A pulmonary embolism (PE) occurs when a blood clot, often originating in the legs, travels to the lungs and blocks an artery. This blockage can disrupt blood flow and oxygen exchange, causing symptoms and complications. PE severity varies from minor to life-threatening. Understanding its classifications helps guide medical assessment and treatment.
Defining Submassive Pulmonary Embolism
Doctors categorize pulmonary embolisms into three main types: low-risk, submassive, and massive. A submassive pulmonary embolism is characterized by the patient maintaining stable blood pressure, meaning they are hemodynamically stable. The clot is significant enough to cause strain on the right side of the heart (right ventricle).
Right ventricular (RV) strain indicates that the heart’s right pumping chamber is working harder than it should to push blood past the obstruction in the pulmonary arteries. This increased workload can lead to the muscle stretching or not contracting efficiently. The presence of this RV strain, despite stable blood pressure, distinguishes a submassive PE from a low-risk PE, where such strain is absent. In contrast, a massive PE involves a patient experiencing dangerously low blood pressure or shock due to the clot’s extensive blockage.
Signs and Diagnostic Indicators
People with a submassive pulmonary embolism report symptoms like sudden shortness of breath, which may worsen with physical activity. A sharp chest pain, often described as pleuritic, may also be present, intensifying with deep breaths or coughing. A cough, sometimes with blood, or a rapid heart rate may also occur.
Specific diagnostic tests identify a submassive PE. A CT pulmonary angiogram (CTPA) is the primary imaging technique to visualize blood clots in the lung arteries. An echocardiogram (ultrasound of the heart) directly assesses the right ventricle for strain. Blood tests, including biomarkers like troponin and B-type natriuretic peptide (BNP), are also used. Elevated levels indicate heart muscle stress or injury.
Treatment Approaches
Managing a submassive pulmonary embolism involves strategies tailored to the individual patient. Anticoagulation (blood thinners) is the standard initial treatment for most PE cases, unless there are strong contraindications. These medications (e.g., heparin, warfarin, or direct oral anticoagulants) do not dissolve existing clots but prevent them from growing larger and stop new clots from forming, allowing the body’s natural processes to break down the existing clot.
For some patients with higher-risk submassive PE, advanced therapies, including thrombolysis, may be considered. These “clot-busting” drugs dissolve the blood clot, potentially leading to faster resolution of symptoms and heart strain. Systemic thrombolysis (given intravenously) carries a higher risk of bleeding complications, requiring careful consideration of the patient’s specific profile.
Another advanced option is catheter-directed therapy, a less invasive approach. During this procedure, a catheter is guided through blood vessels directly to the clot in the lungs. Through the catheter, clot-dissolving medication can be delivered directly to the clot, or a device can mechanically remove it. This localized approach aims to reduce bleeding risk compared to systemic thrombolysis, offering an alternative when more aggressive clot removal is needed. The choice of treatment balances potential clinical deterioration against the patient’s risk of bleeding.
Recovery and Long-Term Management
Following the acute treatment phase for a submassive pulmonary embolism, patients typically begin a period of recovery and long-term management. Anticoagulation therapy usually continues for at least three to six months, though the duration can extend indefinitely depending on the underlying cause of the clot. This extended treatment helps prevent future clot formation.
Regular follow-up appointments with healthcare providers are important to monitor the patient’s recovery. These visits may involve repeat imaging, such as echocardiograms, to ensure that the strain on the right side of the heart has resolved. Addressing underlying risk factors, such as prolonged immobility, recent surgery, or inherited clotting disorders, is also part of long-term care to reduce the likelihood of another PE. While most patients recover well, a small number may develop chronic thromboembolic pulmonary hypertension (CTEPH), a condition where blockages in the lung arteries persist or recur, leading to high blood pressure in the lungs. Patients are advised to report any returning symptoms to their doctor promptly.