Post-operative Saddle Pulmonary Embolism with Extensive DVT: A Radiological and Clinical Perspective

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 Post-operative Saddle Pulmonary Embolism with Extensive DVT: A Radiological and Clinical Perspective

수술 후 광범위한 심부정맥혈전증을 동반한 안장 폐색전증: 방사선학적 및 임상적 고찰

Keywords: Saddle pulmonary embolism, deep venous thrombosis (DVT), postoperative complications, CT pulmonary angiography, IVC filter, Virchow's triad, massive PE, thrombolysis

Introduction

Pulmonary embolism (PE) is a critical medical emergency often stemming from deep venous thrombosis (DVT). It ranks as the third most common cause of cardiovascular death globally. Among its subtypes, saddle pulmonary embolism, where a thrombus straddles the bifurcation of the main pulmonary artery, poses an especially severe risk. This column presents an expert-level case analysis involving a 68-year-old woman who developed post-operative saddle PE accompanied by extensive DVT.

Case Summary

A 68-year-old female presented for elective repair of anterior abdominal wall hernias. Initial non-contrast CT of the abdomen and pelvis was unremarkable. The surgery was successful, and the patient was discharged in stable condition.

However, within days, she re-presented to the emergency department complaining of acute dyspnea and pleuritic chest pain. Initial chest radiography appeared normal. Subsequent CT pulmonary angiography revealed extensive bilateral PE, including a saddle embolus at the main pulmonary artery bifurcation. Right ventricular (RV) strain was evident.

Figure 1: Axial CTPA showing saddle embolism at the bifurcation of the main pulmonary artery.

Post-CT evaluation demonstrated DVT involving multiple lower extremity veins, prompting placement of an inferior vena cava (IVC) filter.

Figure 2: Coronal CT venography showing thrombi in the femoral and popliteal veins.


Imaging and Diagnosis

Chest Imaging Findings:

  • CTPA revealed filling defects in the right and left pulmonary arteries extending from the saddle area (RV:LV ratio >1).

  • Indications of right heart strain, including interventricular septal bowing.

Lower Limb Venography Findings:

  • CT venography demonstrated extensive bilateral DVT.

  • Involvement of femoral, popliteal, anterior, and posterior tibial veins was evident.


Figure 3: IVC filter placement noted on fluoroscopy following recurrent PE risk.


Pathophysiology

The case underscores Virchow's triad as the cornerstone of thrombus formation: venous stasis, endothelial injury, and hypercoagulability.

  • Post-operative immobility increases stasis.

  • Tissue handling during surgery contributes to endothelial injury.

  • Surgical stress and underlying comorbidities may enhance coagulation.

A thrombus originating from lower extremity veins can migrate to pulmonary arteries, particularly if proximal DVT is present, as observed in this patient.

Clinical Presentation and Challenges

PE is a diagnostic dilemma due to its broad symptom spectrum:

  • Common: Dyspnea, chest pain, hemoptysis

  • Severe: Syncope, shock, or sudden death

This patient initially presented with non-specific symptoms and a negative chest X-ray. Such cases highlight the diagnostic value of CTPA and the limited sensitivity of plain radiography.

Management

  1. Immediate Anticoagulation

    • LMWH or direct oral anticoagulants are preferred.

  2. Thrombolysis or Thrombectomy

    • Reserved for hemodynamically unstable or massive PE, as in this patient with saddle embolism and RV strain.

  3. IVC Filter Placement

    • Indicated due to extensive bilateral DVT and high recurrence risk.

  4. Supportive Care

    • Oxygen therapy, monitoring in the ICU, and echocardiographic surveillance.

Quiz

1. What is required to define a PE as "massive"?

(1) Large size

(2) Central location

(3) Hemodynamic instability

(4) All of the above

2. Does this patient show signs of RV strain?

(1) True

(2) False

3. What does Westermark's sign indicate on the chest radiograph?

(1) Focal hyper lucency

(2) Subsegmental atelectasis

(3) Peripheral wedge-shaped opacity

(4) Central pulmonary artery enlargement

4. Which vein was not affected by DVT in this case?

(1) External iliac

(2) Femoral

(3) Popliteal

(4) Anterior tibial

5. Which is not a benefit of IVC filters?

(1) Reduces PE incidence

(2) Reduces DVT incidence

(3) Useful in anticoagulation contraindications

Answer & Explanation

1. Correct Answer: (3) Explanation: Hemodynamic instability is the defining feature of massive PE, not merely size or location

2. Correct Answer: (1) Explanation: RV:LV ratio >1 and septal bowing suggest right heart strain.

3. Correct Answer: (1) Explanation: Westermark sign is focal hyperlucency due to reduced perfusion.

4. Correct Answer: (1) Explanation: Imaging showed all other veins had thrombi, except the external iliac.

5. Correct Answer: (2) Explanation: IVC filters do not reduce DVT incidence; they may increase it due to stasis.

References

[1] Andreoli JM, et al. Inferior vena cava filter-related thrombus/deep vein thrombosis. Semin Intervent Radiol. 2016;33(2):101-104.

[2] Cho ES, et al. CT venography for DVT using low tube voltage. Korean J Radiol. 2013;14(2):183-193.

[3] Chung J, Owen RJ. Using IVC filters to prevent PE. Can Fam Physician. 2008;54(1):49-55.

[4] Girard P, et al. Diagnosis of PE in patients with DVT. Am J Respir Crit Care Med. 2001;164(6):1033-1037.

[5] Kushner A, et al. Virchow Triad. In: StatPearls. 2023. https://www.ncbi.nlm.nih.gov/books/NBK539697/

[6] Moore AJE, et al. Imaging of acute pulmonary embolism. Cardiovasc Diagn Ther. 2018;8(3):225-243.

[7] Morrone D, et al. Acute PE: Clinical Picture. Korean Circ J. 2018;48(5):365-381.

[8] Sekhri V, et al. Management of massive and nonmassive PE. Arch Med Sci. 2012;8(6):957-969.

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