Tricuspid atresia means the right-side inlet valve never formed, so blood must detour through a hole in the heart or a vessel shortcut. Symptoms start in the first days of life and are impossible to miss.

Blue color is the first clue. Lips, tongue, or fingertips look dusky or deep purple, especially when the baby cries or feeds.

Fast breathing is constant. The infant uses more breaths per minute than peers and may grunt with each exhale.

Poor feeding and slow weight gain follow. Babies tire quickly, fall asleep at the bottle, and don’t add ounces.

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

Sweating and cold hands appear during feeds. The body works overtime to move blood, so skin feels cool and damp.

Sudden deeper blue spells or fainting mean the detour is kinking—an alarm that blood flow is critically low.