Carotid Stenting of Multichannel Pseudoocclusion of Internal Carotid Artery using 5-French Picard as a Supporting Catheter for Microwire Navigation Across Tight Stenosis: Report of Two Cases

Sir, Multichannel pseudoocclusion of internal carotid artery (ICA) is a severe stenosis with multiple vascular channels and distal adaptive collapse.[1] It is presumed to occur in previously occluded carotid bulb reconstituted by small vascular channels.[2] Carotid artery stenting (CAS) in these pseudo occlusions is always difficult due to the tight stenosis and multiple tortuous vascular channels. We describe two cases of multichannel pseudoocclusion of ICA in which probing of microguidewire through the tight stenosis was done using the triaxial system of microguidewire, microcatheter, and 5-French Picard catheter to provide support to the microwire navigation across the tight stenosis. A 65-year-old male presented in emergency with gradually increasing right-sided motor weakness for 2 days. He also had an episode of transient speech difficulty which recovered completely. Magnetic resonance imaging of the brain showed acute small infarct in the posterior limb of the left internal capsule [Figure 1a]. Magnetic resonance angiography showed the tight stenosis of the left carotid bulb with faint flow-related enhancement of the cervical segment of the left ICA. No flow-related enhancement noted in the intracranial segment of ICA likely due to very slow anterograde flow. Left ICA territory was perfusing via the anterior communicating artery. He had a history of type-2 diabetes mellitus and hypertension. He also had a history of coronary angioplasty. Two-dimensional echocardiography showed the left ventricular ejection fraction of 35% with mild tricuspid regurgitation and trace aortic regurgitation. The patient was regularly taking aspirin 150 mg. Informed consent from the patient for carotid stenting was obtained. He was loaded with oral dual antiplatelet therapy (aspirin 150 mg and clopidogrel 450 mg) one day prior to the procedure followed by dual antiplatelet therapy (aspirin 150 mg and clopidogrel 150 mg) 3 h before the procedure on the day of the procedure. Left CAS was performed through transfemoral route under local anesthesia. Systemic anticoagulation was started immediately after the insertion of short femoral 8-F sheath with a bolus of 5000 IU of heparin to attain an activated clotting time of more than 300. After placing a short 8-F sheath in the femoral artery, 6-F Shuttle sheath (Cook, Bloomington, Indiana) was placed in the left common carotid artery (CCA). Left CCA injection showed multichannel pseudoocclusion of the carotid bulb with slow antegrade flow distally in the ICA [Figure 1b]. Traxcess 14 microguidewire (Microvention, Columbia Aliso Viejo, USA.) was advanced through the echelon microcatheter (ev3, Irvine, California, USA) into the carotid bulb. While trying to navigate the microguidewire across the stenosis, the microcatheter and microwire coaxial system was continuously flopping into the external carotid artery [Figure 1c]. We used triaxial system with 5-F Picard catheter (Cook, USA), Echleon microcatheter, and microguidewire to provide good support, and thus, allowing the probing of the microwire through the tight stenosis and tortuous vascular channels. With the help of a good back-up support of Picard catheter, microguidewire was then smoothly navigated across one of the channels followed by microcatheter [Figure 1d]. After the microcatheter and microguidewire were parked across the stenosis, traxcess docking wire was docked to the microguidewire and with the help of exchange maneuver, Spider FXTM (ev3, MN, USA) filter was parked in distal cervical ICA. Prestent angioplasty was done with 3 × 25 mm balloon [Figure 1e]. The Xact stent (Abbott Vascular, Redwood City, California) was then placed across the stenosis and followed poststent angioplasty with 4 × 20 mm balloon [Figure 1f]. Final check angiogram of CCA showed well-opened stent [Figure 1f]. Distal protection device was retrieved. Left CCA angiogram showed normal opacification of ICA with a stent in situ with normal anterograde flow into the ICA territory [Figure 1g]. Control angiograms were done for 30 min to observe the patency of stent and clot formation. The patient was discharged after 5 days with modified Rankin scale (mRS) of 2. Two antiplatelet agents were continued for 6 months after surgery, after which one of the agents was discontinued. Clinical follow-up was done at 3 and 6 months and the patient was functional and independent without the recurrence of symptom. Our institutional protocol is to perform computed tomography angiography (CTA) after 6 months; however, the patient refused for the CTA investigation. Doppler study screening was done at 6 months, which showed well-opened stent.Figure 1: