The pulmonary arteries play a key role: they carry blood from the right ventricle of the heart to the pulmonary lobes, where it is oxygenated. Following a phlebitis, it happens that a blood clot goes up towards this artery and the mouth: it is the pulmonary embolism.

The pulmonary artery starts from the right ventricle of the heart. It then rises next to the aorta, and arriving below the arch of the aorta, divides into two branches: the right pulmonary artery which goes towards the right lung, and the left pulmonary artery towards the left lung.

At the level of the hilum of each lung, the pulmonary arteries again divide into so-called lobar arteries:

• in three branches for the right pulmonary artery;
• in two branches for the left pulmonary artery.

These branches in turn subdivide into smaller and smaller branches, until they become the capillaries of the pulmonary lobule.

Pulmonary arteries are large arteries. The initial part of the pulmonary artery, or trunk, measures approximately 5 cm by 3,5 cm in diameter. The right pulmonary artery is 5 to 6 cm long, against 3 cm for the left pulmonary artery.

The role of the pulmonary artery is to bring the blood ejected from the right ventricle of the heart to the lungs. This so-called venous blood, that is to say non-oxygenated, is then oxygenated in the lungs.

Pulmonary embolism

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are the two clinical manifestations of the same entity, venous thromboembolic disease (VTE).

Pulmonary embolism refers to the obstruction of a pulmonary artery by a blood clot formed during phlebitis or venous thrombosis, most often in the legs. This clot breaks off, travels up to the heart through the bloodstream, then is ejected from the right ventricle to one of the pulmonary arteries that it ends up obstructing. The part of the lung is then no longer well oxygenated. The clot causes the right heart to pump harder, which can cause the right ventricle to widen.

Pulmonary embolism manifests itself in various more or less acute symptoms depending on its severity: chest pain on one side increasing on inspiration, difficulty in breathing, sometimes cough with sputum with blood, and in the most severe cases, low cardiac output, arterial hypotension and state of shock, even cardio-circulatory arrest.

Pulmonary arterial hypertension (or PAH)

A rare disease, pulmonary arterial hypertension (PAH) is characterized by abnormally high blood pressure in the small pulmonary arteries, due to a thickening of the lining of the pulmonary arteries. To compensate for the reduced blood flow, the right ventricle of the heart must then exert an extra effort. When it is no longer successful, respiratory discomfort on exertion appears. At an advanced stage, the patient may develop heart failure.

This disease can occur sporadically (idiopathic PAH), in a family context (familial PAH) or complicate the course of certain pathologies (congenital heart disease, portal hypertension, HIV infection).

Chronic thromboembolic pulmonary hypertension (HTPTEC)

It is a rare form of pulmonary hypertension, which can occur as a result of unresolved pulmonary embolism. Due to the clot that clogs the pulmonary artery, blood flow is reduced, which increases blood pressure in the artery. HPPTEC is manifested by different symptoms, which can appear between 6 months and 2 years after pulmonary embolism: shortness of breath, fainting, edema in the limbs, cough with bloody sputum, fatigue, chest pain.

Treatment of pulmonary embolism

The management of pulmonary embolism depends on its level of severity. Anticoagulant therapy is usually sufficient for mild pulmonary embolism. It is based on the injection of heparin for ten days, then the intake of direct oral anticoagulants. In case of high-risk pulmonary embolism (shock and / or hypotention), an injection of heparin is performed together with thrombolysis (intravenous injection of a drug that will dissolve the clot) or, if the latter is contraindicated , a surgical pulmonary embolectomy, to quickly reperfuse the lungs.

Treatment of pulmonary arterial hypertension

Despite therapeutic advances, there is no cure for PAH. The multidisciplinary care is coordinated by one of the 22 competence centers recognized for the management of this disease in France. It is based on various treatments (in particular continuous intravenous), therapeutic education and adaptation of lifestyle.

Treatment of chronic thromboembolic pulmonary hypertension

Surgical pulmonary endarterectomy is performed. This intervention aims to remove the fibrotic thrombotic material obstructing the pulmonary arteries. Anticoagulant treatment is also prescribed, most often for life.

The diagnosis of pulmonary embolism is based on a complete clinical examination looking, in particular, for signs of phlebitis, signs in favor of severe pulmonary embolism (low systolic blood pressure and accelerated heart rate). Various examinations are then carried out according to the clinical examination to confirm the diagnosis and assess the severity of the pulmonary embolism if necessary: ​​a blood test for D-dimers (their presence suggests the presence of a clot, arterial blood gas. CT angiography of the lungs is the gold standard for detecting arterial thrombosis. impact on the functioning of the lungs, an ultrasound of the lower limbs to look for phlebitis.

In case of suspicion of pulmonary hypertension, a cardiac ultrasound is performed in order to highlight the rise in pulmonary arterial pressure and certain cardiac abnormalities. Coupled with Doppler, it provides visualization of blood circulation. Cardiac catheterization can confirm the diagnosis. Performed using a long catheter introduced into a vein and going up to the heart and then to the pulmonary arteries, it makes it possible to measure the blood pressure at the level of the cardiac atria, the pulmonary arterial pressure and the blood flow.

Chronic pulmonary thromboembolic hypertension is sometimes difficult to diagnose because of its inconsistent symptoms. Its diagnosis is based on various examinations: echocardiography to begin with then pulmonary scintigraphy and finally a right cardiac catheterization and pulmonary angiography.