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 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 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 ... 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... 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