arrhythmias – clinical features

Arrhythmias: Bland & the Nasty

Approach to Childhood Arrhythmias

• Tachyarrhythmias– Classification– Diagnostic approach– Immediate treatment strategies

Long term management of tachyarrhythmias

Bradyarrhythmias


Classification of tachycardia

• conventional SVT / VT

• electrophysiological re-entry / automatic• appearance normal QRS / wide QRS

• age infancy / childhood• behaviour paroxysmal / incessant

• structural normal / post-op

• significanceBland / nasty

• substrate e.g. accessory connection

• Mechanism e.g. orthodromic AV re-entry

Non invasive diagnosis of tachycardia


Typical responses!

Panic is an unnecessary and inappropriate response because most childhood arrhythmias are associated

with stable hemodynamics


Arrhythmia Management: Basic Rule

• Diagnosis before treatment • A variety of incorrect practices in

management of arrhythmias result from a failure to respect this simple rule

Unless it is an emergency resist the urge to treat the arrhythmia before being sure what it is!


Diagnostic Approach for Tachyarrhythmias

Traditional Classification

Narrow QRS

Usually stable hemodynamics

Supraventricular

Broad QRS

Often unstable hemodynamics

Ventricular /supraventricular


1 : 1 A V B

r e g u l a r i r r e g u l a r

n o r m a l Q R S

L B B B R B B B n e i t h e r

r e g u l a r i r r e g u l a r

w i d e Q R S

t a c h y c a r d i a

Diagnosis of tachycardia

Classification of tachycardia



essential information

• history - age of onset, symptoms, etc• ECG in tachycardia• ECG in sinus rhythm

• ECG with adenosine administration


Irregular heart beatInappropriate heart rate for the situationUnexplained CHFDiseases associated with arrhythmiasSyncope/palpitationsFamily history

Arrhythmias – clinical features


Arrhythmias: The First Step

• Connect the child to an ECG machine

• Get a 12 lead ECG

• If the child is uncooperative, at least get the limb leads


The Monitor Can Mislead

• Single non-standard lead• P waves are not often clearly seen

• Interpretation of QRS morphology• Regular vs. Irregular rhythm• Difficult to document response to

intervention


ECG analysis - normal QRS

• are the QRS complexes regular?• are P waves seen?• what is the AV or VA relationship?• where is the P wave in the RR interval?



Narrow QRS Tachycardia

Irregular• Atrial fibrillation• Multifocal or chaotic

atrial tachycardia• Flutter with varying

conduction

Regular• Sinus tachycardia• Atrial Flutter• AV nodal re-entrant

tachycardia• Tachycardias based

on bypass tracts

•Ectopic atrial tachycardia•Junctional ectopic tachycardia


Irregular Narrow QRS Tachycardia


Fast AF in patient with ASD


Irregular Narrow QRS Tachycardia

MAT

Ectopic atrial tachycardia

A Flutter with varying conduction


P wave morphology

I

II

III


12 Lead ECG: P-QRS Relationship

A-V dissociation: JET


Sinus Tachycardia


Sinus Tachycardia: A Cause Can Almost Always be Found

• Anxiety

• Fever

• Hypovolemia

• Hyperthyroidism

• Bronchodilators


Sinus Tachycardia: In the ICU

• “Light” sedation

• Inotropes and chronotropes

• Low output

• Fever (rectal temp)

• Hypovolemia


Sinus Tachycardia

• Rates can be as high as 240/min

• Subtle variations in rate

• Treating cause brings down the rate

• When in doubt: 12 lead ECG

• If doubts persist: adenosine


Narrow QRS Tachycardia: P Waves are not always Seen…..



Recording response to adenosine

•Ultra short acting

•Blocks conduction across the AV node

•Terminates tachyarrhythmias where AV node is a part of the circuit

•Temporarily slows heart rates if circuit above AV node


Administering Adenosine

Adenosine 50-200 mcg/kg, fast push

Saline bolus, fast push

Reliable proximal IV line

10 cm extn.


Stable Narrow QRS tachycardiaAdenosine 140 mcg/kg bolus

Sudden termination

AVNRTAVRT

Slow and unmask

Flutter,ectopic atrial

tachy

No effect

Sinus tachy,Junctional ectopic

tachycardia


AV nodal re-entrant tachycardia: Sudden termination with adenosine

Response to Adenosine

Tachycardia Sinus



Tachyarrhythmia after Senning + Rastelli (LTGA, VSD, PS)

Surface

Atrial

Atrial

Abrupt restoration to Sinus Rhythm after adenosine



Narrow QRS tachycardia @ 200/min

Unmasking of atrial activity (Flutter waves)


Alternatives to Adenosine

• Ice bag on face; effects similar to adenosine• Older children and teens:

– Carotid sinus massage, supine valsalva

– Verapamil 0.1 mg / kg slow (only for narrow QRS tachycardias

• Cardioversion: Synchronized DC shock - 0.5 – 1 J/kg. First line for unstable narrow QRS tachycardia


Response to DC Shock

Responders: all re-entrant arrhythmias

A Flutter, AVRT, AVNRT, reentrant VT

Non-responders: all tachycardias based on automatic foci

JET, EAT, Sinus tachycardia, MAT


After the Event: ECG in Sinus Rhythm


Failure of the tachycardia to terminate after adenosine

Cardioversion

Ectopic atrial Tachycardia

Flutter

Sinus Tachycardia

Beta BlockadeDigoxin

Amiodarone

Digoxin, Betablockade

Rarely Amiodarone

Treat the Cause


Tachycardiomyopathy

• Certain incessant tachycardia in children can present clinically with heart failure and LV dysfunction like “myocarditis or DCM”

• Permanent Junctional Re-entrant tachycardia: RF ablation

• Ectopic atrial tachycardia: Antiarrhythmic medications / RF ablation


ECG analysis - wide QRS

• what is the QRS morphology in sinus rhythm?• is the QRS pattern LBBB, RBBB, pre-excited,

other?• are the QRS complexes regular?• are P waves seen?• what is the AV / VA relationship?



TORSADES DE POINTES


Wide QRS tachycardia

Stable Unstable

DC shockIf 1:1 P-QRS relation, try adenosine

If AV dissociation, IV Lignocaine 1 mg/kg or IV amiodarone 5 mg/kgIf no response, DC shock CPR


Unstable Wide QRS Tacharrhythmia

• VT• Synchronized DC

shock 0.5-2 J/kg

• VF• Unsynchronized

DC shock 2-4 J/kg


ECG After the Event……..

Long QT syndrome

arrhythmias – clinical features

Documents

r i r r e g u

tachycardia ecg

d e q r st

management of arrhythmias

rn o r

qrs complexes regular

v br e g u

nastyecg analysis normal