Pulmonary hypertension happens when there is high blood pressure in the blood vessels that collect oxygen from the lungs. It is a serious, degenerative condition and it can lead to heart failure and death.
Oxygenated blood is supplied to the rest of the body via the relevant pumping chamber of the heart. If hypertension, or high blood pressure, occurs in this respiratory loop of a person's circulation, it is likely to be a progressive and serious condition.
Pulmonary hypertension is not related to general hypertension. This is a separate condition of systemic high blood pressure, and it affects the wider circulatory system. It is measured using an arm cuff.
General high blood pressure can often be prevented through lifestyle changes, but pulmonary hypertension often has genetic factors.
There are around 200,000 hospitalizations each year in the United States involving pulmonary hypertension, and it is officially responsible for around 15,000 fatalities, although the real figure could be higher. It is most common in people aged 75 or older.
Contents of this article:
What is pulmonary hypertension?
Pulmonary hypertension is a serious, degenerative condition that can lead to heart failure and death.
Pulmonary hypertension is an abnormally raised blood pressure in the pulmonary artery that travels from the right-hand side of the heart to the lungs.
Pulmonary hypertension is diagnosed when the pressure in the pulmonary artery becomes higher than around 40/20 mm Hg or, if the average pressure exceeds 25 mm Hg.
There are two types of raised blood pressure in the lungs: Primary and secondary.
Primary pulmonary hypertension is a relatively rare condition that is not linked to another issue. Secondary pulmonary hypertension stems from an underlying condition, such as a heart defect.
Causes of pulmonary hypertension
Just as the narrowing of a garden hosepipe will increase the pressure of the flow of water and cause water to back up, a similar process occurs with pulmonary hypertension.
The walls of the blood vessels in the lung thicken, narrowing the lumen that blood can travel through. This increases the pressure.
The back pressure on the heart and the increased effort needed to maintain blood flow can give rise to a disease in the heart known as right ventricular hypertrophy.
This is a life-threatening condition, because it can lead to heart failure, the main cause of fatality in people with pulmonary hypertension.
The reason why the blood vessels in the lungs thicken in pulmonary hypertension is complex. Factors include genetics, clotting, inflammation, and changes in metabolism.
Known causes include:
- Problems with connective tissue, such as sclerosis
- Congenital heart defects, which means the defect was present at birth
- Inherited genetic causes, such as a BMPR2 gene mutation
- Use of drugs or other toxins
- HIV infection
- Pulmonary veno-occlusive disease, sometimes associated with cancer or cancer treatment
- Left heart disease, such as heart valve disease
- Lung disease, for example, COPD and chronic high-altitude exposure
- Chronic thrombo-embolic pulmonary hypertension, which occurs after a blood clot has reached the lung.
A range of conditions has been linked to pulmonary hypertension, and the disorder can occur alongside different types of heart or lung disease. A combination of factors may play a role, and sometimes the cause is unknown.
Signs and symptoms of pulmonary hypertension
Syncope and dyspnea are the main symptoms of pulmonary fibrosis.
The main symptom of pulmonary hypertension is shortness of breath, also known as dyspnea.
Two other key symptoms are fatigue, or tiredness, and fainting or dizziness, also known as syncope.
Breathlessness can affect a person's ability to walk. How far someone can walk in 6 minutes is a measure used for testing the effectiveness of drugs for pulmonary hypertension in clinical trials.
The 6-minute walk is also a measure by which pulmonary hypertension can be staged.
Classification of the severity of the condition ranges from class 1, which is pulmonary hypertension without any limits on exercise to class 4, where the patient feels discomfort even at rest.
This staging is used as an indication of the prognosis or outlook of the condition.
It is important to note that pulmonary hypertension can be clinically "silent." In this case, there may be no symptoms at all until the condition becomes severe.
Treatment for pulmonary hypertension
Treatment for pulmonary hypertension depends on the underlying cause, the severity of the condition, and whether the person has other conditions as well.
Therapies that may help to manage the condition include low levels of anaerobic exercise, such as walking, to improve the patient's capacity for physical activity.
Drugs for pulmonary hypertension
A number of different drugs are used to treat pulmonary hypertension, sometimes in combination.
Blood-thinning can help prevent blood clots.
Digoxin is used to treat heart failure. It helps to control heart rate and rhythm, and it increases the amount of blood pumped by each heartbeat.
Blood-thinning drugs, such as warfarin, can help to prevent blood clots, which are more likely in people with hypertension.
Calcium-channel blockers, such as diltiazem, may help some patients.
PDE5 (phosphodiesterase-5) inhibitors increase the blood flow by widening blood vessels. This is called vasodilation. Viagra (sildenafil) is a PDE5 inhibitor. Other vasodilators with other effects are prostanoids, such as epoprostenol.
Endothelin receptor antagonists, such as bosentan and ambrisentan, limit the vasoconstriction that can happen when a person has too much natural peptide.
More invasive treatments, such as transplant surgery, are also possible.
- Atrial septostomy, a procedure to introduce a shunt between heart chambers and improve cardiac output while patients await transplant surgery
- Lung transplant, to replace one or both lungs
- A combined heart and lung transplant.
Some patients with chronic thromboembolic pulmonary hypertension may undergo a procedure called pulmonary thromboendarterectomy (PTE). This is a specialized heart surgery to remove blood clots from coronary arteries.
Continuous oxygen therapy may be necessary to help maintain oxygen saturation in the blood, especially in a patient with lung disease.
During a high-altitude flight, a patient may need oxygen therapy to compensate for reduced oxygen levels.
Other treatments can meet the specific needs of individuals with advanced pulmonary hypertension.