Davis Ecg Notes

215

description

A book for ECG review

Transcript of Davis Ecg Notes

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    2142_FM_ii-vi.qxd 9/12/09 2:39 PM Page ii

  • ECGECGNotesNotesInterpretation and Management Guide

    Shirley A. Jones, MS Ed, MHA, EMT-P

    Purchase additional copies of this book at yourhealth science bookstore or directly from F.A. Davisby shopping online at www.fadavis.com or by calling 800-323-3555 (US) or 800-665-1148 (CAN)

    A Daviss Notes Book

    2nd Edition

    2142_FM_ii-vi.qxd 9/12/09 2:39 PM Page iii

  • F. A. Davis Company1915 Arch StreetPhiladelphia, PA 19103www.fadavis.com

    Copyright 2010 by F. A. Davis Company

    All rights reserved. This book is protected by copyright. No part of it may be reproduced, storedin a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher.

    Printed in China by Imago

    Last digit indicates print number: 10 9 8 7 6 5 4 3 2 1

    Publisher, Nursing: Lisa B. DeitchDirector of Content Development: Darlene D. PedersenProject Editor: Christina C. BurnsCover Design: Carolyn OBrienReviewers: Jill M. Mayo, RN, MSN, ACLS; Jill Scott, RN, MSN, CCRN; Patricia Sweeney, MS,CRNP, FNP, BC; Barbara Tacinelli, RN, MA

    As new scientific information becomes available through basic and clinical research, recom-mended treatments and drug therapies undergo changes. The author(s) and publisher have doneeverything possible to make this book accurate, up to date, and in accord with accepted stan-dards at the time of publication. The author(s), editors, and publisher are not responsible forerrors or omissions or for consequences from application of the book, and make no warranty,expressed or implied, in regard to the contents of the book. Any practice described in this bookshould be applied by the reader in accordance with professional standards of care used in regardto the unique circumstances that may apply in each situation. The reader is advised always tocheck product information (package inserts) for changes and new information regarding doseand contraindications before administering any drug. Caution is especially urged when usingnew or infrequently ordered drugs.

    Authorization to photocopy items for internal or personal use, or the internal or personal use ofspecific clients, is granted by F. A. Davis Company for users registered with the CopyrightClearance Center (CCC) Transactional Reporting Service, provided that the fee of $.25 per copy ispaid directly to CCC, 222 Rosewood Drive, Danvers, MA 01923. For those organizations that havebeen granted a photocopy license by CCC, a separate system of payment has been arranged. Thefee code for users of the Transactional Reporting Service is: 8036-2142-6/10 0 $.25.

    2142_FM_ii-vi.qxd 9/12/09 2:39 PM Page iv

  • BASICS ECGS

    TOOLS

    12-LEAD MEDS SKILLS CPR ACLS PALS

    HIPAA Compliant OSHA Compliant

    Waterproof and ReusableWipe-Free Pages

    Write directly onto any page of ECG Notes 2ewith a ballpoint pen. Wipe old entries off

    with an alcohol pad and reuse

    TEST STRIPS

    2142_FM_ii-vi.qxd 9/12/09 2:39 PM Page v

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    ECG Success: Exercises in ECG InterpretationISBN-13: 978-0-8036-1577-9

    For a complete list of Daviss Notes and other titles for health care providers, visit www.fadavis.com.

    2142_FM_ii-vi.qxd 9/12/09 2:39 PM Page vi

  • Anatomy of the Heart

    The heart, a fist-sized muscular organ located in the mediastinum, is thecentral structure of the cardiovascular system. It is protected by the bonystructures of the sternum anteriorly, the spinal column posteriorly, and therib cage. The heart is roughly conical, with the base of the cone at the topof the heart and the apex (the pointed part) at the bottom. It is rotatedslightly counterclockwise, with the apex tipped anteriorly so that the backsurface of the heart actually lies over the diaphragm.

    1

    BASICS

    Location of the heart

    Clinical Tip: The cone-shaped heart has its tip (apex) just above thediaphragm to the left of the midline. This is why we may think of the heartas being on the left sidethe strongest beat can be heard or felt there.

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  • BASICS

    2

    Layers of the Heart

    The heart is composed of several different layers of tissue. Surrounding theheart itself is a protective sac called the pericardium. This double-walled sachas an inner, serous (visceral) layer and an outer, fibrous (parietal) layer.Between these layers is the pericardial cavity, which contains a smallamount of lubricating fluid to prevent friction during heart contraction. Thelayers of the heart wall itself include the epicardium, or outermost layer; themyocardium, the thick middle layer of cardiac muscle; and the endocardium,the smooth layer of connective tissue that lines the inside of the heart.

    EndocardiumParietalpericardiumMyocardium(heart muscle)

    Epicardium(visceral pericardium)

    Fibrous pericardium(pericardial sac)

    Pericardial cavityLayers of the heart

    Clinical Tip: The pericardial cavity contains a small amount of lubricat-ing fluid to prevent friction during heart contraction.

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  • Heart Valves

    Properties of Heart Valves Fibrous connective tissue prevents enlargement of valve openings

    and anchors valve flaps. Valve closure prevents backflow of blood during and after contraction.

    3

    BASICS

    Pulmonary semilunarvalve

    Aortic semilunarvalve Tricuspid

    valve

    Fibrousskeleton

    Mitral valve

    Posterior

    Coronary artery

    Superior view with atria removed

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  • BASICS

    4

    Heart C

    ham

    bers an

    d G

    reat Vessels

    The heart is a hollow m

    uscle with an internal skeleton of connective tissue that creates four separate cham

    bers.The superior cham

    bers of the heart are the right and left atria. Their primary function is to collect blood as it

    enters the heart and to help fill the lower cham

    bers. The more thickly m

    uscled lower cham

    bers of the heart arethe ventricles. These are the prim

    ary pumping cham

    bers, the left having a thicker myocardial layer than the right.

    Brachiocephalic

    artery

    Superior ven

    a ca

    va

    Left comm

    on carotid arteryLeft subcla

    vian arteryAortic arch

    Right

    pulmonary artery

    Right

    p u lmo n a ry v e in s

    Right atrium

    Inferior ve

    na

    cava

    Tricuspidvalve

    Pu lmo n a ry

    s em

    ilu n a r v a lv e

    Left pulmonary artery

    Left atriumL e ft p u lm

    o n a ry v e in sM

    itra l v a lv eL e ft v e

    n tric leAortic sem

    ilunarvalveInterve

    ntricularseptum

    Apex

    Chordaetendineae

    Right

    ventricle

    Papi l lary

    mu

    scl esH

    eartAn

    terior sectio

    n (arro

    ws sh

    ow

    directio

    n o

    f blo

    od

    flow

    )

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  • Co

    ron

    ary Arteries an

    d V

    eins

    Th

    e coro

    nary arteries an

    d vein

    s pro

    vide b

    loo

    d to

    the h

    eart mu

    scle and

    the electrical co

    nd

    uctio

    n sys-

    tem. T

    he left an

    d rig

    ht co

    ron

    ary arteries are the first to

    bran

    ch o

    ff the ao

    rta, just ab

    ove th

    e leafletso

    f the ao

    rtic valve.

    5

    BASICS

    AortaLeft coronary artery

    Anteriordescending bra

    nch Coronary sin

    us

    Posterior

    arte ry a n d

    v e in

    Small

    cardiac vein

    Right coronary artery

    AB

    Circumfle

    x branch

    Great cardiac

    vein

    Right coronary vein

    (A) A

    nterio

    r view(B

    ) Po

    sterior view

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  • Anatomy of the Cardiovascular System

    The cardiovascular system is a closed system consisting of the heart andall the blood vessels. Arteries and veins are connected by smaller struc-tures that transport substances needed for cellular metabolism to bodysystems and remove the waste products of metabolism from those sametissues. Arteries carry blood away from the heart and, with the exceptionof the pulmonary arteries, transport oxygenated blood. Veins move bloodtoward the heart. With the exception of the pulmonary veins, they carryblood that is low in oxygen and high in carbon dioxide.

    BASICS

    6

    Tunicaexterna

    External elasticlamina Tunica

    media

    Internal elasticlamina Endothelium (lining)

    Artery ArterioleEndothelial

    cellsSmoothmuscle

    Precapillarysphincter

    Capillary

    Blood flowVenule

    Vein

    Valve

    Tunicaintima

    Tunicaexterna

    Tunicamedia

    Blood vesselsCross-section

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  • Cardiovascular SystemMajor Arteries

    7

    BASICS

    OccipitalInternal carotid

    VertebralBrachiocephalic

    Aortic arch

    MaxillaryFacialExternal carotid

    Common carotidSubclavian

    AxillaryPulmonary

    CeliacLeft gastricHepaticSplenic

    Superiormesenteric

    Abdominal aortaRight common

    iliacInternal iliacExternal iliac

    Femoral

    Popliteal

    Anterior tibial

    Posterior tibial

    IntercostalBrachialRenal

    GonadalInferior mesentericRadialUlnarDeep palmar arch

    Superficialpalmar arch

    Deep femoral

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  • BASICS

    8

    Cardiovascular SystemMajor Veins

    Superior sagittal sinusInferior sagittal sinusStraight sinusTransverse sinusVertebral

    External jugularInternal jugular

    SubclavianBrachiocephalic

    PulmonaryHepaticHepatic portalLeft gastric

    RenalSplenicInferiormesentericInternal iliac

    Femoral

    External iliac

    Great saphenous

    Popliteal

    Small saphenous

    Anterior tibial

    Anterior facial

    Superior vena cava

    AxillaryCephalic

    HemiazygosIntercostal

    Inferior vena cavaBrachial

    BasilicGonadal

    Superiormesenteric

    Dorsal arch

    Volar digital

    Dorsal arch

    Common iliac

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  • Properties of Cardiac Cells

    Property AbilityAutomaticity Generates electrical impulse independently, without

    involving the nervous system.Excitability Responds to electrical stimulation.Conductivity Passes or propagates electrical impulses from cell to cell.Contractility Shortens in response to electrical stimulation.

    Mechanics of Heart Function

    Process ActionCardiac Sequence of events in 1 heartbeat. Blood is pumpedcycle through the entire cardiovascular system.Systole Contraction phaseusually refers to ventricular contraction.Diastole Relaxation phasethe atria and ventricles are filling. Lasts

    longer than systole.Stroke Amount of blood ejected from either ventricle in a single volume contraction. Starling's Law of the Heart states that the degree (SV) of cardiac muscle stretch can increase the force of ejected

    blood. More blood filling the ventricles increases SV. Cardiac Amount of blood pumped through the cardiovascular output (CO) system per min. CO = SV x Heart rate (HR)

    Physiology of the Heart

    Normal blood flow through the heart begins at the right atrium, which receivessystemic venous blood from the superior and inferior venae cavae. Bloodpasses from the right atrium, across the tricuspid valve, to the right ventricle.It is then pumped across the pulmonary valve into the pulmonary arteries.