Diffusion-weighted imaging shows acute infarct in left internal capsule (a). Left CCA injection shows multichannel pseudoocclusion of left carotid bulb with slow anterograde flow (b). Road map shows difficulty in navigating the wire across the stenosis and no support for the microcatheter in carotid bulb (c). Echleon microcatheter was advanced across the tight stenosis with the support of Picard catheter (arrow) (d). Spider FX device in distal ICA (e). Stent deployment across the stenosis (f). Normal anterograde flow into ICA territory (g)A 75-year-old male with recurrent transient ischemic attacks for 2 days presented with left-sided weakness and numbness of left upper and lower limb which recovered completely. He also had a history of right middle cerebral artery territory stroke 3 months ago. He was known for hypertensive and on irregular treatment. He had a history of coronary angioplasty. There was chronic focal infarct in the right precentral gyrus on noncontrast computed tomography head [Figure 2a]. CTA was performed at that time, which showed the tight stenosis of the right carotid bulb and normal intracranial vessels [Figure 2b and c]. CAS was planned after the informed consent was received from the patient. Dual antiplatelet therapy was administered as a loading dose a day prior to and at the day of the procedure. Right CAS was performed through transfemoral route under local anesthesia. After placing a short 8-F sheath in the femoral artery, 6-F Shuttle sheath was placed in the right CCA. Right CCA injection showed multichannel pseudoocclusion with the distal collapse of ICA with slow anterograde flow [Figure 2d and e]. Microguidewire and microcatheter were smoothly navigated through one of the tortuous channels with the help of Picard catheter [Figure 2f]. With the help of exchange maneuver, balloon angioplasty was first done before placing the Spider FXTM filter [Figure 2g]. This was followed by placement of filter and then deployment of a stent. Poststent angioplasty was done with 4 ×20 mm balloon. Right CCA injection showed well-opened stent and good antegrade flow into the intracranial ICA, MCA, and ACA [Figure 2h and i]. There was no procedural-related complication. Follow-up CTA was done after 6 months, which showed normal opacification of ICA with the stent in situ [Figure 2j and k]. No in-stent stenosis was noted.Figure 2: Noncontrast computed tomography head shows chronic focal infarct in the right motor cortex (a). CTA shows the tight stenosis of the right carotid bulb and normal intracranial vessels (b and c). Right CCA injection shows multichannel pseudocclusion of the right carotid bulb and slow anterograde flow (d and e). Echleon microcatheter was advanced across the tight stenosis with the support of Picard catheter (f). Spider FX device in distal ICA and the stent was deployed across the stenosis (g and h). Good anterograde flow seen into ICA territory (i). CTA after 6 months shows no instent thrombosis and stenosis (j and k)The risk of stroke in patients with ICA pseudoocclusion is 11–18% after the medical management alone according to the North American Symptomatic Carotid Endarterectomy Trial subtype analysis.[3] Treatment of multichannel pseudoocclusion is controversial. The efficacy of surgery and CAS in treating multichannel pseudoocclusion to prevent stroke has been reported by some studies.[3-6] Hirata et al.[7] classified patients with pseudoocclusions into two groups: (1) those with severe stenosis of the original lumen and (2) those with a thrombotic total occlusion and lumen recanalization by large neovascular channels. The later group classified by Hirata corresponds to our two cases with multichannel pseudoocclusion. Matsuda et al.[6] discussed the angiographic characteristics of pseudo-occlusion of the ICA before and after CAS. In their study, adverse events were more frequent in the multiple-channel group than in the single-channel group. There were higher chances of in-stent occlusion in multichannel group compared to single-channel group. Our cases had a favourable outcome and stent patency on follow-up imaging after 6 months. Matsuda et al.[6] also reported restricted dilatation of distal ICA after stenting was more common in the multichannel group in their study and speculated that the intimal cell proliferation in distal ICA had undergone some organic changes, which kept the distal ICA narrowed immediately after the CAS. In our cases, distal ICA was dilated immediately after the stenting and there was no in-stent stenosis and ICA collapse at 6-month follow-up imaging. Carotid stenting can be safely done in multichannel pseudoocclusion of the carotid artery by smoothly negotiating the microguidewire beyond the tight stenosis with the help of microcatheter and 5-French Picard catheter support. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.