventricular depolarization and contraction ST segment: Represents interval between depolarization and repolarization QT interval: Represents the entirety of ventricular activity T wave: Represents ventricular repolarization U wave: Rarely seen on EKG. Represents recovery of the Purkinje conduction fibers Learn to Read EKGs Systematically: Method 1: AHI AHI r A te r H ythm I ntervals A xis H ypertrophy I schemia Method 2: Rules of 4’s A. 4 initial features 1. History 2. Rate 3. Rhythm 4. Axis B. 4 wave forms 1. P wave 2. QRS complex 3. T wave 4. U wave C. 4 intervals/segments 1. PR interval 1

EKG Guide · EKG Guide

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Page 1: EKG Guide · EKG Guide

Clinical Skills - EKG GuideBy Izzy Pines

Basics on Waveforms:

P wave: 1st deflection. Represents atrial depolarizationPR interval: Represents conduction through the AV nodeQRS complex: Represents ventricular depolarization and contractionST segment: Represents interval between depolarization and repolarizationQT interval: Represents the entirety of ventricular activityT wave: Represents ventricular repolarizationU wave: Rarely seen on EKG. Represents recovery of the Purkinje conduction fibers

Learn to Read EKGs Systematically:

Method 1: AHI AHI

rAterHythm Intervals

Axis Hypertrophy Ischemia

Method 2: Rules of 4’s

A. 4 initial features1. History2. Rate3. Rhythm4. Axis

B. 4 wave forms1. P wave2. QRS complex3. T wave4. U wave

C. 4 intervals/segments1. PR interval2. QRS width3. ST segment4. QT length

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What are you looking for? Rate : 60-100 bpm

o Use the dark lines (big boxes) to count 300, 150, 100, 75, 60, 50, 42 (bpm)o Count number of QRS on strip in 6 second interval and multiply by 10o Divide 300 by the number of QRS complexes present

Rhythm: Is it sinus?o Sinus = P before every QRS, QRS after every Po Other options = irregular, junctional, ventricular, ectopic beats

Axis: Normal, left axis deviation, right axis deviation?o Normal = Upright QRS complexes in leads I, II, and aVFo Left axis deviation = upright QRS in lead I, downward QRS in aVFo Right axis deviation = upright QRS in aVF, downward QRS in lead I

P waveo Check lead II for p wave pathology because they’re most prominento Duration <120ms (<3 small boxes)o Amplitude <2.5mm (2.5 small boxes) o Do they occur regularly? – march them outo Are the P-Waves smooth, rounded, and upright?o Do all P-Waves have similar shapes?o Note: biphasic P wave in V1 is normalo Abnormalities:

Peaked P waves (>2.5mm tall) (P pulmonale) = right atrial enlargement (likely d/t pulm HTN)

Notched P waves (P mitrale) = left atrial enlargement (likely d/t mitral stenosis) Inverted P waves = ectopic atrial rhythm Variable P waves = multifocal atrial rhythms

P pulmonale P mitrale

Left axis

Severe

Right Axis

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Image source: http://www.medicine-on-line.com/html/ecg/e0001en.htm - 305

PR intervalo Duration = 120-200ms (<1 big box)o Is the PR Interval constant across the ECG tracing?o Abnormalities

Consistently > 200ms (NO dropped QRS’s) = 1st degree AV block Progressive increase in PR interval then dropped QRS = 2nd degree AV block Type 1 Constant PR interval then dropped QRS = 2nd degree AV block Type 2 PR interval < 120ms = Junctional rhythm, Wolff-Parkinson-White syndrome or Lown-

Ganong-Levine syndrome Occur d/t accessory pathways Hallmark of WPW = delta wave

1st Degree AV BlockImage source

2nd Degree AV Block, Mobitz Type 1 (Wenckebach)Image source

2nd Degree AV Block, Mobitz Type 2Image source

3rd Degree AV Block (complete heart block)Image source

Above: Type A WPW Syndrome (dominant R in V1 = left sided accessory pathway)Type B WPW Syndrome (dominant S in V1 = right sided accessory pathway)Image source

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Page 4: EKG Guide · EKG Guide

QRS complexo Duration < 120ms (3 small boxes)o Look for Q waves in all leadso Check QRS progression in precordial leads. Should look like this:

o Abnormalities: pathologic Q waves (ddx = MI, hypertrophic cardiomyopathy (CM), infiltrative

myocardial dz, rotation of heart, lead placement errors) > 40 ms (1 small box) wide > 2 mm (2 small boxes) deep > 25% of depth of QRS complex Seen in leads V1-3

> 120ms = Bundle branch block RBBB (rabbit ears) = RSR’ in V1 and V2 LBBB = broad notched R in V5, V6, I, and aVL, reciprocal changes in V1-2

Normal q wave in V6 Pathologic q waves in II, III, avFImage source Image source

Right Bundle Branch BlockImage source

Left Bundle Branch BlockImage source

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ST segmento Flat relative to baselineo Look for sloping, up sloping vs down slopingo Abnormalities:

ST elevation (check this out) = AMI, coronary vasopasm, pericarditis, early repol, LBB, LVH, ventricular aneurysm, Brugada syndrome, Ventricular pacer, increased intracranial pressure (ICP)

KNOW patterns of ISCHEMIALimb Leads Precordial Leads

I - high lateral aVR V1 - anteroseptal V4 - anteriorII - inferior aVL - high lateral V2 - anteroseptal V5 - lateralIII - inferior aVF - inferior V3 - anterior V6 - lateral

ST depression, unspecified = AMI/NSTEMI, reciprocal changes from STEMI, RVH, RBBB, LBBB, LVH, Ventricular pacer

Down sloping ST depression = digoxin, hypokalemia, Up sloping ST depression + De Winters T waves (symmetrically peaked) = acute

LAD occlusion Horizontal ST depression = posterior MI, SVT

Different morphologies of STEMIImage source

QT lengtho Look at the corrected QT interval at the top of the EKG (QTc) because it varies with

heart rate. QTc estimates Qt if HR was 60 bpm

o QTc duration <440ms for men and <460ms for womeno Abnormalities:

Prolonged = drugs, hypokalemia, hypomagnesaemia, hypocalcemia, hypothermia, MI, increased ICP, congenital long QT syndrome

< 350ms = hypercalcemia, digoxin, congenital short QT syndrome T wave

o Amplitude < 5 small boxes in limb leadso Should be upright in all leads except aVR and V1o Abnormalities:

Peaked (almost as tall as QRS) = hyperkalemia Upright T wave in V1 = acute ischemia (if new) otherwise CAD Inverted = normal in kids, MI, LBBB & LVH (in I, aVL, V5-6), RBBB (in V1-3),

RVH & PE (in V1-3, and II, III, aVF), HCM (V1-6), increased ICP Biphasic = hypokalemia (down then up), MI (up then down) Flattened = electrolyte abnormality (if generalized), MI (if in contiguous leads)

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Peaked T waves – hyperkalemiaImage source

U waveo Best seen in V2 or V3o Amplitude = 0.5MM (1/2 small box)o Inversely proportional to HRo Abnormalities:

>2mm or 25% of T wave = bradycardia, severe hypokalemia, digoxin, phenothiazine, clas Ia anti-arrhythmics, Class III anti-arrhythmics

Inverted = MI, CAD, HTN, valve disease, congenital heart disease, CM, hyperthyroidism

References:http://lifeinthefastlane.com/ecg-rule-of-fours/

http://www.practicalclinicalskills.com/ekg.aspx

http://ekg.academy/

http://www.ecg-quiz.com/

http://acls-algorithms.com/rhythms/

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