    Outside the heart, the left and right pulmonary arteries distribute blood tothe lungs for gas exchange in the pulmonary capillaries. Oxygenated bloodreturns to the left atrium through the left and right pulmonary veins. Afterpassing across the mitral valve, blood enters the left ventricle, where it ispumped across the aortic valve, through the aorta, into the coronary arteriesand the peripheral circulation.

    9

    BASICS

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  • BASICS

    10

    Systolic and Diastolic Phases in the Heart

    Left atrium

    Pulmonaryartery

    Aorta

    Diastole

    Atrial systolic phase Ventricular systolic phase

    PulmonaryveinSuperior

    vena cava

    Right atrium

    Pulmonaryvalve

    Tricuspidvalve

    Right ventricle

    Inferiorvena cava

    Aortic valveMitral valveLeft ventricle

    Septum

    Papillarymuscle

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  • 11

    BASICS

    Electrical Conduction System of the Heart

    Electrophysiology

    Structure Function and LocationSinoatrial (SA or sinus) Dominant pacemaker of the heart, located in node upper portion of right atrium. Intrinsic rate

    60100 bpm.Internodal pathways Direct electrical impulses between the SA and

    AV nodes and spread them across the atrialmuscle.

    Atrioventricular (AV) Part of the AV junctional tissue, which includes node some surrounding tissue plus the connected bun-

    dle of His. The AV node slows conduction, creatinga slight delay before electrical impulses are carriedto the ventricles. The intrinsic rate is 4060 bpm.

    Bundle of His At the top of the interventricular septum, this bun-dle of fibers extends directly from the AV nodeand transmits impulses to the bundle branches.

    Left bundle branch Conducts electrical impulses to the left ventricle. Right bundle branch Conducts electrical impulses to the right ventricle. Purkinje system The bundle branches terminate with this network of

    fibers, which spread electrical impulses rapidlythroughout the ventricular walls. The intrinsic rate is 2040 bpm.

    Bundle of His

    Left bundlebranch

    Purkinjefibers

    Right bundlebranch

    AV Node

    SA NodeInternodalpathways

    Conduction system of the heart

    Continued

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  • Electrophysiology

    Action EffectDepolarization The electrical charge of a cell is altered by a shift of

    electrolytes on either side of the cell membrane. Thischange stimulates muscle fiber to contract.

    Repolarization Chemical pumps re-establish an internal negativecharge as the cells return to their resting state.

    Electrical Conduction System of the Heartcontd

    BASICS

    12

    The Depolarization Process

    A

    B

    C

    D

    (A) A single cell has depolarized. (B) A wave propagates from cell to cell. (C)Wave propagation stops when all cells are depolarized. (D) Repolarizationrestores each cell's normal polarity.

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  • Progression of Depolarization Through the Heart

    13

    BASICS

    + +++

    + ++++

    ++

    ++

    ++

    ++

    +

    + +

    +

    +

    ++

    ++

    SANode

    Atrialdepolarization

    Apicaldepolarization

    Left ventriculardepolarization

    Septaldepolarization

    AVNode

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  • Clinical Tip: Mechanical and electrical functions of the heart are influ-enced by proper electrolyte balance. Important components of this balanceare sodium, calcium, potassium, and magnesium.

    BASICS

    14

    Correlation of Depolarization and Repolarization With the ECG

    R

    P T

    QS

    Ventriculardepolarization

    Ventricularrepolarization

    Atrialdepolarization

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  • The Electrocardiogram (ECG)

    The body acts as a giant conductor of electrical current. Electrical activity thatoriginates in the heart can be detected on the body's surface through anelectrocardiogram (ECG). Electrodes are applied to the skin to measure volt-age changes in the cells between the electrodes. These voltage changes areamplified and visually displayed on an oscilloscope and graph paper.

    An ECG is a series of waves and deflections recording the heart'selectrical activity from a certain "view."

    Many views, each called a lead, monitor voltage changes betweenelectrodes placed in different positions on the body.

    Leads I, II, and III are bipolar leads and consist of two electrodes ofopposite polarity (positive and negative). The third (ground) electrodeminimizes electrical activity from other sources.

    Leads aVR, aVL, and aVF are unipolar leads and consist of a singlepositive electrode and a reference point (with zero electrical potential)that lies in the center of the heart's electrical field.

    Leads V1V6 are unipolar leads and consist of a single positive electrodewith a negative reference point found at the electrical center of the heart.

    An ECG tracing looks different in each lead because the recordedangle of electrical activity changes with each lead. Different anglesallow a more accurate perspective than a single one would.

    The ECG machine can be adjusted to make any skin electrode positiveor negative. The polarity depends on which lead the machine isrecording.

    A cable attached to the patient is divided into several different-coloredwires: three, four, or five for monitoring purposes, or ten for a 12-lead ECG.

    Incorrect placement of electrodes may turn a normal ECG tracing intoan abnormal one.

    Clinical Tip: It is important to keep in mind that the ECG shows onlyelectrical activity; it tells us nothing about how well the heart is workingmechanically.

    Clinical Tip: Patients should be treated according to their symptoms,not merely their ECG.

    Clinical Tip: To obtain a 12-lead ECG, four wires are attached to eachlimb and six wires are attached at different locations on the chest. Thetotal of ten wires provides 12 views (12 leads).

    15

    BASICS

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  • BASICS

    16

    Limb Leads

    Electrodes are placed on the right arm (RA), left arm (LA), right leg (RL),and left leg (LL). With only four electrodes, six leads are viewed. Theseleads include the standard leadsI, II, and IIIand the augmentedleadsaVR, aVL, and aVF.

    Standard Limb Lead Electrode Placement

    LARA

    or

    RL LL

    RA LA

    LLRL

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  • Elements of Standard Limb Leads

    Lead Positive Electrode Negative Electrode View of HeartI LA RA LateralII LL RA InferiorIII LL LA Inferior

    Standard Limb Leads

    Leads I, II, and III make up the standard leads. If electrodes are placed on theright arm, left arm, and left leg, three leads are formed. If an imaginary lineis drawn between each of these electrodes, an axis is formed between eachpair of leads. The axes of these three leads form an equilateral triangle withthe heart in the center (Einthoven's triangle).

    17

    BASICS

    I

    IIIII

    LL

    RA LA

    Clinical Tip: Lead II is commonly called a monitoring lead. It providesinformation on heart rate, regularity, conduction time, and ectopic beats.The presence or location of an acute myocardial infarction (MI) should befurther diagnosed with a 12-lead ECG.

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  • Elements of Augmented Limb Leads

    Lead Positive Electrode View of Heart aVR RA NoneaVL LA LateralaVF LL Inferior

    BASICS

    18

    Augmented Limb Leads

    Leads aVR, aVL, and aVF make up the augmented leads. Each letter ofan augmented lead refers to a specific term: a = augmented; V = voltage;R = right arm; L = left arm; F = foot (the left foot).

    LL

    RA LA

    aVR aVL

    aVF

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  • Elements of Chest Leads

    Lead Positive Electrode Placement View of Heart

    V1 4th Intercostal space to right of sternum Septum

    V2 4th Intercostal space to left of sternum Septum

    V3 Directly between V2 and V4 Anterior

    V4 5th Intercostal space at left midclavicular line Anterior

    V5 Level with V4 at left anterior axillary line Lateral

    V6 Level with V5 at left midaxillary line Lateral

    Chest Leads

    Standard Chest Lead Electrode Placement

    The chest leads are identified as V1, V2, V3, V4, V5, and V6. Each electrodeplaced in a "V" position is positive.

    19

    BASICS

    Midclavicularline

    V1 V2V3 V4

    V5

    V6

    Anterioraxillary line

    Midaxillaryline

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  • Electrode Placement Using a 5-Wire Cable

    BASICS

    20

    Electrode Placement Using a 3-Wire Cable

    RA LA

    LL

    RA LA

    LLRL

    V1

    Clinical Tip: Five-wire telemetry units are commonly used to monitorleads I, II, II, aVR, aVL, aVF, and V1 in critical care settings.

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 20

  • Modified Chest Leads

    Modified chest leads (MCL) are useful in detecting bundle branchblocks and premature beats.

    Lead MCL1 simulates chest lead V1 and views the ventricular septum. Lead MCL6 simulates chest lead V6 and views the lateral wall of the

    left ventricle.

    21

    BASICS

    G

    Lead MCL1 electrode placement

    G

    Lead MCL6 electrode placement

    Clinical Tip: Write on the rhythm strip which simulated lead was used.

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 21

  • The Right-sided 12-Lead ECG

    Chest Leads PositionV1R 4th Intercostal space to left of sternumV2R 4th Intercostal space to right of sternumV3R Directly between V2R and V4RV4R 5th Intercostal space at right midclavicular lineV5R Level with V4R at right anterior axillary lineV6R Level with V5R at right midaxillary line

    The Right-sided 12-Lead ECG

    The limb leads are placed as usual but the chest leads are a mirrorimage of the standard 12-lead chest placement.

    The ECG machine cannot recognize that the leads have beenreversed. It will still print "V1V6" next to the tracing. Be sure to crossthis out and write the new lead positions on the ECG paper.

    BASICS

    22

    Midclavicularline

    Anterioraxillary line

    Midaxillaryline

    V6R

    V4R

    V5RV1RV2R

    V3R

    Clinical Tip: Patients with an acute inferior MI should have right-sidedECGs to assess for possible right ventricular infarction.

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  • The 15-Lead ECG

    Chest Leads Electrode Placement View of Heart

    V4R 5th Intercostal space in right anterior Right ventriclemidclavicular line

    V8 Posterior 5th intercostal space in left Posterior wall of midscapular line left ventricle

    V9 Directly between V8 and spinal column Posterior wall ofat posterior 5th intercostal space left ventricle

    The 15-Lead ECG

    Areas of the heart that are not well visualized by the six chest leads includethe wall of the right ventricle and the posterior wall of the left ventricle. A15-lead ECG, which includes the standard 12 leads plus leads V4R, V8, andV9, increases the chance of detecting an MI in these areas.

    23

    BASICS

    V9

    Spinalcolumn

    Leftshoulder

    V8

    V6

    V6 V8 V9V4R

    Clinical Tip: Use a 15-lead ECG when the 12-lead is normal but the his-tory is still suggestive of an acute infarction.

