A 1–month–old boy is referred for failure to thrive. On examination, he shows feature of congestive failure. The femoral pulses are feeble as compared to brachial pulses. The most likely clinical diagnosis is –
Feeble femoral pulsations compared to strong brachial pulsations suggests the diagnosis of coarctation of aorta. Hypertension and strong pulsations in the upper extremities and absence, marked dimunition or delay in pulsations in the femoral artery are characteristic in coarctation. Also failure to thrive and congestive heart failure are consistent with the diagnosis of congestive heart failure.
Remember: 

Differential cyanosis is a manifestation of PDA
Differential pulses/Blood pressure is a manifestation of Coarctation
Congenital aortic stenosis
Coarctation of aorta
Patent ductus arteriosus
Congenital aortoiliac disease