Thromboangiitis obliterans

Pulmonary thromboembolism (Pulmonary thromboembolism)

1) Description of the disease (causes and symptoms)

• Causes and pathophysiology
  • A blood clot formed in the legs (mainly in the deep veins) travels through the bloodstream and blocks the pulmonary artery or one of its branches. When the pulmonary vessels are obstructed, ventilation-perfusion mismatch and hypoxia occur, and increased pulmonary vascular resistance may place a strain on the right ventricle and cause right heart failure.
  • Major risk factors: recent surgery/trauma, prolonged inactivity (long-term hospitalization, flights), cancer and anticancer treatment, pregnancy·the postpartum period, oral contraceptives·hormone therapy, a personal or family history of thrombosis, obesity, smoking, central venous catheterization, older age, heart failure·kidney failure, etc.
• Main symptoms
  • Acute shortness of breath, chest pain (pleuritic pain), tachycardia, fainting/dizziness, anxiety·sweating, hemoptysis, and cough.
  • Signs of severe disease: hypotension (systolic blood pressure < 90–100 mmHg), shock index (pulse/systolic blood pressure) > 1, and a high risk of death in cases of acute cardiac arrest or right ventricular failure.

2) Treatment methods and precautions

• Acute-phase treatment (goals: prevent death, suppress recurrence, and prevent long-term complications)
  • Anticoagulant therapy (the initial treatment for most patients)
    • Low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH): used for emergency and early inpatient treatment.
    • Oral anticoagulants: DOACs (rivaroxaban, apixaban, edoxaban, etc.) — recommended as first-line options for patients without cancer. Warfarin (target anticoagulation INR 2.0–3.0) is used when DOACs cannot be used.
    • Treatment duration: generally 3 months for provoked cases (surgery·trauma, etc.). If there is no provoking cause or the risk of recurrent thrombosis is high, extended treatment (6 months or longer, and in some cases lifelong) may be considered.
  • Thrombolysis
    • Indicated in cases of massive pulmonary embolism with hypotension·signs of severe right heart failure (life-threatening).
    • Medical thrombolytic therapy (e.g., tPA) or catheter-based thrombolysis.
  • Mechanical removal and surgery
    • Catheter embolectomy or surgical pulmonary embolectomy (considered in emergencies).
  • Inferior vena cava (IVC) filter
    • Temporary or permanent filter placement may be considered to prevent a blood clot from traveling to the heart when anticoagulant treatment is contraindicated or recurrence occurs during anticoagulant treatment.
• Supportive care
  • Oxygen therapy, hemodynamic support (fluids·vasoconstrictors), and, if necessary, intensive care·extracorporeal membrane oxygenation (ECMO) may be considered.
• Precautions and monitoring
  • Assess bleeding risk (when using anticoagulants) and perform regular monitoring (INR in the case of warfarin).
  • Monitor for thrombocytopenia (HIT) when using heparin.
  • D-dimer has high sensitivity but low specificity (useful for exclusion when negative if clinical suspicion is low).
  • A plan for interruption and resumption is needed before surgical procedures·dental treatment during anticoagulant therapy.
  • Consider discontinuing hormonal medications (oral contraceptives·hormone replacement therapy).
• Complications
  • Pulmonary infarction·cor pulmonale (chronic thromboembolic pulmonary hypertension), right heart failure, recurrent embolism, bleeding (related to anticoagulants), and death.

3) Checklist before an outpatient visit (recommended items and example questions)

• Items to bring (recommended)
  • List of current medications (including anticoagulants·antiplatelet agents·hormonal medications), recent test results (recent INR, kidney function·liver function tests), previous electrocardiograms·chest imaging (CT, V/Q scan, etc.) and surgical·clinical records, and allergy history.
  • Symptom diary: time symptoms began, severity of shortness of breath (during activity vs. at rest), presence of chest pain·hemoptysis·fainting, and factors that worsen symptoms.
• Information to ask about during the outpatient visit (items to tell the doctor)
  • Recent surgery·history of bleeding, whether you are pregnant or breastfeeding, a diagnosis of cancer·history of anticancer treatment, and recent long-distance travel·prolonged bed rest.

4) Examples of general questions to ask the doctor

• What are the main side effects of this anticoagulant (or thrombolytic), and what should I do if bleeding occurs?
• How long do I need to continue anticoagulation in my case? What are the criteria for extended treatment?
• What precautions should I take regarding daily activities·exercise·antibiotics·travel·dental treatment during anticoagulant therapy?
• How should anticoagulant therapy be adjusted if I am planning a pregnancy (or am currently pregnant)?
• Do I need additional tests to lower the risk of recurrence (thrombophilia testing·cancer screening, etc.)?

5) Examples of disease-specific questions

• How high-risk is my pulmonary embolism: ‘massive,’ ‘submassive,’ or ‘small’? (Right ventricular dysfunction and hemodynamic stability need to be monitored.)
• Considering my current kidney function·liver function·concomitant medications, can I use a DOAC? Which DOAC would be appropriate?
• If I need to stop anticoagulant therapy or undergo surgery, when and how should I resume it?

Emergency signs: If sudden severe shortness of breath, fainting·loss of consciousness, persistent·large-volume hemoptysis, or symptoms of hypotension (dizziness·blurred vision, etc.) occur, visit the emergency room immediately.