Cyanotic heart defects are a group of congenital heart conditions that result in low oxygen levels in the blood, leading to a bluish tint to the skin, lips, and nails, known as cyanosis. These defects occur when the heart's structure is abnormal, affecting how blood flows through the heart and to the rest of the body. Common types include Tetralogy of Fallot and Transposition of the Great Arteries. Diagnosis typically occurs shortly after birth, and symptoms may include difficulty breathing, fatigue, and poor weight gain. Treatment often involves surgery to correct the heart's structure and improve blood flow. Early intervention is crucial for better outcomes in affected infants and children.