Catheter system capable of improving cerebral artery aspiration

Abstract

A distal entry point of a brain aspiration catheter for obtaining access to carotid and cerebral arteries in the brain of a patient and aspirating one or more intracranial clots from the cerebral arteries during an endovascular procedure comprises: a soft distal tip region having a distal length sufficient to extend from a first or second level arterial segment or equivalent of the cerebral artery to the upper carotid artery vessel, the distal tip region having a distal length sufficient to extend from the first or second level arterial segment or equivalent of the cerebral artery to the upper carotid artery vessel; the rigidity of the first-stage or second-stage arterial section of the cerebral artery enables the first-stage or second-stage arterial section to move, and the outer diameter of the first-stage or second-stage arterial section is 6F- And a proximal region having a stiffness greater than a stiffness of the flexible distal tip region, the proximal region having a length sufficient to extend out of the patient through the distal entry point.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 202080060050.2, which is based on international application PCT / CA2020 / 051026, filed on July 24, 2020, and is entitled “Catheter system capable of improving cerebral artery pumping.” Technical Field

[0002] The present invention describes catheter systems and methods for accessing the brain during endovascular / neurointerventional procedures for treating ischemic stroke. More specifically, the invention describes catheter systems that enable faster and improved access to cerebral vasculature, as well as improved access and aspiration of blood clots from the cerebral vasculature of patients suffering acute ischemic stroke due to medium or large vessel occlusion. Background Art

[0003] The human body is an extensive network of blood vessels, including a system of veins and arteries that circulate blood throughout the body. The onset and / or progression of flow restrictions within the circulatory system can lead to serious medical conditions, the most serious of which are myocardial infarction and ischemic stroke. Treatment for both of these conditions (and others involving the circulatory system) continues to evolve, with many new technologies and devices being used to achieve various treatments.

[0004] It is well known that ischemic stroke caused by a blood clot obstruction in the brain can be treated by advancing a catheter system to the affected site, thereby initiating various procedures to treat the problem. Known procedures include deploying catheters of various designs, used alone and / or in combination with other catheters, stents, and clot retrieval devices, to access and remove the clot.

[0005] For background, when a patient experiences a severe ischemic stroke, parts of the brain distant from the occlusion experience a dramatic decrease in blood supply, affecting the function of neurons across a large area. This decrease in blood supply can cause the patient to experience symptoms, lead to the death of that brain region, and / or put that region at risk of death if not treated quickly. Depending on the location and size of the occlusion, the patient will experience a variety of symptoms, and the severity of the symptoms ultimately determines how the physician chooses to intervene, or not.

[0006] Delays in the time to effective treatment often result in increased neuronal death. Table 1 shows that, in the specific context of acute ischemic stroke, the speed or rate of neural circuit loss in typical large vessel supratentorial acute ischemic stroke can be very rapid.

[0007] Table 1 - Estimated Rate of Neural Circuit Loss in Typical Large Vessel Supratentorial Acute Ischemic Stroke

[0008]

[0009] The numbers presented above represent an average and are known to be highly variable, often depending on the availability of blood supply to the ischemic area via collateral channels. Several factors, including delays in making the decision, initiating the endovascular procedure, and delays during the procedure, any of which can be on the order of mere minutes, can significantly impact neural circuit loss and ultimately patient outcome.

[0010] The paper "Analysis of workflow and treatment time in endovascular treatment of acute ischemic stroke and the impact on outcomes: results of the SWIFT PRIME randomized controlled trial" (Radiology. 2016 Jun;279(3):888-97. doi:10.1148 / radiol.2016160204. eBook April 19, 2016), incorporated herein by reference, quantitatively demonstrated that patient outcomes were clearly improved with rapid reperfusion. In particular, the study concluded that "aggressive time goals may contribute to an efficient workflow environment." Furthermore, the study specifically quantified that patients had significantly improved functional independence when treated rapidly (i.e., within 2.5 hours of stroke onset).

[0011] Importantly, it is now known that an efficient workflow in recanalization procedures, where effectiveness and efficiency of the procedure are important, can provide better outcomes.

[0012] Initially, when diagnosing an ischemic stroke to evaluate possible treatments, doctors know the location of the blood vessel occlusion, the size of the occlusion, the location of any dead brain tissue (the "core"), and the size and shape of brain tissue that was affected by the ischemic event but may be preserved (the "penumbra").

[0013] The penumbra, the tissue surrounding an ischemic event, may survive for hours after the event due to perfusion via collateral arteries. Collateral arteries can provide enough oxygen, nutrients, and / or irrigation to the penumbra tissue to prevent its death for a period of time.

[0014] In response to acute ischemic stroke, endovascular treatment of acute ischemic stroke caused by occlusion of large vessels in the anterior circulation has now become the standard of care for patients under certain criteria. That is, patients who present with specific symptoms (i.e., stroke symptoms of a specific severity) will benefit from early and rapid endovascular intervention to open the occluded blood vessels. Typically, during various endovascular treatments, the physician advocating active treatment with medical measures will pass a series of catheters from the patient's groin through the femoral artery, the descending aorta, to the aortic arch and into the carotid and cerebral arterial systems until the clot is located. After access to the clot is achieved by placing the catheter, a clot recovery and / or clot aspiration device is deployed through the catheter, where the clot is extracted and / or aspirated from the clot site. Access can also be obtained from other areas, including increasingly the radial artery and to a minimum through the carotid artery.

[0015] There are many anatomical and situational factors that influence the severity and ultimate management of ischemic stroke. Importantly, as discussed above, although a blood clot may severely impair blood flow to the ischemic area, some blood flow may reach the ischemic area if collateral arteries function to at least partially perfuse the affected area.

[0016] The most common large vessel occlusion treated with endovascular techniques is the M1 segment of the middle cerebral artery (MCA). When a patient experiences an M1 occlusion, the area supplied by the M1 experiences a dramatic decrease in blood supply. As a result, distal neurons function poorly, and the patient experiences symptoms.

[0017] Recanalization procedures utilize a variety of devices and techniques to access the clot and achieve its removal. Typically, the endovascular surgeon will have a variety of tools at their disposal, including a wide range of guide catheters, balloon guide catheters, guidewires, diagnostic catheters, microcatheters, microwires, stents, and other tools, each with properties, features, and functions that are effective for different surgical and patient presentations. Most, if not all, of the aforementioned tools are disposable, and they are also expensive. Therefore, in situations where similar or better outcomes can be achieved using faster procedures (i.e., fewer steps), fewer tools, and / or at a lower cost, there is an incentive to continue designing new tools that can achieve these goals. Additionally, minimizing the number of catheters used can help reduce the potential for errors and / or adverse outcomes that can result from complex procedures.

[0018] As previously mentioned, endovascular access to the brain is typically performed through the patient's groin region by puncturing the common femoral artery and inserting an arterial sheath to access the arterial vasculature.

[0019] Then, under fluoroscopic (X-ray) guidance, a catheter system (usually a coaxial system including a guiding catheter (GC) or balloon guiding catheter (BGC), a diagnostic catheter (DC), and a guidewire (GW)) is passed through the descending aorta to the aortic arch.

[0020] The diagnostic catheter has a shaped tip to hook the vessel of interest and is advanced to the desired artery with the help of a guidewire. Subsequently, a guiding catheter / balloon guiding catheter is advanced over the diagnostic catheter so that the tip of the GC / BGC is located in the desired carotid artery.

[0021] At this stage, the diagnostic catheter and wire are removed so that the GC / BG provides direct access from outside the body to the carotid artery of interest. It should be noted that the GC / BGC takes up space, and its external or outer diameter (OD) and internal or inner diameter (ID) limit the size of all further devices advanced through the GC / BGC. The maximum OD of the GC / BGC is dictated, inter alia, by the ID of the arterial sheath.

[0022] A catheter designed for intracranial access is then advanced through the guiding catheter. This typically involves one of two approaches:

[0023] a. Microcatheters and microfilaments; or,

[0024] b. Triaxial system, including distal access catheter (DAC), microcatheter and microwire.

[0025] For method a: Once the microcatheter and microwire have passed through the clot, remove the microwire and slowly deploy the stent retriever through the clot. While aspirating through the guiding catheter (and inflating the balloon if using a BGC), remove the stent retriever to capture the clot and establish reperfusion.

[0026] For method b, a DAC is placed near the clot. In method b1, a microcatheter is used to penetrate the clot, and after the microwire is removed, a stent retriever is deployed. The stent retriever and DAC are then typically removed together, with suction being drawn through the DAC. In method b2, the stent retriever is not used, and direct attempts to capture the clot are made by suction through the DAC.

[0027] Advancing a catheter and / or stent retriever system to the clot and performing the procedure involves a number of issues and / or limitations, including the highly complex and variable physical dimensions of the patient's anatomy.

[0028] For example, a particular consideration is that stroke commonly affects the elderly, and with aging, the tortuosity of the aortic arch often increases, which can often make access to the carotid artery difficult. In particular, the combination of aortic arch and carotid artery with high tortuosity can make it difficult to advance a catheter system, as the high bend angle and friction can cause the catheter to prolapse into the ascending aorta, preventing advancement through the desired vessel. In other words, when pushing a catheter system through a sharp bend, the system will seek the path of least resistance and may ultimately be pushed in the wrong direction. Furthermore, the tortuosity may prevent further advancement of the catheter. The combination of a sharp bend and the origin of another artery, as is commonly seen in the stalk segment of the internal carotid artery, can be a common location where such a catheter may become stuck.

[0029] Another consideration is the size of the available catheter system and issues surrounding the need to provide GC / BGC support for the smaller catheters to advance them. Since the smaller catheter is supported by the larger catheter, the OD / ID of the smaller catheter, the inner catheter is limited by the ID of the larger supporting catheter.

[0030] Catheter performance

[0031] As mentioned above, there are two types of catheters used in brain surgery: diagnostic catheters and guide catheters. Diagnostic catheters are typically those used to access the area of interest, while guide catheters are used to support and guide additional devices. Additional devices include diagnostic catheters, guidewires, balloons, microcatheters, stents, microwires, etc. These devices may require specific surgical techniques.

[0032] Typical diagnostic catheters range from 4F to 6F (French) and are 65-125cm in length. They may have a braided wall structure and often have a soft tip with various shapes formed into the tip, often used to enhance hooking of specific blood vessels. DCs can be designed with different stiffness and can be relatively soft or relatively stiff.

[0033] Guide catheters are typically larger (e.g., 6-9 French), typically 80-100 cm in length. They often have a reinforced structure with a significantly stiffer shaft to provide backup (i.e., posterior) support for advancement of any additional equipment listed above. However, guide catheters can typically only be advanced to the carotid artery in the neck, as a combination of their stiffness, vessel narrowing, and vessel tortuosity prevent further advancement.

[0034] From an anatomical perspective, the catheter must traverse different regions of the vasculature, namely the abdominal and thoracic vasculature between the femoral artery and aortic arch (approximately 50-75 cm), for example, where the catheter enters the body via a groin puncture, the neck vasculature (approximately 15-20 cm), and the head / brain vasculature (approximately 10-15 cm). The vessels gradually narrow, from 2.5 cm in the aorta down to 3 mm and less in the cerebral vessels.

[0035] A variety of features and geometries can be designed into diagnostic and guide catheters, including:

[0036] Trackability – the ability of a catheter to glide over a guidewire, particularly through tortuous (tightly curved) vessels.

