What is Pulmonary Arterial Hypertension?
Arterial pulmonary hypertension is a pathological condition characterized by a persistent increase in systolic, diastolic and mean pulmonary artery pressure. This condition can occur for no apparent reason, that is, be primary, or is a consequence of other diseases of the lungs, heart, vessels, etc.
Primary pulmonary hypertension is one of the rare diseases, and before the widespread use of cardiac catheterization, the diagnosis was most often made by pathologists. Intravital diagnosis became possible in connection with the introduction into the clinical practice of cardiac catheterization, pulmonary artery and angiocardiography.
According to various experts, primary pulmonary hypertension occurs with a frequency of 0.17 to 1%. There is a predominant defeat of women, especially in younger age groups. There is an indication of a family predisposition. In modern literature, primary pulmonary hypertension is referred to as essential or idiopathic pulmonary hypertension, primary pulmonary arterial sclerosis, right ventricular idiopathic hypertrophy, black heart disease, Ayerza’s disease, etc. There is still no single point of view on the etiology and pathogenesis of primary pulmonary hypertension.
What Causes Pulmonary Arterial Hypertension?
Most specialists consider the cause of the development of primary pulmonary hypertension a sharp hypertrophy of the muscle layer of the pulmonary arterioles, confirming this by an increase in the total muscle mass of the middle layer of the arterial wall, as well as some decrease in pulmonary arterial pressure and resistance due to the introduction of vasodilating agents into the pulmonary artery system. Some point to hypoxia as the cause of the onset of primary pulmonary hypertension, because it is the most potent of the known vasoconstrictors.
What Happens During Arterial Pulmonary Hypertension?
The narrowing of the vessels can be caused by the influence of other environmental factors, for example, the intake of medications, the nature of nutrition or some other, currently unknown factors. Recurrent pulmonary embolism may be a cause of pulmonary hypertension, although in this case pulmonary hypertension can hardly be considered primary, and morphological changes in the re-embolization of the pulmonary artery and primary pulmonary hypertension are not identical.
Some specialists believe that primary pulmonary hypertension can arise as a result of thrombosis of small branches of the pulmonary artery on the basis of a general increase in blood clotting, which develops as a result of impaired platelet function, fibrinolysis or other coagulopathies. However, all these possibilities now remain purely conjectural.
Morphologically, two main types of primary pulmonary hypertension are distinguished:
- with primary lesion of pulmonary arterioles
- and with predominant lesion of small pulmonary veins.
In the first case, a thickening of the middle membrane of the pulmonary artery “of the muscle type” is revealed, local arterioles expand, and in some cases necrosis arteritis in the walls of the pulmonary arteries of the muscle type.
With a predominant lesion of the pulmonary veins, which is rare, there is loose basophilic cellular fibrosis leading to a widespread obliteration of the pulmonary veins and venules. Almost in all cases, thrombi, fresh or in the process of organization, are the basis of fibrosis of the intima of the pulmonary veins. The same blood clots occur in the pulmonary arteries and arterioles. Usually, the damage to the arteries is limited to a different degree of hypertrophy of the middle shell, which, apparently, develops again, as a result of increased postcapillary pressure.
There are two forms of primary pulmonary hypertension: congenital and acquired. With congenital form, the resistance of small vessels remains the same as in the intrauterine period of development, with acquired – the pressure can begin to increase at any age, reaching very high figures.
Symptoms of arterial pulmonary hypertension
Early stages of pulmonary hypertension are usually not diagnosed. Patients almost never consult a doctor before the appearance of severe symptoms of the disease. The most typical symptom of primary pulmonary hypertension is shortness of breath, accompanied by a sensation of suffocation, expressed even with a slight physical exertion. A frequent symptom is fast fatigue, sometimes chest pain and palpitations.
Objective symptoms of primary pulmonary hypertension are divided into 2 groups:
- signs of hypertrophy of the right ventricle;
- signs of pulmonary hypertension.
Signs of hypertrophy of the right ventricle are manifested:
- systolic pulsation of the enlarged right ventricle in the epigastric region;
- an extension of the border of cardiac dullness due to the right ventricle.
Signs of pulmonary hypertension are characterized by:
- accent tone II or – more importantly – accent tone II in combination with its splitting over the pulmonary artery;
- percussion dilatation of the pulmonary artery;
- diastolic murmur over the pulmonary artery due to the relative insufficiency of the valves of the pulmonary artery.