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Abstract
Background Our initial experience using the two-stage aspiration technique (TSAT) with proximal flow arrest by a balloon guiding catheter is presented. In TSAT, aspiration is applied with the 5MAX ACE and also with the 3MAX catheter with a Penumbra aspiration pump, while arresting proximal flow by balloon inflation.
Methods In patients treated with TSAT, clinical data including National Institutes of Health Stroke Scale (NIHSS) score at admission and the modified Rankin Scale (mRS) score at discharge, as well as procedural data including the Thrombolysis in Cerebral Infarction (TICI) score, procedural time, and complications were analyzed.
Results Thirty-four consecutive patients (19 men (56%); mean age 73 years) were treated with TSAT using a balloon guiding catheter. The patients presented with a mean NIHSS score of 17.4 and 23 (68%) patients received IV tissue plasminogen activator. Median time from groin puncture to successful recanalization was 41 min (range 15–160 min). All patients were successfully revascularized; TICI 2b or better recanalization was achieved in 30 (88%) patients. No patient required an additional procedure such as use of a stent retriever. Procedure-related complications occurred in two (5.9%) patients (vessel injury and guidewire perforation). Symptomatic intracranial hemorrhage occurred in one patient and asymptomatic hemorrhagic infarction occurred in two patients. There were no cases of embolization to new territory (ENT). The mean NIHSS score at discharge improved to 6.1. Sixteen patients (47%) achieved a good outcome with an mRS score of 0–2 at discharge (mean hospitalization period 20 days).
Conclusions TSAT with proximal flow arrest by a balloon guiding catheter is an effective and safe method to achieve good clinical and angiographic outcomes. This method may reduce ENT in the direct aspiration first-pass thrombectomy (ADAPT) technique.
- Thrombectomy
- Stroke
- Technique
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Introduction
Mechanical thrombectomy for the treatment of acute ischemic stroke has recently shown significant advances.1 The use of new revascularization devices and techniques for thrombectomy has improved the recanalization rates and clinical outcomes remarkably. Recent randomized studies have shown the benefits of endovascular treatment for acute ischemic stroke.2–6 Two principal mechanical thrombectomy techniques have been used, including stent retrievers or direct aspiration using a large-bore aspiration catheter. Stent retriever thrombectomy and direct aspiration first-pass thrombectomy (ADAPT) lead to the highest degree of recanalization.7–14
However, embolization to unaffected territories and to distal territories remains a major problem which could affect eventual clinical outcomes.15
The purpose of this report is to describe our initial results with the two-stage aspiration technique (TSAT), which is a combination of proximal blood flow arrest by a balloon guiding catheter and sequential aspiration from the Penumbra 3MAX catheter and the Penumbra 5MAX ACE for vessel recanalization.
Endovascular procedure: TSAT
The TSAT technique is shown in figure 1. A simplified model was initially used to verify whether TSAT functions effectively (figure 2).
Illustration of the two-stage aspiration technique in a middle cerebral artery clot. (A) A 9 F balloon guiding catheter is positioned in the proximal internal carotid artery. Through the balloon guiding catheter, a 5MAX ACE reperfusion catheter is advanced over a 3MAX catheter with a 0.014 inch microwire. Under balloon inflation, a 3MAX catheter and microwire are delivered across the clot and positioned at the M2 segment, and the 5MAX ACE is positioned immediately adjacent to the clot. (B) Only the microwire is removed from the 3MAX catheter and aspiration is applied to the 3MAX by the Penumbra aspiration pump. (C) The 3MAX catheter is slowly withdrawn into the 5MAX ACE while maintaining aspiration from the 3MAX catheter. (D) The 3MAX catheter is removed from the 5MAX ACE and aspiration is immediately applied to the 5MAX ACE by the Penumbra aspiration pump. (E) The 5MAX ACE is then removed while maintaining aspiration to ensure the clot remains engaged in the guiding catheter tip. After the 5MAX ACE is removed from the balloon guiding catheter, the balloon is finally deflated.
