Arryhthmia Flashcards
CH 435: SINUS TACHYCARDIA (ST)/SUPRAVENTRICULAR
TACHYCARDIA (SVT)/ VENTRICULAR TACHYCARDIA (VT)
Tachyarrhythmias – Rapid abnormal rhythms that originate from
the atria or the ventricles
- Can be tolerated without sx for a variable period of
time
Clinical manifestations
- Palpitations, lightheadedness, syncope
- Acute hemodynamic compromise (shock or cardiac
arrest) - Infants – poor feeding, irritability, rapid breathing
narrow QRS COMPLEX (≤0.09 seconds)
Sinus tachycardia
atrial flutter
SVT
Wide QRS COMPLEX (>0.09 seconds)
SVT with aberrant intraventricular conduction
Ventricular tachycardia
Sinus tachycardia
Sinus tachycardia – rate faster than UL for age (but usually
<200bpm); P waves present/N; variable RR, constant PR
Supraventricular tachycardia
SVT – MC pediatric tachycardia
- HR: 240 + 40 bpm
- No P wave, QRS usually N; HR not variable
- In some, there is an accessory pathway, an extra
connection linking the atria and ventricles (SA à AV à
ventricle à acc PW à inc HR)
- 2 separate mechanisms: 1) re-entry, 2) automaticity
- Causes: viral infection due to activation of SNS –
idiopathic SVT, WPW pre-excitation (10-20%),
Ebstein’s, single ventricle, congenital TGA more
susceptible, after cardiac surgery
- CM: CHF, irritability, poor feeding, hypoT, poor
perfusion
Ventricular tachycardia
VT – myocarditis, hypertrophic cardiomyopathy, dilated
cardiomyopathy, Brugada syndrome, Long QT syndrome
- CM: palpitation, dizziness, exercise intolerance, HF,
syncope, death
SINUS TACHYCARDIA VS SVT
SINUS TACHYCARDIA
gradual onset; signs of underlying cause can be identified such as fever, hypovolemia, anemia
HR(infants): <220/min
HR (children): <180/min
SUPRAVENTRICULAR TACHYCARDIA
acute onset or acute termination
Infant: symptoms of CHF
Child: sudden onste of palpitations
HR (Infants): ≥220/min
HR(children): ≥180/min
PEDIATRIC TACHYCARDIA WITH A PULSE and POOR PERFUSION ALGORITHM
P. 221
Pediatric tachycardia with a pulse and adequate perfusion
algorithm
P.221
Management of SVT
Mgt (SVT)
1. Older children – vagal stimulatory maneuvers
(unilateral carotid massage, gagging, P on eyeball),
headstand
- Infant: ice water bag on face x 10s
2. Acute Medications:
a. Propranolol
b. Adenosine 50 u/kg q1-2min rapid IV bolus
ffd by saline flush (inc by 50 ucg/min), usual
effective dose 100-150 ucg/kg, max dose
250 u/kg – DOC
- Long term Rx: B blockers, amiodarone, verapamil and
digoxin (discouraged if WPW), radiofrequency ablation
(permanent tx)
Management of Ventricular tachycardia
Mgt (VT)
1. Chronic tx – amiodarone, sotalol, phenytoin
What is SINUS BRADYCARDIA?
CH 435: SINUS BRADYCARDIA
Bradyarrhythmia – HR slow compared to N range for age, level of
activity, and clinical condition
Symptomatic bradycardia – HR slower than N with associated
hypotension, altered sensorium, or signs of shock
Sinus bradycardia – causes:
o Sinus node depolarization rate slower than
N for child’s age
o Often present in healthy children at rest
and in well-conditioned athletes
o May develop in response to hypoxia,
hypotension, acidosis, and drug effects
- Characteristics:
1. Regular rhythm with VR slower than N HR for age
2. P waves with constant morphology preceding every
QRS complex
3. P wave is positive in limb lead II
Classification of Bradycardia
Primary: Congenital or acquired heart conditions that result in slow spontaneous depolarization or slow conduction system
Ex: congenital abnormality of the heart (pacemaker or conduction system)
caardiomyopathy
myocarditis
surgical injury to the pacemaker or conduction system
Secondary:
non-cardiac conditions that alter the normal function of the heart
ex: hypoxia, acidosis, hypotension, hypothermia, effect of drugs
Management of bradycardia with a pulse and poor perfusion
p. 221
CH 435: HEART BLOCK (AV BLOCK)
CH 435: HEART BLOCK (AV BLOCK)
- Disturbance in conduction between normal sinus
impulse and eventual ventricular response
FIRST DEGREE AV BLOCK: prolonged PR interval for age and HR
PR Intervals usually >0.2 seconds
SECOND DEGREE AV BLOCK (MOBITZ TYPE 1) (Wenckebach):progressive prolongation of the PR interval (marked by horizontal arrows) until there is loss of AV conduction (OR A DROP BEAT)
THIRD DEGREE AV BLOCK:
no atrial depolarization is conducted through the AVnode
P and QRS are independent of each other
Clinincal manifestations of AV block
CM
1. Infant – slow HR, cannon waves in neck, gallops,
murmur, hydropic appearance secondary to HF (low CO), pallor, mottling, lethargy, more ill looking presentation
- Child – exercise intolerance, syncope, listlessness,
lethargy, hypotension, chest pain, dizziness
Types of AV Block
Types
1. First degree AV Block – abN delay in conduction usually
at AV node
- Mgt: no tx (unless sec to digitalis)
- Second degree AV Block
a. Mobitz Type 1 (Wenckebach phenomenon)
§ Delay in signal with each heart
beat further until beat is missed
completely
§ Sig: block is at the level of the AV
node
§ Does not progress to complete
heart block
§ Mgt: treat underlying cause
b. Mobitz Type 2
§ AV conduction is “all or none”
(normal vs completely blocked)
§ Block is at the level of bundle of
His
§ May progress to complete heart
block
§ Mgt: treat underlying cause - Third degree heart block
- Atrial and ventricular activities are entirely independent of each other
- None of SA signal reaches ventricles, ventricles
generate own impulse
- Characteristics: - P waves are regular. Q waves are regular (slower)
escape rhythm - Congenital CHB (VR 50-80) – QRS duration N
o pacemaker of ventricular complex is at level
higher than bifurcation of bundle of His - Acquired CHB (VR 40-50) – QRS duration
prolonged
o Pacemaker below level of bifurcation
o Cardiac surgery: MC cause
- CHF may develop in infancy if with CHD
- Px’s are usually asx’c, with N growth and devt
- Sudden onset of CHB may result in death
- Mgt:
o Atropine/ Isoproterenol – if sx’c
o Temporary transvenous ventricular
pacemaker
o No tx if asx’c
o Pacemaker tx if with:
§ Develops sx/CHF
§ Infant VR <50-55, or infant with
CHD VR<70
§ Wide QRS escape rhythm,
complex ventricular re-entry,
ventricular dysfunction
o Permanent pacemaker is surgically induced
HB persists >7d after surgery
