Cardiac Pacemakers Step by Step

AN ILLUSTRATED GUIDE

S. Serge BaroldMD, FRACP, FACP, FACC, FESCProfessor of MedicineUniversity of South Florida College of Medicine J.A. Haley VA Medical CenterTampa, Florida, USA

Roland X. StroobandtMD, PhDAssociate Professor of CardiologyUniversity of LeuvenDepartment of CardiologyA.Z. Damiaan HospitalOostende, Belgium

Alfons F. Sinnaeveing.Professor Emeritus of Electronic EngineeringTechnical University KHBODepartment of ElectronicsOostende, Belgium

Cardiac Pacemakers Step by StepAN ILLUSTRATED GUIDE

To JennieSSB

To Miche, Serge, Frank & Mieke, GillRXS

To LieveAFS

Cardiac Pacemakers Step by Step

AN ILLUSTRATED GUIDE

S. Serge BaroldMD, FRACP, FACP, FACC, FESCProfessor of MedicineUniversity of South Florida College of Medicine J.A. Haley VA Medical CenterTampa, Florida, USA

Roland X. StroobandtMD, PhDAssociate Professor of CardiologyUniversity of LeuvenDepartment of CardiologyA.Z. Damiaan HospitalOostende, Belgium

Alfons F. Sinnaeveing.Professor Emeritus of Electronic EngineeringTechnical University KHBODepartment of ElectronicsOostende, Belgium

© 2004 S. Serge Barold, Roland X. Stroobandt and Alfons F. SinnaevePublished by Futura, an imprint of Blackwell Publishing

Blackwell Publishing, Inc., 350 Main Street, Malden, Massachusetts 02148-5020, USABlackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UKBlackwell Science Asia Pty Ltd, 550 Swanston Street, Carlton, Victoria 3053, Australia

All rights reserved. No part of this publication may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval systems, without permission in writing from the publisher, except by a reviewer who may quote brief passages in a review.

First published 2004Reprinted 2004

ISBN: 1-4051-1647-1

Library of Congress Cataloging-in-Publication Data

Barold, S. Serge. Cardiac pacemakers step by step : an illustrated guide/S. Serge Barold, Roland X. Stroobandt, Alfons F. Sinnaeve.—1st ed. p. ; cm.Includes bibliographical references and index. ISBN 1-4051-1647-11. Cardiac pacemakers—Pictorial works. [DNLM: 1. Cardiac Pacing, Artifi cial—methods. 2. Pacemaker, Artifi cial. 3. Electrocardiography—methods. WG 168 B264c 2004] I. Stroobandt, R. (Roland) II. Sinnaeve, Alfons F. III. Title. RC684.P3B365 2004 617.4’120645—dc22

2003020390

A catalogue record for this title is available from the British Library

Acquisitions: Jacques StraussProduction: Tom FryerTypesetter: Sparks Computer Solutions Ltd, in Great BritainPrinted and bound in Denmark by Narayana Press, Odder

For further information on Blackwell Publishing, visit our website:www.blackwellfutura.com

Notice: The indications and dosages of all drugs in this book have been recommended in the medical literature and conform to the practices of the general community. The medications described do not necessarily have specifi c approval by the Food and Drug Administration for use in the diseases and dosages for which they are recommended. The package insert for each drug should be consulted for use and dosage as approved by the FDA. Because standards for usage change, it is advisable to keep abreast of revised recommendations, particularly those concerning new drugs.

