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Pulmonary Embolism
Jennifer R. Buckley, MD, MBA; Brandt C. Wible, MD
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KEY FACTS

  • Terminology

    • Preprocedure

      • Procedure

        • Outcomes

          TERMINOLOGY

          • Definitions

            • Pulmonary embolism (PE): Embolized blood clot within pulmonary artery (PA) causing obstruction and altered lung perfusion
              • Estimated annual incidence: 1/1,000
              • 3rd most common cause of cardiovascular death in USA per year
              • Deep vein thrombosis (DVT) is most common cause
              • Variable symptoms
                • Asymptomatic
                • Chest pain, dyspnea, cough, palpitations
                • Hypotension, syncope, cardiogenic shock, death
            • Right ventricular (RV) dysfunction: Dilation, impaired function and ischemia that occurs in setting of acute PE as result of increased afterload
              • Present in 45% of patients with PE
              • Associated with increased mortality (25% if normotensive, up to 65% if hypotensive)
              • If untreated, ultimately progresses to cause decreased left ventricular (LV) output, cardiogenic shock, and death
              • Imaging
                • CTA: Increased RV:LV ratio (> 0.9), reflux of contrast into hepatic veins
                • Echo: RV dilatation, impaired contractility
              • Laboratory: Evidence of myocardial necrosis [elevated troponin or brain natriuretic peptide (BNP)]
            • Chronic thromboembolic pulmonary hypertension (CTEPH): Subtype of pulmonary hypertension (PH) that develops from nonresolution of PE
              • Develops in ~ 4% of patients with PE
              • Presence of obstructive fibrotic thromboembolic material in major pulmonary vessels
              • Causes progressive, severe right heart failure
            • Catheter-directed thrombolysis (CDT): Infusion of thrombolytics through catheter positioned directly in PA
            • Mechanical thrombectomy (MT): Mechanical disruption and removal of thrombus via suction without thrombolytics
          • Risk Stratification

            • European Society of Cardiology (ESC) risk stratification (2019)
              • Low risk: No shock, signs of RV dysfunction, or elevated cardiac biomarkers (troponin/BNP)
              • Intermediate risk: RV dysfunction, no shock or hypotension
                • Intermediate-low risk: Without elevated cardiac biomarkers (troponin/BNP)
                • Intermediate-high risk: With elevated cardiac biomarkers (troponin/BNP)
              • High risk: RV dysfunction with shock or hypotension
            • PE Severity Index (PESI) Score
              • Escalating levels of severity (class I to class V), corresponding to escalating 30-day mortality risk (1-25%)
              • Calculated with demographic and clinical information rather than imaging/labs
                • Demographic: Age, sex
                • Comorbidities: Cancer, heart failure, chronic lung disease
                • Clinical findings: Pulse, blood pressure, respiratory rate, temperature, mental status, O₂ saturations
              • Simplified PESI score (sPESI)
                • Simplified scoring splitting into 2 groups
                  • 0 points: Low risk (< 1% 30-day mortality), can potentially be treated outpatient
                  • > 1 point: Elevated risk, can be further stratified with full PESI
                • Points awarded for: Age > 80 years, history of cancer/CHF/COPD, pulse > 110, systolic blood pressure (SBP) < 100, or O₂ saturations < 90%
              • Massive/submassive: Terminology falling out of favor, not descriptive enough to risk stratify or estimate mortality
          • Systemic Therapy

            • Anticoagulation
              • Options include warfarin (vitamin K antagonist), novel oral anticoagulants (NOACs), such as rivaroxaban, apixaban, dabigatran, or low-molecular-weight heparin
                • Warfarin therapy most cost effective but requires regular interval monitoring of patient's international normalized ratio (INR)
                • NOACs do not require therapeutic monitoring but tend to be more expensive
              • Patient's renal function, comorbidities, and preference should be taken into account when selecting anticoagulation regimen
            • Systemic thrombolysis
              • Peripheral administration of tissue plasminogen activator (tPA)
                • Variable dosing strategies, but 50 mg commonly used
              • Significantly reduces mortality compared to anticoagulation alone in high-risk PE
              • Increased risk of major bleeding, including intracranial hemorrhage
                • May be contraindicated in certain patients
          • Catheter-Directed Therapies

