Periodic suction system using a vacuum pump and positive pressure pulse generator mechanism to generate a periodic suction pressure waveform

Abstract

A cyclic aspiration system generates a cyclic aspiration pressure waveform with intermittent, periodic intervals of vacuum pressure below atmospheric pressure and positive pressure above vacuum pressure. The system includes a flexible inlet tube connected in fluid communication between a vacuum pump and an aspiration catheter. A positive pressure pulse generator mechanism intermittently and periodically applies an external force that compresses a portion of the flexible inlet tube, reducing its internal volume and displacing collectable fluid therein, thereby generating positive pressure pulses. Upon removal of the applied external force, the flexible inlet tube is configured to be forcibly restored to its uncompressed state, increasing its internal volume while reducing the pressure therein until eventual regeneration of vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 447,506, filed February 22, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present disclosure relates generally to aspiration systems and methods for use during clot removal procedures for capturing and removing occlusions or clots. Specifically, the present disclosure relates to a cyclic aspiration system for capturing and removing occlusions or clots within a blood vessel, where the cyclic aspiration pressure waveform includes intermittent, periodic intervals of vacuum pressure (i.e., pressure below atmospheric pressure) and positive pressure (i.e., greater than vacuum pressure, and in some cases greater than atmospheric pressure). The cyclic aspiration system generates the cyclic aspiration waveform using a positive pressure pulse generator mechanism associated with a flexible inlet tube disposed in fluid communication between a vacuum pump and an aspiration catheter, where the positive pressure pulse generator mechanism generates positive pressure pulses (i.e., injections of positive pressure) by intermittently and periodically externally compressing a section along the flexible inlet tube to reduce volume and displace fluid collected therein, thereby generating positive pressure pulses. [Background technology]

[0003] Pulsatile or cyclic aspiration applies a cyclic pressure waveform with intermittent, periodic minimum / low / vacuum / aspiration pressure and maximum / peak / high pressure. During the minimum / low / vacuum / aspiration pressure cycles, the clot is drawn proximally and captured at the distal tip / end of the aspiration catheter, while during the maximum / peak / high pressure cycles, the clot is pushed distally. When utilizing pulsatile or cyclic aspiration during clot capture and removal, it is desirable to maximize the cyclic frequency of the cyclic pressure waveform, thus maximizing clot oscillation and thereby optimizing aspiration performance. One significant challenge in maximizing cyclic frequency is the specific response time required for the mechanical actuation of each active component, which limits the extent to which the cyclic frequency can be increased. Complex conventional systems for maximizing cyclic frequency have many active components, each of which must wait a response time before being activated to maintain normal operation. Therefore, in complex systems with many active components, the extent to which cyclic frequency can be maximized is undesirably reduced. Another concern is the tendency of conventional aspiration systems to become clogged by trapped clots. Summary of the Invention [Problem to be solved by the invention]

[0004] It would therefore be desirable to develop an improved cyclic suction system that utilizes as few active components as possible with the greatest associated response time to achieve maximum cyclic frequency, while also minimizing the damping or collapse of positive pressure waves and having the added benefit of reducing overall manufacturing costs. It would further be desirable to develop an improved cyclic suction system that prevents or minimizes the risk of clogging. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a pulsatile or cyclic suction system that uses as few active components as possible with associated maximum response times to achieve maximum cyclic frequency, generates a cyclic suction pressure waveform with intermittent periodic intervals of vacuum pressure below atmospheric pressure and positive pressure above vacuum pressure (higher than vacuum pressure, and in some cases higher than atmospheric pressure), and further has the added benefit of minimizing damping or decay of the positive pressure wave, reducing the overall cost of manufacture.

[0006] Another aspect of the present disclosure is directed to a cyclic aspiration system that generates a cyclic aspiration pressure waveform using a vacuum pump connected in fluid communication with the aspiration catheter via a flexible inlet tube, and a positive pressure pulse generator mechanism that applies an external force that compresses a portion of the flexible inlet tube, reducing the internal volume and displacing fluid collected therein, thereby generating positive pressure pulses (e.g., positive pressure infusions).

[0007] One aspect of the present disclosure is directed to a cyclic aspiration system that generates a cyclic aspiration pressure waveform of intermittent, periodic intervals of vacuum pressure (i.e., pressure below atmospheric pressure) and positive pressure (i.e., pressure above vacuum pressure, and in some cases above atmospheric pressure), wherein an inexpensive, flexible inlet tube that is contaminated by blood is disposable after a single use, while a more expensive component that applies an external force compressing the flexible inlet tube is not contaminated by blood and is therefore reusable.

[0008] Yet another aspect of the present disclosure is directed to a cyclic aspiration system that uses a vacuum pump and a positive pressure pulse generator to generate a cyclic aspiration pressure waveform by applying an external force that compresses a portion of a flexible inlet tube connected in fluid communication between the vacuum pump and the hub of the aspiration catheter, forcing the flexible inlet tube to return to its uncompressed state, maximizing achievable cyclic frequency while accelerating recovery time. [Brief explanation of the drawings]

