ECG Interpretations

Course Objectives

• Proper Lead Placements

• Review the ECG print paper

• Review the mechanics of the Myocardium

• Review basics of ECG Rhythms

How Leads Work

• The ECG Leads we use are Bipolar

• When an electrical impulse moves towards the (+) lead

• Displays as an Upward Deflection

• When an electrical impulse moves

toward the (-) lead

• Displays as a Downward Deflection

Lead II is displayed on the monitor because it shows the most (+) moving activity

ECG Lead Placement

• “Limb Leads” • If 3 Leads (RA, LA, LL) • If 4 Leads (RA, LA, LL, RL)

• RA is ground for all leads (Including the 12 leads) • If there is excess artifact or difficulty with display

• Replace the RA Lead with a fresh sticker

• Place Leads on muscle, not over bone

• When you can: Place the Leads on the Torso of the Patient

ECG Lead Placement

Remember: “Clouds over Grass, Smoke over Fire”

RA (White) – Negative (-) LA (Black) – Negative (-) RL (Green) – Positive (+) LL (Red) - Positive (+)

Breakdown of the Cardiac Rhythm Strip:

HOW TO READ THE PRINTOUT…….. ECG interpretations

The ECG Paper

• Horizontally (Time) – One small box - 0.04 sec – One large box - 0.20 sec

• Vertically (Voltage)

– One large box - 0.5 mV

The ECG Paper (cont.)

• Every 3 seconds (15 large boxes) is marked by a vertical line.

– ECG Interpretations are based on 6 seconds

3 sec 3 sec

THE MECHANICS OF THE MYOCARDIUM………

ECG interpretations

Pacemakers of the Heart

• SA Node - Dominant pacemaker with an intrinsic rate of 60 - 100 beats/minute.

• AV Node - Back-up pacemaker with an intrinsic rate of 40 - 60 beats/minute.

• Ventricular cells - Back-up pacemaker with an intrinsic rate of 20 - 45 bpm.

Impulse Conduction & the ECG

Sinoatrial node

AV node

Bundle of His

Bundle Branches

Purkinje fibers

The “PQRST”

• P wave - Atrial depolarization

• QRS - Ventricular depolarization

• T wave - Ventricular repolarization

The Atria repolarizes at the same time that the Ventricles depolarize

MEASUREMENTS OF ECG INTERPRETATIONS……….

ECG interpretations

Option 1 Step 1: Calculate Rate

• Count the Number of complete QRS complexes in a 6 second rhythm strip, then multiply by 10. • Reminder: all rhythm strips in the modules are 6

seconds in length.

What is the Rate on this Strip? 9 x 10 = 90 bpm

3 sec 3 sec

Option 2 Step 1: Calculate Rate

– Find an R wave that lands on a bold line. – Count the number of large boxes to the next R wave. If the

second R wave is 1 large box away the rate is 300, 2 boxes - 150, 3 boxes - 100, 4 boxes - 75, etc. (cont.)

R wave

Option 2 Step 1: Calculate Rate

– Memorize the sequence: 300 - 150 - 100 - 75 - 60 - 50

What is the Rate on this Strip?

300

150

100

75

60

50

Approx. 1 box less than 100 = 95 bpm

Step 2: Determine regularity

• Look at the R-R distances (using a caliper or markings on a pen or paper).

• Regular (are they equal distance apart)? Occasionally irregular? Regularly irregular? Irregularly irregular?

R R

Step 3: Assess the P waves

• Are P waves present? • Do the P waves all look the same? • Do the P waves occur at a regular rate? • Is there one P wave before each QRS complex?

Normal P waves with 1 P wave for every QRS

Step 4: Determine PR interval

• Normal: 0.12 - 0.20 seconds. (3 - 5 boxes)

Step 5: QRS duration

• Normal: 0.04 - 0.12 seconds. (1 - 3 boxes)

PUTTING IT ALL TOGETHER………. ECG interpretations

Rhythm Analysis

Step 1: Calculate rate. Step 2: Determine regularity. Step 3: Assess the P waves. Step 4: Determine PR interval. Step 5: Determine QRS duration.