            • Generally reserved for patients with intermediate-high or high-risk PE
            • CDT
              • Placement of catheters into pulmonary arteries for direct tPA infusion, usually 1 mg of tPA/hour over 24-48 hours
              • Can be done ± US assistance
                • No clear consensus of benefit
              • ULTIMA trial (2014): CDT superior to anticoagulation in improving RV dilation
              • SEATTLE II study (2015): Decreased RV dilation, PH, and thrombus burden with fewer instances of intracranial hemorrhage
            • MT
              • Multiple commercially available devices for direct aspiration &/or mechanical disruption of clot
              • Do not require use of thrombolytics, and thus have decreased risk of major bleeding
              • Indigo System (Penumbra Inc)
                • Aspiration catheter (multiple options up to 12 Fr) with continuous vacuum
                • Also used for peripheral arterial and venous systems
                • EXTRACT-PE trial (2021): Significant reduction in RV:LV ratio, low major adverse events
              • FlowTriever (Inari Medical)
                • Large-bore aspiration system (16-24 Fr) with negative suction-locking syringe
                  • Optional coaxial component for clot disruption
                • Wible et al (2019): Significant reduction of mean PA pressure with good safety and survival profile
                • Buckley et al (2021): Improved mortality and decreased ICU length of stay for those with central PE of elevated risk (PESI 4/5 and ESC intermediate-high/high risk)
          • Treatment of Low-Risk Pulmonary Embolism

            • CHEST guidelines: Isolated subsegmental PE may not require treatment in low-risk patients
            • Low clinical risk patients (sPESI 0) diagnosed in ER may not require hospital admission in order to initiate anticoagulation

