Optimizing First-Pass Complete Reperfusion in Acute Ischemic Stroke: Pearls and Pitfalls

Acute ischemic stroke (AIS), particularly if caused by a large vessel occlusion (LVO), is a severely disabling, life-threatening disease. In 2015, five major randomized controlled trials have shown the benefit of endovascular treatment (EVT) compared with intravenous alteplase in AIS patients with LVO, ¹ and since then, EVT is considered standard of care. EVT significantly reduces disability in LVO patients and the number needed to treat for reduction of disability by at least one point on the modified Rankin Scale is 2.6. ¹ The safety profile of EVT is excellent, with no significant differences in mortality and symptomatic intracranial hemorrhage compared with intravenous alteplase treatment alone. ¹ Given this powerful treatment option and the low recanalization rates of LVOs with tissue plasminogen activator alone, many physicians, including ourselves, now offer EVT routinely beyond guideline recommendations. On average, every 30-minute delay in recanalization decreases the chance of a good functional outcome by 8 to 14%. ² Thus, reperfusion has to be achieved fast. Reperfusion quality (i.e., how well we open a vessel) is another key determinant of patient outcome: higher expanded treatment in cerebral infarction (eTICI) grades are strongly associated with good patient outcome. ³ The eTICI score reflects the final reperfusion result, but complete recanalization sometimes requires multiple device passes, ⁴ which yields an increased risk of endothelial injury. First-pass effect (i.e., achieving complete revascularization with a single device pass) is an independent predictor for good outcome. Fast and complete reperfusion is also beneficial from an economic standpoint: In the United States, the net monetary benefit per patient is on average $17,000 per 1% increase in the final eTICI IIc/III rate and $10,600 per 10 minutes of time-to-treatment decrease. ^{5 6}

Optimizing Fast First-Pass Complete Reperfusion in Acute Ischemic Stroke: BADDASS

In our opinion, when performing EVT, the BAlloon guide with large bore Distal access catheter with Dual Aspiration with Stent-retriever as Standard Approach” (BADDASS) should be used, as it combines the advantages of primary aspiration, stent retrievers, and balloon guide catheter (BGC) and thus is the most efficient way to reopen an occluded vessel fast and safely. Details of the technique have been described previously. ⁷ The eight key steps of BADDASS are summarized in Table 1 .

Table 1. Key features of BADDASS.

1	Triaxial setup (balloon guide catheter, large bore distal access catheter, microcatheter)
2	Distal placement of a long stent retriever (into preferably inferior M2 division
3	Active push deployment
4	Removing and reloading the microcatheter
5	Applying traction to the stent wire to advance DAC to proximal end of clot
6	Releasing traction off the stent wire
7	Balloon inflation and double aspiration
8	Complete withdrawal of the stent retriever–clot complex and distal access catheter

Abbreviations: BADDASS, BAlloon guide with large bore Distal access catheter with Dual Aspiration with Stent-retriever as Standard Approach; DAC, distal access catheter.

Overcoming High-Grade Carotid Stenosis, Carotid Occlusion, and Pseudoocclusion: Use of Diagnostic Catheters and Wires

Acute stroke patients with tandem lesions (i.e., an occlusion or high-grade stenosis of the extracranial internal carotid artery (ICA) and a combined major intracranial artery occlusion) are challenging to treat. Currently, there is no consensus on the best treatment strategy, and thus, treatment approaches are highly variable. Furthermore, carotid pseudoocclusion (i.e., nonopacification of the vessel due to slow flow caused by a downstream occlusion) commonly mimics extracranial ICA occlusion, since the faint intraluminal opacification caused by slow flow can oftentimes not be appreciated. In case of a tandem lesion, clot retrieval can be approached in two ways: either the intracranial clot is removed first and—if necessary—a carotid stent is put in place after clot retrieval or the two steps are performed in reverse order. A third option is to perform both procedures in parallel by placing the stent retriever first and using the wire of the stent retriever to place a carotid stent. If the intracranial clot is retrieved first, there is, in theory, a small risk of dislocation of thrombotic material, which has accumulated in the poststenotic ICA due to slow flow, into the anterior cerebral artery. However, by our experience, this risk is almost negligible, and clot retrieval prior to ICA stenting has two major advantages: (1) brain ischemia and infarction is caused by the more distal clot, and fast retrieval of this clot minimizes infarct progression, and (2) when the BGC is placed beyond the ICA stenosis, it can “dotter the lesion,” which, in some cases, is sufficient to dilate the ICA stenosis such that stenting after clot retrieval is not necessary anymore.

1. High-grade stenosis at the ICA origin with normal and patent distal vessel lumen:

To navigate fast and safely past a high-grade ICA origin stenosis with normal and patent distal vessel lumen ( Fig. 1a ), a diagnostic wire (e.g., 0.035″ wire, Fig. 1b ) and a diagnostic catheter ( Fig. 1c ) should be used, as they provide the necessary stiffness to overcome the stenosis. Once the diagnostic catheter has passed the stenosis, a BGC is placed in the cervical ICA ( Fig. 1d ) and the procedure is continued as usual.