Experimental verification of the two-stage aspiration technique with a simple vascular model. Delivering a 0.014 inch microwire across the thrombus and navigating both the 3MAX (white arrow) and 5MAX ACE (black arrow) following the microwire (A). The 3MAX catheter is placed in the distal portion beyond the thrombus (B), and the 5MAX ACE is positioned immediately adjacent to the thrombus (C). Only the microwire is removed from the 3MAX catheter (D), and aspiration is applied to the 3MAX catheter by the Penumbra aspiration pump. The 3MAX catheter is slowly withdrawn into the 5MAX ACE while maintaining aspiration from the 3MAX catheter. The white liquid component (black circle) of the distal portion of the 3MAX catheter is aspirated and disappears (E–G). The 5MAX ACE is then withdrawn while maintaining aspiration by the Penumbra aspiration pump to ensure the clot remains engaged in the catheter tip, the so-called conventional ADAPT technique (H and I).
All procedures were performed under minimal to moderate conscious sedation with a propofol infusion. After femoral puncture with a 9 F sheath, 5000 units of IV heparin were injected. If patients received IV tissue plasminogen activator (tPA) prior to undergoing the procedure, 3000 units of IV heparin were injected. Heparin was used only for the initial bolus injection without any additional injection during the procedure. A 9 F Optimo (Tokai Medical Products, Aichi, Japan) temporary occlusion balloon guiding catheter was advanced with a 6 F JB2 catheter coaxial system and placed at the origin of the internal carotid artery (ICA), usually just distal to the carotid bifurcation. After the presence of arterial occlusion was confirmed by injection of contrast through the balloon guiding catheter, the balloon was initially inflated to arrest the antegrade flow from the ICA. Under roadmap guidance, a Penumbra 5MAX ACE reperfusion catheter (Penumbra, Alameda, California, USA) was advanced to the level of the thrombus coaxially over a 0.014 inch microwire and a Penumbra 3MAX catheter. The 0.014 inch microwire and the 3MAX catheter were advanced very gently across the thrombus into the M2 segment of the middle cerebral artery (MCA). The 5MAX ACE was then gently advanced immediately adjacent to the site of occlusion. At this point the 5MAX ACE catheter was positioned 1–2 mm into the site of occlusion to ensure solid engagement with the thrombus. Then, only the 0.014 inch microwire was removed from the 3MAX catheter and the Penumbra aspiration pump was connected to the 3MAX catheter. Aspiration was applied from the 3MAX catheter for 20–30 s. The 3MAX catheter was then slowly withdrawn into the 5MAX ACE while maintaining aspiration with the Penumbra pump from the 3MAX catheter.
Immediately after removing the 3MAX catheter from the 5MAX ACE, the Penumbra aspiration pump was connected to the 5MAX ACE. Thereafter, the procedure shifted to the conventional ADAPT technique. After a waiting period of 60 s, the 5MAX ACE was slowly withdrawn into the balloon guiding catheter under continuous aspiration with the Penumbra pump. The 5MAX ACE was then slowly removed from the guiding catheter under continuous aspiration with the Penumbra pump, and simultaneous manual aspiration was also performed with a 20 mL syringe through the side port of the balloon guiding catheter to remove any residual thrombus fragments within it.
After the 5MAX ACE was removed from the guiding catheter, the balloon was finally deflated and angiography was performed through the balloon guiding catheter to confirm recanalization of the occluded vessel.
If aspiration failed, the 5MAX ACE and the 3MAX catheter were quickly reinserted up to the level of the thrombus and repeat aspiration was attempted in the same fashion. This process was repeated until successful reperfusion (Thrombolysis in Cerebral Infarction (TICI) 2b/3) was achieved. However, if three passes failed to achieve effective reperfusion, then another option (such as stent retriever) would be considered.
If the occluded vessel was seen in the M2 segment, a PX slim catheter (Penumbra) was used instead of a 3MAX catheter and a 4MAX catheter (Penumbra) was used instead of a 5MAX ACE. Other technical procedures were similar to those described above.
