Mechanical Thrombectomy for Acute Common Carotid Artery Occlusion

Abstract

Mechanical thrombectomy (MT) is the standard treatment for acute large occlusion of the cerebral artery. Evidence for the success of this procedure was based on the treatment of patients with internal carotid artery and middle cerebral artery thrombi. There are a few reports on thrombi extending to the common carotid artery (CCA). We document our endovascular procedure and the clinical outcome in seven consecutive patients who underwent MT for CCA thrombi between September 2016 and April 2021. Their mean National Institutes of Health Stroke Scale score was 20.0 (range, 9-30), and the mean diffusion-weighted imaging Alberta Stroke Program Early Computed Tomography Score on magnetic resonance images was 8.7 (range, 7-10). In six patients, MT of the CCA occlusion was successful, and the mean puncture-to-reperfusion time was 84 minutes (range, 39-211 minutes). In five patients, successful reperfusion was obtained. The mean total pass number was 4.1 (range, 2-7). Due to large thrombi, we performed balloon guide catheter (BGC) occlusion in three patients. Sheath occlusion occurred in two, and thrombus migration into the femoral artery around the sheath was observed in two patients. The mean modified Rankin Scale score 3 months post-stroke was 3.6 (range, 2-5). When the removal of a large CCA thrombus is attempted in a single step, catheter and sheath occlusion may occur, and this increases the risk for critical systemic artery occlusion. Therefore, we suggest that MT be combined with the BGC technique and propose the use of a large aspiration catheter to decrease the volume of the thrombus.

Introduction

Mechanical thrombectomy (MT) is the standard treatment in patients with acute stroke due to main-trunk cerebral artery occlusion.^1-4) Immediate endovascular treatment is required because speedy revascularization leads to better outcomes.^1-3,5,6)

According to Romoli et al.,⁷⁾ the onset-to-needle time was associated with a good functional prognosis, and the longer the time, the worse the outcome. Also, the number of passes required for recanalization was suggested to affect clinical outcomes.^8-10) The effectiveness of the first pass for revascularization was associated with a better neurological prognosis.^10-14) First-pass success tends to result in a shorter clot length, a shorter distance from the internal carotid artery (ICA) terminus, and a larger angle of interaction.¹⁵⁾

In only 33%-50% of patients with thrombi in the ICA or the M1 portion of the middle cerebral artery (MCA) was the first pass successful, irrespective of the applied thrombectomy technique, e.g., aspiration, stent retrieval, or a combination of techniques.¹²⁾

Thrombi extending into the common carotid artery (CCA) territory are rare.^16-18) In patients with CCA occlusion, successful recanalization by the usual MT method may be difficult because the vessel is wide and the thrombus can be large. We report our endovascular procedure and the clinical outcome in seven patients whose CCA occlusions were addressed by MT.

Materials and Methods

Our study was approved by the institutional ethics committee of our hospital (approval number 892). Prior informed consent for the procedure was obtained from all patients, and written informed consent for inclusion in this study was waived because it is retrospective and patients could opt out on our institutions' home pages.

Patients

Between September 2016 and April 2021, seven consecutive patients (three females and four males, average age of 78.1 years, ranging from 69 to 87 years) with acute CCA occlusion, four on the right side and three on the left side, underwent MT. The pretreatment modified Rankin Scale (mRS) score was 0 in five patients, 2 in one patient with an earlier cerebral infarct, and 3 in another with chronic heart failure.

All patients met the criteria for age (age ≧18 years), groin puncture within 6 hours after stroke onset, a diffusion-weighted imaging Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS) of ≧6 on brain DWI magnetic resonance images (MRI), a National Institutes of Health Stroke Scale (NIHSS) score of ≧6, and CCA thrombus progression confirmed on digital subtraction angiography.

