Week 2: Pulmonary embolism

Question 1

venous thromboembolic (VTE) diseases summary

Answer 1

type-hemodynamics-treament

1. DVT- stable -anticoagulation
2. Non-massive PE-stable-anticoag
3. Massive PE-unstable-thrombolysis
   - massive PE can cause right heart failure, long term consequence is chronic pulmonary HTN

Question 2

Risk factors for PE

Answer 2

Virchow's triad
1. Venous stasis
-CHF, immobility, obesity, surgery, trauma
2. Endothelial injury
-hx of VTE, trauma, catheters
3. hypercoaguable states
-inherited, acquired
MAJOR RISK FACTORS
-major surgery, lower extremities fractures, pregnancy, h/o VTE, malignancy, varicose veins, prolonged immobility

Question 3

Pathophysiology of PE: respiratory consequences

Answer 3

1. decreased perfusion from occlusion of pulmonary artery. Leads to increased dead space with decreased CO2 excretion
   - compensation: hyperventilation, causes hypocapnia
2. Decreased perfusion leads to decreased surfactant synthesis
   - more difficult for alveoli to stay open, more prone to collapse
   - hypocapnia may cause bronchioconstriction of small airways
   - hypoxemia and atelectasis
3. widened A-a gradient

Question 4

Cardiac/hemodynamic consequences of PE

Answer 4

1. increased pulmonary vascular resistance due to occlusion of pulmonary artery
   - usually not significant unless large
2. pulmonary HTN and RV failure
   - if PE is large enough and cardiopulmonary reserve is poor
   - RV dilation compresses LV, leads to decrease CO and hypotension, syncope or death
3. release of mediators may result in vasoconstriction and increase in pulmonary vascular resistance

Question 5

Possible outcomes of PE

Answer 5

• usually not ischemia infart because dual perfusion from bronchial and pulmonary
• Most PEs come from DVTs
  1. fragmentation of emboli+clot lysis
• no changes
  2. reorganization and partial recanalization (~3 months)
  3. infarction leading to scar formation

Question 6

Symptoms and signs of PE

Answer 6

SYMPTOMS
-acute dyspnea
-pleuritic chest pain
-hemoptysis
-anxiety, cough, palpitation
-sycope, rare
SIGNS
-tachypnea
-tachycardia, S4, accentuated P2
-fever, friction rub
-signs of DVT
-evidence of R heart failure

Question 7

Radiographic findings

Answer 7

• X-ray: usually normal. May see prominent PA, pleural effusion, decreased perfusino (westermark’s sign), wedge shaped infarct (Hamptom’s hump)
• CT w/ contrast: FIRST LINE. appear as filing defect and may find vessel cut off

Question 8

D-dimer test for PE

Answer 8

• degradation product of cross-linked fibrin
• good sensitivity but low specificity
• a negative D dimer rules out PE but a positive can’t diagnose

Question 9

Diagnosis of DVT

Answer 9

-Doppler Ultrasound

Question 10

Treatment for PE

Answer 10

1. anticoagulation to prevent reoccurrence of PE
   - goal is PTT 2x normal achieved within 24 hours
   - if stable; LMWH or fondaparonox
   - if unstable: IV heparin
   - followed by oral coumadin for 3-6 months
2. Thrombolytics to clot bust
   - tPA, urokinase

Question 11

Pulmonary HTN

Answer 11

• when mPAP is greater than 25 mmHg
• characteristic feature: remodeling of pulmonary vasculature
• plexogenic lesion: intralumenal growth of fibrous network, from endothelial or fibroblasts in the intimalbasement
• thrombogenic arteriopathy: clot organization