Management of Tachycardia in an 11-Year-Old
Begin with a 12-lead ECG to document the rhythm and heart rate, then systematically assess for underlying causes including fever, dehydration, anemia, and hyperthyroidism before attributing symptoms to a primary arrhythmia. 1
Initial Assessment and Stabilization
Determine hemodynamic stability first – this dictates your entire management pathway. 2, 1
- If the patient shows signs of hemodynamic instability (altered mental status, chest discomfort, hypotension, shock, acute heart failure), proceed immediately to synchronized cardioversion. 2
- Do not delay cardioversion for IV access if the patient is extremely unstable. 2
- If conscious, provide sedation before cardioversion when possible. 2
For hemodynamically stable patients, obtain supplementary oxygen if needed, attach a cardiac monitor, evaluate blood pressure, and establish IV access. 2
Diagnostic Workup
Obtain a 12-lead ECG immediately – this is essential before any rhythm-terminating intervention. 1, 2
Look specifically for:
- Pre-excitation (delta waves) suggesting Wolff-Parkinson-White syndrome – this requires immediate cardiology referral. 1
- QRS duration: Wide complex (>120 ms) versus narrow complex tachycardia. 2
- P-wave morphology and relationship to QRS to distinguish between sinus tachycardia, SVT, atrial flutter, or other mechanisms. 2
- Prolonged QT interval or Brugada pattern – these require urgent cardiology consultation. 1
Order an echocardiogram to exclude structural heart disease including hypertrophic cardiomyopathy, dilated cardiomyopathy, valvular abnormalities, and coronary artery anomalies. 1, 3
Determine the Mechanism
Sinus Tachycardia (Most Common)
The upper limit of physiologic sinus tachycardia for an 11-year-old is approximately 209 bpm (220 minus age). 2, 1
- Sinus tachycardia is almost always secondary to an underlying condition – fever, dehydration, anemia, hyperthyroidism, anxiety, pain, or medications. 2, 1
- Do not treat the heart rate itself – identify and treat the underlying cause. 2, 1
- With rates <150 bpm in the absence of ventricular dysfunction, the tachycardia is more likely secondary to the underlying condition rather than the cause of instability. 2
- Critical pitfall: When cardiac function is poor, cardiac output can be dependent on a rapid heart rate; "normalizing" the heart rate in compensatory tachycardia can be detrimental. 2
Supraventricular Tachycardia (SVT)
SVT in children typically presents with heart rates >180 bpm in children and >220 bpm in adolescents. 4
For stable patients with regular narrow-complex SVT:
- Attempt vagal maneuvers first (Valsalva maneuver, diving reflex stimulation for younger children, or unilateral carotid sinus massage). 5, 6, 4
- If vagal maneuvers fail, administer adenosine as a rapid IV push under continuous cardiac monitoring. 5, 6, 4
- Adenosine may be considered while preparing for synchronized cardioversion in stable patients with suspected reentrant SVT. 2
For unstable patients with SVT:
- Proceed directly to synchronized cardioversion starting at 50-100 J for SVT. 2
- If the initial shock fails, increase the dose in a stepwise fashion. 2
Mandatory Cardiology Referral Criteria
Immediate cardiology referral is required for: 1
- Pre-excitation (WPW syndrome) on ECG
- Syncope during tachycardia or with exercise
- Wide complex tachycardia of unknown origin
- Documented sustained SVT
Critical Pitfalls to Avoid
Persistent tachycardia over weeks to months can cause tachycardia-mediated cardiomyopathy, which is reversible but requires careful long-term follow-up even after recovery. 1
Never administer IV verapamil to infants or young children – it can cause severe hemodynamic collapse. 7
Do not assume all tachycardia is benign sinus tachycardia – always obtain a 12-lead ECG to document the rhythm and exclude dangerous arrhythmias. 1, 2
Syncope with aortic stenosis is an ominous sign requiring urgent intervention in pediatric patients. 1