Massive bilateral pulmonary embolism

CT pulmonary angiogram

• Main Pulmonary Artery: Extensive central intraluminal filling defect straddling the bifurcation of the main pulmonary artery (saddle embolus).
• Right Pulmonary Artery: Thrombus present with almost complete occlusion, extending into the lobar branches.
• Left Pulmonary Artery: Non-occlusive clot present, extending into the lingular branch.
• Right Ventricle: Dilated and wider than the left ventricle, indicating RV dysfunction and right heart strain.

Discussion

• Pathophysiology: Acute pulmonary embolism is characterized by intraluminal filling defects within the pulmonary arterial circulation. A saddle pulmonary embolus is defined as a thrombus positioned across the bifurcation of the main pulmonary artery.
• Imaging Findings: The study demonstrates an extensive saddle embolus with bilateral extension and markedly asymmetric thrombotic burden, producing near-complete obstruction of the right pulmonary artery.
• Clinical Context: The patient's history of oral contraceptive use is a known risk factor for thrombosis.
• Hemodynamic Assessment: While saddle pulmonary emboli represent a substantial central thrombotic burden, morphology alone does not define hemodynamic severity. Clinical risk stratification relies on hemodynamic status and evidence of right ventricular dysfunction and myocardial injury. CT pulmonary angiography serves a dual role in establishing the diagnosis and assessing features of right heart strain 1,3.