Transcript teixeira---cardiac-arrhythmia-in-children

Cardiac arrhythmias in children:
emphasis on SVT
Definition, identification and management
Otto H. P. Teixeira, MD, FRCPC, FACC
Conduction system of the heart
What is an
arrhythmia?
An arrhythmia is an abnormal heart rhythm
• Sinus arrhythmia
• Premature ventricular beats (PVCs)
• Premature atrial beats (PACs)
What is an
Arrhythmia?
• An arrhythmia is an
abnormal heart rhythm
What is an
Arrhythmia?
• An arrhythmia is an
abnormal heart rhythm
• Bradycardia is when the
heart rate is too
slow
What is an
Arrhythmia?
• An arrhythmia is an
abnormal heart rhythm
• Bradycardia is when the
heart rate is too
slow
• Tachycardia is when the
heart rate is too
fast for the age
Normal heart rates in children
Nelson Textbook of Pediatrics 19th ed.
Elsevier/Saunders 2011: 1613-16
AGE
Premature
0-3 mo
3-6 mo
6-12 mo
1-3 yr
3-6 yr
6-12 yr
12+yr
HEART RATE
120-170*
100-150*
90-120
80-120
70-110
65-110
60-95
55-85
Cardiac arrhythmia in children
What's "too slow" ?
• newborn: less than 80 beats a minute.
• a trained teenage athlete: 50 beats a minute
Cardiac arrhythmia in children
Symptoms of bradycardia
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Fatigue
Dizziness
Lightheadedness
Fainting or near-fainting spells
In extreme cases, cardiac arrest occur
Supraventricular tachycardia (SVT)
All forms of tachycardia except VT *
* Van Hare G. Supraventricular tachycardia. In: Kliegman, Stanton, St. Geme,
Schor, Behrman, eds. Nelson Textbook of Pediatrics 19th ed.
Elsevier/Saunders 2011: 1613-16
SVT in children
 Most common form of tachycardia in
children:
 1 : 250-1000 (Gillette & Garson)
SVT in children
 Most common form of tachycardia in
children:
 1 : 250-1000 (Gillette & Garson)
 Narrow QRS complexes often with no
discernible “P” wave
 HR: 150-300 bpm and unvarying
Mechanisms of Arrhythmias
Classifying tachycardia:
frequency
Common:
AV reentry
Less common:
atrial
Uncommon:
AV node reentry
Rare:
other
SVT in children
Re-entrant:
with accessory pathway
without pathway
SVT in children
Re-entrant:
with accessory pathway
without pathway
Ectopic or automaticity: AET, JET
AV re-entrant tachycardias
Reentry: most common etiology in children
AVRT, AVNRT: age dependent
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Narrow QRS: usual
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1:1 AV conduction: usual
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Sudden onset and cessation
SVT in children
Etiology
Reentry:
AVRT: most common in infants
Accessory connection anywhere
in the AV ring - WPW, Mahaim
tracts, others
AVNRT: adolescents and adults
AV peri-nodal area: dual AV node
“slow-fast” AV node tracts
SVT in children
HR 215, occasional “P wave” seen
SVT in children
HR 187 bpm: P waves not discernible
AV re-entrant tachycardias
• WPW: 1 : 1000
• 25 % of SVT

