A 14-year-old girl collapses while swimming and regains consciousness spontaneously. Her maternal uncle died suddenly at age 22. Vital signs show BP 118/76 mmHg, HR 92 bpm, RR 16/min, temp 37°C, SpO2 98% on room air. ECG reveals a prolonged QT interval of 520 ms. Serum electrolytes, including potassium and magnesium, are normal. She denies palpitations or chest pain. Which of the following is the most likely underlying mechanism?
- A)Defective desmosomal proteins in the right ventricle
- B)Accessory AV pathway causing preexcitation
- C)Mutation causing delayed ventricular repolarizationGABARITO
- D)Fibrofatty replacement of the interventricular septum
- E)Autoimmune destruction of the AV node
Explicação
Congenital long QT syndrome predisposes to syncope and sudden death due to torsades de pointes. The core problem is delayed ventricular repolarization, usually from inherited ion channel abnormalities affecting potassium or sodium currents, which prolong the a... Ver explicação completa e trilha adaptativa →