What is PH?
PH = Pulmonary Hypertension
Pulmonary = the lungs
Hypertension = high blood pressure
PH is a disease of abnormally high blood pressure in the pulmonary arteries. In PH, the pulmonary arteries become narrowed, and can be scarred to the point of being closed.
Patients with PH develop symptoms such as shortness of breath, tiredness, and swelling of the feet and ankles.
PH is a serious illness, and can be life-threatening.
How does PH affect the body?
PH is a disease of abnormally high blood pressure in the arteries of the lungs (also known as pulmonary arteries). The pulmonary arteries become narrowed, and can be scarred to the point of being closed.
The narrowing of the pulmonary arteries means the right ventricle (RV = lower chamber on the right side) of the heart has to work harder to pump blood through the lungs. Because the RV of the heart has to work harder in PH, it is the RV that eventually gets weak, leading to RV failure, a type of heart failure. Heart failure means the heart cannot pump enough blood for the body’s needs. There is reduced blood flow to the organs of the body and patients with PH may have low blood oxygen levels. Reduced blood flow causes the symptoms of difficulty breathing, fatigue, chest pain, and faintness.
Other blood vessels of the lungs can also be affected by PH. This includes the smallest capillaries, and sometimes the pulmonary veins (which carry blood from the lungs back to the left-side of the heart).
If PH is not treated, the RV of the heart will eventually fail in many PH patients, which may lead to death.
Who gets PH?
PH can strike anyone. It typically affects people between 20 and 60 years of age, but PH can also affect children and the elderly. PH affects both men and women. However, certain types of PH are more common in females:
idiopathic PAH (IPAH, previously known as PPH)
PAH associated with connective tissue disease like scleroderma
Some people are more likely to develop PH. Factors that increase the risk of a person developing PH include:
A family history of a close relative being affected by PH
The use of appetite-suppressant medications for weight loss (for example, fenfluramine or abuse of recreational drugs (for example, cocaine)
A history of blood clots in the lungs (also known as pulmonary emboli)
The presence of other medical conditions, including lung disease (for example, emphysema), heart disease (for example, heart failure), and general medical conditions (for example, connective tissue disease like scleroderma).
What is happening to the arteries of my lungs in PH?
The arteries of the lungs (also known as pulmonary arteries) normally carry blood from the right ventricle (RV; lower chamber on the right-side of the heart) to the lungs.
In normal humans without PH, the pulmonary arteries are relaxed, wide open, and are not stiff, so that blood flows very easily through the lungs. For this reason, blood pressure in the pulmonary arteries is normally very low.
In normal humans, the blood pressure in the pulmonary arteries (also known as pulmonary artery pressure = PAP) normally fluctuates continuously:
PAP fluctuates between a high value (also known as systolic) of about 25 millimeters of mercury (= mm Hg) and a low value (also known as diastolic) of 10 mmHg. Thus, the PAP is said to be 25/10 mm Hg
The average PAP (also known as mean PAP) is usually between 15-20 mmHg, but is always less than 25 mmHg in normal humans at rest
PH is often due to disease in the smallest pulmonary arteries. These pulmonary arteries are narrowed, and some may even be closed, because of several abnormalities:
The walls of the pulmonary arteries are thicker and stiffer
There is scar tissue (also known as fibrosis) in the walls of the pulmonary arteries
There are more cells in the walls of the pulmonary arteries. This is because cells have multiplied (also known as divided or proliferated) abnormally to create more cells. These cells include:
The inner lining cells (also known as endothelial cells) of the pulmonary arteries
The smooth muscle cells that contract to cause spasm of pulmonary arteries
The cells that make scar tissue (also known as fibroblasts)
In PH, because of the narrowed and closed pulmonary arteries, the lungs may grow new blood vessels. These new blood vessels are often very small, and twisted, and form little balls of blood vessels called “plexiform lesions”.
Because of the high blood pressure in the lungs in PH, the large pulmonary arteries can enlarge (also known as dilate). This can be seen on a chest x-ray or CT scan of the lungs.