Normal Sinus Rhythm (NSR)

• Rate 60 - 100 bpm • Regularity regular • P waves Before each QRS Complex • PR interval 0.12 - 0.20 sec • QRS duration 0.04 - 0.12 sec

Sinus Rhythms:

• Sinus Tachycardia

• Sinus Bradycardia

• Sinus Arrhythmia

Sinus Tachycardia

• Rate between 100 and 150 bpm • Regularity regular • P waves before each QRS Complex • PR interval 0.12 - 0.20 sec • QRS duration 0.04 - 0.12 sec

Remember: sinus tachycardia can be a response to physical or psychological

stress, not a primary arrhythmia.

Sinus Bradycardia

• Rate less than 60 bpm • Regularity regular • P waves before each QRS Complex • PR interval 0.12 - 0.20 sec • QRS duration 0.04 - 0.12 sec

Sinus Arrhythmia

• Rate 60 - 100 bpm • Regularity irregular • P waves normal • PR interval 0.12 - 0.20 sec • QRS duration 0.04 - 0.12 sec

Can be related to respirations, common in pediatrics

Atrial Rhythms

• Wandering Atrial Pacemaker • Atrial Tachycardia • Atrial Flutter • Atrial Fibrillation

Wandering Pacemaker

• Rate 40-60 bpm • Regularity slightly irregular • P waves change from beat to beat, may disappear completely

• PR interval 0.12 - 0.20 sec • QRS duration 0.04 - 0.12 sec

Atrial Tachycardia

• Rate more than 100 bpm • Regularity regular • P waves normal, flat or inverted • PR interval varies • QRS duration 0.04 - 0.12 sec

Atrial Flutter

• Rate Ventricle Rate - normal Atrial Rate - 250-320 bpm

• Regularity regular • P waves flutter wave – Multiple

per each QRS Complex • PR interval not measurable • QRS duration 0.04 - 0.12 sec

(Turning the strip upside down may make the saw tooth pattern more prominent)

Atrial Fibrillation

• Rate Atrial Rate – can’t be counted

Ventricular Rate - varies • Regularity irregularly irregular • P waves not distinguishable • PR interval not measurable • QRS duration 0.04 - 0.12 sec

Junctional Rhythms

• Junctional Escape • Junctional Bradycardia • Accelerated Junctional • SVT

Junctional Escape

• Rate 40-60 bpm • Regularity regular • P waves inverted or flat • PR interval < 0.12 - if before the QRS Complex

• QRS duration usually <0.12 sec, but can be greater

Junctional Bradycardia

• Rate <40 bpm • Regularity regular • P waves inverted or flat • PR interval < 0.12 sec • QRS duration usually <0.12 sec, but can be greater

Accelerated Junctional

• Rate 60 - 100 bpm • Regularity regular • P waves inverted or flat • PR interval < 0.12 - if before the QRS Complex

• QRS duration usually <0.12 sec, but can be greater

Junctional Tachycardia

• Rate more than 100 bpm • Regularity regular • P waves inverted or flat • PR interval 0.12 - 0.20 sec • QRS duration 0.04 - 0.12 sec

Supraventricular Tachycardia (SVT)

• Rate greater than 150 bpm • Regularity regular • P waves unable to be read • PR interval buried in previous QRS Complex • QRS duration 0.04 - 0.12 sec

Blocks

• 10 HB + Underlying Rhythm • 20 Type I - Wenkebach • 20 Type II - Classical • 30 degree HB

1st Degree AV Block

• Prolonged conduction delay in the AV node or

Bundle of His. • PRI will be greater than 0.20 • There will be one P wave in front of every QRS

Complex • The underlying rhythm is part of the interpretation

20 HB Mobitz I - Wenckebach

• Rate Atrial Rate – normal Ventricular Rate – Bradycardic

• Regularity regular • P waves normal • PR interval progressively longer until

the QRS is missed – then recaptures

• QRS duration 0.04 - 0.12 sec

20 HB Block, Type II - Classical

• Rate Atrial Rate – normal Ventricular Rate – Bradycardic • Regularity regular • P waves ratio of 2:1, 3:1 (P waves to QRS) • PR interval normal or prolonged when followed by a

