Arryhthmia

Question 1

CH 435: SINUS TACHYCARDIA (ST)/SUPRAVENTRICULAR
TACHYCARDIA (SVT)/ VENTRICULAR TACHYCARDIA (VT)

Answer 1

Tachyarrhythmias – Rapid abnormal rhythms that originate from
the atria or the ventricles
- Can be tolerated without sx for a variable period of
time

Question 2

Clinical manifestations

Answer 2

1. Palpitations, lightheadedness, syncope
2. Acute hemodynamic compromise (shock or cardiac
   arrest)
3. Infants – poor feeding, irritability, rapid breathing

Question 3

narrow QRS COMPLEX (≤0.09 seconds)

Answer 3

Sinus tachycardia
atrial flutter
SVT

Question 4

Wide QRS COMPLEX (>0.09 seconds)

Answer 4

SVT with aberrant intraventricular conduction
Ventricular tachycardia

Question 5

Sinus tachycardia

Answer 5

Sinus tachycardia – rate faster than UL for age (but usually
<200bpm); P waves present/N; variable RR, constant PR

Question 6

Supraventricular tachycardia

Answer 6

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

Question 7

Ventricular tachycardia

Answer 7

VT – myocarditis, hypertrophic cardiomyopathy, dilated
cardiomyopathy, Brugada syndrome, Long QT syndrome
- CM: palpitation, dizziness, exercise intolerance, HF,
syncope, death

Question 8

SINUS TACHYCARDIA VS SVT

Answer 8

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

Question 9

PEDIATRIC TACHYCARDIA WITH A PULSE and POOR PERFUSION ALGORITHM

Answer 9

P. 221

Question 10

Pediatric tachycardia with a pulse and adequate perfusion
algorithm

Answer 10

P.221

Question 11

Management of SVT

Answer 11

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

3. Long term Rx: B blockers, amiodarone, verapamil and
   digoxin (discouraged if WPW), radiofrequency ablation
   (permanent tx)

Question 12

Management of Ventricular tachycardia

Answer 12

Mgt (VT)
1. Chronic tx – amiodarone, sotalol, phenytoin

Question 13

What is SINUS BRADYCARDIA?

Answer 13

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

Question 14

Classification of Bradycardia

Answer 14

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

Question 15

Management of bradycardia with a pulse and poor perfusion

Answer 15

p. 221

Question 16

CH 435: HEART BLOCK (AV BLOCK)

Answer 16

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

Question 17

Clinincal manifestations of AV block

Answer 17

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

2. Child – exercise intolerance, syncope, listlessness,
   lethargy, hypotension, chest pain, dizziness

Question 18

Types of AV Block

Answer 18

Types
1. First degree AV Block – abN delay in conduction usually
at AV node
- Mgt: no tx (unless sec to digitalis)

2. 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
3. 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:
4. P waves are regular. Q waves are regular (slower)
   escape rhythm
5. Congenital CHB (VR 50-80) – QRS duration N
   o pacemaker of ventricular complex is at level
   higher than bifurcation of bundle of His
6. 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