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High-Yield Facts

  • Dysrhythmias are classified according to rate, QRS width, and clinical stability.

  • Sinus bradycardia in the neonate always requires aggressive evaluation and treatment.

  • Infants with paroxysmal supraventricular tachycardia (PSVT) may present in a low output state with irritability, poor feeding, tachypnea, and diaphoresis.

  • The presence of an accessory pathway is the most common mechanism for PSVT in the child, but is difficult to appreciate during PSVT. Digoxin may precipitate ventricular tachycardia (VT) and is only used under the supervision of a pediatric cardiologist.

  • Atrial fibrillation or flutter associated with accessory pathway disease or hypertrophic cardiomyopathy (HC) puts a child at high risk for 1:1 conduction, ventricular tachycardia, and sudden death.

Disorders of rate and rhythm are fortunately rare in the pediatric population. The most common dysrhythmia is supraventricular tachycardia. Rhythm disturbances, such as sinus bradycardia, can be life-threatening, particularly in the neonate.

Dysrhythmias in children that are the result of cardiac lesions have a poorer prognosis than patients with a structurally normal heart. Noncardiac causes, such as hypoxia, electrolyte imbalance, toxins, and inflammatory disease, must be considered, as should cardioactive drugs, such as digoxin or over-the-counter cold remedies. Initial evaluation includes an electrocardiogram (ECG).

Age is an important consideration in the child presenting with a dysrhythmia. Age is also a factor in the clinical presentation of the dysrhythmia. The infant may present with poor feeding, tachypnea, irritability, or signs of a low output state. Caregivers often note that their baby is “not acting right.” The older child often presents with more specific symptoms, such as syncope from decreased cerebral blood flow, chest pain from decreased coronary blood flow, or palpitations. The ventricular rate in third-degree heart block may be adequate for the 2-month-old child but will not provide an adequate cardiac output for the child at age 12. Adolescents involved in competitive athletics with syncope, palpitations, or worrisome chest pain should be evaluated promptly. Normal ranges for heart rate and blood pressure are listed in Tables 42-1 and 42-2.

TABLE 42-1Expected Heart Rates According to Age1
TABLE 42-2Expected Systolic and Diastolic Blood Pressures According to Age

The initial emergency management of dysrhythmias is dependent on three factors: rate, QRS width, and clinical stability. Decisions should be ...

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