Pre-procedure data included the DWI-ASPECTS at the time of admission and the CCA diameter at the occlusion site calculated by comparing it with the outer diameter of the balloon guide catheter (BGC). The treatment characteristics were the minutes from puncture to reperfusion, intravenous alteplase treatment, direct aspiration with a BGC, the number of passes required for reperfusion, femoral sheath obstruction during the procedure, and recanalization improvement determined with the thrombolysis in cerebral infarction (TICI) grade.^19,20) The post-procedure imaging characteristics were carotid artery stenosis after MT and intracranial hemorrhage. The clinical outcomes were evaluated based on the mRS score obtained 3 months after surgery and a diagnosis of symptomatic hemorrhage as defined by the criteria promulgated by the European Cooperative Acute Stroke Study-2 (ECASS-2).²¹⁾

Endovascular procedure

All procedures were performed under local anesthesia. An 8- or 9-Fr sheath was placed in the right femoral artery and an 8- or 9-Fr BGC (usually Optimo, Tokai Medical Products, Aichi, Japan) was pushed to the CCA using a coaxial catheter. MT was performed with a stent retriever, a large-bore aspiration catheter, or a BGC.

For aspiration with the BGC, the catheter was advanced to the face of the thrombus, the balloon was inflated, and manual aspiration via the BGC was performed. When no blood and clot discharge was observed, the BGC was removed, and manual aspiration was continued. This step was akin to a direct aspiration first-pass technique (ADAPT) performed after deflation of the balloon.²²⁾ Before inserting the stent retriever, we confirmed access of the intravascular microcatheter across the thrombus. Then the stent retriever, deployed across the thrombus, was pushed out of the microcatheter into the thrombus and then withdrawn into the inflated BGC under continuous aspiration.

In the combination technique, the BGC was inflated, and a large-bore aspiration catheter was navigated into the patent segment of the artery to the face of the thrombus. Then a stent retriever (Trevo, Stryker, Kalamazoo, MI, USA) or a Solitaire stent (Medtronic, Irvine, CA, USA) was placed across the thrombus via the aspiration catheter, and an activated aspiration catheter pump was applied. The stent retriever was then completely deployed, and the microcatheter was removed to increase the aspiration force. The aspiration catheter (Penumbra, Penumbra Inc., Alameda, CA, USA, or a Catalyst catheter, Stryker) was advanced over the stent retriever wire until the drip rate of the aspiration catheter pump decreased. Lastly, under continuous aspiration, the aspiration catheter, clot, and stent retriever were withdrawn from the inflated BGC. This technique involved continuous aspiration prior to intracranial vascular embolectomy (CAPTIVE) technique²³⁾ and an inflated BGC.

Our study is a retrospective study that involved three participating institutes. There was no fixed protocol, and the treatment procedure was selected at the discretion of the attending surgeon. In a patient with severe ICA stenosis, we considered percutaneous transluminal angioplasty (PTA) at the distal ICA thrombus and carotid artery stenting (CAS) if necessary.

Results

Preprocedure patient characteristics

As shown in Table 1, at the time of hospital admission, the mean NIHSS score of our seven patients was 20.0 (range, 9-30), and the mean DWI-ASPECTS on MRI scans was 8.7 (range, 7-10). Before intervention, patients 1, 2, and 3 were treated with a recombinant tissue plasminogen activator (rt-PA). The mean CCA diameter on angiograms was 8.2 mm (range, 7.3-9.6 mm).

Table 1.

Patient characteristics

Patient	Age (years)	Sex	Prestroke mRS	Site	Admission NIHSS	Admission DWI-ASPECTS	Pretreatment rt-PA	CCA diameter (mm)
1	71	M	0	lt	27	10	+	9.3
2	69	M	0	lt	22	7	+	7.5
3	82	F	0	rt	10	10	+	8.1
4	82	F	2	lt	22	9	-	7.8
5	82	M	0	rt	9	9	-	7.5
6	74	M	0	rt	20	9	-	7.3
7	87	F	3	rt	30	7	-	9.6

CCA, common carotid artery; DWI-ASPECTS, Diffusion-Weighted Imaging Alberta Stroke Program Early Computed Tomography Score; F, female; M, male; lt, left; rt, right; mRS, modified Rankin Scale; NIHSS, National Institutes of Health Stroke Scale; rt-PA, recombinant tissue plasminogen activator

Mechanical thrombectomy

MT was performed at the discretion of the attending surgeon (Table 2). In patients 2 and 5, application of the ADAPT, followed by BGC aspiration, was useful. However, in patient 2, a 69-year-old male who presented with a tandem lesion, we observed embolization of the distal anterior and middle cerebral arteries. His proximal MCA occlusions were first addressed with ADAPT but then abandoned because of iatrogenic ICA dissection.

