- Prenatal screening: Some heart defects can be detected before birth using ultrasounds. - Echocardiogram: An ultrasound of the heart that provides detailed images of its structure and function. - Electrocardiogram (ECG): A test that measures the electrical activity of the heart. - Chest X-ray: Helps visualize the heart's size and shape. - Pulse oximetry: Measures the oxygen level in the blood and can help identify cyanotic heart defects.