Pulmonary Hypertension
What is pulmonary hypertension and what causes it?
The term pulmonary hypertension is a collective term for diseases characterized by an increase in vascular resistance and thus blood pressure in the pulmonary circulation. The pulmonary circulation refers to the part of the blood circulation that transports blood from the heart to the lungs and back. Pulmonary hypertension often results in right heart failure - an insufficient pumping capacity of the right ventricle. Pulmonary hypertension can be classified into primary and secondary forms. This classification is simplified.
Primary pulmonary hypertension is considered idiopathic: The cause of the disease cannot be determined. There is no underlying pathomechanism (or it is unknown), which is why the symptom (pulmonary hypertension) itself represents the disease. However, this form of pulmonary hypertension is very rare. Various possible causes are discussed - including an increased release of vasoconstricting factors and a decreased production of relaxing factors. However, the cause is not sufficiently researched.
Significantly more common is the secondary form of pulmonary hypertension. This occurs when pulmonary hypertension arises in the context of or as a consequence of an underlying disease. In this form, it is therefore sensible to treat the underlying disease and thereby alleviate or cure the pulmonary hypertension. Common underlying diseases in secondary pulmonary hypertension include chronic obstructive pulmonary disease (COPD), pulmonary embolism, pulmonary fibrosis, sarcoidosis, AIDS, adult respiratory distress syndrome (ARDS), sickle cell anemia, scleroderma, or congenital heart defects.
In contrast, chronic pulmonary hypertension is not based on a "physically controlled" narrowing of the pulmonary vessels, but rather a remodeling of these vessels. The extent of the vascular musculature increases, and over time it is transformed into connective tissue. The flexibility of the pulmonary vessels decreases. This condition is irreversible. Additionally, there is sclerosis of the pulmonary vessels, which leads to further deterioration of the condition. The ventilation of the lungs does not function optimally as the disease progresses. A load-dependent adjustment is also no longer possible. This leads to a progressive decrease in oxygen uptake. The previously mentioned heart failure develops as a result of the increased pulmonary arterial resistance: The cardiac output continuously decreases.
Symptoms of Pulmonary Hypertension
The physical performance of patients affected by pulmonary hypertension is severely limited. Typical symptoms of pulmonary hypertension include dyspnea (shortness of breath). In 60 to 100 percent of patients, exertional dyspnea occurs - that is, shortness of breath during exertion. Coughing and a "reduced general condition" are also typical symptoms of pulmonary hypertension. A "reduced general condition" refers to a generally poor physical state that limits daily activities. Other common symptoms and signs include circulatory disturbances up to "circulatory collapse" (syncope), angina pectoris ("chest tightness"), fatigue, peripheral edema, cyanosis of the skin and/or mucous membranes (cyanosis), clubbing fingers (digitus hippocraticus), and Raynaud's syndrome.
The mean pressure in the pulmonary artery (pulmonary artery) in healthy individuals is 12 to 16 mmHg. Latent pulmonary hypertension is present from a pulmonary pressure of 21 to 24 mmHg at rest. Manifest pulmonary hypertension is present when the pulmonary pressure at rest is more than 25 mmHg. Initial symptoms are felt from a mean pressure in the pulmonary artery of about 30 to 40 mmHg. The symptoms typically become more pronounced under exertion. From 50 to 70 mmHg, the cardiac output then continuously decreases due to the increased pulmonary arterial resistance. The right heart load increases. If left untreated, this usually leads to right heart failure and death from heart failure. Tricuspid valve insufficiency usually occurs with pulmonary hypertension.
How is pulmonary hypertension diagnosed and treated?
Diagnostically, a chest X-ray is usually performed. An echocardiogram (ultrasound examination of the heart) with an indirect measurement of pulmonary artery pressure, a cardiac catheterization (direct measurement of pulmonary artery pressure), and a lung biopsy (if secondary pulmonary hypertension is suspected) are also part of the diagnostics for suspected pulmonary hypertension. Laboratory diagnostics can gather evidence of any existing secondary heart failure.
Regarding the treatment of the disease, it should be noted that any underlying disease should be treated in such a way that it does not lead to the chronicization of pulmonary hypertension. If chronic pulmonary hypertension occurs, no curative treatment is possible anymore. The treatment can then only be palliative. This palliative treatment is carried out medically or, under certain circumstances, through transplantation - either of the lung alone or of both the heart and lungs. The medical treatment usually consists of administering calcium antagonists, prostacyclin derivatives (intravenously, subcutaneously, or inhaled), endothelin receptor antagonists, and PDE5 inhibitors. In cases of right heart strain, the administration of diuretics and digitalis preparations is also indicated. To alleviate symptoms and improve quality of life, long-term oxygen therapy is often performed.
Pulmonary hypertension is divided into four stages. The prognosis is usually poor. If left untreated, the average life expectancy from the time of diagnosis is less than three years. With a mean pulmonary artery pressure of over 30 mmHg, the 5-year survival rate is about 30 percent. If the mean pulmonary artery pressure exceeds 50 mmHg, the 5-year survival rate is around 10 percent.
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By Sabine Croci.
This article is medically reviewed. Last updated (12/2023).
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