[0037] Push performance – the ability to advance the catheter tip or head based on operator input from a hub (i.e., outside the body).

[0038] • Torsion performance - the ability to control the catheter tip based on operator twisting at the hub.

[0039] Tip or Head Shape - The shape of the catheter tip or head will help the operator maneuver the distal tip of the catheter through specific anatomical features. For example, a diagnostic catheter may have a shape that is flat, straight, has a simple curve, a complex curve, a reverse curve, or a hyperbolic curve. Such shapes can be classified as simple or complex.

[0040] Stiffness – The ability of the catheter to bend around curves and support the movement of the catheter within them.

[0041] Catheter structure

[0042] Each catheter can be constructed from a variety of materials, with various structures and / or layers within the catheter wall structure to impart specific properties or functional characteristics to the catheter. These may include:

[0043] Surface coatings – Surface coatings may ideally reduce thrombosis, have a low coefficient of friction, and / or antimicrobial properties.

[0044] Reinforcement – An internal wire braid is used to impart torque control / stiffness properties to the catheter.

[0045] Polymer layer - Different polymers can be used to impart different structural characteristics to the catheter body. For example,

[0046] Polyurethanes are soft and flexible, so they follow the guidewire more effectively. However, they have a higher coefficient of friction.

[0047] oNylon can be used to increase stiffness and be able to withstand higher flow rates of fluid passing through them.

[0048] The choice of a particular catheter or catheter system generally depends on the skill, experience, and preference of the particular physician prescribing active medical treatment.

[0049] Table 2 summarizes some typical characteristics of different catheters.

[0050] Table 2 - Summary of Catheter Characteristics

[0051]

[0052]

[0053] Typical endovascular procedures for ischemic stroke treatment

[0054] As mentioned above, when endovascular surgeons begin their procedures, they typically access the vasculature through the groin; however, as described below, other access areas, including the radial artery, are increasingly being used.

[0055] After groin puncture, different steps are performed to advance different catheters through the vasculature to the site of interest. Typically, in procedures using a balloon-guided catheter and a stent (i.e., a clot retrieval device), these steps include:

[0056] Step A—Aortic Arch Access

[0057] a) After groin puncture, a sheath is deployed. The sheath serves as a portal of entry and is typically inserted 15 cm into the femoral artery. The sheath ID is approximately 8 French. If the femoral and iliac arteries have significant tortuosity, a longer sheath (typically 45 cm long) may be used.

[0058] b) The assembly of the guiding catheter (GC) / balloon guiding catheter (BGC), diagnostic catheter (DC) and guidewire (GW) is advanced to the aortic arch.

[0059] The OD of the GC / BGC is typically 8F (matching the sheath). The DC (OD 4-6F) is retained within the BGC, and the GW (OD 0.035") is retained within the DC.

[0060] Step B—Carotid and Cerebral Artery Access

[0061] a) Maneuver the DC to access the desired carotid artery.

[0062] b) After entering the carotid artery, the GW is advanced, typically a maximum of 20-30 cm toward the occlusion site (but within the internal carotid artery).

[0063] c) After the GW is advanced (either simultaneously and / or sequentially), the DC is advanced over the GW to access the occlusion site. This can occur in a simultaneous and / or sequential process depending on the specific circumstances of the particular patient. However, there can be significant problems with this step. The DC is designed to be able to hook onto the relevant blood vessel. Typically, the tip (distal 5 cm) is pre-formed and the diagnostic catheter is generally rigid and torsionally reversible. These characteristics make it possible to hook onto the vessel, but then as the DC is advanced over the wire, it may hinder the physician who advocates for active treatment with medical measures. That is, the relative stiffness of the DC tip within the carotid artery may prevent it from sliding over the GW and causing the entire system to prolapse into the ascending aorta.

[0064] d) Another approach is to not advance the DC but instead advance the BGC while leaving the DC in situ at the vessel origin. This solution does sometimes work but often suffers from the same issues due to the stiffness of the guiding catheter.

[0065] Step C—Guiding Catheter (GC) / Balloon Guiding Catheter (BGC) Placement

[0066] a) The GC / BGC is advanced over the DC and GW to enter the carotid artery, usually the straight segment of the internal carotid artery.

[0067] b) Then remove DC and GW completely.

[0068] Step D—Microcatheter / Microwire Placement

[0069] a) A microcatheter (MC) and microwire (MW) are advanced together through the BGC until the clot is reached, such that the distal tips of the MC and MW are located at the distal edge of the clot.

[0070] b) After locating the MC, remove the MW.

[0071] Step E—Stent Deployment

[0072] a) The stent (ie, clot retrieval device) is advanced through the MC until the distal tip of the stent is adjacent to the distal end of the MC.

[0073] b) The stent is extracted by pulling back on the MC while holding the stent in place. As the stent is extracted, it expands toward the clot to engage with it.

[0074] Step F—Clot Removal

[0075] a) The BGC is inflated to stop forward flow and initiate reverse flow (suction) through the BGC.

[0076] b) Simultaneously, the stent, now engaged with the clot, is pulled proximally out of the body through the BGC along with the MC.

[0077] c) A check angiogram is performed by BGC to see if clot retrieval was successful. If not, steps E and F can be repeated.

[0078] d) Once reperfusion is successful, the BGC, stent, and clot are removed from the body.

[0079] change

[0080] During different procedures, a distal access catheter (DAC) (4-6.0 French) may be added to the procedure. This can be done in one of two ways:

[0081] A—Suction Technique

[0082] i. In this technique, after access to the internal carotid artery is achieved using a guiding catheter and DC, a guiding catheter (GC), which may or may not be a BGC, is placed in the internal carotid artery.

[0083] ii. Remove DC.

[0084] iii. A triaxial system consisting of a DAC, MC and MW is advanced toward the intracranial circulation with the goal of getting the tip of the DAC (aspiration catheter) to the surface of the clot. An integrated support catheter (ISC) as described in U.S. Patent 10,456,552 and incorporated herein by reference, can be used to improve / assist movement through these arterial systems. To achieve this, the MC and MW may have to be placed beyond the clot. Typically, the maximum size of the DAC in this case is 6 French. Larger sized catheters are not possible as they would require a larger guide catheter to support them in the neck and would not have sufficient distal flexibility to enable navigation / negotiation through tighter curves.

[0085] iv. Remove MW and MC (and / or ISC).

[0086] v. The DAC is located on the surface of the clot, and suction is applied through the DAC until the clot is successfully removed or the endovascular surgeon decides to try an alternative approach. The advantage of localized suction is the potential for delivering more suction pressure to the clot. However, as discussed below, there are several possible outcomes when suction is applied. Other disadvantages of the DAC are discussed below.

[0087] B—Solumbra Technology

[0088] i. The initial part of the technique is the same as the aspiration technique (ie, steps A(i)-A(iii)).

[0089] ii. However, once the MC is beyond the clot and the DAC is located on the clot surface, the MW is removed and the stent is deployed on the clot.

[0090] iii. Then, while suction is applied to the DAC, the MC and stent are retrieved. Therefore, the suction pressure is applied right next to the clot, rather than from the neck as with BGC. Furthermore, the stent is introduced into the DAC while still in the intracranial vessel, reducing the likelihood of losing the clot once captured.

[0091] If aspiration without a stent fails to successfully remove the clot, GW, MC, and stent can be subsequently deployed with the BGC in place.

[0092] In both techniques, the application of aspiration pressure has varying consequences. Generally speaking, a typical DAC (aspiration catheter) will be smaller than most clots, with the maximum ID of a DAC ranging from 0.053-0.068" (corresponding to an OD of 6 French), while the clot size / OD will be the same size as the ID of the vessel in which the clot is located (clots typically originate from more proximal sources, such as the heart or carotid artery; they will continue to migrate distally until the size of the embolus matches that of the vessel). Therefore, there will be a discrepancy between the size of the distal tip opening of the DAC and the size of the clot and / or vessel. Furthermore, most intracranial vessels are quite tortuous, and as the DAC is advanced, it will tend to rest on the outside of the curve. As a result, the distal tip of the DAC may not be perpendicular to the vessel wall and / or may partially separate from the vessel wall, allowing the clot to partially engage the outer edge of the DAC.

[0093] Furthermore, in cases where the clot is “significantly” larger than the DAC, aspiration through the distal tip of the DAC typically does not achieve ingestion of the clot, but rather the proximal portion of the clot becomes “stuck” at the distal tip of the DAC and cannot be pulled into the DAC during aspiration, as most clots are not very compressible.

[0094] Importantly, because the properties of the clot vary widely in terms of consistency / rigidity / internal cohesion, ultimately the application of suction and / or proximal pressure may result in:

[0095] a) The entire clot is taken up into the DAC (desirable).

[0096] b) Partial disruption of the clot into one or more smaller fragments, with the proximal fragment being completely ingested into the DAC, which may result in (undesirable) distal migration of the fragment.

[0097] c) The clot is not taken up into the DAC and blocks the distal end, thus requiring withdrawal of the DAC with only partial clot uptake (favorable end result, but likely not rapid).

[0098] d) As in c), a fibrin-rich region of the clot may become lodged in the DAC, requiring the DAC to be withdrawn to remove a portion of the clot. In some cases, the clot may also have less fibrin-rich regions, which may then break away from the lodgment site in the form of smaller fragments and migrate further distally (undesirable).

[0099] e) The clot is not fully engaged with the DAC and / or is not ingested, resulting in the clot being left in place (which may lead the surgeon to consider deploying a stent; less than ideal).

[0100] In general, of all these possibilities, complete clot ingestion is the most desirable because it a) prevents fragmentation, b) prevents distal embolization, and c) allows aspiration pressure to be transferred to the next portion of the clot as the more proximal portion of the clot is drawn into the catheter. However, as mentioned above, DACs generally have an upper size limit, thus potentially leading to a greater size mismatch between the vessel / clot and the DAC.

[0101] Additionally, once the clot is believed to have been captured, the DAC is usually completely removed from the body for a review angiogram. A review angiogram is performed to determine if the clot has been completely removed and to determine if any smaller fragments are left behind.

[0102] As previously mentioned, the BGC is used to enable the surgeon to stop antegrade blood flow, and it is necessary to minimize the risk of clot shearing and causing distal embolism when retrieving a DAC with a partially ingested clot. That is, because the diameter of the clot (and stent, if used) may be larger than the lumen of the BGC, when the DAC is withdrawn (with or without a stent), there is a significant chance that portions of the clot will be sheared off and cause distal embolism. Therefore, stopping antegrade blood flow by inflating the balloon can reduce the risk of this occurring. However, using a BGC reduces the size of the DAC, as it must reside within the BGC.

[0103] Thus, it is possible to advance a single large OD catheter (e.g., 7 French or larger) from the groin to the clot (e.g., at the M2 level or higher) to the extent that the larger distal opening can be used to fully engage the clot, thereby not merely capturing its proximal end at the tip under aspiration pressure, but rather completely ingesting it, which can greatly reduce the risk of distal embolization, the time to complete the aspiration procedure, and the cost of performing such a procedure. However, challenges include the ability to advance large OD catheters into cerebral arteries due to difficulties in maneuvering such devices through narrow curves and in the common procedures used in GC / BGC.

