Stent Retriever (Stentriever) Thrombectomy for Acute Ischemic Stroke

Fig. 11.1

Illustrations of coaxial technique for placing balloon guiding catheter. (a) Bovine-type left common carotid artery origin. (b) The origin of the left common carotid artery is catheterized using a 5 F angiocatheter, and the left external carotid artery is navigated using a 0.035-inch wire. (c) The 5 F angiocatheter is advanced over the 0.035-inch wire to the external carotid artery. (d) The balloon guiding catheter is advanced over the 5 F catheter and 0.035-inch wire. If needed, the 0.035-inch wire is replaced with a stiff 0.035-inch wire before advancing the balloon guiding catheter

11.1.2 Microcatheter Navigation and Stentriever Deployment

A 4-mm diameter stentriever is compatible with a microcatheter with a 0.0195-inch inner diameter. Thus, any type of microcatheter (Excelsior 1018, Rebar-18, or Prowler Plus) with a ≥0.0195-inch inner diameter can be used according to personal preference. However, when using a 5-mm or 6-mm diameter stentriever, a microcatheter with a 0.027-inch inner diameter is required. The microcatheter is navigated beyond the occluded point of the relevant intracranial artery using a 0.014-inch microwire. Thereafter, a small amount of contrast material is infused to confirm that the microcatheter has been correctly positioned in the main branch of the occluded parent artery. An appropriate-sized stentriever is then introduced and deployed to span the entire length of the occluded clot. After positioning the distal tip marker of the stentriever, instead of unsheathing the microcatheter, the stentriever is deployed by pushing the stentriever delivery wire, the so-called “push and fluff” technique (Fig. 11.2). This technique leads to a better wall apposition of the stentriever and cell size/configuration, which in turn promotes better engagement of the clot with the stentriever and increases the chance of first-pass recanalization [16]. A control angiogram is generally obtained immediately after deploying the stentriever to confirm the accuracy of the stentriever position and restoration of the blood flow beyond the initial occlusion site.

Fig. 11.2

Ideal technique of stentriever deployment. (a) Illustration of predominant unsheathing of the microcatheter: this can leave a gap between the stent and the vessel wall at the curvature. Note the cell configuration is elongated. (b) “Push and pull” for unsheathing the distal segment of the stentriever, plus “push and fluff” technique for deployment of the remaining segment of the stentriever. This facilitates better apposition of the stentriever to the vessel wall at the curvature. Note more fluffing of the cell configuration, which promotes thrombus engagement with the stentriever

11.1.3 Retrieval of Stentriever

An additional control angiogram is obtained after waiting 3–5 min and inflating the BGC balloon, which appears as cylindrical. During the simultaneous retrieval of the stentriever and the microcatheter, the BGC needs to be continuously suctioned to prevent any distal embolization. Plus, after retrieving the stentriever, the BGC still needs to be continuously suctioned until clear blood without any clot debris is aspirated. Finally, the BGC is deflated and a control angiogram is obtained. Figure 10.3 shows the steps of a stentriever thrombectomy after placing the BGC (Fig. 11.3a–j).

Fig. 11.3

Basic steps of stentriever thrombectomy after balloon guiding catheter placement. (a) The left middle cerebral artery occluded with a large amount of clots is navigated blindly using a microcatheter and wire. The arrow indicates the microcatheter tip marker. (b) Illustration of Fig. 11.3a. (c) Deployment of the stentriever. The microcatheter tip is located within the clots. The distal markers of the stentriever are placed at the inferior branch of the left middle cerebral artery. (d) Illustration of Fig. 11.3c. (e) Fully deployed stentriever. (f) Illustration of Fig 11.3e. (g) After waiting 3–5 min, the balloon guiding catheter is inflated to arrest the blood flow, and the stentriever and microcatheter are then simultaneously retrieved. The balloon guiding catheter needs to be continuously suctioned during and immediately after the retrieval until clear blood without any clot debris is aspirated. (h) Illustration of Fig. 11.3g. The line arrows and dotted arrows indicate the tip marker of the microcatheter and distal markers of the stentriever. (i, j) After the aspiration of clear blood without any clot debris from the balloon guiding catheter, the balloon is deflated and a control angiogram obtained. Frontal (i) and lateral (j) angiograms showing complete recanalization

11.2 Complex Situations

11.2.1 Very Tortuous Cervical and Cavernous Segment

If the relevant parent artery is very tortuous or includes a stenotic segment proximal to the occlusion site, the probability of losing the stentriever-engaged clots increases, plus continuous suction of the BGC may not be effective to prevent distal embolization. In this case, the coaxial use of a 4 or 5 F intermediate (Envoy DA, Navien, Revive, and Neuron, etc.) or aspiration catheter (Penumbra) can help to increase the chance of complete clot retrieval. An aspiration catheter (Penumbra, Alameda, CA) or an intermediate catheter (Navien, Revive, Neuron, etc.) is coaxially introduced through the BGC and advanced as close as possible to the stentriever-engaged clots (Fig. 11.4). This helps to prevent the loss of engaged clots when pulling the stentriever back through the tortuous (Fig. 11.5) or stenotic segment (Fig. 11.6) of the parent artery. It also facilitates the sequential or simultaneous performance of a stentriever thrombectomy and aspiration thrombectomy (Figs. 11.5 and 11.6).

