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 (RV) (i.e. RV width > LV width)
- straightening or leftward bulging of the interventricular septum
- enlargement of the pulmonary trunk
Contrast reflux into the azygos vein, via the superior vena cava, 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 heart pressures.