This case involves a 10-year-old female patient with Down syndrome that underwent a surgical procedure to repair a hole between her heart chambers and regulate her blood flow. She underwent a subsequent open-heart procedure to remove scar tissue from a stenotic mitral valve. During the surgery, she required intravenous cannulation via the groin with the arterial cannula in the femoral artery. After the surgery was completed, her leg appeared purple, cold, and swollen. After a few hours of observation, the color returned to the leg, but the pain continued to increase. Ultrasounds showed poor circulation to the superficial femoral and popliteal artery. Vascular surgery was consulted and diagnosed the patient with compartment syndrome. Vascular surgery performed a thromboembolectomy to remove the blood clot. However, it was felt to be too late to surgically remove the connective tissue to relieve the pressure, as the muscle damage had already occurred. The patient was left with permanent deformity, scarring, and disability and required ongoing therapy.