Electrocardiograms

James Lamberg

Electrical System Overview

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Action Potentials

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12-Lead Positioning

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Values To Memorize
• Inherent Rates
– SA: 60 to 100 – AV: 40 to 60 – Ventricles: 20 to 40

• Normal PRI: 0.12 to 0.20
– 3 to 5 small boxes

• Normal QRS: < 0.12
– Less than 3 small boxes

• Normal QTc: 0.35 to 0.45
– QT < 1/2 RR; QTc = QT / sqrt(RR)

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Calculating Rates
• Count R waves in 6 seconds x 10
– R waves between 2 sets of 3s marks

• Large boxes between R waves / 300
– Small boxes between R waves / 1500

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Standard ECG

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Precordial Leads

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Determining Axis & Rotation
• Axis: Look at Lead I and aVF
– QRS complexes
• • • • Positive: Normal “Leaving”: Left “Reaching”: Right Negative: Indeterminate

– Perpendicular to isoelectric lead

• Rotation: Look at V1 to V6
– V1 or V2 isoelectric: Right – V3 or V4 isoselectric: Normal – V5 or V6 isoelectric: Left

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Axis: Leads I, II, III

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Determining Axis: An Example

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Normal Sinus Rhythm

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Sinus Bradycardia

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Sinus Tachycardia

*

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Sinus Arrhythmia

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Congestive Heart Failure Causes
• FAILURE
– Forgot medication – Arrhythmia, Anemia – Ischemia, Infarction, Infection – Lifestyle (too much salt) – Upregulation of cardiac output (pregnancy, hyperthyroidism) – Renal failure – Embolism (PE)

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First Degree Heart Block

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Second Degree Block Type I

*

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Second Degree Block Type II

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Third Degree Heart Block

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Premature Atrial Contraction

*

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Premature Junctional Contraction

*

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Premature Ventricular Contraction

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Atrial Fibrillation

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Atrial Fibrillation Causes
• THE ATRIAL FIBS
– – – – Thyroid Hypothermia Embolism (PE) Alcohol (“holiday heart”) – Trauma (cardiac contusion) – Recent surgery (post-CABG) – Ischemia – Atrial enlargement – Lone (idiopathic) – Fever, anemia, high-output states – Infarct – Bad values (mitral stenosis) – Stimulants (cocaine, theophylline, amphetamine, caffeine)

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Atrial Flutter

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Atrial Tachycardia

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Atrial Bigeminy & Trigeminy
• Bigeminy

*
• Trigeminy

*

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Supraventricular Tachycardia

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Junctional Escape Rhythm

*

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Junctional Tachycardia

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Ventricular Fibrillation

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Ventricular Tachycardia

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Torsade de Pointes

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Ventricular Bigeminy & Trigeminy
• Bigeminy

• Trigeminy

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Ventricular Asystole

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Bundle Branch Blocks
• Characteristic QRS pattern in lead I, V1, and V6

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The Turn Signal Rule
• Turn-Signal Rule
– – – – QRS >0.12 everywhere Look V1 QRS Find J point Draw a horizontal line

• Triangle pointing up indicates RBBB • Triangle pointing down indicates LBBB

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William Marrow (V1-V6)
• LBBB • RBBB

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Left Bundle Branch Block

*

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Right Bundle Branch Block

*

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Wolff-Parkinson-White
• Pre-excitation
– Bundle of Kent – Delta wave
• Slurred QRS

• Lown-Ganong-Levine
– Bundle of James – Short PR Interval
• < 0.12s

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Sick Sinus Syndrome

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Atrial Hypertrophy

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Atrial Hypertrophy
• P Pulmonale: Right (RAH)

• P Mitrale: Left (LAH)

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Ventricular Hypertrophy
• Right (RVH)
– Right axis deviation and rotation – Tall QRS on right side leads
• (V1, V2, V3)

• Left (LVH)
– Left axis deviation and rotation – Tall QRS on left (V4, V5, V6)

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Left Ventricular Hypertrophy

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Significant Q Waves

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Myocardial Infarction
• Significant Q wave = Necrosis • ST elevation = Injury • T wave inversion = Ischemia

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MI Location

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MI Location

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Anterior Leads

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Lateral Leads

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Inferior Leads

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Pericarditis
– Diffuse ST Elevation – PR Depression

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Pericarditis Causes
• CARDIAC RIND
– Collagen vascular disease – Aortic aneurysm – Radiation – Drugs (hydralazine) – Infections – Acute renal failure – Cardiac infarction – – – – Rheumatic fever Injury Neoplasms Dressler syndrome (MI or surgery)

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Non-STEMI versus STEMI
• Non-STEMI • STEMI

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STEMI Progression

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STEMI Progression

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ST Segment Elevation
• ELEVATION
– Electrolytes – Left bundle branch block – Early repolarization – Ventricular hypertrophy – Aneurysm – Treatment (pericardiocentesis) – Injury (acute MI, contusion) – Osborne waves (hypothermia) – Nonocclusive vasospasm

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ST Segment Depression
• DEPRESSED ST
– – – – – – – – – – – Drooping valve (mitral valve prolapse) Enlargement or LV with strain Potassium loss (hypokalemia) Reciprocal ST depression (inferior MI) Embolism (PE) Subendocardial ischemia Subendocardial infarct Encephalon hemorrhage Dilated cardiomyopathy Shock Toxicity of digitalis, quinidine

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Abnormal T Waves
• Subarachnoid hemorrhage • Cerebral hemorrhage • Cerebral thrombosis

*

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Electrolytes & Drugs
• Hyperkalemia
– High K+ – Peaked T

• Hypokalemia
– Low K+ – Flat T, U Wave

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Electrolytes & Drugs
• Hypercalcemia
– Short QT

• Hypocalcemia
– Long QT

• Dititalis
– Sloping ST

• Quinidine
– Long QT – Notched P

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Brudada Syndrome
• Asian Males • ST Elevation in V1, V2, V3

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Interpretation Example #1

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Interpretation Example #2

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Right Sided ECG

*

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Interpretation Example #3

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Interpretation Example #4

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Interpretation Example #5

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Interpretation Example #6

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Tools of the Trade
• Recommend
– Calipers

• Useful
– Magnifier

• Avoid
– Rulers

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Questions?

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