Portopulmonary hypertension (PTPH) is a special type of pulmonary hypertension. Pulmonary hypertension is high blood pressure in the pulmonary arteries that carry unoxygenated blood from the right ventricle of the heart to the lungs. Pulmonary hypertension results from constriction, or tightening, of the blood vessels that supply blood to the lungs. Consequently, it becomes difficult for blood to pass through the lungs, making it harder for the heart to pump blood forward. This stress on the heart leads to enlargement of the heart and eventually fluid can build up in the liver and tissues, such as in the legs. Affected patients can sometimes notice increasing shortness of breath and dizziness.