vContents

Atrial capture, 156

Automatic mode switching, 166

Pacemaker radiography, 174

Oversensing, 179

Troubleshooting, 184

Pacemaker hemodynamics and rate-adaptive pacing, 197

Pacemaker tachycardias—Part 1, 225

Pacemaker tachycardias—Part 2, 231

Treatment of tachycardia, 235

Pacemaker interference, 239

Biventricular pacing, 246

Pacemaker follow-up, 255

Conclusion, 287

Text: overview of cardiac pacemakers, 291

Index, 329

Preface, vii

What is a pacemaker? 1

Recording pacemaker activity, 2

Fundamentals of electricity, 10

Ventricular stimulation, 19

Pacing leads, 34

Sensing—basic concepts, 41

Sensing—advanced concepts, 60

Basic pacemaker electrocardiography, 73

Other single chamber pacemakers, 85

DDD pacemakers—basic functions, 88

DDD pacemakers—upper rate response, 106

Atrioventricular interval, 122

Retrograde ventriculoatrial synchrony in dual chamber pacemakers, 127

All dual chamber pacemakers function in the DDD mode, 140

Types of lower rate timing, 149

viiPreface

The impetus for writing this book came from our observations that many health care professionals and young physicians working in emergency rooms, intensive and coronary care units were unable to interpret simple pacemaker electrocardiograms correctly. Over the years we also heard many com-plaints from beginners in the fi eld of cardiac pacing that virtually all, if not all, the available books are too complicated and almost impossible to understand. Indeed, the ever-changing progress in electrical stimulation makes cardiac pacing a moving target. Therefore we decided to take up the challenge and write a book for beginners equipped with only a rudimentary knowledge of electrocardiography and no knowledge of cardiac pacing whatsoever. Because many individuals fi rst see the pacemaker patient after implantation, the book contains little about indications for pacing and implantation tech-niques. The book starts with basic concepts and pro-gressively covers more advanced aspects of cardiac pacing including troubleshooting and follow-up.

As one picture is worth a thousand words, this book tries to avoid unnecessary text and focuses on visual learning. We undertook this project with the premise that learning cardiac pacing should be enjoyable. Cardiac pacing is a logical discipline and should be fun and easy to learn with the carefully crafted illustrations in this book. The artwork is sim-ple for easy comprehension. Many of the plates are self-explanatory and the text in the appendix only intends to provide further details and a comprehen-sive overview.

Many of the images used to create the illustrations in this book are taken from CorelDraw and Corel Mega Gallery clipart collections.

We are grateful to Charlie Hamlyn of Blackwell Publishing and Tom Fryer of Sparks for their superb work in the production of this book.

S. Serge BaroldRoland X. Stroobandt

Alfons F. Sinnaeve

1

2

3

ECGPM

RALA

RL

LL

CONFIGURATION OF 12-LEAD ECGDURING TRANSVENOUS PACING

limbECG leads

limbECGleads

V1

pacing leadthrough

subclavian vein

pacing anode(skin electrode)

pacingcathode(insideheart)

V6

precordial ECGleads V1 to V6

A. F. Sinnaeve

4

midclavicularline

anterioraxillary

line

midaxillaryline

V14th intercostalspace at right

border ofsternum

V24th intercostalspace at left

border ofsternum

V45th intercostalspace at leftmidaxillary

lineV3

midwaybetweenpositions

2 & 4

V5same levelas pos. 4

in anterioraxillary line

V6same level

as pos. 4 & 5in midaxillary

line

STANDARD CHEST ELECTRODE POSITIONS

V7 in leftposterioraxillaryline

A. F. Sinnaeve

The right position of all the electrodes isextremely important !!!

5

6THE ELECTRICAL AXIS IN THE FRONTAL PLANE

R L

horizontalor

transversalplane

frontalplane

At any time during depolarization, there is a re-sultant instantaneous vector which representsthe electrical activity of the depolarization pro-cess of all the ventricular myocardium. As de-polarization proceeds, the magnitude and direc-tion of this instantaneous vector varies conti-nuously.The mean frontal plane vector or axis repre-sents the summation of all the instantaneousvectors recorded in the frontal plane that occurduring depolarization, and is depicted as asingle mean vector.

Why is the frontal plane axisimportant during pacing ?

