Venous Thromboembolism Flashcards
Prevention of Fatal PE
- Recognize patients at risk of VTE and institute prophylactic treatment
- Recognize and treat DVT to prevent PE
- Recognize first episode of PE and initiate therapy to prevent recurrent, fatal PE
DVT and PE
- Most episodes of DVT begin in calf veins
- Without anticoagulation, ~1/4 of calf vein DVTs progress to proximal (above the knee) DVT
- Without anticoagulation, almost 1/2 of proximal DVTs progress to PE
- Without Rx, ~1/3 of episodes of PE are fatal
Factors Leading to Venous Thrombosis
• Virchow’s Triad
– Venous trauma (endothelial injury)
– Stasis (abnormal blood flow)
– Hypercoagulability
Risk Factors for VTE
– History of VTE
– Hypercoagulability
– Immobility
– Congestive Heart Failure
– Cancer
– Advanced age
– Recent surgery
– Trauma
– Pregnancy
– OCA and estrogen (HRT) use
VTE Prophylaxis
- Early ambulation
- Sequential compression devices (SCDs)
- Anticoagulation
– Subcutaneous unfractionated heparin, low molecular weight heparin, or fondaparinux
Physical Examination
- Only a difference in calf diameters was of potential value for ruling in DVT
- Accordingly, further diagnostic testing is required to confirm or exclude the diagnosis of DVT
-ultrasound
Why is Diagnosis of PE so difficult?
- The two most common symptoms of PE: dyspnea and chest pain have multiple other more common causes.
- A given episode of PE may present as one of three different clinical syndromes
Three Steps to Diagnose PE
- Step one: Suspect PE – In patients with chest pain, dyspnea or syncope: Are the clinical findings suggestive of one of the syndromes of PE?
- Step two: Estimate probability of PE
– Apply one of the clinical prediction models: Wells or Geneva Model
• Step three: Confirm or R/O PE
– If D-Dimer is negative and probability is low or moderate: PE ruled out
– If chest CT is positive: Treat for PE
Syndromes of Acute PE
- Acute cor pulmonale*
- Acute, unexplained dyspnea
- Pulmonary infarction
*Cor pulmonale is defined as an alteration in the structure and function of the right ventricle caused by a primary disorder of the respiratory system.
Cor Pulmonale
Syndromes of Acute PE Acute Cor Pulmonale
- Symptoms: shock, collapse, syncope
- Exam: hypotension, distended neck veins
- EKG: S1Q3T3 or incomplete RBBB
- CXR: normal
- ABGs: decreased pO2, decreased pCO2
- Echocardiogram: severe right ventricular dysfunction
- Differential DX: Acute Myocardial infarction (AMI)
Syndromes of Acute PE Acute Unexplained Dyspnea
• Symptoms
-Dyspnea +/- anxiety
• Physical Exam
-Tachypnea, clear lungs
• EKG
-Usually normal
• Chest X-ray
-Normal
• Blood gases
-Decreased pO2/pCO2
•Differential DX:
-CHF, hyperventilation
Syndromes of Acute PE Pulmonary Infarction
• Symptoms
– Acute pleuritic pain
– Dyspnea, +/- hemoptysis
• Physical Exam
– Tachypnea
– Crackles, wheezes or rub
• CXR
– consolidation in periphery of lung; may have pleural effusion
• EKG
- normal
• ABG
- pO2 and pCO2 may be decreased or may be “normal”
•Differential DX: Pneumonia
D-dimer For The Exclusion of PE
- D-Dimer (fibrin fragments) measured by quantitative rapid ELISA test
- Positive = > 500 ng/ml
- Sensitivity for PE = 97%
- Specificity for PE = 41%
Diagnostic Pathways For Suspected PE
- High probability by Wells or Geneva criteria: Proceed to chest CT
- Low or moderate probability: Obtain D- dimer If D-dimer positive: chest CT If D-dimer negative: no therapy
Ventilation/Perfusion (VQ) Scans As Substitute For Chest CT
- Pregnant or women in child-bearing age
- Patients with normal or near-normal chest x-ray
- Abnormal renal function—risk of contrast media with chest CT-angiogram
Treatment of Acute PE
“Prophylactic” Treatment
- Anticoagulation
- Inferior vena caval interruption Definitive Treatment
- Thrombolytic therapy
- Pulmonary embolectomy
- Patients with acute PE who are hemodynamically stable will survive if further episodes of PE are prevented.
- They require prophylactic therapy with anticoagulants (or IVC interruption if unable to anticoagulate)
Treatment of Acute PE Anticoagulant Therapy
• LMW heparin or fondaparinux
– 5 days of therapy followed by warfarin
• February 2016 guidelines
– NOACs preferred over warfarin
– Dabigatran, rivaroxaban, apixaban, edoxaban
New Oral anticoagulants Direct Thrombin Inhibitors (DTIs) and Factor Xa Inhibitors
• Advantages over warfarin
– Monitoring not needed
– Fixed dose
– More rapid onset/offset
– Wider therapeutic index/Less intracranial hemorrhage
• Disadvantages
– More expensive
– Antidotes? (idarucizumab, andexanet)
– Degree of anticoagulation
Treatment of Acute PE Duration of Oral Anticoagulant Therapy
• Three Months
– Pts with a transient (reversible) risk factor for VTE
– “Provoked” versus “unprovoked” VTE
• Three Months or Long Term
– Patients with unprovoked (idiopathic) VTE
• Long Term
– Cancer patients (until cancer has resolved)
– Second episode of unprovoked VTE
Contraindications To Thrombolytic Therapy
- Major internal bleeding within 6 months
- Intracranial disease
- Recent operation or organ biopsy
- Occult blood on stool examination
- Severe uncontrolled hypertension
- Severe hepatic or renal impairment
- Pregnancy or lactation
Treatment of VTE: IVC Filters
• Major indication
– Contraindication to anticoagulation
• Others indications controversial
Treatment of PE Complicated by Shock
Approximately 5-10% of PE patients develop shock. Their mortality with anticoagulant therapy is approximately 30%. In addition to anticoagulation, PE patients in shock should receive one of the three following therapies:
- THROMBOLYTIC THERAPY with r-tPA (recombinant tissue plasminogen activator) may be considered in patients who have no contraindications to thrombolytic therapy. The major complication is severe bleeding. Intracerebral hemorrhage occurs in 2-3% of patients.
- PULMONARY EMBOLECTOMY - This can be considered in a hospital that is staffed to perform emergency cardiac surgery. The ideal candidate is a young patient without associated heart or lung disease who has a contraindication to thrombolytic therapy.
- CATHETER FRAGMENTATION OF EMBOLI - there are case reports that this may be beneficial in some patients. Some combine this with thrombolytic therapy.