Table 2.

Mechanical thrombectomy procedures, complications, and outcome

Patient	Mechanical thrombectomy	Sheath occlusion	Suspect of thrombus movement into the FA	Puncture to recanalization	Number of passes	TICI grade	NIHSS post-stroke		mRS 3 months post-stroke
				time (min)			POD 1	POD 14
1	A/BGC - A/AC - Rem/BGC	+	-	41	2	3	4	3	2
2	A/BGC x2 (A/AC for M1 occlusion due to EDT)	-	-	39	3	2a	28	22	4
3	A/AC - A/BGC - Stent - A/AC x2	-	-	No pass	5	1	28	24	4
4	A/BGC - A/AC x3 - Comb - Rem/BGC (Comb for M2 occlusion due to EDT)	-	+	109	6	3	9	9	4
5	A/AC x6 - A/BGC	-	+	211	7	2b	24	24	5
6	A/BGC - A/AC	-	-	39	2	2b	2	2	2
	*EDT of distal MCA was observed
7	A/BGC - A/AC- Rem/BGC - A/AC- Comb - Rem/BGC	+	-	65	4	3	15	9	4

A/AC, aspiration by aspiration catheter; A/BGC, aspiration with balloon guide catheter; Comb, combined technique with stent and aspiration; mRS, modified Rankin Scale; EDT, embolization to distal territory; MCA, middle cerebral artery; POD, postoperative day; Rem/BGC, removal of balloon guide catheter; Stent, stent retriever; TICI, thrombolysis in cerebral infarction

In patients 1, 4, 6, and 7, BGC aspiration failed and subsequent ADAPT was required. The BGC became occluded and was withdrawn in patients 1, 4, and 7; additional sheath occlusion occurred in patients 1 and 7. Embolization of the distal MCA territory was observed in patients 4 and 6. It was addressed successfully in patient 4 by applying our combination technique for occlusion of the M2 portion of the MCA. We unsuccessfully attempted five passes in patient 3.

The ICA was severely stenotic in patient 5. This patient harbored thrombus distal to the ICA stenosis. To retrieve the distal ICA thrombus, we considered PTA and CAS for the severe ICA stenosis. However, the additional therapy was abandoned because of delayed recanalization time (211 minutes).

Occlusion of the sheath and/or the BGC

When BGC occlusion occurs without sheath occlusion, successful forced manual suction from the side port of the sheath can be confirmed by a backflow of blood, and the BGC together with the sheath can be removed safely. During MT, we encountered sheath and BGC occlusion in patients 1 and 7. Therefore, we first applied manual suction from the side port of the sheath and confirmed that a part of the thrombus had moved into the clear portion of the side port. We subsequently obtained an angiogram of the abdominal aorta; it was acquired from the contralateral sheath on the femoral artery. After ascertaining the absence of a massive thrombus attached to the occluded sheath tip, we cut the sheath at a site near the side port. When we observed outflow of the clot and blood, we removed the recanalized sheath completely (Fig. 1).

Fig. 1.

Our method of dealing with sheath/BGC occlusion in patient 7.

A. The proximal side of the sheath was occluded with a Pean clamp and cut with scissors at a site just distal to its end because blood clots tend to get stuck in the narrow lumen of the sheath part that transitions to the extension tube of the side port.

