thromboembolic disease Flashcards
Substances which Embolize
Air Amniotic Fluid Foreign Bodies Parasitic Eggs Septic Emboli Tumor Cell MOST COMMON: Thrombus
purpose and components of hemostatic system
Purpose: Prevent blood loss due to vascular Injury
Components:
Formed Elements: Cells-Platelets, Monocytes, RBCs
Plasma Proteins-Clotting Factors, Fibrinolytic Factors, Inhibitors
Vessel Wall: Epithelium vonWillibrand Factor (vWF) Collagen Tissue Factor
steps in hemostasis
Vascular Injury (vasoconstriction) Primary Hemostasis-Platelet Plug Secondary Hemostasis-Clotting Cascade: Activate Fibrin Fibrinolysis Regulation
arteries vs veins
A:
Higher Pressure
More smooth muscle
Atherosclerosis
V: More Distensible Capacitance Vessels Valves Virchow’s Triad
arterial thromboembolism
Arterial Occlusive Disease MI Ischemic CVA Mesenteric Ischemia Vasculitides
venous thromboembolism (VTE)
PE DVT Superior Vena Cava Obstruction Chronic ThromboEmbolic Pulmonary HTN (CTEPH) Dural Sinus Thrombosis Portal Vein Thrombosis Vasculitis-Bechet’s, Granulomatosis with polyangiitis Mesenteric Vein Occlusion
Pulmonary venous thromboembolism
aka Pulmonary Embolism (PE)
3rd leading cause of death among hospital pts
Often not recognized ante mortem (before death)
less than 10% of pts receive specific tx
thrombus
Most common etiology of emboli
Most Common Site of Origin
Deep Veins of the Lower Extremities (i.e. popliteal, common iliac)
Found in 50-70% of pts with symptomatic PE
Can Form Anywhere!
VTE dx
NOTORIOUSLY DIFICULT DIAGNOSIS
Findings depend of size of embolus and preexisting cardiopulmonary disease
Common signs and symptoms are not specific
VTE s/s
Dyspnea
Pain on inspiration
Tachypnea
Others: Cough Hemoptysis Leg Pain Tachycardia Palpitations Crackles Homan’s Sign (pain with dorsiflexion of foot)
VTE ddx
Pneumonia Lung Cancer MI COPD Asthma Traumatic Injury Muscle Strain Costochondritis Inhalation Injury Aortic Aneurysm Congestive Heart Failure
virchow’s triad
Stasis
Hypercoagulability
Endothelial Injury
virchow’s triad: stasis
Prolonged immobility:
post orthopedic surgery, Low Cardiac Output Pregnancy Post CVA Travel (Air, Car)
virchow’s triad: hypercoagulability
Medications: Oral Contraception, Hormone Replacement Malignancy Genetic: *Factor V Leiden* Protein C/S/antithrombin III deficiency/dysfunction prothrombin gene mutation hyperhomocysteinemia antiphospolipid antibodies
virchow’s triad: endothelial injury
Traumatic Injury
Recent Surgery
Previous Thrombosis
PE clinical findings: EKG
Abnormal in about 70% of pts with PE
Most Common Finding: Sinus Tachycardia (most common!!) and Nonspecific SR and T wave changes
Right Heart Strain: RBBB, Right Axis Deviation, S1Q3T3
prominent S wave in 1, Q wave in 3, T wave in 3 ?