[0009] The above and further aspects of the present disclosure will be further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in the various drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the present disclosure. The figures depict one or more implementations of the present device by way of example only, and not by way of limitation. [Figure 1A] 1 is an exemplary cyclic aspiration system according to the present disclosure, in which the positive pressure pulse generator mechanism is a displaceable plunger positioned externally along a portion of a flexible inlet tube (i.e., vacuum line) positioned between the vacuum pump and the hub of the aspiration catheter, the plunger being depicted in a retracted (i.e., removed) state, with the flexible inlet tube in an uncompressed state. [Figure 1B] 1B is an exemplary cyclic aspiration system of FIG. 1A, in which the plunger is depicted in an advanced (ie, extended) state (ie, compressed state) compressing the flexible inlet tube. [Figure 2A] 1 is another exemplary cyclical suction system according to the present disclosure, wherein the positive pressure pulse generator mechanism is a pressurizable bladder positioned externally along a portion of a flexible inlet tube (i.e., vacuum line) positioned between the vacuum pump and the hub of the suction catheter, the bladder being shown in an unpressurized state and the flexible inlet tube being depicted in an uncompressed state. [Figure 2B] FIG. 2A is an exemplary cyclic suction system in which the bladder is depicted in a pressurized state (i.e., compressed state) that radially contracts or compresses the inlet tube. [Figure 3A] 1 is yet another exemplary periodic suction system according to the present disclosure, wherein the positive pressure pulse generator mechanism is a displaceable plunger disposed externally along a portion of a flexible inlet tube (i.e., vacuum line) disposed between the vacuum pump and the hub of the suction catheter, the plunger including a recess for receiving the plunger therein while in an advanced state, the plunger being depicted in a retracted (i.e., removed) state with the flexible inlet tube in an uncompressed state. [Figure 3B]FIG. 3B illustrates an exemplary cyclic aspiration system in which the plunger is depicted in an advanced (ie, extended) state seated within the recess while compressing the inlet tube (ie, compressed state). [Figure 4A] 1 is yet another exemplary cyclical suction system according to the present disclosure, wherein the positive pressure pulse generator mechanism is a rotatable arm positioned externally along a portion of the inlet tube (i.e., vacuum line) disposed between the vacuum pump and the hub of the suction catheter, the rotatable arm being depicted in a retracted (i.e., removed) state with the flexible inlet tube in a non-compressed state. [Figure 4B] FIG. 4A is an exemplary cyclic aspiration system in which the rotatable arm is depicted in an advanced (i.e., extended) state compressing the inlet tube (i.e., compressed state) and displacing the volume within the tube toward the hub of the aspiration catheter. [Figure 5A] FIG. 1 is a perspective exploded view of an exemplary positive pressure pulse injection mechanism, the mechanism including a pair of electromagnets (a concave electromagnet and a planar base plate electromagnet) externally positioned along a portion of a flexible inlet tube (i.e., vacuum line) positioned between a vacuum pump and the hub of an aspiration catheter, the flexible inlet tube including a conductive strip embedded in the tube wall, and the base plate electromagnet further including a permanent magnet. [Figure 5B] FIG. 5B is a perspective view of the positive pressure pulse generator mechanism of FIG. 5A assembled along a portion of a flexible inlet tube. [Figure 5C] FIG. 5C is a perspective view of the positive pressure pulse generator mechanism of FIG. 5B, depicting the flexible inlet tube in an uncompressed state drawn against the concave contact surface of the first electromagnet when the first electromagnet is energized. [Figure 5D] FIG. 5C is a perspective view of the positive pressure pulse generator mechanism of FIG. 5B, depicting the flexible inlet tube in compression drawn against the planar contact surface of the second electromagnet when the second electromagnet is energized (“on”) and the first concave electromagnet is not energized (“off”). [Figure 5E]FIG. 5C is a perspective view of the positive pressure pulse generator mechanism of FIG. 5B showing how the compressed flexible inlet tube is held in place via a permanent magnet while simultaneously being attracted to the concave contact surface of an energized concave electromagnet, causing it to accelerate (i.e., forcibly) return to its uncompressed state. [Figure 6A] FIG. 1 is a perspective view of an exemplary extruded, cast, or molded flexible inlet tube having a non-circular radial cross-section that adds radial resistance features (e.g., fins) that prevent collapse under vacuum pressure, and gripping elements (e.g., rails) that accelerate (i.e., force) the recovery or return of the flexible inlet tube to its uncompressed state when the external force is removed. [Figure 6B] 6B depicts an exemplary positive pressure pulse generator mechanism for the extruded or cast flexible inlet tube of FIG. 6A as a displaceable compression plate and stationary base, each having a slot for slidably securing a respective gripping element (e.g., rail) of the extruded flexible inlet tube shown in an uncompressed state therein, thereby allowing unrestricted passage through the flexible inlet tube to the vacuum pump while preventing collapse of the flexible inlet tube under vacuum. [Figure 6C] The compression plate is shown in an advanced (e.g., extended) state (i.e., compressed state) compressing the extruded or molded flexible inlet tube, thus restricting passage to the vacuum pump and simultaneously displacing fluid collected within the flexible inlet tube toward the catheter hub, generating a positive pressure pulse, depicting the exemplary positive pressure pulse generator mechanism of FIG. 6B. [Figure 6D] FIG. 6B illustrates an exemplary positive pressure pulse generator mechanism depicting the accelerated (i.e., forced) recovery of the extruded flexible inlet tube to its restored (i.e., uncompressed) state during retraction of the compression plate, with the extruded flexible inlet tube secured to the compression plate, the radial resistance presented by the extruded flexible inlet tube once again allowing unrestricted access to the vacuum pump via the flexible inlet tube, and the radial force supplied to the flexible inlet tube (via the radial resistance elements (e.g., fins)) to prevent collapse while under vacuum. [Figure 7A]1 is yet another exemplary cyclic aspiration system according to the present disclosure, including a vacuum pump in fluid communication with a hub of an aspiration catheter via a flexible inlet tube, with a positive pressure pulse generator mechanism (e.g., a displaceable plunger) disposed along a portion of the flexible inlet tube and a separate, independently displaceable gate mechanism (e.g., a pinch valve) disposed proximally thereto (on the vacuum pump end of the tube), the displaceable gate mechanism being in a retracted (i.e., removed or open) state that allows unrestricted passage of vacuum pressure, and the plunger being depicted in the retracted (i.e., removed) state with the flexible inlet tube in a non-compressed state. [Figure 7B] FIG. 7B illustrates the exemplary cyclic aspiration system of FIG. 7A, with the displaceable gate mechanism in an advanced (i.e., extended) state restricting the passage of vacuum pressure, and the plunger partially or fully compressing (i.e., compressed) the flexible inlet tube to displace fluid collected therein toward the catheter hub, generating a positive pressure pulse and preventing fluid from being displaced by the displaceable gate mechanism into the vacuum pump. [Figure 8A] 7B is a modification of the cyclic suction system of FIG. 7A in which a positive pressure pulse generator mechanism (e.g., a displaceable plunger head) and a displaceable gate mechanism (e.g., a spring-loaded pin head) positioned proximally thereto (toward the vacuum pump) are integrated into a single mechanism that is simultaneously displaceable via a single actuator. The gate mechanism extends further toward the flexible inlet tube relative to that of the pulse generator mechanism to ensure initial compression of the flexible inlet tube by the gate mechanism. The displaceable plunger head is depicted in a retracted (i.e., removed) state in which the flexible inlet tube is uncompressed, and the spring-loaded pin head is in a retracted (i.e., removed) state that allows unrestricted passage of vacuum pressure. [Figure 8B]FIG. 8A illustrates an exemplary cyclic aspiration system in which the spring-loaded pin head is in an advanced (i.e., extended) state that restricts the passage of vacuum pressure, and the displaceable plunger head is depicted in an advanced (i.e., extended) state (i.e., compressed state) that partially or fully compresses the flexible inlet tube, thus displacing fluid in the line and generating a positive pressure pulse in the direction of the catheter hub while preventing fluid displacement by the pin head to the vacuum pump. [Figure 9] FIG. 10 depicts yet another exemplary cyclic aspiration system according to the present disclosure, including a vacuum pump in fluid communication with a hub of an aspiration catheter via a flexible inlet tube, wherein a positive pressure pulse generator mechanism (e.g., a reciprocating plunger) is disposed along a portion of the flexible inlet tube, proximal to which is disposed a separate, independently actuated reciprocating valve mechanism (e.g., a reciprocating pin), both of which are driven by cams having internal gears connected to a motor, the motor-driven cam contacting roller bearings that advance the mechanisms into the flexible inlet tube, the reciprocating pin in its advanced (i.e., extended) state restricting the passage of vacuum pressure, and the reciprocating plunger in its advanced (i.e., extended) state compressing the flexible inlet tube and displacing fluid therein, thereby generating a positive pressure pulse toward the catheter hub and preventing the pin from displacing fluid into the vacuum pump. [Figure 10A] 1 is a schematic diagram depicting an inlet tube fluidly connecting a proximal hub attached to an aspiration catheter with a pulsatile vacuum pump for generating a periodic aspiration pressure waveform including intermittent intervals of vacuum pressure (i.e., below atmospheric pressure) and positive pressure (i.e., above vacuum pressure, and in some cases above atmospheric pressure). In response to the periodic pressure waveform detected by the pressure sensor over time, adjustments are made to at least one parameter of the periodic aspiration pressure waveform associated with the pulsatile vacuum pump (e.g., vacuum pressure amplitude, positive pressure pulse amplitude, or cycle frequency) based on a determination of the percentage fibrin content of a clot captured at the distal tip of the aspiration catheter. [Figure 10B] 1 is a graphical representation of an exemplary substantially consistent, repeatable, or regular detected pressure waveform over time for a trapped, hard clot having a high fibrin content. [Figure 10C] 1 is a graphical representation of an exemplary substantially inconsistently repeatable or irregular detected pressure waveform over time for a trapped, fragile blood clot having low fibrin content. DETAILED DESCRIPTION OF THE INVENTION

[0010] As used herein, the term "about" or "approximately" in connection with any numerical value or numerical range indicates a suitable dimensional tolerance that enables a portion of a component or a collection of components to function for its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the recited value; for example, "about 90%" may refer to a range of values ​​of 71% to 99%.

[0011] As used herein, terms such as “component,” “module,” “system,” “server,” “processor,” and “memory” are intended to include one or more computer-related units, such as, but not limited to, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to, a processor, an object, an executable, a thread of execution, a program, and / or a process running on a computer. By way of example, both an application running on a computing device and the computing device may be a component. One or more components may reside within a process and / or thread of execution, and a component may be localized on one computer and / or distributed between two or more computers. Additionally, these components may execute from various computer-readable media having various data structures stored thereon. Components may communicate via local and / or remote processes, such as pursuant to a signal having one or more data packets, such as data from one component interacting with another component in a local system, a distributed system, and / or via a network, such as the Internet, with other systems via signals. The computer-readable medium may be non-transitory. The term "non-transitory computer-readable medium" includes, but is not limited to, random access memory (RAM), read-only memory (ROM), electronically erasable programmable ROM (EEPROM), flash memory or other memory technology, compact disc ROM (CD-ROM), digital versatile disk (DVD) or other optical storage device, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device, or any other tangible physical medium that can be used to store computer-readable instructions and / or data.

[0012] As used herein, the term "computing system" is intended to include a standalone machine or apparatus and / or combinations of machines, components, modules, systems, servers, processors, memories, detectors, user interfaces, computing device interfaces, network interfaces, hardware elements, software elements, firmware elements, and other computer-related units. By way of example and not limitation, a computing system may include one or more of a general-purpose computer, a special-purpose computer, a processor, a portable electronic device, a portable electronic medical device, a stationary or semi-stationary electronic medical device, or other electronic data processing device.

[0013] As used herein, the terms "tubular" and "tube" are intended to be broadly construed and are not limited to right cylindrical structures, or structures that are strictly circular in cross section, or structures that are uniform in cross section throughout their length. For example, a tubular structure or tubular system is generally depicted as a substantially right cylindrical structure. However, a tubular system can have a tapered or curved outer surface without departing from the scope of the present disclosure.

[0014] The documents incorporated by reference into this patent application should be considered an integral part of this application, provided that to the extent that any term is defined in these incorporated documents in a manner that contradicts the definition given herein, either expressly or implicitly, only the definition given herein should be considered.

