Background The development of new revascularization devices has improved recanalization rates and time but not clinical outcomes. We report our initial results with a new technique utilizing a direct aspiration first pass technique with a large bore aspiration catheter as the primary method for vessel recanalization.
Methods A retrospective evaluation of a prospectively captured database of 37 patients at six institutions was performed on patients where the ADAPT technique was utilized. The data represent the initial experience with this technique.
Results The ADAPT technique alone was successful in 28 of 37 (75%) cases although six cases had large downstream emboli that required additional aspiration. Nine cases required the additional use of a stent retriever and one case required the addition of a Penumbra aspiration separator to achieve recanalization. The average time from groin puncture to at least Thrombolysis in Cerebral Ischemia (TICI) 2b recanalization was 28.1 min, and all cases were successfully revascularized. TICI 3 recanalization was achieved 65% of the time. On average, patients presented with an admitting National Institutes of Health Stroke Scale (NIHSS) score of 16.3 and improved to an NIHSS score of 4.2 by the time of hospital discharge. There was one procedural complication.
Discussion This initial experience highlights the fact that the importance of the technique with which new stroke thrombectomy devices are used may be as crucial as the device itself. The ADAPT technique is a simple and effective approach to acute ischemic stroke thrombectomy. Utilizing the latest generation of large bore aspiration catheters in this fashion has allowed us to achieve excellent clinical and angiographic outcomes.
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Acute ischemic stroke continues to be a significant burden on worldwide health systems and remains one of the leading causes of disability and death. Improved clinical outcomes have been correlated with early vessel recanalization.1 The development of new revascularization devices have resulted in faster and better recanalization rates, yielding better clinical outcomes compared with earlier devices.2 ,3 These newer devices are available at much higher costs than other comparative endovascular devices. We believe that the push for utilizing the latest generation of devices needs to focus on quality of thrombectomy rather than ability to recanalize. We report our initial results with a new technique utilizing a direct aspiration first pass technique with a large bore aspiration catheter as the primary method for vessel recanalization.
Retrospective analysis from a prospectively captured database was gathered on the first patients undergoing stroke thrombectomy with the ADAPT technique at the Medical University of South Carolina, Swedish Medical Centre, Vanderbilt University, Erlanger Medical Centre, Stonybrook University, and University at Buffalo using an institutional review board approved protocol.
All operators selected patients for thrombectomy according to their usual protocol (figure 1). Access to the cerebral vasculature required a 6 French Neurosheath, usually a Neuron 088 Max (Penumbra, Oakland, California, USA). This was advanced as far distally into the internal carotid artery as was safely possible, usually to the skull base or petrous segment of the internal carotid artery. For posterior circulation thrombi, the Neuron 088 was navigated into the largest caliber vertebral artery and positioned into the distal V2 segment. The largest caliber aspiration catheter that the vessel would accommodate was selected for each case, usually a Penumbra 5 Max reperfusion catheter (Penumbra) for M1 or carotid terminus occlusions. The 5 Max was advanced to the level of the thrombus over any microcatheter and microwire the operator chose, but most commonly a Velocity microcatheter (Penumbra) over a 0.016 inch Fathom wire (Boston Scientific Corp, Naidich, Massachusetts, USA). This triaxial system readily negotiated the ophthalmic bend at the carotid siphon. Under roadmap guidance, the wire and microcatheter were navigated past the thrombus, most commonly into a middle cerebral artery post bifurcation branch. Over this platform, the larger 5 Max catheter was delivered and positioned immediately adjacent to the site of occlusion. The microcatheter and wire were removed. Aspiration was applied by either 20 or 60 ml syringe or use of the Penumbra aspiration pump that is part of the Penumbra system.4 Inability to draw back on aspiration confirmed the optimal position of the 5 Max catheter abutting the thrombus. At this point, the catheter was slightly advanced to ensure firm engagement with the thrombus. The 5 Max catheter was then slowly withdrawn while maintaining aspiration. Aspiration was also applied to the sideport of the Neuron 088 Max to prevent dislodging the thrombus from the 5 Max aperture as it is withdrawn into the sheath. If aspiration failed, the 5 Max was rapidly reinserted up to the thrombus and a repeat aspiration attempted or the local aspiration with stent retriever was performed.5 In smaller caliber or more distal vessels, the technique can be employed with either a 4 Max or 3 Max reperfusion catheter (Penumbra).
