Initially, a newborn with hypoplastic left heart may appear normal. Symptoms usually occur in the first few hours of life, although it may take up to a few days to develop symptoms. These symptoms may include:

• Lethargy
• Poor suckling and feeding
• Shortness of breath
• Rapid breathing
• Cold extremities
• Enlarged liver
• Poor pulse
• Pounding heart
• Bluish or poor skin color
• Sudden death

However, a bluish color observed in the chest or abdomen, lips, and tongue is abnormal (called central cyanosis) because it reflects lack of adequate levels of oxygen in the blood. This is secondary to the heart malformation and circulatory malfunction. Central cyanosis often increases with crying.

A physical examination usually reveals a blue, critically ill patient who may show signs of congestive heart failure, liver enlargement, rapid breathing, and lethargy. Additionally, the pulse at various locations (wrist, groin, and others) is usually very weak.

Tests:

• An ECG shows enlargement of the right ventricle of the heart.
• An x-ray of the chest shows heart enlargement.
• An echocardiogram for the definitive diagnosis shows the tiny left ventricle
• A cardiac catheterization may be necessary in some cases to complement the echocardiogram.