[0015] The present disclosure relates to a periodic aspiration system for generating a periodic aspiration pressure waveform using a vacuum pump and a positive pressure pulse generator mechanism externally disposed along a portion of a flexible (i.e., compressible) inlet tube (i.e., vacuum line) connected in fluid communication between the vacuum pump and the proximal hub of an aspiration catheter. In accordance with the present disclosure, a periodic aspiration pressure waveform of intermittent, periodic intervals of vacuum pressure (i.e., below atmospheric pressure) and positive pressure (i.e., above vacuum pressure, and in some cases above atmospheric pressure) is generated via a positive pressure pulse generator mechanism that intermittently and periodically applies an external force that compresses the flexible inlet tube, reducing its volume and displacing collectable fluid therein, thereby generating positive pressure pulses (i.e., positive pressure injections) that counteract the vacuum pressure. Generation of a periodic aspiration pressure waveform using an internal solenoid is undesirable because it would be contaminated by aspirated blood. The positive pressure pulse generator mechanism according to the present disclosure is advantageously disposed externally to the flexible inlet tube (i.e., vacuum line), is not contaminated by blood, and is therefore reusable. On the other hand, flexible inlet tubes are inexpensive, do not become contaminated by blood, and are disposable after a single use, thereby preventing clogging.

[0016] When varying pressures (e.g., vacuum pressure and positive pressure pulses) to generate a cyclic aspiration pressure waveform, numerous factors must be considered when maximizing the oscillation or cyclic frequency. According to the present disclosure, positive pressure is injected or generated within a flexible inlet tube proximal to a vacuum pump. Another factor addressed by the presently disclosed positive pressure pulse generator mechanism is maximizing the oscillation or cyclic frequency when generating positive pressure pulses via compression of the flexible inlet tube (i.e., vacuum line). The recovery or restoration time for the flexible inlet tube to naturally (i.e., without force, assistance, or support) return to its uncompressed state after removal of an external compressive force is too slow, resulting in an unacceptably low cycling frequency. According to the present disclosure, a maximum cyclic frequency (preferably in the range of about 1 Hz to about 20 Hz) is achieved by forcing (i.e., accelerating) the return of the compressed flexible inlet tube to its uncompressed state (i.e., minimizing the recovery or restoration time) upon removal of the external compressive force.

[0017] Several non-limiting examples of cyclic aspiration systems are shown and described herein that generate cyclic aspiration pressure waveforms of intermittent, periodic intervals of vacuum pressure (i.e., pressure below atmospheric pressure) and positive pressure (i.e., pressure above vacuum pressure, and in some cases above atmospheric pressure) using a positive pressure pulse injection mechanism that applies an external force that compresses a portion of flexible inlet tubing that is in fluid communication between a vacuum pump and a hub attached to an aspiration catheter. In each example described herein, upon removal of the external compressive force, the return of the compressed flexible inlet tubing to its uncompressed state is forced, assisted, or accelerated in some way, thereby maximizing the cyclic frequency while minimizing recovery time.

[0018] 1A is a diagram of an exemplary cyclical suction system 100 according to the present disclosure in which a proximal hub 120 of a suction catheter 135 is fluidly connected to a vacuum pump 105 via a flexible (i.e., compressible) inlet tube 110 (i.e., vacuum inlet line). For example, the inlet tube 110 may be made of elastomer, silicone, rubber, or latex. Along a portion of the flexible inlet tube 110, distal to the vacuum pump 105, is a positive pressure pulse generator mechanism that applies an external compressive force, compressing or contracting the portion of the flexible inlet tube 110 to reduce its volume, thereby displacing any fluid collectable therein and generating a positive pressure pulse (i.e., positive pressure injection) that counteracts the vacuum pressure. In the example of FIG. 1A, the positive pressure pulse generator mechanism is a displaceable plunger 140 moved by a linear displacement mechanism 145 (e.g., a linear actuator, solenoid, reciprocating motor, cam, rotary motor, etc.) so as to be intermittently and cyclically displaceable between a non-deployed (i.e., retracted) state and a deployed (i.e., advanced or extended) state, as shown in FIGS. 1A and 1B, respectively. The plunger 140 and linear displacement mechanism 145 are disposed external to the flexible inlet tube 110. To maximize the switching of the cycle or oscillation frequency between vacuum and positive pressure, a radially self-expanding recovery structure 115 (e.g., a braid, scaffold, spring, or cage) is disposed within the lumen of the flexible inlet tube 110 coinciding with the portion compressed by the positive pressure pulse generator mechanism. The radially self-expanding recovery structure 115 may be any radially self-expanding mechanical structure that returns to its original, natural, or default (i.e., uncompressed) shape when the external compressive force is removed. Specifically, the radially self-expanding recovery structure 115 minimizes the recovery or recovery time for the compressed flexible inlet tube 110 to return to its uncompressed shape upon removal or release of the external compressive force (e.g., retraction of the plunger 140), as shown in Figure 1 A. Additionally, the radially self-expanding structure further resists or prevents collapse of the flexible inlet tube under vacuum.

[0019] During operation, as the aspiration catheter 135 is delivered through the vasculature to a target site proximal / facing the clot, the vacuum pump 105 generates vacuum pressure received within the aspiration catheter 135 via the flexible inlet tube 110. The linear displacement member 145 intermittently and cyclically displaces the plunger 140, compressing or contracting the flexible inlet tube 110 and reducing the volume of fluid collected therein, thereby generating positive pressure pulses (i.e., positive pressure injections) that counteract the vacuum pressure (FIG. 1B). Upon removal of the external force on the flexible inlet tube 110 (e.g., retraction of the plunger 140) (FIG. 1A), the radially self-expanding recovery structure 115 forces or accelerates the return of the flexible inlet tube 110 to its original (i.e., uncompressed) shape, thereby minimizing recovery time and maximizing cycle frequency. Additionally, the radially self-expanding recovery structure 115 further resists or prevents the flexible inlet tube 110 from collapsing under vacuum. Both the plunger 140 and the linear displacement member 145 are disposed externally of the flexible inlet tube 110 .

[0020] FIG. 2A illustrates another example of a positive pressure pulse mechanism according to the present disclosure as a pressurized bladder 240 filled with liquid and / or gas disposed along a portion of the flexible inlet tube 110. Instead of a motor, an auxiliary pump 250 oscillates to apply pressure (P) to the bladder 240, contracting or squeezing a portion of the flexible inlet tube 110. The applied pressure (P) transitions the bladder 240 from an unpressurized state (i.e., uncompressed flexible inlet tube 110) to a pressurized state (i.e., compressed flexible inlet tube 110), as depicted in FIGS. 2A and 2B, respectively (the inner wall of the flexible inlet tube 110 is shown in dashed lines). To maximize the cycle or oscillation frequency switching between vacuum and positive pressure, a radially self-expanding recovery structure 115 forces or assists the compressed flexible inlet tube 110 back to its uncompressed state when it is no longer constricted by the bladder 240 (i.e., minimizes recovery time). Additionally, the radially self-expanding recovery structure 115 further resists or prevents the flexible inlet tube 110 from collapsing under vacuum.

[0021] In operation, when the aspiration catheter 135 is delivered through the vasculature to a target site proximal / facing the clot, the vacuum pump 105 is activated to generate vacuum pressure received within the aspiration catheter 135 via the flexible inlet tube 110 while the bladder 240 is in an unpressurized state (i.e., uncompressed flexible inlet tube 110). In response to an externally applied force generated by the auxiliary pump (P) 250, the bladder 240 transitions to a pressurized state (i.e., compressed state) that contracts or squeezes the flexible inlet tube 110, reducing its volume and displacing fluid collected therein, thereby generating a positive pressure pulse (i.e., positive pressure infusion) that counteracts the vacuum pressure. In response to removal of the external force from the auxiliary pump (P) 250 on the bladder 240 (FIG. 2A), the radially self-expanding recovery structure 115 forces or accelerates the return of the flexible inlet tube 110 to its uncompressed shape or state, maximizing cycle frequency while minimizing recovery time (FIG. 2B). Additionally, the radially self-expanding recovery structure 115 further resists or prevents the flexible inlet tube 110 from collapsing under vacuum.

[0022] The previously described positive pressure pulse generator mechanism (FIGS. 1A-1B), which is disposed externally to the flexible inlet tube 110, poses a potential risk of clot entrapment at the pinch point (i.e., the tapered region of the flexible inlet tube 110 distal to the compressed portion). The modified positive pressure pulse generator mechanism of FIGS. 3A and 3B addresses this issue by configuring the plunger 140 within the flexible inlet tube 110 (i.e., the vacuum line). Referring to FIG. 3A, the profile of the flexible inlet tube 310 (i.e., the vacuum line) is modified to include a matching, mating, or complementary recess 312 to seat the plunger 140 therein. Thus, when displaced (i.e., advanced) by a linear displacement mechanism 145 (e.g., a linear actuator, a solenoid, a reciprocating motor, a cam, a rotary reciprocating mechanism, etc.), the plunger 140 seats within the recess 312, eliminating the pinch point and thereby preventing or minimizing potential clot entrapment. During operation, as the aspiration catheter 135 is delivered through the vasculature to a target site proximal / facing the clot, the vacuum pump 105 generates vacuum pressure received within the aspiration catheter 135 via the inlet tube 110. The linear displacement mechanism 145 intermittently and cyclically advances the plunger 140 to a position seated within the recess 312, compressing or contracting the flexible inlet tube 110, reducing its volume and displacing collected fluid therein, thereby generating a positive pressure pulse (i.e., positive pressure injection) that counteracts the vacuum pressure. Upon removal of the external force on the plunger 140 (FIG. 3A), the radially self-expanding recovery structure 115 forces or accelerates the return of the flexible inlet tube 110 to its original, natural, default (i.e., uncompressed) shape or state, maximizing cycling frequency while minimizing recovery time. Additionally, the radially self-expanding recovery structure 115 further resists or prevents the flexible inlet tube 110 from collapsing under vacuum.

