7/24/2017

Practical Intro to EKGs

Reid B. Blackwelder, M.D. ([email protected]) Professor, Family Medicine East Tennessee State University

Basics - Physiology Basics – “Alphabet” The heartbeat creates many cellular depolarizations The first upward deflection is the P wave When going toward positive leads, get – It represents atrial depolarization – Positive deflections The PR Interval is the time between atrial and ventricular When going away from positive leads, get depolarization – Negative deflections The QRS complex represents ventricular depolarization The ST segment is next EKG is a summation measurement of many cellular events The represents ventricular repolarization

Review “Alphabet” QRS Nomenclature PR Interval ST Segment Upward deflection is an R wave P wave A second positive deflection is given a prime designation - T wave RSR’ A downward deflection preceding an R is a Q wave A downward deflection that follows an R is an S wave If only negative deflection is present it is a QS complex Ventricular depolarization is called “QRS” – QRS Although not all parts may be present

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R Examples of QRS Complexes Basics - Standards

Three limb leads R – I, II, III Three augmented limb leads – aVR, aVL, aVF Six chest leads Q QS – V 1 - V 6 Q S

Basics – Standard Form Basics - Strip

I aVR V 1 V 4 Big box = – 200 msec (0.2 sec) II aVL V 2 V 5 – 5 small boxes Little box = III aVF V3 V 6 – 40 msec (0.04 sec) – Also 1 mm Rhythm strip (II or V 1, usually – the atrial leads)

Review of Boxes

“The System”

Only one of many ways to do this!

4 small boxes 0.16

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Caveats Caveats We will not cover “Cool ” Difficult to do in groups Remembering criteria is not expected – Everyone is at a different level – Or even encouraged until you’re ready Lots of material in a compressed session Shoot for “Normal” vs. “Not Normal” – Your brain will “get full” before we finish! The only pattern to learn is “Normal”! – The handout is more complete than you need You have everything in the handout Keep Calm and Carry On!

The Basic Structure Review

Validity Validity Rate Rate Rhythm Rhythm Axis Axis Hypertrophy Hypertrophy /Infarction Ischemia/Infarction

Validity Standardization Box

Clinical context for test, right patient, etc – When handed an EKG, ask … – “Why was this done?” and – “How is the patient?” Look for voltage standardization curve – Two big boxes tall, or 10 mm/mV – Is also at the bottom of the strip

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Validity Validity QRS in Lead I should be opposite that in AVR And QRS is + in Lead I An “issue” noted in validity does not necessarily mean the R-wave should progress in chest (V) leads such that by tracing is invalid V4 the R-wave is most prominent Any abnormalities should generate “Differential Diagnoses” – Represents the left Review an old EKG

Poor R wave progression Validity Visuals

• Differential Dx?

Review of Validity Poll Question: The rate is closest to: Name, clinical context 1. 150 Standardization box 2. 100 QRS in I and aVR generally opposite 3. 75 R wave progresses in chest leads Compare with old EKG 4. 60 5. 50

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Rate Rate Normal rate 60-100 – <60 bradycardia Rate=300/# of large boxes between R- – >100 waves, or Basic pacing rates: Memorize: – Atria 80/min – 300, 150, 100, 75, 60, 50, 43, 37 – Junctional 60/min – Count at each large box after first R – Ventricular 40/min – But a rate does NOT determine pacer

Review of Rate Rate Calculation 300 150 300 150 100 75 100 75 60 50 43 37

Cumulative Review The is closest to: Validity 1. 150 – Context – Standardization box 2. 100 – I and aVR 3. 75 – R wave progression 4. 60 – Old EKG 5. 50 Rate – 300, 150, 100, 75, 60, 50, 43, 37

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Poll Question: Is this a sinus rhythm? Rhythm – Basic Questions 1. Yes Is it REGULAR? Is it SINUS? 2. No What are the INTERVALS? – PR – QRS – QT

Rate & Rhythm Rhythm - Regularity

Truly done as “Gestalt” Regular (usually “Fairly regular”) – Learning steps so you will usually Regularly irregular – Implement by steps (with pauses) – Group or pattern beating – How to cut your time in half! – Predictable Look at rhythm strip for both Irregularly irregular Trust your eyes for “not normal” – Chaotic – Unpredictable

