Flashcards in *DVT + PE Deck (52):
What is a thrombus?
A blood clot that forms in the veins
What is an embolus?
Anything that passes through the blood vessels until it reaches a vessel that is too small to let it pass
What is a thromboembolus?
obstruction of a blood vessel by a blood clot that has become dislodged from another site in the circulation
What is a DVT?
Formation of thrombi within the lumen of the vessels that make up the deep venous system
What is a distal vein thrombosis?
A DVT of the calves
What is a proximal vein thrombosis?
DVT of the popliteal vein or the femoral vein
What is venous thromboembolis? (VTE)
A collective name used to describe both a DVT and a PE
What is Virchow's triad?
(triad of conditions that predispose to thrombus formation)
What are the 4 things that cause endothelial injury?
Venous valvular damage
Trauma or surgery
What are the 4 things that cause circulatory status?
Left ventricular dysfunction
Immobility or paralysis
Venous insufficiency or varicose veins
Venous obstruction from tumour, obesity or pregnancy
What are the 6 things that can cause a hyper coagulable state?
Pregnancy and peripartum period
What are 6 exposing risk factors (acute conditions or trauma, surgery) that are risk factors for VTE?
Acute medical illness
Acute heart failure
Acute respiratory failure
Centra venous catheterisation
What are the 11 predisposing risk factors (Patient characteristics) that are risk factors for VTE?
History of VTE
Chronic heart failure
Immobility or paresis
Pregnancy/ permpartum period
Inherited or acquired thrombophilia
What are the 2 overlapping exposing and predisposing risk factors for VTE?
What is an unprovoked VTE?
An idiopathic VTE - there are no identifiable causes for it (compared to a provoked VTE)
Do provoked or unprovoked VTE have a higher recurrence rate?
What is a venous blood clot mainly composed of? (2)
What are the known consequences of a VTE?
Risk of recurrent VTE
Post-thrombotic syndrome (PTS)
Chronic thromboembolic pulmonary hypertension (CTEPH)
Reduced quality of life
How common is post thrombotic syndrome?
Occurs in nearly one-third of patients within 5 years after idiopathic DVT (common)
What are the symptoms/ signs of post thrombotic syndrome?
Varicose collateral veins
(thought to be associated with DVT-induced damage to valves in the deep veins and valvular reflex leading to venous hypertension)
What is chronic thromboembolic pulmonary hypertension?
A serious (But relatively rare) complication of PE
A condition where the original embolic material is replaced over time with fibrous tissue that is incorporated into the intimate and media of the pulmonary arteries
This material may occlude the pulmonary artery leading to pulmonary resistance and ultimately right heart failure
Symptoms of chronic thromboembolic pulmonary hypertension?
Initially = asymptomatic followed by progressive dyspnoea and hypoxaemia
What are the original investigations for a patient with suspected VTE?
Pre-test probability calculated (using Wells score/ modified wells score for PE)
Depending on probability, imaging
What is D-dimer?
A breakdown product of cross linked fibrin
What is D-dimer used for?
To rule out a VTE - if you suspect a VTE, perform this and if it is negative, they require no further testing
What scoring system is used in Tayside to assess the risk of a DVT being present pre-test?
What are the factors in the wells test that give a score?
+1 for all of the following:
Active drug injector
Calf swelling greater than 3cm compared to other calf
Collateral superficial veins (non-varicose)
Pitting oedema (confined to symptomatic lef)
Swelling of entire leg
Localised pain along distribution of deep venous system
Paraslysis, paresis, or recent cast immobilisation of lower extremities
Recently bed ridden for greater than 3 days or major surgery in past month
-2 if alternative diagnosis at least as likely
0 or less = low probability
1-2 = moderate
3 or more = high
If the patient has a low wells score, what investigations should be carried out?
No imaging if negative
If the patient has a moderate/ high wells score, what investigations should be carried out?