[0023] 4A and 4B, the positive pressure pulse generator mechanism is a curved arm (e.g., cam arm) 440 electronically operated via a motor 455, the curved arm including a programmable controller (e.g., a processor or central processing unit (CPU)) and corresponding programmable memory device (e.g., RAM, ROM, EPROM, etc.) that stores instructions for intermittently controlling the frequency and / or degree or rotation of the arm 440 between a non-deployed (i.e., retracted) state ( FIG. 4A ) and a deployed (i.e., advanced or extended) state ( FIG. 4B ). In operation, as the aspiration catheter 135 is delivered through the vasculature to a target site proximal / face of a blood clot, the vacuum pump 105 generates vacuum pressure that is received within the aspiration catheter 135 via the flexible inlet tube 110. Motor 455 controls the rotation of arm 440, which intermittently and cyclically transitions between a retracted state ( FIG. 4A ) and an advanced (i.e., extended) state ( FIG. 4B ), compressing or contracting flexible inlet tube 110 and reducing and displacing the volume of fluid collected therein, thereby generating a positive pressure pulse (i.e., positive pressure injection). Upon removal of the compressive force on flexible inlet tube 110 (e.g., retraction of arm 440) ( FIG. 4A ), radially self-expanding recovery structure 115 forces or accelerates the return of flexible inlet tube 110 to its original, natural or default (i.e., uncompressed) shape or state, thereby maximizing cycling frequency while minimizing recovery time. Additionally, radially self-expanding recovery structure 115 further resists or prevents collapse of flexible inlet tube 110 under vacuum. Pressure sensor 113 is associated with flexible inlet tube 110 distal to a positive pressure pulse generator mechanism (e.g., rotatable arm 440) and controls, adjusts, or varies the amplitude of the positive pressure pulses generated by controlling (via a processor associated with motor 455) the degree of rotation of arm 440 and therefore the degree of compression of flexible inlet tube 110. Specifically, a maximum positive pressure pulse is generated when arm 440 is rotated to a maximum extended position (i.e., a fully forward position), resulting in maximum, full, or complete compression of flexible inlet tube 110, while only partial compression of flexible inlet tube 110 will generate a lower amplitude positive pressure pulse.Optionally, the distance separation between the centers of the arms 440 relative to the flexible inlet tube 110 can be varied using a linear displacement mechanism (e.g., a linear actuator) to adjust the amplitude of the generated positive pressure pulse. Raising the height of the arms 440 reduces or only partially compresses the flexible inlet tube 110, generating a lower amplitude positive pressure pulse, while lowering the height of the arms 440 compresses the flexible inlet tube 110 more, or even fully, generating a larger amplitude positive pressure pulse.

[0024] Yet another example of a positive pressure pulse generator mechanism according to the present disclosure utilizes multiple electromagnets disposed externally to the flexible inlet tube to intermittently and cyclically compress or contract the flexible inlet tube. In FIGS. 5A-5E, the flexible inlet tube 510 is electrically conductive. For example, the flexible inlet tube 510 may include multiple electrically conductive metal elements 513 (e.g., conductive metal wires or strips) associated therewith (e.g., disposed intraluminally, co-extruded, and / or embedded in its wall). The flexible inlet tube 510 preferably has four radially equidistantly spaced electrically conductive metal strips 513 extending axially or longitudinally. The first electromagnet 540 has a concave contact surface, and the second electromagnet 540′ has a planar (i.e., flat) contact surface, with the electrically conductive flexible inlet tube 510 disposed therebetween. Preferably, the concave contact surfaces of the first electromagnet 540 and the flexible inlet tube 510 are substantially equal in diameter.

[0025] During operation, the vacuum pump is activated as the aspiration catheter is delivered through a blood vessel to a target site proximal / facing the target clot. A periodic aspiration pressure waveform is generated by intermittently energizing the first electromagnet 540 or the second electromagnet 540' via the power supply 550. Specifically, the first electromagnet 540 is energized (i.e., switched "on") using the flexible inlet tube 110 (FIG. 5C) seated against the concave contact surface while the second electromagnet 540' remains de-energized (i.e., switched "off"), allowing unlimited or maximum passage of vacuum pressure therethrough to aspirate the clot at the distal tip of the aspiration catheter (i.e., vacuum pressure interval). Cycling the positive pressure interval is accomplished by de-energizing (i.e., switching “off”) the first electromagnet 540 and energizing (i.e., switching “on”) the second electromagnet 540′, which is attracted to its planar contact surface, thereby at least partially (and in some cases completely) collapsing, compressing, or flattening the flexible inlet tube 110 ( FIG. 5D ). In the example shown in FIG. 5D , the inlet tube 510 is depicted completely, fully, or completely folded or flattened onto itself. However, partial collapsing, compressing, or flattening of the flexible inlet tube 510 is possible by varying the energy level to the second electromagnet 540′ and thereby controlling the amplitude of the positive pressure pulse generated. As with the previous example, compressing the flexible inlet tube reduces its volume and displaces fluid collected therein, thereby generating a positive pressure pulse (i.e., positive pressure injection). This cycle repeats by energizing (i.e., switching "on") the first electromagnet 540 while de-energizing (i.e., switching "off") the second electromagnet 540' (FIG. 5E). When energized, the first electromagnet 540 draws the flexible inlet tube 110 thereto, engaging the concave contact surface and forcing or assisting the return of this "upper" portion to its uncompressed shape or state. At the same time, a forced or accelerated return of the "lower" portion of the flexible inlet tube 110 to its uncompressed shape or state is provided by a permanent magnet 560 extending axially or longitudinally along the second electromagnet 540', which holds the flexible inlet tube 110 in place.Alternatively, the permanent magnets may be replaced by mechanical features or components (e.g., rails, clips, clamps, or any other mechanical retention device, as in FIGS. 6A-6D) that hold or maintain the flexible inlet tube to the lower base plate. This forced or accelerated return of the respective "upper" and "lower" portions of the compressed flexible inlet tube 110 to their uncompressed state or shape minimizes recovery time while maximizing cycling frequency. Additionally, the magnets 540, 540, 560 further resist or prevent collapse of the flexible inlet tube 110 under vacuum.

[0026] Instead of magnets (FIGS. 5A-5E), the return of the compressed flexible inlet tube to its uncompressed state or shape may be forced or accelerated using mechanical components (e.g., gripping elements), thereby minimizing recovery time while maximizing cycling frequency. In the example depicted in FIGS. 6A-6C, the flexible inlet tube 610 is at least partially compressed, folded, contracted, or flattened between the displaceable compression plate 640 and the stationary base 640′. The gripping elements along the flexible inlet tube 610 are receivable within retention elements associated with each of the displaceable compression plate 640 and the stationary base 640′. 6A-6D, the flexible inlet tube 610 has axially or longitudinally extending rails 670, 670′ (e.g., T-shaped rails) slidable within slots 675′, 657′ defined in the displaceable compression plate 640 and the stationary base 640′, respectively, to secure the flexible inlet tube 610 in place therebetween. Securement of the flexible inlet tube 610 to the displaceable compression plate 640 and the stationary base 640′, respectively, forces or accelerates the return of the compressed flexible inlet tube 610 to its uncompressed state or shape during retraction of the compression plate 640 relative to the stationary base 640′, thereby maximizing cycling frequency while minimizing recovery time. To further assist in accelerating recovery time while maximizing cycling frequency, the flexible inlet tube 610 may preferably be extruded, cast, or molded into a non-circular shape with parallel tapered longitudinal sides (e.g., a “lip shape”) that provide radial resistance. Additionally, this shape resists lateral collapse of the flexible inlet tube 610 under vacuum when the compression plate 640 is retracted and the flexible inlet tube 610 is open to the vacuum pump. Although not required, the non-circular shape also facilitates the formation of a completion seal in the flexible inlet tube (i.e., the vacuum line) when pressed or squeezed between the compression elements (e.g., plunger 640 and base 640′) when full, maximum, or completion compression of the flexible inlet tube is desired. Prior to advancement of the compression plate 640 by the linear displacement member 680 (e.g., a solenoid, linear actuator, or reciprocating motor, cam, rotary reciprocating motor, etc.), the flexible inlet tube 610 is in an uncompressed shape or state, as shown in FIG. 6B, allowing unrestricted passage of vacuum pressure therethrough.On the other hand, FIG. 6C depicts compression plates 640 being advanced toward stationary base 640′ by linear displacement mechanism 680, at least partially compressing or contracting flexible inlet tubes 610 therebetween, reducing volume and displacing fluid collected therein, thereby generating a positive pressure pulse (i.e., positive pressure injection). Because flexible inlet tubes 610 are fixed thereto, during subsequent retraction of compression plates 640 relative to stationary base 640′, their return to an uncompressed state or shape is forced and assisted (rather than flexible inlet tubes 610 naturally recovering (i.e., unforced or unassisted)), thereby minimizing recovery or restoration time while maximizing cycling frequency ( FIG. 6D ). Additionally, the grip of flexible inlet tubes 610 to their respective compression plates 640 and stationary base 640′ further resists or prevents collapse while under vacuum.

