Pulmonary embolism: causes, symptoms and treatment of blood clot in the lung

Medically reviewed: 15, February 2024

What is pulmonary embolism?

Pulmonary embolism – mechanical obstruction of blood flow in the pulmonary artery due to embolism (thrombus), which is accompanied by a pronounced spasm of the pulmonary artery branches, the development of an acute pulmonary heart, decrease in cardiac output, bronchospasm and decreased blood oxygenation.

Of all the autopsies conducted annually in United States, pulmonary embolism is found in 4-15% of cases. According to statistics, 3% of surgical interventions in the postoperative period are complicated by the development of vascular occlusion in the lungs, while death is observed in 5.5% of cases.

Patients with pulmonary embolism require urgent hospitalization in the intensive care unit.

Pulmonary embolism is predominantly observed in people over 40 years of age.

What are the main causes of Pulmonary embolism?

What causes pulmonary embolism? In 90% of cases, the source of blood clots leading to lung blood clot is located in the basin of the inferior vena cava (ileal-femoral segment, pelvic and prostate veins, deep leg veins).

Risk factors are:

• malignant neoplasms (usually cancer of the lung, stomach and pancreas);
• diseases of the cardiovascular system (myocardial infarction, atrial fibrillation, mitral disease, myocarditis, infective endocarditis);
• heart failure;
• stroke;
• sepsis;
• inflammatory bowel disease;
• erythremia;
• nephrotic syndrome;
• obesity;
• hypodynamia;
• estrogen therapy;
• primary hypercoagulation syndrome;
• antiphospholipid syndrome;
• lack of protein C and S;
• antithrombin III deficiency;
• pregnancy and postpartum period;
• dysfibrinogenemia;
• epilepsy;
• injuries;
• postoperative period.

Pathophysiology of the disease

Depending on the localization of the pathological process, the following types of pulmonary embolism are distinguished:

• embolism of small branches of the pulmonary artery;
• embolism of the lobar or segmental branches of the pulmonary artery;
• massive – the site of localization of a blood clot is the main trunk of the pulmonary artery or one of its main branches.

Depending on the volume of vessels turned off from the bloodstream, four forms of pulmonary embolism are distinguished:

• fatal (the volume of the disabled pulmonary arterial blood flow is over 75%) – leads to a rapid death;
• massive (volume of affected vessels over 50%) – tachycardia, hypotension, loss of consciousness, acute right ventricular failure, pulmonary hypertension, cardiogenic shock may occur;
• submaximal (affects from 30 to 50% of the pulmonary arteries) – characterized by moderate shortness of breath, mild signs of acute right ventricular failure with a normal level of blood pressure;
• small (less than 25% of the blood flow is turned off) – slight dyspnea, no signs of right stomach insufficiency.

Acute massive pulmonary embolism can cause sudden death.

According to the clinical course, a lung blood clot can take the following forms:

1. Fulminant (acute) – occurs when a clot is completely blocked by both main branches or the main trunk of the pulmonary artery. The patient suddenly develops and rapidly increases acute respiratory failure, blood pressure drops sharply, and ventricular fibrillation appears. A few minutes after the onset of the disease, death occurs.
2. Acute – observed with occlusion of the main branches of the pulmonary artery, part of the segmental and lobar branches. The disease begins suddenly. In patients with cardiac, respiratory and cerebral insufficiency arises and progresses rapidly. Lasts 3-5 days, in most cases, complicated by the formation of a pulmonary infarction.
3. Protracted (subacute) – develops with the occlusion of medium and large branches of the pulmonary artery and is characterized by multiple lung infarctions. The pathological process lasts several weeks. The severity of right ventricular and respiratory failure gradually increases. Repeated thromboembolism often occurs, which can be fatal.
4. Recurrent (chronic) – is characterized by repeated thrombosis of the lobar and segmental branches of the pulmonary artery, as a result of which the patient has recurrent pulmonary infarctions and pleurisy, which are usually bilateral. Gradually the right ventricular insufficiency and hypertension of the pulmonary circulation increase. Recurrent lung blood clot usually occurs in the postoperative period, as well as in patients with cardiovascular or oncological diseases.

Classification of the condition

With timely and adequate treatment of pulmonary embolus, the mortality rate does not exceed 10%, without treatment it reaches 30%.

The severity of the clinical picture depends on the following factors:

• the rate of development of blood flow disorders in the pulmonary artery system;
• the size and number of thrombosed arterial vessels;
• the severity of pulmonary blood supply disorders;
• the initial state of the patient, the presence of concomitant pathology.

Pathology manifests itself in a wide clinical range from an asymptomatic course to sudden death. The clinical symptoms of pulmonary embolism are not specific, they are characteristic of many other diseases of the lungs and cardiovascular system.

However, their sudden onset and the inability to explain them with another pathology (pneumonia, myocardial infarction, cardiovascular insufficiency) makes it possible with a high degree of probability to suggest a pulmonary embolism in a patient.

Symptoms of blood clot in lungs (pulmonary embolism)

What are the warning signs of a pulmonary embolism? In the classical clinical picture of pulmonary embolism, several syndromes are distinguished.

