A pulmonary embolism (PE) is a blood clot that travels to the lungs, most often from a leg vein — a potentially life-threatening emergency that needs immediate treatment. In a small number of people, clots don't fully resolve and instead cause a chronic condition called CTEPH, a distinct long-term form of pulmonary hypertension.
What Is a Pulmonary Embolism?
A blockage in one of the arteries carrying blood from the heart to the lungs, almost always caused by a blood clot that has traveled from elsewhere in the body — most commonly a deep vein in the leg (see Deep Vein Thrombosis). The blockage strains the heart's right side and reduces oxygen delivery, with severity ranging from small and manageable to immediately life-threatening.
What's Happening in Your Body
When a clot lodges in a lung artery, blood flow to part of the lung is reduced or blocked entirely, which both impairs oxygen exchange and forces the heart's right side to work harder against the sudden blockage. A large PE can overwhelm the right heart's ability to compensate, causing a sudden, dangerous drop in blood pressure — this is what makes a large PE a genuine emergency.
Acute Pulmonary Embolism
This is the sudden event most people mean by "PE" — a clot arrives in the lung circulation, typically within hours to days of forming (often from a DVT), causing sudden shortness of breath, chest pain, and sometimes a fast heart rate or fainting. Severity is classified from low-risk (small clot, stable vital signs) to massive (causing severe strain on the heart and low blood pressure) — this classification directly determines how urgently and aggressively it's treated, and is typically assessed using a combination of vital signs, imaging findings, and blood markers of heart strain.
Chronic Thromboembolic Pulmonary Hypertension (CTEPH)
In a small percentage of people who have had a pulmonary embolism, clot material doesn't fully dissolve and instead becomes chronic, scarred tissue that permanently narrows the lung arteries — over months to years, this raises pressure in the lung circulation and strains the right heart, a specific and distinct form of pulmonary hypertension (this is "Group 4" in the broader pulmonary hypertension classification — see Pulmonary Hypertension). CTEPH is under-recognized because its main symptom, gradual shortness of breath, can be mistaken for simply not having fully recovered from the original PE, or for deconditioning — which is exactly why anyone with lingering breathlessness months after a PE deserves a specific evaluation for it.
Common Symptoms
Acute PE — sudden shortness of breath, chest pain (often worse with breathing), a fast heart rate, coughing (sometimes with blood), lightheadedness, or fainting in more severe cases.
CTEPH — gradually worsening shortness of breath with exertion over months, often the main or only symptom, sometimes with fatigue or swelling as it progresses — the gradual pace is exactly what makes it easy to overlook.
How It's Diagnosed
Acute PE is typically diagnosed with a CT pulmonary angiogram, sometimes alongside a D-dimer blood test and an assessment of right heart strain (echocardiogram, blood tests like troponin/BNP). CTEPH is diagnosed with a ventilation-perfusion (V/Q) scan (more sensitive than CT for this specific chronic pattern), confirmed with right heart catheterization and specialized imaging of the pulmonary arteries. (See Cardiac Testing & Imaging and Pulmonary Hypertension.)
Main Treatment Options
Acute PE is treated with anticoagulation in most cases (see Anticoagulants); larger or more dangerous PEs may require clot-dissolving medication (thrombolysis) or catheter-based clot removal, and the most severe cases sometimes need temporary mechanical circulatory support. CTEPH has its own specific treatments beyond standard anticoagulation: pulmonary thromboendarterectomy (a specialized surgery to remove the chronic scarred clot material, potentially curative in appropriate candidates, performed at specialized centers with significant experience in this specific operation), balloon pulmonary angioplasty (a catheter-based option for patients who aren't surgical candidates or have residual disease after surgery), and specific pulmonary-hypertension-pathway medications for patients with residual disease (see Group 1 Pulmonary Hypertension Medications for how this medication category generally works, adapted under specialist guidance for CTEPH).
Lifestyle Changes That Help
- Completing your full prescribed course of anticoagulation, exactly as directed
- Following up on any lingering shortness of breath after a PE rather than assuming it's just prolonged recovery — this is precisely how CTEPH gets caught earlier
- The same DVT-prevention habits that reduce future clot risk (see Deep Vein Thrombosis)
- Coordinated care between your pulmonologist, cardiologist, and, for CTEPH, a specialized PH/CTEPH program
Living With It
Most people recover well from an acute PE with appropriate anticoagulation, returning to normal activity over weeks to months. CTEPH is a more complex, chronic condition, but it's one of the few forms of pulmonary hypertension that can potentially be cured with surgery in the right candidate — which is exactly why accurate diagnosis and referral to an experienced CTEPH program matters so much.
When to Call Your Doctor vs. Go to the ER
- Gradually worsening shortness of breath in the months after a treated PE
- Sudden shortness of breath, chest pain, a racing heart, coughing up blood, or fainting — always treat suspected PE as an emergency
Common Questions
How long will I need blood thinners after a PE?
Similar to DVT, commonly at least three months, sometimes longer or indefinitely depending on your specific cause and ongoing risk factors — your care team individualizes this.
I had a PE months ago and I'm still short of breath — is that normal?
It can take time to fully recover, but persistent or worsening breathlessness deserves a specific evaluation for CTEPH rather than being assumed to be normal prolonged recovery.
Can CTEPH actually be cured?
For appropriate surgical candidates, pulmonary thromboendarterectomy can be potentially curative — a genuinely different situation from most other forms of pulmonary hypertension, which is why getting evaluated at an experienced center matters.
How common is CTEPH after a PE?
It develops in a small minority of PE patients, but exact estimates vary across studies — the key practical point is that it's uncommon enough to not expect, but common enough that persistent breathlessness after a PE deserves a specific look rather than automatic reassurance.
How is a PE actually diagnosed?
Most commonly with a CT pulmonary angiogram (a CT scan with contrast dye specifically timed to show the lung arteries), sometimes alongside a blood test called D-dimer that helps determine how likely a clot is before deciding whether imaging is needed. (See Cardiac Testing & Imaging.)