A 3-year-old boy is brought to the emergency department due to loss of consciousness while playing at a park. The boy was short of breath from running when he appeared blue and went limp for approximately 10 seconds. His mother caught his fall and says that he regained consciousness quickly. He did not hit his head or experience any trauma. However, the patient has previously lost consciousness during excess crying and temper tantrums. The events are brief and accompanied by blue discoloration of his lips. The patient was born full term via normal vaginal delivery, and there was no known history of cyanosis or jaundice in the neonatal period. He has met all developmental milestones. The patient's father has hypertension and hyperlipidemia, and his paternal uncle has a seizure disorder. Temperature is 37.5 C (99.5 F), pulse is 110/min, and respirations are 45/min. Physical examination shows an alert and mildly cyanotic boy with a systolic ejection murmur along the mid to upper left sternal border. When the child squats, the murmur becomes louder and the cyanosis improves. The abdomen is soft, nontender, and nondistended. No organomegaly is present. Femoral and brachial pulses are equal and 2+. Deep tendon reflexes are 2+. Which of the following is the most likely diagnosis in this patient?

Question

A 3-year-old boy is brought to the emergency department due to loss of consciousness while playing at a park.  The boy was short of breath from running when he appeared blue and went limp for approximately 10 seconds.  His mother caught his fall and says that he regained consciousness quickly.  He did not hit his head or experience any trauma.  However, the patient has previously lost consciousness during excess crying and temper tantrums.  The events are brief and accompanied by blue discoloration of his lips.  The patient was born full term via normal vaginal delivery, and there was no known history of cyanosis or jaundice in the neonatal period.  He has met all developmental milestones.  The patient's father has hypertension and hyperlipidemia, and his paternal uncle has a seizure disorder.  Temperature is 37.5 C (99.5 F), pulse is 110/min, and respirations are 45/min.  Physical examination shows an alert and mildly cyanotic boy with a systolic ejection murmur along the mid to upper left sternal border.  When the child squats, the murmur becomes louder and the cyanosis improves.  The abdomen is soft, nontender, and nondistended.  No organomegaly is present.  Femoral and brachial pulses are equal and 2+.  Deep tendon reflexes are 2+.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d63a_b0af_bc81_e5797f01c7b9_MD0003_00 Tetralogy of Fallot is the most common congenital heart disease with the following defects: Ventricular septal defect Overriding aorta over the right and left ventricles Right ventricular outflow tract (RVOT) obstruction Right ventricular hypertrophy The clinical presentation depends on the severity of RVOT obstruction resulting from pulmonary stenosis. Severe RVOT obstruction typically presents shortly after birth with central (eg, perioral) cyanosis. However, moderate obstruction may cause subtle symptoms during infancy and instead present during childhood with sudden hypoxic/hypercyanotic "tet" spells due to right-to-left shunting during exertion or agitation. Additional sequelae include exertional dyspnea and syncope. Examination may reveal a harsh, systolic ejection murmur over the mid to left upper sternal border due to RVOT obstruction. Squatting may reduce symptoms (eg, cyanosis) and increases the intensity of the systolic murmur. This maneuver increases the systemic vascular resistance (afterload) and decreases the right-to-left shunting across the ventricular septal defect, which thereby increases flow across the RVOT. (Choice A) Absence epilepsy manifests as abrupt, intermittent periods of loss of consciousness without loss of body tone, which is unlikely in this patient who went limp during the syncopal event. (Choice B) Breath-holding spells present with cyanosis and loss of consciousness following an emotional event. The cyanosis should resolve promptly after the event and the examination should be normal. (Choice C) Generalized seizures almost always have a delayed return to baseline neurologic functioning due to a postictal state of transient confusion, lethargy, and/or focal neurologic deficits. This patient is alert. (Choice D) Hypertrophic cardiomyopathy can cause cardiogenic syncope due to left ventricular outflow tract obstruction. A systolic murmur that is best heard at the apex and lower left sternal border is diminished by maneuvers that increase systemic vascular resistance (eg, squatting, handgrip). Hypertrophic cardiomyopathy (Choice E) Isolated atrial septal defect is an acyanotic lesion that causes a wide and fixed splitting of S2 and a systolic ejection murmur due to increased blood flow across the pulmonic valve. atrial septal defect (Choice G) Vasovagal syncope is loss of consciousness with loss of postural tone, often in response to sudden emotional stress. However, cyanosis and murmur should raise suspicion for a cardiogenic etiology. Educational objective: Tetralogy of Fallot can present with hypercyanotic "tet" spells due to right ventricular outflow tract (RVOT) obstruction and right-to-left shunting in the setting of exertion or agitation. Squatting increases afterload, which increases blood flow across the RVOT, which in turn improves cyanosis. References: Tetralogy of Fallot: fetal diagnosis to surgical correction. (http://www.ncbi.nlm.nih.gov/pubmed/22992529)

A 3-Year-Old Boy Is Brought to the Emergency Department Due