Types of pulmonary embolism

Acute massive pulmonary embolism is a leading cause of death in patients admitted to the hospital

Pulmonary embolism (PE) is a condition where blood clots that originate elsewhere in the body break off and travel to the vasculature of the lungs to block the blood flow from the right side of the heart to the left side.

Pulmonary embolism can be minor when a small portion of the lung vasculature is involved, or it may be massive if the majority of the vasculature is involved and circulation is compromised by this dangerous blood clot.

Pulmonary embolism symptoms

Patients with pulmonary embolism often have a variety of symptoms, including chest pain and shortness of breath. However, these symptoms are not specific for pulmonary embolism, and the diagnosis depends on the clinician having a high index of suspicion.

  • Patients with PE who have reduced blood pressure are referred to as having a massive pulmonary embolism
  • Patients who have normal blood pressure, but whose right heart is under strain, are said to have sub-massive pulmonary embolism
  • Patients with neither have stable pulmonary embolism

Testing for pulmonary embolism

The most common pulmonary embolism test is a venous phase CT angiogram. This quick and accurate blood clot test provides all the information needed for initial pulmonary embolism treatment. Unfortunately, the need for contrast dye makes the test risky in patients with renal dysfunction (kidney dysfunction).

A VQ scan is an alternative test, but it does not distinguish between acute and chronic pulmonary embolism. An echocardiogram is important to look at the function of the right heart to see if any thrombus (blood clot) is present in the heart that could cause additional compromise to the lung circulation and may constitute an indication for emergency heart surgery.

Pulmonary embolism response team (PERT)

Time is of the essence with acute massive pulmonary embolism treatment. The management of pulmonary embolism involves multiple specialists with a wide range of expertise. The PERT is organized to simultaneously communicate to all the specialists and promptly activate the required resources to manage acutely ill heart patients.

Options include blood thinners (anticoagulation and fibrinolysis), catheter-based therapies and emergent heart surgery. We are happy to transfer patients from other institutions for these advanced therapies to treat pulmonary embolism.



Many patients with chronic thromboembolic pulmonary hypertension (CTEPH) are unaware they had an acute pulmonary embolism.

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About 2-4% of all patients with pulmonary embolism do not resolve their acute thrombus (blood clot). They then enter a chronic phase where the vascular pressures in the lung elevates, putting a strain on the right ventricle and eventually causing it to fail. Many patients with chronic thromboembolic pulmonary hypertension (CTEPH) are unaware they had an acute pulmonary embolism. CTEPH is a common cause of unexplained pulmonary hypertension (elevated vascular pressure in the lungs). 


Common CTEPH symptoms include chest pain, palpitations, syncope and shortness of breath. Patients often have signs of right heart failure, including leg swelling. Any patient whose symptoms do not resolve within three months of an acute pulmonary embolism needs to be checked for CTEPH by a heart doctor.


The initial screening test to diagnose chronic thromboembolic pulmonary hypertension is an echocardiogram to look for evidence of elevated lung pressures and right heart failure. Any patient with unexplained pulmonary hypertension should undergo a VQ scan. If the scan shows normal perfusion, CTEPH is ruled out. If the VQ scan is positive, patients should receive a CT angiogram and a right heart catheterization.


Chronic thromboembolic pulmonary hypertension treatment requires care from a multidisciplinary team. The entire team reviews each patient to attain consensus before management. CTEPH is surgically curable. In patients who have favorable anatomy, a procedure called pulmonary thromboendarterectomy (PTE) can reduce pressures and reverse the patient’s hypertension symptoms. Patients who have residual hypertension after surgery, and those who are not candidates for surgery, are managed by pulmonary hypertension specialists. There are now medications designed specifically to treat patients with chronic thromboembolic pulmonary hypertension.