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 23

  • Recording of the ECG

    BASICS

    24

    1 mm 0.1 mv

    0.04 sec

    Constant speed of 25 mm/sec

    0.20 sec

    5 mm0.5 mv

    Smallbox

    Largebox

    Components of an ECG Tracing

    R

    Q S

    QT Interval

    P UT

    PR Interval

    STSegment

    QRSInterval

    Isoelectricline

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 24

  • Electrical Components

    Deflection DescriptionP Wave

    PR Interval

    QRS Complex

    ST Segment

    T Wave

    QT Interval

    U Wave

    25

    BASICS

    Electrical Activity

    Term DefinitionWave A deflection, either positive or negative, away from the

    baseline (isoelectric line) of the ECG tracing Complex Several wavesSegment A straight line between waves or complexesInterval A segment and a wave

    Clinical Tip: Between waves and cycles, the ECG records a baseline(isoelectric line), which indicates the absence of net electrical activity.

    First wave seenSmall rounded, upright (positive) wave indicating atrial

    depolarization (and contraction) Distance between beginning of P wave and beginning

    of QRS complexMeasures time during which a depolarization wave

    travels from the atria to the ventricles Three deflections following P waveIndicates ventricular depolarization (and contraction)Q Wave: First negative deflectionR Wave: First positive deflectionS Wave: First negative deflection after R waveDistance between S wave and beginning of T waveMeasures time between ventricular depolarization and

    beginning of repolarizationRounded upright (positive) wave following QRSRepresents ventricular repolarization Distance between beginning of QRS to end of T waveRepresents total ventricular activitySmall rounded, upright wave following T wave Most easily seen with a slow HRRepresents repolarization of Purkinje fibers

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 25

  • BASICS

    26

    Methods for Calculating Heart Rate

    Heart rate is the number of times the heart beats per minute (bpm). On anECG tracing, bpm is usually calculated as the number of QRS complexes.Included are extra beats, such as premature ventricular contractions (PVC),premature atrial contractions (PAC), and premature junctional contractions(PJC). The rate is measured from the R-R interval, the distance between oneR wave and the next. If the atrial rate (the number of P waves) and the ven-tricular rate (the number of QRS complexes) vary, the analysis may showthem as different rates, one atrial and one ventricular. The method chosen tocalculate HR varies according to rate and regularity on the ECG tracing.

    Method 1: Count Large Boxes

    Regular rhythms can be quickly determined by counting the number oflarge graph boxes between two R waves. That number is divided into 300to calculate bpm. The rates for the first one to six large boxes can be easilymemorized. Remember: 60 sec/min divided by 0.20 sec/large box = 300large boxes/min.

    506075100300 150

    Counting large boxes for heart rate. The rate is 60 bpm.

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 26

  • Methods 1 and 2 for Calculating Heart Rate

    Number of Large Number of Small Boxes Rate/Min Boxes Rate/Min

    1 300 2 7502 150 3 5003 100 4 3754 75 5 3005 60 6 2506 50 7 2147 43 8 1868 38 9 1679 33 10 150

    10 30 11 13611 27 12 12512 25 13 11513 23 14 10714 21 15 10015 20 16 94

    Method 2: Count Small Boxes

    The most accurate way to measure a regular rhythm is to count the numberof small boxes between two R waves. That number is divided into 1500 tocalculate bpm. Remember: 60 sec/min divided by 0.04 sec/small box =1500small boxes/min. Examples: If there are three small boxes between two R waves: 1500/3 =

    500 bpm.If there are five small boxes between two R waves: 1500/5 =300 bpm.

    27

    BASICS

    Clinical Tip: Approximate rate/min is rounded to the next-highestnumber.

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 27

  • BASICS

    28

    Meth

    od

    3: Six-S

    econ

    d E

    CG

    Rh

    ythm

    Strip

    Th

    e best m

    etho

    d fo

    r measu

    ring

    irregu

    lar heart rates w

    ith varyin

    g R

    -R in

    tervals is to co

    un

    t the n

    um

    ber

    of R

    waves in

    a 6-sec strip (in

    clud

    ing

    extra beats su

    ch as P

    VC

    s, PAC

    s, and

    PJC

    s) and

    mu

    ltiply b

    y 10. Th

    isg

    ives the averag

    e nu

    mb

    er of b

    eats per m

    inu

    te.

    Usin

    g a 6-sec E

    CG

    rhyth

    m strip

    to calcu

    late heart rate: 7 x 10 = 70 b

    pm

    .

    Clin

    ical Tip

    :If a rh

    ythm

    is extremely irreg

    ular, it is b

    est to co

    un

    t the n

    um

    ber o

    f R-R

    intervals p

    er 60 sec (1 m

    in).

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 28

  • The bpm is commonly the ventricular rateIf atrial and ventricular rates differ, as in a 3rd-degree

    block, measure both ratesNormal: 60100 bpmSlow (bradycardia): 100 bpmMeasure R-R intervals and P-P intervalsRegular: Intervals consistentRegularly irregular: Repeating patternIrregular: No patternIf present: Same in size, shape, position?Does each QRS have a P wave?Normal: Upright (positive) and uniform Inverted: Negative Notched: P' None: Rhythm is junctional or ventricularConstant: Intervals are the sameVariable: Intervals differNormal: 0.120.20 sec and constantNormal: 0.060.10 secWide: >0.10 secNone: Absent Beginning of QRS complex to end of T waveVaries with HRNormal: Less than half the RR interval Occur in AV blocksOccur in sinus arrestCompensatory: Complete pause following a premature

    atrial contraction (PAC), premature junctional contraction(PJC), or premature ventricular contraction (PVC)

    Noncompensatory: Incomplete pause following a PAC,PJC, or PVC

    ECG Interpretation

    29

    BASICS

    Analyzing a Rhythm

    Component CharacteristicRate

    Regularity

    P Waves

    PR Interval

    QRS Interval

    QT Interval

    Dropped beatsPause

    Continued

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 29

  • Classification of Arrhythmias

    Heart Rate ClassificationSlow BradyarrhythmiaFast TachyarrhythmiaAbsent Pulseless arrest

    Bigeminy: Repeating pattern of normal complex followedby a premature complex

    Trigeminy: Repeating pattern of 2 normal complexes followed by a premature complex

    Quadrigeminy: Repeating pattern of 3 normal complexesfollowed by a premature complex

    Couplet: 2 Consecutive premature complexesTriplet: 3 Consecutive premature complexes

    BASICS

    30

    Notes:

    Analyzing a Rhythmcontd

    Component CharacteristicQRS Complex grouping

    Normal Heart Rate (bpm)

    Age Awake Rate Mean Sleeping RateNewborn to 3 months 85205 140 801603 months to 2 years 100190 130 751602 to 10 years 60140 80 6090>10 years 60100 75 5090

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 30

  • 31

    BASICS

    Notes:

    2142_Tab01_001-031.qxd 9/12/09 2:13 PM Page 31

  • 32

    Sin

    oatrial (S

    A) N

    od

    e Arrh

    ythm

    ias

    U

    prig

    ht P

    waves all lo

    ok sim

    ilar. No

    te: All E

    CG

    strips in

    Tab 2 w

    ere record

    ed in

    Lead II.

    P

    R in

    tervals and

    QR

    S co

    mp

    lexes are of n

    orm

    al du

    ration

    .

    No

    rmal S

    inu

    s Rh

    ythm

    (NS

    R)

    Rate:N

    orm

    al (60100 bp

    m)

    Rh

    ythm

    :Reg

    ular

    P W

    aves:No

    rmal (u

    prig

    ht an

    d u

    nifo

    rm)

    PR

    Interval :N

    orm

    al (0.120.20 sec)Q

    RS

    :No

    rmal (0.060.10 sec)

    Clin

    ical Tip:A

    no

    rmal E

    CG

    do

    es no

    t exclud

    e heart d

    isease.

    Clin

    ical Tip:This rhythm

    is generated by the sinus node and its rate is within norm

    al limits (6080 bpm

    ).

    ECGS

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 32

  • Sin

    us B

    radycard

    ia

    T

    he S

    A n

    od

    e disch

    arges m

    ore slo

    wly th

    an in

    NS

    R.

    33

    ECGS

    Ra t e :S

    low

    (

  • 34

    Sin

    us Tach

    ycardia

    T

    he S

    A n

    od

    e disch

    arges m

    ore freq

    uen

    tly than

    in N

    SR

    .

    ECGS

    Ra t e :F a s t (>1 0 0 b

    pm

    )R

    hy t h

    m:R

    egu

    la rP

    Waves:N

    orm

    al (up

    righ

    t and

    un

    iform

    )P

    R In

    terval:No

    rmal (0.120.20 sec)

    QR

    S:N

    orm

    al (0.060.10 sec)

    Cl in

    ical T ip:S

    inu

    s tachycard

    ia may b

    e caused

    by exercise, an

    xiety, fever, hyp

    oxem

    ia, hyp

    ovo

    lemia,

    or card

    iac fai lure.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 34

  • Sin

    us A

    rrhyth

    mia

    T

    he S

    A n

    od

    e disch

    arges irreg

    ularly.

    T

    he R

    -R in

    terval is irregu

    lar. 35

    ECGS

    Ra t e :U

    sua lly n

    orm

    a l (6 0 1 0 0 bp

    m); fr e q

    uen

    tly inc r e a s e s w

    ith in

    s pir a tio

    n a n

    d d

    e c r e a s e s with

    e x pir a -

    tion

    ; may b

    e 0.12 sec P

    Waves:N

    orm

    al (up

    righ

    t and

    un

    iform

    )P

    R In

    terval :No

    rmal (0.120.20 sec)

    QR

    S:N

    orm

    al (0.060.10 sec)

    Clin

    ical T ip:

    Th

    e pacin

    g rate o

    f the S

    A n

    od

    e varies with

    respiratio

    n, esp

    ecially in ch

    ildren

    and

    eld-

    erly peo

    ple.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 35

  • 36

    Sin

    us P

    ause (S

    inu

    s Arrest)

    T

    he S

    A n

    od

    e fails to d

    ischarg

    e and

    then

    resum

    es.

    Electrical activity resu

    mes eith

    er wh

    en th

    e SA

    no

    de resets itself o

    r wh

    en a slo

    wer laten

    t pacem

    akerb

    egin

    s to d

    ischarg

    e.

    Th

    e pau

    se (arrest) time in

    terval is no

    t a mu

    ltiple o

    f the n

    orm

    al PP

    interval.