Two important components are included in this technique. One is use of a balloon guiding catheter, which is useful for excellent navigation of a reperfusion catheter to the thrombus and preventing migration of the clot to distal territory by antegrade flow arrest of the carotid artery. The other is two-stage sequential aspiration from a 3MAX catheter and a 5MAX ACE.
Results
From January 2014 to December 2015, 34 consecutive patients with acute ischemic stroke in the anterior circulation were treated with TSAT by proximal balloon inflation in our institutions. The cohort included 19 men (56%) and the mean age was 73 years (range 41–86 years). The average National Institutes of Health Stroke Scale (NIHSS) score at admission was 17.4 (range 1–25). Twenty-three (68%) patients received IV tPA prior to undergoing TSAT. Two patients had ICA cavernous occlusion, 6 patients had ICA top occlusion, 10 patients had M1 proximal occlusion of the MCA (M1P), 9 patients had M1 distal occlusion of the MCA (M1D), and 7 patients had MCA distal occlusion (M2). A combination of a 5MAX ACE and a 3MAX catheter was used in 29 patients (ICA cavernous, ICA top, M1P, M1D, M2) and a combination of a 4MAX catheter and a PX slim catheter was used in 5 patients (M2). The reperfusion catheter was easily navigated past the ophthalmic artery origin without the ledge effect in all cases. All procedures were performed without additional devices such as a stent retriever or combined aspiration/stent retriever thrombectomy. Successful recanalization (TICI score 2b−3) was achieved in 30 (88%) patients. TICI score 3 recanalization was achieved in 15 (44%) patients. The median time from groin puncture to successful recanalization was 41 min (range 15–160 min). There was one parenchymal hemorrhage that resulted in a poor outcome. There were two asymptomatic hemorrhagic infarctions after the procedure. The average NIHSS score on admission was 17.4, which improved to 6.1 by the time of discharge. Sixteen patients (47%) achieved a good outcome, with a modified Rankin scale (mRS) score of 0–2 at discharge (hospitalization period 7–32 days; mean 20 days). In our institution, rehabilitation staff were assigned to determine whether patients could be discharged directly to home according to their state in the hospital. If it was not possible for the patient to live independently at home, the patient was transferred to a rehabilitation hospital.
There were no instances of embolization to new territory (ENT). ENT was defined as emboli observed on post-thrombectomy angiography within previously unaffected territories.
There were two procedural complications (5.9%). One was a patient with an M2 occlusion (case 26) who sustained vessel injury while an attempt was made to advance the 5MAX ACE catheter from the M1 distal segment into the M2 proximal segment of the MCA. When the 5MAX ACE was advanced into the proximal M2 portion beyond the severe curvature of the vessel, the 5MAX ACE was extended on fluoroscopy. Immediately after angiography, extravasation from the vessel was seen. The perforator vessel from the M2 segment had probably been pulled out and resulted in the extravasation. This patient was treated with glue injection into the injured vessel which resulted in M1 distal occlusion, but the clinical findings did not deteriorate. The other was a patient with ICA top occlusion (case 5) who developed M2 segment vessel perforation from the microwire. This patient had a large parenchymal hemorrhage and died after 3 days.
Table 1 shows all of the data for the treated patients. A representative case (no 27) is shown in figure 3.
Procedural and clinical data and outcomes
Patient no 27 with left M1 distal segment occlusion of the middle cerebral artery (MCA) (A). The balloon guiding catheter is positioned at the proximal internal carotid artery and the balloon (arrowhead) is inflated (B). The 3MAX catheter (white arrow) is navigated across the occlusion site and positioned at the M2 segment of the MCA (B and C). The 5MAX ACE (black arrow) is positioned at the face of the occlusion site (B and C). Two-stage sequential aspiration is performed from the 3MAX catheter and the 5MAX ACE (C and D). Carotid angiography shows Thrombolysis in Cerebral Ischemia (TICI) 3 recanalization (E). Procedure time to recanalization from puncture is 31 min.