[0104] Furthermore, in the coronavirus era, hospital procedures have been altered to minimize risks to all health workers and patients, resulting in stricter isolation between personnel during preparation and performance of procedures. This isolation reduces the efficiency of medical procedures because moving equipment between designated areas requires more time. Consequently, there is now a greater incentive to design equipment, kits, and processes to overcome these inefficiencies arising from the coronavirus. Summary of the Invention

[0105] According to the present invention, systems and methods are provided for improving the efficiency and effectiveness of surgical procedures.

[0106] In a first aspect, the present invention provides a distal access point (DEP) for a brain aspiration (D2BA) catheter, the D2BA catheter being used to gain access to the carotid and cerebral arteries of a patient's brain during endovascular surgery and to aspirate one or more intracranial clots from the cerebral arteries, the D2BA catheter being placed within the patient's human vascular system between the DEP and the cerebral arteries within the brain, comprising: a soft distal tip region having a distal length sufficient to extend from a Class 1 or Class 2 arterial segment of the cerebral artery, or its equivalent, to the upper carotid vessel, the stiffness of the soft distal tip region being capable of movement through the Class 1 or Class 2 arterial segment of the cerebral artery, the outer diameter (OD) of which is 6F-10F; and a proximal region having a stiffness greater than that of the soft distal tip region, the length of the proximal region being sufficient to extend outside the patient's body through the DEP; wherein the D2BA catheter enables aspiration through the D2BA catheter to remove one or more clots.

[0107] In various embodiments:

[0108] The soft distal tip region and the proximal region have sufficient flexibility and axial and radial compressive stiffness to enable the soft distal tip region to be advanced over a guidewire (GW) and a diagnostic catheter (DC) to position the distal tip of the soft distal tip region in the upper neck / near skull base without an external support catheter.

[0109] The soft distal tip region and the proximal region have sufficient flexibility and axial and radial compressive stiffness so that when the soft distal tip region has been advanced over a guidewire (GW) and diagnostic catheter (DC) and positioned in the upper neck / near skull base, the guidewire and the diagnostic catheter can be withdrawn without causing the D2BA catheter to prolapse from the carotid artery.

[0110] The soft distal soft tip region and the proximal region have sufficient flexibility and axial and radial compressive stiffness so that when the GW and DC have been withdrawn, the microwire (MW) and integrated support catheter (ISC) can be advanced through the D2BA catheter to the distal tip and the D2BA catheter can be further advanced over the MW and ISC to a position where the distal tip substantially engages the cerebral artery wall near the clot.

[0111] The D2BA conduit has a wall thickness of 0.013 inches or less.

[0112] • The D2BA catheter has an outer diameter (OD) of 7 French and a distal length extending from the superior carotid vessels to the level 2 segment of the middle cerebral artery or from the distal cervical artery to the basilar artery or equivalent.

[0113] The distal end is 17-25 cm long.

[0114] The outer diameter (OD) of the D2BA catheter is 8F, and the distal length extends from the superior carotid vessels to the distal 1st stage of the middle cerebral artery.

[0115] The distal end has a length of 15-23 cm.

[0116] The outer diameter (OD) of the D2BA catheter is 9 French, and the distal length extends from the superior carotid vessels to the proximal 1st stage of the middle cerebral artery or equivalent.

[0117] The distal end has a length of 13-21 cm.

[0118] • The outer diameter (OD) of the D2BA catheter is 10F, and the distal length extends from the superior carotid vessel to the distal segment of the internal carotid artery or equivalent.

[0119] The distal end is 12-16 cm long.

[0120] • The soft distal tip region comprises at least one polymer portion configured to provide axial stiffness and flexibility for a specific linear position of the D2BA catheter.

[0121] • The proximal region comprises at least one polymer portion configured to provide axial stiffness and flexibility for a specific linear position of the D2BA catheter.

[0122] The D2BA catheter has torsional rigidity such that torque applied to the proximal region can be transmitted to the distal tip of the distal region, thereby enabling rotational movement of the distal tip within the blood vessel, and the distal tip defines an oblique angle within a range of 10-30 degrees with a vertical cross-section of the D2BA catheter.

[0123] In another aspect, the present invention provides an intravascular catheter system comprising: a D2BA catheter; and a second aspiration catheter having an outer diameter maximized for operative movement within the D2BA catheter and a length sufficient to extend to a position substantially equal to the distal tip of the D2BA catheter, the second aspiration catheter being configured to be positioned proximal to the distal tip of the D2BA catheter and capable of applying aspiration pressure to a proximal edge of a clot within the D2BA catheter via the second aspiration catheter. In one embodiment, the second aspiration catheter has a proximal end and a proximal lock that engages the proximal region of the D2BA catheter to prevent the second aspiration catheter from extending beyond the distal tip of the D2BA catheter.

[0124] In another aspect, the present invention provides an intravascular catheter system comprising: a D2BA catheter and a cooling catheter, wherein the outer diameter of the cooling catheter is maximized for operative movement within the D2BA catheter, and the length of the cooling catheter is sufficient to extend to a position substantially equal to the distal tip of the D2BA catheter, the cooling catheter being configured to deliver a cooling fluid through the cooling catheter to the distal tip of the D2BA catheter, and wherein the combination of the D2BA catheter and the cooling catheter provides sufficient thermal insulation to enable cooling fluid to effectively flow through the insulated catheter to effectively cool brain tissue after clot removal.

[0125] In various embodiments:

[0126] The outer diameter (OD) of the D2BA conduit is 8F, the outer diameter (OD) of the cooling conduit is substantially 6F, and the wall thickness of the cooling conduit is 0.020-0.03 inches, preferably 0.026 inches.

[0127] • The cooling conduit has a substantially uniform wall thickness along the length of the cooling conduit and includes thermal insulation to the distal tip of the cooling conduit.

[0128] On the other hand, the present invention provides an intravascular catheter system comprising: a D2BA catheter and a secondary D2BA catheter, wherein the outer diameter of the secondary D2BA catheter is maximized for operational movement within the D2BA catheter, and the length of the secondary D2BA catheter is sufficient to extend to a position beyond the distal tip of the D2BA catheter, and the secondary D2BA catheter is configured to enable the secondary D2BA catheter to be advanced to a position beyond the distal tip of the D2BA catheter and to apply suction pressure to the proximal edge of the secondary clot distal to the clot through the secondary D2BA catheter.

[0129] On the other hand, the present invention provides an intravascular catheter system comprising: a D2BA catheter; a diagnostic catheter (DC) and a guidewire (GW) for internally supporting the D2BA catheter for advancement toward the carotid artery; an integrated support catheter (ISC) having an outer diameter maximized for operational movement within the D2BA catheter, a length sufficient to extend beyond the distal tip of the D2BA catheter, and a distal taper for supporting the distal tip of the D2BA catheter during advancement of the D2BA catheter into the cerebral artery; a microwire (MW) configured for operational movement within the ISC and a length sufficient to extend beyond the distal tip of the ISC for advancement of the ISC and the D2BA catheter into the cerebral artery; a secondary D2BA catheter having an outer diameter maximized for operational movement within the ISC The secondary D2BA catheter is configured to be operatively moved within the secondary D2BA catheter and to be long enough to extend to a position beyond the distal tip of the D2BA catheter, the secondary D2BA catheter being configured to enable the secondary D2BA catheter to be advanced to a position beyond the distal tip of the D2BA catheter and to apply suction pressure to the proximal edge of the secondary clot away from the clot through the secondary D2BA catheter; a secondary integrated support catheter (ISC) having an outer diameter maximized to be operatively moved within the secondary D2BA catheter and to be long enough to extend to a position beyond the distal tip of the secondary D2BA catheter; and a secondary microwire (MW) configured to be operatively moved within the secondary ISC and to be long enough to extend to a position beyond the distal tip of the secondary ISC.

[0130] On the other hand, the present invention provides an intravascular catheter system comprising: a D2BA catheter; and a stent configured for operative movement within the D2BA catheter, the stent being operably connected to a push wire, the push wire being long enough to extend to a position beyond the distal tip of the D2BA catheter so that the stent can be deployed from the distal tip of the D2BA catheter.

[0131] On the other hand, the present invention provides a kit for obtaining access to the carotid arteries and cerebral arteries and aspirating intracranial clots from the cerebral arteries during intravascular surgery, comprising: an intravascular catheter for placement in the human vascular system between the distal access point (DEP) and the cerebral artery, and which contains the D2BA catheter; at least one diagnostic catheter (DC), the outer diameter of each DC being suitable for being mounted in the D2BA catheter and sliding in the D2BA catheter, and each DC having a pre-formed tip for accessing different anatomical structures of the aortic arch and having a longer length than the D2BA catheter; and a guidewire (GW) having a diameter suitable for being mounted in the DC and sliding in the DC, and having a longer length than the DC.

[0132] In various embodiments:

[0133] The kit further includes an internal support catheter (ISC) having an outer diameter suitable for fitting within and sliding within the D2BA catheter, and the ISC having a tapered distal region for supporting and steering the distal tip of the D2BA catheter in tightly curved arteries during advancement of the D2BA catheter into a cerebral artery.

[0134] • The kit has two or more DCs.

[0135] The kit includes an aspiration catheter having an outer diameter maximized for operative movement within the D2BA catheter and a length sufficient to extend to a position substantially equal to the distal tip of the D2BA catheter.

[0136] The kit includes a cooling catheter having an outer diameter maximized for operative movement within the D2BA catheter and a length sufficient to extend to a position substantially equal to the distal tip of the D2BA catheter.

[0137] The kit includes a second D2BA conduit sized to fit within the D2BA conduit, and a corresponding second ISC and second MW sized to fit within the second D2BA conduit, each having a length greater than the D2BA conduit.

[0138] In another aspect, the present invention provides a cooling catheter for delivering an effective volume of cooling fluid through a D2BA catheter, the cooling catheter having a catheter outer diameter maximized for operative movement within the D2BA catheter, the cooling catheter having a catheter length sufficient to extend to a position substantially equal to the distal tip of the D2BA catheter, the cooling catheter being configured to deliver cooling fluid through the cooling catheter to the distal tip of the D2BA catheter, and wherein the combination of the D2BA catheter and the cooling catheter provides sufficient thermal insulation to enable effective flow of cooling fluid through the insulated catheter to enable effective cooling of brain tissue following clot removal. In one embodiment, the cooling catheter has a substantially uniform wall thickness along the length of the cooling catheter and includes thermal insulation material to the distal tip of the cooling catheter.

[0139] In another aspect, the present invention provides an intravascular method for gaining access to a carotid artery and a cerebral artery, the intravascular method for placing a catheter system within the human vasculature between a distal access point (DEP) and a cerebral artery and aspirating a brain clot in one of the cerebral arteries, the method comprising the steps of:

[0140] a) Introducing the catheter system consisting of the D2BA catheter, guidewire (GW), and diagnostic catheter (DC) through DEP;

[0141] b) Advance the catheter system to the aortic arch;

[0142] c) Advance the GW and DC to the desired carotid artery and manipulate the GW to the desired carotid artery;

[0143] d) Advance the D2BA catheter to the desired carotid artery on the DC and GW;

[0144] e) Remove DC and GW;

[0145] f) introducing an internal support catheter (ISC) and an ISC microwire (ISC MW), the ISC having a tapered distal portion for supporting the distal tip of the D2BA catheter and adapted to facilitate movement of the distal tip through tight curves in the cerebral vasculature;

[0146] g) advancing the ISC and ISC MW into the clotted cerebral artery;

[0147] h) advancing the D2BA catheter to the proximal aspect of the clot and withdrawing the ISC and ISC MW; and,

[0148] i) Aspiration of the clot was performed through the D2BA catheter.

