AACN CCRN (Pediatric)Free Critical-Care Registered Nurse (Pediatric) practice test

Correct answer: D. Untreated group A beta-hemolytic streptococcal pharyngitis

Acute rheumatic fever (ARF) develops as an abnormal immune response following untreated or inadequately treated group A beta-hemolytic streptococcal (GAS) pharyngitis. It predominantly affects children between 6 and 15 years of age and can involve the heart (carditis), joints (polyarthritis), skin, and central nervous system (Sydenham's chorea). The combination of fever, migratory joint pain, and a new murmur following a recent untreated sore throat is the hallmark presentation of ARF. Mycoplasma pneumoniae causes atypical pneumonia and is not implicated in ARF. Epstein-Barr virus produces pharyngitis and lymphadenopathy but does not trigger ARF. Influenza A causes respiratory illness but has no established connection to post-infectious rheumatic disease.

Correct answer: C. Valvular aortic stenosis (AS)

Valvular aortic stenosis best explains the combination of exertional symptoms, collapse, and a harsh systolic murmur at the right second intercostal space. Narrowing of the aortic valve obstructs left ventricular outflow, elevates LV pressure, and causes compensatory hypertrophy. The condition is often silent until adolescence, when exercise-related demands unmask dyspnea, angina, or syncope. VSD produces a holosystolic murmur at the left lower sternal border and typically causes heart failure in infancy rather than isolated exertional syncope. PDA generates a continuous machine-like murmur at the left infraclavicular area. HCM can also cause exertional syncope but its murmur is loudest at the left lower sternal border and augments with the Valsalva maneuver, making the right upper sternal border location more consistent with AS.

Correct answer: B. Respiratory distress

Digoxin is prescribed for mild-to-moderate heart failure, rate control in atrial arrhythmias, and fetal tachycardia management. Its toxic manifestations are essentially exaggerations of its therapeutic actions, primarily affecting the gastrointestinal and cardiovascular systems: bradycardia, dysrhythmias, hypotension, nausea, and vomiting are all classic toxic effects. The specific antidote is digoxin immune Fab (Digibind). Caregivers should verify the heart rate exceeds 60 bpm before each dose and monitor for toxicity signs such as poor appetite, nausea, vomiting, and visual disturbances. Respiratory distress is not a recognized clinical manifestation of digoxin toxicity and would suggest a different etiology.

Correct answer: A. Severe bradycardia

Digoxin's therapeutic mechanism amplifies its toxic profile; at supratherapeutic levels, the drug causes exaggerated cardiovascular and gastrointestinal effects. Severe bradycardia, dysrhythmias, and hypotension are hallmark cardiovascular manifestations of toxicity, while nausea, vomiting, and loss of appetite represent GI involvement. Digibind (digoxin immune Fab) is the antidote. Prior to each dose, heart rate should be confirmed above 60 bpm, and serum electrolytes and drug levels should be monitored regularly. Toxicity may occur even when serum levels fall within the therapeutic trough range of 0.5 to 2 ng/mL.

Correct answer: B. Rhythm originating from the sinoatrial (SA) node

On ECG, sinus tachycardia displays a normal upright P wave before every QRS complex with a 1:1 P-to-QRS ratio, normal PR interval, normal QRS morphology, regular rhythm, and an elevated rate that may reach 250 bpm in neonates (overlapping with supraventricular tachycardia). The pacemaker of origin is the SA node. Sinus tachycardia is almost universally secondary to an underlying condition; addressing the cause resolves the tachycardia. An inverted P wave suggests an ectopic atrial focus not arising from the SA node. Prolonged pauses and irregular rhythm are not features of sinus tachycardia.

Correct answer: C. Coarctation of the aorta

Aortic coarctation is a congenital narrowing of the descending aorta that elevates proximal pressure and reduces distal pressure, producing a characteristic blood pressure gradient between upper and lower extremities along with upper-body hypertension. It represents approximately 8-10% of congenital heart disease cases and is more prevalent in males. Associated anomalies include PDA, VSD, aortic stenosis, bicuspid aortic valve, and DiGeorge syndrome. The murmur is a nonspecific short systolic ejection murmur heard at the left sternal border. TOF presents with cyanosis, irritability, and potential cardiac arrest. VSD leads to pulmonary hypertension and fatigue from increased pulmonary flow. Tricuspid atresia causes congestive heart failure and requires an obligatory right-to-left atrial shunt for survival.

Correct answer: C. Audible expiratory wheezes on auscultation

Propranolol is a nonselective beta-blocker used for arrhythmias, tachyarrhythmias, hypertension, and myocardial infarction management by blunting sympathetic stimulation of the heart. Audible expiratory wheezes signal bronchospasm, a significant and potentially dangerous adverse effect of nonselective beta-blockade, particularly in patients with underlying reactive airway disease. Other adverse effects include laryngospasm, bone marrow suppression, bradycardia, and hypotension. Changes in taste and blurred vision are not recognized side effects. Respiratory depression, while serious, is distinct from bronchospasm and is not a primary concern with propranolol.

Correct answer: C. Tachypnea and tachycardia

Cardiomyopathy involves myocardial dysfunction with associated mechanical and electrical abnormalities, resulting in ventricular dilation or hypertrophy. Its clinical presentation reflects progressive degrees of heart failure. Tachycardia, tachypnea, increased work of breathing, diaphoresis, poor appetite, feeding intolerance, decreased weight gain, abdominal discomfort, and reduced exercise capacity are characteristic findings. A continuous machine-like murmur is the signature of a patent ductus arteriosus, not cardiomyopathy or CHF. Jaundice arises from hepatic dysfunction with elevated bilirubin, not directly from cardiac failure. Muffled heart sounds are a feature of cardiac tamponade, not cardiomyopathy.

Correct answer: A. Assess the apical pulse rate for one full minute

Prior to each digoxin dose, the nurse must measure the child's apical pulse for a full minute to detect bradycardia, which is a key indicator of digoxin toxicity. If the heart rate falls below age-specific thresholds (typically less than 90-110 bpm in infants or less than 70 bpm in older children), the dose must be held and the provider notified. The symptoms of decreased appetite, nausea, and fatigue described are consistent with early toxicity. Serum electrolytes — particularly potassium, calcium, and magnesium — should also be monitored, as hypokalemia, hypercalcemia, and hypomagnesemia potentiate toxicity even when digoxin levels remain within the therapeutic range of 0.5-2 ng/mL. Lung auscultation is relevant for assessing fluid status but does not directly guide digoxin safety. Temperature measurement is unrelated. Liver function is not the priority because digoxin is renally, not hepatically, cleared.

Correct answer: B. Tetralogy of Fallot (TOF)

Tetralogy of Fallot (TOF) is defined by four structural abnormalities: ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta. Exertion such as feeding or crying increases right-to-left shunting of deoxygenated blood, worsening cyanosis. The murmur is produced by right ventricular outflow obstruction. TOF is the most prevalent cyanotic congenital heart disease and requires surgical repair. TGA also causes cyanosis but presents with profound desaturation immediately postnatally requiring ductal or septal patency for survival. TAPVR involves aberrant pulmonary venous drainage to the right atrium, producing severe cyanosis and pulmonary congestion without the four-defect cluster of TOF. Tricuspid atresia features an underdeveloped right ventricle with reduced pulmonary flow but lacks the characteristic right ventricular outflow obstruction murmur of TOF.