thrombotic disoders Flashcards

1
Q

What is venous thromboembolism (VTE)?

A

Venous thromboembolism (VTE) is the process of blood clot formation in the veins. It includes deep vein thrombosis (DVT) and pulmonary embolism (PE).

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2
Q

What is provoked VTE?

A

Provoked VTE refers to a VTE event that has a clear precipitating cause identified from the patient’s history or diagnostic tests

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3
Q

What is unprovoked VTE?

A

Unprovoked VTE refers to a VTE event that does not have a clear cause identified from the patient’s history or diagnostic tests.

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4
Q

What is thrombophilia?

A

Thrombophilia is a condition in which the blood in the body clots more easily than normal. This can increase the risk of developing blood clots, including VTE.

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5
Q

What are the three components of Virchow’s triad?

A

The three components of Virchow’s triad are circulatory stasis, hypercoagulable state, and vascular injury.

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6
Q

What are some causes of circulatory stasis?

A

Causes of circulatory stasis include bed rest, lower limb orthopaedic surgery, major abdominal surgery, pregnancy, and long haul flights or long car journeys.

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7
Q

What are some causes of hypercoagulable states?

A

Causes of hypercoagulable states include smoking, oestrogens (oral contraceptives, HRT), active cancer, and inherited and acquired thrombophilias.

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8
Q

What are some causes of vascular injury?

A

Causes of vascular injury include limb trauma including surgery, foreign bodies such as IV cannulae and pacemaker wires, sepsis, bacteria and toxins, previous DVT, and May Thurner Syndrome.

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9
Q

What is venous thromboembolism (VTE)?

A

Venous thromboembolism (VTE) is the process of blood clot formation in the veins. It includes deep vein thrombosis (DVT) and pulmonary embolism (PE).

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10
Q

What are the common clinical presentations of DVT?

A

Unilateral calf swelling, heat, pain, redness, and hardness. However, DVT can be asymptomatic or without any signs.

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11
Q

What is the commonest site of DVT?

A

The leg, particularly the calf (popliteal and tibial veins) and the thigh (femoral and iliac veins).

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12
Q

What are the differential diagnoses of DVT?

A

Baker’s cyst, cellulitis, muscular pain. A detailed history to determine any risk factors is key to differentiating DVT from other conditions.

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13
Q

What is the investigation of choice for DVT?

A

Doppler ultrasound, which is quick, safe, and provides real-time 2D images. Colour Doppler (Duplex) can show the direction and velocity of blood flow, and thrombosed veins are non-compressible. A D-dimer test can be useful to rule out DVT if the probability is low. Contrast venography is rarely required, but can be useful in extensive disease or to look for anatomical malformations.

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14
Q

How is DVT managed?

A

Treatment usually involves anticoagulation with heparin or low-molecular-weight heparin (LMWH), followed by warfarin or direct oral anticoagulants (DOACs). Compression stockings can be used to reduce swelling and prevent post-thrombotic syndrome. In severe cases or if anticoagulation is contraindicated, a filter can be inserted into the inferior vena cava to prevent pulmonary embolism.

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15
Q

What is D-dimer and how is it used in the diagnosis of DVT/PE?

A

D-dimer is a breakdown product from fibrin, the fibrous mesh component of blood clots. It is only present when the coagulation system has been activated and is elevated in venous thromboembolism. A D-dimer test is very sensitive and can be used to rule out DVT/PE if low probability. However, it is not very specific, and a positive test is not diagnostic. In cases of high clinical probability, a D-dimer test should not be used.

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16
Q

How is DVT treated?

A

The treatment of DVT depends on the location and extent of the clot. Symptomatic treatment is recommended for calf-only DVT, while ilio-femoral DVT requires anticoagulation with Direct Oral Anticoagulant (DOAC) such as Rivaroxaban or Dabigatran. The duration of treatment is usually 3-6 months for the first event and lifelong for the second event. In case of renal dysfunction, Warfarin may be used. Thrombophilia testing should be considered in individuals with a first-degree relative with VTE.

17
Q

What is CTPA and when is it used in the investigation of pulmonary embolism (PE)?

A

CTPA stands for CT pulmonary angiogram, which is a diagnostic imaging test that uses X-rays and contrast dye to create detailed images of the pulmonary arteries to detect any blockages or blood clots that could indicate a pulmonary embolism (PE). CTPA is only used if there is a reasonable likelihood of PE, and its use is guided by the Wells score, which takes into account various clinical features and risk factors for PE. In patients with a low probability of PE, a D-dimer test is usually done first, and CTPA is only done if the D-dimer test is positive.

18
Q

What is a ventilation-perfusion lung scan?

A

A ventilation-perfusion lung scan is a nuclear medicine test that uses inhaled and injected radioisotopes to identify a mismatch between lung ventilation and perfusion.

19
Q

What is the limitation of a ventilation-perfusion lung scan?

A

The limitation of a ventilation-perfusion lung scan is that it may not be useful in patients with underlying lung disease.

20
Q

In which situations is a ventilation-perfusion lung scan used when CTPA is contraindicated?

A

A ventilation-perfusion lung scan is used when CTPA is contraindicated due to severe contrast allergy, renal dysfunction, or high risk from radiation.

21
Q

What is the recommended treatment for a small PE?

A

A small PE can go straight to a DOAC (direct oral anticoagulant) treatment.

22
Q

What is the recommended treatment for a large PE?

A

Initially, a large PE should be treated with heparin, usually sc low molecular weight heparin (eg Enoxaparin). Then, the patient can be converted to either warfarin or DOAC (eg Rivaroxaban, Dabigatran) for 3-6 months for the 1st event. Lifelong anticoagulation is recommended for 2nd events or persistent risk factors such as thrombophilia.

23
Q

What should be considered when deciding on anticoagulation therapy for a patient with PE?

A

Co-morbidities, contra-indications, patient preferences, and bleeding risk can be assessed with a scoring system (e.g. HASBLED). Special circumstances such as renal function, extremes of body weight, cancer thrombosis, and APLS should also be considered.

24
Q

What is the treatment for massive PE?

A

The treatment for massive PE includes intravenous fluids, IV heparin infusion, and consideration of thrombolysis if the patient has shock +/- right heart strain. Other options include surgical embolectomy and catheter fragmentation.

25
Q

What are some preventative measures for VTE (venous thromboembolism)?

A

Prophylactic low dose sc heparin, low dose Rivaroxaban after major joint surgery, venous compression stockings, pneumatic compression stockings, early mobilisation, and good hydration.