[0027] 7A and 7B depict yet another embodiment of a positive pressure pulse mechanism disposed along a portion of the flexible inlet tube and a separate, independently displaceable gate mechanism disposed proximate thereto that acts as a valve controlling (i.e., restricting, but not necessarily cutting off) the passage therethrough of vacuum pressure generated by the vacuum pump 105. In this example, the positive pressure pulse mechanism includes a first linear displacement mechanism 788 (e.g., a linear actuator, solenoid, reciprocating motor, cam, rotary reciprocating motor, etc.) 788 for intermittently and cyclically advancing or retracting a plunger 740 connected thereto. While the plunger 740 is in an advanced state, the flexible inlet tube 110 (i.e., the vacuum line) is at least partially, though not necessarily completely or flawlessly, compressed, reducing its volume and displacing fluid collected therein, thereby generating a positive pressure pulse (i.e., positive pressure injection) that counteracts the vacuum pressure. Proximal to the plunger 790 is a separate displaceable gate mechanism (e.g., pin 790) that is independently displaceable via a second linear displacement mechanism 786 (e.g., a linear actuator, a solenoid, a reciprocating motor, a cam, a rotary reciprocating motor, etc.) that is controllable independently of the first linear displacement mechanism 788. The pin 790 functions as a valve (e.g., a pinch valve) that controls (e.g., limits, but does not necessarily close) the passage of vacuum pressure generated by the vacuum pump 105. Meanwhile, the first solenoid 788 controls the degree of compressive force applied to the flexible inlet tube 110 by varying the degree of advancement of the plunger 740. When advanced by the first linear displacement mechanism 788, the plunger 790 at least partially compresses, but does not necessarily flatten, the flexible inlet tube 110, reducing its volume and displacing fluid collected therein, thereby generating a positive pressure pulse (i.e., a positive pressure injection). As shown in the example of FIG. 7B, with the gate mechanism 786 in the fully closed position, the efficiency of the plunger 740 is maximized as the displaced fluid moves only distally toward the aspiration catheter without losses proximal to the vacuum pump.7A depicts a vacuum pressure interval of the periodic suction pressure waveform in which both the pin 790 and plunger 740 are retracted along with the uncompressed flexible inlet tube 110, allowing the unrestricted passage therethrough of the vacuum pressure generated by the vacuum pump 705. In FIG. 7B , on the other hand, the pin 790 is advanced by the second linear displacement mechanism 786, at least partially restricting, and in some cases completely blocking, the passage therethrough of the vacuum pressure generated by the vacuum pump 105. At the same time, the plunger 740, advanced independently by the first linear displacement mechanism 788, at least partially compresses, but does not necessarily completely flatten, the flexible inlet tube 110, reducing its volume and displacing fluid collected therein, thereby generating a positive pressure pulse (i.e., a positive pressure injection). Note that the pin 790, when advanced, does not necessarily occlude, block, or completely block the passage of vacuum pressure through the flexible inlet tube 110 (i.e., the vacuum line). It is contemplated that flexible inlet tube 110 (i.e., vacuum line) can remain partially open (e.g., pin 790 is in a partially advanced position) or fully open (e.g., pin 790 is in a fully retracted position) when the injected positive pressure is sufficient to counteract the vacuum pressure and provide a positive pressure pulse toward the clot. Controlling the degree of advancement of plunger 740 by first linear displacement mechanism 788, and therefore the degree of compression or retraction of flexible inlet tube 110, may be used to vary or adjust the amplitude of the positive pressure pulse generated.

[0028] The example of FIGS. 7A and 7B employs two independently controlled linear displacement mechanisms (e.g., solenoids 786, 788) to independently control / displace two separate components (e.g., pin 790, which acts as a valve controlling the passage therethrough of vacuum pressure generated by vacuum pump 705, and plunger 740, which compresses flexible inlet tube 110, reducing its volume and displacing fluid collected therein, thereby generating a positive pressure pulse (i.e., injected positive pressure). Rather than employing two separate components, each with its own associated linear displacement mechanism, FIGS. 8A and 8B are an alternative embodiment of a single linear displacement mechanism 888 (e.g., linear actuator, solenoid, reciprocating motor, cam, rotary reciprocating motor, etc.) that controls a single component having two heads, including a spring-loaded pin head 890, positioned axially proximal (i.e., toward the vacuum pump) of plunger head 840. When advanced, the spring-loaded pin head 890 controls the passage therethrough of vacuum pressure generated by the vacuum pump 805, and the plunger head 840 at least partially compresses, potentially flattening, and reducing the volume of the flexible inlet tube 110, displacing fluid collected therein, thereby generating a positive pressure pulse (i.e., positive pressure injection). Note again that the pin head 890, when advanced, does not necessarily occlude, block, or completely block the passage of vacuum pressure through the flexible inlet tube 110 (i.e., the vacuum line). With the pin head 890 in the fully closed position, the efficiency of the plunger head 840 is maximized, as displaced fluid travels only distally toward the aspiration catheter without loss proximal to the vacuum pump. The flexible inlet tube 110 (i.e., vacuum line) can be in a partially or fully open state (i.e., pin head 890 is in a partially advanced or fully retracted state) when the injected positive pressure is sufficient to counteract the vacuum pressure and provide a positive pressure pulse toward the clot. Controlling the degree of advancement of plunger head 840 by the single linear displacement mechanism 888, and therefore the degree of compression or retraction of inlet tube 110, may be used to vary or adjust the amplitude of the positive pressure pulse generated.

[0029] The illustrative cyclic aspiration system of FIG. 9 differs from the previous examples shown in FIGS. 7A and 7B in that two rotary reciprocating motors are employed to independently control the pin (displaceable gating device) and plunger (positive pressure pulse generator mechanism) instead of linear actuators. Referring to FIG. 9 , a reciprocating plunger 940 is cyclically actuated (i.e., advanced and retracted) by a first rotary-linear motion mechanism including, as an illustrative example, a cam 912, an internal drive gear 913 connected to the motor, and a roller bearing 914. The reciprocating plunger 940 is preferably spring-loaded 915 within a guide block 920 to provide axial resistance that restores the plunger 940 to a retracted state when not being advanced by the cam 912. The reciprocating plunger 940 is depicted in FIG. 9 in an advanced state, at least partially compressing and possibly flattening the flexible inlet tube 110 (i.e., vacuum line), reducing the volume for displacing fluid therein and thereby generating a positive pressure pulse (i.e., positive pressure injection) that counteracts the vacuum pressure. 7A, 7B, 8A, and 8B, a reciprocating plunger 940 is shown in FIG. 9 with a separate reciprocating pin 990 (which functions as a displaceable gating mechanism) independently actuable via an associated rotary-linear mechanism including, as an illustrative example, a gear 913, a cam 912, an inner drive gear 913 connected to a motor, and a roller bearing 914 similar to that of the reciprocating plunger 940. The reciprocating pin 990 functions as a valve that controls (i.e., at least limits, though not necessarily closes) the passage of vacuum pressure generated by the vacuum pump 105 (FIG. 9) through the reciprocating pin. Following the examples of FIGS. 8A and 8B above, it is further contemplated that a single rotary-linear mechanism including, as an illustrative example, a gear 913, a cam 912, an inner drive gear 913 connected to a motor, and a roller bearing 914 may control a single component having two reciprocating heads (i.e., the plunger head 940 and the proximally disposed pin head 990). The particular rotary-linear motion mechanism used may be modified as desired, and in the case of two separate rotary-linear motion mechanisms for controlling two separate components (e.g., a plunger and a pin), does not necessarily have to be identically configured for both.

