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Electrocardiography A Brief Overview of ECG Interpretation

Electrocardiography A Brief Overview of ECG Interpretation

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Page 1: Electrocardiography A Brief Overview of ECG Interpretation

Electrocardiography

A Brief Overview of ECG Interpretation

Page 2: Electrocardiography A Brief Overview of ECG Interpretation

Normal to Abnormal

• Only way to understand abnormal is to first look at the “normal”.

• First: looking at cardiac electrical conduction.

Page 3: Electrocardiography A Brief Overview of ECG Interpretation

Conduction System

Sinoatrial Node

Atrioventricular Node

Bundle of His

Bundle Branches Perkinje Fibres

Page 4: Electrocardiography A Brief Overview of ECG Interpretation

Conduction System

• Sinoatrial Node (60-80 bpm)

• Atrioventricular Node (40-60 bpm)

• Bundle of His (20-40 bpm)

• Bundle Branches

• Purkinje fibres

• Cardiac Cells

Page 5: Electrocardiography A Brief Overview of ECG Interpretation

Normal Conduction

• SA node starts action

• Accepted by AV node, starts inferior action

• Passes to bundle of His, down Purkinje fibres

• Action potential restarts

Page 6: Electrocardiography A Brief Overview of ECG Interpretation

Cardiac CellRegular Muscle cells many moreNuclei per cell, whereas cardiacMuscle cells only have one.

Much more like smooth muscle,Under involuntary control.

Page 7: Electrocardiography A Brief Overview of ECG Interpretation

Cardiac Cell

Page 8: Electrocardiography A Brief Overview of ECG Interpretation

Muscle Cell

Page 9: Electrocardiography A Brief Overview of ECG Interpretation

Conductivity

• Contractile and Conductive cells

• Focused impulse is generated (a pacemaker of any other site) then surrounding tissue will rhythmically contract.

• Bad when not starting at node.

Page 10: Electrocardiography A Brief Overview of ECG Interpretation

Normal ECG

Page 11: Electrocardiography A Brief Overview of ECG Interpretation

Normal ECG

Page 12: Electrocardiography A Brief Overview of ECG Interpretation

Dysrhythmias

• Look at P Wave

• Look at QRS complex

• Look at T Wave

• Look for U Waves

Page 13: Electrocardiography A Brief Overview of ECG Interpretation

Rhythm Rate

• In order to tell what the rate of the heart is from the ECG:

• Count the # of QRS complexes in a six second strip and multiply by ten.

Page 14: Electrocardiography A Brief Overview of ECG Interpretation

Dysrhythmias

• Rate

• P Waves (present, inverted, absent, retrograde, ratio)

• PR Interval (5 small squares)

• QRS (3 small squares)

• Rhythm (regular/irregular)

Page 15: Electrocardiography A Brief Overview of ECG Interpretation

Interpret me!

Page 16: Electrocardiography A Brief Overview of ECG Interpretation

Now me!

Page 17: Electrocardiography A Brief Overview of ECG Interpretation

Heart Disease

• #1 killer in Canada

Page 18: Electrocardiography A Brief Overview of ECG Interpretation

Blocked Coronary Artery

• depending on the amount of damage, conductive system may be impaired.

• electrical impulses do not travel across dead tissue.

Page 19: Electrocardiography A Brief Overview of ECG Interpretation

Defibrillation

• Reboot the computer

Page 20: Electrocardiography A Brief Overview of ECG Interpretation

Defibrillation

• Definition - the application of an external electrical shock to the heart muscle which terminates the electrical activity of the heart. This allows the natural pacemakers of the heart to restore normal rhythm.

• Time from collapse to defibrillation is critical factor to survival

Page 21: Electrocardiography A Brief Overview of ECG Interpretation

Ventricular Tachycardia

Page 22: Electrocardiography A Brief Overview of ECG Interpretation

Ventricular Fibrillation

Page 23: Electrocardiography A Brief Overview of ECG Interpretation

Non-Shockable Rhythms

Page 24: Electrocardiography A Brief Overview of ECG Interpretation

12 Lead

• Normally look at Lead II (over Left shoulder)

• Sometimes need to look at more aspects of heart

• Used to diagnose myocardial infarction, other cardiac dysrhythmias

• Looks at 12 Different aspects of the heart

Page 25: Electrocardiography A Brief Overview of ECG Interpretation

12 Lead

Page 26: Electrocardiography A Brief Overview of ECG Interpretation

Questions?