Hypoplastic left heart

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Heart, front view

Heart, section through the middle

Hypoplastic left heart describes the underdevelopment of the left side of the heart (mitral valve, aortic valve, and aorta). The condition is congenital (present at birth).

Hypoplastic left heart syndrome; HLHS

Hypoplastic left heart is a rare type of congenital heart disease. It affects less than 2 in every 10,000 live births.

The problem develops before birth when there is inadequate growth of the left ventricle and associated structures (aortic and mitral valves that guard the exit and entrance of the ventricle and the aorta which is the blood vessel that carries oxygenated blood from the left ventricle to the entire body).

In patients with this condition, the left side of the heart is unable to maintain blood circulation for the body. As a result, the right side of the heart must maintain the circulation for both the lungs and the body. This extra workload eventually causes the heart to fail.

The only possibility of survival is a connection between the right and the left side of the heart through which blood may pass. This is called a shunt. Babies are normally born with two of these connections (the foramen ovale and the ductus arteriosus), which spontaneously close a few days after birth.

If these structures are allowed to close in a baby with hypoplastic left heart syndrome, however, the patient will quickly die because no blood will be pumped to the body.

As with most congenital heart defects, there is no known cause. Around 10% of patients with hypoplastic left heart syndrome will have other birth defects.

Review Date: 05/30/2006
Reviewed By: Anne J. L. Chun, M.D., Assistant Professor of Pediatrics, Division of Pediatric Cardiology, New York University School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.