PE clinical findings: ABG
Usually Respiratory Alkalosis
Abnormal pO2 and Alveolar-arterial O2 gradient
NOT DIAGNOSTIC
Profound Hypoxia with Normal Chest X-ray THINK PE
PE lab findings: D-dimer
Fibrin Degradation product
Sensitivity 95-97%, Specificity 45%
NO diagnostic threshold established for positive result: may be elevated in inflammation/trauma/infection
*BEST INFORMATION WHEN NEGATIVE (SN-OUT: good at ruling out when negative)
Negative : less than 500mcg/L, Likelihood ratio 0.11-0.13
PE other lab findings
Serum Troponins, BNP typically elevated in PE
Not Useful in diagnosis, correlate with adverse outcomes
PE imaging
Chest Xray
Useful to rule out other etiologies: pneumonia, CHF, etc
Most Frequent findings:
Atelectasis, Parenchymal Infiltrates, Pleural Effusion
Uncommon Findings
Westermark Sign
Hampton’s Hump
Westermark’s Sign
prominent central pulmonary artery with local oligemia
Absence of vascular markings distal to engorged central pulmonary Vein
Hampton’s Hump
pleural based areas of increased opacity representing intraparenchymal hemorrhage
PE clin findings: CT angiography
Requires IV contrast dye (don’t want to give to renal failure pts)
Primary finding suggestive of PE:
Intravascular filling defect
Very sensitive for central vascular filling defects
~80% sensitive, 96% specific
15-20% false negative rate
CT angiography Secondary Findings suggestive of PE
Abrupt arterial cutoff, asymmetrical blood flow, prolonged or slowed filling
Normal CT chest requires ??
initiation of empiric therapy (high pretest probability) or further testing (V/Q scan, etc.)
CT pics
saddle embolus: very concerning finding
PE clin findings: Ventilation Perfusion (V/Q) scan
Perfusion assessed by injection of radiolabeled albumin injected into venous circulation
Ventilation assessed by records distribution of inhaled radio labeled gas
The two images are compared, looking for defects
Criteria for assessment are complex, confusing and not standardized
Ventilation Perfusion (V/Q) scan reported in terms of ??
probability: low, intermediate, and high
PIOPED1;
If low, 14% probability of PE
Combined with low pretest probability, lowers risk to 4%
If indeterminate, low or intermediate probability, further testing required
Venous Thrombosis Studies: Venous Ultrasonography
positive test ??
Incompressibility of common femoral or popliteal veins
In a patient with appropriate symptoms
Positive predictive value 97%
Negative Test: Full compressiblity at both vessels
Negative Predictive value 98%
Less accurate in distal thrombi, recurrent thrombi, and asymptomatic patients
Wells Criteria: scoring systems to assess PE Risk
3: Clinical Signs and symptoms of DVT:
Unilateral edema, and pain with palpation
3: Alternative Diagnosis Less likely than PE
1.5: Pulse >100bpm
1: Immobilization >3days in past 4 wks
1: Previous DVT/PE
1: Hemoptysis
1: Cancer (With Tx w/in past 6 mo. or Palliation)
Total >4pts: Imaging warranted
Total
PE/DVT preventable?
ARE preventable
Risk Assessment for Surgical Patients
pts @ High risk for PE/DVT
Major orthopedic procedure/arthroplasty Abdominal/pelvic cancer undergoing surgery recent spinal cord injury major trauma w/in previous 90days >3 intermediate criteria
pts @ Intermediate Risk for PE/DVT
Ambulation less than 2x/day
Active Inflammation/infection/malignancy, Major Non orthopedic surgery
h/o VTE, CVA
Central venous access/PICC line
BMI greater than 30
OCP/HRT use
Immobilization more than 72hrs Hypercoagulable state
nephrotic syndrome
burns, cellulites’, varicose veins, paresis
Systolic Heart Failure
COPD exacerbation
pts @ low risk for PE/DVT
Minor procedures, age younger than 40 without addition risk factors
Ambulatory with expected length of stay less than 24hrs
PE/DVT interventions
Sequential Compression Devices (SCDs)
Medication:
Heparin
Lovenox
pulmonary VTE tx
Heparin: binds ATIII, accelerates inact of thrombin factor 10a, 9a
thrombolytic therapy:
Thrombolytic Therapy
Streptokinase, urokinase, alteplase(tPA)
Systemic or catheter directed tPA
IVC filter: short term, Can increase PE risk in the first two years of therapy
Must be Removed
embolectomy: Rare, Reserved for critically ill patients after unsuccessful thrombolytic therapy
