Cardiac Arrhythmias
Description Diagnostic criteria General and supportive measures Medicine Treatment Referral ICD-10 code: I49.9 DESCRIPTION A heart rate that is either abnormally slow or fast for age or irregular. Normal heart rate/minute for age: Newborn 100–160 < 1 year 110–160 1–2 years 100–150 2–5 years 95–140 5–12 years 80–120 > 12 years 60–100 DIAGNOSTIC CRITERIA Clinical Presenting features may
Description
Diagnostic criteria
General and supportive measures
Medicine Treatment
Referral
ICD-10 code: I49.9
DESCRIPTION
A heart rate that is either abnormally slow or fast for age or irregular.
Normal heart rate/minute for age:
| Newborn | 100–160 |
| < 1 year | 110–160 |
| 1–2 years | 100–150 |
| 2–5 years | 95–140 |
| 5–12 years | 80–120 |
| > 12 years | 60–100 |
DIAGNOSTIC CRITERIA
Clinical
- Presenting features may vary with the age of the patient:
- infants:
- colour changes (pale, mottled),
- irregular pulse,
- irritability,
- tachycardia,
- feeding difficulties,
- bradycardia,
- sweating,
- signs of cardiac failure,
- tachypnoeic/apnoeic spells.
- children:
- dizziness,
- tachycardia,
- palpitations,
- bradycardia,
- fatigue,
- syncope,
- chest pain,
- signs of cardiac failure.
- infants:
Investigations
- ECG is essential for diagnosis, preferably a 12- lead ECG.
- Monitors are inadequate to diagnose most arrhythmias.
- A standard ECG is recorded at 25 mm/second. Each small block on the ECG paper is 1 mm x 1 mm and represents 40 milliseconds and each large block 5 mm x 5 mm and represents 200 milliseconds. A length of 300 large blocks represents 1 minute and the heart rate can be estimated from the ECG strip by dividing 300 by the number of large blocks between sequential R waves provided that there is not substantial variability in the RR interval lengths. The ECG tracings below show only the large (5 mm) blocks.
TACHYARRHYTHMIA
Sinus tachycardia
Click on image to enlarge
ECG Criteria
Rate: > upper limit for age
P wave: present and normal
Rhythm: regular
QRS: normal
Supraventricular tachycardia
Click on image to enlarge
ECG Criteria
Rate: usually > 200 beats per minute
P wave: abnormal
Rhythm: regular
QRS: normal
Ventricular tachycardia
Click on image to enlarge
ECG Criteria
Rate: generally 100–220 beats per minute
P wave: mostly not seen
Rhythm: generally regular
QRS: abnormal, width of QRS > 120 milliseconds
BRADYARRHYTHMIA
- Important causes of bradycardia:
- Hypoxia
- Drug ingestion.
- Congenital heart block.
- Excessive vagal stimulation.
- Hypothyroidism
- Head injury.
Sinus bradycardia
Click on image to enlarge
ECG Criteria
Rate: < lower limit for age
P wave: present, all look the same
Rhythm: regular
QRS: normal, 80–120 milliseconds
Heart block (Complete)
Click on image to enlarge
ECG Criteria
Rate: low, usually < 60 beats per minute
P wave: independent P waves and QRS complexes with no relationship between the two (AV dissociation)
Rhythm: regular
QRS complex: can be normal or wide, depending on escape rhythm
GENERAL AND SUPPORTIVE MEASURES
- Sinus tachycardia usually requires management of the underlying condition.
- Apply ABC of resuscitation if needed.
- Admit to high care or intensive care unit if indicated.
- Monitor:
- ECG,
- oxygen saturation,
- blood pressure,
- haemoglobin,
- heart rate,
- acid–base status,
- respiratory rate,
- blood gases.
- Maintain adequate nutrition and hydration.
- Treat pyrexia.
MEDICINE TREATMENT
Tachydysrhythmia
Emergency treatment.
Narrow complex tachycardia
Commonly due to supraventricular tachycardia.
Stable patient:
Attempt vagal stimulation:
- Place ice bag on face, or
- Infants: immerse face in ice-cold water for a few seconds.
- Older children: try a valsalva manoeuvre.
- Eye-ball pressure and carotid massage is contraindicated in children.
- In consultation with a paediatric specialist: Adenosine, IV, 0.1 mg/kg rapid IV push via a large bore cannula (within seconds). For infants, start with 0.2 mg/kg1 .
- Follow immediately with a rapid flush of at least 5 mL sodium chloride 0.9%.
- Increase dose in 0.1 mg/kg increments every 2 minutes until return of sinus rhythm. Follow each dose with a rapid flush of sodium chloride 0.9%.
- Maximum dose: 0.5 mg/kg. Do not exceed 12 mg in total.
- Because adenosine is rapidly metabolised, inject adenosine into an intravenous cannula capable of supporting rapid infusion and preferably located as centrally as possible (i.e. cubital rather than hand or foot). Follow immediately, with a rapid flush of a fluid bolus. It is helpful to have both the syringe with adenosine and the fluid bolus connected to the giving set. The line between the syringes and the patient should be as short as possible.
Unstable patient – heart failure / shocked:
- DC synchronised cardioversion at 1 J/kg, and then 2 J/kg.
- If possible, empty the stomach before cardioversion is attempted. Resuscitation facilities must be available.
- Ketamine for sedation, if necessary. See: Procedure Sedation and Analgesia.
Broad complex tachycardia
Commonly due to ventricular tachycardia.
Causes include electrolyte disturbances and drug ingestion.
Stable patient (rare):
- Send ECG immediately to paediatric cardiologist.
- AVOID giving adenosine to patients with broad complex tachycardia unless the rhythm is regular with a monomorphic QRS complex.
Medicines that may be recommended by a paediatric cardiologist include:
- Magnesium sulphate, IV, 25–50 mg/kg over a few minutes for torsade de pointes.
- Amiodarone, IV, 5 mg/kg over 20 minutes.
Unstable patient – heart failure/shock:
- Pulseless – treat as ventricular fibrillation. See: Cardiorespiratory arrest.
- DC synchronised cardioversion at 1 J/kg, and then 2 J/kg.
- If synchronised cardioversion fails, use asynchronised shocks.
- Resuscitation facilities must be available.
- Ketamine for sedation, if necessary. See: Procedure Sedation and Analgesia.
Monitor and correct electrolytes and acid-base status on blood gases. Consider underlying causes.
If DC cardioversion fails:
- Amiodarone, IV, 5 mg/kg slowly over 20 minutes.
AND
- Continue with DC cardioversion.
Bradyarrhythmia
Try and correct underlying causes.
Stable patient:
Observe
Bradyarrhythmia due to vagal stimulation:
- Atropine, IV/IO, 0.02 mg/kg. Maximum single dose 0.5 mg.
- If no response, repeat in 5 minutes.
Unstable patient:
Treat as impending arrest:
- Adrenaline (epinephrine), IV/IO, 0.01 mg/kg.
- Repeat if necessary, conferring with referral institution.
If no sustained response, consider:
- Adrenaline (epinephrine), IV infusion, 0.05–2 μg/kg/minute
REFERRAL
- All children with tachyarrhythmias after acute treatment, excluding sinus tachycardia due to other causes.
- Bradycardia unresponsive to medical treatment, or heart block.
Standard Treatment Guidelines And Essential Medicines List For South Africa, Hospital Level, Paediatrics, 2023 Edition
Chapter 4: Cardiovascular System , 4.1 Cardiac Arrhythmias