Because it can help locate the 4 important sites ofstimulation which are the RV apex, RV outflow tract,LV and biventricular (i.e. simultaneous RV and LV)pacing.

To determine the mean frontal plane axis, you haveto understand the frontal plane diagram and arrange-ment of the frontal plane ECG leads. You also haveto understand the hemisphere concept of the variousfrontal plane ECG leads. If the mean QRS vector oraxis is situated in the positive (+) hemisphere of aparticular lead, this ECG lead will show a positive (+)deflection

A. F. Sinnaeve

Lead I will be positive if themean QRS vector is situatedin this hemisphere

Lead aVF will be positive if themean QRS vector is situatedin this hemisphere

I

aVF

Lead I will be negative if themean QRS vector is in thishemisphere

Lead aVF will be negativeif the mean QRS vector isin this hemisphere

I

IIIII aVF

aVLaVR

(0°)

(30°)

(60°)

(90°)(120°)

(150°)

(180°)

(- 30°)

(- 60°)(- 90°)

(- 120°)

(- 150°)

7

8

9

10

FUNDAMENTALS of ELECTRICITY

* Ohm’s law* Water equivalent* Impedance* Common units for pacemaker variables* Battery 1* Battery 2* Battery impedance and battery voltage* Battery capacity

UI RX

U

I

R

Pump

pump

pressure

waterflow

waterpipe

CAPACITYof the barrelin literΩ

11

Resis-tance

Current

Voltage

RU

I

OHM’s LAW

R

UI

= voltage (in volt V)

= current (in ampere A)

= resistance (in ohm )Ω

UI RX

UI RX

URX

URX

UI I X

Voltage Current Resistance

BATTERY

SOURCE LOAD

A. F. Sinnaeve

This is the most important lawof electricity !!!Everybody should be familiarwith these three variables,their relation and their units !

12

13

voltage U

current I

I

I

PACING IMPEDANCE

LEAD

TISSUE

VOLTAGE U (in volt)CURRENT I (in ampere)

comprises :* lead resistance* tissue impedance

NORMALPACING

IMPEDANCEca. 500Ω

INSULATIONDEFECT< 250Ω

LEADFRACTURE

> 1000Ω

R =

According to Ohm’s law :

A. F. Sinnaeve

Note for electricians :The pacing impedance is not purely resistive (the tissue impedance is capacitive)and should be indicated by a Z. In the clinical practice only the absolute value ormagnitude of the pacing impedance is considered and since it is expressed in“OHM” according to Ohm’s law, most people simply call it “resistance”

V

14COMMON UNITS FOR PACEMAKERS

VOLTAGEBasic unit : - symbol V

Sometimes used : - symbol mV

1 V = 1,000 mV or 1 mV =

volt

millivolt

Basic unit : - symbol

Sometimes used : - symbol k

1 = k or 1 k = 1,000 = 10

Ω

Ω

Ω Ω Ω Ω Ω

ohm

kilo-ohm

1

1

1

1

1,000

1,000

1,000

1,000,000

V

CURRENTBasic unit : - symbol A

Used stimulus amplitude : - symbol mA

1 A = 1,000 mA or 1 mA =

Used for battery current drain : - symbol A

1 A = 1,000,000 A or 1 A =

µ

µ µ

ampere

milliampere

microampere

A

A

= 10 V

= 10 A

= 10 A

- 3- 3

- 3

- 6

RESISTANCE

3

Learning how a pacemaker worksis overwhelming because I don’tknow anything about electricity !

It’s really simple because you only have tounderstand elementary concepts. You knowabout the flow of electrons in an electricalcircuit ? And do you remember Ohm’s law ?Just learn Ohm’s law and the units of current,voltage and resistance used in Ohm’s law.

You can forget parameters likeenergy (joules) and charge(coulombs) because they are notstrictly needed in the day-to-daypractice of pacemaker follow-up.

