In anomalous pulmonary venous drainage, the lung veins plug into the wrong chamber or vessel. Oxygen-rich blood is sent on a detour, so the body runs low on fuel and the heart works overtime.

Blue lips and fingertips are the giveaway. The color is faint at rest, deepens with crying or feeding, and doesn’t improve with extra oxygen.

Fast, labored breathing starts early. Infants use more breaths per minute and may grunt with each exhale.

Poor weight gain follows. Babies tire at the bottle, fall asleep quickly, and don’t add ounces like their peers.

Heart murmur is loud. A washing-machine sound is heard even without a stethoscope.

Swelling shows late. Ankles, feet, or belly puff if the heart begins to fail.

Late alarms include sudden collapse, severe cyanosis, or stroke-like weakness—signs the detour is critically blocked.