Cyanotic Heart Disease refers to a group of congenital heart defects that result in low oxygen levels in the blood, leading to a bluish tint to the skin, lips, and nails, known as cyanosis. This condition occurs when oxygen-rich blood is mixed with oxygen-poor blood, often due to structural abnormalities in the heart, such as tetralogy of Fallot or transposition of the great arteries. Diagnosis typically involves physical examinations, imaging tests like echocardiograms, and pulse oximetry to measure oxygen saturation. Treatment may include medications, surgical interventions, or catheter-based procedures to correct the heart's structure and improve blood flow, ultimately enhancing oxygen delivery to the body.