PPH and the Cardiovascular System

The heart pumps blood from the right ventricle into the lungs through the pulmonary artery. The lungs then supply oxygen to the blood and capture carbon dioxide and other waste materials to be eliminated during exhalation. The blood then flows back to the heart, where the left ventricle pumps it throughout the body. The pumping action of the heart generates the blood flow; blood pressure is generated by resistance to this blood flow. If there is high resistance to this blood flow, then blood pressure rises. Hypertension is a medical term meaning that the blood pressure is higher than normal or that the resistance to blood flow is causing the blood pressure to be at an elevated state.
The normal pressure in the pulmonary artery is between 14 and 18 mm Hg. For patients with pulmonary hypertension, the pressure is normally about 30 to 50% higher or 25 to 30 mmHg. This high pressure has been linked to certain changes in the small blood vessels in the lungs. As the resistance to blood flow in these small vessels increases, it is harder for blood to flow through them and so the blood "backs up." This action causes the blood pressure in the pulmonary artery, which feeds these small lung vessels, to increase. PPH has also been shown to result from narrowing of the pulmonary artery. As this large artery narrows, the force required to pump blood through the artery increases and thus the pressure in the artery increases.


Deaths from PPH
Primary pulmonary hypertension has no cure. If left untreated, the right side of the heart becomes overworked and eventually fails, leading to death. One study showed that 30% of untreated PPH patients died within 3 years of diagnosis. New treatments for PPH, developed during the 1990's, have helped to relieve the symptoms and improve the quality of life of PPH patients.