The nurse is caring for an infant who was recently diagnosed with a congenital heart defect. Which assessment finding is most important for the nurse to report to the healthcare provider?

A. Many infants with congenital heart defects exhibit audible murmurs due to turbulent blood flow through abnormal openings or stenotic valves. While a murmur is a diagnostic hallmark of the condition, it is often an expected finding and does not necessarily indicate acute physiological deterioration. The nurse must document the murmur, but it is rarely the most urgent finding to report. B. A heart rate of 162 beats/minute in an infant is slightly elevated above the typical resting range but can be triggered by crying, feeding, or baseline cardiac stress from the defect. Although tachycardia requires close monitoring to ensure the infant is not entering a state of high-output failure, it is less critical than signs of fluid overload. It represents a compensatory mechanism rather than an immediate life-threatening complication. C. Infants with cardiac defects often experience fatigue during feeding because of the high metabolic demand and decreased cardiac output. Poor suckling effort and inadequate oral intake are common symptoms of pediatric heart failure that lead to failure to thrive over time. While this finding is significant for long-term nutritional management, it does not suggest an acute, rapid shift in stability like sudden weight changes. D. Rapid weight gain of 1 kg within 48 hours is the most critical finding because it indicates acute fluid volume excess and potential congestive heart failure. In an infant, such a significant increase is almost certainly due to fluid retention rather than nutritional growth. This clinical sign suggests that the heart is unable to manage the systemic or pulmonary circulation effectively, necessitating immediate medical intervention.