    ECGS

    3.96 - sec pause/arrest

    Rate:N

    orm

    al to slo

    w; d

    etermin

    ed b

    y du

    ration

    and

    frequ

    ency o

    f sinu

    s pau

    se (arrest)R

    hyth

    m:Irreg

    ular w

    hen

    ever a pau

    se (arrest) occu

    rsP

    Waves:N

    orm

    al (up

    righ

    t and

    un

    iform

    ) except in

    areas of p

    ause (arrest)

    PR

    Interval :N

    orm

    al (0.120.20 sec)Q

    RS

    :No

    rmal (0.060.10 sec)

    Cl in

    ical T ip:C

    ardiac o

    utp

    ut m

    ay decrease, cau

    sing

    synco

    pe o

    r dizzin

    ess.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 36

  • Sin

    oatrial (S

    A) B

    lock

    T

    he b

    lock o

    ccurs in

    som

    e mu

    ltiple o

    f the P

    P in

    terval.

    After th

    e dro

    pp

    ed b

    eat, cycles con

    tinu

    e on

    time.

    37

    ECGS

    Dropped beat

    X

    Ra t e :N

    orm

    a l to s lo

    w; d

    e te r min

    e d b

    y du

    r a tion

    a nd

    fr e qu

    enc y o

    f SA

    blo

    c kR

    hyth

    m:Irreg

    ular w

    hen

    ever an S

    A b

    lock o

    ccurs

    P W

    aves:No

    rmal (u

    prig

    ht an

    d u

    nifo

    rm) excep

    t in areas o

    f dro

    pp

    ed b

    eatsP

    R In

    terval:No

    rmal (0.120.20 sec)

    QR

    S:N

    orm

    al (0.060.10 sec)

    Cl in

    ical T ip:C

    ardiac o

    utp

    ut m

    ay decrease, cau

    sing

    synco

    pe o

    r dizzin

    ess.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 37

  • 38

    Atrial A

    rrhyth

    mias

    P

    waves d

    iffer in ap

    pearan

    ce from

    sinu

    s P w

    aves.

    QR

    S co

    mp

    lexes are of n

    orm

    al du

    ration

    if no

    ventricu

    lar con

    du

    ction

    distu

    rban

    ces are presen

    t.

    Wan

    derin

    g A

    trial Pacem

    aker (WA

    P)

    P

    acemaker site tran

    sfers from

    the S

    A n

    od

    e to o

    ther laten

    t pacem

    aker sites in th

    e atria and

    the A

    Vju

    nctio

    n an

    d th

    en m

    oves b

    ack to th

    e SA

    no

    de.

    ECGS

    Rate:N

    orm

    al (60100 bp

    m)

    Rh

    ythm

    :I rregu

    larP

    Waves:A

    t least three d

    ifferent fo

    rms, d

    etermin

    ed b

    y the fo

    cus in

    the atria

    PR

    Interval :Variab

    le; determ

    ined

    by fo

    cus

    QR

    S:N

    orm

    al (0.060.10 sec)

    Clin

    ical Tip:W

    AP

    may o

    ccur in

    no

    rmal h

    earts as a result o

    f fluctu

    ation

    s in vag

    al ton

    e.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 38

  • Mu

    ltifocal A

    trial Tachycard

    ia (MA

    T)

    T

    his fo

    rm o

    f WA

    P is asso

    ciated w

    ith a ven

    tricular resp

    on

    se >100 bp

    m.

    M

    AT

    may b

    e con

    fused

    with

    atrial fibrillatio

    n (A

    -fib); h

    ow

    ever, MA

    T h

    as a visible P

    wave.

    39

    ECGS

    Ra t e :F a s t (>1 0 0 b

    pm

    )R

    hyth

    m:Irreg

    ular

    P W

    ave:At least th

    ree differen

    t form

    s, determ

    ined

    by th

    e focu

    s in th

    e atriaP

    R In

    terval:Variable; d

    etermin

    ed b

    y focu

    sQ

    RS

    :No

    rmal (0.060.10 sec)

    Cl in

    ical T ip:M

    AT

    is com

    mo

    nly seen

    in p

    atients w

    ith ch

    ron

    ic ob

    structive p

    ulm

    on

    ary disease (C

    OP

    D)

    bu

    t may also

    occu

    r in an

    acute M

    I .

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 39

  • 40

    Prem

    ature A

    trial Co

    ntractio

    n (PA

    C)

    A

    sing

    le con

    traction

    occu

    rs earlier than

    the n

    ext expected

    sinu

    s con

    traction

    .

    After th

    e PAC

    , sinu

    s rhyth

    m u

    sually resu

    mes.

    ECGS

    PACPAC

    Ra t e :D

    epen

    ds o

    n r a te o

    f un

    de r ly in

    g r h

    y thm

    Rh

    ythm

    :Irregu

    lar wh

    enever a PA

    C o

    ccurs

    P W

    aves:Presen

    t; in th

    e PAC

    , may h

    ave a differen

    t shap

    eP

    R In

    terval:Varies in th

    e PAC

    ; oth

    erwise n

    orm

    al (0.120.20 sec)Q

    RS

    :No

    rmal (0.060.10 sec)

    Cl in

    ical T ip:In

    patien

    ts with

    heart d

    isease, frequ

    ent PA

    Cs m

    ay preced

    e paro

    xysmal su

    praven

    tricular

    tachycard

    ia (PS

    VT

    ), atrial fibri l latio

    n (A

    -fib), o

    r atrial flutter (A

    -flutter).

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 40

  • Atrial Tach

    ycardia

    A

    rapid

    atrial rate overrid

    es the S

    A n

    od

    e and

    beco

    mes th

    e do

    min

    ant p

    acemaker.

    S

    om

    e ST

    segm

    ent an

    d T

    wave ab

    no

    rmalities m

    ay be p

    resent.

    41

    ECGS

    Ra t e :1 5 0 2 5 0 b

    pm

    Rh

    ythm

    :Reg

    ular

    P W

    aves:No

    rmal (u

    prig

    ht an

    d u

    nifo

    rm) b

    ut d

    iffer in sh

    ape fro

    m sin

    us P

    waves

    PR

    Interval:M

    ay be sh

    ort (

  • 42

    Su

    praven

    tricular Tach

    ycardia (S

    VT

    )

    T

    his arrh

    ythm

    ia has su

    ch a fast rate th

    at the P

    waves m

    ay no

    t be seen

    .

    ECGS

    P wave

    buried in T w

    ave

    Ra t e :1 5 0 2 5 0 b

    pm

    Rh

    y t hm

    :Reg

    ula r

    P W

    aves:Frequ

    ently b

    uried

    in p

    recedin

    g T

    waves an

    d d

    ifficult to

    seeP

    R In

    terval:Usu

    ally no

    t po

    ssible to

    measu

    reQ

    RS

    :No

    rmal (0.060.10 sec) b

    ut m

    ay be w

    ide if ab

    no

    rmally co

    nd

    ucted

    thro

    ug

    h ven

    tricles

    Cl in

    ical T ip: S

    VT

    may b

    e related to

    caffeine in

    take, nico

    tine, stress, o

    r anxiety in

    health

    y adu

    lts.

    Cl in

    ical T ip:

    So

    me p

    atients m

    ay experien

    ce ang

    ina, h

    ypo

    tensio

    n, l ig

    ht-h

    eaded

    ness, p

    alpitatio

    ns,

    and

    inten

    se anxiety.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 42

  • Paro

    xysmal S

    up

    raventricu

    lar Tachycard

    ia (PS

    VT

    )

    P

    SV

    T is a rap

    id rh

    ythm

    that starts an

    d sto

    ps su

    dd

    enly.

    Fo

    r accurate in

    terpretatio

    n, th

    e beg

    inn

    ing

    or en

    d o

    f the P

    SV

    T m

    ust b

    e seen.

    P

    SV

    T is so

    metim

    es called p

    aroxysm

    al atrial tachycard

    ia (PAT

    ).

    43

    ECGS

    Sudden onset of SVT

    Rate:150250 b

    pm

    Rh

    ythm

    :Irregu

    larP

    Waves:Freq

    uen

    tly bu

    ried in

    preced

    ing

    T w

    aves and

    difficu

    lt to see

    PR

    Interval:U

    sually n

    ot p

    ossib

    le to m

    easure

    QR

    S:N

    orm

    al (0.060.10 sec) bu

    t may b

    e wid

    e if abn

    orm

    al ly con

    du

    cted th

    rou

    gh

    ventricles

    Cl in

    ical T ip:T

    he p

    atient m

    ay feel palp

    itation

    s, dizzin

    ess, l igh

    thead

    edn

    ess, or an

    xiety.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 43

  • 44

    Atrial Flu

    tter (A-flu

    tter)

    A

    V n

    od

    e con

    du

    cts imp

    ulses to

    the ven

    tricles at a ratio o

    f 2:1, 3:1, 4:1, or g

    reater (rarely 1:1).

    Th

    e deg

    ree of A

    V b

    lock m

    ay be co

    nsisten

    t or variab

    le.

    ECGS

    Flutter wave

    s

    Ra t e :A

    tr ia l: 2 5 0 3 5 0 bp

    m; v e n

    tr ic ula r : v a r ia b

    leR

    hyth

    m:A

    trial: regu

    lar; ventricu

    lar: variable

    P W

    aves:Flutter w

    aves have a saw

    -too

    thed

    app

    earance; so

    me m

    ay be b

    uried

    in th

    e QR

    S an

    d n

    ot visib

    leP

    R In

    terval:Variable

    QR

    S:U

    sual ly n

    orm

    al (0.060.10 sec), bu

    t may ap

    pear w

    iden

    ed if flu

    tter waves are b

    uried

    in Q

    RS

    Cl in

    ical T ip:A

    -flutter m

    ay be th

    e first ind

    ication

    of card

    iac disease.

    Cl in

    ical T ip:S

    ign

    s and

    symp

    tom

    s dep

    end

    on

    ventricu

    lar respo

    nse rate.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 44

  • Atrial Fib

    rillation

    (A-fib

    )

    R

    apid

    , erratic electrical disch

    arge co

    mes fro

    m m

    ultip

    le atrial ectop

    ic foci.

    N

    o o

    rgan

    ized atrial d

    epo

    larization

    is detectab

    le.45

    ECGS

    Irregular R-R intervals

    Ra t e :A

    tr ia l: 3 5 0 bp

    m; v e n

    tr ic ula r : v a r ia b

    leR

    hyth

    m:Irreg

    ular

    P W

    aves:No

    true P

    waves; ch

    aotic atrial activity

    PR

    Interval:N

    on

    eQ

    RS

    :No

    rmal (0.060.10 sec)

    Cl in

    ical T ip:A

    -fib is u

    sual ly a ch

    ron

    ic arrhyth

    mia asso

    ciated w

    ith u

    nd

    erlying

    heart d

    isease.