Fig. 11.4

Simultaneous utilization of aspiration and stentriever thrombectomies. (a) Illustration of simultaneous utilization of stentriever thrombectomy and suction thrombectomy. (b) Angiogram immediately after stentriever deployment (line arrow). This patient has a tortuous cervical internal carotid artery and left terminal internal carotid artery occlusion. (c) After three failed passes of the stentriever via a balloon guiding catheter, a 5 F intermediate catheter (dotted arrow) is advanced over the microcatheter, then a stentriever is deployed for suction, and a stentriever thrombectomy is performed simultaneously

Fig. 11.5

A 77-year-old woman presenting with initial NIHSS score of 18. (a) Left carotid angiogram revealing occlusion of the left cervical internal carotid artery. (b) A suction thrombectomy is conducted using a balloon guiding catheter (arrow). (c) Angiogram taken immediately after the suction thrombectomy revealing a tandem occlusion of the left middle cerebral artery. Note that the cervical segment of the internal carotid artery is tortuous. (d) A microcatheter (arrow) is navigated under roadmap image. (e) Angiogram immediately after the stentriever deployment revealing a clot at the left middle cerebral artery bifurcation. (f) Repeated failure of a stentriever thrombectomy. (g) A Penumbra is advanced to meet the occluding clot via a roadmap. (h) Complete recanalization is achieved after an aspiration thrombectomy using the Penumbra

Fig. 11.6

A 69-year-old man presenting with mental change. (a) Right vertebral angiogram showing occlusion of the left vertebral artery V4 portion. The left vertebral artery is occluded (not shown). (b) Angiogram after navigation of a microcatheter into the basilar artery revealing tandem occlusion of the vertebral artery and basilar artery (dotted arrow). Note thrombi (arrowheads) proximal to a focal stenosis (arrow). (c) After simultaneous application of a suction thrombectomy using a 5 F intermediate catheter (arrow) and a stentriever thrombectomy, angiogram revealing remnant occlusion of the basilar artery with floating clots (dotted arrow). (d) Unsubtracted angiogram following stentriever deployment from the basilar artery to the left posterior cerebral artery (white arrow). (e) Lateral angiogram immediately after stentriever deployment showing clots (arrowhead) jailed by the stentriever along the posterior wall of the basilar artery. (f, g) The intermediate catheter (dotted arrow) is advanced to bypass the stenotic segment of the vertebral artery, followed by stentriever retrieval (arrow). (h) Immediately following simultaneous suction and a stentriever thrombectomy, angiogram revealing recanalization of the basilar artery, yet remnant occlusion of the right superior cerebellar artery (arrow). (i) The stentriever is deployed in the superior cerebral artery via a roadmap. (j) Angiogram after one pass of the stentriever showing complete recanalization. (k) 10-min delay angiogram showing recoiling of the stenosis (arrow) of the vertebral artery toward reocclusion. (l) Following intra-arterial administration of glycoprotein IIb/IIIa inhibitor, the stenosis (arrow) is improved. (m) MR angiogram on the next day showing a focal severe degree of stenosis of the right vertebral artery and occlusion of the left vertebral artery

11.2.2 A Large Amount of Clots in the Cervical and/or Cavernous Segment

In the case of a large amount of clots in the cervical artery concomitant with a tandem intracranial artery occlusion, it is actually impossible to remove all the clots using just a stentriever. In this situation, it is more effective to perform a suction thrombectomy first using a BGC and/or large bore shuttle sheath before the stentriever thrombectomy. Plus, since the BGC can be occluded by packed clots during the suction thrombectomy, a coaxial combination of an 8 F BGC within an 8 F shuttle sheath is also needed, which, in the case of occlusion, allows the BGC to be deflated and retrieved outside the shuttle sheath, while maintaining the negative suction of the BGC. Thereafter, the shuttle sheath left in the cervical artery needs continuous suctioning until clear blood is aspirated (Fig. 11.7). Following the suction thrombectomy, a stentriever thrombectomy can be performed to remove any remnant distal clots (Figs. 11.5 and 11.7).