          PREPROCEDURE

          • Indications

            • Contraindications

              • Preprocedure Imaging

                • Getting Started

                  PROCEDURE

                  • Patient Position/Location

                    • Procedure Steps

                      • Findings and Reporting

                        • Alternative Procedures/Therapies

                          POST PROCEDURE

                          • Things to Do

                            • Things to Avoid

                              OUTCOMES

                              • Problems

                                • Complications

                                  • Expected Outcomes

                                    Selected References

                                    1. Buckley JR et al: In-hospital mortality and related outcomes for elevated risk acute pulmonary embolism treated with mechanical thrombectomy versus routine care. J Intensive Care Med. 8850666211036446, 2021
                                    2. Sista AK et al: Indigo aspiration system for treatment of pulmonary embolism: results of the EXTRACT-PE trial. JACC Cardiovasc Interv. 14(3):319-29, 2021
                                    3. Bryce YC et al: Pathophysiology of right ventricular failure in acute pulmonary embolism and chronic thromboembolic pulmonary hypertension: a pictorial essay for the interventional radiologist. Insights Imaging. 10(1):18, 2019
                                    4. Wible BC et al: Safety and efficacy of acute pulmonary embolism treated via large-bore aspiration mechanical thrombectomy using the Inari FlowTriever Device. J Vasc Interv Radiol. 30(9):1370-5, 2019
                                    5. Behravesh S et al: Pathogenesis of thromboembolism and endovascular management. Thrombosis. 2017:3039713, 2017
                                    6. Goktay AY et al: Endovascular treatment of thrombosis and embolism. Adv Exp Med Biol. 906:195-213, 2017
                                    7. Lou BH et al: A meta-analysis of efficacy and safety of catheter-directed interventions in submassive pulmonary embolism. Eur Rev Med Pharmacol Sci. 21(1):184-98, 2017
                                    8. Teleb M et al: Ultrasound-assisted catheter-directed thrombolysis: a novel and promising endovascular therapeutic modality for intermediate-risk pulmonary embolism. Angiology. 68(6):494-501, 2017
                                    9. Bajaj NS et al: Catheter-directed treatment for acute pulmonary embolism: systematic review and single-arm meta-analyses. Int J Cardiol. 225:128-39, 2016
                                    10. Biteker M et al: Thrombolysis in pulmonary embolism: full-dose, low-dose, or catheter-directed thrombolysis? Am J Emerg Med. 34(8):1720-1, 2016
                                    11. Dilektasli AG et al: Catheter-directed therapy in acute pulmonary embolism with right ventricular dysfunction: a promising modality to provide early hemodynamic recovery. Med Sci Monit. 22:1265-73, 2016
                                    12. Kaymaz C et al: Ultrasound-assisted catheter-directed thrombolysis in high-risk and intermediate-high-risk pulmonary embolism: results from a single-center cohort. Angiology. 68(5):433-40, 2016
                                    13. Liang NL et al: Comparative outcomes of ultrasound-assisted thrombolysis and standard catheter-directed thrombolysis in the treatment of acute pulmonary embolism. Vasc Endovascular Surg. 50(6):405-10, 2016
                                    14. Monteleone PP et al: Multidisciplinary pulmonary embolism response teams and systems. Cardiovasc Diagn Ther. 6(6):662-7, 2016
                                    15. Sadiq I et al: Risk factors for major bleeding in the SEATTLE II trial. Vasc Med. 1358863X16676355, 2016
                                    16. Sag S et al: Catheter-directed ultrasound-accelerated thrombolysis may be life-saving in patients with massive pulmonary embolism after failed systemic thrombolysis. J Thromb Thrombolysis. 42(3):322-8, 2016
                                    17. Sharifi M: Systemic Full dose, half dose, and catheter directed thrombolysis for pulmonary embolism. When to use and how to choose? Curr Treat Options Cardiovasc Med. 18(5):31, 2016
                                    18. Tafur AJ et al: Catheter-directed treatment of pulmonary embolism: a systematic review and meta-analysis of modern literature. Clin Appl Thromb Hemost. 20(11):1431-40, 2016
                                    19. Teman NR et al: Massive pulmonary embolism treated with catheter therapy and extracorporeal membrane oxygenation. Heart Surg Forum. 19(6):E303-E305, 2016
                                    20. Kuo WT et al: Pulmonary embolism response to fragmentation, embolectomy, and catheter thrombolysis (PERFECT): initial results from a prospective multicenter registry. Chest. 148(3):667-73, 2015
                                    21. Nykamp M et al: Safety and efficacy of ultrasound-accelerated catheter-directed lytic therapy in acute pulmonary embolism with and without hemodynamic instability. J Vasc Surg Venous Lymphat Disord. 3(3):251-7, 2015
                                    22. Piazza G et al: A prospective, single-arm, multicenter trial of ultrasound-facilitated, catheter-directed, low-dose fibrinolysis for acute massive and submassive pulmonary embolism: the SEATTLE II study. JACC Cardiovasc Interv. 8(10):1382-92, 2015
                                    23. Kucher N et al: Randomized, controlled trial of ultrasound-assisted catheter-directed thrombolysis for acute intermediate-risk pulmonary embolism. Circulation. 129(4):479-86, 2014
                                    24. Kuo WT: Endovascular therapy for acute pulmonary embolism. J Vasc Interv Radiol. 23(2):167-79.e4; quiz 179, 2012
                                    25. Sobieszczyk P: Catheter-assisted pulmonary embolectomy. Circulation. 126(15):1917-22, 2012
                                    26. Kandarpa K et al. Handbook of Interventional Radiologic Procedures. Lippincott, Williams & Wilkins, 2011
                                    27. Agnelli G et al: Acute pulmonary embolism. N Engl J Med. 363(3):266-74, 2010
                                    28. Kuo WT et al: Catheter-directed therapy for the treatment of massive pulmonary embolism: systematic review and meta-analysis of modern techniques. J Vasc Interv Radiol. 20(11):1431-40, 2009
                                    29. Weiss CR et al: CT pulmonary angiography is the first-line imaging test for acute pulmonary embolism: a survey of US clinicians. Acad Radiol. 13(4):434-46, 2006
                                    30. Sacks D et al: Society of Interventional Radiology clinical practice guidelines. J Vasc Interv Radiol. 14(9 Pt 2):S199-202, 2003
                                    Related Anatomy
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                                    Related Differential Diagnoses
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                                    References
                                    Tables

