Due to innovations in pediatric cardiothoracic surgery, individuals with congenital heart disease (CHD) are now living into adulthood. Adolescents with CHD often require intensive care admissions post-surgery, which can lead to long-term neurodevelopmental and psychiatric consequences, impacting their ability to achieve healthcare autonomy. Nurses face challenges in providing care tailored to adolescents' developmental needs, and research on their experiences is scarce. This dissertation study used qualitative interviews of twenty nurses to explore their experiences with post-operative adolescent cardiac patients. Aims included: 1) to describe how nurses integrated and met the physical, psychosocial and relational needs in care encounters with critically ill postoperative adolescent cardiac surgical patients; 2) to elicit nurse’s perceptions of trust within the nurse-patient relationship when caring for critically ill post-operative adolescent cardiac surgical patient; and 3) to describe policies and system level factors that supported care integration and relationship development for the critically ill post-operative adolescent cardiac surgical patient. The study employed a semi-structured interview guide based on the Fundamentals of Care Framework (FOC) and the Consolidated Framework for Implementation Research (CFIR). Data was analyzed with conventional content analysis in NVivo software by two coders and themes were developed. Nurses reported experiencing heavy workloads accompanied by significant emotional strain, complex communication demands, and shifting family dynamics. Nurses described a need for additional resources, support and clinical training related to nursing care for critically ill adolescents post-operative cardiac surgery. Results aimed to improve nursing interventions for critically ill adolescents and to better support nursing staff.