Download Arrhythmias in Children - Jacobi Emergency Medicine

Arrhythmias in
Children:
Assessment and
Management
Robert H. Pass, MD
Director, Pediatric Cardiac
Electrophysiology
Montefiore Medical
Center – Albert Einstein
College of Medicine
Pediatric Arrhythmia Management
• Bradycardia
(“Boring”)
vs.
• Tachycardias
(“Exciting”)
Disorders of Automaticity
Disorders of Reentry
Pediatric Arrhythmia Management
• Normal Cardiac
Conduction System –
Electrical Anatomic
Substrate
Bradyarrhythmias
• Sinus Node Dysfunction:
– Rare in patients with
structurally normal hearts
– Commonly seen following
palliative congenital heart
surgery:
• Acutely:
– AV Canal Repairs
– Sinus Venosus ASD repair
• Chronically:
– Mustard/Senning Repair
of DTGA
– Fontan Palliation of
Single Ventricular hearts
Bradyarrhythmias
Mustard Procedure for D-Transposition of the Great
Arteries
Bradyarrhythmias
• 75% of all
DTGA patients
undergoing
Mustard at
Columbia not in
sinus rhythm at
follow-up
Bradyarrhthmias
• Conduction
Block
________
______________
_________
_______________
______________
Bradyarrhythmias
• Causes of Block:
Infectious:
Inflammatory:
Trauma:
Neurodegenerative:
Infiltrative disorders:
Pharmacologic:
Viral myocarditis
Lyme Disease
Chagas Disease
Rheumatoid arthritis
Cardiac Surgery
Radiation therapy
Myotonic dystrophy
Kearns-Sayre syndrome
Tuberous Sclerosis
Amyloidosis
Tricyclic antidepressants
Digoxin
Diptheria
Endocarditis
Guillain-Barre
Blunt chest trauma
Muscular dystrophy
Lymphoma
Sarcoid
Antiarrhythmic agents
Clonidine
Bradyarrhythmias
• Clinical Examples
 7 year old with history of severe cold symptoms,
lethargy, dyspnea and echocardiogram
demonstrated severe ventricular dysfunction
Bradyarrhythmias
• Clinical Examples
8 year old referred to cardiology for
evaluation of heart murmur
Bradyarrhythmias
• Treatment:
- Treat underlying
problem
- If postoperative
CHB or due to
irreversible cause,
pacemaker
implantation
Bradyarrhythmias
9 Months old
•
30 Months old
Transvenous Pacemaker in Infant – “Loop” technique
(from Spotnitz et al. Annals of Thoracic Surgery , 1991)
Tachyarrhythmias
• Disorders of Automaticity
VS.
• Disorders of Reentry
Tachyarrhythmias - Automatic
• Common characteristics of automatic
arrhythmias include:
- “heat up” / “cool down”
- No abrupt onset or offset
- Cannot be DC cardioverted
- Very catecholamine sensitive
Tachyarrhythmias - Automatic
• Clinical Examples of Automatic
Tachyarrhythmias:
- Sinus tachycardia
- Ectopic atrial tachycardia (EAT)
- Junctional Ectopic Tachycardia (JET)
- Some types of VT
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 rhythm
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
function
Tachyarrhythmias - Automatic
• EAT – Ectopic Atrial
Tachycardia
• Atrial ectopy from a
single area of atrial
myocardium other
than sinus node
• Commonly results in
ventricular dysfunction
Tachyarrhythmias - Automatic
• Clinical Example
5 mo s/p
Tetralogy of
Fallot repair –
postoperative
hour 4
JET !!!!!!!
Tachyarrhythmias - Automatic
• Clinical Example:
15 year old with
history of VT –
noncompliant
with medication
ER 1999
Tachyarrhythmias - Reentry
• Reentry
•
1.
2.
3.
- represents 90% of SVT
in pediatric populations
3 Major Requirements:
2 pathways connected
proximally and distally
Unidirectional block in
one pathway
A zone of slow conduction
Tachyarrhythmias - Reentry
• Reentry
General Characteristics:
1. Rhythm can be initiated and terminated
with appropriately timed premature beats.
2. Abrupt onset and termination.
3. Successful termination (at least temporarily)
with DC cardioversion
Tachyarrhythmias - Reentry
• Reentry
Clinical examples of reentry include:
- Accessory pathway (“bypass tract”)
mediated tachycardia (e.g. WPW)
- AV nodal reentry (AVNRT)
- Atrial Flutter
- Some ventricular tachycardias
Tachyarrhythmias - Reentry
• Accessory pathway
tachycardia is most
common etiology of
tachycardia in children
• More common in males
• Typical route is from atria
to ventricles via AV node
and retrograde via
accessory pathway –
Orthodromic
Reentrant
Tachycardia (ORT)
Tachyarrhythmias - Reentry
• Clinical example :
15 year old boy with history of Ebstein’s anomaly
and intermittent palpitations
Tachycardia
Sinus Rhythm
Tachyarrhythmias - Reentry
• Peak age for occurrence of SVT/ORT is first
2 months of age – 40% of first episodes
occur this early in life
• Frequency 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
testing
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 life
• Reasons for this finding unclear
Tachyarrhythmias - Reentry
• WPW – Paradigm of ORT
• First described in 1930
• Short PR interval, bundle branch
block on resting surface ECG
and intermittent tachycardia
• Presence of delta wave –
ventricular preexcitation
• Risk of sudden death ~ 1.5/1000
pt. years
Tachyarrhythmias - Reentry
• Clinical example:
15 year old boy with insignificant past
medical history seen in ER with palpitations
and dizziness
Tachyarrythmias - Reentry
Acute therapy was administered:
Tachyarrhythmias - Reentry
• ECG s/p DC Cardioversion
• Wolff Parkinson White Syndrome!