[0030] As previously mentioned, the amplitude of the positive pressure pulse generated using any one of the above-described positive pressure pulse generator mechanisms may be varied or adjusted by varying the degree of compression of the flexible inlet tube (i.e., vacuum line) (e.g., the degree of plunger advancement). In this regard, such adjustment of the amplitude of the positive pressure pulse may be based on pressure detected or monitored by a pressure sensor associated with the flexible inlet tube (i.e., vacuum line) located proximal to the proximal hub of the aspiration catheter. Based on such detected pressure, the amplitude of the positive pressure pulse generated in the flexible inlet tube (i.e., vacuum line) using any one of the above-described exemplary positive pressure pulse mechanisms may be adjusted or controlled by varying the degree of compression of the flexible inlet tube (e.g., the degree of plunger advancement). In this regard, it is further recognized that the degree of seal formed by a clot captured at the distal tip / end of the aspiration catheter is indicative of the clot type (e.g., a hard clot is fibrin-predominant / rich, tough, and resistant to fragmentation, whereas a friable clot is red blood cell-predominant / rich, soft, and easily fragmented). By way of example, a hard clot, as measured histologically by area, has a red blood cell content ranging from about 0 to about 20%. Upon aspiration, a hard clot forms a tighter seal when captured at the distal tip / end of the aspiration catheter, resulting in a substantially consistent, repeating, or regular, cyclic pressure waveform measured at the distal tip / end, and thus at the proximal hub, and detected by the pressure sensor. Figure 10B is a graphical representation of a representative example of a substantially consistent, repeatable, cyclic pressure waveform indicative of a hard clot. In contrast to hard clots, friable clot fragments readily generate a more unstable, inconsistent, non-repetitive, and irregular cyclic aspiration pressure waveform due to the clot fragments entering the aspiration catheter and / or intermittently sealing at the distal tip / end. A representative example of an unstable, inconsistent, non-repetitive, and irregular cyclic aspiration pressure waveform indicative of a friable clot is shown in Figure 10C. Figure 10A is an exemplary aspiration catheter 1035 delivered through a blood vessel, depicting a clot captured at the distal tip / end.The inlet tube 1010 fluidly connects the proximal hub 1020 of the suction catheter 1035 to a pulsatile vacuum pump system 1005 to generate a periodic aspiration pressure waveform at intermittent, periodic intervals of vacuum pressure (i.e., below atmospheric pressure) and positive pressure (i.e., above vacuum pressure, and in some cases above atmospheric pressure). For example, the pulsatile vacuum pump system 1005 may be a vacuum pump and any one of the exemplary positive pressure pulse generator mechanisms shown herein and described above for generating the periodic aspiration pressure waveform by intermittently and periodically compressing a portion along the flexible inlet tube 1010. A pressure sensor 1030 is positioned proximal to the proximal hub 1020 for monitoring the periodic aspiration pressure waveform over time. Pressure data detected by the pressure sensor 1030 and / or via the user interface is accepted as input to the controller 1050 (e.g., a processor) for adjustment and optimization of one or more periodic aspiration pressure waveform parameters (e.g., amplitude of vacuum pressure (i.e., minimum pressure), amplitude of positive pressure pulses (i.e., peak pressure), and / or periodic frequency), which are associated with the pulsatile vacuum pump system 1005 based on the type of clot (e.g., hard vs. friable) as determined by the monitored periodic aspiration pressure waveform (e.g., substantially consistently repeatable or non-repeating) detected by the pressure sensor 1030.

[0031] Further aspects of the disclosure are provided by the following numbered clauses:

[0032] Clause 1 1. A periodic aspiration system for generating a periodic aspiration pressure waveform with intermittent, periodic intervals of a vacuum pressure below atmospheric pressure and a positive pressure above the vacuum pressure, the system comprising: a vacuum pump (105) for generating the vacuum pressure; a flexible inlet tube (110, 510, 610) having a proximal end and an opposite distal end, the proximal end of the flexible inlet tube (110, 510, 610) being fluidly connected to the vacuum pump (105); an aspiration catheter (135) having the flexible inlet tube (110, 510, 610), a distal tip, and a proximal hub (120) fluidly connected to the distal end of the flexible inlet tube (110, 510, 610); and a catheter (135) for intermittently and periodically applying an external force that compresses a portion of the flexible inlet tube (110, 510, 610) to reduce an internal volume within which fluid can be collected. and a positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) that displaces a fluid, thereby generating a positive pressure pulse, wherein the positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) is configured such that when an external force applied by the positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) is removed, the flexible inlet tube (110, 510, 610) is forcibly restored to an uncompressed state, increasing an internal volume while reducing pressure therein until an eventual regeneration of vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency.

[0033] Clause 2 The periodic suction system described in clause 1, wherein the positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) is positioned outside the flexible inlet tube (110, 510, 610), is not contaminated by blood, and is reusable, while the flexible inlet tube (110, 510, 610) is contaminated by blood and is disposable after a single use.

[0034] Clause 3 The periodic suction system of any one of clauses 1 to 2, wherein the positive pressure pulse generator mechanism is a displaceable plunger (140, 740, 840), a pressurizable bladder (240), a rotatable arm (440), a pair of electromagnets (540, 540'), or a compression plate (640).

[0035] Clause 4 A periodic suction system as described in any one of clauses 1 to 3, wherein the flexible inlet tube (110) is forced to restore to an uncompressed state via a radially self-expanding restoration structure (115) disposed therein that coincides with the portion compressed by the external force applied by the positive pressure pulse generator mechanism (140, 240, 440, 740, 840, 940), and the radially self-expanding restoration structure (115) further provides resistance to the collapse of the flexible inlet tube (110) while under vacuum pressure.

[0036] Clause 5 A periodic suction system as described in any one of clauses 1 to 4, wherein when the externally applied force is removed, the flexible inlet tube (110) is forced to return to its uncompressed state by being held in place via a retaining member while subjected to an external restoring force applied by a positive pressure pulse generator mechanism, and the retaining member resists collapse of the flexible inlet tube (110) while under vacuum pressure.

[0037] Clause 6 6. A periodic suction system as described in any one of clauses 1 to 5, wherein the flexible inlet tube (110) is electrically conductive, the positive pressure pulse generator mechanism comprises a first electromagnet (540) having a concave contact surface and a second electromagnet (540') having a flat contact surface, the flexible inlet tube (110) being disposed therebetween, and when the second electromagnet (540') is energized, the flexible inlet tube (110) is compressed while being attracted to the flat contact surface, and the retaining member is a permanent magnet (560) associated with the second electromagnet (540') that maintains the flexible inlet tube (110) in position while being attracted to the concave contact surface of the first electromagnet (540) when energized.

[0038] Clause 7 A cyclic suction system as described in any one of clauses 1 to 6, wherein the flexible inlet tube (110) is forcibly restored to its uncompressed state by being mechanically fixed between a stationary base (640') and a linearly displaceable member (640) that is movable relative to the stationary base.

[0039] Article 8 A cyclic suction system as described in any one of clauses 1 to 7, wherein the flexible inlet tube (610) is restored to its uncompressed state through the radial resistance presented by the flexible inlet tube (610) having an extruded, cast, or molded non-circular shape, which non-circular shape further provides resistance to the flexible inlet tube (610) collapsing while under vacuum pressure.

[0040] Article 9 A periodic suction system as described in any one of clauses 1 to 8, further comprising a displaceable gating device (740, 940) associated with the flexible inlet tube (110) arranged between the positive pressure pulse generator mechanism and the vacuum pump (105), the displaceable gating device (740, 940) controlling the passage of vacuum pressure generated by the vacuum pump (105), and the positive pressure pulse generator mechanism (740, 840, 940) and the displaceable gating device (790, 890, 990) being separate components independent of each other or being a single integrated component.

[0041] Article 10 A method of using a periodic suction system to generate a periodic suction pressure waveform with intermittent, periodic intervals of vacuum pressure below atmospheric pressure and positive pressure above vacuum pressure, the periodic suction system comprising a vacuum pump (105) for generating the vacuum pressure and a flexible inlet tube (110, 510, 610) having a proximal end and an opposite distal end, the proximal end of the flexible inlet tube (110, 510, 610) being connected in fluid communication with the vacuum pump (105). a suction catheter (135) having a flexible inlet tube (110, 510, 610) connected to the distal end of the flexible inlet tube (110, 510, 610), a distal tip, and a proximal hub (120) connected in fluid communication to the distal end of the flexible inlet tube (110, 510, 610); and intermittently and periodically applying an external force that compresses a portion of the flexible inlet tube (110, 510, 610) to reduce its internal volume while displacing fluid collectable therein, thereby generating a positive pressure pulse. a positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) configured such that when an external force applied by the positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) is removed, the flexible inlet tube (110, 510, 610) is forcibly restored to an uncompressed state, and an eventual regeneration of vacuum pressure and a positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) for increasing the internal volume while reducing the pressure therein, thereby minimizing recovery time and maximizing cycle frequency, the method comprising the steps of delivering an aspiration catheter (135) through a blood vessel to a target site proximal to the clot, and applying vacuum pressure generated by a vacuum pump (105); intermittently and periodically generating positive pressure pulses using a positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) by intermittently and periodically applying an external force that compresses a portion of the flexible inlet tube (110, 510, 610) to reduce an internal volume and displace fluid collected therein, thereby generating positive pressure pulses, wherein upon removal of the external force applied by the positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940), the flexible inlet tube (110, 510, 610) is forced to restore to an uncompressed state, increasing the internal volume while reducing the pressure therein, until an eventual regeneration of vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency.

[0042] Article 11 11. The method of claim 10, wherein the positive pressure pulse generator mechanism (140, 240, 440, 540, 540', 640, 640', 740, 840, 940) is positioned outside the flexible inlet tube (110, 510, 610), is not contaminated by blood, and is reusable, while the flexible inlet tube (110, 510, 610) is contaminated by blood and is disposable after a single use.