[0149] In another embodiment, the method further comprises the steps of:

[0150] j) After aspiration to remove the clot in step i, a review angiogram is performed to determine whether the entire clot has been removed and whether one or more distal emboli are present, and if so,

[0151] k) advancing a second D2BA catheter sized to coaxially move within the D2BA catheter along with a second ISC and a second ISC MW to the proximal end of the distal plug; and,

[0152] l) Applying suction to the second D2BA catheter to remove the distal embolism by suction or withdrawing the second D2BA catheter to remove the distal embolism.

[0153] In various embodiments:

[0154] The proximal end of the D2BA catheter is suitable for advancement from the radial artery puncture site.

[0155] The proximal end of the D2BA catheter is suitable for advancement from the femoral artery puncture site.

[0156] • Step i comprises applying one or more first pressure pulses through the D2BA catheter to help press the distal tip of the D2BA catheter against the clot, followed by applying at least one second suction pulse to aspirate the clot.

[0157] • The method comprises the steps of comparing a predetermined pressure pulse to a response pressure measured at the suction pump and adjusting subsequent pressure pulses based on the measured response pressure.

[0158] • The step of adjusting subsequent pressure pulses takes into account pressure response data from multiple patients collected and analyzed from similar procedures.

[0159] • Suction is applied via suction pumps and a central analysis computer system operatively connected to the internet, wherein pressure response data from the different pumps is received and analyzed by the central computer system, and wherein pump pressure algorithms are updated to the different pumps via the internet.

[0160] • The pump pressure algorithm takes into account catheter material, brand and / or size.

[0161] If aspiration is unsuccessful, introduce an aspiration catheter into the D2BA catheter, advance the aspiration catheter to the distal tip of the D2BA catheter, and perform aspiration through the D2BA catheter.

[0162] If the aspiration is successful, a cooling catheter is introduced into the D2BA catheter and advanced to the distal tip of the D2BA catheter, and a cooling fluid is flushed through the cooling catheter to achieve cooling of the brain tissue.

[0163] The method includes the step of flushing a brain nutrient solution through the cooling catheter.

[0164] The cooling catheter is an ISC with proximal insulation. After the ISC is removed and aspiration is completed, the ISC is reintroduced and brain nutrient solution is flushed through the ISC.

[0165] In another aspect, the present invention provides a method for effectively removing a heterogeneous clot having a fibrin-rich region and a red blood cell-rich region from a cerebral blood vessel, comprising the steps of:

[0166] a) Positioning the D2BA catheter near the proximal edge of the clot in a cerebral vessel;

[0167] b) applying a first pressure pulse to effect aspiration of a first proximal region of the clot; and

[0168] c) applying a second pressure pulse to effect aspiration of a second distal region of the clot.

[0169] In various embodiments:

[0170] • The first proximal region is a fibrin-rich region and the second distal region is a red blood cell-rich region.

[0171] • The method includes monitoring a first return pressure wave after transmitting the first pressure pulse and adjusting the second pressure pulse based on the first return pressure wave.

[0172] In another aspect, the present invention provides a cooling device for controlling the temperature of a cooling fluid delivered through a cooling conduit, comprising: a fluid cooling module for delivering the cooling fluid to a proximal end of the cooling conduit, the fluid cooling module having: a fluid pump and a controller for pumping a calculated volume of cooling fluid through the cooling conduit, the calculated volume being based on modeling of heat transfer through the cooling conduit, modeling data of a D2BA selected for a patient, patient data, and a desired cooling fluid temperature at the distal end of the cooling conduit.

[0173] On the other hand, the present invention provides a use of a D2BA catheter for accessing a cerebral artery without the support of a guide catheter and applying suction to one or more intracranial clots from the cerebral artery, the D2BA catheter being used to be placed in the human vascular system between a distal entry point (DEP) and a cerebral artery, comprising: a soft distal tip region having a distal length sufficient to extend from a Grade 1 or Grade 2 arterial segment or equivalent to an arterial vessel in the upper neck / near the skull base, the soft distal tip region having an outer diameter (OD) of 6F-10F; a proximal region connected to the soft distal tip region at a junction, the proximal region being long enough to extend outside the patient's body through the DEP and having an OD substantially similar to the soft distal tip region ID; and wherein the D2BA catheter is capable of achieving suction through the D2BA catheter to remove one or more clots.

[0174] In one embodiment, the soft distal tip region and the proximal region have sufficient flexibility and balanced axial and radial compressive stiffness relative to each other so that the soft distal tip region can be advanced over a guidewire (GW) and a diagnostic catheter (DC) to position the distal tip of the soft distal tip region in the upper neck / near the skull base without an external support catheter.

[0175] In another embodiment, the soft distal tip region and the proximal region have sufficient flexibility and balanced axial and radial compressive stiffness relative to each other so that when the soft distal tip region is located in the upper neck / near skull base position that has been advanced over a guidewire (GW) and diagnostic catheter (DC), withdrawal of the guidewire and diagnostic catheter will not cause the D2BA catheter to prolapse from the carotid artery.

[0176] In another embodiment, the soft distal tip region and the proximal region have sufficient flexibility and balanced axial and radial compressive stiffness relative to each other so that when the GW and DC have been withdrawn, the microwire (MW) and integrated support catheter (ISC) can be advanced through the D2BA catheter to the distal tip, and the D2BA catheter can be further advanced over the MW and ISC to a position where the distal tip substantially engages the wall of the cerebral artery adjacent to the clot.

[0177] In another aspect, the present invention provides an intravascular catheter for intravascular surgery, the intravascular catheter having a structure for obtaining access to the carotid artery and the cerebral artery and aspirating one or more intracranial blood clots from the cerebral artery, the intravascular catheter being used to be placed in the human vascular system between the distal entry point (DEP) and the cerebral artery, comprising: a soft distal tip region, the distal length of which is sufficient to extend from the first or second arterial segment of the cerebral artery or equivalent to the upper neck / near the skull base artery, the soft distal tip region having an outer diameter (OD) of 6F-10F, wherein the soft distal tip region is flexible to ride on a diagnostic catheter (DC) and a guidewire (GW) placed in the carotid artery, thereby entering the carotid artery through the aortic arch without causing prolapse of the DC and GW, and after removing the DC and GW, the D2BA catheter can be further advanced to the cerebral artery; a proximal region that transitions to the soft distal tip region, the proximal region having a length sufficient to extend outside the patient's body through the DEP; wherein the D2BA catheter can be advanced to the carotid artery without the support of a guide catheter.

[0178] In another aspect, the present invention provides a distal access point to brain aspiration (D2BA) catheter having an outer diameter greater than 6F and a length sufficient to extend from an extracorporeal distal access point (DEP) to a blood clot in a grade 1 or grade 2 cerebral artery, wherein the D2BA catheter has sufficient axial flexibility / stiffness along its length to enable the D2BA catheter to be advanced from the DEP over a guidewire (GW) and a diagnostic catheter (DC) to the distal tip of the GW and DC when the GW and DC are positioned at the upper cervical spine / near the skull base level, wherein the D2BA catheter can be advanced through the aortic arch supported solely by the GW and DC.

[0179] In another aspect, the present invention provides a distal entry point for a brain aspiration (D2BA) catheter, comprising a catheter having the following characteristics: an outer diameter of 6F-10F; a length sufficient to extend from a distal entry point (DEP) outside the body to a cerebral artery blood clot; a soft distal tip region having axial flexibility / rigidity along its length so that the D2BA catheter can be advanced from the DEP through a guidewire (GW) and a diagnostic catheter (DC) to the distal tip of the GW and DC when the GW and DC are located at the upper cervical spine / near the skull base level, the distal tip outer diameter of the soft distal tip region being selected to substantially match the inner diameter of the artery where the blood clot is located, and its length extending from the blood clot to the upper cervical spine / near the skull base level; a proximal region having axial flexibility / rigidity along its length to advance the D2BA catheter, and wherein the soft distal tip region can be advanced through the aortic arch supported only by the GW and DC.

[0180] In another aspect, the present invention provides an aspiration catheter (AC) having an outer diameter greater than 6F and a length sufficient to extend from a distal access point (DEP) to a Class 1 arterial segment or higher in the brain, wherein the AC has a distal region and a proximal region with combined axial flexibility and stiffness, capable of: advancing the AC over a diagnostic catheter (DC) and a guidewire (GW) located between the DEP and the carotid artery without prolapse of the DC and GW and without the need for support from a guide catheter (GC); withdrawing the DC and GW from the AC without prolapse of the AC; advancing the AC together with at least one microcatheter (MC) and microwire (MW) to a blood clot in a Class 1 or higher arterial segment; and, aspirating the blood clot through the AC.

[0181] In another aspect, the present invention provides an aspiration catheter (AC) comprising a catheter having the following characteristics: an outer diameter of 6F-10F and a length sufficient to extend from a distal entry point (DEP) to a blood clot in a cerebral artery, wherein the AC has a distal region having a distal tip with an outer diameter substantially corresponding to the inner diameter of the cerebral artery where the blood clot is located and having a length extending from the blood clot to the upper neck / near the skull base level, and wherein the distal region and the proximal region have a combined axial flexibility and stiffness such that: the AC can be advanced over a diagnostic catheter (DC) and a guidewire (GW) between the DEP and the carotid artery without prolapse of the DC and GW and without the need for support from a guide catheter (GC); the DC and GW can be withdrawn from the AC without prolapse of the AC; the AC can be advanced together with at least one microcatheter (MC) and microwire (MW) to the blood clot; and the blood clot can be aspirated by aspirating the AC so that the distal tip is in close proximity to the blood clot.

[0182] In another aspect, the present invention provides an integrated support and cooling catheter (ISCC) for assisting in advancing a D2BA catheter, such that after a clot is aspirated through the D2BA, the ISCC flows a cooling solution through the ISCC, the catheter of the ISCC having a tapered distal region for supporting the distal tip of the D2BA during advancement through a tortuous portion of the patient's cerebral vasculature, and an insulated proximal region for enabling a cooling solution to be introduced into the proximal end of the ISCC at 1-3°C, and wherein the cooling solution exits the ISCC at 2-8°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0183] The present invention is described with reference to the accompanying drawings, in which:

[0184] Figure 1A is a schematic diagram of a typical aortic arch and associated blood vessels according to the prior art.

[0185] Figure 1B Schematic diagram showing the sites of medium-vessel occlusion (MeVO) according to the prior art. These are generally defined as sites in the anterior circulation, including (A): the proximal M2 segment, distal M2 segment, M3 segment, A2 segment, and A3 segment. MeVO sites in the posterior circulation are generally defined as the P2 segment or P3 segment (B).

[0186] Figure 1C is a schematic diagram of clot Y located at the M1 segment in the MCA according to the prior art.

[0187] Figure 2A is a schematic diagram showing advancement of a guidewire, diagnostic catheter, and G2BA through the aortic arch and into the common carotid artery (CCA) according to one embodiment of the present invention.

[0188] Figure 2B is a schematic diagram showing the characteristics of the G2BA according to the present invention, including structural parameters of axial stiffness, radial compressibility, axial compressibility, and torsionalness.

[0189] Figure 3 is a schematic diagram of steps in a procedure for positioning a G2BA catheter within a patient's cerebral artery, according to one embodiment of the present invention.

