A heart murmur in infants with pneumonia may be pathological or physiological. The pathological condition may be related to the child’s congenital heart disease or a weakness in the child’s constitution, which may result in damage to the heart muscle due to toxins produced by pathogens that are not expelled from the body in a timely manner, combined with incomplete closure of the heart valves. It is often seen in cases such as myocarditis and heart failure. Physiology is mostly due to the fact that the baby’s body systems are not yet well developed. It is caused by a decrease in body mass during the onset of pneumonia, or due to fever, etc. The nature of the murmur should be determined based on the results of the child’s cardiac enzymes and electrocardiogram, and treated as prescribed by the doctor.