    Cl in

    ical T ip:S

    ign

    s and

    symp

    tom

    s dep

    end

    on

    ventricu

    lar respo

    nse rate.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 45

  • 46

    Wo

    lff-Parkin

    son

    -Wh

    ite (WP

    W) S

    ynd

    rom

    e

    In

    WP

    W, an

    accessory co

    nd

    uctio

    n p

    athw

    ay is presen

    t betw

    een th

    e atria and

    the ven

    tricles.E

    lectrical imp

    ulses are rap

    idly co

    nd

    ucted

    to th

    e ventricles.

    T

    hese rap

    id im

    pu

    lses slur th

    e initial p

    ortio

    n o

    f the Q

    RS

    ; the slu

    rred effect is called

    a delta w

    ave.

    ECGS

    Delta

    wa ve

    Rate:D

    epen

    ds o

    n rate o

    f un

    derlyin

    g rh

    ythm

    Rh

    ythm

    :Reg

    ular u

    nless asso

    ciated w

    ith A

    -fibP

    Waves:N

    orm

    al (up

    righ

    t and

    un

    iform

    ) un

    less A-fib

    is presen

    tP

    R In

    terval :Sh

    ort (0.10 sec); d

    elta wave p

    resent

    Cl in

    ical T ip:W

    PW

    is associated

    with

    narro

    w-co

    mp

    lex tachycard

    ias, inclu

    din

    g A

    -flutter an

    d A

    -fib.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 46

  • Jun

    ction

    al Arrh

    ythm

    ias

    T

    he atria an

    d S

    A n

    od

    e do

    no

    t perfo

    rm th

    eir no

    rmal p

    acemakin

    g fu

    nctio

    ns.

    A

    jun

    ction

    al escape rh

    ythm

    beg

    ins.

    Jun

    ction

    al Rh

    ythm

    47

    ECGS

    Inve

    rted P wave

    Absent P wave

    Rate:4060 b

    pm

    Rh

    ythm

    :Reg

    ular

    P W

    aves:Ab

    sent, in

    verted, b

    uried

    , or retro

    grad

    eP

    R In

    terval :No

    ne, sh

    ort, o

    r retrog

    rade

    QR

    S:N

    orm

    al (0.060.10 sec)

    Clin

    ical T ip:

    Sin

    us n

    od

    e disease th

    at causes in

    app

    rop

    riate slow

    ing

    of th

    e sinu

    s no

    de m

    ay exacer-b

    ate this rh

    ythm

    . You

    ng

    , health

    y adu

    lts, especially th

    ose w

    ith in

    creased vag

    al ton

    e du

    ring

    sleep, o

    ftenh

    ave perio

    ds o

    f jun

    ction

    al rhyth

    m th

    at is com

    pletely b

    enig

    n, n

    ot req

    uirin

    g in

    terventio

    n.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 47

  • 48

    Accelerated

    Jun

    ction

    al Rh

    ythm

    ECGS

    Absent P wave

    Ra t e :6 1 1 0 0 b

    pm

    Rh

    y t hm

    :Reg

    ula r

    P W

    a v e s :Ab

    s e nt, in

    v e r te d, b

    ur ie d

    , or r e tr o

    gr a d

    eP

    R In

    terval:No

    ne, sh

    ort, o

    r retrog

    rade

    QR

    S:N

    orm

    al (0.060.10 sec)

    Clin

    ical Tip:M

    on

    itor th

    e patien

    t, no

    t just th

    e EC

    G, fo

    r clinical im

    pro

    vemen

    t.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 48

  • Jun

    ction

    al Tachycard

    ia

    49

    ECGS

    Retrog

    rade P wave

    Ra t e :1 0 1 1 8 0 b

    pm

    Rh

    y t hm

    :Reg

    ula r

    P W

    a v e s :Ab

    s e nt, in

    v e r te d, b

    ur ie d

    , or r e tr o

    gr a d

    eP

    R In

    terval:No

    ne, sh

    ort, o

    r retrog

    rade

    QR

    S:N

    orm

    al (0.060.10 sec)

    Clin

    ical Tip

    :S

    ign

    s an

    d

    symp

    tom

    s o

    f d

    ecreased

    cardiac

    ou

    tpu

    t m

    ay b

    e seen

    in

    resp

    on

    se to

    the rap

    id rate.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 49

  • 50

    Jun

    ction

    al Escap

    e Beat

    A

    n escap

    e com

    plex co

    mes later th

    an th

    e next exp

    ected sin

    us co

    mp

    lex.

    ECGS

    Jun

    ctional escape beats

    Ra t e :D

    epen

    ds o

    n r a te o

    f un

    de r ly in

    g r h

    y thm

    Rh

    y t hm

    :Ir r e gu

    la r wh

    ene v e r a n

    e s c a pe b

    e a t oc c u

    r sP

    Waves:N

    on

    e, inverted

    , bu

    ried, o

    r retrog

    rade in

    the escap

    e beat

    PR

    Interval:N

    on

    e, sho

    rt, or retro

    grad

    eQ

    RS

    :No

    rmal (0.060.10 sec)

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 50

  • Prem

    ature Ju

    nctio

    nal C

    on

    traction

    (PJC

    )

    E

    nh

    anced

    auto

    maticity in

    the A

    V ju

    nctio

    n p

    rod

    uces P

    JCs.

    51

    ECGS

    PJCPJC

    Ra t e :D

    epen

    ds o

    n r a te o

    f un

    de r ly in

    g r h

    y thm

    Rh

    y t hm

    :Ir r e gu

    la r wh

    ene v e r a P

    J C o

    c c ur s

    P W

    aves:Ab

    sent, in

    verted, b

    uried

    , or retro

    grad

    e in th

    e PJC

    PR

    Interval:N

    on

    e, sho

    rt, or retro

    grad

    eQ

    RS

    :No

    rmal (0.060.10 sec)

    Cl in

    ical T ip:B

    efore d

    ecidin

    g w

    heth

    er isolated

    PJC

    s are insig

    nifican

    t, con

    sider th

    e cause.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 51

  • 52

    Ven

    tricular A

    rrhyth

    mias

    In

    all ventricu

    lar rhyth

    ms, th

    e QR

    S co

    mp

    lex is >0.10 sec. P W

    aves are absen

    t or, if visib

    le, have n

    oco

    nsisten

    t relation

    ship

    to th

    e QR

    S co

    mp

    lex.

    Idio

    ventricu

    lar Rh

    ythm

    ECGS

    Rate:2040 b

    pm

    Rh

    ythm

    :Reg

    ular

    P W

    aves:No

    ne

    PR

    Interval :N

    on

    eQ

    RS

    :Wid

    e (>0.10 sec), bizarre ap

    pearan

    ce

    Clin

    ical T ip:D

    imin

    ished

    cardiac o

    utp

    ut is exp

    ected b

    ecause o

    f the slo

    w h

    eart rate. An

    idio

    ventricu

    -lar rh

    ythm

    may b

    e called an

    ago

    nal rh

    ythm

    wh

    en th

    e heart rate d

    rop

    s belo

    w 20 b

    pm

    . An

    ago

    nal rh

    ythm

    is gen

    erally termin

    al and

    is usu

    ally the last rh

    ythm

    befo

    re asystole.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 52

  • Accelerated

    Idio

    ventricu

    lar Rh

    ythm

    53

    ECGS

    Ra t e :4 1 1 0 0 b

    pm

    Rh

    y t hm

    :Reg

    ula r

    P W

    a v e s :No

    ne

    PR

    Interval:N

    on

    eQ

    RS

    :Wid

    e (>0.10 sec), bizarre ap

    pearan

    ce

    Clin

    ical Tip:

    Idio

    ventricu

    lar rhyth

    ms ap

    pear w

    hen

    sup

    raventricu

    lar pacin

    g sites are d

    epressed

    or

    absen

    t. Dim

    inish

    ed card

    iac ou

    tpu

    t is expected

    if the h

    eart rate is slow

    .

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 53

  • 54

    Prem

    ature V

    entricu

    lar Co

    ntractio

    n (P

    VC

    )

    P

    VC

    s result fro

    m an

    irritable ven

    tricular fo

    cus.

    P

    VC

    s may b

    e un

    iform

    (same fo

    rm) o

    r mu

    ltiform

    (differen

    t form

    s).

    Usu

    ally a PV

    C is fo

    llow

    ed b

    y a full co

    mp

    ensato

    ry pau

    se becau

    se the sin

    us n

    od

    e timin

    g is n

    ot in

    ter-ru

    pted

    . In co

    ntrast, a P

    VC

    may b

    e follo

    wed

    by a n

    on

    com

    pen

    satory p

    ause if th

    e PV

    C en

    ters the sin

    us

    no

    de an

    d resets its tim

    ing

    , enab

    ling

    the fo

    llow

    ing

    sinu

    s P w

    ave to ap

    pear earlier th

    an exp

    ected.

    ECGS

    PVC

    Rate:D

    epen

    ds o

    n rate o

    f un

    derlyin

    g rh

    ythm

    Rh

    ythm

    :Irregu

    lar wh

    enever a P

    VC

    occu

    rsP

    Waves:N

    on

    e associated

    with

    the P

    VC

    PR

    Interval :N

    on

    e associated

    with

    the P

    VC

    QR

    S:W

    ide (>0.10 sec), b

    izarre app

    earance

    Clin

    ical Tip:

    Patien

    ts may sen

    se PV

    Cs as skip

    ped

    beats. B

    ecause th

    e ventricles are o

    nly p

    artiallyfilled

    , the P

    VC

    frequ

    ently d

    oes n

    ot g

    enerate a p

    ulse.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 54

  • Prem

    ature V

    entricu

    lar Co

    ntractio

    n: U

    nifo

    rm (sam

    e form

    )

    55

    ECGS

    Prem

    ature V

    ent r icu

    lar Co

    nt r act io

    n: M

    ult if o

    rm (d

    if f er ent f o

    rms )

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 55

  • 56

    Prem

    ature V

    entricu

    lar Co

    ntractio

    n: V

    entricu

    lar Big

    emin

    y (PV

    C every 2

    nd

    beat)

    ECGS

    Prem

    ature V

    ent r icu

    lar Co

    nt r act io

    n: V

    ent r icu

    lar Tr igem

    iny (P

    VC

    every 3rd

    beat )

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 56

  • Prem

    ature V

    entricu

    lar Co

    ntractio

    n: V

    entricu

    lar Qu

    adrig

    emin

    y (PV

    C every

    4th

    beat)

    57

    ECGS

    Co u p le ts

    Prem

    ature V

    ent r icu

    lar Co

    nt r act io

    n: C

    ou

    plet s (p

    air ed P

    VC

    s )

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 57

  • 58

    Prem

    ature V

    entricu

    lar Co

    ntractio

    n: R

    -on

    -T P

    hen

    om

    eno

    n

    T

    he P

    VC

    s occu

    r so early th

    at they fall o

    n th

    e T w

    ave of th

    e preced

    ing

    beat.

