Pulmonary Hypertension


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is pulmonary hypertension?

Pulmonary hypertension is any condition in which there is higher-than-normal high blood pressure in the blood vessels of the lungs and in the blood vessels from which blood travels to the lungs from the right side of the heart. Understanding the basics of this condition requires a summary of the anatomy of the circulatory system. Although you have one heart, consisting of four chambers (two atria and two ventricles), there are two circuits, or pathways, through which blood travels. In one pathway, known as the systemic vasculature, the left side of the heart pumps blood through arteries and through body tissues, from which a series of veins carry the blood to the right side of the heart. In the other pathway, known as the pulmonary vasculature, the right side of the heart pumps blood through arteries and through the lungs, from which veins return the blood to the heart, this time to the left side, which pumps it through the body once again.

To add just a little more detail, venous blood returning from body tissues enters into the hearts right atrium. After the right atrium fills, it contracts, pumping the blood through a valve called the tricuspid valve into the right ventricle. When the right ventricle contracts, the blood then passes through the pulmonary valve into the pulmonary artery, which successively branches into an increasing number of smaller arteries, and then into arterioles, which branch into capillaries surrounding air sacks, where blood releases carbon dioxide and receives oxygen. Freshly oxygenated blood then moves through veins of increasing size that finally come together into four pulmonary veins (two from each lung), which in turn deliver the blood to the hearts left atrium. From there, the oxygenated blood is pumped through the bicuspid valve (also called the mitral valve) into the left ventricle. When the left ventricle contracts, it sends the blood through the aortic valve into the aorta, the largest artery in the body, from which blood then is channeled into an increasing number of smaller vessels that deliver the blood to body tissues. From there, the blood goes through the systemic venous system until it reaches the right atrium, and the cycle begins again.

Because the systemic blood must travel through great distances and a large mass of body tissues, it must enter the aorta with high force, so the pressure on the left side of the heart is very high, compared with the right side of the heart, which only needs to send the blood through the lungs. Normally, the high pressure system on the left side is kept separate from the low pressure system on the right by the hearts valves (through which blood can pass only in one direction, if they are working correctly), by the septa (the walls of muscle and connective tissue) that separate the two atrial chambers and the two ventricles, and by whats called low pulmonary vascular resistance (PVR; the vessels maintain a relatively wide diameter for the volume of blood that goes through). However, in pulmonary hypertension, the pressure of the right side of the circulation increases, either because of something happening in the lungs or the heart. Consequently, the World Health Organization (WHO) categorizes pulmonary hypertension into five different types known as groups, which are:

Group 1: Pulmonary arterial hypertension (PAH) this is pulmonary hypertension resulting from pulmonary arterioles narrowing, causing higher than normal resistance to the movement of blood through the entire pulmonary pathway. If the blood cannot move through easily, the pressure increases. This can be caused by certain genetic conditions, by high blood pressure in the liver, by certain infections, notably HIV and schistosomiasis (a parasitic condition that you are unlikely to get, unless you wade in certain rivers, such as the Nile, where the parasite is known to live), certain connective tissue diseases (lupus, scleroderma), and certain congenital conditions. Fairly commonly, PAH is caused by an opening or other connection between the left and right sides of the circulation; due to the persistence of a connection that was present during fetal life that did not close up after birth.

Group 2: This is pulmonary hypertension resulting from acquired or congenital disease of the left heart, including valve disease and dysfunction of the left ventricle.

Group 3: This pulmonary hypertension is due to lung conditions or chronic hypoxia (inadequate oxygen). It includes chronic high altitude conditions, obstructive sleep apnea (you stop breathing momentarily during sleep.)

Group 4: This is pulmonary hypertension due to blood clots in the pulmonary artery or its branches. These can be clots that begin in the lungs, or clots that travel to the lungs from elsewhere, which are called pulmonary emboli (PEs).