[0190] Figure 3A Additional steps of a higher-level procedure are shown for positioning a G2BA catheter within a patient's cerebral artery according to one embodiment of the present invention.

[0191] Figure 4 is a schematic diagram showing the use of an integrated support catheter (ISC) to assist a G2BA catheter in traversing a tortuous portion of the cerebral vasculature according to one embodiment of the present invention.

[0192] Figure 4Ais a schematic diagram showing the use of two microcatheters as an integrated support catheter (ISC) to assist a G2BA catheter in traversing a tortuous portion of the cerebral vasculature according to one embodiment of the present invention.

[0193] Figure 5A is a schematic diagram showing potential engagement of an aspiration catheter and a clot according to the prior art.

[0194] Figure 5B is a schematic diagram showing potential engagement of an aspiration catheter and clot after suction has been applied according to the prior art.

[0195] Figure 5C is a schematic diagram of potential engagement of a G2BA catheter and clot after suction has been applied, according to one embodiment of the present invention.

[0196] Figure 5D is a schematic diagram showing a G2BA catheter with a twistable, angled tip.

[0197] Figure 6A Schematic diagram showing a clot stuck in a G2BA and an aspiration catheter near the distal tip of the G2BA.

[0198] Figure 6B Schematic diagram showing secondary aspiration of distal embolization using a G2BA catheter and a second G2BA catheter.

[0199] Figure 6C Schematic diagram of the insulation / cooling duct within the G2BA duct. DETAILED DESCRIPTION

[0200] Basic principles

[0201] The inventors appreciate that there are limitations to aspirating blood clots from cerebral arteries using existing catheter designs and methods.

[0202] the term

[0203] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. As used herein, unless otherwise expressly stated, the singular forms "a", "an" and "the" are intended to include the plural forms as well. It will be further understood that when used in this specification, the terms "comprises" and / or "comprising" specify the presence of the described features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items.

[0204] Spatially relative terms such as "distal," "proximal," "front," "rear," "under," "below," "lower," "over," "upper," and the like may be used herein to readily describe the relationship of one element or feature to another, as shown in the figures. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the features in the figures are inverted, elements described as "under" or "beneath" other elements or features would be oriented as "over" the other elements or features. Thus, the exemplary term "under" can include both above and below orientations. Features may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly. Similarly, unless expressly stated otherwise, the terms "upwardly," "downwardly," "vertical," "horizontal," and the like are used herein for purposes of explanation only.

[0205] It should be understood that when an element is referred to as being “on,” “attached,” “connected,” “coupled,” or “contacting,” etc., it can be directly on, attached, connected, coupled, or contacting the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly on,” “directly attached,” “directly connected,” “directly coupled,” or “directly contacting” another element, there are no intervening elements present.

[0206] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements, components, etc., these elements, components, etc. should not be limited by these terms. These terms are only used to distinguish one element, component, etc. from another element, component. Therefore, the "first" element or component discussed here may also be referred to as the "second" element or component without departing from the teachings of the present invention. In addition, unless otherwise expressly stated, the order of operations (or steps) is not limited to the order presented in the claims or drawings.

[0207] Structural parameters such as "axial stiffness," "radial compressibility," "axial compressibility," and "torqueability" can be described as being related to various functional properties of the catheter related to its performance or behavior in the human body during an endovascular procedure, as will be understood by those skilled in the art. That is, the catheters described herein are precision medical device components used in complex medical procedures that are more clearly and broadly defined in terms of their performance using various other devices (including the absence of various devices) as opposed to specific definitions using numerical ranges.

[0208] Except as otherwise described herein, or unless expressly provided otherwise, all numerical ranges, amounts, values and percentages, such as amounts of materials, contents of elements, times and temperatures, ratios of amounts and other contents, in the following portion of the specification and the appended claims, may be understood to begin with the word "about", even though the word "about" may not explicitly appear with the value, amount or range. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the appended claims are approximate values that may vary depending on the desired properties sought to be obtained according to the present invention. At the very least, and not attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted in light of the number of reported significant digits and by applying ordinary rounding techniques. Typically, the outer diameter of a catheter is expressed in French (FR) units, while the inner diameter (ID) of a catheter is expressed in inches. When referring to the size of a "sheath", French units are used to refer to the inner diameter.

[0209] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0210] Various aspects of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Furthermore, the drawings are not necessarily drawn to scale and are intended to emphasize principles of operation rather than precise dimensions.

[0211] introduce

[0212] Figure 1A A typical aortic arch 5 and associated vasculature are shown, including the ascending aorta 5a, descending aorta 5b, left subclavian artery 5c, common carotid artery 5d, brachiocephalic artery 5e, right subclavian artery 5f, and internal carotid artery 5g. Figure 1BSchematic diagram showing medium-sized vessel occlusion (MeVO) sites. These are typically defined as sites in the anterior circulation, including (A): the proximal M2 segment, distal M2 segment, M3 segment, A2 segment, and A3 segment. MeVO sites in the posterior circulation (B) are typically defined as the P2 or P3 segment. Figure 1C Schematic diagram of a clot lodged in the M1 segment of the MCA. The involved vessels include the common carotid artery (CCA), ophthalmic artery (OA), internal carotid artery (ICA), anterior cerebral artery (ACA), and middle cerebral artery (MCA), including the M1 and M2 segments.

[0213] According to the present invention, reference Figure 2A and Figure 3 , a large size aspiration (LSA) catheter 10 is described as having: 1) a distal region 10a having a distal end 10b that can be positioned near a typical clot within a specific region of the cerebral vasculature, including the Level 2 segments of the middle cerebral artery and the basilar artery (or higher) (collectively referred to as the "target level"), 2) a proximal region 10c having a proximal end 10d, wherein the LSA catheter does not require external support (e.g., by a guiding catheter (GC) or a balloon guiding catheter (BGC)) when passing through the aortic arch into the carotid artery, and 3) an outer diameter (OD) greater than 6F and less than or equal to 10F.

[0214] In the context of this specification, in various embodiments, the LSA catheter is referred to as the inguinal to brain aspiration catheter (G2BA), which refers to the most common access point (i.e., the groin) for performing endovascular surgery. However, the LSA catheter may also be referred to as the distal entry point (DEP) of the cerebral catheter (D2BA), which may include distal entry points of the femoral artery (groin) and the radial artery. That is, it is understood that other entry points for endovascular surgery other than the groin are also contemplated according to the present invention. Typically, as described below, the length dimension of the proximal region of the D2BA is adjusted based on the DEP, taking into account the respective distances from the inguinal entry point and the radial artery entry point. Therefore, references to the LSA, G2BA, and D2BA catheters are used in the description.

[0215] Generally, a G2BA catheter is defined as a catheter that can be used for endovascular procedures in the brain, having a larger OD (7-10F) and a correspondingly larger lumen (inner diameter) extending from a proximal end 10d to a distal end 10b, wherein the ID of the lumen is in the range of 0.066 inches to 0.105 inches (determined based on the intended target level, preferably 0.072 inches to 0.105 inches, and more preferably 0.078 inches to 0.105 inches).

[0216] In general, the outer diameter of the G2BA catheter at its distal end should closely match the lumen diameter of the target vessel, and the inner diameter of the G2BA should be as large as possible (ie, with minimal wall thickness) to provide the necessary rigidity for performing aspiration procedures as described herein.

[0217] Thus, at one level, the present invention seeks to enhance clot capture by aspiration by minimizing the difference in diameter between the clot and the G2BA catheter. In this regard, it is recognized that the ID of a G2BA catheter cannot be equal to the vessel lumen (due to catheter wall thickness), but clot capture can be significantly improved by minimizing this difference. Furthermore, it is also recognized that clots typically have a degree of compressibility, and that placing a catheter having substantially the same OD as the target vessel effectively wedges the catheter into the target vessel, which increases the aspiration pressure on the clot, as will be described in greater detail. It is also recognized that the larger G2BA lumen enables the application of higher aspiration forces without damaging the vessel lining.

[0218] Importantly, in the past, it was generally impossible to advance a larger sized aspiration catheter within the brain because the aspiration catheter required a larger guide catheter to be advanced into the neck to externally support the aspiration catheter as it was advanced. The use of an external guide catheter reduces the effective size of the aspiration catheter that can be advanced by the guide catheter. In addition, to date, aspiration catheters have not been able to be advanced on DC / GW due to the relative distal stiffness of such catheters. In addition, in the past, it was difficult to advance aspiration catheters through certain blood vessels (e.g., the ophthalmic artery) due to the tortuosity of the blood vessels and the relative distal tip stiffness of the aspiration catheter. Although U.S. Patent No. 10,456,552 teaches that the use of an internal support catheter (ISC) can improve the advancement of certain catheters through the tortuous portions of the cerebral vasculature, there are limitations considering the structure of the aspiration catheter.

[0219] As shown in Table 3, the G2BA is designed with different lengths and outer diameters (i.e., French sizes; referred to as "catheter sizes") to enable access to specific levels of the brain. These parameters are listed and discussed in Table 3.

[0220] Table 3 - G2BA characteristics and attributes

[0221]

[0222]

[0223] It is important to understand that the transition between the proximal and distal regions is preferably not abrupt and that the transition region may include multiple sub-regions that provide a transition between the properties of the proximal and distal regions. That is, the axial stiffness of the distal region may gradually increase in the proximal direction such that the physical properties of the G2BA have sub-regions that are consistent over the 4-8+ cm segment and then change to different sub-regions with different properties. For the proximal region, these Figure 3 Representatively shown are P1, P2, and P3 (where stiffness may increase from P1-P3) and D1, D2, and D3 (where stiffness may decrease from D1-D3). Thus, the transition point between the distal region and the proximal region is typically considered to be a measured distance from the distal tip (for a particular target level), where the transition point is the high carotid artery. In some embodiments, a specific radiopaque marker 40a can be incorporated into the transition point to help the physician visualize the location of the transition point and the location of the radiopaque distal tip marker 40.

[0224] Table 4 - Typical OD and ID Dimensions of Catheters

[0225] French Typical Wall Thickness (inches) Typical ID (inches) OD (inches) 7 0.009-0.013 0.066 0.092 8 0.009-0.013 0.079 0.105 9 0.009-0.013 0.092 0.118 10 0.009-0.013 0.105 0.131

[0226] The relative size of the G2BA catheter and the ability to deploy the G2BA to a level where the distal tip is substantially engaged with the vessel ID and proximal to the clot offer numerous advantages over past systems, particularly reduced entry time and the ability to capture the clot by aspiration.

[0227] The G2BA catheter eliminates the need for a GC or BGC by preventing (or substantially stopping) antegrade flow and the attendant risk of microembolic carryover during the procedure. That is, the effective size of the G2BA relative to the vessel ID substantially prevents antegrade flow due to gentle wedging of the distal tip within the target vessel after the G2BA catheter has been positioned.

[0228] G2BA structure

[0229] Catheters used to access brain regions are constructed using a variety of techniques to impart desired performance characteristics to the catheter, including pushability, torquability, trackability, and stiffness. Typically, catheters can be constructed from engineered polymers, including polyurethane, nylon, silicone rubber, polyethylene terephthalate (PET), latex, thermoplastic elastomers, and polyimides. Microfilaments of polymers and metals can also be incorporated.

