Carotid angioplasty and stenting (CAS): pre-op planning and essential steps
Presents with left hemispheric TIA symptoms at increasing frequency. Carotid Doppler US and CTA neck show severe stenosis of left ICA with non-circumferential calcification of plaque at the carotid bifurcation. Patient's medical comorbidities preclude carotid endarterectomy.
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CTA of carotid stenosis
CTA reformat is used for planning of carotid angioplasty and stenting (CAS).
70 year old male presents with left hemispheric TIA symptoms at increasing frequency. Carotid Doppler US and CTA neck show severe stenosis of left ICA with non-circumferential calcification of plaque at carotid bifurcation. Patient's medical comorbidities preclude carotid endarterectomy.
Principles of device selection based on lesion size, vessel diameter, and available example device choices. Use CTA reformat to measure:
1) ICA diameter (far distal) = 4 mm. Choose Cordis AngioGuard basket diameter 5 mm, which covers vessel diameter range 3.5 - 4.5 mm.
2) ICA diameter proximal to plaque = 7 mm, distal to plaque = 5 mm. Plaque length = 15 mm. Accounting for entrance (5 mm) and exit (5 mm) from the lesion = 25 mm. Choose Protege diameter 8 mm taper to 6 mm x 30 mm length (with conical tip).
3) Predilation balloon: Monorail Maverick2 diameter = 3 mm (at 6 atm pressure), 3.37 mm (at 14 atm max rated pressure) x 30 mm balloon length (to cover the entire stent length). Make sure the device is ~ 140 cm long.
4) Post stenting balloon (diameter < ICA diameter distal to plaque): Monorail Sterling 5 mm (at 6 atm) 5.47 mm (at 14 atm) x 20 mm balloon length (shorter just to cover the stenosis). Make sure the device is ~135 cm long.
5) Catheter access plan: CTA determines approximate level of bifurcation and pre-planned parking location of Start with 5F Bern (vessel selection, CCA and parking into ECA). Exchange with 6F Shuttle using Amplatz Extra Stiff (260 cm). Then use Cordis Angioguard to establish distal emboli capture and monorail guidewire, which facilitate subsequent angioplasty and stenting.
Additional points to remember:
1) Patient should have been pre-treated with ECASA, Plavix.
2) During procedure Heparinize when in abdominal aorta to ACT of 300 by anesthetist.
3) Pre-dilation use glycopruide + Atropine to pretreat to avoid bradycardia.
4) Pre-dilation carries significant embolization risk. Post-dilation can also dislodge emboli herniated through the stent struts.
5) Basket retrieval should be timed with vessel pulsation to avoid tugging the distal edge of the deployed stent.
6) Post treatment, the patient should have at least 6 months of antiplatelet treatment, e.g., Plavix (Canadian code 376) + ASA. Note BP variations post procedure, will need to organize GP follow up for BP medication adjustments.
7) Order post procedure baseline Carotid Doppler for future follow up.