[0043] Article 12 12. The method of any one of clauses 10-11, wherein the positive pressure pulse generator mechanism is a displaceable plunger (140, 740, 840), a pressurizable bladder (240), a rotatable arm (440), a pair of electromagnets (540, 540'), or a compression plate (640).

[0044] Article 13 The method of any one of clauses 10 to 12, wherein the flexible inlet tube (110) is forced to recover to its uncompressed state via a radially self-expanding recovery structure (115) disposed therein that coincides with the portion compressed by the external force applied by the positive pressure pulse generator mechanism (140, 440, 740, 840, 940), and the radially self-expanding recovery structure (115) further provides resistance to the collapse of the flexible inlet tube (110) while under vacuum pressure.

[0045] Article 14 14. The method of any one of clauses 10 to 13, wherein the flexible inlet tube (110) is forced to return to its uncompressed state when the externally applied force is removed by being held in place via a retaining member while subjected to an external restoring force applied by a positive pressure pulse generator mechanism, the retaining member resisting collapse of the flexible inlet tube (110) while under vacuum pressure.

[0046] Article 15 15. The method of any one of clauses 10 to 14, wherein the flexible inlet tube (110) is electrically conductive, the positive pressure pulse generator mechanism comprises a first electromagnet (540) having a concave contact surface and a second electromagnet (540') having a flat contact surface, the flexible inlet tube (110) being positioned therebetween, and when the second electromagnet (540') is energized, the flexible inlet tube (110) is compressed while being attracted to the flat contact surface, and the retaining member is a permanent magnet (560) associated with the second electromagnet (540') that maintains the flexible inlet tube (110) in position while being attracted to the concave contact surface of the first electromagnet (540) when energized.

[0047] Article 16 16. The method of any one of clauses 10 to 15, wherein the flexible inlet tube (110) is forcibly restored to its uncompressed state by being mechanically fixable between a stationary base (640') and a linearly displaceable member (640) that is movable relative to the stationary base.

[0048] Article 17 17. The method of any one of clauses 10-16, wherein the flexible inlet tube (610) is restored to its uncompressed state via the radial resistance presented by the flexible inlet tube (610) having an extruded, cast, or molded non-circular shape, the non-circular shape further providing resistance to the flexible inlet tube (610) collapsing while under vacuum pressure.

[0049] Article 18 18. The method of any one of clauses 10 to 17, wherein the periodic suction system further comprises a displaceable gating device (740, 940) associated with the flexible inlet tube (110) disposed between the positive pressure pulse generator mechanism and the vacuum pump (105), the displaceable gating device (740, 940) controlling the passage of vacuum pressure generated by the vacuum pump (105), and the positive pressure pulse generator mechanism (740, 840, 940) and the displaceable gating device (790, 890, 990) are separate and distinct components independent of each other or are a single integrated component.

[0050] Article 19 A method for adjusting at least one parameter of a periodic suction pressure waveform generated by a pulsatile vacuum pump (1005) connected via an inlet tube (1010) to a proximal hub (1020) of an aspiration catheter (1035), the periodic suction pressure waveform being intermittent, periodic intervals of a vacuum pressure below atmospheric pressure and a positive pressure above the vacuum pressure, the method comprising the steps of delivering the aspiration catheter (1035) through a blood vessel to a target site proximal to a clot; and applying the periodic suction pressure waveform to capture the clot at a distal tip of the aspiration catheter (1035). 1035), detecting a pressure waveform over time based on pressure monitored in the system by at least one pressure sensor (1030), determining a characteristic of the captured clot based on the detected pressure waveform, and adjusting, using a controller (1050), at least one parameter of the cyclic suction pressure waveform based on the determined characteristic of the captured clot, the at least one parameter comprising: (i) an amplitude of the vacuum pressure, (ii) an amplitude of the positive pressure pulse, or (iii) a cyclic frequency.

[0051] Article 20 The method of clause 19, wherein the determined characteristic of the captured clot is a classification of the clot type as either (i) hard, if the detected pressure waveform is substantially consistently repeatable, or (ii) friable, if the detected pressure waveform is non-repeatable over time.

[0052] The descriptions contained herein are by way of example only and are not intended to limit the scope of the present invention in any way. As described herein, the present disclosure contemplates many variations and modifications of a periodic aspiration system for generating a periodic aspiration pressure waveform including intermittent, periodic intervals of vacuum pressure (i.e., below atmospheric pressure) and positive pressure (i.e., above vacuum pressure, and in some cases above atmospheric pressure) using a vacuum pump connected in fluid communication with the hub of the aspiration catheter and a positive pressure pulse generator that intermittently and periodically externally compresses a section along the flexible inlet tube to reduce its volume and displace fluid collected therein, thereby generating positive pressure pulses (i.e., positive pressure infusions). The positive pressure pulse generator mechanism according to the present disclosure is advantageously located externally to the flexible inlet tube (i.e., vacuum line), is not contaminated by blood, and is therefore reusable. The flexible inlet tube, on the other hand, is inexpensive, does not become contaminated by blood, and is disposable after a single use or procedure, thereby preventing clogging. Modifications and variations obvious to those skilled in the art in light of the teachings of the present disclosure are intended to be within the scope of the following claims.

[0053] [Embodiment] (1) A cyclic aspiration system for generating a cyclic aspiration pressure waveform with intermittent, periodic intervals of vacuum pressure below atmospheric pressure and positive pressure above vacuum pressure, said system comprising: a vacuum pump that generates the vacuum pressure; a flexible inlet tube having a proximal end and an opposite distal end, the proximal end of the flexible inlet tube being connected in fluid communication with the vacuum pump; an aspiration catheter having a distal tip and a proximal hub connected in fluid communication to the distal end of the flexible inlet tube; a positive pressure pulse generator mechanism that intermittently and periodically applies an external force that compresses a portion of the flexible inlet tube to reduce an internal volume and displace collectable fluid therein, thereby generating positive pressure pulses; wherein the positive pressure pulse generator mechanism is configured such that when the external force applied by the positive pressure pulse generator mechanism is removed, the flexible inlet tube is forced to return to an uncompressed state, increasing the internal volume while reducing the pressure therein until an eventual regeneration of the vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency. (2) A periodic suction system as described in embodiment 1, wherein the positive pressure pulse generator mechanism is located outside the flexible inlet tube, is not contaminated by blood, and is reusable, while the flexible inlet tube is contaminated by blood and is disposable after a single use. (3) The periodic suction system of embodiment 2, wherein the positive pressure pulse generator mechanism is a displaceable plunger, a pressurizable bladder, a rotatable arm, a pair of electromagnets, or a compression plate. (4) The periodic suction system of embodiment 1, wherein the flexible inlet tube is forced to restore to the uncompressed state via a radially self-expanding restoration structure disposed therein that coincides with the portion compressed by the external force applied by the positive pressure pulse generator mechanism, and the radially self-expanding restoration structure further provides resistance to collapse of the flexible inlet tube while under vacuum pressure. (5) The cyclic suction system of embodiment 1, wherein the flexible inlet tube is forced to return to the uncompressed state when the externally applied force is removed by being held in place via a retaining member while subjected to an external restoring force applied by the positive pressure pulse generator mechanism, and the retaining member resists collapse of the flexible inlet tube while under vacuum pressure.

[0054] (6) The periodic suction system of embodiment 5, wherein the flexible inlet tube is electrically conductive, the positive pressure pulse generator mechanism comprises a first electromagnet having a concave contact surface and a second electromagnet having a planar contact surface, the flexible inlet tube being disposed therebetween, and when the second electromagnet is energized, the flexible inlet tube is compressed while being attracted to the planar contact surface, and the retaining member is a permanent magnet associated with the second electromagnet that maintains the flexible inlet tube in position while being attracted to the concave contact surface of the first electromagnet when energized. (7) The cyclic suction system of embodiment 5, wherein the flexible inlet tube is forcibly restored to the uncompressed state by being mechanically fixable between a stationary base and a linearly displaceable member that is movable relative to the stationary base. (8) The cyclic suction system of embodiment 7, wherein the flexible inlet tube is restored to the uncompressed state through radial resistance presented by the flexible inlet tube having an extruded, cast, or molded non-circular shape, the non-circular shape further providing resistance to collapse of the flexible inlet tube while under vacuum pressure. (9) The periodic suction system of embodiment 1, further comprising a displaceable gating device associated with the flexible inlet tube disposed between the positive pressure pulse generator mechanism and the vacuum pump, the displaceable gating device controlling the passage of the vacuum pressure generated by the vacuum pump, and the positive pressure pulse generator mechanism and the displaceable gating device being separate and distinct components or being a single integrated component. (10) A method of using a periodic aspiration system to generate a periodic aspiration pressure waveform with intermittent, periodic intervals of a vacuum pressure below atmospheric pressure and a positive pressure above vacuum pressure, the periodic aspiration system including: a vacuum pump that generates the vacuum pressure; a flexible inlet tube having a proximal end and an opposite distal end, the proximal end of the flexible inlet tube being fluidly connected to the vacuum pump; a suction catheter having the flexible inlet tube, a distal tip, and a proximal hub fluidly connected to the distal end of the flexible inlet tube; and a catheter that connects a portion of the flexible inlet tube to the distal tip. a positive pressure pulse generator mechanism that intermittently and periodically applies a compressive external force to reduce an internal volume while displacing fluid collectable therein, thereby generating positive pressure pulses, wherein the flexible inlet tube is configured to be forcibly restored to an uncompressed state upon removal of the external force applied by the positive pressure pulse generator mechanism, increasing the internal volume while reducing pressure therein until eventual regeneration of the vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency, said method comprising: delivering the aspiration catheter through a blood vessel to a target site proximal to the clot; applying the vacuum pressure generated by the vacuum pump; intermittently and periodically generating positive pressure pulses using the positive pressure pulse generator mechanism by intermittently and periodically applying an external force that compresses the portion of the flexible inlet tube to reduce an internal volume and displace fluid collected therein, thereby generating the positive pressure pulses; wherein when the external force applied by the positive pressure pulse generator mechanism is removed, the flexible inlet tube is forced to restore to the uncompressed state, increasing the internal volume while reducing the pressure therein until an eventual regeneration of the vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency.