Pulmonary and pleural area

Its symptoms are shortness of breath (caused by impaired ventilation and perfusion of the lungs) and cough, which in 20% of patients is accompanied by hemoptysis, pain in the chest (usually in its lower parts). With massive embolism, pronounced cyanosis of the upper half of the body, neck and face develops.

Cardiac

Characterized by a feeling of discomfort and pain behind the sternum, tachycardia, cardiac arrhythmias, severe hypotension until the development of the collaptoid state.

Abdominal

It occurs somewhat less frequently than other syndromes. Patients complain of pain in the upper abdomen, the occurrence of which is associated with stretching the glisson capsule against the background of right ventricular failure or irritation of the diaphragm dome. Other symptoms of abdominal syndrome are vomiting, belching, intestinal paresis.

Cerebral

It is more often observed in elderly people suffering from severe atherosclerosis of the arteries of the brain. It is characterized by loss of consciousness, convulsions, hemiparesis, psychomotor agitation.

Renal

After removing patients from a state of shock, they may develop secretory anuria.

Feverish

Against the background of inflammatory processes in the pleura and lungs, the patient’s body temperature rises to febrile values. The duration of the fever ranges from 2 to 15 days.

Immunological

It develops in the second or third week of the onset of the disease and is characterized by the appearance in the blood of patients circulating immune complexes, the development of eosinophilia, recurrent pleurisy, pulmonitis, and the appearance of a urticoid-like rash on the skin.

According to statistics, 3% of surgical interventions in the postoperative period are complicated by the development of vascular occlusion in the lungs, while death is observed in 5.5% of cases.

Diagnostics of pulmonary embolism

How do you rule out a pulmonary embolism? If a pulmonary embolism is suspected, a laboratory-instrumental examination complex is prescribed, including:

• X-rays of the chest organs – signs of pulmonary embolism are: atelectasis, fullness of the roots of the lungs, symptom of amputation (sudden break of the vessel’s passage), symptom of Westermark (local reduction of pulmonary vascularization);
• Ventilation-perfusion lung scintigraphy — signs of a high probability of pulmonary embolism include: normal ventilation and a decrease in perfusion in one or several segments (the diagnostic value of the method decreases with past pulmonary embolism episodes, lung tumors, and chronic obstructive pulmonary disease);
• Angiopulmonography – a classic method for the diagnosis of pulmonary embolism; the criteria for diagnosis are the detection of the thrombus contour and the sudden break of the branch of the pulmonary artery;
• Electrocardiography (ECG) – allows you to identify indirect signs of pulmonary embolism and eliminate myocardial infarction.

Differential diagnostics is performed with a nonthrombotic embolism of the pulmonary artery (tumor, septic, fatty, amniotic), psychogenic hyperventilation, rib fracture, pneumonia, bronchial asthma, pneumothorax, pericarditis, heart failure, myocardial infarction.

Pulmonary embolism treatment

Patients with pulmonary embolism require urgent hospitalization in the intensive care unit. Drug treatment of pulmonary embolism in the first stage consists in the administration of heparin, indirect anticoagulants and fibrinolytic agents.

Pulmonary embolism is predominantly observed in people over 40 years of age.

In cases of severe hypotension, infusion therapy is performed, dopamine, Dobutamine, Epinephrine hydrochloride are used. In case of a recurrent clinical course of a pulmonary embolus with a long course or for life, indirect anticoagulants, acetylsalicylic acid (Aspirin) are prescribed, a cava filter is installed to prevent clots from entering the inferior vena cava.

The development of heart attack pneumonia is an indication for the administration of broad-spectrum antibiotics.

In case of massive pulmonary embolism and the ineffectiveness of the conducted conservative therapy, surgical intervention is performed in one of two ways:

• closed embolectomy with an aspiration catheter;
• open embolectomy in cardiopulmonary bypass.

Surgical treatment of pulmonary embolism is accompanied by a rather high risk of complications and death.

Possible consequences and complications of pulmonary embolism

Acute massive pulmonary embolism can cause sudden death. In cases where compensatory mechanisms have time to work, the patient does not die immediately, but he quickly increases secondary hemodynamic disorders, which in the absence of timely treatment are fatal. Possible consequences of pulmonary embolism can be:

• acute pulmonary heart;
• pneumonia;
• pleurisy;
• lung abscess;
• gangrene of the lung.

What are the survival rate of a pulmonary embolism?

With timely and adequate treatment of pulmonary embolism, the mortality rate does not exceed 10%, without treatment it reaches 30%. The prognosis is worse in persons with previous heart or lung diseases.

Approximately 1% of patients who have had a pulmonary embolism in the long-term period develop chronic pulmonary hypertension.

Of all the autopsies conducted annually in Russia, pulmonary embolism is found in 4-15% of cases.

How to prevent blood clot in lungs?

In order to prevent pulmonary embolism, preoperative preparation of patients with risk factors include:

• pneumatic compression;
• wearing compression underwear (elastic stockings);
• small doses of heparin.

In the postoperative period, small doses of heparin are injected subcutaneously, and indirect anticoagulants are prescribed.

In case of recurrent pulmonary embolism, indirect anticoagulants are prescribed for life, deciding on the installation of a cava filter.