A 10-year-old boy who recently immigrated from overseas with his family is brought to the office due to exertional dyspnea and fatigability. The boy tires easily when walking and cannot keep up with his peers at the playground. According to his parents, he was diagnosed with congenital heart disease in infancy, but corrective surgery was unavailable. They cannot recall the details of his diagnosis. He takes a daily multivitamin and no medications. Pulse oximetry of the right hand shows 99% on room air. Physical examination reveals no murmurs. There is bilateral cyanosis and clubbing of the toes. The fingers are normal. All extremity pulses are full and equal. Which of the following is the most likely diagnosis?

Question

A 10-year-old boy who recently immigrated from overseas with his family is brought to the office due to exertional dyspnea and fatigability.  The boy tires easily when walking and cannot keep up with his peers at the playground.  According to his parents, he was diagnosed with congenital heart disease in infancy, but corrective surgery was unavailable.  They cannot recall the details of his diagnosis.  He takes a daily multivitamin and no medications.  Pulse oximetry of the right hand shows 99% on room air.  Physical examination reveals no murmurs.  There is bilateral cyanosis and clubbing of the toes.  The fingers are normal.  All extremity pulses are full and equal.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec160b_38de_a78f_9249_81e3eabf12e9_MD0001_00 This patient with cyanosis and clubbing of the feet but normal peripheral pulses most likely has a large patent ductus arteriosus (PDA). A PDA initially results in a left-to-right shunt with increased pulmonary blood flow. Over time, this can lead to increased pulmonary vascular resistance (PVR) due to progressive vascular remodeling. If the shunt is not corrected, PVR can eventually exceed systemic resistance and cause reversal of the shunt to right-to-left blood flow (ie, Eisenmenger syndrome), resulting in arterial hypoxemia, cyanosis, and eventually clubbing. Differential clubbing and cyanosis in the lower extremities occurs when there is a significant decrease in postductal oxygen saturation (the arteries perfusing the head and upper extremities arise proximal to the ductus). In patients with a PDA and Eisenmenger syndrome, the upper extremities are supplied by oxygenated blood from the left ventricle, but deoxygenated blood flows right-to-left across the PDA and supplies the descending aorta, resulting in lower body hypoxemia and cyanosis of the toes. Although left-to-right shunting through a PDA typically causes a continuous murmur, this murmur disappears once right-to-left shunting and Eisenmenger syndrome develops due to the lower transductal pressure gradient; some patients will develop a murmur of tricuspid regurgitation due to progressive RV enlargement. (Choices A and E) Atrial and ventricular septal defects initially involve left-to-right intracardiac shunting and are therefore acyanotic at birth. Large septal defects are at risk for shunt reversal and Eisenmenger syndrome; however, since the right-to-left shunt is intracardiac, cyanosis and clubbing affect the upper and lower extremities equally. (Choice C) Tetralogy of Fallot is generally characterized by spells of cyanosis due to transient right-to-left shunting across the ventricular septal defect. Because the right-to-left shunt is intracardiac, cyanosis typically involves the whole body. (Choice D) Differential clubbing and cyanosis can occur with uncorrected transposition of the great arteries when there is extracardiac shunting through a PDA to allow mixing between the two parallel blood circuits. However, the cyanosis will be present in the upper extremities and not the lower extremities, as oxygenated blood will flow across the PDA into the descending aorta (ie, postductal oxygen saturation is higher). Educational objective: Lower extremity differential clubbing and cyanosis without pulse discrepancy is caused by a large patent ductus arteriosus complicated by Eisenmenger syndrome (reversal of shunt flow from left-to-right to right-to-left). In contrast, intracardiac right-to-left shunting in patients with large septal defects and Tetralogy of Fallot results in whole-body cyanosis.

A 10-Year-Old Boy Who Recently Immigrated from Overseas with His