QRS Complex (P-R Interval will always be the same)

• QRS duration 0.04 - 0.12 sec - P wave conduction is blocked in a consistent repeating pattern

3rd Degree AV Block

• Rate Atrial Rate – normal Ventricular Rate – Bradycardic Rate • Regularity regular from P to P or QRS to QRS • P waves unrelated to QRS Complex • PR interval unrelated to QRS Complex • QRS duration slower than 0.12 seconds

– The P waves are completely blocked in the AV junction; QRS complexes originate independently from below the AV junction.

Differentiating The Heart Blocks

Heart Block R to R PR interval

20 Type I – Wenckebach

Irregular - Dropped QRS

Irregular – longer, longer, longer

20 Type II - Classical

Regular if consistent degree of block

Regular for PR interval; just more P’s than QRS

3rd degree - complete Regular Irregular – no pattern

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• Look at the R to R intervals – Are they regular or not

• Look at the PR intervals – Are they consistent? If not, is there a pattern

Differentiating The Heart Blocks

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Differentiating The Heart Blocks

Comparing Heart Blocks

Ectopic Beats

• Premature Atrial Contraction (PAC)

• Premature Junctional Contraction (PJC)

• Premature Ventricular Contraction (PVC)

– Uni-focal – Multi-focal

Premature Atrial Contractions (PAC)

• Etiology: Excitation of an atrial cell forms an

impulse that is then conducted normally through the AV node and ventricles.

Premature Junctional Contractions (PJC)

• Etiology: Excitation of cells in the AV Node. A pause is dependent on if the SA Node is depolarized when the impulse occurs.

Premature Ventricular Contraction (PVC)

– Ectopic beats originate in the ventricles resulting in wide and bizarre QRS complexes.

– Compare multiple premature beats:

• When multiple PVCs look alike, they are called “uniform”

• When multiple PVCs look different, they are called “multifocal”

Unifocal PVC

Multifocal PVC

PVC Patterns

• Bigeminy: – Every other beat is a PVC

• Trigeminy: – Every third beat is a PVC

• Quadgeminy – Every fourth beat is a PVC

Run of PVCs

If 3 or more PVCs occur in a row: This is a Run of V-Tach (Ventricular Tachycardia)

Ventricular Rhythms

• Wolf Parkinson White (WPW) • Ventricular Tachycardia (V-Tach) • Torsade de pointes • Ventricular Fibrillation (V-Fib) • Asystole

Wolf Parkinson White (WPW)

– Congenital defect in conduction system – Presence of abnormal electrical pathway that can cause

tachycardia – Episodes often begin occurring in teens and early 20’s

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Normal Conduction WPW Conduction

Wolf Parkinson White (WPW)

• The pacemaker impulse bypasses the AV Node • Rate: 60-100 bpm • Rhythm: regular • P wave: less than 0.12 sec • QRS: > .12 seconds (wide and bizarre)

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Only Rhythm with Delta Wave

Ventricular Tachycardia (monomorphic)

• Ventricular cells fire continuously due to a looping re-entrant circuit • Rate usually regular, 100 - 250 bpm • P wave: absent • QRS: complexes bizarre, > .12 • Rhythm: usually regular

Ventricular Tachycardia (polymorphic)

• Ventricular cells fire continuously due to a looping re-entrant circuit from multiple foci

• Rate usually regular, 100 - 250 bpm • P wave: may be absent, inverted or retrograde • QRS: complexes bizarre, > .12 • Rhythm: usually regular

Torsade de Pointes A Multifocal V-Tach

• Escape rhythm (safety mechanism) to prevent ventricular standstill • Bundle of HIS/Purkinje Fiber pacemaker take over • Rhythm: varies from beat to beat • P wave: absent • QRS: > .12 seconds (wide and bizarre)

*Can be caused by mixture of antiarrhythmic drugs and non-sedating antihistamines,

anti fungal meds and certain antibiotics * Can be seen in alcoholic, anorexia and/or bulimic patients

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Ventricular Fibrillation

• Rhythm: irregular (coarse or fine), wave form varies in size and shape • Fires continuously from multiple foci • No organized electrical activity • No cardiac output

Asystole

• Ventricular standstill, no electrical activity, no cardiac output – no pulse! • Remember! No defibrillation with Asystole • Rate: absent due to absence of ventricular activity.