Specific parameters captured included age, gender, National Institutes of Health Stroke Scale (NIHSS) score at presentation, time to presentation from last normal, and modified Rankin Scale score at discharge, as this technique has emerged so recently that 90 day follow-up is not available. The average hospital discharge NIHSS score was calculated excluding any patients that expired during hospitalization. The modified Rankin Scale score data were obtained from the neurology clinic record. Radiological and angiographic imaging was reviewed to document the location of the vascular occlusion, Thrombolysis in Cerebral Ischemia (TICI) flow post procedure, and procedural complications. Recanalization time was defined as time from groin access to achieving at least TICI 2B flow within the affected territory.
From November 2012 to March 2013, 37 consecutive cases of acute ischemic stroke were treated with the ADAPT technique in six institutions: 30 involving the anterior circulation and seven involving the basilar artery. Table 1 contains all of the data for the treated patients. Notably, the time from groin puncture to at least TICI 2b recanalization was 28.1 min, with all cases successfully revascularized. TICI 3 recanalization was achieved 65% of the time. On average, patients presented with an admitting NIHSS score of 16.3 and improved to 4.2 by the time of discharge. There was one procedural complication. There were two patients that died from parenchymal hematomas the following day.
The direct aspiration technique alone was successful in 28 of 37 (75%) patients although six cases had large downstream emboli that required additional aspiration. The use of the large bore aspiration catheter alone to achieve complete recanalization was successful in 22 of 38 (57%) cases. Nine cases required the additional use of a stent retriever to achieve recanalization. One case required the addition of a Penumbra aspiration separator to achieve recanalization. One case had an underlying atherosclerotic lesion which, while initially recanalized with direct aspiration very quickly, ultimately required a stent to maintain patency.
There were five deaths before hospital discharge, two related to reperfusion hemorrhage and the remaining three related to cerebral infarction. There was one procedural complication in a patient with a basilar occlusion that resulted in a small subarachnoid hemorrhage, but not worsening in clinical examination.
We found the ADAPT technique to be significantly faster and more efficacious than our previous published thrombectomy experience5 or any series reported in the literature.2 ,3 ,6 Employing this technique, acceptable recanalization (>TICI 2b) was achieved in all patients, as fast as 7 min from groin puncture. The rate of TICI 3 recanalization was also noted to be significantly better than any previously reported. The efficacy and speed of recanalization with this technique likely contributes to the rapid neurological improvement and high rate of patients with good neurologic outcomes at discharge. In addition, when this technique is successful it eliminates the need to introduce a stent retriever or penumbra separator devices, leading to an overall much lower procedure device cost.
Five patients (13.5%) died while in hospital, of whom three were older than 80 years of age, which has been reported to be associated with worse outcome.7 Two patients experienced parenchymal hematomas several hours after the thrombectomy and died. The cases occurred in different hospitals with different operators and were remote from the thrombectomy. In both cases, the patients had a pre-existing infarction approximating one-third to one-half of the middle cerebral territory, but were treated for various reasons. All hemorrhages occurred in the region of infarction that was present prior to thrombectomy. The symptomatic hemorrhage and mortality rates observed are similar to other reported studies for this disease and therapy.2 ,3 One procedural vessel injury resulting in a small amount of subarachnoid hemorrhage occurred in an elderly patient with a basilar occlusion and was felt likely to be related to underlying atherosclerosis.
Distal access catheters from a variety of manufacturers are now routinely utilized to deliver catheters and devices into the distal intracranial circulation. The 5 Max aspiration catheter is the most prevalent catheter we have used in the setting of large vessel occlusions, and has significantly increased the ease and speed of navigation of a large bore catheter into the intracranial circulation. The ADAPT technique differs from prior aspiration methods as it focuses on engaging and removing the clot in its entirety, rather than the use of the separator that was designed to macerate the thrombus and clear the tip of the aspiration catheter. Historically, due to the challenges with tracking an aspiration catheter into the intracranial circulation, catheters had to be telescoped with other catheters together or other tricks employed to advance through the siphon.4 ,8–12 However, the superior trackability of the 5 Max compared with the prior Penumbra 054 has given us the confidence to attempt direct aspiration alone without the fear that it will cost significant time and risk to the patient if intracranial access is lost. The 5 Max also provides a platform for direct aspiration using the catheter itself as the primary device or as a conduit for other devices, such as smaller aspiration catheters for direct aspiration in more distal branches (M2, P2, or P3, for example) or stent retrievers, balloons, or stents should the primary strategy not be successful in achieving recanalization.