Rhythm - Sinus Rhythm - Sinus

Often hear: P before QRS, QRS after P A positive P wave in II This really means an atrial relationship to A pacer from the SA node (sinus) should ventricles always be positive if – What are the Atrial leads? Leads placed correctly and – No dextrocardia For SINUS rhythm must also have… The why is a “Pearl”

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Rhythm - Sinus Rhythm - Intervals

Wide vs. Narrow QRS is clinically important Check PR interval – Covered in Handout Start of P to start of QRS – Not covered here Normal is 0.12-0.20 sec – Next level after “Foundation” work 3 –5 small boxes

Rhythm - Intervals PR Interval First degree AV block, PR > .20 Start Second degree AV block – Mobitz type I (Wenkebach) – Mobitz type II Third degree AV block PR interval can also be too fast Finish at 4 small boxes: 0.16 – Accessory pathway – WPW, LGL, etc

Rhythm - Intervals By the Way…

Really cool stuff!! First We won’t talk about it – Validity Get the basics down before taking on Second weird rhythms – Rate Third – Rhythm

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Rhythm - Intervals QRS Interval

Check QRS width Start – Start of complex to end – Normal 0.10- 0.12 2 ½ to 3 small boxes Look at QRS morphology, too – Should be crisp, single line Finish at 2 small boxes: 0.08 sec

Rhythm - Intervals Rhythm - Intervals

If QRS is wide, then If RSR` present, or – By definition a QRS is “slurred” or has “shoulder”, but – RSR` Interval not wide or prolonged… in V 1, V 2 is RBBB in V 5, V 6 is LBBB

Rhythm - Intervals Shoulder IVCD Interventricular Conduction Delay IVCD, or “Early BBB”, or “Incomplete BBB” Clinical Relevance?

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Rhythm - Intervals Rhythm - Intervals Check QT interval Handout has more on – Start of QRS to end of T – BBB Depolarization to repolarization – IVCD – For rate between 60 - 100, – Hemiblocks QT < 1/2 R-R interval Not foundation material Around 0.36-0.44 sec Very clinically important – R on T phenomenon

QT Interval Is this a sinus rhythm? First R Rate about 80, so… Second R 1. Yes 2. No

Halfway: 0.36

Validity Cumulative Review – Context – Standardization box – I and aVR – R wave progression – Old EKG Brain Alert! Rate – 300, 150, 100, 75, 60, 50, 43, 37 Rhythm It’s getting full… – Regular or not – Sinus or not – Intervals

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Poll Question: The axis is in which quadrant? Axis

1. Normal Use I and aVF for quick scan 2. LAD – The thumb method 3. RAD Normal is + QRS in both 4. Indeterminate – Two thumbs up 5. Not sure + in I, - in aVF – (LAD)

Axis In which Quadrant is the Axis?

- in I, + in aVF I + F – – (RAD) LAD - in I, - in aVF – Really not normal! – Differential?

Axis Axis I – I + Main goal now is to identify normal axis or not F – F – But work to be more specific with respect to Indeterminate LAD degree of axis Why? I – I + F + F + RAD Normal

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Axis Axis

Normal: 0 to+90 degrees Strive to give degree measurement Leftward (or LAD) 0 to -29 Look for isoelectric lead LAD: -30 or more degrees – As much + as – deflection RAD: > or = +90 degrees – The axis is perpendicular to it

Axis 12 Lead Basic Form Perpendicular leads without the graph Perpendicular Leads – Cool Trick! Use the 12 lead structure (all leads in 30°) I aVR – I and aVF Degrees 0 and 90 – II and aVL II aVL Degrees 60 and -30 – III and aVR III aVF Degrees 120 and 30

Positive in I What is the Axis? The axis is in which quadrant?

Lead II 60 1. Normal Most isoelectric 2. LAD Perpendicular lead 3. RAD 4. Indeterminate

Positive in aVF 5. Not sure

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Poll Question: What hypertrophy is suggested in V1? Hypertrophy

1. None Atrial – Must have sinus rhythm! 2. LAE – Look at P wave in leads II and V 1 3. RAE Ventricular (Many criteria exist) 4. LVH – Cannot do with a BBB 5. RVH – Look at QRS in chest leads

Hypertrophy - Atrial Normal P wave Hypertrophy - Atrial – Smooth in morphology RAA – < 2 ½ small boxes high and wide (II) – Lead II: – In V 1 Tall P-wave (>2.5 mm) Can be all positive “P-pulmonale” Can be symmetrically biphasic – V 1: Left atrium has a little more muscle Large tall P Determines time of conduction Tall in both!