    T

    hese P

    VC

    s occu

    r du

    ring

    the refracto

    ry perio

    d o

    f the ven

    tricles, a vuln

    erable p

    eriod

    becau

    se the

    cardiac cells h

    ave no

    t fully rep

    olarized

    .

    ECGS

    Rate:D

    epen

    ds o

    n rate o

    f un

    derlyin

    g rh

    ythm

    Rh

    ythm

    :Irregu

    lar wh

    enever a P

    VC

    occu

    rsP

    Waves:N

    on

    e associated

    with

    the P

    VC

    PR

    Interval :N

    on

    e associated

    with

    the P

    VC

    QR

    S:W

    ide (>0.10 sec), b

    izarre app

    earance

    Cl in

    ical T ip:In

    acute isch

    emia, R

    -on

    -T p

    hen

    om

    eno

    n m

    ay be esp

    ecial ly dan

    gero

    us b

    ecause th

    e ven-

    tricles may b

    e mo

    re vuln

    erable to

    ventricu

    lar tachycard

    ia (VT

    ) or ven

    tricular fib

    rillation

    (VF).

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 58

  • Prem

    ature C

    on

    traction

    : Interp

    olated

    PV

    C

    T

    he P

    VC

    occu

    rs betw

    een tw

    o reg

    ular co

    mp

    lexes; it may ap

    pear san

    dw

    iched

    betw

    een tw

    o n

    orm

    alb

    eats.

    An

    interp

    olated

    PV

    C d

    oes n

    ot in

    terfere with

    the n

    orm

    al cardiac cycle.

    59

    ECGS

    Interpolated PVC

    Rate:D

    epen

    ds o

    n rate o

    f un

    derlyin

    g rh

    ythm

    Rh

    ythm

    :Irregu

    lar wh

    enever a P

    VC

    occu

    rsP

    Waves:N

    on

    e associated

    with

    the P

    VC

    PR

    Interval :N

    on

    e associated

    with

    the P

    VC

    QR

    S:W

    ide (>0.10 sec), b

    izarre app

    earance

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 59

  • 60

    Ven

    tricular Tach

    ycardia (V

    T): M

    on

    om

    orp

    hic

    In

    mo

    no

    mo

    rph

    ic VT, Q

    RS

    com

    plexes h

    ave the sam

    e shap

    e and

    amp

    litud

    e.

    ECGS

    Ra t e :1 0 0 2 5 0 b

    pm

    Rh

    y t hm

    :Reg

    ula r

    P W

    aves:No

    ne o

    r no

    t associated

    with

    the Q

    RS

    PR

    Interval:N

    on

    eQ

    RS

    :Wid

    e (>0.10 sec), bizarre ap

    pearan

    ce

    Cl in

    ical T ip:I t is im

    po

    rtant to

    con

    firm th

    e presen

    ce or ab

    sence o

    f pu

    lses becau

    se mo

    no

    mo

    rph

    ic VT

    may b

    e perfu

    sing

    or n

    on

    perfu

    sing

    .

    Cl in

    ical T ip:M

    on

    om

    orp

    hic V

    T w

    i l l pro

    bab

    ly deterio

    rate into

    VF o

    r un

    stable V

    T if su

    stained

    and

    no

    ttreated

    .

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 60

  • Ven

    tricular Tach

    ycardia (V

    T): P

    olym

    orp

    hic

    In

    po

    lymo

    rph

    ic VT, Q

    RS

    com

    plexes vary in

    shap

    e and

    amp

    litud

    e.

    Th

    e QT

    interval is n

    orm

    al or lo

    ng

    . 61

    ECGS

    Ra t e :1 0 0 2 5 0 b

    pm

    Rh

    ythm

    :Reg

    ular o

    r irregu

    larP

    Waves:N

    on

    e or n

    ot asso

    ciated w

    ith th

    e QR

    SP

    R In

    terval:No

    ne

    QR

    S:W

    ide (>0.10 sec), b

    izarre app

    earance

    Cl in

    ical T ip:I t is im

    po

    rtant to

    determ

    ine w

    heth

    er pu

    lses are presen

    t becau

    se po

    lymo

    rph

    ic VT

    may

    be p

    erfusin

    g o

    r no

    np

    erfusin

    g.

    Clin

    ical Tip:C

    on

    sider electro

    lyte abn

    orm

    alities as a po

    ssible cau

    se.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 61

  • 62

    Torsad

    e de P

    oin

    tes

    T

    he Q

    RS

    reverses po

    larity and

    the strip

    sho

    ws a sp

    ind

    le effect.

    Th

    is rhyth

    m is an

    un

    usu

    al variant o

    f po

    lymo

    rph

    ic VT

    with

    lon

    g Q

    T in

    tervals.

    In Fren

    ch th

    e term m

    eans tw

    isting

    of p

    oin

    ts.

    ECGS

    Rate:200250 b

    pm

    Rh

    ythm

    :Irregu

    larP

    Waves:N

    on

    eP

    R In

    terval :No

    ne

    QR

    S:W

    ide (>0.10 sec), b

    izarre app

    earance

    Cl in

    ical T ip:To

    rsade d

    e po

    intes m

    ay deterio

    rate to V

    F or asysto

    le.

    Clin

    ical T ip:

    Frequ

    ent cau

    ses are dru

    gs th

    at pro

    lon

    g th

    e QT

    interval, an

    d electro

    lyte abn

    orm

    alitiessu

    ch as h

    ypo

    mag

    nesem

    ia.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 62

  • Ven

    tricular Fib

    rillation

    (VF)

    C

    hao

    tic electrical activity occu

    rs with

    no

    ventricu

    lar dep

    olarizatio

    n o

    r con

    traction

    .

    Th

    e amp

    litud

    e and

    frequ

    ency o

    f the fib

    rillatory activity can

    defin

    e the typ

    e of fib

    rillation

    as coarse,

    med

    ium

    , or fin

    e. Sm

    all baselin

    e un

    du

    lation

    s are con

    sidered

    fine; larg

    e on

    es are coarse.

    63

    ECGS

    Rate:In

    determ

    inate

    Rh

    ythm

    :Ch

    aotic

    P W

    aves:No

    ne

    PR

    Interval :N

    on

    eQ

    RS

    :No

    ne

    Cl in

    ical T ip:T

    here is n

    o p

    ulse o

    r cardiac o

    utp

    ut. R

    apid

    interven

    tion

    is critical . Th

    e lon

    ger th

    e delay,

    the less th

    e chan

    ce of co

    nversio

    n.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 63

  • 64

    Pu

    lseless Electrical A

    ctivity (PE

    A)

    T

    he m

    on

    itor sh

    ow

    s an id

    entifiab

    le electrical rhyth

    m, b

    ut n

    o p

    ulse is d

    etected.

    T

    he rh

    ythm

    may b

    e sinu

    s, atrial, jun

    ction

    al, or ven

    tricular.

    P

    EA

    is also called

    electrom

    echan

    ical disso

    ciation

    (EM

    D).

    ECGS

    Rate:R

    eflects un

    derlyin

    g rh

    ythm

    Rh

    ythm

    :Reflects u

    nd

    erlying

    rhyth

    mP

    Waves:R

    eflects un

    derlyin

    g rh

    ythm

    PR

    Interval :R

    eflects un

    derlyin

    g rh

    ythm

    QR

    S:R

    eflects un

    derlyin

    g rh

    ythm

    Cl in

    ical T ip:P

    oten

    tial causes o

    f PE

    A are trau

    ma, ten

    sion

    pn

    eum

    oth

    orax, th

    rom

    bo

    sis (pu

    lmo

    nary o

    rco

    ron

    ary), cardiac tam

    po

    nad

    e, toxin

    s, hyp

    o- o

    r hyp

    erkalemia, h

    ypo

    volem

    ia, hyp

    oxia, h

    ypo

    glycem

    ia,h

    ypo

    therm

    ia, and

    hyd

    rog

    en io

    n (acid

    osis).

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 64

  • Asysto

    le

    E

    lectrical activity in th

    e ventricles is co

    mp

    letely absen

    t.65

    ECGS

    Ra t e :N

    on

    eR

    hy t h

    m:N

    on

    eP

    Waves:N

    on

    eP

    R In

    terval:No

    ne

    QR

    S:N

    on

    e

    Cl in

    ical T ip:R

    ule o

    ut o

    ther cau

    ses such

    as loo

    se leads, n

    o p

    ow

    er, or in

    sufficien

    t sign

    al gain

    .

    Cl in

    ical T ip:S

    eek to id

    entify th

    e un

    derlyin

    g cau

    se as in P

    EA

    . Also

    , search to

    iden

    tify VF.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 65

  • 66

    Atrio

    ventricu

    lar (AV

    ) Blo

    cks

    A

    V b

    locks are d

    ivided

    into

    three categ

    ories: first, seco

    nd

    , and

    third

    deg

    ree.

    First-Deg

    ree AV

    Blo

    ck

    ECGS

    Rate:D

    epen

    ds o

    n rate o

    f un

    derlyin

    g rh

    ythm

    Rh

    ythm

    :Reg

    ular

    P W

    aves:No

    rmal (u

    prig

    ht an

    d u

    nifo

    rm)

    PR

    Interval :P

    rolo

    ng

    ed (>0.20 sec)

    QR

    S:N

    orm

    al (0.060.10 sec)

    Cl in

    ical T ip:U

    sual ly a first-d

    egree A

    V b

    lock is b

    enig

    n, b

    ut i f asso

    ciated w

    ith an

    acute M

    I i t may lead

    to fu

    rther A

    V d

    efects.

    Clin

    ical Tip:

    Often

    AV

    blo

    ck is caused

    by m

    edicatio

    ns th

    at pro

    lon

    g A

    V co

    nd

    uctio

    n; th

    ese inclu

    de

    dig

    oxin

    , calcium

    chan

    nel b

    lockers, an

    d b

    eta blo

    ckers.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 66

  • Seco

    nd

    -Deg

    ree AV

    Blo

    ckTyp

    e I(M

    ob

    itz I or W

    enckeb

    ach)

    P

    R in

    tervals beco

    me p

    rog

    ressively lon

    ger u

    ntil o

    ne P

    wave is to

    tally blo

    cked an

    d p

    rod

    uces n

    o Q

    RS

    com

    plex. A

    fter a pau

    se, du

    ring

    wh

    ich th

    e AV

    no

    de reco

    vers, this cycle is rep

    eated.