                                    Tables

                                    KEY FACTS

                                    • Terminology

                                      • Preprocedure

                                        • Procedure

                                          • Outcomes

                                            TERMINOLOGY

                                            • Definitions

                                              • Pulmonary embolism (PE): Embolized blood clot within pulmonary artery (PA) causing obstruction and altered lung perfusion
                                                • Estimated annual incidence: 1/1,000
                                                • 3rd most common cause of cardiovascular death in USA per year
                                                • Deep vein thrombosis (DVT) is most common cause
                                                • Variable symptoms
                                                  • Asymptomatic
                                                  • Chest pain, dyspnea, cough, palpitations
                                                  • Hypotension, syncope, cardiogenic shock, death
                                              • Right ventricular (RV) dysfunction: Dilation, impaired function and ischemia that occurs in setting of acute PE as result of increased afterload
                                                • Present in 45% of patients with PE
                                                • Associated with increased mortality (25% if normotensive, up to 65% if hypotensive)
                                                • If untreated, ultimately progresses to cause decreased left ventricular (LV) output, cardiogenic shock, and death
                                                • Imaging
                                                  • CTA: Increased RV:LV ratio (> 0.9), reflux of contrast into hepatic veins
                                                  • Echo: RV dilatation, impaired contractility
                                                • Laboratory: Evidence of myocardial necrosis [elevated troponin or brain natriuretic peptide (BNP)]
                                              • Chronic thromboembolic pulmonary hypertension (CTEPH): Subtype of pulmonary hypertension (PH) that develops from nonresolution of PE
                                                • Develops in ~ 4% of patients with PE
                                                • Presence of obstructive fibrotic thromboembolic material in major pulmonary vessels
                                                • Causes progressive, severe right heart failure
                                              • Catheter-directed thrombolysis (CDT): Infusion of thrombolytics through catheter positioned directly in PA
                                              • Mechanical thrombectomy (MT): Mechanical disruption and removal of thrombus via suction without thrombolytics
                                            • Risk Stratification

                                              • European Society of Cardiology (ESC) risk stratification (2019)
                                                • Low risk: No shock, signs of RV dysfunction, or elevated cardiac biomarkers (troponin/BNP)
                                                • Intermediate risk: RV dysfunction, no shock or hypotension
                                                  • Intermediate-low risk: Without elevated cardiac biomarkers (troponin/BNP)
                                                  • Intermediate-high risk: With elevated cardiac biomarkers (troponin/BNP)
                                                • High risk: RV dysfunction with shock or hypotension
                                              • PE Severity Index (PESI) Score
                                                • Escalating levels of severity (class I to class V), corresponding to escalating 30-day mortality risk (1-25%)
                                                • Calculated with demographic and clinical information rather than imaging/labs
                                                  • Demographic: Age, sex
                                                  • Comorbidities: Cancer, heart failure, chronic lung disease
                                                  • Clinical findings: Pulse, blood pressure, respiratory rate, temperature, mental status, O₂ saturations
                                                • Simplified PESI score (sPESI)
                                                  • Simplified scoring splitting into 2 groups
                                                    • 0 points: Low risk (< 1% 30-day mortality), can potentially be treated outpatient
                                                    • > 1 point: Elevated risk, can be further stratified with full PESI
                                                  • Points awarded for: Age > 80 years, history of cancer/CHF/COPD, pulse > 110, systolic blood pressure (SBP) < 100, or O₂ saturations < 90%
                                                • Massive/submassive: Terminology falling out of favor, not descriptive enough to risk stratify or estimate mortality
                                            • Systemic Therapy

                                              • Anticoagulation
                                                • Options include warfarin (vitamin K antagonist), novel oral anticoagulants (NOACs), such as rivaroxaban, apixaban, dabigatran, or low-molecular-weight heparin
                                                  • Warfarin therapy most cost effective but requires regular interval monitoring of patient's international normalized ratio (INR)
                                                  • NOACs do not require therapeutic monitoring but tend to be more expensive
                                                • Patient's renal function, comorbidities, and preference should be taken into account when selecting anticoagulation regimen
                                              • Systemic thrombolysis
                                                • Peripheral administration of tissue plasminogen activator (tPA)
                                                  • Variable dosing strategies, but 50 mg commonly used
                                                • Significantly reduces mortality compared to anticoagulation alone in high-risk PE
                                                • Increased risk of major bleeding, including intracranial hemorrhage
                                                  • May be contraindicated in certain patients
                                            • Catheter-Directed Therapies

