Neurovascular Cases

What’s the diagnosis?

Copious clot throughout the left common carotid artery and internal carotid artery. Despite multiple thrombectomy passes, clot continued to propagate in the vessel and anterograde (forward) blood flow was halted.

Right common carotid artery injection demonstrates brisk cross-filling from the right-to-left hemispheres via the ACOMM artery, suggesting sluggish anterograde flow in the left carotid artery.

Left common carotid artery injection shows copious clot (the cloudy white material) throughout the common carotid artery, the internal carotid artery, and also intracranially.

Differential Diagnosis

  1. Paradoxical embolus, meaning clot that passes from the venous circulation into the arterial circulation could explain this presentation. A deep venous thrombosis could propagate from the legs to both the left common carotid artery and the lungs.
  2. Hypercoagulable states, such as antiphospholipid antibody syndrome, Protein C deficiency, Factor V Leiden, malignancy, etc.


  • In this case the most likely pathophysiology is that the patient developed a deep venous thrombosis that traveled from the venous system to the heart and then, paradoxically, into the arterial system.
  • Paradoxical emboli can occur in the presence of a patent foramen ovale, which is an embryonic defect, or hole, in the intra-arterial septum of the heart. A patent foramen ovale is persistent in about 25% of the general population, and it is associated with cryptogenic strokes.

What's your treatment plan?

  • Removal of clot in the supraaortic vessels is performed via aspiration thrombectomy either with a pump aspiration system or with manual syringe aspiration.
  • In a situation when clot continues to obstruct anterograde (forward) flow despite multiple thrombectomy passes, it is reasonable to consider placing stents to both pin active thrombus against the vessel walls, and to prop open the vessel.

In this case, multiple thrombectomy passes were performed in the left internal and common carotid arteries. Unfortunately clot continued to propagate and shut down the vessel. Telescoping stents were placed from the high cervical segment of the internal carotid artery down to the common carotid artery and anterograde flow was restored. The patient was found to have a large patent foramen ovale.


CT angiogram chest demonstrates large pulmonary embolus.