Approximately 15,200 children receive cardiopulmonary resuscitation (CPR) for in-hospital cardiac arrest (IHCA) each year in the United States. Of these, about 60% are less than one year of age. Most IHCA (85-90%) occurs in intensive care units (ICU) or other monitored settings. Risk of IHCA is higher among children with cardiac disease compared to children with other diagnoses. A report based on the Pediatric Cardiac Critical Care Consortium (PC4) registry found 3.1% of children hospitalized in pediatric cardiac ICUs had a cardiac arrest; rates varied from 1% to 5.5 % across sites. Survival to hospital discharge after CA in children included in the PC4 registry was 53%, and lower for medical cardiac patients (37.7%) than for surgical cardiac patients (62.5%). Among survivors of pediatric IHCA, neurologic morbidities are common including cognitive, motor, and adaptive functional deficits. Despite high mortality and morbidity, treatment for children after IHCA is mainly supportive. Preventing fever and hypotension, maintaining normoxia, and treating seizures are emphasized. Ischemia-reperfusion injury to the brain is a primary cause of neurologic morbidity after IHCA. Ischemia-reperfusion leads to increased production of cytotoxic mitochondrial reactive oxygen species (ROS). Recently, specific wavelengths of near infrared light (NIR) (750 nm and 950 nm) have been discovered to partially inhibit cytochrome c oxidase activity (COX), reversibly reducing mitochondrial respiration and generation of ROS. Light Utilization COX Inhibitory Device (LUCID) is a novel medical device intended to safely deliver therapeutic NIR to the infant brain to prevent reperfusion injury. This protocol describes the "LUCID Therapy for Infant Cardiac Arrest" (LUTICA) clinical trial. LUTICA will investigate the safety, feasibility, acceptability, and probable benefit of the LUCID device in infants with acquired or congenital cardiac disease who experience unplanned IHCA. The hypothesis of the LUTICA trial is that application of the LUCID light box and cap immediately following IHCA in infants with acquired or congenital heart disease will be safe, feasible, and acceptable in the ICU setting, and demonstrate probable benefit toward favorable neurological outcomes.