Fig. 1.

In case of a high-grade stenosis at the internal carotid artery (ICA) origin with a normal poststenotic vessel ( a ), a diagnostic wire (black) is navigated through the stenosis ( b ). A diagnostic catheter (purple) is then advanced past the stenosis ( c ). Once this is done, a balloon-guide catheter (gray) can be placed in the proximal ICA ( d ) and the procedure is continued as usual.

2. Pseudoocclusion at the ICA origin:

When a flame-shaped contrast extension into the ICA origin is seen ( Fig. 2a and Fig. 3a ), it is not clear whether this represents real extracranial occlusion (usually due to dissection) or pseudoocclusion caused by slow flow due to the intracranial occlusion. Multiphase computed tomography angiography (mCTA) is the advanced imaging modality of choice in acute ischemic stroke ⁸ and can help distinguish these two entities: In pseudoocclusion, delayed contrast appearance in the affected ICA can be usually depicted in the delayed phases and the vessel lumen appears slightly hyperdense. If this can be seen ( Fig. 2a ), a pseudoocclusion is more likely and a diagnostic wire ( Fig. 2b ), followed by a diagnostic catheter ( Fig. 2c ), should be advanced past the ICA origin into the proximal ICA. Then, a balloon-guide catheter is navigated past the origin and placed in the proximal ICA ( Fig. 2d ). As soon as this is done, aspiration from the balloon-guide catheter after balloon inflation should be initiated to remove the clotted blood that has accumulated in the ICA due to slow flow ( Fig. 2e ).

Fig. 2.

Pseudoocclusion with faint contrast staining (light red) in the internal carotid artery (ICA) in the second and third multiphase computed tomography angiography phase ( a ). A diagnostic wire ( b ), followed by a diagnostic catheter ( c ) and a balloon-guide catheter ( d ) are advanced past the ICA origin and placed in the proximal ICA. As soon as the balloon-guide catheter is placed properly, aspiration is applied (black arrow) to remove thrombotic material that has accumulated in the ICA due to slow flow ( e ).

Fig. 3.

When no contrast staining in the internal carotid artery (ICA) can be appreciated ( a ), it is not clear whether the image constellation represents a real or a pseudoocclusion. In such cases, the risk of clot fragmentation and distal embolization should be minimized by using a microwire ( b ) and a distally fitted microcatheter (green, c ) which allows for facilitated, atraumatic navigation of the distal access catheter (DAC) ( d ) past the ICA origin. Once the DAC (blue) is placed ( e ), and while advancing it ( f ), suction should be immediately applied to capture clot fragments that could have potentially been sheared off during the previous steps (black arrows). A balloon-guide catheter is then advanced and placed in the cervical ICA ( g ) and the procedure can be continued as usual.

Possible Occlusion or Pseudoocclusion at the ICA Origin

If, however, mCTA is not available or for other reasons it is not possible to discriminate between true and pseudoocclusion ( Fig. 3a ), a less traumatic approach should be chosen to minimize the risk of dislocation and fragmentation of an ICA thrombus with subsequent distal embolization. Therefore, a microwire ( Fig. 3b ) instead of a diagnostic wire is advanced over the site of the suspected occlusion and a distally fitted microcatheter (a microcatheter with a bulbous part that is designed to match the inner lumen of the distal access catheter [DAC]; e.g., the Wedge microcatheter, Microvention, Tustin, CA; Fig. 3c ) is used to facilitate navigation of the DAC past the ICA origin ( Fig. 3d ). The DAC is connected to suction as it is crosses through the stenosis to capture potentially fragmented thrombotic material that has been sheared off from the ICA origin and can be used to clear out residual clot from the ICA ( Fig. 3e ). The procedure can then be continued as usual. Once the DAC is beyond the stenosis, in our experience, it is relatively easy to advance the BGC over the DAC to in the proximal ICA ( Fig. 3f, g ).

Sometimes, especially in cases with tough, calcified plaque at the ICA origin, the aforementioned, less traumatic approach fails because the microwire and microcatheter are not stiff enough and slip off ( Fig. 4a ). In such cases, a stiffer diagnostic wire and diagnostic catheter, which provide more stability, can be used. Once the catheter is positioned, the diagnostic wire ( Fig. 4b ), followed by the diagnostic catheter ( Fig. 4c ), and a BGC ( Fig. 4d ) are advanced past the occlusion site, and suction immediately applied to the BGC to clear out clotted blood that might have accumulated in the ICA ( Fig. 4e ). This approach carries a small risk of ICA dissection, but it is the only possibility to access the occluded intracranial vessel. Not infrequently, the clot at the ICA origin will encase the guide catheter; in such cases, a balloon is not even necessary to achieve flow arrest, and a regular guide catheter can be used. In cases of chronic carotid occlusions, where the ICA cannot be accessed, a contralateral approach is possible through the anterior communicating artery.

Fig. 4.