[0230] Typically, catheters are assembled from smaller segments of polymers of varying formulations that are extruded, thermoformed, and / or thermoset using a wide range of techniques, including casting and / or assembly on a mandrel. Each formulation is carefully designed to have different properties; thus, different subregions can have slightly different stiffness properties along the length of, for example, the proximal or distal regions described above.

[0231] Deployment method and usage

[0232] According to the method of the present invention, reference Figure 2A 、 Figure 3 and Figure 3A A procedure for introducing a G2BA catheter (referred to as the "G2BA method") is described. For descriptive purposes, Figure 2A 、 Figure 3 and Figure 3A Assume access is from the femoral artery and into the M1 segment through the ICA. It should also be noted that Figure 3 and Figure 3A The length of each piece of equipment is not drawn to scale; specifically, for clarity, the external portion of each piece of equipment is not drawn to show a consistent overall length in each step listed below.

[0233] Initially, after arterial puncture, sheath 20 is deployed (step 1). The maximum ID of the femoral artery sheath is about 12F (usually 9-10F). Access through the radial or brachial artery will use a sheath with a maximum ID of about 7F-8F.

[0234] Thereafter or simultaneously, the assembly of the G2BA 10, a diagnostic catheter (DC) 24 with a tip 24a, and a guidewire (GW) 26 (typically 0.035 inches) is assembled and gradually introduced into the sheath (step 2) and advanced to the aortic arch. The G2BA, DC, and GW assembly will be selected based on the location of the clot and the physician's assessment of the aortic arch access vessels and the patient's aortic arch anatomy / variants. That is, when planning the procedure, the physician will determine the location of the clot and how to achieve access to the clot. In this example, if the clot is located at the M1 level, requiring access through the common carotid artery (CCA) and ICA, an 8F G2BA in combination with a preferred DC for accessing the CCA can be selected. Alternatively, if the clot is located at the P1 level of the fundus system, requiring access through the right subclavian, a smaller (e.g., 7F) G2BA and a different DC can be selected and assembled.

[0235] As the GW and DC are advanced to the aortic arch, the distal tip 10b of the G2BA will also be advanced and maintained thereafter, typically no more than 20 cm.

[0236] The DC and GW are manipulated to gain access to the desired carotid artery (step 2). During the step of obtaining carotid access, the GW is typically maintained in substantially the same position as the DC. In this step, the DC and GW are twisted, pushed and / or pulled so that the tip of the DC is hooked into the desired vessel. When the DC / GW is in the desired vessel, both can be advanced to the base of the skull by advancing the combination of the GW and DC (step 3). For example, in cases where there is severe tortuosity or stenosis or occlusion at the origin of the internal carotid artery (ICA), initial access to the external carotid artery (ECA) can be obtained. In some cases, a second "buddy wire", i.e., a second GW, can also be used to help the physician provide support for the system.

[0237] As the GW and DC remain roughly at the base of the skull, the G2BA is also advanced over the DC / GW, allowing the G2BA to follow the DC and GW until the distal tip of the G2BA is adjacent to the distal tips of the DC and GW (step 3). The soft distal tip and lack of a predetermined shape of the G2BA make it advantageous for following the DC and GW. At this point, the soft distal tip is completely within the carotid artery, while the more rigid proximal portion of the G2BA is within the carotid artery and approximately 10 cm (8-12 cm) beyond the aortic arch. The GW and DC typically do not extend beyond the base of the skull and are typically removed (step 4).

[0238] Importantly, with the removal of the stiffer portion of the G2BA in the carotid artery and the DC and GW (step 4), the risk of G2BA prolapse into the ascending aorta when additional devices are introduced into the G2BA is essentially eliminated (step 5).

[0239] In step 5, a microcatheter (MC) or integrated support catheter (ISC) 28 and a microwire (MW) 30 are introduced and advanced to the clot Y. When the MC or ISC and MW reach the clot, the G2BA 10 is advanced over the MC or ISC to the surface of the clot. For reasons explained below, it is preferred to use an ISC. Figure 4As shown, the ISC 28 features a distal taper 28a, a straight section 28b, and a proximal taper 28c (in various embodiments, the ISC may not have a proximal taper and the straight section 28b may extend along the entire proximal length of the ISC). This supports and otherwise provides an efficient transition between the catheter distal end 10b and the microcatheter, forming a smooth extension of the catheter distal end 10b. Specifically, the ISC fills the distal end of the G2BA catheter and provides a smooth extension for the catheter, particularly when the catheter assembly is moved through tight, tortuous regions of the vasculature 50. By extending and engaging the vessel wall 50, the vessel wall exerts a force F1 on the ISC, which is transmitted through the ISC, causing the ISC to exert a force F2 on the distal end 10b of the G2BA, thereby aligning the G2BA within the vessel 50 and enabling more efficient passage of the G2BA through the vessel. Thus, by selectively manipulating each of the G2BA, the ISC, and the MW, a physician can advance the G2BA through tortuous regions.

[0240] ISC is not needed because the physician may believe that the G2BA is unlikely to get stuck, but in most cases, it is better to introduce ISC rather than MC because of the anticipation that the G2BA may get stuck.

[0241] In addition, if Figure 4A As shown, an alternative could be for the physician to use two or more microcatheters (29a, 29b) to ease the G2BA around tight curves. In this case, each MC can be selectively advanced a short distance from the distal tip of the G2BA to provide alignment to prevent the G2BA from getting stuck.

[0242] The MC / ISC and MW are pushed forward to extend from the distal tip of the G2BA. The MC or ISC and MW and G2BA are gradually advanced to the clot by sequential manipulation of each.

[0243] It is important to note again that the G2BA has a larger OD and a relatively larger distal tip that is further advanced compared to previous aspiration catheters.

[0244] A larger diameter of the distal tip generally means that the G2BA will essentially occlude the vessel in which it is located, so due to the supporting pressure from the vessel wall, it is more likely that the distal tip of the G2BA will be aligned in a direction perpendicular to the vessel, as shown in Figure 2. Figure 5C As shown, compared with Figure 5A is slightly offset downward. Figure 5A As shown, according to the prior art, an AC that is smaller than a blood vessel may have unequal thrusts applied along the inner and outer edges of the catheter, such that there is a larger force F3 at the outer edge compared to the inner edge, one side of the distal tip ACt extends further through the blood vessel, and force F4 causes the distal tip to deflect to an angle θ. Figure 5AAs shown, if the distal tip ACt is not aligned, applying aspiration pressure P1 will result in a decrease in the effective pressure applied because blood may flow back into the catheter, as shown by P2 and P3.

[0245] Additionally, techniques to improve clot capture using smaller ACs involve drawing suction into the AC and waiting a period of time (typically 90 seconds) to allow the clot to potentially align with the AC and / or deform to engage the AC distal tip. Figure 5B As shown, application of aspiration pressure P1 may cause the clot Y to deform about AC, thereby preventing the clot from being aspirated and / or causing the clot to fragment.

[0246] like Figure 5C As shown, the distal tip of the G2BA is more likely to align with the clot, which in many cases will improve the likelihood of clot capture.

[0247] The G2BA has a larger distal tip opening, thus improving the likelihood of being perpendicular to the vessel and more likely to align and seal against the vessel wall. Therefore, the application of suction may be more effective because there may be less "leakage" around the distal tip.

[0248] Methods for preventing new territories of thrombus fragmentation / emboli

[0249] In other aspects, the present invention provides methods for reducing clot fragmentation and / or methods for reducing embolism in novel areas. As is known, a clot can be composed of distinct regions or segments with varying compositions that affect the overall stiffness / cohesion of the clot. Typically, the composition and consistency of a blood clot can vary between harder, fibrin-rich regions / segments and softer regions / segments, where the cohesion between these regions can be relatively strong or relatively weak. Fibrin-rich regions typically have greater cohesion, holding the clot together, while other regions may have lower cohesion and be more susceptible to fragmentation. When using smaller aspiration catheters and / or when the clot is fibrin-rich, it is common for the clot to become "plugged" at the end of the catheter and unable to be withdrawn by suction into the catheter. If the clot becomes plugged, the catheter must be withdrawn, which has two major potential disadvantages. First, the withdrawal action can result in loss of position, requiring time to regain position if necessary. Second, the withdrawal action can lead to clot fragmentation, where only portions / fragments of the clot are withdrawn, leaving behind portions / fragments of the clot at the clot site. Such clot fragments may be smaller and enter distal vessels, making retrieval more difficult. In addition, as the clot is withdrawn, it may encounter other large vessel origins. For example, as the catheter is withdrawn from the MCA, it may pass through the origin of the ACA: at this point, the clot may fragment, and part of the clot may enter the ACA, causing a new stroke, often called an infarct in new territory (INT).

[0250] If fragmentation occurs, the AC must be advanced back onto the clot surface after the first piece has been removed to remove one or more remaining fragments, which can significantly delay reperfusion.

[0251] Thus, G2BA also provides a method for reducing clot fragmentation by increasing the suction force applied to the clot at the intended level of G2BA, which is more likely to result in complete clot ingestion, thereby reducing the likelihood of requiring G2BA withdrawal which would result in fragmentation.

[0252] Similarly, a clot that is not completely aspirated or removed may fragment into one or more additional fragments / emboli that can propagate to distal sites. Therefore, G2BA also provides a method for reducing emboli in new territories by applying improved aspiration pressure to the clot, which increases the likelihood that any smaller fragments that would otherwise produce distal emboli will be aspirated along with the primary fragment of the clot.

[0253] Angled G2BA tip and twistable G2BA

[0254] Figure 5A It is shown that the tip of the AC may deflect as it is pushed around a curve such that the distal tip may have an angle θ relative to the vessel wall. Depending on the specific orientation of the distal tip and the specific proximal surface of the clot, this contact angle between the distal tip and the clot may aid aspiration or alternatively negatively impact aspiration. For example, if the distal tip forms an elliptical opening and the distal tip is oriented in such a way as to improve the contact angle with the clot, aspiration may be enhanced; however, similarly, if the angled surface is not "parallel" to the proximal surface of the clot, the contact angle between the distal tip and the clot may weaken aspiration. In general, an angled surface may increase the surface area in contact, further increasing the chance of clot ingestion. In the past, aspiration catheters were not designed to be twistable, and therefore the contact angle could not be controlled or varied.

[0255] Current catheters are not torquable because they are made of soft materials, and twisting (applying rotational force) on the portion of the catheter outside the body does not transmit the force to the distal end but can damage the catheter itself.

[0256] In one embodiment, the G2BA is constructed such that approximately 100-120+ cm of the proximal portion is twistable, so that only the distal 15-20+ cm of the softer distal portion transmits torque, resulting in a greater likelihood that the application of torque will successfully rotate the distal tip. Figure 5DA G2BA 10 is shown having a twistable distal portion with an angled distal tip 10b that can be twisted to improve the contact angle between the angled distal tip and the clot. Typically, in many cases, it is desirable to ensure that the outer distal tip is positioned outside the curve and / or positioned near the nearest edge of the clot. To enable visualization of distal tip placement, a radiopaque marker 40 is placed in the viewing tip.

[0257] In some cases, the physician may not be fully aware of the position of the distal tip relative to the vessel, and the rotational motion of the angled tip under aspiration pressure may result in the most favorable orientation of the tip in the vessel and cause abrupt ingestion of the clot.

