Click for pdf: Tachycardia
Tachycardia is an abnormally rapid heart rate. In adults, this is usually defined as >100 beats per minute (bpm). In pediatrics, the normal heart rate varies with age (see Table 1). Therefore, in children, the definition of tachycardia is age dependent. Presentation varies with underlying cause, but most often the symptoms are vague and non-specific, such as “fussiness” or “difficulty feeding”.
Basic Anatomy and Physiology
Normal pediatric ranges for heart rate can be found in Table 1. The heart receives both sympathetic (sympathetic ganglion, increases heart rate) and parasympathetic (vagus nerve, decreases heart rate) innervation. Tachycardia may result from physiologic processes that alter the sympathetic/parasympathetic tone, resulting in a sinus tachycardia. Alternatively, tachycardia may be the result of an arrhythmia: atrial fibrillation; atrial flutter; supraventricular tachycardia; or ventricular tachycardia. There are many medications that can cause tachycardia, either by leading to the release of catecholamines, or by inducing an arrhythmia.
Questions to Ask
- Does the child have a history of tachycardia, or a known cardiac condition?
- What is the onset and duration of the child’s current illness (if present)?
- Does the child have other symptoms, such as:
- Chest pain
- Shortness of breath
- Colour change
- Neurologic symptoms (e.g., change in level of consciousness)
- Does the child take any medications?
- Does the child have any allergies?
- Is there a family history of cardiac problems?
- Does the tachycardia occur at certain times (e.g., with activity, following meals, under stress)?
- Does the child feel hot/have a fever?
- Has the child been vomiting or having diarrhea?
- Has the child been drinking?
- What is their urine output?
- Sinus Tachycardia secondary to dehydration/hypovolemia (most common), fever, hypoxia, anemia, shock, MI, pulmonary edema, hyperthyroidism, hypocalcemia, or medications
- Supraventricular Tachycardia (AV re-entry, junctional, or atrial ectopic)
- Ventricular Tachycardia
- Atrial flutter
- Atrial fibrillation
*See Table 3
- Focus on general appearance, hydration status, vital signs, respiratory exam (retractions, increased work of breathing, crackles, wheezing), cardiac exam (dyspnea, liver size, peripheral perfusion, cyanosis, rate/rhythm, murmurs), level of consciousness.
- Electrolytes, CBC, glucose, Mg, Ca. Consider toxicology screen, thyroid function studies, blood gas.
- Consider CXR, cardiac echo.
- 12 lead ECG
Table 1: Pediatrics HR ranges
|Age||Normal Range (Average)
|< 1 day||93-154 (123)|
|1-2 days||91-159 (123)|
|3-6 days||91-166 (129)|
|1-3 weeks||107-182 (148)|
|1-2 months||121-179 (149)|
|3-5 months||106-186 (141)|
|6-11 months||109-169 (134)|
|1-2 years||89-151 (119)|
|3-4 years||73-137 (108)|
|5-7 years||65-133 (100)|
|8-11 years||62-130 (91)|
|12-15 years||80-119 (85)|
|> 16 years||60-100|
Table 2: Tachycardia inducing medications
|Induce increase in catecholamine release||Induce Ventricular Tachycardia|
Table 3: Differential diagnosis
|Sinus||Supra- Ventricular Tachycardia (reentry)||Atrial Flutter||Atrial Ectopic Tachycardia||Junctional Ectopic Tachycardia||Ventricular Tachycardia|
|50% Wolff-Parkinson-White syndrome25% Atrio-ventricular nodal reentrant tachycardiaEbstein’s anomaly||90% have dilated atriaMyocarditisDigoxin toxicity||Usually normal heart||Post cardiac surgery||>70% have abnormal heartPost cardiac surgeryMyocarditisLong QT syndrome
|Rate||Usually <200/min||Infants: < 300/minChildren: <240/min||Atrial rate 250-400/min2:1, 3:1, or 4:1 AV block||> 200/min||Atrial rate < VentricularUp to 300/min||Usually <250/min|
|P wave||Normal||May be buried in QRS60% has retro-grade P wave||Regular flutter waves||Abnormal but constant||Retrograde P waves||A-V dissociationSometimes retrograde P|
|QRS||Normal||Normal or aberrant||Normal||Normal||Normal||Wide|
|Treatment||Treat underlying cause||PALS (pediatric advanced life support) algorithm||DigoxinAnti-arrythmicsDC cardioversion||Anti-arrythmics||CoolingNormalize pH and volumeAnti-arrythmics||PALS (pediatric advanced life support) algorithm|
Behrman RE, Kliegman RM. Nelson essentials of pediatrics. Philadelphia : W.B. Saunders, c2002
Cheng A, Williams BA, Sivaragan BV. The HSC Handbook of Pediatrics. Toronto : Elsevier Canada, c2003
Doniger SJ, Sharieff GQ. Pediatric Dysrhythmias. Pediatr Clin N Am 53 (2006) 85– 105
Farah M. Pediatrics, Tachycardia. http://www.emedicine.com/EMERG/topic408.htm
Written by: Justin Haba
Edited by: Anne Marie Jekyll