Pulmonary arterial hypertension: what is it and why is it important?

By Cristiano Antonino On May 19, 2023

Pulmonary arterial hypertension refers to a pathological condition characterised by rather high blood pressure within the pulmonary arteries and – consequently – also within the right heart muscle cavities

It is a condition that affects about 60 out of one million people, and can appear indiscriminately at any age, with an almost double incidence in women.

The heart, by its physiological conformation, is composed of two halves, a right and a left one

The right half consists of the right atrium and the underlying right ventricle, the left half consists of the left atrium and the underlying left ventricle.

Each atrium is connected to its corresponding ventricle by a valve.

The cardiac chambers of the right heart, the atria and ventricles, are constantly filled with oxygen-depleted blood from the body via the superior and inferior hollow veins.

The blood from the right atrium passes to the right ventricle, which pumps it to the lungs via the pulmonary arteries.

Often, as a result of causes that will be investigated later, the pulmonary arteries deteriorate and, as they narrow, the blood flow able to circulate within them is also reduced, with a general increase in pressure within the pulmonary arteries themselves and the right side of the heart muscle.

What are the causes and risk factors of pulmonary arterial hypertension?

As mentioned above, pulmonary arterial hypertension occurs when the pulmonary arteries – responsible for the passage of oxygen-deprived blood from the right ventricle to the lungs – undergo an alteration whereby they narrow or close completely, preventing the natural and physiological passage of blood fluid.

This narrowing, known as the “right ventricle”, prevents the right ventricle from functioning properly.

Pulmonary arterial hypertension, depending on the cause that triggers it, can be

Idiopathic pulmonary arterial hypertension

It is so defined when it arises without a clearly identifiable reason.

It is a very rare form, which mostly affects women.

Hereditary pulmonary arterial hypertension

It is so defined when it is caused by a genetic mutation, i.e. passed on by the parents.

The disease in this case is considered a ‘hereditary’ disease.

Pulmonary arterial hypertension induced by drugs or toxic substances

Certain substances, contained in drugs or other toxic substances such as fenfluramine and methamphetamine, are capable of causing vasoconstriction of the pulmonary arteries.

Persistent pulmonary arterial hypertension in the neonate

In cases that are unfortunately not so rare, the newborn child comes into the world with a problem of vasoconstriction in the pulmonary arteries, which is usually the alarm bell of a compromised state of health, e.g. by septicaemia, hypoglycaemia, pulmonary hypoplasia or meconium aspiration syndrome.

Pulmonary arterial hypertension associated with other morbid states

Episodes of pulmonary arterial hypertension have been observed in association with certain morbid states, such as certain connective tissue diseases, such as scleroderma, systemic lupus erythematosus or rheumatoid arthritis; certain congenital malformations of the heart; portal hypertension; HIV infections; thyroid gland disorders; chronic haemolytic anaemia; pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis.

Pulmonary arterial hypertension: how to recognise symptoms

The main symptom experienced by patients with pulmonary arterial hypertension is dyspnoea on exertion.

Whenever they find themselves making even the slightest effort – such as climbing stairs or a brisk walk – they will experience the unpleasant sensation of shortness of breath and excessive fatigue, accompanied in severe cases by a feeling of light-headedness.

The weakness experienced by patients with pulmonary arterial hypertension is due to the tissues not being properly oxygenated and not receiving enough oxygenated blood to perform the required exertion.

Much more rarely, patients complain of coughing, wheezing and hoarseness.

Diagnosing pulmonary arterial hypertension

When a patient begins to experience tiredness, exhaustion and weakness even with minimal exertion, he or she should contact a cardiologist as soon as possible.

During the examination, the cardiologist will first of all take care to take an accurate anamnesis of the patient: knowing his or her lifestyle, habits and personal or family medical history helps enormously in formulating a correct diagnosis.

In order to arrive at an accurate diagnosis, the anamnesis will certainly not be sufficient: it will have to be accompanied by certain diagnostic tests, including the electrocardiogram, echocardiogram and cardiac catheterisation.

The electrocardiogram is a test that can detect and record the heart’s electrical activity and – from the graph released – it will be possible to visualise any abnormalities in the heartbeat that can be traced back to pulmonary arterial hypertension.

With this test, however, it is impossible to detect any thickening of the pulmonary arteries, which is why an echocardiogram (or echocardiography) is used, which can be used to detect any thickening of the pulmonary arteries or the right ventricle, as well as to detect any retrograde flow through the tricuspid valve that separates the right atrium from the right ventricle.

In order to make a definite diagnosis of pulmonary arterial hypertension, however, it will be necessary to perform cardiac catheterisation, a test that consists of inserting a catheter into the right heart intravenously through an arm or leg, so that the blood pressure in the right ventricle and right pulmonary artery can be accurately measured.

Pulmonary arterial hypertension: the most appropriate therapy

For patients diagnosed with pulmonary arterial hypertension, the most appropriate therapy is undoubtedly drug therapy, which must be adequate to treat the causes or pathologies that have triggered or contributed to pulmonary hypertension.

In combination, patients will be given vasodilator drugs – that is, drugs that dilate the blood vessels – to try to reduce the blood pressure within the pulmonary arteries.

Endothelin receptor antagonists, 5-phosphodiesterase inhibitors, guanylate cyclase stimulators or prostacyclin analogues or prostacyclin receptor agonists may then be administered.

These drugs can improve quality of life, prolong life prospects and delay the need for surgical therapy as much as possible.

When a patient is in the appropriate physical condition and his pathology presents with a certain severity, he is likely to be offered surgical therapy, which consists of pulmonary endarterectomy, or even lung transplantation.