    67

    ECGS

    Blocked beatX

    Rate:D

    epen

    ds o

    n rate o

    f un

    derlyin

    g rh

    ythm

    Rh

    ythm

    : Atrial: reg

    ular; ven

    tricular: irreg

    ular

    P W

    aves:No

    rmal (u

    prig

    ht an

    d u

    nifo

    rm), m

    ore P

    waves th

    an Q

    RS

    com

    plexes

    PR

    Interval :P

    rog

    ressively lon

    ger u

    nti l o

    ne P

    wave is b

    locked

    and

    a QR

    S is d

    rop

    ped

    QR

    S:N

    orm

    al (0.060.10 sec)

    Cl in

    ical T ip:T

    his rh

    ythm

    may b

    e caused

    by m

    edicatio

    n su

    ch as b

    eta blo

    ckers, dig

    oxin

    , and

    calcium

    chan

    nel b

    lockers. Isch

    emia in

    volvin

    g th

    e righ

    t coro

    nary artery is an

    oth

    er cause.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 67

  • 68

    Seco

    nd

    -Deg

    ree AV

    Blo

    ckTyp

    e II (M

    ob

    itz II)

    C

    on

    du

    ction

    ratio (P

    waves to

    QR

    S co

    mp

    lexes) is com

    mo

    nly 2:1, 3:1, o

    r 4:1, or variab

    le.

    QR

    S co

    mp

    lexes are usu

    ally wid

    e becau

    se this b

    lock u

    sually in

    volves b

    oth

    bu

    nd

    le bran

    ches.

    ECGS

    Rate:A

    trial: usu

    ally 60100 bp

    m; ven

    tricular: slo

    wer th

    an atrial rate

    Rh

    ythm

    :Atrial: reg

    ular; ven

    tricular: reg

    ular o

    r irregu

    larP

    Waves:N

    orm

    al (up

    righ

    t and

    un

    iform

    ); mo

    re P w

    aves than

    QR

    S co

    mp

    lexesP

    R In

    terval :No

    rmal o

    r pro

    lon

    ged

    bu

    t con

    stant

    QR

    S:M

    ay be n

    orm

    al , bu

    t usu

    al ly wid

    e (>0.10 sec) if the b

    un

    dle b

    ranch

    es are invo

    lved

    Cl in

    ical T ip:

    Resu

    lting

    brad

    ycardia can

    com

    pro

    mise card

    iac ou

    tpu

    t and

    lead to

    com

    plete A

    V b

    lock.

    Th

    is rhyth

    m o

    ften o

    ccurs w

    ith card

    iac ischem

    ia or an

    MI.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 68

  • 69

    ECGS

    Th

    ird-D

    egree A

    V B

    lock

    C

    on

    du

    ction

    betw

    een atria an

    d ven

    tricles is totally ab

    sent b

    ecause o

    f com

    plete electrical b

    lock at o

    rb

    elow

    the A

    V n

    od

    e. Th

    is is kno

    wn

    as AV

    disso

    ciation

    .

    Co

    mp

    lete heart b

    lock is an

    oth

    er nam

    e for th

    is rhyth

    m.

    Rate:A

    trial: 60100 bp

    m; ven

    tricular: 4060 b

    pm

    if escape fo

    cus is ju

    nctio

    nal,

  • 70

    Bu

    nd

    le Bran

    ch B

    lock (B

    BB

    )

    E

    ither th

    e left or th

    e righ

    t ventricle m

    ay dep

    olarize late, creatin

    g a w

    ide o

    r no

    tched

    QR

    S

    com

    plex.

    ECGS

    Notched QRS

    Ra t e :D

    epen

    ds o

    n r a te o

    f un

    de r ly in

    g r h

    y thm

    Rh

    ythm

    :Reg

    ular

    P W

    aves:No

    rmal (u

    prig

    ht an

    d u

    nifo

    rm)

    PR

    Interval:N

    orm

    al (0.120.20 sec)Q

    RS

    :Wid

    e (>0.10 sec) with

    a no

    tched

    app

    earance

    Cl in

    ical T ip:B

    un

    dle b

    ranch

    blo

    ck com

    mo

    nly o

    ccurs in

    coro

    nary artery d

    isease.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 70

  • Artificial C

    ardiac P

    acemak

    ers

    Artificial p

    acemakers electro

    nically stim

    ulate th

    e heart in

    place o

    f the h

    earts ow

    n p

    acemaker.

    P

    acemakers m

    ay be p

    reset to stim

    ulate th

    e hearts activity co

    ntin

    uo

    usly o

    r interm

    ittently.

    Temp

    orary P

    acemaker

    P

    aces the h

    eart thro

    ug

    h ep

    icardial, tran

    sveno

    us, o

    r transcu

    taneo

    us ro

    utes. T

    he p

    ulse g

    enerato

    r islo

    cated extern

    ally.

    Perm

    anen

    t Pacem

    aker

    Its circu

    itry sealed in

    an airtig

    ht case, th

    e pacem

    aker is imp

    lanted

    in th

    e bo

    dy. It u

    ses sensin

    g an

    dp

    acing

    device lead

    s.

    Sin

    gle-C

    ham

    ber P

    acemaker

    O

    ne le a d

    is pla c e d

    in th

    e he a r t a n

    d p

    a c e s a s ing

    le he a r t c h

    a mb

    e r (e ithe r a tr iu

    m o

    r v e ntr ic le ).

    Du

    a l-Ch

    amb

    e r Pa c e m

    a k e r

    O

    ne lead is placed in the right atrium and the other in the right ventricle. The atrial electrode generates a spike that

    should be followed by a P w

    ave, and the ventricular electrode generates a spike followed by a w

    ide QR

    S com

    plex.

    Pacem

    aker Mo

    des

    Fixed

    rate (asynch

    ron

    ou

    s): Disch

    arges at a p

    reset rate (usu

    al ly 7080 bp

    m) reg

    ardless o

    f the

    patien

    ts ow

    n electrical activity.

    D

    eman

    d (syn

    chro

    no

    us): D

    ischarg

    es on

    ly wh

    en th

    e patien

    ts heart rate d

    rop

    s belo

    w th

    e pacem

    akersp

    reset (base) rate.

    Clin

    ical Tip:P

    atients w

    ith p

    acemakers m

    ay receive defib

    rillation

    , bu

    t avoid

    placin

    g th

    e defib

    rillator

    pad

    dles o

    r pad

    s closer th

    an 5 in

    ches to

    the p

    acemaker b

    attery pack.

    71

    ECGS

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 71

  • 72

    Artificial C

    ardiac P

    acemak

    ersECGS

    Pacem

    aker C

    od

    esC

    ham

    ber

    Ch

    amb

    er R

    espo

    nse to

    Pro

    gram

    mab

    le R

    espo

    nse to

    P

    acedS

    ensed

    Sen

    sing

    Fun

    ction

    sTach

    ycardia

    A =

    Atriu

    mV

    =

    Ventricle

    D =

    Du

    al (atrium

    an

    d ven

    tricle)O

    =

    No

    ne

    Ar t if icial P

    acemak

    er Rh

    ythm

    Ra t e

    Va r ie s a c c or d

    ing

    to p

    r e s e t pa c e m

    a k e r r a te . R

    hy t h

    mR

    egu

    la r for a s y n

    c hr o

    no

    us p

    a c e ma k e r ; ir r e g

    ula r fo

    r de m

    a nd

    pa c e m

    a k e r un

    le s s 1 0 0 %p

    a c e d w

    ith n

    o in

    tr ins ic b

    e a ts .P

    waves

    No

    ne p

    rod

    uced

    by ven

    tricular p

    acemaker. S

    inu

    s P w

    aves may b

    e seen b

    ut are u

    nrelated

    toQ

    RS

    . Atrial o

    r du

    al-cham

    ber p

    acemaker sh

    ou

    ld h

    ave P w

    aves follo

    win

    g each

    atrial spike.

    PR

    Interval

    None for ventricular pacer. A

    trial or dual-chamber pacem

    aker produces constant PR intervals.

    QR

    SW

    ide (>0.10 sec) fo

    l low

    ing

    each ven

    tricular sp

    ike in a p

    acemaker rh

    ythm

    . Th

    e patien

    tso

    wn

    electrical activity may g

    enerate a Q

    RS

    com

    plex th

    at loo

    ks differen

    t from

    the p

    acedQ

    RS

    s. I f atrial ly paced

    on

    ly, the Q

    RS

    may b

    e with

    in n

    orm

    al l imits.

    A =

    Atriu

    mV

    =

    Ventricle

    D =

    Du

    al (atrium

    and

    ventricle)

    O =

    No

    ne

    T =

    Trigg

    ers pacin

    gI

    =In

    hib

    its pacin

    gD

    =

    Du

    al (trigg

    ersan

    d in

    hib

    its)O

    =

    No

    ne

    P =

    Basic p

    rog

    rams

    (rate and

    ou

    tpu

    t)M

    =

    Mu

    ltiple p

    rog

    rams

    C =

    Co

    mm

    un

    ication

    (i.e., telemetry)

    R =

    Rate resp

    on

    seO

    =

    No

    ne

    P =

    Pacin

    gS

    =

    Sh

    ock

    D =

    Du

    al (pace

    and

    sho

    ck)O

    =

    No

    ne

    Clin

    ical T ip:O

    nce an

    imp

    ulse is g

    enerated

    by th

    e pacem

    aker, it app

    ears as a spike, eith

    er abo

    ve or

    belo

    w th

    e baselin

    e (isoelectric lin

    e), on

    the E

    CG

    . Th

    e spike in

    dicates th

    at the p

    acemaker h

    as fired.

    Clin

    ical Tip:A

    pacem

    aker is in cap

    ture w

    hen

    a spike p

    rod

    uces an

    EC

    G w

    ave or co

    mp

    lex.

