The interior of the heart is composed of valves, chambers, and associated vessels.

The external structures of the heart include the ventricles, atria, arteries and veins. Arteries carry blood away from the heart while veins carry blood into the heart. The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

This is a normal fetal ultrasound showing one pattern of the fetal heartbeat. Some ultrasound machines have the ability to focus on different areas of the heart and evaluate the heartbeat. This is useful in the early diagnosis of congenital heart abnormalities.

This is an ultrasound showing a ventricular septal defect pattern of the fetal heartbeat. Some ultrasound machines have the ability to focus on different areas of the heart and evaluate the heartbeat. This is useful in the early diagnosis of congenital heart abnormalities.

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