Tachyarrhythmias - WPW
• Mechanism of
arrhythmia is
preexcited atrial
fibrillation
• Most common
cause of sudden
death in WPW
Tachyarrhythmias - WPW
• WPW – Key points:
1. Risk of death is not from SVT/ORT but
instead from rapidly conducted A fib (rare in
infants).
2. Digoxin/Verapamil are contraindicated in
older patients.
3. Parent education about identifying
tachycardia critical.
Tachyarrhythmias - Reentry
• 16 year old with palpitations and dizziness 10
years s/p Fontan palliation for tricuspid
atresia
Tachyarrhythmias - Reentry
• Intraatrial Reentrant Tachycardia
(IART):
- Common problem affecting 12.5-26% of
patients with repaired/palliated CHD at
intermediate and long-term follow-up
- Particular problem among Fontan
patients
Tachyarrhythmias - Reentry
• IART is virtually universal following Fontan
(from Fishberger et al. JTCVS, 1997)
Tachyarrhythmias - Reentry
• Typical IART
reentrant loop
due to scarring in
postoperative
children
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
VT/VF
Tachyarrhythmias - Treatment
• Chronic/”Definitive” therapy:
Drug therapy – in general, for most forms of
SVT, drugs are effective
Most commonly used agents:
Digoxin
Sotalol
Procainamide
Amiodarone
Betablockers
Flecainide
Verapamil
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 blockade
• Not as commonly used due to potent negative
inotropy – also shown to be associated with
cardiovascular collapse in infants
Tachyarrhythmias – Drug Therapy
• Chronic Therapy: (Infancy)
– Digoxin
• Useful antiarrhythmic agent in infants
• Causes AV nodal slowing and reduces atrial ectopy
• Dosing from 8-14 mcg/kg/day divided bid
– Beta Blockers
•
•
•
•
Useful alternative antiarrhythmic agent in infants
Causes AV nodal slowing and reduces atrial ectopy
Commonly used agent is Inderal
Associated with low blood glucose levels – “D sticks” must be
monitored initially
Arrhythmias – Drug Therapy
• Chronic Therapy – Children and
Adolescents:
– Beta blockade – effective about 60-75%
• Low side effect profile
– Calcium channel blockers – similar efficacy
• Low side effect profile (e.g. Verapamil)
– Digoxin – not as effective in older patients as in
infancy and thus not typically used in this age
range
Arrhythmias – Drug Therapy
• Chronic Therapy – When the “SIMPLE STUFF”
doesn’t work:
– Sotalol
•
•
•
•
Class III agent
Potent beta blocker
High incidence of proarrhythmia (~ 10%)
Significantly more effective than “simple” agents
– Flecainide
• Class Ib agent
• Very effective
• ? High incidence of proarrhythmia (CAST study)
Arrhythmias – Drug Therapy
• Amiodarone
– Class III agent (“all 4 Vaughn Williams
classification effects”)
– Very effective agent
– Very long half life (~ 45 days)
– Low incidence of proarrhythmia
– High side effect profile
• Pulmonary Liver Thyroid
• Eye GI tract
Skin
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
death
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 abstract
Tachyarrhythmias - Therapy
• Radiofrequency Catheter Ablation
(RFCA)
• Advantages:
Potentially “Definitive” therapy
Drug use often not required following
procedure
Tachyarrhythmias - Therapy
• RFCA technical
considerations
• Minimum of 4-5 catheters
• 2-3 cardiologists
• 1 nurse/1 CV tech
• Computerized on-line
analysis
• Fluoroscopy
• Programmable stimulator
Tachyarrhythmias - Therapy
• Simplified example of successful ablation of left
sided EAT focus in 5 year old
Tachyarrhythmias - Therapy
•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%
Diagnosis
Success (%)
WPW
Concealed AP
PJRT
EAT
Mahaim
AVNRT
Totals
94
99
95
100
100
83
90
Tachyarrhythmias - Therapy
• Risks associated with RFCA:
– Normal cath risks: bleeding, stroke,
infection
– Serious complications (death, ventricular
dysfunction, CVA, cardiac perforation)
• Occurred 1.2% of time in Tanel, Boston
Children’s Study (1997)
Tachyarrhythmias - Therapy
• Angiogram of Fontan – GIGANTIC RA –
“so much ground to cover”
Tachyarrhythmias - Therapy
• Data for standard RFCA of IART have been
generally poor using standard techniques
• ~ 50% arrhythmia free at 2 years follow-up
• In light of these findings, interest in newer
mapping techniques are growing
Tachyarrhythmias - Therapy
Newer Mapping
Strategies
Carto – Biosense
Electroanatomical
Mapping System
Tachyarrhythmias – New Mapping
Strategies
• Electroanatomical Mapping – Non Contact
– Endocardial Solutions
9 French
Balloon Catheter
Tachyarrhythmias – Newer
Therapies
• Newer “Chilli” catheters – allowing larger
and deeper radiofrequency lesions for IART
in Fontan patients
Cryoablation – Smaller “reversible”
lesions
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