– Occasional P wave may be identified – Not productive

Other Rhythms

• Idioventricular • Accelerated Idioventricular • Paced • PEA

Idioventricular Rhythm

• Escape rhythm (safety mechanism) to prevent ventricular standstill • HIS/Purkinje system takes over as the heart’s pacemaker • Rhythm: regular • Rate: 20-40 bpm • P wave: absent • QRS: > .12 seconds (wide and bizarre)

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Accelerated Idioventricular Rhythm

• Escape rhythm (safety mechanism) to prevent ventricular standstill • Bundle of HIS/Purkinje Fiber system takes over as the heart’s pacemaker • Rhythm: regular • Rate: 60-100 bpm • P wave: absent • QRS: > .12 seconds (wide and bizarre)

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Paced Rhythm

• Man made mechanical pacing device • Rhythm: regular if continuous firing Irregular if pacing on demand • Rate: Based on what is programmed • P wave: dependent on where pacer is originating from • QRS: > .12 seconds (wide and bizarre) The only thing to identify is that it is a “Paced Rhythm”

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Pulseless Electrical Activity (PEA)

• Pick any rhythm that we have discussed and remove the pulse

• This is only electrical activity with no mechanical function

• That is why we treat the patient, not the monitor.

• Consider the H’s and T’s to improve the patient’s out come: - Hypoxia - Hypovolemia - Tension Pneumothorax - Hypothermia - Hypo/Hyperkalemia - Tamponade – Cardiac - Hydrogen Ion (Acidosis) - Thrombosis – Pulmonary - Thrombosis - Cardiac

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NO PULSE

INTERPRETATIONS……… ECG interpretations

Normal Sinus Rhythm

Atrial Fibrillation

Is the patient stable or unstable? Patients can walk around in this rhythm with no problems Watch for medication hx to include: Coumadin, Prodaxa, Eliquis, Xarelto or Lovenox

Sinus Rhythm w/ Run of V-Tach

Is the patient stable or unstable? Are there multiple occurrences? Interventions: ASA (ACS SOP) and Amiodarone

20 HB – Mobitz II (Classical)

Is the patient stable or unstable Interventions: Dopamine, TCP

Sinus Rhythm w/10 Heart Block

Not Normal Sinus Rhythm w/10 Heart Block

Monomorphic V-Tach

Is the patient stable or unstable? Intervention: Amiodarone 150mg in 50 ml 0.9 NS drip Be ready for Synchronized Cardioversion

Torsades de Pointes

Is the patient stable or unstable? Intervention: Magnesium 2 Gm w/16 ml 0.9 NS over 5 min or you may get the 2 Gm in 40 ml bag. Be ready for Defibrillation

Junctional Escape

Is the patient stable or unstable? Interventions: Atropine, Dopamine, TCP

Artificial Paced Rhythm

Is the patient stable or unstable?

Pulseless Electrical Activity (PEA)

NO PULSE

Start CPR Consider H’s and T’s Interventions: Epinephrine, Possibly Sodium Bicarbonate

REVIEW……………..

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Review…………

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For every strip we look at: Rate Regularity Determine P waves Measure PR interval

Determine QRS duration

Pacemaker Rates: SA Node – Dominant pacemaker: 60 – 100 bpm

AV Node – Back-up pacemaker: 40 - 60 bpm

Ventricular cells - Back-up pacemaker: 20 - 45 bpm

Review………..

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Each small square is 0.04 seconds and a large box is 0.20 seconds

P wave - Atrial depolarization QRS – Ventricular depolarization T wave - Ventricular repolarization

* The Atria repolarizes at the same time that the Ventricles depolarize

Questions?

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