A. F. Sinnaeve

15

16

A. F Sinnaeve

Battery anode Electrolyte Battery cathodeOxidation Reduction

Solid LiI2Li 2Li + 2e+ I + 2e 2I2

LOADLoad

cathodeLoad

anode

Conventional current

I

I

I

I

I

I

I

Each atom of Liloses one electron

Each molecule of Icombines with two

electrons

Continuously formedby the reaction

between Li and I

electrons electrons

e e2Li + I = 2LiI2

The Lithium - Iodine battery

How about the lithium-iodine battery ? Someone toldme that no electrons can flow through that battery ?

Yes, that’s true, but it isn’t difficult to understand. The anode of a lithium-iodinebattery is the place where electrons free themselves from lithium atoms to formLi ions. W as an electron barrier and allelectrons being negative and repelling each other, the electrons are pushed out-side the battery to start their journey through the electrical circuit.Following the electrical conductors, the electrons enter the load via its cathode.Just as a liquid, electricity cannot be compressed. So, an equal amount of elec-trons is leaving the load via its anode, being attracted by the positive pole of thebattery. The electrons enter the battery cathode where they combine with iodineI to form 2I ions.Inside the battery, the electrical circuit is closed by the flow of the Li and I ions.These ions attract each other and diffuse through the electrolyte. When the twokinds of ions meet each other, they combine to form lithium-iodide LiI.However, the lithium-iodide is not a good electrical conductor and so the buildupof this LiI increases the internal resistance of the battery.

ith the electrolyte of the battery serving+

+-

-2

17The Lithium - Iodine battery

The anode of the battery produces lithium ions, while the cathode is producingiodine ions. These ions are moving to the other pole of the battery and are recom-bining to lithium iodide (LiI). This discharge product forms a barrier for the furthermovement of ions and thus an internal battery resistance is built up.At the BOL the electrolyte barrier is thin with a low normal impedance. However,at the EOL the layer becomes thick and when the cathode material is almostdepleted, the internal resistance is very high.

battery voltage

time

3V

2V

1V

30 60 90 120 months

2.8V

internal DC resistance

15 k Ω

10 k Ω

5 kΩ

Central lithium anode(ribbed & corru-gated to increasesurface area)

Connectingwire

Connectorto the anode

Glass-to-metalseal

Connector tothe cathode

Cathode(complex of

iodine andpolyvinyl-pyridine)

Stainless steelencapsulation

and cathodecurrent collector

A. F. Sinnaeve

BOL = EOL =beginning-of-life ; end-of-life

18

CAPACITYof the barrel

in liter

OUTFLOW = DRAINliter

minute

CAPACITYof the battery

in ampere.hour(Ah)

circuitry

CURRENT DRAIN (in ampere A)(1 ampere = 1,000,000 A)

(1A = 10 A)µ

µ6

BATTERY CAPACITY & LONGEVITY

LIFE EXPECTANCY =capacity

drain

CAPACITY : 60 litersDRAIN : 0.5 liters/minuteEXPECTED TIME to emptythe barrel:

e.g.

600.5

= 120 minutes

= 2 hours

CAPACITY : 2 ampere.hours = 2 AhDRAIN : 25 A = 25

= 0.000025 AEXPECTED LIFE TIME of the battery :

µ MICROAMPEREe.g.

2 Ah0.000025 A

= 80,000 hours

= about 9 years

A. F. Sinnaeve

full of water

The output current of the pulses to the heart is expressed in mA (1 mA = 1/1,000 A)The current drain of the battery is expressed in A (1 A = 1/1,000.000 A)

1 milliampere (mA) = 1,000 microampere ( A)µ

µµ

Battery life expectancy increases if the current drain decreases by using :* pulses with a smaller voltage amplitude* pulses with a shorter duration

Hence the importance of determining the chronic pacing threshold so asto program the output voltage and pulse duration to provide an adequatesafety margin and also conserve battery capacity to extend battery life

19

20