Arrhythmias in Children: - PowerPoint Presentation

Slide1

Arrhythmias in Children:Assessment and Management

Robert H. Pass, MDDirector, Pediatric Cardiac ElectrophysiologyMontefiore Medical Center – Albert Einstein College of MedicineSlide2

Pediatric Arrhythmia Management

Bradycardia(“Boring”) vs.Tachycardias(“Exciting”)

Disorders of AutomaticityDisorders of ReentrySlide3

Pediatric Arrhythmia Management

Normal Cardiac Conduction System – Electrical Anatomic SubstrateSlide4

Bradyarrhythmias

Sinus Node Dysfunction:Rare in patients with structurally normal heartsCommonly seen following palliative congenital heart surgery:Acutely:AV Canal RepairsSinus Venosus ASD repairChronically:

Mustard/Senning Repair of DTGAFontan Palliation of Single Ventricular heartsSlide5

Bradyarrhythmias

Mustard Procedure for D-Transposition of the Great ArteriesSlide6

Bradyarrhythmias

75% of all DTGA patients undergoing Mustard at Columbia not in sinus rhythm at follow-upSlide7

Bradyarrhthmias

Conduction Block

________

______________

_________

_______________

______________Slide8

Bradyarrhythmias

Causes of Block:

Infectious: Viral myocarditis Diptheria Lyme Disease Endocarditis Chagas DiseaseInflammatory: Rheumatoid arthritis Guillain-Barre

Trauma: Cardiac Surgery Blunt chest trauma

Radiation therapy

Neurodegenerative: Myotonic dystrophy Muscular dystrophy

Kearns-Sayre syndrome

Infiltrative disorders: Tuberous Sclerosis Lymphoma

Amyloidosis Sarcoid

Pharmacologic: Tricyclic antidepressants Antiarrhythmic agents

Digoxin ClonidineSlide9

Bradyarrhythmias

Clinical Examples7 year old with history of severe cold symptoms, lethargy, dyspnea and echocardiogram demonstrated severe ventricular dysfunctionSlide10

Bradyarrhythmias

Clinical Examples8 year old referred to cardiology for evaluation of heart murmurSlide11

Bradyarrhythmias

Treatment: - Treat underlying problem - If postoperative CHB or due to irreversible cause, pacemaker implantationSlide12

Bradyarrhythmias

9 Months old

30 Months old

Transvenous Pacemaker in Infant – “Loop” technique

(

from Spotnitz et al. Annals of Thoracic Surgery , 1991

)Slide13

Tachyarrhythmias

Disorders of Automaticity VS.Disorders of ReentrySlide14

Tachyarrhythmias - Automatic

Common characteristics of automatic arrhythmias include: - “heat up” / “cool down” - No abrupt onset or offset - Cannot be DC cardioverted - Very catecholamine sensitiveSlide15

Tachyarrhythmias - Automatic

Clinical Examples of Automatic Tachyarrhythmias: - Sinus tachycardia - Ectopic atrial tachycardia (EAT) - Junctional Ectopic Tachycardia (JET) - Some types of VTSlide16

Tachyarrhythmias

Disorders of automaticity: “Whatever is fastest in the heart wins’”In automatic arrhythmias, an area of myocardium with calcium channel cells fires at a rate that is faster than the sinus node and therefore controls the rhythmSlide17

Tachyarrhythmias - Automatic

Clinical Example: 14 year old girl seen by pediatrician who heard irregular heart beat and obtained ECG; recent history of fainting without palpitations; Echocardiogram demonstrated severely depressed functionSlide18

Tachyarrhythmias - Automatic

EAT – Ectopic Atrial TachycardiaAtrial ectopy from a single area of atrial myocardium other than sinus nodeCommonly results in ventricular dysfunctionSlide19

Tachyarrhythmias - Automatic

Clinical Example 5 mo s/p Tetralogy of Fallot repair – postoperative hour 4JET !!!!!!!Slide20

Tachyarrhythmias - Automatic

Clinical Example: 15 year old with history of VT – noncompliant with medication

ER 1999Slide21

Tachyarrhythmias - Reentry

Reentry - represents 90% of SVT in pediatric populations3 Major Requirements:2 pathways connected proximally and distally

