5 March 2021 Author: Ana Rita Rodrigues A pulmonary embolism , also known as pulmonary thromboembolism , is the obstruction of a pulmonary artery by an embolus, preventing the blood flow. This embolus is usually a blood clot or thrombus. However, embolus can also be formed by other substances. This is the case, for example, with emboli of fat, amniotic fluid, bone marrow, fragments of a tumor or air bubbles moving in the bloodstream. When an area of the lung stops receiving blood, a pulmonary infarction can occur, that is, the death of lung tissue. The larger the caliber of the blocked artery, the larger the lung area at risk of heart attack, since larger arteries are responsible for irrigating a larger lung area. When the body can quickly break up clots, the damage is reduced. However, large clots take longer to break down and cause larger lesions. What are the causes of pulmonary embolism? Most pulmonary embolisms are due to blood clots formed in the veins of the legs that then travel in the bloodstream to the pulmonary artery tree where they clog an artery. Sometimes these clots fragment, causing obstruction in more than one smaller artery. More rarely, clots form in the veins of the arms or in the right heart. Clot formation typically occurs when blood circulates slowly, as when someone remains in the same position for a long time. When the person resumes movement, the clot may loosen. Several factors increase the predisposition for blood clots to form in the veins: Extensive and time-consuming surgeries, most frequently during the postoperative period; Prolonged bed rest or inactivity / immobility, for example sitting for a long time; Pelvis or leg fractures; Certain cancers; Venous insufficiency of the legs; Previous history of embolism; Obesity; Cardiac insufficiency; Heart muscle infarction; Use of oral contraceptives; Older age; Hereditary deficiency of a blood clotting inhibitor. What are the symptoms of pulmonary embolism? Small emboli usually do not cause symptoms. When the emboli are larger or multiple and obstruct the blood flow to a large area of the lung, symptoms can vary. The most frequent and important is shortness of breath. Other possible symptoms, usually sudden , are: Acute chest pain, especially during deep breathing; Anxiety and agitation; Increased heart rate; Fainting; Sudden death. The risk of death depends on the size of the embolus, the size and number of obstructed pulmonary arteries and the patient health. When pulmonary infarction (death of lung tissue) occurs, symptoms such as cough, bloody sputum and fever may also appear. These symptoms are usually felt within hours after the onset of the embolism. In people with recurrent episodes of small pulmonary emboli, signs like chronic shortness of breath, swelling of the legs and weakness, tend to develop progressively over weeks, months, or years. Diagnosis The diagnosis is based on symptoms, medical physical exam, and medical tests. Several tests can be ordered, depending on the specifics of the disease and patient, such as: Electrocardiogram; Chest x-ray; Specific laboratory tests such as D-dimers; CT scan with contrast; Eco-Doppler of lower limbs veins; Pulmonary ventilation / perfusion scintigraphy; Pulmonary angiography. Treatment of pulmonary embolism The pharmacological therapy of pulmonary embolism involves anticoagulant drugs, such as heparin, which prevents the volume increase of existing blood clots and the formation of new ones. The medication can be administered subcutaneously or intravenously. Subsequently, other oral anticoagulant drugs are indicated after hospital discharge and sometimes even during hospitalization. Among these drugs are, for example, warfarin, dabigatran, rivaroxaban, apixaban or edoxaban. The medication to be used and the duration of anticoagulant treatment depends on the patient condition and the precipitating cause of the embolism. When the initial clinical condition is more severe and life-threatening , there are two other forms of treatment: Thrombolysis, which is intravenous administration of medicines that dissolve the clot; Surgery to extract the pulmonary artery embolus through a catheter (a thin, flexible tube that runs through the vessels to the embolus). Often, in these more serious situations, cardiovascular and ventilatory support therapy is necessary until definitive treatment. Prevention of pulmonary embolism In people at risk of pulmonary embolism , various measures can be used to prevent the formation of clots in the veins. For patients in the postoperative period, especially those of older age, the use of elastic stockings , leg exercises , and the start of lifting and physical activity as soon as possible is recommended. Heparin ( anticoagulant ) is the most widely used treatment to decrease the likelihood of blood clots forming in patients at risk, such as immobilized people. The dose administered is lower than that used to treat existing embolism. Other anticoagulant drugs such as warfarin, dabigatran, rivaroxaban, apixaban or edoxaban can be used, depending on the specific context. When clot formation is repeated despite all preventive treatments or when anticoagulant drugs cause significant bleeding, a surgery to place a filter lower vena cava can be performed. This will filter the blood coming from the lower body regions, preventing clots of reaching the pulmonary circulation. Meet the cardiology team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
