Saddle pulmonary embolism describes a large blood clot that sits atop or “saddles” the main pulmonary artery where it divides and branches into the left and right lungs. It can cause breathing problems.

Saddle PE is a severe and life threatening condition that requires immediate medical attention. Without treatment, the condition can result in sudden death.

This article describes what saddle PE is, including its causes, risk factors, and possible signs and symptoms. We also discuss how to treat and prevent saddle PE and offer advice on seeking help.

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Saddle pulmonary PE is a type of sudden or acute PE. It is a rare occurrence, accounting for 2.6–5.4% of all acute PE cases.

The condition occurs when a large blood clot becomes lodged at the intersection where the main pulmonary artery divides and branches off into the left and right lungs.

The main pulmonary artery carries deoxygenated blood from the heart to the lungs, where it becomes reoxygenated.

A blockage at the intersection where the main pulmonary artery divides prevents blood flow to both lungs. This causes blood pressure to drop or become unstable, resulting in inadequate blood supply to the entire body. Insufficient blood flow causes damage to the organs, including the brain, heart, and kidneys.

Saddle PE can cause heart failure and sudden death without urgent medical treatment.

According to the American Society of Hematology, blood clotting is a typical bodily process that helps seal wounds and prevent bleeding. Over time, the body naturally breaks down the blood clot and absorbs it back into the bloodstream.

However, blood clots can cause issues if they form without injury or fail to dissolve back into the bloodstream.

The most common cause of PE is a blood clot that forms within the deep veins of the arms, legs, or pelvis. Doctors refer to this as deep vein thrombosis (DVT).

Anybody can develop blood clots. However, men have a higher overall risk compared to women. Some factors that can increase a person’s risk of developing blood clots are below.

Increased estrogen

Increased levels of the hormone estrogen can increase the risk of blood clots. Some factors that may cause a rise in estrogen levels include:

Learn more about pulmonary embolism and blood clots during pregnancy.

Reduced or impaired blood flow

Reduced or impaired blood flow can causeblood to pool in the vessels, increasing the risk of blood clots. Some factors that can affect blood flow include:

  • not moving for long periods due to bed rest, trauma, or injury
  • sitting for more than 4–6 hours at a time, such as in a car or airplane
  • wearing a cast
  • paralysis

Injuries to a vein

Injury to a vein causes blood to clot within the vein. If the body does not break down and reabsorb the blood clot, it may impair blood flow or travel to other parts of the body. Some factors that could cause injury to a vein include:

Chronic medical conditions

Some chronic medical conditions can increase a person’s risk of developing blood clots. Examples include:

Other factors

Some other factors that increase a person’s risk of developing blood clots and associated DVTs and PEs include:

Signs and symptoms of saddle PE include:

It is important to note that the symptoms of a pulmonary embolism are very similar to those of a heart attack.

A person with saddle PE requires immediate medical attention and may require admission to an intensive care unit at the hospital.

The aim of treatment is to break up the blood clot to restore blood flow to the lungs while also preventing new clots from forming. Below are the main treatment options.


Doctors may provide the following medications for PE:

  • Anticoagulants, such as heparin and warfarin: These medications prevent existing clots from growing larger and prevent new clots from forming. Doctors may give the medication in the form of a pill or intravenous injection.
  • Thrombolytics: These medications dissolve blood clots. However, a possible side effect is sudden bleeding. As such, doctors typically reserve thrombolytics for severe and life threatening PEs such as saddle PEs.


  • Vena cava filter: This procedure involves placing a small metal filter inside a large vein called the “vena cava” to prevent blood clots from reaching the lungs. The procedure may be helpful for people who cannot take blood thinners.
  • Percutaneous thrombectomy: Doctors insert a flexible, hollow tube called a catheter to help remove or break up the blood clot. One method involves suctioning the blood clot through the catheter. Another approach involves inserting tiny instruments into the catheter to manually help break up the blood clot. A person will be under general anesthesia for this procedure.

According to the Centers for Disease Control and Prevention (CDC), people at risk of developing blood clots can take the following precautions to help reduce their risk:

  • being physically active
  • maintaining a moderate weight
  • wearing comfortable, loose-fitting clothing
  • moving around as soon as medically appropriate following an injury or surgery
  • wearing compression stockings
  • taking aspirin

People who need to sit for more than 4 hours at a time can do the following exercises to help maintain circulation in the legs:

  • standing and walking around every 1 to 2 hours
  • tightening and releasing the leg muscles
  • raising and lowering the toes while keeping the heels on the floor
  • raising and lowering the heels while keeping the toes on the floor

Saddle PE can cause life threatening complications.

Around 1 in 4 people who develop any form of pulmonary embolism die instantly. Another 10-30% die within a month of diagnosis.

A 2021 study assessed the outcomes of 120 patients with saddle PE at one hospital between 2012 and 2018. Of these patients, the researchers found that 9.2% died at the hospital, with a further 8.6% dying within 6 months of discharge.

The most crucial factor determining a person’s outlook is whether they receive treatment within the first few hours of the blockage. Early detection and urgent medical care reduce fatality and increase the likelihood of a full recovery.

A person with a diagnosis of saddle PE needs to take anticoagulant injections for at least 5 days and then anticoagulant tablets for at least 3 months.

A person should seek urgent medical attention if they experience any of the following symptoms:

  • sudden and severe breathing difficulties
  • very fast or irregular heartbeat
  • fainting or feeling faint

Anyone at risk of developing blood clots should ask their doctor for tips on blood clot prevention and management.

Some people may need to take medications to prevent or manage blood clots. Some questions to ask a doctor include:

  • What do the medications do?
  • What dosage should I take and when?
  • How long do I need to take the medication?
  • Do I need to attend regular check-ups or screenings while taking the medication?
  • What are the side effects of the medication, and what do I do if I experience side effects?
  • What are the potential benefits and risks of taking the medication?

Saddle pulmonary embolism (PE) is an uncommon yet life threatening type of PE.

In saddle PE, a blood clot becomes lodged at the intersection where the main pulmonary artery divides and branches into the left and right lungs. Immediate treatment is necessary to restore blood flow to the lungs and prevent complications, including death.

Anyone can develop blood clots. Factors that can increase the risk include increased estrogen levels, injury to a vein, and reduced or impaired blood flow. People at increased risk of developing blood clots can consult their doctor for advice on blood clot prevention or management.

Individuals who receive a diagnosis of saddle PE require constant monitoring and continuous medications to prevent the condition from recurring.