Unidirectional block in one pathwayA zone of slow conductionSlide22

Tachyarrhythmias - Reentry

ReentryGeneral Characteristics:Rhythm can be initiated and terminated with appropriately timed premature beats.Abrupt onset and termination.Successful termination (at least temporarily) with DC cardioversionSlide23

Tachyarrhythmias - Reentry

ReentryClinical examples of reentry include:Accessory pathway (“bypass tract”) mediated tachycardia (e.g. WPW)AV nodal reentry (AVNRT)Atrial FlutterSome ventricular tachycardiasSlide24

Tachyarrhythmias - Reentry

Accessory pathway tachycardia is most common etiology of tachycardia in childrenMore common in malesTypical route is from atria to ventricles via AV node and retrograde via accessory pathway – O

rthodromic Reentrant Tachycardia (ORT)Slide25

Tachyarrhythmias - Reentry

Clinical example : 15 year old boy with history of Ebstein’s anomaly and intermittent palpitations

Tachycardia

Sinus RhythmSlide26

Tachyarrhythmias - Reentry

Peak age for occurrence of SVT/ORT is first 2 months of age – 40% of first episodes occur this early in lifeFrequency decreases over first year of life – 2/3 of infants no longer have clinical tachycardia at age 1 year and 1/3 have no evidence of accessory pathway conduction at one year by formal transesophageal testingSlide27

Tachyarrhythmias - Reentry

Other peaks for tachycardia recurrence are 5-8 years and 10-15 years~ 40% of patients with tachycardia as young infants will recur some time in lifeReasons for this finding unclearSlide28

Tachyarrhythmias - Reentry

WPW – Paradigm of ORTFirst described in 1930Short PR interval, bundle branch block on resting surface ECG and intermittent tachycardiaPresence of delta wave – ventricular preexcitationRisk of sudden death ~ 1.5/1000 pt. yearsSlide29

Tachyarrhythmias - Reentry

Clinical example: 15 year old boy with insignificant past medical history seen in ER with palpitations and dizzinessSlide30

Tachyarrythmias - Reentry

Acute therapy was administered

:Slide31

Tachyarrhythmias - Reentry

ECG s/p DC CardioversionWolff Parkinson White Syndrome!Slide32

Tachyarrhythmias - WPW

Mechanism of arrhythmia is preexcited atrial fibrillationMost common cause of sudden death in WPW

Preexcited A FibSlide33

Tachyarrhythmias - WPW

WPW – Key points:Risk of death is not from SVT/ORT but instead from rapidly conducted A fib (rare in infants).Digoxin/Verapamil are contraindicated in older patients.Parent education about identifying tachycardia critical.Slide34

Tachyarrhythmias - Reentry

16 year old with palpitations and dizziness 10 years s/p Fontan palliation for tricuspid atresiaSlide35

Tachyarrhythmias - Reentry

Intraatrial Reentrant Tachycardia (IART):

Common problem affecting 12.5-26% of patients with repaired/palliated CHD at intermediate and long-term follow-upParticular problem among Fontan patientsSlide36

Tachyarrhythmias - Reentry

IART is virtually universal following Fontan (from Fishberger et al. JTCVS, 1997)Slide37

Tachyarrhythmias - Reentry

Typical IART reentrant loop due to scarring in postoperative childrenSlide38

Tachyarrhythmias – Summary of Mechanisms

Level of Heart

Automaticity

Reentry

SA Node

Sinus tachycardia

SA node reentry

Atrial muscle

EAT/MAT

Aflutter/Afib

AV Node

JET

AVNRT

AV reciprocating

NA

WPW/

Concealed AP

Ventricles

VT/VF

VTSlide39

Tachyarrhythmias - Treatment

Chronic/”Definitive” therapy:Drug therapy – in general, for most forms of SVT, drugs are effectiveMost commonly used agents: Digoxin Sotalol Procainamide Amiodarone

Betablockers Flecainide VerapamilSlide40

Tachyarrhythmias – Drug Therapy

Acute therapy:IV adenosine – causes transient AV nodal blockade Particularly useful for AV reciprocating tachycardias such as ORT or AVNRT (2 most common SVT’s in children)IV verapamil – also causes AV nodal blockadeNot as commonly used due to potent negative inotropy – also shown to be associated with cardiovascular collapse in infantsSlide41