orthodromic: narrow QRS during
tachycardia

antidromic: broad QRS
(indistinguishable from
VT)
WPW
AV re-entrant tachycardias
Orthodromic tachycardia
using an accessory
pathway in WPW
Activation: AV node, HisPurkinje system, ventricle,
accessory pathway, atria. P
wave closely follows the
QRS PR > RP
AV re-entrant tachycardias
Antidromic tachycardia:
antegrade conduction may lead
to atrial fibrillation and VF:
risk of SCD
AV nodal re-entrant tachycardia:
AVNRT
 Dual pathways within the AV node
“slow-fast” AV nodal tracts
More common in adolescents and adults
May cause syncope
May respond to beta blockers and
ablation*
* Teixeira OH, Bilaji, Gillette PC. RF catheter ablation of
atrioventricular nodal reentrant tachycardia in children. PACE 1994;
17:1621-1626.
Management: SVT in children
 Evaluate
General: IV, O2, capillary filling, BP
12-lead ECG (may double speed):
REENTRY?
Stable?
1. Vagal maneuvers: infant - modified diving
reflex (ice to face); older - gag, head
immersion in water, Valsalva
Management (cont’d)
2. Adenosine:
0.1 mg/kg mx 6 mg
ECG rhythm should be running
Management (cont’d)
• Adenosine:
0.1 mg/kg mx 6mg. ECG rhythm
should be running
f a i l e d!?
• Check tracing: reentry? check IV
Double dose to mx. 12 mg
Management (cont’d)
3. Consider synchronized DC cardioversion:
0.5-2 Joules/kg
failed!?
• Check: equipment, paddles, position,
coupling gel, contact
• Repeat: double dose
4. Overdrive pacing: PM, esophageal lead
5. Other drugs:
• Amiodarone:
5 mg/kg IV over 20-60 min
• Procainamide:
15 mg/kg IV over 30-60 min
Question
• One month-old male with narrow QRS heart
rate of 320 bpm and tachypnea, poor
peripheral pulse. Your treatment of choice
includes all, EXCEPT:
• 1. Vagal maneuvers, ie, ice to face.
Question
• One month-old male with narrow QRS heart
rate of 320 bpm and tachypnea, poor
peripheral pulse. Your treatment of choice
includes all, EXCEPT:
• 1. Vagal maneuvers, ie, ice to face.
• 2. Adenosine 0.1-0.2 mg/Kg IV push
Question
• One month-old male with narrow QRS heart
rate of 320 bpm and tachypnea, poor
peripheral pulse. Your treatment of choice
includes all, EXCEPT:
• 1. Vagal maneuvers, ie, ice to face.
• 2. Adenosine 0.1-0.2 mg/Kg IV push
• 3. Verapamil 0.1 mg/Kg IV push
Question
• One month-old male with narrow QRS heart
rate of 320 bpm and tachypnea, poor
peripheral pulse. Your treatment of choice
includes all, EXCEPT:
• 1. Vagal maneuvers, ie, ice to face.
• 2. Adenosine 0.1-0.2 mg/Kg IV push
• 3. Verapamil 0.1 mg/Kg IV push
• 4. Synchronized DC cardioversion: 0.5-1.0 J/Kg
SVT in children
Etiology
Automaticity:
atrial ectopic tachycardia
(AET)
junctional ectopic
tachycardia (JET)
Ectopic or automaticity: AET, JET
AET
 Atrial automatic focus: incessant , may be
associated with cardiac dysfunction
 Insidious onset with “warm-up” and
“cool-down”
 Abnormal “P” wave axis and PR interval
 Rate variation
 May have periods of sinus rhythm during
sleep: P changes
The P wave morphology depends on the position of the focus
May appear like sinus tachycardia: RP interval is longer than
the PR.
The P waves may be blocked (not shown).
AET
AET
• Rarely needs emergency treatment
• Adenosine may work and helps diagnosis:
P waves revealed during adenosine induced AV block
Inappropriate sinus tachycardia (Bauernfeind R et al An
Intern Med 1979; 91:702-710)
Chaotic or multifocal AET
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> 3 ectopic Ps
Frequent blocked Ps
Varying PR
Occurs mostly in infants < 1 yr
Difficult single drug management
May improve spont by 3 yr of age
Chaotic or multifocal AET
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> 3 ectopic Ps
Frequent blocked Ps
Varying PR
Occurs mostly in infants < 1 yr
Difficult drug management
May improve spont by 3 yr of age
JET
• Uncommon; often post-op
• EKG: narrow QRS with V rate faster than A,
and AV dissociation
• Diff. to distinguish from VT: ”Why?”
• Rates 180-240 bpm
• Congenital: rare may be seen pre-natally: HR
370 bpm
JET
First-degree AV block is
typical and 2nd-degree AVB
is common. The tachycardia
and degree of AV block are
influenced by the autonomic
tone
 Lead II of a ECG from a patient
with postoperative JET. “Ps”
are marked with blue lines
and QRS complexes are in red

JET
• Difficult management: post-op
• several drugs may have to be tried in stepwise
fashion: amiodarone, propafenone, sotalol
Question
In atrial ectopic tachycardia (AET):
• 1. The etiology is automaticity
Question
• In atrial ectopic tachycardia (AET):
• 1. The etiology is automaticity
• 2. Warm-up and cool-down may be seen
Question
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In atrial ectopic tachycardia (AET):
1. The etiology is automaticity
2. Warm-up and cool-down may be seen
3. P wave is present
Question
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In atrial ectopic tachycardia (AET):
1. The etiology is automaticity
2. Warm-up and cool-down may be seen
3. P wave is present
4. Blocked Ps may be seen
Question
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In atrial ectopic tachycardia (AET):
1. The etiology is automaticity
2. Warm-up and cool-down may be seen
3. P wave is present
4. Blocked Ps may be seen
5. All of the above
Atrial flutter
Reentry:
• Intra-atrial reentry: note flutter waves
(“saw-tooth”), variable AV
conduction
Atrial flutter
Atrial flutter: management
• 1. Synchronized DC cardioversion: choice
treatment
• 2. Chronic flutter: risk of embolism >
anticoagulartion
• Digoxin, B-blockers, Ca blockers: delay AV
node conduction
• Other drugs used to maintain sinus rhythm:
procainamide, propafenene, amiodarone,
sotalol
Atrial flutter: management
Atrial flutter: unstable
1. Synchronized DC cardioversion: half doses
2. Calcium channel blockers:
Diltiazem: 0.25-0.35 mg/kg over 2-15
min (may repeat)
Drip: 0.5-0.15 mg/kg/h
3. Overdrive pacing: PM, esophageal lead
4. Other drugs:
procainamide, amiodarone, sotalol
Atrial flutter: management
• Neonatal flutter: digoxin for 1 yr after which
arrhythmia may not recur
Atrial fibrillation
• Uncommon
• Often associarted with atrial problem:
enlargement
• Seen in older children with atrial enlargement
or, rheumatic valve stenosis or surgery
Atrial fibrillation: management
• Rate control: Ca blockers
• No digoxin if there is WPW
• Acute:
Procainamide, amiodarone, DC cardioversion
Anticoagulation may be necesssary
Conclusions
SVT is the most common tachyarrhythmia in
children
The etiology is primarily reentry
In older children it is usually well tolerated
In infants it may be a life-threatening
emergency
GOOD LUCK !
Nodal rhythm
Note AV dissociation with “Ps” appearing from
time to time
Nodal bradycardia: HR 37bpm
3- year-old girl with hyperthyroidism (Pediatr 1997;
100.2.e11). Flutter 1:1 conduction. Note negative
flutter waves in V1-V3 and II, III, aVF
ATRIAL FLUTTER