Need imaging regardless of D-dimer
Negative imaging and positive D-dimer requires repeat imaging
What is the modified wells score used for?
To assess the risk of PE
What is the modified wells score for PE?
Clinical signs of DVT = 3 points
PE most likely diagnosis = 3 points
HR greater than 100 = 1.5 points
Immobilisation at least 4 days or surgery within 4 weeks = 1.5
Previous diagnosis of DVT/ PE = 1.5
Haemoptysis = 1
Malignancy within 6 months = 1
Score of less than or equal to 4 makes PE unlikely
Score of greater than 4 makes PE likely
What does the revised Geneva score assess?
The risk of having had a PE
What is the revised geneva score?
Risk factors/ symptoms:
age greater than 65 = 1 point
Previous DVT/ PE = 3 points
Surgery or leg fracture in last month = 2 points
Active malignant condition = 2 points
Unilateral limb pain = 3 points
Haemoptysis = 2 points
HR 75 - 94 = 3 points
HR greater than or equal to 95 = 5 points
Pain on lower limb deep venous palpation AND unilateral oedema = 4 points
0 - 3 points = low risk (D-dimer negative = no more investigations)
4 - 10 oints = intermediate risk (if D-dimer negative consider stopping investigation but likely need to exclude)
High risk = Imaging regardless of D-dimer
What imaging should be performed if indicated for a PE?
If chest x-ray is normal, do a V/Q scan
If radiation should be avoided/ leg is swollen, consider doing an US to look for a DVT
If chest x-ray is abnormal or a massive PE is expected, do a CTPA
What can a chest x-ray show in a PE?
Pleural effusions and occasionally infarcts
What scan is performed to look for a PE in pregnancy?
V/Q scan but perfusion part only is performed, presuming ventilation is normal
How to treat DVT and PE?
Pharmacological agents (anticoagulation, thrombolysis, analgesia)
Mechanical interventions (graduated compression stockings, IVC filters)
Screening (cancer, thrombophilia)
What type of anticoagulation is used to treat VTE patients?
Low molecular weight heparin (then anticoagulate with warfarin for 3 months or with heparin if the patient has cancer until their treatment finishes (always at least 6 months)) - stop heparin once INR is greater than 2
How long do patients with provoked/ unprovoked VTE get warfarrin for?
3 months (in unprovoked VTE assess the risks and benefits for continuing anticaogulation for prevention of VTE recurrence)
How long do patients with active cancer get heparin for after a VTE?
6 months before being reassessed for continued treatment
What can be considered instead of using warfarin to anticaogulate?
NOACs - new oral anticoagulants (don't need INR monitored and lower bleeding rate but don't have an antidote so can't be reversed)
What are 4 examples of NOACs?
How long are NOACs used standardly to prevent reoccurrence of VTE?
6 months (compared with normally 3 for warfarin)
When are NOACs tending to be used in comparison to warfarin?
When patient is a drug user or there is associated cancer
When is heparin stopped in patients with VTE?
When INR is greater than 2 (keep going with heparin if the patient has cancer)
When are patient with a DVT treated with thrombolysis?
If they have symptomatic ileofemoral DVT symptoms less than 14 days duration and good functional status and a life expectancy of 1 year or more with a low risk of bleeding (catheter thrombolysis)
When are patients with a PE considered for thrombolysis?
Consider pharmacological systemic thrombolytic therapy in patients with PE and haemodynamic instability - large clot (if the patient is haemodynamically stable, do not give pharmacological thrombolytic therapy)
Why are compression stockings used in patients with DVT?
To prevent post thrombotic sydnrome
What type of compression stockings are used for DVT?
Class 2 european standard compression stockings
When are compression stockings worn?
As soon as possible after diagnosis (when swelling is reduced and no contraindications) - worn during the day for at least 2 years post thrombosis
Why have compression stockings been taken off the guidelines?
Due to their negative effect in arterial disease (consider them if the patient does not have this)