LAUSR

A 5-month-old infant with total parenteral nutrition (TPN) dependence due to short bowel syndrome (SBS) and prior mechanical mitral valve replacement for endocarditis was referred for difficulty achieving her goal international normalized ratio (INR) while on oral warfarin. The patient was born preterm at 32 weeks. Her prenatal anatomy scan showed multiple cystic structures in the lower abdomen concerning for a suspected fetal bowel obstruction. Her radiography at birth showed a jejunal atresia with a dilated distal pouch and no contrast seen beyond the distal descending colon with a small colonic caliber. Upon emergent laparotomy, she was confirmed to have congenital jejunal atresia, in utero midgut volvulus, and microcolon. After the excision of the necrotic bowel and primary anastomosis, the patient was left with 9 cm (cm) of jejunum and 2 cm of terminal ileum/microcolon. The pathology of the excised remnant showed a segment of atretic small bowel with dystrophic calcifications and serosal adhesions. The infant was started on TPN supplemented with a lipid emulsion of mixed soya oil, medium chain triglycerides (MCT), olive oil, and fish oil (SMOF) on day of life (DoL) 2. She continued to need TPN for nutritional support due to persistent intolerance of expressed breast milk (EBM) beyond 1–2 milliLiters (mL)/hour (h) through a gastrostomy tube (GT). When the patient was 6 weeks old, she was transferred to Lucile Packard Stanford Children’s Hospital for Enterococcus faecalis bacteremia complicated with endocarditis. Her echocardiogram showed large mitral valve vegetations, significant mitral valve insufficiency, dilatation of the left atrium, increasing pulmonary backflow and pulmonary edema, suggestive of pulmonary hypertension. A mechanical mitral valve was placed on DoL 52. An infusion of bivalirudin was started to bridge her until she achieved therapeutic target range (TTR) of her goal INR between 2.5 and 3.5 while taking oral warfarin. Oral warfarin therapy was the only long-term anticoagulation therapy adequate to preserve the functionality of her mechanical mitral valve so as to prevent sudden death; achieving TTR on oral warfarin therapy was essential for the patient’s survival. To reach her goal INR, we had to balance her oral warfarin and vitamin K intake. The patient was unable to achieve TTR despite increasing the dose of oral warfarin. She was