                                              • Generally reserved for patients with intermediate-high or high-risk PE
                                              • CDT
                                                • Placement of catheters into pulmonary arteries for direct tPA infusion, usually 1 mg of tPA/hour over 24-48 hours
                                                • Can be done ± US assistance
                                                  • No clear consensus of benefit
                                                • ULTIMA trial (2014): CDT superior to anticoagulation in improving RV dilation
                                                • SEATTLE II study (2015): Decreased RV dilation, PH, and thrombus burden with fewer instances of intracranial hemorrhage
                                              • MT
                                                • Multiple commercially available devices for direct aspiration &/or mechanical disruption of clot
                                                • Do not require use of thrombolytics, and thus have decreased risk of major bleeding
                                                • Indigo System (Penumbra Inc)
                                                  • Aspiration catheter (multiple options up to 12 Fr) with continuous vacuum
                                                  • Also used for peripheral arterial and venous systems
                                                  • EXTRACT-PE trial (2021): Significant reduction in RV:LV ratio, low major adverse events
                                                • FlowTriever (Inari Medical)
                                                  • Large-bore aspiration system (16-24 Fr) with negative suction-locking syringe
                                                    • Optional coaxial component for clot disruption
                                                  • Wible et al (2019): Significant reduction of mean PA pressure with good safety and survival profile
                                                  • Buckley et al (2021): Improved mortality and decreased ICU length of stay for those with central PE of elevated risk (PESI 4/5 and ESC intermediate-high/high risk)
                                            • Treatment of Low-Risk Pulmonary Embolism

                                              • CHEST guidelines: Isolated subsegmental PE may not require treatment in low-risk patients
                                              • Low clinical risk patients (sPESI 0) diagnosed in ER may not require hospital admission in order to initiate anticoagulation

