What is pulmonary arterial hypertension and how is it treated?

Pulmonary arterial hypertension (PAH) is a group of diseases characterized by elevated pulmonary artery tension. Gradually progressive pathology is dangerous with complications such as heart failure and death. PH in the initial stages is not manifested in any symptoms in the majority of cases. Thus, in 80% of cases, the disease is diagnosed only after the symptoms and damage have become critical.

Short information about pulmonary arterial hypertension

PAH develops as the gradual closure of the lumen of the average and small lungs vessels resulting in the raised tension in them and deterioration of the pumping function of the heart.

The main complaints in PAH are fatigue, weakness, shortness of breath in physical activity, discomfort in the left side of the chest, less often compressive chest pain during exercise, fainting. The clinical manifestations of the insufficient pumping heart function: swelling of the legs and fluid in the abdominal cavity.

The disease is divided into several groups by the presumable cause and age of the onset of the symptoms. The correct determination of the disease group is crucial for effective treatment.

Causes of PAH:

- Heredity;
- HIV;
- Left ventricle dysfunction;
- Valvular defects;
- COPD or other lung diseases;
- Breathing disorders during sleep, and others.

Based on the severity of clinical manifestations, 4 classes of PAH are distinguished:

- The first functional class includes patients whose physical abilities suffer during high physical exertion.
- The second class includes patients who feel comfortable at rest, but moderate exercise leads to shortness of breath, weakness, chest pain, or dizziness.
- The third functional class includes patients, in whom even household loads can cause the appearance of the above complaints.
- Patients with the fourth grade of PAH are unable to perform any physical activity, and even at rest, they may have weakness and shortness of breath.

If the above clinical symptoms appear, the patient should immediately consult a doctor.

To better understand what research and tests are needed to diagnose the disease, we would like to discuss the mechanism of the disease occurrence.

- One of the major causes of PAH is COPD and chronic bronchitis that develop in 90% of tobacco smokers.
- Repeated thromboembolism in the pulmonary vessels often promotes to the onset of PAH.
- PH is the most common complication of heart muscle damage in ischemic heart disease, inflammatory myocardial diseases and heart defects.
-  PAH is main complication and cause of death in people with congenital heart defects who are denied surgical treatment. But it can also develop in people who have previously been operated for congenital heart defects.
- PAH often occurs in autoimmune pathologies such as systemic lupus, systemic scleroderma, and rheumatoid arthritis.
- In addition, lung vessel pressure raise can develop in HIV and hematological diseases.

In the case when the examination does not find reasons for PAH development, idiopathic PAH is diagnosed. This name originated from two Greek words: idios and pathos - "a kind of suffering." Idiopathic PAH is an independent disease, in contrast to secondary PAH occurring as a aggravation of various diseases of the circulatory and respiratory organs. Idiopathic PAH was first mentioned in 1901 by Argentine physicians.

In 1967 - 1970 In Europe, there was a substantial rise in the frequency of PAH related to the widespread use of medicines for obesity.

A similar situation developed in Spain in 1981, when against the background of the use of rapeseed oil, an epidemic of toxic complications developed, clinically manifested by muscle damage. PAH was diagnosed in 2.5% of 20,000 cases. Later it was proved that the occurrence of this disease is related to the certain substance contained in rapeseed oil.

According to statistics, young women, aged 20 to 40, are most susceptible to idiopathic PAH. The disease in men is much less common. On average, idiopathic PAH occurs in only 2 people per million population. The precise reasons for the disease occurence are unknown. Considerable attention has been paid to the study of this issue in recent years. Presumable risk factors include weight loss medicines (some of the groups), amphetamines, cocaine, tryptophan, hormonal contraceptives, smoking, and even pregnancy. An opinion is expressed about the role of genetic factors in the onset of this disease.

PAH diagnosis

The diagnosis is made if the pressure in the lung artery is more than 25 mm Hg at rest during catheterization of the right chambers of the heart and manometry. The main non-invasive method for diagnosing PH is echocardiography. To diagnose PAH associated with lung pathology, the patient additionally needs to undergo bodyplethysmography or, in extreme cases, spirography. Multispiral computed tomography of the lungs in the vascular mode is a mandatory study that allows not only to confirm PAH, but also to establish its cause: thromboembolic disease or lung pathology. And only in the case of low information content of computed tomography of the lungs is it justified to carry out angiopulmonography. An obligatory method for diagnosing PAH is such an invasive method as catheterization of the right chambers of the heart, which is performed only in specialized centers.

Treatment of PAH

Treatment of PAH is a difficult task. Therefore, specialized centers for therapy of this pathology have been created all over the world. Today, new groups of drugs have appeared in the arsenal of doctors, which were not previously used in the treatment of this pathology. Among these drugs are endothelin receptor antagonists, type PDE5 inhibitors (Sildenafil) and synthetic prostacyclin analogs, which not only improve the quality of life of patients but also significantly increase its duration.

Some doctors assume that lung transplant can solve the problem. But research shows that the results of lung transplantation in patients with idiopathic PAH are worse than in patients with lung pathology. Thus, the survival rate of patients with idiopathic PAH within 1 year after transplantation is 70% and 50-60% within 3 years. Therefore, this treatment method should be considered as an alternative method in cases of low efficacy of drug therapy. In recent years, the method of surgical removal of a thrombus has been actively used in the therapy of people with thrombosis and thromboembolism of the pulmonary artery. However, the long-term results of this method depend on the severity of PAH at the time of the operation. Therefore, drug treatment using the entire arsenal of medicines can be used as a "bridge" in preparing patients for surgery.

Post by: Emma Ager, MD, Copenhagen, Denmark