Discussion
TSAT is a procedure that is a modification of the ADAPT technique.10 The modifications of the conventional ADAPT technique are: (1) use of a balloon guiding catheter in the ADAPT technique; (2) continuous inflation of the balloon during the procedure, such as navigation of the 3MAX catheter and the 0.014 inch microwire across the thrombus, navigation of the 5MAX ACE to the face of the thrombus, direct aspiration of the thrombus, and removing the 5MAX ACE from the guiding catheter; (3) the 3MAX catheter is navigated distal to the thrombus and aspiration is also applied from the 3MAX catheter using a Penumbra aspiration pump; and (4) immediately after removing the 3MAX catheter from the 5MAX ACE, the next aspiration is started from the 5MAX ACE using the Penumbra aspiration pump.
Inflation of the proximal balloon from an early stage during the procedure has three useful advantages. First, it provides excellent support for further advancement of the 5MAX ACE because the guiding catheter is less likely to be pushed back by the anchoring effect of the balloon. Second, it may be possible to reduce the risk of ENT or embolization to distal territory (EDT) during the procedure. Third, it is possible to improve the suction power from the reperfusion catheter or the guiding catheter.
ENT or EDT is one of the important issues in mechanical thrombectomy for the treatment of acute ischemic stroke.15 Recently, a balloon guiding catheter has been used to reduce ENT or EDT during stent retriever thrombectomy.16 ,17 In general, the balloon guiding catheter was placed in the carotid artery. The balloon at the tip of the guiding catheter was then inflated to arrest antegrade blood flow from the carotid artery before the stent retriever was withdrawn, and manual aspiration through the guiding catheter was applied using a 20 mL syringe. This approach was originally proposed to address the high incidence of ENT that has been reported with thrombectomy.18
Some clinical studies of the effectiveness of proximal flow control using a balloon guiding catheter in acute thrombectomy with stent retrievers have been reported, mainly only with stent retriever thrombectomy. Kurre et al 16 reported a very high revascularization rate (TICI 2b/3 of 91%) in 175 occluded vessels and an improvement in ENT to 3.5% from 14% when distal aspiration was used with stent retrievers. Using combined local aspiration with stent retrieval, Humphries et al 18 reported minimal ENT (<5%) with very high rates of revascularization (88% TICI 2b/3) and low rates of symptomatic intracerebral hemorrhage (<5%). Nguyen et al 17 described their experience with the use of a balloon guiding catheter in conjunction with Solitaire FR stent retriever thrombectomy; TICI 3 recanalization was seen more often in cases in which the balloon guiding catheter was used. They also reported that the discharge NIHSS score and 3-month favorable clinical outcome were significantly higher in the balloon-guided catheter group, although the ENT or EDT rate was similar in the two groups.
An in vitro vascular model has also shown that a stent retriever and traditional aspiration thrombectomy result in fragmentation of the embolus during extraction, creating downstream emboli and, potentially, emboli to previously uninvolved vascular territories.15 ,19 ,20
The ADAPT technique may reduce the frequency and number of downstream emboli because it seems to cause minimal clot disruption and fragmentation due to the extraction of the occlusive embolus en bloc with a single pass. However, ENT was noted in 6% of cases in another initial clinical report of the ADAPT technique.21 Even in the ADAPT FAST series, the rate of EDT was also high (10%), but no cases of ENT were observed.11 However the definition of EDT is still unclear. Strictly speaking, if M1 occlusion results in TICI 2b, it is unclear whether a distal branch occlusion was pre-existing or due to EDT. In our series there were no cases in which cerebral infarction appeared in the new area of the distal branch on postoperative diffusion weighted MRI even if TICI 2b on angiography.
