Where does a saddle embolism occur?

Location of Saddle Embolism

A saddle embolism occurs at the aortoiliac bifurcation (where the abdominal aorta divides into the two common iliac arteries) in arterial circulation, or at the pulmonary artery bifurcation (where the main pulmonary artery divides into right and left pulmonary arteries) in venous thromboembolism. 1

Arterial Saddle Embolism (Aortic)

The term "saddle embolus" most commonly refers to an embolus that lodges at the aortoiliac bifurcation, straddling the division point like a saddle. 1

Key Anatomic Features:

• Emboli characteristically lodge at arterial branch points where vessel caliber diminishes 1
• The aortoiliac bifurcation represents the terminal division of the abdominal aorta into the right and left common iliac arteries 2, 3
• Most aortic saddle emboli (94%) occur below the renal arteries 3

Clinical Significance:

• Produces bilateral lower-limb ischemia due to simultaneous obstruction of both iliac arterial systems 1
• May be associated with reversible paraplegia from spinal cord ischemia 1
• Carries a high mortality rate (reported 30-33% overall) 2, 4, 3
• 96% originate from cardiac sources, most commonly atrial fibrillation 2

Pulmonary Saddle Embolism

In the pulmonary circulation, a saddle embolus lodges at the bifurcation of the main pulmonary artery into the right and left pulmonary arteries. 5

Distinguishing Features:

• Represents a type of central pulmonary embolism involving the pulmonary artery bifurcation 5
• Associated with right heart strain and hemodynamic compromise 5
• Requires different treatment approach than peripheral arterial saddle emboli 5

Clinical Pitfall

Do not confuse the location based on context: The term "saddle embolism" without qualification typically refers to aortoiliac bifurcation in peripheral vascular disease discussions 1, but refers to pulmonary artery bifurcation when discussing venous thromboembolism 5. The anatomic principle is identical—emboli lodge at major bifurcation points where vessel caliber decreases—but the vascular territory differs entirely 1.