B. Blood flow is seen upon reopening the sheath.

C. The thrombus is seen from the end of the cut sheath by pushing the blood clot out of the side port.

D. The thrombus is retrieved from the occluded sheath and catheter.

Overall results

With the exception of patient 3, MT addressing CCA occlusion was successful. The mean interval from puncture to reperfusion was 84 minutes (range, 39-211 minutes); a mean of 4.1 passes (range, 2-7) was required. In patients 1, 4, and 6, reperfusion was obtained. Their TICI scale was 2b or 3. None of our patients developed posttreatment symptomatic intracranial hemorrhage. Pre-stroke ICA stenosis was encountered in patient 4; in patient 5, it was suspected. Three months post-stroke, the mean mRS score of our seven patients was 3.6 (range, 2-5).

Discussion

In our study, MT was successful in six of our seven patients harboring a CCA thrombus; successful reperfusion was obtained in five of the seven, and their TICI grade was 2b or 3. Blood clot evacuation required a mean of 4.1 passes. In patients with large CCA thrombi, we encountered sheath and/or BGC occlusion. In all patients, the thrombus extended to the cervical ICA, and the collateral flow from the contralateral ICA via the superior thyroid artery and the collaterals from the vertebral artery via the occipital muscle branch, was insufficient. In addition, the large thrombi leading to CCA occlusion rendered recanalization difficult and resulted in a poor prognosis.

The outcome of the endovascular treatment for CCA occlusion was not satisfactory. These results might be attributed to several factors. Patients 4 and 7 presented with high mRS score prior to the onset of symptoms (2 and 3, respectively). In patient 5, the interval between puncture and recanalization was prolonged (211 min). In patient 3, the MT procedure failed. Lastly, in patient 2, ADAPT was abandoned because of iatrogenic ICA dissection. Although patients 2, 4, and 6 presented with embolization to the distal territory of the CCA, this had no significant impact on their prognosis.

Others^24-26) reported that the time to revascularization was longer in patients with ICA and CCA occlusion than in patients with no CCA occlusion and that successful MT is more difficult to achieve in patients with a CCA than an ICA thrombus.^8,24,25,27) We suspect that the hardness and size of the thrombus and our attempts of evacuation via various techniques prolonged the time to revascularization (Table 3). Effective procedures to address CCA occlusion are needed to shorten the time to revascularization.

Table 3.

Comparison of our result with previous reports

Case series of mechanical thrombectomy		Our result	ICA and CCA occlusion cases (22)	Multicenter international retrospective study for ICA or MCA occlusion (24)
				Direct aspiration	Stent retriever
Number of cases		7	153	107	121
Patient characteristics	Age	mean 82.0	median 71	mean 69.8	mean 68.9
	NIHSS on admission (mean)	22 (15–24.5)	19 (7)	16.4 ± 6.9	15.7 ± 6.7
Occlusion site (number)	CCA occlusion	7	4	-	-
	ICA occlusion	0	149	30	33
Procedure characteristics	Time to recanalization (min)	mean 84
		median 65	median 71	mean 28.2	mean 43.8
	total pass; mean ± SD	4.1 ± 2.0	-	1.9 ± 1.9	1.7 ± 1.0
Outcome	TICI2b-3 (%)	71	88	91	88
	mRS score ≦2	29%	27%	-	-
	mRS (mean ± SD)	3.6 ± 1.1	-	3.0 ± 2.4	3.0 ± 2.4

CCA, common carotid artery; ICA, internal carotid artery; MCA, middle cerebral artery; mRS, modified Rankin Scale 3 months after the procedure; NIHSS, National Institutes of Health Stroke Scale