[0258] Further distal surgery

[0259] In other embodiments, methods for enhancing the capture of embolic clots are described. In one example, after attempting to aspirate the clot with a G2BA, the clot may have become lodged at the distal tip. The physician may choose to withdraw the G2BA and hope that the clot does not fragment and / or cause distal embolization, either of which would require the G2BA to be lost if withdrawn. Figure 6A As shown, one solution provided by the G2BA is to run another aspiration catheter AC through the G2BA 10 to reach the distal tip of the G2BA and the embolized clot (while maintaining negative pressure / suction pressure through the smaller AC to secure the plugged clot). In a typical G2BA deployment, the G2BA is an 8F catheter, so approximately a 6F AC can be run up the G2BA. Preferably, the 6F catheter is designed so that the catheter cannot extend beyond the G2BA and therefore does not accidentally dislodge a clot that is plugged at the tip. Importantly, by placing the 6F AC in the Figure 6A On the embolic clot shown, a significantly greater suction force P5 can be applied by the 6F AC. The higher suction pressure at the center of the embolic clot can enhance the suction ability, even into a smaller catheter. Even if it cannot be aspirated into the smaller catheter, the additional suction force will keep it firmly held at the tip and when the 6F catheter is withdrawn, it will assist in the process of the entire clot being taken up by the larger catheter. Therefore, by applying this additional suction pressure and withdrawing the 6F AC, the embolic clot may be caused to slowly enter the 8F G2BA, and then it can be withdrawn in its entirety within the G2BA or the entire assembly can be withdrawn. In one embodiment, if the clot is aspirated in the G2BA, the AC can be advanced within the G2BA to apply suction pressure and potentially remove and / or assist in withdrawing the clot without losing its position.

[0260] In another embodiment, after aspiration of the clot, standard surgery is to perform a review angiogram to determine whether the entire clot has been removed. In some cases, fragments of the clot may have embolized and migrated distally, which would be detected by the review angiogram. In such cases, a secondary distal procedure may be performed.

[0261] For example, Figure 3A and Figure 6B As shown, if a review angiogram performed with the G2BA in place determines that a smaller embolus Y1 has dislodged and become lodged distally within the M3 segment while aspirating clot Y from the M1 segment through the 8F catheter 10, the physician may decide to perform an alternative secondary distal procedure, in which the following steps are followed:

[0262] a) While holding the first G2BA 10 in place, place the longer second G2BA 11 (with approximately 5 FOD) in conjunction with the second ISC (and second MW; Figure 3A The second G2BA 11 is sized to move coaxially within the first G2BA and is initially advanced to the distal tip of the first G2BA;

[0263] b) advancing the second MW and the second ISC beyond the distal tip of the first G2BA by selectively manipulating the second ISC, the second MW, and the second G2BA until they reach the proximal surface of the embolus Y1;

[0264] c) removing the second ISC and the second MW;

[0265] d) Applying suction force P6 to the second G2BA via the pump to draw the embolus into the second G2BA. If aspiration is unsuccessful but there is no blood reflux, the clot may have engaged with the distal tip but was not drawn into the second G2BA. In this case, the second G2BA (with the engaged clot fragment Y1) can be withdrawn into the first G2BA, and the second G2BA is withdrawn through the first G2BA.

[0266] e) perform angiography;

[0267] f) If clear, the first G2BA (and second G2BA, if still present) are removed.

[0268] g) If not clear, other options may be evaluated.

[0269] The G2BA can also be used in pediatric cases, in which case an appropriately smaller G2BA catheter will be used based on the patient's relative height / size.

[0270] Potential stenosis

[0271] In another application, it may be necessary to periodically stent an underlying stenosis while removing a clot. Stents may be required due to tight stenosis in the carotid artery or intracranial vessels. Because stents are relatively stiff, pushing these stents through all the curves and twists of the vascular system can be problematic. Additionally, if the outer diameter of the stent is larger than a conventional introducer sheath aspiration catheter, it must be withdrawn to allow for the larger system. Therefore, there may be advantages to using a G2BA in these procedures. In this case, a stent with a longer push wire is needed to enable it to pass through the G2BA. That is, current stents would require a longer push wire to enable them to be deployed through the longer G2BA catheter.

[0272] Radial artery access

[0273] As mentioned above, the DEP can be the radial artery. Accessing the carotid artery from the radial artery requires traversing the radial and brachial arteries to the aortic arch, which typically requires rotating the DC / GW 180 degrees to hook the desired carotid artery. Therefore, once deployed, the G2BA offers an advantage over previous AC / GC systems because the distal portion of the G2BA can more easily ride on the GW / DC and make the sharp turn at the aortic arch.

[0274] Cooling the brain

[0275] It is well known that cooling the brain has a neuroprotective effect when it is deprived of oxygen. In the case of stroke, cooling the brain before or after clot removal has been considered. Cooling the patient's entire body is often complicated because the effects of shivering often require general anesthesia and / or muscle relaxants. Consequently, attempts have been made to directly cool the brain by introducing a cooled fluid through a catheter after clot removal using the same catheter system. However, introducing a cooled fluid (typically cold saline) directly into the brain through a catheter has not been successful because the cooling fluid cannot be adequately isolated from the warm body at the point of introduction upon entering the brain. For example, a 6F catheter used as an aspiration catheter does not provide sufficient insulation to deliver a cooled fluid directly to the brain, and therefore requires further insulation if it is to be effective. However, a 6F catheter can only deliver a 4F catheter with a 2F lumen for delivering the cooled fluid. Given the length of a typical aspiration catheter, by the time the cooled fluid (for example, introduced at approximately 1°C) has traveled the length of the catheter, there is still insufficient insulation to produce an effective cooling effect. That is, upon exiting the catheter, the insufflated fluid may exit the catheter at a temperature of 15°C or higher, which is insufficient to provide effective cooling. Furthermore, this problem cannot be addressed by introducing a larger volume of fluid, as the volume of fluid that can be introduced is limited, and increased fluid volume can lead to other effects, including pulmonary edema.

[0276] Furthermore, adding insulation to the catheter wall changes its properties and makes it stiffer. Such insulated catheters, when advanced through a 6F catheter, are often unable to navigate the various curves required to reach cerebral vessels. Furthermore, because the insulation takes up space, the lumen is very small, making it difficult for the ISC to navigate curves more easily.

[0277] Attempts have been made to overcome stiffness issues by designing catheters with thinner, uninsulated distal 15 cm and insulated proximal portions. However, even with these designs, cooling efficiency is significantly reduced due to the heating of cold saline in the final 15 cm. However, when using a larger G2BA catheter within the brain, the volume available for insulation increases. Furthermore, because the cooling catheter has a larger volume within which to travel, insulation can be carried all the way to the tip of the cooling catheter, allowing flexibility to be incorporated into the distal portion and increased insulation. For example, after an 8F G2BA catheter is positioned in the M1 segment of the MCA and used to aspirate a clot, a 6F insulated catheter with a larger, more insulated wall is inserted into the G2BA and extended to the distal end of the G2BA. With better insulation, fluid introduced at 1–3°C may exit at 2–8°C, sufficient to effectively cool the brain.

[0278] The insulated conduit is essentially the same length as the G2BA conduit (nominally longer) and is sized to fit inside the G2BA. Figure 6C As schematically shown in Figure 1, an 8F G2BA 10 would have an OD of 0.105 inches and a typical wall thickness of 0.013 inches, allowing a 6F insulated catheter 13 to be routed therein. The insulated catheter has an OD of 0.079 inches and a wall thickness range of 0.026 inches, resulting in a lumen of 0.027 inches. The thicker wall provides additional insulation sufficient to deliver cool fluids to the distal tip of the G2BA and into the cerebral circulation. A 1.5F lumen size is the approximate minimum lumen size for delivering sufficient fluids.

[0279] In one embodiment, a fluid cooling module is configured to deliver cooling fluid to the proximal end of a cooling catheter. Typically, the fluid cooling module includes a fluid pump and a controller configured to pump a calculated volume of cooling fluid through the cooling catheter. The calculated volume is determined based on modeling of heat transfer through the cooling catheter, modeling data for a D2BA catheter selected for the patient, patient data, and a desired cooling fluid temperature at the distal end of the cooling catheter.

[0280] In one embodiment, the ISC also serves as a cooling catheter, referred to as an integrated support and cooling catheter (ISCC). In this case, the G2BA catheter is advanced using an ISCC with proximal thermal insulation. Once the ISCC is withdrawn and aspiration is performed, the ISCC is reintroduced and a flow of cooling solution is introduced. As with the ISC, the ISCC includes a tapered distal region to support the distal tip of the G2BA during advancement through the tortuous portions of the patient's cerebral vasculature, as well as an insulated proximal region that enables the introduction of cooling solution into the proximal end of the ISCC. From a performance perspective, cooling fluid introduced proximally at 1-3°C will exit the ISCC at 2-8°C.

[0281] Suction and suction pulses

[0282] Once the G2BA is in place, other procedures and devices can be employed to improve suction efficiency.

[0283] The application of suction pulses can also be used to improve G2BA engagement with the clot. Since a tighter seal with the vessel wall is likely to be higher, one or more short pressure pulses can cause the G2BA or clot to move closer to the other, resulting in more rapid engagement and / or ingestion, thus eliminating the need to wait for the catheter and clot to engage. For example, applying one to three short, low-pressure pulses followed by a larger pressure pulse can sequentially align or partially ingest a clot, followed by a higher pressure pulse for complete clot ingestion.

[0284] Furthermore, by comparing the applied pressure wave with the response measured at the pump, the effectiveness of the aspiration process can be quantified using measurements of the pressure wave at the pump. Response analysis can be used to dynamically adjust the delivery pressure. That is, the pump can generate a pressure wave, and measurements of the pressure / flow waveform received back from the G2BA can be compared to determine the effectiveness of the aspiration pressure in pressing the G2BA against the clot and / or aspirating the clot.

[0285] The pressure waves can also compensate for the compliance of the G2BA.

[0286] In another embodiment, the suction pump can be wifi enabled, thereby capturing suction pulse data and using that data to improve the pressure pulse through an algorithm based on machine learning and artificial intelligence, and using the information obtained from the first pressure pulse to improve the next pressure pulse based on the AI algorithm developed from a growing database of past performance.

[0287] Furthermore, the suction pressure on the suction pump may be higher given the increased diameter of the G2BA.

[0288] Preferably, the suction pump will include a filter that will capture any aspirated clots.Visual inspection of the clot at the suction pump, together with or alone the flow data obtained by the G2BA, can provide valuable information about whether blood circulation has been established and whether the procedure was successful.

[0289] The pulse pressure algorithm can also be applied to further distal procedures as described above.

[0290] G2BA Kit

[0291] Various kits can be provided as summarized in Table 5, where the kits are assembled based on target level (referred to herein as Levels 1-4, with Level 1 being deeper (eg, Level 2 segment) and Level 4 being lower in the vasculature).

[0292] Table 5 - G2BA / DC and ISC Kits

[0293] Target Level G2BA DC / MW ISC 1 FR 7 A FR 6 2 FR 8 A FR 7 3 FR 9 A FR 8 4 FR 10 A FR 9 1 FR 7 B FR 6 2 FR 8 B FR 7 3 FR 9 B FR 8 4 FR 10 B FR 9 1 FR 7 C FR 6 2 FR 8 C FR 7 3 FR 9 C FR 8 4 FR 10 C FR 9 1 FR 7 A, B, C FR 6 2 FR 8 A, B, C FR 7 3 FR 9 A, B, C FR 8 4 FR 10 A, B, C FR 9

[0294] Typically, surgeons select a kit based on the target level and knowledge of the vessel diameter at the site of the clot. Furthermore, a specific DC / GW combination may be selected based on the surgeon's diagnostic assessment of the patient's aortic arch. Table 5 references DCs for generic placeholders A, B, and C, each with specific tip / stiffness / shape characteristics.