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 72

  • Sin

    gle-C

    ham

    ber P

    acemaker R

    hyth

    mA

    trial

    73

    ECGS

    Pace

    make

    r spike

    Pa

    cem

    aker spike

    Sin

    gle -C

    ham

    be r P

    a c e ma k e r R

    hy t h

    m

    Ven

    t r ic ula r

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 73

  • 74

    Du

    al-Ch

    amb

    er Pacem

    aker Rh

    ythm

    A

    trial and

    Ven

    tricular

    ECGS

    Atrial pacemake

    r spikeV

    entricular pacem

    aker spike

    No

    tes :

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 74

  • Pa c e m

    a k e r F a ilur e t o

    Ca p

    t ur e

    75

    ECGS

    Pacem

    aker M

    alfun

    ction

    sM

    alfun

    ction

    Reaso

    nFailu

    re to p

    aceP

    acemaker sp

    ikes are absen

    t. Th

    e cause m

    ay be a d

    ead b

    attery, a disru

    ptio

    n in

    the

    con

    nectin

    g w

    ires, or im

    pro

    per p

    rog

    ramm

    ing

    .Failu

    re to cap

    ture

    Pacem

    aker spikes are p

    resent, b

    ut n

    o P

    wave o

    r QR

    S fo

    llow

    s the sp

    ike. Turn

    ing

    up

    the p

    acemakers vo

    ltage o

    ften co

    rrects this p

    rob

    lem. Lead

    wires sh

    ou

    ld also

    be

    checked

    a d

    islod

    ged

    or b

    roken

    lead w

    ire may n

    ot d

    eliver the n

    eeded

    energ

    y.Failu

    re to sen

    seT

    he p

    acemaker fires b

    ecause it fails to

    detect th

    e hearts in

    trinsic b

    eats, resultin

    g in

    abn

    orm

    al com

    plexes. T

    he cau

    se may b

    e a dead

    battery, d

    ecrease of P

    wave o

    r QR

    Svo

    ltage, o

    r dam

    age to

    a pacin

    g lead

    wire. O

    ne serio

    us p

    oten

    tial con

    sequ

    ence m

    ayb

    e an R

    -on

    -T p

    hen

    om

    eno

    n.

    Oversen

    sing

    Th

    e pacem

    aker may b

    e too

    sensitive an

    d m

    isinterp

    ret mu

    scle mo

    vemen

    t or o

    ther

    events in

    the card

    iac cycle as dep

    olarizatio

    n. T

    his erro

    r resets the p

    acemaker in

    ap-

    pr o

    pr ia te ly , in

    c r e a s ing

    the a m

    ou

    nt o

    f time b

    e for e th

    e ne x t d

    is c ha r g

    e .

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 75

  • 76

    Pacem

    aker Failure to

    Sen

    seECGS

    Pa c e m

    a k e r Ov e r s e n

    s ing

    2142_Tab02_032-079.qxd 9/12/09 3:00 PM Page 76

  • Artifact

    A

    rtifacts are EC

    G d

    eflection

    s caused

    by in

    fluen

    ces oth

    er than

    the h

    earts electrical activity.

    Loo

    se Electro

    des

    77

    ECGS

    Ba s e lin

    e Va r ie s W

    it h R

    e s pir a t io

    n

    2142_Tab02_032-079.qxd 9/12/09 3:01 PM Page 77

  • 78

    60-Cycle In

    terference

    ECGS

    Re g u la r R-R in te rv a ls

    Mu

    s c le Ar t ifa c t

    Clin

    ical Tip:N

    ever con

    fuse m

    uscle artifact w

    ith A

    -fib if th

    e rhyth

    m is reg

    ular.

    2142_Tab02_032-079.qxd 9/12/09 3:01 PM Page 78

  • Notes:79

    ECGS

    2142_Tab02_032-079.qxd 9/12/09 3:01 PM Page 79

  • 12-LEAD

    80

    The 12-Lead ECG

    A standard 12-lead ECG provides views of the heart from 12 different angles.This diagnostic test helps to identify pathological conditions, especially bun-dle branch blocks and T wave changes associated with ischemia, injury, andinfarction. The 12-lead ECG also uses ST segment analysis to pinpoint thespecific location of an MI.

    The 12-lead ECG is the type most commonly used in clinical settings.The following list highlights some of its important aspects:

    The 12-lead ECG consists of the six limb leadsI, II, III, aVR, aVL, andaVFand the six chest leadsV1, V2, V3, V4, V5, and V6.

    The limb leads record electrical activity in the heart's frontal plane.This view shows the middle of the heart from top to bottom.Electrical activity is recorded from the anterior-to-posterior axis.

    The chest leads record electrical activity in the heart's horizontalplane. This transverse view shows the middle of the heart from left toright, dividing it into upper and lower portions. Electrical activity isrecorded from either a superior or an inferior approach.

    Measurements are central to 12-lead ECG analysis. The height anddepth of waves can offer important diagnostic information in certainconditions, including MI and ventricular hypertrophy.

    The direction of ventricular depolarization is an important factor indetermining the axis of the heart.

    In an MI, multiple leads are necessary to recognize its presence anddetermine its location. If large areas of the heart are affected, thepatient can develop cardiogenic shock and fatal arrhythmias.

    ECG signs of an MI are best seen in the reciprocal, or reflecting,leadsthose facing the affected surface of the heart. Reciprocal leadsare in the same plane but opposite the area of infarction; they show a"mirror image" of the electrical complex.

    Prehospital EMS systems may use 12-lead ECGs to discover signs ofacute MI, such as ST segment elevation, in preparation for in-hospitaladministration of thrombolytic drugs.

    After a 12-lead ECG is performed, a 15-lead, or right-sided, ECG maybe used for an even more comprehensive view if the right ventricle orthe posterior portion of the heart appears to be affected.

    2142_Tab03_080-093.qxd 9/12/09 2:15 PM Page 80

  • 81

    12-LEAD

    R Wave Progression

    Normal ventricular depolarization in the heart progresses from rightto left and from front to back.

    In a normal heart, the R wave becomes taller and the S wave smalleras electrical activity crosses the heart from right to left. This phenom-enon is called R wave progression and is noted on the chest leads.

    Alteration in the normal R wave progression may be seen in left ventric-ular hypertrophy, COPD, left bundle branch block, or anteroseptal MI.

    V1 V2 V3V4

    V5

    V6

    Leftlung

    Rightlung

    NNoorrmmaall RR wwaavvee pprrooggrreessssiioonn iinn cchheesstt lleeaaddss VV11VV66

    2142_Tab03_080-093.qxd 9/12/09 2:15 PM Page 81

  • 12-LEAD

    82

    Electrical Axis Deviation

    The electrical axis is the sum total of all electrical currents generatedby the ventricular myocardium during depolarization.

    Analysis of the axis may help to determine the location and extent ofcardiac injury, such as ventricular hypertrophy, bundle branch block,or changes in the position of the heart in the chest (e.g., from preg-nancy or ascites).

    The direction of the QRS complex in leads I and aVF determines theaxis quadrant in relation to the heart.

    30

    0180

    90

    90

    30

    60120

    150

    150

    III II

    I

    aVF

    aVR aVL

    II

    aVF

    I

    aVF

    aVF

    I

    aVF

    Normal A

    xis

    Right Axis Deviation

    Axi

    s De

    viation

    Extrem

    e Righ

    t Left Axis Deviation

    EElleeccttrriiccaall aaxxiiss ooff tthhee hheeaarrtt..

    CClliinniiccaall TTiipp:: Extreme right axis deviation is also called indeterminate,"no man's land," and "northwest."

    2142_Tab03_080-093.qxd 9/12/09 2:15 PM Page 82

  • 83

    12-LEAD

    Ischemia, Injury, and Infarction in Relation to the Heart

    Ischemia, injury, and infarction of cardiac tissue are the three stages result-ing from complete blockage in a coronary artery. The location of the MI iscritical in determining the most appropriate treatment and predicting prob-able complications. Each coronary artery delivers blood to specific areas ofthe heart. Blockages at different sites can damage various parts of theheart. Characteristic ECG changes occur in different leads with each typeof MI and can be correlated to the blockages.

    Anterior wall

    Anterior view

    LLooccaattiioonn ooff MMII bbyy EECCGG LLeeaaddss

    I lateral aVR V1 septal V4 anterior

    II inferior aVL lateral V2 septal V5 lateral

    III inferior aVF inferior V3 anterior V6 lateral

    Lateral wall

    Septal wall Inferior wall

    Anterior view Posterior view

    CClliinniiccaall TTiipp:: Lead aVR may not show any change in an MI.

    CClliinniiccaall TTiipp:: An MI may not be limited to just one region of the heart.For example, if there are changes in leads V3 and V4 (anterior) and leads I,aVL, V5, and V6 (lateral), the MI is called an anterolateral infarction.

    2142_Tab03_080-093.qxd 9/12/09 2:15 PM Page 83

  • 12-LEAD

    84

    Progression of an Acute Myocardial Infarction

    An acute MI is a c


Medical Physics Option Notes ECG - electrocardiogram.

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ANTHONY DAVIS: NOTES FROM THE UNDERGROUND · 4 5 By Anthony Davis In both Notes from the Underground and Wayang V for piano and orchestra I was interested in creating rhythmic drama,

ANTHONY DAVIS: NOTES FROM THE UNDERGROUND · 4 5 By Anthony Davis In both Notes from the Underground and Wayang V for piano and orchestra I was interested in creating rhythmic drama,

165A-notes - University of California, Davis

165A-notes - University of California, Davis

ECG NOTES. Conduction System Heart Beat Graphic from Boston Scientific International. Start the Heart.

ECG NOTES. Conduction System Heart Beat Graphic from Boston Scientific International. Start the Heart.

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HANDHELD ECG MONITOR - amperorblog.com Operation Manual... · V2.0E HANDHELD ECG MONITOR -3 -Notes on Safety This device is intended to monitor the ECG waveform, not for medical

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MAC 3500 resting ECG analysis system (1-07).pdf · GE Healthcare Fundamental fit MAC 3500 resting ECG analysis system Call 800-422-3547 For More Information Davis Medical Electronics,

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PowerNotes_Compiled_1.pdf - Davis School District / … · Web viewFERMENTATIONPower Notes FERMENTATION Power Notes Test Review: Photosynthesis and Cellular Respiration Name _____

The Main Applications of the ECG Nursing lecture notes

The Main Applications of the ECG Nursing lecture notes

Electrocardiography and Electroencephalographymacleod/bioen/be6460/notes/W12-ECG.pdf · ECG/EEG Bioengineering 6460 Bioelectricity Electrocardiography and Electroencephalography ECG/EEG

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Davis Family Genealogy Notes Family Genealogy Notes North Carolina Mark B. Arslan 407 Highlands Lake Drive Cary, NC 27518-9167 [email protected] Davis Web Site: 5 November 2006 NC,

Anatomy. ECG Electrodes ECG Waveform The 12 lead ECG.

Anatomy. ECG Electrodes ECG Waveform The 12 lead ECG.