In most of these infants, symptoms of myocardial ischemia, congestive heart failure, or myocardial infarction appear between 2 weeks and 6 months after birth, and include recurrent episodes of restlessness, irritability, incessant crying, and dyspnea, often associated with pallor and sweating. These episodes are most frequent during feeding, which corresponds to physical exertion for the infant. Irritability and crying are attributed to angina pectoris. Signs of congestive heart failure may be present, including tachypnea, tachycardia, gallop rhythm, cardiomegaly, and hepatomegaly. A murmur of mitral insufficiency may be heard, the result of infarction of a papillary muscle.