Staessens et al.²⁸⁾ suggest that fibrin-rich thrombi may hamper the effectiveness of MT as they may be resistant to retrieval and may require several recanalization passes. CCA thrombi tend to be hard; however, the collapse of large but soft CCA thrombi may result in their moving to the periphery of the vessel. According to Baek et al.,²⁹⁾ the thrombus volume was significantly related with successful recanalization with a stent retriever; the larger the volume, the more passes were required for recanalization. On pre-procedural angiograms, the mean CCA diameter in our seven patients was 8.2 mm; however, the diameter of available stents was 6 mm. As the CCA thrombi in patients 2 and 6 were aspirated with the aid of a BGC or an aspiration catheter, and neither catheter occlusion nor sheath occlusion was encountered, we suspect that their thrombi were not very hard and not very large. We had difficulty evacuating the thrombi of patients 1, 3, 4, 5, and 7. Sheath and/or catheter occlusion in patients 1, 4, and 7 suggests that their thrombi were large and hard. The size and hardness of the clot may play a role in the success or failure of MT. Eesa et al.³⁰⁾ reported that in some patients, a portion of the ICA occlusion responded to BGC aspiration of the clot. Asano et al.²⁵⁾ found BGC aspiration to be effective for CCA occlusion. This procedure was successful in patient 2 but required two aspiration attempts. BGC aspiration can be difficult when the CCA thrombus is large; the catheter became occluded in patients 1, 4, and 7 and the sheath in patients 1 and 7.

Sheath occlusion was attributable to the presence of a large amount of the clot in the BGC, and its removal, catheter cleaning, and reinsertion were time-consuming. Because the clot may be hard and/or large, and the guiding catheter or sheath introducer may unexpectedly become occluded, this eventuality must be taken into account in patients with CCA occlusion. Therefore, to reduce the thrombus volume occluding the CCA, we suggest that a large-diameter aspiration catheter be used.

Although the removal of an ICA-occluding thrombus should be performed in as few attempts as possible,^9,10,31) efforts to retrieve a large thrombus in a single aspiration step may elicit systemic critical events because when the clot fails to pass through the BGC, vessels supplying other organs or limbs may become embolized. Pieces of CCA-occluding clots may adhere to the catheters, and attempts at in toto removal may be risky. The repeated aspiration of clot pieces using a larger aspiration device may be relatively safe. When clot pieces enter the BGC, their removal is not difficult. Intra-procedurally, the balloon should be expanded enough to interrupt anterograde blood flow in the CCA. The thrombus can then be evacuated by repeat aspirations using an aspiration device. If these aspiration efforts fail to remove a sufficient clot amount, the thrombus may be unexpectedly hard, and the application of a combination technique using a stent or double-stent technique may be required.^18,29,31)

In the presence of sheath occlusion, we recommend placing another sheath in the contralateral femoral artery and thereafter acquiring an angiogram to ascertain the absence of a thrombus around the first sheath. When a clot is observed, thrombectomy in that sheath or direct removal of the thrombus may be required to prevent critical femoral artery occlusion. When the sheath was narrow around the side port and occluded at that site, we used scissors to cut the sheath close to the side port, thereby releasing the occlusion. Thereafter, the thrombus, along with pieces located around the tip of the sheath, flowed out and femoral artery occlusion was avoided.

Bhambri et al.³²⁾ presented a meta-analysis and systematic review of thrombus histology as it relates to MT. They found that a hyperdense artery sign on brain CT scans was associated with a higher red blood cell count in the clot and that fibrin-/platelet-rich clots were associated with longer procedure times. Their findings suggest that imaging findings may help to predict recanalization. We did not examine CCA clot hardness radiologically or pathologically although we think that pre-procedure knowledge of the clot hardness in patients with CCA occlusion is needed to evaluate the chance of successful recanalization.

Study limitations

Our study was retrospective and the number of patients was small. The treatment strategy was devised by the individual surgeon and not uniform. Consequently, the validity of our findings must be verified by studies of more patients subjected to our methods.

Conclusions

In six of our seven patients, MT was successful and reperfusion was obtained. We were able to resolve several instances of sheath and/or BGC occlusion. Attempts to evacuate large thrombi in one step increases the risk for catheter and sheath occlusion and may result in critical systemic artery occlusion. Therefore, we recommend the combination of MT and another technique after the removal of as much as possible of massive and/or hard CCA thrombi with a large aspiration catheter.

Conflicts of Interest Disclosure

The authors declare they have no conflicts of interest and no commercial relationships and received no support from pharmaceutical or other companies. All authors are members of the Japan Neurosurgical Society (JNS) and have completed the Self-reported COI Disclosure Statement Forms available at the website for JNS members.