Pressure helps blood flow through blood vessels. Hypertension occurs when this pressure gets too high. When this happens in the blood vessels in the lungs, it is called pulmonary hypertension.

Pressure may rise for any number of reasons. It creates a potentially serious condition. The right side of the heart needs to pump harder to move blood against the pressure. If left untreated, the right side of the heart can eventually fail.

Heart and Lungs
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The blood vessels in the lungs are very sensitive to oxygen. The lower the level of oxygen, the narrower the vessels become. Higher pressure will be needed to push blood through the narrow blood vessels. Pressure will also increase when there is more blood in the lungs than normal.

There are many different causes of pulmonary hypertension in children, such as:

Pulmonary hypertension can also be inherited. This is called familial pulmonary hypertension. In other cases, the cause is unknown.