Pediatric emergency medicine trisk 382

TABLE 77.3
LIFE-THREATENING CAUSES OF TACHYCARDIA
Sinus tachycardia
Anaphylaxis
Hypoxia
Hypoglycemia
Sepsis
Shock
Pheochromocytoma
Poisoning (see Table 63.4 )
Myocarditis
Pericardial effusion with tamponade
Cardiac
Supraventricular tachycardia
Ventricular tachyarrhythmias
Atrial flutter

EVALUATION AND DECISION
The child with tachycardia requires rapid assessment for the presence of hypoxia,
hypoglycemia, an existing life-threatening arrhythmia, or shock ( Fig. 77.1 ).
Respiratory distress with cyanosis or low pulse oximetry (less than 90%)
demands immediate provision of supplemental oxygen and further management
of airway and breathing (see Chapters 8 Airway and 99 Pulmonary Emergencies
). Hypoglycemia typically presents with tremor, anxiety/irritability, diaphoresis,
and/or altered mental status and can be confirmed by measuring rapid blood
glucose level. If an arrhythmia is suggested by an extremely rapid heart rate or a
concerning tracing on the bedside cardiac monitor, a 12-lead electrocardiogram
(EKG) and rhythm strip are necessary to confirm this impression and to guide
further treatment (see Chapter 86 Cardiac Emergencies ). Children with
congenital heart disease or a family history of sudden death are at increased risk
for a life-threatening tachyarrhythmia. Consultation with a pediatric cardiologist

and/or emergent echocardiography is warranted. In patients with shock,
additional history and physical findings may help guide the clinician. Although
the etiology may not be initially apparent, rapid treatment is imperative (see
Chapter 10 Shock ).


Children with fever and sinus tachycardia typically have a self-limited febrile
illness. If the tachycardia is to be attributed to the presence of fever, then it would
be prudent to at the least reassess the heart rate after defervescence. If the
tachycardia persists then one must consider other etiologies such as sepsis,
dehydration, or cardiac pathology. Fever is also present in patients with cardiac
pathologies such as myocarditis, pericarditis/pericardial effusion, Kawasaki
syndrome, and acute rheumatic fever. Myocarditis describes inflammation of the
muscle wall of the heart. Clinical features of this disease are fever, tachycardia
out of proportion to the activity or degree of fever, pallor, cyanosis, respiratory
distress secondary to pulmonary edema, muffled heart sounds with gallop, and
hepatomegaly caused by passive congestion of the liver (see Chapter 86 Cardiac
Emergencies ). A child with tachycardia and clinical findings suggestive of
myocarditis requires emergent supportive care (see Chapter 7 A General
Approach to the Ill or Injured Child ), infectious disease/cardiology consultations,
echocardiography, and admission to a unit capable of intensive monitoring and
rapid treatment of cardiac arrhythmias and hemodynamic instability.


FIGURE 77.1 A diagnostic approach to tachycardia. a Altered mental status, diaphoresis,
hypertension. b See Chapter 10 Shock . HR, heart rate; EKG, electrocardiogram; SVT,
supraventricular tachycardia; ARF, acute rheumatic fever.

Pericardial effusion may occur after blunt chest trauma, viral infection, or as a
component of inflammatory diseases such as systemic lupus erythematosus.

Small effusions may be detected as a friction rub. Large effusions often cause
cardiogenic shock and may lead to muffling of heart sounds and EKG changes,
such as low-voltage or T-wave flattening with “strain” pattern in leads V1
through V6, but are nonspecific. Pericardial effusions are best identified using
ultrasound. Patients with evidence of significant circulatory impairment should


undergo a pericardial drainage procedure (e.g., placement of a pericardial catheter
percutaneously under ultrasound guidance and/or pericardial window procedure).
Acute rheumatic fever follows pharyngeal streptococcal infection and is an
inflammatory disease that targets the heart, vessels, joints, skin, and central
nervous system (CNS). Diagnosis and management of acute rheumatic fever are
discussed separately (see Chapter 86 Cardiac Emergencies ). Clinical criteria for
Kawasaki disease consist of prolonged high fever, conjunctivitis with perilimbic
sparing, “strawberry tongue,” painful swelling of the hands and feet, rash, and
lymphadenopathy. Early recognition and treatment of Kawasaki disease with
intravenous γ-globulin is necessary to prevent the development of coronary artery
aneurysms with potential for myocardial ischemia (see Chapter 101
Rheumatologic Emergencies ).
Patients with thyroid storm may have marked sinus tachycardia, fever, goiter,
and CNS stimulation (agitation, delirium, psychosis, seizures) accompanied by
congestive heart failure (see Chapter 89 Endocrine Emergencies ). Trauma,
thyroid infection, thyroid surgery, and acute iodine load are frequent precipitants.
Rapid recognition and institution of therapy to treat adrenergic symptoms (βadrenergic blockers), block hormone synthesis (methimazole), prevent peripheral
conversion of T4 to T3 (iodinated radiocontrast agents), and prevent thyroid
hormone release (iodine) are necessary to prevent mortality.
Crying, pain, or anxiety is the most frequent cause of sinus tachycardia in
afebrile children. Drug ingestion, poisoning, and anemia are important additional
considerations (see Table 63.4 ). Rarely, sinus tachycardia may herald the
presence of hyperthyroidism or pheochromocytoma, a catecholamine-secreting

tumor that causes extreme hypertension, diaphoresis, and flushing (see Chapter
89 Endocrine Emergencies ).
Suggested Readings and Key References
American Heart Association. Pediatric Advanced Life Support Provider Manual .
Dallas, TX: American Heart Association; 2016.
Fleming S, Thompson M, Stevens R, et al. Normal ranges of heart rate and
respiratory rate and respiratory rate in children from birth to 18 years of age: a
systematic review of observational studies. Lancet 2011;377:1011–1018.
Fuchs S, Yamamoto L, eds. APLS: The Pediatric Emergency Medicine Resource .
5th ed. Burlington, MA: Jones & Bartlett Learning; 2012.
Mazor S, Mazor R. Approach to the child with tachycardia. UpToDate . Available
online at www.uptodate.com . Accessed April 18, 2019.