Venous Thromboembolism
Overview
Venous thromboembolism consists of both deep venous thrombosis (DVT) and pulmonary embolism (PE).
Patients develop thrombosis or clots in their leg veins, often starting in the calf veins. If left untreated, these clots can spread upwards. Once the clot reaches the knee (popliteal) vein or above, it can break off and travel up into the lung, which can be fatal.
Most people who die from PE are not diagnosed or even suspected to have this disease until after they've died.
Symptoms
This disease often presents no symptoms at all or symptoms that lead to misdiagnoses. A patient may have sudden-onset shortness of breath and be diagnosed with a heart attack, pneumonia or asthma when PE is the actual disease. For nearly a quarter of pulmonary embolism patients, the first sign of their condition is death.
Pain and swelling in one or both legs is a common symptom of DVT. However, DVT can occur without symptoms and lead to fatal PE without any symptoms or warning signs.
Once a clot has traveled to the lung, the patient will have shortness of breath. This shortness of breath often is sudden.
Other symptoms of PE include:
- Chest pain that mimics a heart attack
- Severe pain with deep breaths (pleuritic chest pain)
- Light-headedness, fainting or seizures because not enough oxygen-rich blood is getting to the brain and other organs
- Irregular heartbeats
- Bluish skin (cyanosis)
- Sudden death
Diagnosis
Cedars-Sinai was one of the first hospitals to create a pulmonary embolism response team (PERT) to address DVT and PE. This program brings together a team of experts from different fields including pulmonology, radiology, interventional radiology, cardiology, interventional cardiology, cardiothoracic, hematology, internal medicine and surgery.
Once diagnosed, the team will assign a level of risk for each patient (low, intermediate or high). Factors that determine this risk level include severity of symptoms, heart rate, blood pressure, oxygen requirements, biomarkers like BNP and troponin, the echocardiogram, clot burden on CT or VQ scan, risk of bleeding and risk of adverse effects from procedures.
The D-dimer test is often used if DVT or PE are suspected. It measures a substance released when a blood clot breaks down. If this test is normal, DVT and PE are unlikely. However, the doctor may order an imaging study like a CT scan or a VQ scan to determine with more certainty if clots are present.
Treatment
Doctors often have little time to diagnose and treat DVT and PE, a disease which can be fatal. People at risk for developing blood clots should take preventive measures including the following:
- Stay active and move around every few hours, especially when traveling by air.
- After certain surgical procedures, patients—especially older people—may require a blood thinner at preventive doses, compression elastic stockings or devices that provide a rhythmic pressure on the legs that can keep blood moving. Leg exercises and getting out of bed as soon as feasible is key.
Once a risk assessment has been completed, treatment for DVT or PE may include the following:
- Anticoagulants (blood thinners) are the first line of treatment for a patient with DVT. They are so effective that patients often begin blood thinners when suspicion is high, even before diagnosis is finalized. Blood thinners like these prevent clots from forming or getting larger. Drugs to prevent the blood from clotting may be given for three months up to indefinitely, depending on the person's health and risk factors for developing more DVT.
- Some patients may take a direct oral anticoagulant, or DOAC. These agents have greatly simplified care—no blood test monitoring is needed, and drug interactions are infrequent.
- Drugs used to break up and dissolve clots, such as tissue-type plasminogen activators, may be given. These drugs must be considered cautiously in certain settings, such as recent surgery or other scenarios where the risk of bleeding is high.
- In cases where anticoagulants cannot be used, the doctor may implant an inferior vena cava filter (IVC filter). An IVC filter is a small, cone-shaped device placed in the inferior vena cava just below the kidneys. This filter can capture emboli on the way to the heart and lungs, preventing PE.
- Surgery (surgical embolectomy) may be needed in severe cases where the embolism is life-threatening and thrombolysis cannot be administered.
- In cases where DVT has led to high-risk pulmonary embolism and the heart cannot generate adequate flow in the lungs leading to hypertension, treatment may include thrombolytic therapy administered via IV or by infusion through a catheter directly into the lung.
- In extreme cases, the extracorporeal membrane oxygenation (ECMO) team will hook up the patient to a venous arterial ECMO machine to support the circulation, allowing time for a clot extraction procedure or until enough time passes that it breaks up on its own.
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