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Flashcards in thromboembolic disease Deck (36):
1

Substances which Embolize

Air
Amniotic Fluid
Foreign Bodies
Parasitic Eggs
Septic Emboli
Tumor Cell
MOST COMMON: Thrombus

2

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

3

steps in hemostasis

Vascular Injury (vasoconstriction)
Primary Hemostasis-Platelet Plug
Secondary Hemostasis-Clotting Cascade: Activate Fibrin
Fibrinolysis
Regulation

4

arteries vs veins

A:
Higher Pressure
More smooth muscle
Atherosclerosis

V:
More Distensible
Capacitance Vessels
Valves
Virchow’s Triad

5

arterial thromboembolism

Arterial Occlusive Disease
MI
Ischemic CVA
Mesenteric Ischemia
Vasculitides


6

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

7

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

8

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!

9

VTE dx

NOTORIOUSLY DIFICULT DIAGNOSIS
Findings depend of size of embolus and preexisting cardiopulmonary disease
Common signs and symptoms are not specific

10

VTE s/s

Dyspnea
Pain on inspiration
Tachypnea

Others:
Cough
Hemoptysis
Leg Pain
Tachycardia
Palpitations
Crackles
Homan’s Sign (pain with dorsiflexion of foot)

11

VTE ddx

Pneumonia
Lung Cancer
MI
COPD
Asthma
Traumatic Injury
Muscle Strain
Costochondritis
Inhalation Injury
Aortic Aneurysm
Congestive Heart Failure

12

virchow's triad

Stasis
Hypercoagulability
Endothelial Injury

13

virchow's triad: stasis

Prolonged immobility:

post orthopedic surgery,
Low Cardiac Output
Pregnancy
Post CVA
Travel (Air, Car)

14

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

15

virchow's triad: endothelial injury

Traumatic Injury
Recent Surgery
Previous Thrombosis

16

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 ?

17

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*

18

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

19

PE other lab findings

Serum Troponins, BNP typically elevated in PE

Not Useful in diagnosis, correlate with adverse outcomes

20

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

21

Westermark's Sign

prominent central pulmonary artery with local oligemia

Absence of vascular markings distal to engorged central pulmonary Vein

22

Hampton’s Hump

pleural based areas of increased opacity representing intraparenchymal hemorrhage

23

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

24

CT angiography Secondary Findings suggestive of PE

Abrupt arterial cutoff, asymmetrical blood flow, prolonged or slowed filling

25

Normal CT chest requires ??

initiation of empiric therapy (high pretest probability) or further testing (V/Q scan, etc.)

26

CT pics

saddle embolus: very concerning finding

27

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

28

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

29

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

30

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

31

PE/DVT preventable?

ARE preventable
Risk Assessment for Surgical Patients

32

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

33

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

34

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

35

PE/DVT interventions

Sequential Compression Devices (SCDs)

Medication:
Heparin
Lovenox

36

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