Thromboembolism of pulmonary arteries

THROMBOEMBOLY OF PULMONARY ARTERIES - acute blockage of the pulmonary trunk or branches of the arterial system of the lungs by a thrombus formed in the veins of the great circle of blood circulation or in the right half of the heart. It is always a complication of any disease or pathological condition that causes an increase in the activity of the blood coagulation system and thrombus formation in the venous system. Most often embologogenic thromboses are localized in the trunk veins of the lower extremities, the pelvic veins and the inferior vena cava (see Thrombosis). Very dangerous are the so-called floating thrombi of the ileoccava segment, loosely fixed to the wall of the vessel. Thromboembolism from the right heart is more rarely observed in rheumatic malformations, atrial fibrillation, bacterial septic endocarditis. Factors predisposing to thromboembolism of the pulmonary arteries are operations on the pelvic organs and lower extremities, especially in the elderly; Injuries of the lower limbs; Prolonged catheterization of the main veins (large saphenous vein of the thigh, subclavian, etc.); Prolonged bed rest; Heart failure and heart rhythm disturbances; Varicose veins of the lower extremities, poetrombophlebitic syndrome, etc.

There are thromboembolism of the trunk and main branches of the pulmonary artery (massive pulmonary embolism), thromboembolism of the lobar and segmental branches and thromboembolism of the small branches of the pulmonary arteries. When the large arteries are clogged, the volume of the vascular bed of the lungs decreases, pulmonary hypertension develops and acute right ventricular failure develops, or cardiac arrest occurs (with pulmonary embolism). Almost in 10% of patients as a result of ischemia of the pulmonary tissue, a lung infarct is formed with the outcome of an infarct pneumonia in case of infection.

Clinical picture . The first symptoms of thromboembolism often appear when straining, coughing, rapid change in body position. Characterized by an acute onset: sudden shortness of breath , not associated with physical exertion, acute pain in the chest , fear of death with motor anxiety of the patient. Then, there is often a dry irritating cough , hemoptysis (in 1/3 of the patients more often on the 2nd -3th day), acrocyanosis, less often cyanosis , especially the upper half of the trunk: the body temperature rises (from subfebrile to hectic for several hours or days). Depending on the prevailing symptoms, several variants of the clinical course of thromboembolism are distinguished. Lightning-fast form leads to sudden death; Is observed with thromboembolism of the pulmonary trunk. The syndrome of acute respiratory failure manifests itself with severe dyspnea with a respiratory rate of 30-60 in 1 min, cyanosis, changes in the lungs imitating the picture of the bronchopulmonary system (obstructive bronchitis, croupous pneumonia, spontaneous pneumothorax, exudative pleurisy). A number of patients develop acute bronchial obstruction syndrome and even asthmatic status, resistant to treatment with antiasthmatics. At the same time, with thromboembolism of large branches of the pulmonary arteries, the only complaint of the patient may be shortness of breath with meager auscultatory symptoms. The syndrome of the acute pulmonary heart is characterized by a sudden onset of tachycardia, the fall of the blood pressure up to the development of collapse, the rapid expansion of the heart's borders to the right, the appearance of the rhythm of the gallop, systolic murmur and the accent of the second tone over the pulmonary trunk, sometimes systolic murmur at the base of the xiphoid process, acrocyanosis, swelling of the cervical veins. Abdominal syndrome is characterized by acute pain in the right upper quadrant, paresis of the intestine, pseudo-positive symptoms of Shchetkin-Blumberg, Ortner, vomiting , persistent hiccough . The syndrome of acute coronary insufficiency develops as a result of reflex spasm of the coronary arteries of the heart and proceeds according to the type of angina attack with signs of myocardial ischemia on the ECG. Cerebral syndrome is characterized by short-term obscuration or loss of consciousness, sudden muscle weakness, sometimes clonic convulsions, the appearance of focal neurological symptoms and signs of cerebral edema.

The diagnosis of thromboembolism can be suspected on the basis of a clinical picture (sudden occurrence of cardiorespiratory disorders in a patient with risk factors for thromboembolism); Electrocardiographic signs of acute pulmonary heart (high pointed P tooth in leads II, III, AVF, deep tooth S in I standard lead, deep Q tooth in III lead, incomplete blockage of right bundle right arm); X-ray signs (high standing of the dome of the diaphragm, discoid atelectasis, plethora of one of the roots of the lungs or "chopped off" root, infiltrate or pleural effusion). To confirm the diagnosis, perfusion lung scintigraphy is used, which allows to reveal triangular areas of pulmonary perfusion reduction, as well as angiopulmonography.

Treatment . Emergency therapy begins with administering to the patient parenterally 1 ml of a 2% solution of promedol or 1% morphine solution (with tachypnea, chest pain, right hypochondrium, hemoptysis) and 10,000-15,000 units of heparin. After this, the patient is urgently hospitalized, ensuring during transportation the maximum rest, inhalation of oxygen. In a hospital, thrombolytic therapy with streptokinase, urokinase is carried out, agents that prevent platelet aggregation (rheopolyglucin, acetylsalicylic acid, xanthinal nicotinate , ticlid, etc.) are prescribed. Surgical treatment is embobectomy (removal of the embolus from the pulmonary artery). The operation is carried out according to vital indications.

Forecast . The massive thromboembolism of the pulmonary arteries is fatal. Subacute flow (often up to several weeks) is noted with thromboembolism of the lobar or segmental arteries and with timely initiated treatment may result in recovery. Prognostically unfavorable are persistent lowering of blood pressure, acute violations of the heart rhythm, severe right ventricular failure and progressive diffuse cyanosis . With recurrent course, which is typical mainly of thromboembolism of small arterial branches, repeated development of lung infarctions and gradual formation of chronic pulmonary heart are observed.

Prevention of thromboembolism of pulmonary arteries is to prevent and timely treatment of phlebotrombosis and thrombophlebitis with an increased risk of their development (in particular, in pregnant women, patients with venous stasis). Patients in preoperative and early postoperative periods, as well as persons forced to stay in strict bed rest for a long time, are treated with antiaggregants. Surgical prophylaxis consists in timely phlebectomy in patients with varicose veins of the lower extremities and partial occlusion of the main veins (plication of the inferior vena cava, installation of an umbrella cava filter) to delay the migrating thrombus with a high risk of thrombosis in the inferior vena cava system.