Group 5: This is pulmonary hypertension due to various disorders that do not fit into the other four categories. Such disorders include various types of anemia, kidney failure, sarcoidosis (an inflammatory condition), and tumors blocking pulmonary vessels.

How common is pulmonary hypertension during pregnancy?

Pulmonary hypertension is estimated to develop in 178 per 1 million pregnancies.

How is pulmonary hypertension diagnosed?

Pulmonary hypertension is diagnosed based on the measurement of a variety of types of pressure within the pulmonary vessels, especially of a mean pulmonary artery pressure (PAP) of at least 25 mmHg at rest or at least 30 mmHg during exercise. Clinical symptoms, such as dyspnea, fatigue, chest pain, fainting, or near fainting can provide clues. Still, these things often happen during pregnancy without pulmonary hypertension, so the pressure measurements are important. Although there are methods for measuring pressure directly, in a pregnant patient, these methods are generally avoided. Still, echocardiography can reveal enough clues for your doctor to deduce increased pressure leading to a diagnosis.

Does pulmonary hypertension cause problems during pregnancy?

Pulmonary hypertension threatens the life of the mother and fetus and is especially dangerous during pregnancy if it is PAH. If you have pulmonary hypertension already, then pregnancy can exacerbate the condition, due to a blood volume increase during pregnancy of 30-50 percent. During pregnancy, pulmonary hypertension is reported to have a mortality rate as high as 30-56 percent, although mortality is thought to depend greatly on the severity of the condition. Furthermore, the data on the above-cited mortality data were obtained mostly prior to when a drug called prostacyclin became available. Generally, it is recommended that women with PAH do not become pregnant in the first place.

Does pulmonary hypertension cause problems for the baby?

The baby is in danger for the simple fact that the mothers life is in extreme danger. In many cases, especially in a setting of PAH, the doctor may recommend termination of the pregnancy. On the other hand, if it is determined that the mother can endure pregnancy to the point of fetal viability and delivery, cesarean section is recommended.

What to consider about taking medications when you are pregnant:

  • The risks to yourself and your baby if you do not treat the pulmonary hypertension
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know
about using medication to treat my pulmonary hypertension during pregnancy?

The situation is very dangerous, so you are balancing between a bad and a worse situation. Treatment includes parenteral (injected or infused) and/or inhaled prostacyclin. Patients also may receive a type of medication called phosphodiesterase inhibitors. These are considered to be pregnancy safe. If your pulmonary hypertension is mild and determined to be the result of a clot, the doctor may decide to treat with low molecular weight heparin (LMWH), which is thought to be safe for pregnant women. In many cases, however, the treatment may be termination of pregnancy by way of elective abortion.

Who should NOT stop taking medication for pulmonary hypertension during pregnancy?

If you are administered medication, you must not stop taking it, as this is a life-threatening condition.

What should I know about choosing a medication for my pulmonary hypertension during pregnancy?

You may find Pregistrys expert reports about the individual medications to treat pulmonary hypertension here. Additional information can also be found in the sources listed at the end of this report.

What should I know about taking a medication for my pulmonary hypertension when I am breastfeeding?

LMWH does enter breastmilk, but in very tiny amounts and is not harmful because it is degraded in the infants digestive system. LMWH is not taken orally for this reason but must be injected or infused.

What alternative therapies besides medications can I use to treat my pulmonary hypertension during pregnancy?

Treatment depends on the cause of the pulmonary hypertension and the severity. Some causes require surgical correction. Severe cases often require that the pregnancy be terminated. When pregnancy is taken to the point of delivery, cesarean section is the preferred mode of delivery.

What can I do for myself and my baby when I have pulmonary hypertension during pregnancy?

It is very important to comply with your doctors recommendations because pulmonary hypertension can be fatal.

Resources for pulmonary hypertension in pregnancy:

For more information about pulmonary hypertension during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or read the following articles:


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General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

Medications for Pulmonary Hypertension

Read articles about Pulmonary Hypertension