Transcript Advanced Cardiac Care in the Streets

Advanced Cardiac Care in the Streets
Understanding EKGs
Ray Taylor
Valencia Community College
The Electrical Conduction
System
Notice
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All rights reserved.
Slide show used with permission only for the
purposes of educating emergency medical
providers (EMTs and Paramedics)
No portion of this presentation may be reproduced,
stored in a retrieval system in any form or by any
means (including but not limited to electronic,
mechanical, photocopying etc.) without prior
written permission from the author
The Electrical Conduction System
 Objectives
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1. Identify the location and function of the
following:
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SA Node
Internodal pathways
Bachmann’s Bundle
AV Node
Bundle of His
AV Junction
Bundle Branches
Purkinje Network
The Electrical Conduction System
 Objectives
 2.
Relate the normal path of an impulse
traveling through the heart’s electrical
conduction system
Cardiac Conduction System
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Components
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Sinoatrial Node
Internodal Atrial
Pathways
Bachman’s Bundle
Atrioventricular Node
Atrioventricular
Junction
Bundle of His
Left and Right
Bundle Branches
Purkinje Fibers
The SA Node
 The
Sinoatrial [SA] Node is located
in the upper posterior portion of the right atrial
wall of the heart
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Junction of RA and SVC
pacemaker” of the heart
 Firing rate = 60 to 100 beats per
min.
 “primary
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Depolarization and Myocardial contraction
occurs after impulse leaves SA Node
Internodal Pathways
Internodal pathways receive
the electrical impulse as it exits the SA
Node.
 The
 Anterior,
 Pathways
posterior, and middle pathways
distribute impulse throughout
atria
 Transmit impulse from SA Node to AV
Node
Bachmann’s Bundle
 Bachmann’s
Bundle - a group of
interatrial fibers contained in left atrium
 A subdivision of anterior internodal
tract
 Conducts electrical activity from the SA
Node to the left atrium
The AV Node
Atrioventricular (AV) Node located on floor of right atrium above
tricuspid valve
 Electrical activity delayed 0.05 seconds
 Allows for more complete filling of
ventricles
 Only pathway for atrial electrical
impulses to reach ventricles
 The
 “Gate-Keeper
to the ventricles
The AV Junction
AV Junction is where SA Node
joins Bundle of His
 SA Node fails or slows below normal,
AV junctional tissues initiate
electrical activity
 The
 Secondary
 Discharges
per minute
(escape) Pacemaker
at intrinsic firing rate 40 – 60 beats
The Bundle of His
Bundle of His - conduction pathway that
leads out of AV node
 Lies at top of interventricular septum
 Referred to as the “common bundle”
 Makes electrical connection between atria
and ventricles
 Ability to self-initiate electrical activity at
intrinsic firing rate of 40 to 60 beats
per min.
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Bundle Branches
 Bundle
of His divides into two main
Bundle Branches
 1.
Right Bundle Branch
 Long
and thin
 Extends to apex of right ventricle
 2.
Left Bundle Branch
 Anterior
and posterior fascicles
electrical activity from Bundle of
His to Purkinje Network
 Conduct
Purkinje’s Network
 Purkinje’s
Network - fibers that
spread throughout the ventricles
 Carries impulses directly to ventricular
muscle cells
 Intrinsic firing rate of 20 to 40
beats per min.
Summary of Conduction System
SA node
 Internodal pathways
and Bachman’s bundle
 AV Node
 His Bundle
 Bundle Branches
 Purkinje Network
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Summary of Discharge Rates
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Sinoatrial Node
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AV Junction
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Primary pacemaker with
fastest intrinsic discharge
rate
60 – 100 beats per minute
Secondary pacemaker
40 – 60 beats per minute
Purkinje Fibers
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20 – 40 beats per minute
Thank you!