Tachyarrhythmias – Drug Therapy

Chronic Therapy: (Infancy)DigoxinUseful antiarrhythmic agent in infantsCauses AV nodal slowing and reduces atrial ectopyDosing from 8-14 mcg/kg/day divided bidBeta Blockers

Useful alternative antiarrhythmic agent in infantsCauses AV nodal slowing and reduces atrial ectopyCommonly used agent is InderalAssociated with low blood glucose levels – “D sticks” must be monitored initiallySlide42

Arrhythmias – Drug Therapy

Chronic Therapy – Children and Adolescents:Beta blockade – effective about 60-75%Low side effect profileCalcium channel blockers – similar efficacyLow side effect profile (e.g. Verapamil)Digoxin – not as effective in older patients as in infancy and thus not typically used in this age rangeSlide43

Arrhythmias – Drug Therapy

Chronic Therapy – When the “SIMPLE STUFF” doesn’t work:Sotalol Class III agentPotent beta blockerHigh incidence of proarrhythmia (~ 10%)Significantly more effective than “simple” agents

FlecainideClass Ib agentVery effective? High incidence of proarrhythmia (CAST study)Slide44

Arrhythmias – Drug Therapy

AmiodaroneClass III agent (“all 4 Vaughn Williams classification effects”)Very effective agentVery long half life (~ 45 days)Low incidence of proarrhythmiaHigh side effect profilePulmonary Liver Thyroid Skin

Eye GI tractSlide45

Tachyarrhythmias - Therapy

Drugs are not a “free ride” - Side effects (cardiac and non-cardiac) - Proarrhythmia - Not always efficacious - Compliance

-? Lifelong usage - For WPW, may not reduce risk of sudden deathSlide46

Tachyarrhythmias - Therapy

Drug therapy for IART “stinks” -% freedom from recurrence of IART on various antiarrhythmic agents in patients s/p CHD surgery

from Weindling et al. – Unpublished abstractSlide47

Tachyarrhythmias - Therapy

Radiofrequency Catheter Ablation (RFCA)Advantages:Potentially “Definitive” therapyDrug use often not required following procedure Slide48

Tachyarrhythmias - Therapy

RFCA technical considerationsMinimum of 4-5 catheters2-3 cardiologists1 nurse/1 CV techComputerized on-line analysisFluoroscopyProgrammable stimulatorSlide49

Tachyarrhythmias - Therapy

Simplified example of successful ablation of left sided EAT focus in 5 year oldSlide50
Slide51

Tachyarrhythmias - Therapy

Diagnosis Success (%)WPW 94Concealed AP 99PJRT 95EAT 100Mahaim 100

AVNRT 83Totals 90

RFCA Success Rates are quite high !

(Boston Children’s Data –

J Peds

1997)

Data from Children’s Hospital at Montefiore for past 3 years – overall success rate ~ 94%Slide52

Tachyarrhythmias - Therapy

Risks associated with RFCA:Normal cath risks: bleeding, stroke, infectionSerious complications (death, ventricular dysfunction, CVA, cardiac perforation)Occurred 1.2% of time in Tanel, Boston Children’s Study (1997)Slide53

Tachyarrhythmias - Therapy

Angiogram of Fontan – GIGANTIC RA – “so much ground to cover”Slide54

Tachyarrhythmias - Therapy

Data for standard RFCA of IART have been generally poor using standard techniques~ 50% arrhythmia free at 2 years follow-upIn light of these findings, interest in newer mapping techniques are growingSlide55

Tachyarrhythmias - Therapy

Carto – Biosense

Electroanatomical

Mapping System

Newer Mapping

StrategiesSlide56

Tachyarrhythmias – New Mapping Strategies

Electroanatomical Mapping – Non Contact – Endocardial Solutions

9 French

Balloon CatheterSlide57

Tachyarrhythmias – Newer Therapies

Newer “Chilli” catheters – allowing larger and deeper radiofrequency lesions for IART in Fontan patientsSlide58

Cryoablation – Smaller “reversible” lesionsSlide59

Tachyarrhythmias – New Directions

Refining of newer mapping strategies for better understanding of scar anatomy and its relationship to IART Newer surgical approaches to congenital surgery to reduce rates of IART or to treat it (cryosurgery)New catheter design to lower cath-related risks of RFCA (e.g. Cryocatheters)Use of low fluoroscopy protocols and 3 D electroanatomical mapping techniques to reduce exposure to ionizing radiation