In an in vitro study the rate of EDT reached 13%, which is similar to the rates reported in the ADAPT and ADAPT FAST studies.20 In the in vitro study, although clot removal via ADAPT tended to be more efficient for reducing large fragments (200–1000 μm), ADAPT led to high numbers of distal emboli in the size ranges of 100–200, 50–100, and <50 μm.15
In TSAT, proximal flow arrest by balloon inflation plays an important role in successful thrombus aspiration when the microwire and the 3MAX catheter are navigated across the thrombus and the 5MAX ACE is removed while maintaining aspiration to ensure that the clot remains engaged in the guiding catheter tip. A 3MAX catheter is commonly used to support catheterization with a 5MAX ACE reperfusion catheter in the conventional ADAPT technique. If the 3MAX catheter is deployed to the distal artery beyond the thrombus, the 5MAX ACE is easily navigated to face the thrombus. However, there is concern about the migration of the clot when the microwire or the 3MAX catheter passes the clot. In TSAT with a balloon guiding catheter, the microwire and 3MAX catheter can cross the thrombus safely without concern about clot distal migration thanks to the proximal flow arrest during the procedure. In TSAT, if the thrombus is fragmented or migrated to the distal segment of the occluded vessel, the 3MAX catheter placed beyond the thrombus can also aspirate the distal fragmented clot. Given this, TSAT is likely to reduce the frequency of ENT or EDT compared with the conventional ADAPT technique in this procedure.
There is a question about whether aspiration from the 3MAX catheter positioned beyond the thrombus is really functioning in TSAT. In a simple experiment we confirmed that aspiration from the 3MAX catheter was very effective if aspiration was performed using the Penumbra aspiration pump (figure 2). We are confident that the 3MAX catheter is sufficiently useful as the reperfusion catheter in TSAT. The 3MAX catheter may also be effective for the reperfusion catheter, as well as the coaxial catheter of the 5MAX ACE. Navia et al 22 reported the effectiveness of the 3MAX catheter as the reperfusion catheter in endovascular treatment of acute ischemic stroke of distal arteries. They achieved recanalization (TICI 2b–3) in all six cases on the first attempt and did not need to combine treatment with a stent retriever. They showed that both reperfusion catheters were slowly removed under aspiration (3MAX catheter with the aspiration pump and the ACE/ACE 64 catheter with a 60 mL syringe) to decrease the chances of thrombus disaggregation in distal emboli. Furthermore, they proposed that selective catheterization with the ACE/ACE 64 catheter of the proximal segment of the artery to be treated can minimize the chance of stroke in new territories and increase the safety of the procedure.
Two important technical points in TSAT with proximal blood flow arrest need to be considered. The first is to continue inflating the balloon from the time of navigation of the reperfusion catheter to the time of its removal, and the other is never to check the angiography with contrast in the middle of the procedure because there is a risk of moving the thrombus to distal territory by the injection pressure.
There are two problems in TSAT with proximal blood flow arrest using balloon occlusion. One is that cerebral ischemia may be caused by balloon occlusion; however, it seems not to be a problem in many cases because the vessel is initially occluded in acute ischemic stroke. The procedure should therefore be performed as quickly as possible and heparinization may be necessary in this procedure. However, there is no consensus about the use of heparin. It may increase the possible risk of hemorrhagic infarction, but this will need to be examined in a larger study. Another problem is that a 5MAX ACE is too easily navigated to the distal portion by the support power of the anchoring effect with balloon inflation. Therefore, the 5MAX ACE should be advanced up to the M1 distal segment, never to the M2 segment, which might lead to severe vessel injury.
The limitations of the present study are the small sample size, and larger studies are needed to establish the benefits and safety of this procedure.
Conclusion
TSAT with proximal flow arrest using a balloon guiding catheter is effective for the treatment of acute ischemic stroke of the anterior circulation. This approach has allowed us to achieve excellent clinical and angiographic outcomes and may reduce ENT and EDT in acute ischemic thrombectomy. However, larger studies are needed to establish the benefits and safety of this procedure.
References
Footnotes
Contributors HM: Study design, idea of technique, data collection and analysis, manuscript preparation, manuscript editing and guarantor of the whole study. HN, YT, HT: Study design, data collection and analysis. NN: Study design.
Competing interests None declared.
Patient consent Obtained.
Ethics approval This study was approved by the institutional review board of Kishiwada Tokushukai Hospital.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data created during this clinical study are available from the corresponding author.