A 2-year-old boy presents with recurrent cyanotic episodes triggered by crying and exertion. Vital signs show HR 128/min, RR 32/min, BP 95/60 mmHg, SpO2 78% during distress. Physical examination reveals a harsh systolic ejection murmur at the left upper sternal border. Chest X-ray demonstrates a "boot-shaped" heart with right ventricular hypertrophy. The patient spontaneously assumes a squatting posture during cyanotic spells, which temporarily improves his oxygen saturation. No hepatomegaly is noted. Which embryologic defect is most closely associated with this condition?
- A)Failure of neural crest migration causing conotruncal malalignmentGABARITO
- B)Persistence of the left superior vena cava
- C)Excess apoptosis of the tricuspid leaflets
- D)Failure of endocardial cushion fusion only
- E)Incomplete closure of the ductus venosus
Explicação
Failure of neural crest migration causing conotruncal malalignment is correct. Tetralogy of Fallot results from anterosuperior displacement of the infundibular septum, leading to pulmonary stenosis, right ventricular hypertrophy, ventricular septal defect, and... Ver explicação completa e trilha adaptativa →