P Wave of RAA Hypertrophy - Atrial LAA – Lead II: P-wave with notching “P-mitrale” – V1: Mainly or purely negative P-wave

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P Waves of LAA Hypertrophy - Ventricular

Multiple criteria exist Included in handout Trust your eyes for size

Hypertrophy - - Ventricular

RVH LVH – Found in validity evaluation – Suggested in first scan of EKG “Big" R wave in V 1 (6-7 mm) – One method (Sokolow) is to Normal pattern: No R in V1 Look at biggest R in V 5 or V 6, plus “Deep” S wave in V 6 (6-7 mm) Biggest S in V 1 or V2 Normal pattern: No S in V6 LVH suggested if > 35mm in adult – Included in differential of RAD

LVH Example What hypertrophy is suggested in V1?

1. None Deepest S: 18 mm 2. LAE 3. RAE

Tallest R: 40 mm 4. LVH 5. RVH

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Basic Cumulative Review

Validity Major Brain Default Rate Rhythm Axis Overload imminent! Hypertrophy Abort!

Poll Question: This EKG suggests Ischemia/Infarction 1. Normal Check all leads for: 2. Anterior MI – Q waves 3. Lateral MI – ST segment changes 4. Septal – T wave changes ischemia 5. Inferolateral Look in groups of leads ischemia

T Waves ST Segment Changes

Usually QRS and T are upright together Differential for ST Depression T waves should be upright in V 2-6 – Ischemia – Can be normally inverted in V 1 – Subendocardial infarct T wave inversion is first sign of ischemia – “Strain” from hypertrophy Peaked T wave is first sign of acute injury or – Drug effect high K+ Digoxin

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Changes of Ischemia ST Segment Changes ST depression T wave inversion Elevation is Acute injury If no Q waves then non-Q wave infarction If associated with Q waves – Likely transmural infarct – Much less common now - thrombolytics

Non Q Wave Infarction Summary of Changes

Repolarization most sensitive part of cycle – Now called – T wave changes are first “Non-ST Elevation MI” or ST segment follows T wave – NSTEMI Q waves can be bad, but also normal!

Dynamic Summary Dynamic Summary

The “Dance” Ischemia: Visual demonstration – T wave inversion, pulls – ST segment down (depression) – If continues, then …

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Dynamic Summary Dynamic Summary

Injury: T wave inverts again (tombstoning) – T wave peaks (hyperacute T wave), which If continues, then… pulls – ST segment up (elevation) Infarction • Represents at risk – If injury continues, then…

Dynamic Summary Dynamic Summary

Infarction: The whole process is a continuum – Q wave appears (irrev cell death) – If continues… – Includes – Q wave enlarges and ST seg returns to – Ischemia baseline – Injury T wave inversion is the last thing to return to – Infarction "normal"

Q/ST changes in Lead Groups (Artery) Septal (LAD): This EKG suggests – Changes in V1-V2 Anterior (LAD): 1. Normal – V3-V4 2. Anterior MI Lateral (Circumflex): 3. Lateral MI – I, aVL, V5-V6 4. Septal ischemia Inferior (RCA or Circumflex): 5. Inferolateral – II, III, aVF ischemia Posterior (RCA):Large R with ST depression V1, V2

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Summary

Validity Captain, she’s gonna blow! – Context – Standardization box – I and aVR Not to worry – R wave progression You now know this stuff – Compare with old EKG

Summary Summary Rate – 300 Rhythm – 150 – Regular or not – 100 – – 75 Sinus or not – 60 – Intervals evaluated – 50 PR – 43 QRS – 37 QT

Summary Summary

Axis Hypertrophy – I and aVF – Atrial – Normal Quadrant or Not (Axis Deviation) Look at P wave in leads II and V 1 – Isoelectric lead next to get degree of axis – Ventricular – Work to give degree measurement! Many criteria exist

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Summary That’s Enough! Ischemia – T wave inversion – ST segment depressed Injury Now, be careful out there! – Peaked T wave (maybe) – ST segment elevated (maybe) Cell death – Q wave forms

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