                                            PREPROCEDURE

                                            • Indications

                                              • Contraindications

                                                • Preprocedure Imaging

                                                  • Getting Started

                                                    PROCEDURE

                                                    • Patient Position/Location

                                                      • Procedure Steps

                                                        • Findings and Reporting

                                                          • Alternative Procedures/Therapies

                                                            POST PROCEDURE

                                                            • Things to Do

                                                              • Things to Avoid

                                                                OUTCOMES

                                                                • Problems

                                                                  • Complications

                                                                    • Expected Outcomes

                                                                      Selected References

                                                                      1. Buckley JR et al: In-hospital mortality and related outcomes for elevated risk acute pulmonary embolism treated with mechanical thrombectomy versus routine care. J Intensive Care Med. 8850666211036446, 2021
                                                                      2. Sista AK et al: Indigo aspiration system for treatment of pulmonary embolism: results of the EXTRACT-PE trial. JACC Cardiovasc Interv. 14(3):319-29, 2021
                                                                      3. Bryce YC et al: Pathophysiology of right ventricular failure in acute pulmonary embolism and chronic thromboembolic pulmonary hypertension: a pictorial essay for the interventional radiologist. Insights Imaging. 10(1):18, 2019
                                                                      4. Wible BC et al: Safety and efficacy of acute pulmonary embolism treated via large-bore aspiration mechanical thrombectomy using the Inari FlowTriever Device. J Vasc Interv Radiol. 30(9):1370-5, 2019
                                                                      5. Behravesh S et al: Pathogenesis of thromboembolism and endovascular management. Thrombosis. 2017:3039713, 2017
                                                                      6. Goktay AY et al: Endovascular treatment of thrombosis and embolism. Adv Exp Med Biol. 906:195-213, 2017
                                                                      7. Lou BH et al: A meta-analysis of efficacy and safety of catheter-directed interventions in submassive pulmonary embolism. Eur Rev Med Pharmacol Sci. 21(1):184-98, 2017
                                                                      8. Teleb M et al: Ultrasound-assisted catheter-directed thrombolysis: a novel and promising endovascular therapeutic modality for intermediate-risk pulmonary embolism. Angiology. 68(6):494-501, 2017
                                                                      9. Bajaj NS et al: Catheter-directed treatment for acute pulmonary embolism: systematic review and single-arm meta-analyses. Int J Cardiol. 225:128-39, 2016
                                                                      10. Biteker M et al: Thrombolysis in pulmonary embolism: full-dose, low-dose, or catheter-directed thrombolysis? Am J Emerg Med. 34(8):1720-1, 2016
                                                                      11. Dilektasli AG et al: Catheter-directed therapy in acute pulmonary embolism with right ventricular dysfunction: a promising modality to provide early hemodynamic recovery. Med Sci Monit. 22:1265-73, 2016
                                                                      12. Kaymaz C et al: Ultrasound-assisted catheter-directed thrombolysis in high-risk and intermediate-high-risk pulmonary embolism: results from a single-center cohort. Angiology. 68(5):433-40, 2016
                                                                      13. Liang NL et al: Comparative outcomes of ultrasound-assisted thrombolysis and standard catheter-directed thrombolysis in the treatment of acute pulmonary embolism. Vasc Endovascular Surg. 50(6):405-10, 2016
                                                                      14. Monteleone PP et al: Multidisciplinary pulmonary embolism response teams and systems. Cardiovasc Diagn Ther. 6(6):662-7, 2016
                                                                      15. Sadiq I et al: Risk factors for major bleeding in the SEATTLE II trial. Vasc Med. 1358863X16676355, 2016
                                                                      16. Sag S et al: Catheter-directed ultrasound-accelerated thrombolysis may be life-saving in patients with massive pulmonary embolism after failed systemic thrombolysis. J Thromb Thrombolysis. 42(3):322-8, 2016
                                                                      17. Sharifi M: Systemic Full dose, half dose, and catheter directed thrombolysis for pulmonary embolism. When to use and how to choose? Curr Treat Options Cardiovasc Med. 18(5):31, 2016
                                                                      18. Tafur AJ et al: Catheter-directed treatment of pulmonary embolism: a systematic review and meta-analysis of modern literature. Clin Appl Thromb Hemost. 20(11):1431-40, 2016
                                                                      19. Teman NR et al: Massive pulmonary embolism treated with catheter therapy and extracorporeal membrane oxygenation. Heart Surg Forum. 19(6):E303-E305, 2016
                                                                      20. Kuo WT et al: Pulmonary embolism response to fragmentation, embolectomy, and catheter thrombolysis (PERFECT): initial results from a prospective multicenter registry. Chest. 148(3):667-73, 2015
                                                                      21. Nykamp M et al: Safety and efficacy of ultrasound-accelerated catheter-directed lytic therapy in acute pulmonary embolism with and without hemodynamic instability. J Vasc Surg Venous Lymphat Disord. 3(3):251-7, 2015
                                                                      22. Piazza G et al: A prospective, single-arm, multicenter trial of ultrasound-facilitated, catheter-directed, low-dose fibrinolysis for acute massive and submassive pulmonary embolism: the SEATTLE II study. JACC Cardiovasc Interv. 8(10):1382-92, 2015
                                                                      23. Kucher N et al: Randomized, controlled trial of ultrasound-assisted catheter-directed thrombolysis for acute intermediate-risk pulmonary embolism. Circulation. 129(4):479-86, 2014
                                                                      24. Kuo WT: Endovascular therapy for acute pulmonary embolism. J Vasc Interv Radiol. 23(2):167-79.e4; quiz 179, 2012
                                                                      25. Sobieszczyk P: Catheter-assisted pulmonary embolectomy. Circulation. 126(15):1917-22, 2012
                                                                      26. Kandarpa K et al. Handbook of Interventional Radiologic Procedures. Lippincott, Williams & Wilkins, 2011
                                                                      27. Agnelli G et al: Acute pulmonary embolism. N Engl J Med. 363(3):266-74, 2010
                                                                      28. Kuo WT et al: Catheter-directed therapy for the treatment of massive pulmonary embolism: systematic review and meta-analysis of modern techniques. J Vasc Interv Radiol. 20(11):1431-40, 2009
                                                                      29. Weiss CR et al: CT pulmonary angiography is the first-line imaging test for acute pulmonary embolism: a survey of US clinicians. Acad Radiol. 13(4):434-46, 2006
                                                                      30. Sacks D et al: Society of Interventional Radiology clinical practice guidelines. J Vasc Interv Radiol. 14(9 Pt 2):S199-202, 2003