Sometimes, a less traumatic approach is not possible because the microwire and distally fitted microcatheter (green) are not stiff enough and will slip off ( a ). In such cases on has to switch to a different approach (arrow), in which a stiffer diagnostic wire and diagnostic catheter (purple) are used, which provide more stability. The wire is navigated past the site of occlusion ( b ), followed by the diagnostic catheter ( c ). Then, a guide catheter (either a balloon guide catheter as shown in d or a regular guide catheter) is advanced and aspiration is applied to clear out clot ( e ) from the internal carotid artery.

Gaining Access in Patients with Challenging Arch Anatomy—Quadraxial Approach and Appropriate Catheter Choice

Inability to achieve common carotid access is a frequent reason for reperfusion delays and endovascular therapy failure. Particularly accessing the left common carotid artery can be difficult when there is an acute angle at the vessel origin. In this case, we recommend using a quadraxial approach with an additional 8-Fr shuttle, BGC, a Simmons-2 diagnostic catheter, and a stiff wire (e.g., Terumo advantage,). This provides more stability to the entire system once carotid access has been established ( Fig. 5 ). Alternatively, a transradial approach can be used, as most left common carotids that are hard to access through the transfemoral route are easily accessed transradially and there are reports of BGC use through the radial artery. ⁹

Fig. 5.

Acute angles at the left common carotid artery origin often require a shuttle in addition to the balloon guide catheter, a Simmons-2 distal access catheter and stiff diagnostic guidewire (quadraxial approach).

The Simmons-2 catheter's shape is optimized for accessing the common carotid artery in case of an acute angle at the vessel origin and its tip can usually be positioned in the left common carotid artery without difficulty. For a slightly less acute angle (which we see more frequently), we chose the VTK catheter, which can be considered the “work-horse” of left common carotid artery access. Once the catheter tip is in its intended position, it is slightly pulled back to straighten the angle at the common carotid origin. This usually allows us to advance the BGC over the common carotid artery origin ( Fig. 6 ).

Fig. 6.

Once the tip of the Simmons-2 catheter is placed in the proximal left common carotid artery, the catheter is slightly pulled back to straighten the angle at the vessel origin ( a , arrow). This allows easy advancement of the balloon guide catheter because the angle it has to overcome is less acute ( b ).

Usually we advance the wire as far distally as possible, sometimes even up to the petrous segment to improve the system's stability. If, despite these measures, support for advancing the BGC is insufficient, the wire can be replaced by an even stiffer wire (e.g., Terumo Glidewire stiff or Terumo Glidewire advantage). Pushing the Simmons-2 or VTK catheter further forward once its tip is positioned in the left common carotid artery has to be avoided, as this will lead to dislocation of the whole system including the guidewire into the aortic arch ( Fig. 7 ). Radial access should be considered the first alternative if the quadraxial approach fails and can be a good first-line approach in patients with known severe atherosclerosis of the femoral arteries and abdominal aorta. Sometimes, the angle at the left common carotid artery origin is such that access is very challenging when coming from the femoral artery but easy from the radial artery. Only in the rare case that both the femoral and radial approach fail, a direct carotid puncture is necessary.

Fig. 7.

Once its tip is properly positioned in the left common carotid artery, one should not push the Simmons-2 catheter further forward ( a , arrow), as this will lead to dislocation of the whole system including the guidewire into the aortic arch ( b , c ).

The Future of EVT: Tailored Thrombectomy Devices, Simulation Training, and Solving the Challenge of Getting the Right Patient to the Right Hospital

Current endovascular treatment techniques are already fairly sophisticated, and the scope for further improvement is probably limited. We personally think the greatest potential for improvement lies in developing effective “Plan B” techniques: what should be done if BADDASS has failed and how fast should we switch to “Plan B?” One major problem is that only a small fraction of AIS patients with LVO reach the angiography table. To increase the denominator (i.e., the EVT-eligible treatment population), existing systems of care have to be reorganized and transport paradigms individually tailored to local geography and infrastructure. ^{10 11 12} Fast first-pass complete reperfusion, which is the focus of this review article, remains a cornerstone successful stroke treatment. However, nowadays improving prehospital stroke management and intrahospital workflows (e.g., bypassing the CT scanner to get the patient faster to the angiography table: the so-called one-stop management) ^{13 14} yield an even greater potential for improving patient outcomes.

Conclusion

In conclusion, fast first-pass complete reperfusion should be the ultimate goal when performing EVT in patients with AIS. Ideally, a combined technique (such as BADDASS) should be used, as it yields the greatest chance to achieve this goal and, thus, improve patient outcome. Overcoming high-grade carotid stenosis or (pseudo-)occlusions and tortuous anatomy can be challenging and can be mastered by using stiffer, diagnostic wires/catheters and distally fitted microcatheters. Difficulties to gain access at the aortic arch level can be overcome by using a quadraxial approach. However, the bottleneck in neurointerventional stroke treatment nowadays is not treatment technique itself but the organization of stroke care: how to get the right patient to the right hospital as fast as possible.