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ECG Rhythm Interpretation

Module III

Normal Sinus Rhythm

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Course Objectives

To recognize the normal rhythm of the

heart - Normal Sinus Rhythm.

To recognize the 13 most common

rhythm disturbances.

To recognize an acute myocardialinfarction on a 12-lead ECG.

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Learning Modules

ECG Basics

How to Analyze a Rhythm Normal Sinus Rhythm

Heart Arrhythmias

Diagnosing a Myocardial Infarction

Advanced 12-Lead Interpretation

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Normal Sinus Rhythm (NSR)

Etiology: the electrical impulse is

formed in the SA node and conducted

normally.

This is the normal rhythm of the heart;other rhythms that do not conduct via

the typical pathway are called

arrhythmias.

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NSR Parameters

Rate 60 - 100 bpm

Regularity regular P waves normal

PR interval 0.12 - 0.20 s

QRS duration 0.04 - 0.12 s

Any deviation from above is sinus

tachycardia, sinus bradycardia or an

arrhythmia

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Arrhythmia Formation

Arrhythmias can arise from problems in

the:

Sinus node

Atrial cells

AV junction Ventricular cells

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SA Node Problems

The SA Node can:

fire too slow

fire too fast

Sinus Bradycardia

Sinus Tachycardia

Sinus Tachycardia may be an appropriate

response to stress.

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Atrial Cell Problems

Atrial cells can:

fire occasionally

from a focus

fire continuouslydue to a looping

re-entrant circuit

Premature Atrial

Contractions (PACs)

Atrial Flutter

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Teaching Moment

A re-entrant

pathway occurs

when an impulseloops and results

in self-

perpetuatingimpulse

formation.

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Atrial Cell Problems

Atrial cells can also:

fire continuously

from multiple focior

fire continuously

due to multiplemicro re-entrant

wavelets

Atrial Fibrillation

Atrial Fibrillation

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Teaching Moment

Multiple micro re-

entrant wavelets

refers to wandering

small areas ofactivation which

generate fine chaotic

impulses. Collidingwavelets can, in turn,

generate new foci of

activation.

Atrial tissue

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AV Junctional Problems

The AV junction can:

fire continuously

due to a looping

re-entrant circuit

block impulses

coming from the

SA Node

Paroxysmal

Supraventricular

Tachycardia

AV Junctional Blocks

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Ventricular Cell Problems

Ventricular cells can:

fire occasionally

from 1 or more foci

fire continuously

from multiple foci

fire continuously

due to a looping

re-entrant circuit

Premature Ventricular

Contractions (PVCs)

Ventricular Fibrillation

Ventricular Tachycardia

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End of Module III

Normal Sinus Rhythm

Proceed to Module III Practice Quizon WebCT

Thenproceed to module IVa

http://module_4a.ppt/http://module_4a.ppt/