Chronic carotid revascularization - SLICE Worldwide 2021

Replay Day 2 - Slice WW 2021 - Stroke Game 6

Chronic carotid revascularization – its pros, cons and the technique

Presentations of case resolutions in the form of a “serious game”. Step by step, from the emergency call to the resolution on high fidelity silicon models in the angiosuite, the members of the SLICE Academy will work along with faculty members to solve these real cases reconstitutions. 

DIAGNOSIS:

CTP in chronic asymptomatic ICA occlusion:

• Tmax delayed 
• MTT, CBV, CBF – normal

CTP in chronic symptomatic ICA occlusion (hemodynamic changes due to hypoperfusion):

• Tmax delayed 
• MTT increased
•  CBV and CBF decreased (but less pronounced than in typical acute stroke)

Sometimes severe stenosis (near-occlusion) can present as an occlusion, so to be sure, you should confirm the diagnosis in DSA. DSA may reveal “string sign” in that cases.

Be aware of carotid “pseudostring sign” from vasa vasorum collaterals in case of total chronic carotid occlusion (its presence is a positive predictive value of successful recanalization). 

SYMPTOMS:

Patients may be: asymptomatic, periodically symptomatic with hemispheric neurological symptoms (symptoms induced during physical effort) or constantly symptomatic.

Stress-test with acetazolamide (mimicking physical effort) is usually performed under scintigraphy (quantitative method), but may also be used during MRI imaging.

Patient may have cognitive impairment in neuropsychological testing due to focal cognitive deficits attributed to affected hemisphere.

TECHNIQUE:

- Start with 3D-angiography of the stump

- If there is vasa vasorum supplying the lumen of ICA at some point above the occlusion, perform the intramural dissection: 

• you plug the BCG in the stump of ICA, then you start crossing the lesion with diagnostic 5F catheter and long microwire with microcatheter on inflated BCG (it gives you extra support)*

*procedure is safe until this moment (no connection to the patent lumen of ICA above = no risk of distal emboli neither reperfusion injury)

• you have to re-enter to the proper lumen of ICA* 

*continuing with intramural dissection on the level of ophthalmic branch of ICA can jeopardize cerebral and ophthalmic supply – re-entry point should be below the ophthalmic segment

- once you manage to enter the proper lumen of ICA, aspire with small 3cc syringe to see whether you have blood backflow and then do microangiography (on BCG deflated) to confirm the proper position of the microcatheter in the true lumen 

- push 300 cm wire into the MCA and do the over-the-wire-exchange (remove microcatheter and 5F catheter)

- perform  “full metal jacket” reconstruction of ICA on bare wire (with overlap of the stents, under inflated BCG) :

• start with the antegrade implantation of normal carotid stents up to the skull base 
• once you placed your stents at the level of cervical portion of ICA, go up with BCG to not block the flow through ECA any more
• perform PTA of the channel at the level of re-entry point 
• do the retrograde intracranial reconstruction with flow diverters (another option is the usage of carotid coronary stents)
• once you overlap all the stents, you perform the control run (on BCG deflated)

- evaluate the patency of intracranial vessels and confirm good apposition of the stents by performing vaso-CT

Note: if it is possible to stay from the beginning in the true lumen, it is even better (no need for re-entry, lower rate of re-occlusion, better chance of reendothelialization of created channel).

CRUCIAL POINTS:

The keys are:

• qualification of the patient to the treatment (hypoperfusion without infarct core)
• preloading with drugs (patients prepared on heparin during 10 days prior the intervention, DAPT or cangrelor iv. during the procedure)
• postoperative treatment : medications + blood pressure surveillance (maintenance of low blood pressure after the procedure* and antiplatelet therapy)

*before the revascularization high blood pressure is recommended

Please note that there is a need for further investigation and safety evaluation of the procedure.