[0295] Because of the cost difference between a DC and an ISC, a G2BA may be significant and a kit may include multiple DCs.

[0296] Additional kits are also described:

[0297] a) A kit containing a secondary G2BA, ISC, and MW of appropriate diameter for use with the kit shown in Table 5 or included in a kit for performing a secondary distal procedure.

[0298] b) The kit shown in Table 5, with an attached AC sized to fit the G2BA. The length of the AC prevents it from emerging from the distal tip of the G2BA.

[0299] c) Any of the above kits and cooling ducts.

[0300] Advantages Summary

[0301] The following advantages can be achieved by using G2BA and the G2BA deployment method, especially ISC.

[0302] a) Fewer catheters (importantly no GC or BGC).

[0303] b) Fewer steps and faster speed.

[0304] c) Larger catheters.

[0305] d) Ability to pass difficult sections.

[0306] e) Better tip alignment when applying suction.

[0307] f) The potential for introducing air bubbles into the circulation is reduced because fewer catheters are used that may not be adequately flushed.

[0308] g) Reduce the need for larger inguinal sheaths.

[0309] h) Reduced procedural costs, particularly by potentially eliminating the need for a stent retriever.

[0310] i) Improve reperfusion rate, thereby improving patient prognosis.

[0311] j) Reduce potential delays in operating theatres caused by the coronavirus by reducing the transfer of equipment between personnel.

[0312] k) Increase the speed of surgery using stiffer DCs by providing a softer G2BA distal region that can ride on stiffer DCs. This may encourage surgeons to select DCs that are more suitable for engaging the appropriate carotid origin.

[0313] l) Reduce the likelihood of clot fragmentation by complete ingestion of the clot.

[0314] m) Improved overall aspiration of non-heterogeneous clots. Some clots have varying consistencies and may split between regions of varying consistencies. By using an aspiration catheter that is sized close to the clot (and vessel), the likelihood of clot ingestion is much higher. This allows for more efficient ingestion of both fibrous and non-fibrous clots by enabling stronger pulse pressures and increasing the likelihood of sealing the entire clot.

[0315] n) Increase the speed of access to and removal of the secondary distal embolus using the secondary G2BA and ISC.

[0316] o) Reduce the possibility of causing secondary distal embolism.

[0317] p) Improve access from the radial artery.

[0318] q) Provides easier access to rigid stent systems in cases of severe intracranial or carotid atherosclerotic disease.

[0319] r) Provide easier access for insulated catheters to deliver cold solutions for local hypothermia in the ischemic area.

[0320] In summary, it is important to note that the structural and functional properties of D2BA catheters differ from those of other catheters. That is, while catheters capable of performing aspiration functions and available in a range of physical sizes and stiffnesses may appear similar, the differences in size, length, and combination of performance characteristics are significant because the combination of physical and functional properties enables new procedures to be performed with real benefits for patients. Furthermore, because a variety of manufacturing techniques and materials can be combined in different ways to provide catheters with unique combinations of physical and functional properties, it is important to understand how to balance the specific mechanical and chemical properties of the materials that may be used in catheter construction to provide the desired distal functional capabilities.

Claims

1. A catheter for obtaining access to the carotid and cerebral arteries in a patient's brain and for aspirating an intracranial clot from the cerebral arteries, comprising: A catheter body having a distal tip portion and a proximal portion, the catheter body having the following features: The length of the catheter body is greater than 120 cm; The length of the distal tip portion is 12-30 cm; The outer diameter is greater than 6F and less than 10F.

2. The catheter according to claim 1, wherein The distal tip portion has a stiffness that enables the distal tip portion to be advanced through the aortic arch without external support, riding over a guidewire and a diagnostic catheter that have been placed beyond the aortic arch. The catheter according to claim 2 , wherein the stiffness of the distal tip portion is less than the stiffness of the proximal portion.

4. The catheter according to claim 1, wherein The outer diameter is 7 French, and the length of the distal tip portion corresponds to the distance from the superior carotid vessels to the 2nd level segment of the middle cerebral artery, or the distance from the distal cervical artery to the basilar artery, or equivalent.

5. The catheter according to claim 4, wherein The length of the distal tip portion is 17-25 cm. The catheter according to claim 1 , wherein: The outer diameter is greater than 8 French, and the length of the distal tip portion corresponds to the distance from the superior carotid artery to the distal 1st stage segment of the middle cerebral artery.

7. The catheter according to claim 6, wherein The length of the distal tip portion is 15-23 cm.

8. The catheter according to claim 1, wherein The outer diameter is greater than 9 French, and the length of the distal tip portion corresponds to the distance from the superior carotid artery to the proximal 1st stage segment of the middle cerebral artery, or equivalent.

9. The catheter according to claim 8, wherein The length of the distal tip portion is 13-21 cm.

10. The catheter according to claim 1, wherein The outer diameter is 10F, and the length of the distal tip portion extends from the superior carotid vessel to the distal segment of the internal carotid artery, or equivalent.

11. The catheter according to claim 10, wherein The length of the distal tip portion is 12-16 cm.

12. The catheter according to claim 1, wherein The distal tip of the distal tip portion has a radiopaque marker.

13. The catheter according to claim 1, wherein The catheter body has a radiopaque marker at a transition point between the distal tip portion and the proximal portion.

14. The catheter according to claim 1, wherein The catheter body includes a transition region between the proximal portion and the distal tip portion, and the transition region includes sub-regions having different stiffness properties.

15. A distal access point for use in an endovascular procedure to gain access to a carotid artery and a cerebral artery in a patient's brain and to aspirate one or more intracranial clots from the cerebral artery, the cerebral aspiration catheter being configured to be advanced within the patient's body vasculature between the distal access point and the cerebral artery in the brain, comprising: a flexible distal tip region having a distal length sufficient to extend from a Class 1 or Class 2 arterial segment of the cerebral artery, or equivalent, to the upper carotid vessels, the flexible distal tip region having an outer diameter of 6 French to 10 French; and a proximal region having a stiffness greater than that of the flexible distal tip region, the proximal region being long enough to extend outside the patient's body through the distal entry point when the flexible distal tip region is within a cerebral artery; Wherein, after removal of the guidewire and diagnostic catheter, the brain aspiration catheter enables aspiration through the D2BA catheter to remove one or more clots.

16. A kit for obtaining access to the carotid and cerebral arteries and aspirating an intracranial clot from the cerebral arteries during endovascular surgery, comprising: An intravascular catheter for placement within the human vasculature between a distal access point and a cerebral artery, having a brain aspiration catheter having: A catheter body having a distal tip portion and a proximal portion, the catheter body having the following features: The length of the catheter body is greater than 120 cm; The length of the distal tip portion is 12-30 cm; The outer diameter is greater than 6F and less than 10F at least one diagnostic catheter, each having an outer diameter adapted to fit within and slide within the cerebral aspiration catheter, each having a pre-shaped tip for accessing a different anatomical structure of the aortic arch and having a longer length than the D2BA catheter; as well as The guide wire has a diameter suitable for being installed in the diagnostic catheter and sliding in the diagnostic catheter and has a length longer than the diagnostic catheter.

17. The kit according to claim 16 further includes an internal support catheter having an outer diameter suitable for being mounted within the brain aspiration catheter and sliding within the brain aspiration catheter, and the internal support catheter having a tapered distal region for supporting and steering the distal tip of the brain aspiration catheter in a tightly curved artery during advancement of the brain aspiration catheter into the cerebral artery.

18. The kit of claim 16, having two or more diagnostic catheters.

19. The kit of claim 16, further comprising an aspiration catheter having an outer diameter maximized for operative movement within the brain aspiration catheter and a length sufficient to extend to a position substantially equal to the distal tip of the brain aspiration catheter.

20. The kit of claim 16, further comprising a cooling catheter having an outer diameter maximized for operative movement within the brain aspiration catheter and a length sufficient to extend to a position substantially equal to the distal tip of the brain aspiration catheter.

21. The kit according to claim 16 further includes a second brain aspiration catheter, which is sized to be installed in the brain aspiration catheter, and a corresponding second internal support catheter and second microwire, which are sized to be installed in the second brain aspiration catheter, each of which is longer than the brain aspiration catheter.

22. The kit of claim 16, further comprising an integrated support and cooling conduit sized to fit within the D2BA conduit.

23. The kit of claim 22, wherein: The integrated support and cooling conduit comprises a length greater than the D2BA conduit.

24. The kit of claim 22, wherein: The integrated support and cooling conduit includes a tapered distal end region.

25. The kit of claim 22, wherein: In the cooling configuration, a cooling solution is delivered through the integrated support and cooling conduits.

26. The kit of claim 16, wherein: The D2BA catheter comprises a brain aspiration catheter.

27. Catheter system, comprising: suction catheter; an integrated support and cooling duct sized to fit within the suction duct, wherein the length of the integrated support and cooling conduit is greater than the length of the suction conduit; Wherein, in the cooling structure, the cooling solution is transported through the integrated bracket and the cooling conduit.

28. The catheter system of claim 27, wherein: The integrated support and cooling conduit includes a tapered distal end region.

29. The catheter system of claim 27, wherein: The suction catheter comprises: A catheter body having a distal tip portion and a proximal portion, the catheter body having the following features: The length of the catheter body is greater than 120 cm; The length of the distal tip portion is 12-30 cm; The outer diameter is greater than 6F and less than 10F.

30. The catheter system of claim 27, further comprising a diagnostic catheter sized to fit within the aspiration catheter and slide within the aspiration catheter.

31. The catheter system of claim 30, wherein: The diagnostic catheter includes a pre-shaped tip for accessing different anatomies of the aortic arch.

32. The catheter system of claim 30, wherein: The diagnostic catheter includes a length that is longer than a length of the aspiration catheter.

33. The catheter system of claim 30, further comprising a guidewire sized to fit within and slide within the diagnostic catheter.

34. The catheter system of claim 33, wherein: The length of the guide wire is greater than the length of the diagnostic catheter.

35. Catheter system, including: a first suction catheter; a second aspiration catheter sized to fit within and slide within the first aspiration catheter; Wherein, in the clot retrieval configuration, the first suction catheter applies a first suction pressure, the second suction catheter applies a second suction pressure, and the second suction force is greater than the first suction force.

36. The catheter system of claim 35, wherein: The length of the second suction conduit is shorter than the length of the first suction conduit.

37. The catheter system of claim 35, wherein: The first suction pressure and the second suction pressure are applied simultaneously.

38. The catheter system of claim 35, wherein: In the clot retrieval configuration, the distal end of the second aspiration catheter is inserted axially relative to the distal end of the first aspiration catheter.

39. The catheter system of claim 35, wherein: In the clot retrieval configuration, the first aspiration catheter and the second aspiration catheter are coaxial.

40. The catheter system of claim 35, wherein The length of the second suction conduit is greater than the length of the first suction conduit.

41. The catheter system of claim 40, further comprising a first integrated support catheter and a second integrated support catheter.

42. The catheter system of claim 41 further comprising a first microfilament and a second microfilament.

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