A pulmonary embolism (PE) is a serious condition that occurs when a blood clot gets lodged in an artery in the lungs, blocking blood flow. These clots most often originate in the deep veins of the legs, a condition known as deep vein thrombosis (DVT), and then travel through the bloodstream. Understanding how these clots can travel to the heart and lungs is crucial for prevention and prompt treatment.
What is Pulmonary Embolism?
A pulmonary embolism is a blood clot that obstructs blood flow to an artery in the lung. In the majority of cases, the clot originates in a deep vein, typically in the leg, and journeys to the lung. In rarer instances, the clot may form in a vein in another area of the body. When a blood clot develops in one or more of the deep veins in the body, it is referred to as deep vein thrombosis (DVT). Because these clots hinder blood flow to the lungs, a pulmonary embolism can be life-threatening if not promptly addressed.
Symptoms of a Pulmonary Embolism
Pulmonary embolism symptoms can vary widely, depending on the extent of lung involvement, the size of the blood clots, and the presence of underlying heart or lung disease. Common symptoms include:
- Sudden Shortness of Breath: This is a hallmark symptom, often appearing abruptly and worsening with physical activity or even at rest.
- Chest Pain: Often described as sharp and similar to a heart attack, the pain intensifies with deep breaths, coughing, bending, or leaning.
- Fainting (Syncope): A sudden drop in heart rate or blood pressure can lead to fainting.
Other potential symptoms include:
- Coughing up blood or blood-streaked mucus
- Rapid or irregular heartbeat
- Lightheadedness or dizziness
- Excessive sweating
- Fever
- Leg pain, swelling, or both, particularly in the lower leg
- Clammy or discolored skin (cyanosis)
It’s vital to seek immediate medical attention if you experience any of these symptoms.
How Blood Clots Travel to the Heart and Lungs
The process of a blood clot traveling from the legs to the lungs involves several steps:
- Formation in Deep Veins: Clots often form in the deep veins of the legs due to factors like prolonged inactivity, injury, or underlying medical conditions.
- Travel to the Heart: The clot breaks free and travels through the veins, making its way to the right side of the heart.
- Entry into the Pulmonary Artery: From the right side of the heart, the clot is pumped into the pulmonary artery, which carries blood to the lungs.
- Lodging in the Lungs: The clot eventually becomes lodged in a smaller artery in the lungs, blocking blood flow.
Causes of Pulmonary Embolism
Pulmonary embolism occurs when a clump of material, usually a blood clot, blocks an artery in the lungs, hindering blood flow. These clots frequently originate in the deep veins of the legs, a condition known as deep vein thrombosis.
In many cases, multiple clots may be involved. The portions of the lung served by the blocked artery cannot receive blood and may undergo tissue death, known as pulmonary infarction. This makes it more difficult for the lungs to supply oxygen to the rest of the body.
Less commonly, blockages in the blood vessels can be caused by substances other than blood clots, such as:
- Fat from the interior of a fractured long bone
- Part of a tumor
- Air bubbles
Risk Factors for Blood Clots and Pulmonary Embolism
Several factors can increase the risk of developing blood clots that can lead to a pulmonary embolism.
Medical History
- Previous Blood Clots: A personal or family history of venous blood clots or pulmonary embolism elevates the risk.
- Heart Disease: Conditions affecting the heart and blood vessels, particularly heart failure, increase the likelihood of clot formation.
- Cancer: Certain cancers, like those of the brain, ovary, pancreas, colon, stomach, lung, and kidney, along with cancers that have spread, heighten the risk. Chemotherapy further increases this risk. A personal or family history of breast cancer, especially with tamoxifen or raloxifene use, also contributes.
- Surgery: Surgery is a major cause of problem blood clots. Preventative medicine is often administered before and after major surgeries like joint replacements.
- Clotting Disorders: Some inherited disorders and medical conditions, such as kidney disease, can affect blood clotting, making it more likely.
- COVID-19: Individuals with severe COVID-19 symptoms have an elevated risk of pulmonary embolism.
Lifestyle and Other Factors
- Prolonged Inactivity: Extended periods of inactivity, such as bed rest after surgery or illness, or long trips, increase the risk of blood clots due to slowed blood flow.
A blood clot in a leg vein may cause swelling, pain, warmth and tenderness in the affected area.
- Smoking: Tobacco use is linked to an increased risk of blood clots, particularly in individuals with other risk factors.
- Obesity: Excess weight increases the risk of blood clots, especially when combined with other risk factors.
- Estrogen Supplements: Estrogen in birth control pills and hormone replacement therapy can increase clotting factors, particularly in smokers or those who are overweight.
- Pregnancy: The pressure of the baby on pelvic veins can slow blood return from the legs, increasing the likelihood of clot formation.
Complications of Pulmonary Embolism
A pulmonary embolism can be life-threatening. About one-third of people with an undiagnosed and untreated pulmonary embolism do not survive. However, when the condition is diagnosed and treated promptly, that number drops dramatically.
Pulmonary embolisms can also lead to pulmonary hypertension, where blood pressure in the lungs and the right side of the heart is too high. Blockages in the pulmonary arteries force the heart to work harder, increasing blood pressure and weakening the heart.
In rare cases, small clots can remain in the lungs, leading to scarring in the pulmonary arteries over time. This restricts blood flow and results in chronic pulmonary hypertension.
Prevention Strategies
Preventing clots in the deep veins of the legs is crucial for preventing pulmonary embolisms. Most hospitals take aggressive measures to prevent blood clots, including:
- Anticoagulants (Blood Thinners): These medications are often prescribed to individuals at risk of clots before and after surgery, as well as to those admitted to the hospital with certain medical conditions.
- Compression Stockings: These stockings steadily squeeze the legs, helping veins and leg muscles move blood more efficiently, preventing blood from pooling in the legs.
- Leg Elevation: Elevating the legs, especially during the night, can be very effective. Raise the bottom of the bed 4 to 6 inches (10 to 15 cm) with blocks or books.
- Physical Activity: Moving as soon as possible after surgery can help prevent pulmonary embolism and hasten overall recovery.
- Pneumatic Compression: This treatment involves thigh-high or calf-high cuffs that automatically inflate and deflate, massaging and squeezing the veins in the legs to improve blood flow.
Prevention During Travel
The risk of blood clots developing during travel is low but increases with long-haul travel. If you have risk factors for blood clots and are concerned about travel, consult your healthcare provider.
Your provider might suggest the following to help prevent blood clots during travel:
- Drink Plenty of Fluids: Water is the best liquid for preventing dehydration, which can contribute to the development of blood clots. Avoid alcohol, which contributes to fluid loss.
- Take a Break from Sitting: Move around the airplane cabin once an hour or so. If you’re driving, stop every so often and walk around the car a couple of times. Do a few deep knee bends.
- Move in Your Seat: Bend and make circle movements with your ankles and raise your toes up and down every 15 to 30 minutes.
- Wear Support Stockings: Your provider may recommend these to help promote circulation and fluid movement in your legs.
Conclusion
Understanding how blood clots can travel to the heart and lungs is essential for recognizing the signs and symptoms of a pulmonary embolism and taking preventative measures. Prompt diagnosis and treatment are crucial for improving outcomes and reducing the risk of life-threatening complications. If you suspect you may be at risk or are experiencing symptoms, seek immediate medical attention.
