Pulmonary Embolism

Pulmonary infarction, pulmonary embolism, pulmonary embolism; pulmonary artery embolism, lung

Causes of a pulmonary embolism

A pulmonary embolism is caused by a thrombus (a coagulum of blood components), which is usually infiltrated into the pulmonary vessels from the large circulation of the body and moves them. The risk of developing a thrombus is not the same for all individuals – as with many other diseases, there are special risk factors and protective factors that promote or prevent the development of a thrombus. A large proportion of the thrombi that cause pulmonary embolism originate in the deep veins of the legs.

This is where thrombi form, for example during long periods of inactivity (see: Thrombosis in the leg). The fact that someone does not move for a long period of time can occur in the course of an accident, in which there are fractures and injuries in and on the legs, which mean that the patient has to lie in bed for a long time. A further risk factor lies in prostheses on knees, hips and other joints, since damage to vessels cannot be avoided here either.

Thrombi can more easily form at the damage. In addition, patients are often unable to move fully after prostheses – therefore one of the goals of surgery is to get operated patients on their feet as quickly as possible in order to minimize the time they spend in bed and thus the risk of thrombus formation. In addition to operations on the joints, the risk is generally increased after operations of any kind.

Another group of risk factors are genetic pathologies (unnatural expressions of genes), e.g. the factor V Leiden mutation. There is also an increased risk of pulmonary embolism during pregnancy. Young girls and women who use contraceptive pills also have a higher risk of developing thrombosis and thus pulmonary embolism.

If there are other hormonal or metabolic disorders, it should be noted that this also promotes the formation of thrombus. Smoking and obesity as risk factors for pulmonary embolism should not be disregarded. Another very relevant risk factor is immobilization of the legs during long journeys.

The problem here is that the blood no longer circulates properly and therefore accumulates in the legs (stasis). If you know that you are planning a long journey (e.g. air travel), it is advisable, especially for patients with other risk factors (as described above), to have a one-time heparin injection given by your family doctor. This will reduce blood clotting over the following days and thus the risk of developing a thrombus.

If there are known cases of thrombosis and pulmonary embolism in the family, a doctor should be consulted to determine the extent to which the patient himself has any risk factors and whether prophylactic measures need to be taken. If there are other disturbances in the hormonal or metabolic balance, then it must be noted that the formation of thrombus is also favored here. Smoking and obesity as risk factors for pulmonary embolism should not be disregarded.

Another very relevant risk factor is immobilization of the legs during long journeys. The problem here is that the blood no longer circulates properly and therefore accumulates in the legs (stasis). If you know that you are planning a long journey (e.g. air travel), it is advisable, especially for patients with other risk factors (as described above), to have a one-time heparin injection given by your family doctor.

This will reduce blood clotting over the following days and thus the risk of developing a thrombus. If there are known cases of thrombosis and pulmonary embolism in the family, a doctor should be consulted to determine the extent to which the patient himself has any risk factors and whether prophylactic measures need to be taken. The starting point of a pulmonary embolism is in most cases a thrombosis of the lower leg vein thrombosis (leg vein thrombosis, approx.

60%) or pelvic vein thrombosis (approx. 30%). In the early phase of thrombosis development, a thrombus is unstable and can tear away from the vein wall.

This torn off piece, which is medically called an embolus, now floats back to the heart via the bloodstream and from there is pumped into the lungs. There the vessels constrict again and the embolus blocks the vessel and the pulmonary bloodstream behind it. According to current opinion, flying increases the risk of leg vein thrombosis and pulmonary embolism.

The reason for this is, on the one hand, the longer sitting position, and on the other hand, the lower air pressure slightly increases blood clotting.The longer the flight, the higher the risk of developing thrombosis. Especially people with multiple pre-existing conditions and thus an increased risk of thrombosis should take care to stand up regularly during flights and to activate the leg muscles through various exercises. Compression stockings and compression bandages also greatly reduce the risk of leg vein thrombosis and pulmonary embolism during flights.

Surgery increases the risk of deep vein thrombosis and pulmonary embolism. The risk of this depends mainly on the length of the operation and the subsequent restriction of movement. To reduce the risk, heparin is usually given before and after an operation in the form of infusions or abdominal injections.

After short operations without subsequent restriction of movement, pulmonary embolisms are rare. After major operations and a ban on getting out of bed after the operation, leg vein thromboses and pulmonary embolisms are relatively common despite the administration of heparin. As a rule, however, a serious pulmonary embolism is diagnosed and treated in good time by staying in the clinic and good monitoring, so that secondary damage is rare.

Chemotherapy can increase the risk of pulmonary embolism and leg vein thrombosis by increasing the tendency of the blood to form thromboses. However, this depends strongly on the medication used. For example, chemotherapy containing lenalidomide or thalidomide usually increases the risk significantly and should therefore always be accompanied by therapy with heparin.

