Saddle pulmonary embolism commonly refers to a large pulmonary embolism that straddles the bifurcation of the pulmonary trunk, extending into the left and right pulmonary arteries.
If large enough, it can completely obstruct both left and right pulmonary arteries resulting in right heart failure and, unless treatment is prompt, death.
With such extensive embolic burden, signs of right heart strain are usually present and include:
- dilatation of the right ventricle (i.e. RV width > LV width)
- straightening or leftward bulging of the intraventricular septum
- enlargement of the pulmonary trunk
Contrast reflux into the azygos vein and hepatic veins via the inferior vena cava is a controversial sign of RV strain, as it often occurs in the absence of raised right-sided pressures.
- 1. Wu AS, Pezzullo JA, Cronan JJ et-al. CT pulmonary angiography: quantification of pulmonary embolus as a predictor of patient outcome-initial experience. Radiology. 2004;230 (3): 831-5. doi:10.1148/radiol.2303030083 - Pubmed citation