Causes of PE

Most blood clots (embolisms) that travel to the lungs are believed to come from deep veins of the lower body. The risk of developing serious complications and death depends mostly on the size of the blood clot that has traveled to the lungs. It also depends on the health of the patient’s veins. If a very large clot lodges inside the arteries near the lungs, blood cannot be pumped properly from the heart. This leads to death of healthy cells.

The PE patient’s health and age affects the seriousness of the problem. According to the Center for Disease Control & Prevention, people who are at the highest risk for death due to PE are those who already have partial blockages in their arteries, have experienced a recent vein injury, or who a history of heart disease. (5) People who are older and have many risk factors for pulmonary embolism, such as high levels of inflammation and arterial damage due to an unhealthy lifestyle, are much more likely to die from PE than younger, healthier people.

Risk factors for pulmonary embolism (which are similar to risk factors for deep vein thrombosis) include:

• Older age (especially between 60-75): The risk for blood clots increases with older age. Older adults are more likely to have arterial damage and risk factors for PE such as deep vein thrombosis compared to younger adults. This is especially true if they’re already suffering from another chronic illness, obese or overweight. The risk for PE in children is believed to be as low as 1 in 1 million. However, the risk doubles with each decade of life after the age of 40.

• Being overweight: Being very overweight or obese is linked to a higher risk for blood clots, due to changes in inflammation, blood pressure and possibly because of how excess fat tissue increases estrogen levels.

• Too little exercise (a sedentary lifestyle): An inactive lifestyle increases risk for poor blood flow and clot development. The highest risk is seen in those who have been very inactive due to factors like pregnancy, obesity, bed rest or surgery. These can all contribute to blood pooling. Although less of a risk, circumstances like taking long plane or car rides, sitting at a desk all day, watching TV for many hours and immobilization after surgery may lead to development of a clot that can start the process of DVT.

• A history of previous blood clots, heart attack or stroke: People who have a history of arterial damage, unhealthy blood pressure, a heart attack, stroke or heart disease are more likely to have clots than those without any history of cardiovascular problems. Those who have had injuries to veins, such from some surgical procedures or even traumatic impacts, can also develop an embolism or DVT more easily.

• Hospitalization: Around 20 percent of all cases of PE happen in the hospital. This is usually due to triggers like immobilization, healing from surgery, recovering from another illness, dealing with trauma or stress, blood pressure changes, being treated with an intravenous catheter (these increase risk for clotting) or infections.

• High amounts of stress or trauma: Experiencing a traumatic event (physical or even mental) may increase risk for DVT or PE tenfold! (06) Trauma and stress increase the level of clotting factors in the blood. They can also increase inflammation, change hormones and alter blood pressure levels.

• Recent infections: A recent serious infection increases risk for embolisms and DVT due to an effect on inflammatory processes, clotting and blood pressure.

• Chronic diseases (such as history of cancer, autoimmune disease or arthritis). Studies have found that a history of certain types of conditions including cancer, lupus, arthritis, diabetes, kidney disease and inflammatory bowel disease may all contribute to clots. Any condition that causes damage to blood vessels and cells in the lung may increase clotting.

• Smoking and drug use: All of the risk factors described above are worse when you smoke cigarettes, use other tobacco products, drink too much alcohol or use recreational drugs.

• Menopause and hormonal changes: Some research shows that changes in estrogen, including increased estrogen due to taking birth control pills or hormone replacement therapy drugs, can increase blood clotting and cause various heart complications. Menopausal women taking drugs to replace estrogen are also at a higher risk if they smoke, are overweight and don’t exercise.

• Pregnancy: Women seem to have a higher risk for developing clots during pregnancy and right after giving birth. Reasons for this include producing extra blood to support the fetus, more pressure being applied to veins, changes in blood pressure and obesity/weight gain. A scary finding is that pulmonary embolism is one of the leading causes of maternal death during birth.

• Genetic factors: Certain inherited traits can lead to genetic blood-clotting disorders, or the production of too many platelets. This causes blood to clot too easily and makes clot formation more likely. However, usually other risk factors are involved for a clot to form.