Pulmonary thromboembolism and infarct Flashcards
What is the commonest cause of pulmonary embolism?
Venous thrombosis forms in the leg or pelvis (iliofemoral vein). Clots break off and pass through veins and right side of the heart before lodging into pulmonary circulation
Rare causes
RV thrombosis Septic emboli (right sided endocarditis) Fat Air Amniotic fluid Neoplastic cells Parasites
Risk factors for PE?
Prolonged immobility Recent surgery Thrombophilia (e.g. antiphospholipid syndrome) Leg fracture Malignancy Pregnancy/ postpartum/ pill/ HRT
Size of embolus determines severity. What occurs in a massive embolus?
A massive embolism will fully occlude right ventricular outflow
Increase in pulmonary vascular resistance will cause right heart failure
What occurs in a small embolus?
Small embolus will impact in a terminal, peripheral pulmonary vessel – may be clinically silent unless it causes pulmonary infarction
Lung tissue is ventilated but not perfused – impaired gas exchange
What prevention is undertaken to prevent PE?
Give heparin to all immobile patients
Prescribe compression stockings
Early mobilisation
Stop hormone replacement therapy and the pill pre-op
How does heparin (and fondaparinux) act?
inhibit formation of factor 10a, so prothrombin is not converted to thrombin and subsequently fibrinogen is not converted to fibrin. Prevents thrombus formation
Clinical symptoms?
Pleuritic chest pain
Acute breathlessness
Dizziness and syncope
Haemoptysis
Clinical signs?
Pyrexia Cyanosis Tachypnoea and tachycardia Hypotension Raised JVP Pleural rub Pleural effusion
Blood tests and results for PE?
FBC and U&E to determine baseline clotting
D dimer test- negative d dimer test will exclude PE (positive doesn’t confirm)
ABG may show low PaO2 and low PaCO2
What imaging tests are done for PE?
CXR- show oligaemia (low blood flow) of the effected segment: dilated pulmonary artery, linear collapse, small pleural effusion, wedge-shaped opacities
CT pulmonary angiography- will show clots down to 5th order pulmonary arteries
An ECG may reveal the cause of a pulmonary embolism? What may it show?
Normal OR:
Tachycardia
RBBB
Right ventricular strain (inverted T in V1 to V4)
What are causes of RBBB?
RB hypertrophy
Pulmonary embolism
Ischaemic heart disease
Treatment for PE?
Anti-coagulate with LMW heparin (faster acting)
Start warfarin
Stop heparin when INR > 2 and continue warfarin
Thrombolysis for massive PE
If thromboemboli continue to develop despite adequate anti-coagulation add a veno-caval filter.
