Venous Thromboembolic Disease

VENOUS THROMBOEMBOLIC DISEASE
by:R. Duncan Hite, MD
Section on Pulmonary and Critical Care Medicine

Venous Thromboembolic Disease

* Venous thrombosis - ~ 5 million pts yearly
+ Most caused by inadequate prophylaxis in hospitalized pts
* 10 % suffer pulmonary embolism ~ 500,000
* ~ 1% of all hospitalized pts have PE
* Contributes to 6 % of all hospital deaths
* ~ 125,000 deaths annually from PE
+ 3rd most common cardiovascular cause of death (MI, CVA)
+ Most deaths occur early – PREVENTION IS KEY!!
* Diagnosis of PE made in < 30% when contributes to death; < 10% if incidental

Case studies
Venous Thromboembolic Disease
Epidemiology

* 85 - 90% of PE pts have DVT risk factors
* 90-95% of PEs arise from lower ext. DVT
* Defined DVT Risk Factors: (Virchow’s Triad)
o Venous stasis - CHF, Immobility, Age > 70, Travel, Obesity, Recent surgery (4 weeks) or hospitalization (6 mos)
o Venous Injury - Prior DVT/PE, LE Trauma/Surgery
# LE trauma or surgery - Very high (50+%)
# Major surgery - (5 - 8%)
o Hypercoaguability - Cancer, Pregnancy, Nephrotic Syndrome, Hyperhomocysteinemia, Factor V Leyden mutation, Deficiency of Protein C/S or ATIII, Anti Phospholipid Ab, HITTS, Smoking

Pulmonary Hypertension Hemodynamic Effects
Deep Venous Thrombosis
Diagnosis
* Venography - remains the “gold standard”
+ Pitfalls: Difficult to perform, expensive, contrast load, DVT
* Compression Ultrasound (Sonography, Duplex and Color Doppler)
+ Criteria: echogenicity, noncompressibility, distension, free floating thrombus, absence of Doppler waveform, Abnormal color image
+ Accuracy:
# Symptomatic Patients: Sensitivity = 90-100%, Specificity = 95-100%
# High Risk Asymptomatic: Sensitivity = 50-80%, Specificity = 95-100%
* Impedance Plethysmography
* Radionuclide Venography (Indium-111)
* MRI - increasing popularity and utilization, includes deep pelvic veins

Deep Venous Thrombosis Prevention
* Orthopedic Surgery
o LMWH or Coumadin (INR 2.0 - 3.0) beginning preoperatively or immediately postoperatively. Adjusted dose SQ Heparin is an acceptable alternative but more complex.
o Adjuvant use of mechanical devices may add additional benefit. May be sufficient as primary prophylaxis for TKR if used optimally.
o Low dose SQ Hep, Aspirin, IPC alone are not recommended (less effective).
o Duration:
+ minimum of 7-10 days
+ Post Discharge Prophylaxis: 4-6 weeks for high risk patients
* General Surgery (including Urologic)
o Prophylaxis with SQHep, LMWH, ES or IPC
+ Moderate Risk - minor procedure with a risk factor or 40-60 yo, major procedures and <40
+ High Risk - minor procedure with risk factors or >60, major procedures with risk factors or age >40.
+ Increased Risk of Bleeding - use ES or IPC
o Combination therapy: very high risk - multiple risk factors
o Postdischarge Prophylaxis: selected very high risk pts
* Gynecologic Surgery
o Major surgery for benign disease
# SQ Hep BID, LMWH, IPC, continue for several days post op
o Major surgery for malignancy
# SQ Hep TID, Combination AC/Mech, high dose LMWH
* Neurosurgery
o Intracranial Surgery
# IPC or ES, Low dose SQHep or LMWH may be acceptable
# Combination IPC or ES with SQHep or LMWH in high risk

Deep Venous Thrombosis Prevention
* Trauma
o LMWH as soon as possible
o IPC or ES until LMWH started
* Acute Spinal Cord Injury
o LMWH recommended
o Low dose SQHep, ES or IPC are less effective
o Combination Mechanical/anticoagulant may be acceptable
o Continue throughout rehabilatation
* Medical (Cancer, CHF, Bedrest, MI, CVA…)
o Low dose SQ Hep or LMWH
o IPC if anticoagulation contraindicated

PE SIGNS AND SYMPTOMS
Symptoms
* Dyspnea - 80%
* Chest pain - 70%
* Cough - 50%
* Apprehension - 50%
* Hemoptysis - 30%

Signs
* Tachycardia - 60%
* Tachypnea - 70%
* Fever - 60%
* Clinical DVT - 30%

Pulmonary Embolism Diagnosis
* Chest x-ray - nonspecific abnormalities in most; normal early
+ Westermark's sign and Hampton's hump uncommon
* Arterial blood gas – hypoxemia is common
+ 15 - 20% will not manifest hypoxemia (i.e. normal A-a gradient)
* ECG – nonspecific changes typically
+ S1Q3T3 pattern in massive PE with RV strain
+ helpful in evaluating other causes of chest pain

PE – V/Q LUNG SCAN
* Radiolabeled Xenon inhaled for ventilation and radiolabeled Technetium for perfusion
* Safe
* Not very specific
* Not very useful if pre-existing lung disease

Pulmonary Embolism Diagnosis - V/Q Scan
Pulmonary Embolism
Diagnosis - Pulmonary Arteriogram
* Remains “gold standard” for Dx of PE
* Expensive
* Low morbidity and mortality
o Mortality < 0.1%
o Major morbidity < 0.5%
o Pulmonary Hypertension not a contraindication
Pulmonary Embolism
Diagnosis - Pulmonary Arteriogram
Lobar Defect
Segmental Defect
Pulmonary Embolism
Diagnosis - Chest CT
* Accurate for segmental or larger PE
+ Sensitivity 85 - 95% (Overall 50-60%)
+ Specificity 90 - 100%
* Accuracy depends on interpreter
+ Large Inter-interpreter variability
+ Reduced accuracy with less experience
* Significant contrast load ~ 65% of PA gram
* Similar expense to Pulmonary Arteriogram
* Can identify other pulmonary etiologies
Pulmonary Emboli Diagnosis - MRA
Venous Thromboembolism Treatment
Continuous IV Heparin:
Heparin-Induced Antibodies
Venous Thromboembolism Treatment
Low Molecular Weight Heparins:
Venous Thromboembolism Outpatient LMWH
Enoxaparin sodium
Unfractionated heparin
Venous Thromboembolism
Treatment
Synthetic Heparins:
Fondaparinux (Arixtra)
Oral anticoagulation (Coumadin)
Inferior Vena Cava Filter

VENOUS THROMBOEMBOLIC DISEASE.ppt