Pulmonary embolism

Acute pulmonary embolism can be a life threatening condition and is the 3rd leading cause of cardiovascular mortality in the US. This article focuses on the assessment and treatment of acute embolism. Discussion regarding the imaging findings and sequelae of chronic pulmonary embolism can be found here.


Deep venous thrombosis and pulmonary embolism are two manifestations of venous thromboembolic disease. Risk factors include:

  • Major trauma, surgery, lower extremity joint replacement
  • Oral contraceptives or hormone replacement therapy (varies according to type), pregnancy (highest in the 3 months post-partum)
  • Solid organ and hematologic malignancies
  • Infection
  • In children: central venous catheters

Acute pulmonary embolism causes death due to pressure overload and inhibiting gas exchange. PE causes an inflammatory reaction with release of thromboxane A2 and serotonin.

Pulmonary embolism - circle of death.png

Circulatory cascade of death:

  1. Increased pulmonary vascular resistance causes RV dilatation
  2. RV myocyte stretch/wall tension causes neurohormonal inotropic and chronotropicstimulation (can sometimes result in PE-induced myocarditis).
  3. Leftward bowing of the interatrial septum causes desynchronized ventricular contraction and may lead to development of right bundle-branch block
  4. LV filling is impeded in early diastole and may cause collapse of cardiac output
  5. Lowered cardiac output results in decreased systemic blood pressure and RV (and LV) coronary perfusion.
  6. V/Q mismatch contributes to hypoxemia. Right to left shunting via a PFO or ASD can also cause severe hypoxemia.

Post-pulmonary embolism syndrome (PPS)- long term complication of PE with the most severe manifestation being chronic thromboembolic pulmonary hypertension (CTEPH).


Thrombolysis for Pulmonary Embolism and Risk of All-Cause Mortality, Major Bleeding, and Intracranial Hemorrhage[1]-

ULTIMA RCT- Ultrasound accelerates thrombolysis for the treatment of acute PE. 10-20mg TPA over 24 hours. No difference in hospital stay.

SEATTLE II multicenter trial- very stringent exclusion criteria- RV/LV ratio improved


PERFECT multi-center registry[2] - no significance between standard catheter directed thrombolysis vs ultrasound assisted thrombolysis (EKOS) catheter infusion. "These data also support the use of lowdose thrombolytic infusion through standard catheters for patients with submassive PE without the need for high-cost USAT catheters."

Radiographic findings

See here.

Pre-procedure evaluation

Adapted from: Society of Interventional Radiology Position Statement on Catheter-Directed Therapy for Acute Pulmonary Embolism[3]
Category Characteristics Short term mortality rate Treatment
Low risk Absence of right heart strain and systemic

arterial hypotension

Approx <1-2% Anticoagulation

(Intermediate risk)

Presence of right heart dysfunction in the setting of normal blood pressure 5.6% clinical deterioration within 7 days, at least 3% 30 day mortality rate Optimal strategy is uncertain:
Low risk submassive- +RV or dysfunction or +cardiac biomarkers
High risk submassive - if +RV dysfunction on imaging and +cardiac biomarkers. Consider reperfusion.

(High risk)

sustained systemic arterial hypotension defined by a systolic blood pressure < 90 mmHg for at least 15 minutes or requiring inotropic support Approx 25-65% Anticoagulation, consider systemic thrombolysis, catheter directed thrombolysis, and/or surgical embolectomy

Risk Stratification:

2014 ESC guidelines on the diagnosis and management of acute pulmonary embolism.[4]
2014 ESC guidelines on the diagnosis and management of acute pulmonary embolism.[4]


Needs a multidisciplinary approach for management.

Mechanical thrombectomy- pulmonary embolism thrombectomy via aspiration catheter

Catheter directed thrombolysis (CDT) and Ultrasound assisted thrombolysis (USAT)- infusion of TPA via either infusion catheters (multi-sidehole pig tail catheter or Unifuse catheter) or EkoSonic (BTG corporation) catheters

Surgical thrombectomy-

Post-procedure care/Complications

Systemic thrombolysis - major hemorrhage risk about 9%, intra-cranial hemorrhage approximately 1.5%.

Catheter directed thrombolysis- 2.4% major complication rate, most of which were associated with AngioJet.

  1. Chatterjee S, Chakraborty A, Weinberg I, et al. Thrombolysis for pulmonary embolism and risk of all-cause mortality, major bleeding, and intracranial hemorrhage: a meta-analysis. JAMA. 2014;311(23):2414-21.https://jamanetwork.com/journals/jama/fullarticle/1881311
  2. Kuo WT, Banerjee A, Kim PS, et al. Pulmonary Embolism Response to Fragmentation, Embolectomy, and Catheter Thrombolysis (PERFECT): Initial Results From a Prospective Multicenter Registry. Chest. 2015;148(3):667-673. https://www.sciencedirect.com/science/article/pii/S0012369215506442?via%3Dihub
  3. Kuo WT, Sista AK, Faintuch S, et al. Society of Interventional Radiology Position Statement on Catheter-Directed Therapy for Acute Pulmonary Embolism. J Vasc Interv Radiol. 2018;29(3):293-297.
  4. 4.0 4.1 Konstantinides SV, Torbicki A, Agnelli G, et al. 2014 ESC guidelines on the diagnosis and management of acute pulmonary embolism. Eur Heart J. 2014;35(43):3033-69, 3069a-3069k.

Contributing Authors

Kevin Liu