Lurie Children’s offers the Pulmonary Hypertension Service to care for children of all ages with pulmonary hypertension (PH). PH is a disease of the very small blood vessels within the lungs. When they become narrowed, scarred or clotted, it is more difficult for blood to pass through the vessels. The right side of the heart then has to work harder to pump blood through these vessels. Therefore, pulmonary hypertension affects not only the lungs but the heart as well.