Direct aspiration of thrombus with intermediate catheters has been described previously.11 ,13 In these reports direct aspiration was performed not as a primary strategy but rather as an alternative technique when more conventional strategies had already been attempted and exhausted. Kang et al previously reported a primary aspiration technique, but with more modest results likely due to smaller caliber and older technology aspiration catheters.14 They also involved older generations of intermediate catheters, such as the distal access catheter (Concentric Medical) and the 041, and 032 family of Penumbra reperfusion catheters (Penumbra) which have been supplanted by newer iterations. The increased internal diameter of the 5 Max aspiration catheter allows for an increased surface area that provides more optimal contact at the catheter tip–thrombus interface. In addition, it is more capacious along its proximal segment, increasing its luminal volume and thereby resulting in an increased aspiration capacity over prior versions of aspiration catheters.
The modifications made to the Max series catheters likely contribute to the ability to engage the thrombus and remove it as a single specimen while minimizing fragmentation and the creation of distal emboli (figures 2⇓–4). There were no cases of emboli to new territories, which has been reported to occur in up to 14% of cases with stent retrievers.2 ,3 While we did experience some fragmentation of thrombus in the downstream territories, they were usually large macromolecular fragments that lodged in the proximal M2 branches that could then be removed with the initial 5 Max or a 3 Max catheter with subsequent TICI 3 flow. This is contrary to the approach with the use of a separator, where the fragments appear to be micromolecular and lodge in innumerable small distal M4 branches that are not well suited for mechanical thrombectomy and also have less potential for collateralization. This phenomenon has recently been described with an in vitro model where all current thrombectomy devices demonstrated varying size and number of downstream emboli.15
These observations address a critical component in our evolution of conceptualizing stroke thrombectomy in that we have moved beyond the success of recanalization to the quality of the recanalization. This technique raises the bar for neurointerventionalists; we are no longer satisfied in simply achieving recanalization, but rather should focus on achieving optimal recanalization to maximize the likelihood that the patient will achieve a good functional outcome. This implies that we need to focus on the effect of showering downstream emboli to the involved territory, as has been reported in an in vitro model and clinically.2 ,3 ,13 The ADAPT technique is remarkable for the ability to usually remove the offending thrombus whole or in large fragments engaged in the end of the aspiration catheter (figure 1).
The performance of the 5 Max to rapidly and repeatedly access the intracranial circulation coupled with very fast and efficacious thrombectomy times have driven us to alter our approach to stroke thrombectomy procedure. Due to the brevity of the procedure, we no longer routinely place a bladder catheter or an arterial line prior to the procedure, unless easily obtained. We can monitor blood pressure with arm cuff pressures monitored every 2 min. Perhaps most importantly, the majority of these procedures were also performed with moderate sedation rather than general anesthesia, which had previously been our preferred method. The ADAPT method anecdotally appears less painful to the patient compared with thrombectomy attempts with MERCI or Penumbra separators which minimize patient movement to stimuli during the procedure. In addition, since these emergent procedures are often performed after hours in patients with a compromised pre-intervention neurological examination, the anesthesiology team is generally reluctant to extubate patients on the table. The impact on clinical outcomes from this step alone should not be overlooked, as it is well shown that thrombectomy patients’ postprocedural intensive care unit stays are often complicated, with a significant likelihood of pneumonia, other nosocomial infection, deep vein thrombosis, or other complicating factor in patients who undergo general anesthesia with endotracheal intubation.16–19
There are significant limitations to this study, including the small initial experience population and retrospective nature. The limited follow-up does not allow us to project to long term clinical outcomes. While discharge follow-up outcome data rather than 90 day outcome data are a limitation to this study, it would likely only bias the results in fashion against the technique. The absence of a core laboratory adjudicate angiographic results confers a bias to better angiographic outcomes than may be truly present.2 ,3 The absence of procedural complications while achieving superior rates of TICI 3 recanalization, fast procedure times, and the fact that this method was performed at multiple institutions belies the simplicity and ease with which this technique is employed and describes the success of the initial experience.
In conclusion, the ADAPT technique is a simple and effective approach to acute ischemic stroke thrombectomy. Utilizing the latest generation of large bore aspiration catheters in this fashion has allowed us to achieve excellent clinical and angiographic outcomes.
Contributors Each author listed should receive authorship credit based on material contribution to this article, revision of this article, and final approval of this article for submission to this journal.
Competing interests None.
Ethics approval Retrospective analysis from a prospectively captured database was gathered on the first patients undergoing stroke thrombectomy with the ADAPT technique at the Medical University of South Carolina, Swedish Medical Centre, Vanderbilt University, Erlanger Medical Centre, Stonybrook University, and University at Buffalo, using an institutional review board approved protocol
Provenance and peer review Not commissioned; externally peer reviewed.
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