Other drugs, however, have little or no effect on the risk of thrombosis. It should be remembered that the underlying cancer usually also increases the risk of pulmonary embolism and that, accordingly, the chemotherapeutic agent need not be the cause of pulmonary embolism. Those who use the pill for contraception should know that most pills increase the risk of thrombosis and thus the risk of pulmonary embolism.

The active ingredients used in pills are estrogens and progestins. Combination preparations are most frequently prescribed in Germany. The risk of thrombosis varies from one drug to another, depending on the dose of the active ingredients used and the progestin contained in the pill.

Combined preparations with a high estrogen dose and progestins of the 3rd or 4th generation increase the risk up to 5 times, while progestin-only preparations have little effect on the risk of thrombosis. In combination with other risk factors such as smoking, the risk of thrombosis can increase even more. Smoking not only increases the risk of various lung diseases, but also significantly increases the risk of thrombosis.

This also significantly increases the probability of pulmonary embolism in smokers. The reason for this is that smoking alters the composition of the blood and its flow properties and causes vascular damage. In particular, taking the pill at the same time significantly increases the risk of pulmonary embolism and leg vein thrombosis, which is why one of the two must be avoided.

If you stop smoking, the risk of thrombosis returns to normal after weeks or months. Since the cause of a pulmonary embolism is in most cases a thrombosis in the leg (rarely air, fat or foreign bodies), the risk factors for pulmonary embolism and thrombosis apply equally:

Operations (especially artificial hip joint and artificial knee joint)
Overweight
Smoking
Gender (Women > Men)
Lack of exercise (long-distance flights= economy class syndrome))
Birth
Varicose veins (varicosis)
Blood diseases (leukemia)
Heart diseases (especially atrial fibrillation)
Drugs (especially oral contraceptives (“pill”))
Tumor diseases (e.g. prostate cancer or pancreatic cancer)
Hereditary diseasesAPC resistance (“factor V Leiden mutation”) is the most common hereditary disease associated with a risk of thrombosis. The risk of thrombosis is 7 – 100 times higher (depending on heredity).
Antithrombin III deficiency (AT III) mainly affects younger patientsProtein C and Protein S deficiency*If these anticoagulant factors are reduced by a congenital deficiency, thrombosis can already occur in adolescence. Hyperhomocysteinemia is an inherited disordered ability to break down homocysteine with greatly increased homocysteine levels in the blood. The consequences include an increased risk of thrombosis.

All the above-mentioned hereditary diseases can be diagnosed by blood tests.
APC resistance (“factor V Leiden mutation”) is the most common hereditary disease associated with a risk of thrombosis. The risk of thrombosis is 7 – 100 times higher (depending on heredity).
Antithrombin III deficiency (AT III) predominantly affects younger patients
Protein C and Protein S – deficiency*If these anticoagulant factors are reduced by a congenital deficiency, thromboses can already occur in adolescence.
Hyperhomocysteinemia is an inherited disordered breakdown of homocysteine with greatly increased homocysteine levels in the blood. The consequences include an increased risk of thrombosis.
All the above-mentioned hereditary diseases can be diagnosed by blood tests.
Liver diseases with disturbed formation of coagulation factors (e.g. liver cirrhosis)
APC resistance (“factor V Leiden mutation”) is the most common hereditary disease associated with a risk of thrombosis. The risk of thrombosis is 7 – 100 times higher (depending on heredity).
Antithrombin III deficiency (AT III) predominantly affects younger patients
Protein C and Protein S – deficiency*If these anticoagulant factors are reduced by a congenital deficiency, thromboses can already occur in adolescence.
Hyperhomocysteinemia is an inherited disordered breakdown of homocysteine with greatly increased homocysteine levels in the blood. The consequences include an increased risk of thrombosis.
All the above-mentioned hereditary diseases can be diagnosed by blood tests.

A pulmonary embolism usually originates from a thrombus (blood clot) located in a deep vein in the leg. Before this thrombus becomes completely detached and causes an acutely life-threatening pulmonary embolism, smaller blood clots are usually torn away from the thrombus. They cause tiny embolisms in the lungs, which are therefore very rarely detected.

Symptoms such as reduced exercise tolerance, shortness of breath, coughing and dizziness can already occur with the small embolisms and should therefore be taken seriously. If the thrombus detaches completely, it usually closes a large pulmonary vessel. This leads to sudden chest pain and shortness of breath.

In addition, the affected person may suffer a shock, which is expressed by a greatly increased pulse rate. In this case immediate medical help is necessary. Even under a quickly initiated therapy it is possible that the pulmonary embolism also damages the heart.

Due to the blockage of the pulmonary vessels, the heart has to pump against an extremely high pressure. Due to the frequent lack of oxygen, however, it is not able to do this and can decompensate (it cannot perform the necessary additional work). This decompensation, which usually takes place in the right half of the heart, can cause permanent cardiac insufficiency (cardiac insufficiency), which is associated with a greatly increased mortality rate.