In infants, which signs are indicative of heart failure?

The signs indicative of heart failure in infants include tachycardia, diaphoresis, and fatigue. Tachycardia, or an increased heart rate, is a common response as the heart works harder to compensate for reduced cardiac output. Diaphoresis, or sweating, occurs even with minimal exertion, as the body struggles to manage the workload placed on the heart. Fatigue is also notable, as the infant may become excessively tired due to the effort required for feeding or even during normal activities. These signs collectively suggest that the infant's heart is not functioning effectively, which is a hallmark of heart failure.

In contrast, the other signs mentioned in the other options can indicate various conditions but are not as specifically linked to heart failure. For instance, weight gain and failure to thrive might seem related to heart issues but can also be associated with other medical problems not directly involving heart function. Similarly, poor feeding and bradycardia may showcase other underlying conditions and are not definitive indicators of heart failure, making them less indicative of this serious condition.