Why is PE Important?
2. Life threatening
3. Can be challenging to diagnose
PE on CT
Large thrombus blocks blood supply. The IV contrast does not reach the parts of the tissue that is blocked off from the PE.
Why do PE's Have Different Clinical Presentations?
There is a huge variety of locations for a PE to occur, and a large variety of the size of PEs. Small PEs typically produce less symptoms than large ones.
The right side of the heart can act like a blender and mash up a clot into varying sized pieces, which may become stuck in the lungs.
Origins of PE
90% originate from the deep veins in the legs.
The other 10% can occur from upper extremity veins, renal veins, pelvic veins, or the heart.
They do NOT come from superficial veins such as varicose veins or saphenous veins.
Signs and Symptoms of a DVT
Red, swollen, warm, tender leg.
Many patients do not have symptoms. You need to investigate further by performing an ultrasound or looking for a D-Dimer.
Pathophysiologic Response to a PE
Bilateral perfusion defects
Infarction (although the tissue is more resistant to infarction due to the dual blood supply of both the pulmonary circulation and bronchial artery)
Abnormal gas exchange
Diagnostic Evaluation of PE
History (HPI, PMHx, Risk Factors)
Chest X-Rays, ECG
Doppler U/S of Legs
Risk Factors for PE
Surgery (within last 3 months)
A radiologic sign which consists of a shallow wedge-shaped opacity in the periphery of the lung with its base against the pleural surface.
Can indicate a PE and may also be associated with pleural effusion.
A radiographic sign seen in 2% of PE cases. It results as a combination of the dilation of the pulmonary arteries proximal to the embolus and the collapse of the distal vasculature creating the apparearance of a sharp cut off on chest radiography.
Most Common Cause of False + D-Dimer
Estimating Clinical Probability of PE
Ventilation/Perfusion (V/Q) Scan
Patient breaths in radiolabelled particles and also has IV radiolabelled dye administered. You then look for unmatched defecits where areas are well-ventilated but there is no perfusion.
In the picture, A is the scan after inhalation of the particles. B is the scan after the radiolabelled dye is administered. You can see in A that the entire lung is well-coated, however in B there are areas where the blood is not well-perfused.
V/Q is useful if the Well's Score is high or if it is low, but not intermediate.
Signs of Massive PE
Tachycardia, tachypnea, hypotension, increased JVP, R-sided S3
Treatment of PE
Initial and chronic anticoagulation
IVC filter for select indications
For massive PE... Systemic thrombolysis, catheter-directed thrombolysis, or surgical embelectomy.