A post-Fontan patient’s ECG shows a regular atrial rate of approximately 300 bpm with sawtooth-appearing waves in the inferior leads and a ventricular rate of 150 bpm. What is the most likely diagnosis?

A 16-year-old female with known Graves disease, non-adherent to methimazole for 3 months, undergoes emergency appendectomy. Five hours post-operatively, she develops fever of 40.3°C, HR 162 bpm, agitation, tremors, and severe diaphoresis. BP is 178/100 mmHg. Burch-Wartofsky score is 75. Which management sequence is CORRECT for thyroid storm?

A neonate with truncus arteriosus develops perioral tetany and a seizure shortly after birth. Which evaluation should be prioritized immediately, and what associated condition is suggested?

An infant with Trisomy 21 has a murmur and signs of heart failure. ECG shows left axis deviation and first-degree AV block. Which cardiac lesion is most likely, and by what age should repair typically occur to prevent irreversible pulmonary hypertension?

A child with Noonan syndrome is scheduled for cardiac catheterization for pulmonary valve stenosis. Which additional preoperative evaluation is most important given this syndrome’s associations?

A 4-week-old with a confirmed 22q11.2 deletion requires a packed red blood cell transfusion for post-cardiac surgery anemia. The blood bank is contacted. Which specification for blood products is MOST appropriate for this patient?

A 10-year-old with newly diagnosed Crohn disease has terminal ileitis and ascending colon involvement confirmed on colonoscopy and MR enterography. CRP 72 mg/L, albumin 2.6 g/dL. The family is strongly opposed to corticosteroids. Which induction therapy has the STRONGEST evidence in pediatric Crohn and is preferred by current guidelines as an alternative to steroids?

A 16-year-old with Marfan syndrome is being followed for aortic root dilation. Which combination of recommendations is most appropriate?

A child on chronic digoxin therapy for CHF develops new bigeminy and is found to have a potassium level of 2.9 mEq/L. What is the most appropriate initial step in management?

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