[0055] (11) The method of embodiment 10, wherein the positive pressure pulse generator mechanism is located outside the flexible inlet tube, is not contaminated by blood, and is reusable, while the flexible inlet tube is contaminated by blood and is disposable after a single use. (12) The method of embodiment 10, wherein the positive pressure pulse generator mechanism is a displaceable plunger, a pressurizable bladder, a rotatable arm, a pair of electromagnets, or a compression plate. (13) The method of embodiment 10, wherein the flexible inlet tube is forced to restore to the uncompressed state via a radially self-expanding restoration structure disposed therein that coincides with the portion compressed by the external force applied by the positive pressure pulse generator mechanism, the radially self-expanding restoration structure further providing resistance to collapse of the flexible inlet tube while under vacuum pressure. (14) The method of claim 10, wherein the flexible inlet tube is forced to return to the uncompressed state when the externally applied force is removed by being held in place via a retaining member while subjected to an external restoring force applied by the positive pressure pulse generator mechanism, the retaining member resisting collapse of the flexible inlet tube while under the vacuum pressure. (15) The method of embodiment 14, wherein the flexible inlet tube is electrically conductive, the positive pressure pulse generator mechanism comprises a first electromagnet having a concave contact surface and a second electromagnet having a planar contact surface, the flexible inlet tube being disposed therebetween, and when the second electromagnet is energized, the flexible inlet tube is compressed while being attracted to the planar contact surface, and the retaining member is a permanent magnet associated with the second electromagnet that maintains the flexible inlet tube in position while being attracted to the concave contact surface of the first electromagnet when energized.

[0056] (16) The method of claim 14, wherein the flexible inlet tube is forced to return to the uncompressed state by being mechanically fixable between a stationary base and a linearly displaceable member that is movable relative to the stationary base. 17. The method of claim 16, wherein the flexible inlet tube is restored to the uncompressed state via radial resistance exhibited by the flexible inlet tube having an extruded, cast, or molded non-circular shape, the non-circular shape further providing resistance to collapse of the flexible inlet tube while under vacuum pressure. (18) The method of claim 10, wherein the cyclic suction system further comprises a displaceable gating device associated with the flexible inlet tube disposed between the positive pressure pulse generator mechanism and the vacuum pump, the displaceable gating device controlling passage of the vacuum pressure generated by the vacuum pump, and the positive pressure pulse generator mechanism and the displaceable gating device being separate and distinct components or a single integrated component. (19) A method for adjusting at least one parameter of a periodic suction pressure waveform generated by a pulsatile vacuum pump connected via an inlet tube to a proximal hub of an aspiration catheter, said periodic suction pressure waveform being intermittent periodic intervals of a vacuum pressure below atmospheric pressure and a positive pressure above vacuum pressure, said method comprising: delivering the aspiration catheter through a blood vessel to a target site proximal to the clot; applying the periodic aspiration pressure waveform to capture the clot at the distal tip of the aspiration catheter; detecting a pressure waveform over time based on pressure monitored within the system by at least one pressure sensor; determining a characteristic of the trapped clot based on the detected pressure waveform; and using a controller to adjust at least one parameter of the periodic suction pressure waveform based on the determined characteristics of the captured blood clot, wherein the at least one parameter comprises (i) the amplitude of the vacuum pressure, (ii) the amplitude of the positive pressure pulse, or (iii) the periodic frequency. (20) The method of embodiment 19, wherein the determined characteristic of the captured clot is a classification of the clot type as either (i) hard, if the detected pressure waveform is substantially consistently repeatable, or (ii) friable, if the detected pressure waveform is non-repeatable over time.

Claims

1. 1. A cyclic aspiration system for generating a cyclic aspiration pressure waveform having intermittent, periodic intervals of vacuum pressure below atmospheric pressure and positive pressure above vacuum pressure, the system comprising: a vacuum pump that generates the vacuum pressure; a flexible inlet tube having a proximal end and an opposite distal end, the proximal end of the flexible inlet tube being connected in fluid communication with the vacuum pump; an aspiration catheter having a distal tip and a proximal hub connected in fluid communication to the distal end of the flexible inlet tube; a positive pressure pulse generator mechanism that intermittently and periodically applies an external force that compresses a portion of the flexible inlet tube to reduce an internal volume and displace collectable fluid therein, thereby generating positive pressure pulses; wherein the positive pressure pulse generator mechanism is configured such that when the external force applied by the positive pressure pulse generator mechanism is removed, the flexible inlet tube is forced to return to an uncompressed state, increasing the internal volume while reducing the pressure therein until an eventual regeneration of the vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency.

2. 2. The cyclic suction system of claim 1, wherein the positive pressure pulse generator mechanism is located outside the flexible inlet tube, is not contaminated by blood, and is reusable, while the flexible inlet tube is contaminated by blood and is disposable after a single use.

3. The cyclic suction system of claim 2 , wherein the positive pressure pulse generator mechanism is a displaceable plunger, a pressurizable bladder, a rotatable arm, a pair of electromagnets, or a compression plate.

4. 2. The cyclic suction system of claim 1, wherein the flexible inlet tube is forced to restore to the uncompressed state via a radially self-expanding restoration structure disposed therein that coincides with the portion compressed by the external force applied by the positive pressure pulse generator mechanism, the radially self-expanding restoration structure further providing resistance to collapse of the flexible inlet tube while under vacuum pressure.

5. 2. The cyclic suction system of claim 1, wherein the flexible inlet tube is forced to return to the uncompressed state when the externally applied force is removed by being held in place via a retaining member while subjected to an external restoring force applied by the positive pressure pulse generator mechanism, the retaining member resisting collapse of the flexible inlet tube while under the vacuum pressure.

6. 6. The periodic suction system of claim 5, wherein the flexible inlet tube is electrically conductive, the positive pressure pulse generator mechanism comprises a first electromagnet having a concave contact surface and a second electromagnet having a planar contact surface, the flexible inlet tube being disposed therebetween such that when the second electromagnet is energized, the flexible inlet tube is compressed while being attracted to the planar contact surface, and the retaining member is a permanent magnet associated with the second electromagnet that maintains the flexible inlet tube in place while being attracted to the concave contact surface of the first electromagnet when energized.

7. 6. The cyclic suction system of claim 5, wherein the flexible inlet tube is forced to return to the uncompressed state by being mechanically fixable between a stationary base and a linearly displaceable member that is movable relative to the stationary base.

8. 8. The cyclic suction system of claim 7, wherein the flexible inlet tube is restored to the uncompressed state through radial resistance presented by the flexible inlet tube having an extruded, cast, or molded non-circular shape, the non-circular shape further providing resistance to collapse of the flexible inlet tube while under vacuum pressure.

9. 2. The cyclic suction system of claim 1, further comprising a displaceable gating device associated with the flexible inlet tube disposed between the positive pressure pulse generator mechanism and the vacuum pump, the displaceable gating device controlling the passage of the vacuum pressure generated by the vacuum pump, the positive pressure pulse generator mechanism and the displaceable gating device being separate and distinct components or a single integrated component.

10. 1. A method of using a periodic aspiration system to generate a periodic aspiration pressure waveform with intermittent, periodic intervals of a vacuum pressure below atmospheric pressure and a positive pressure above vacuum pressure, the periodic aspiration system comprising: a vacuum pump that generates the vacuum pressure; a flexible inlet tube having a proximal end and an opposite distal end, the proximal end of the flexible inlet tube being fluidly connected to the vacuum pump; an aspiration catheter having the flexible inlet tube, a distal tip, and a proximal hub fluidly connected to the distal end of the flexible inlet tube; and a catheter that extends through a portion of the flexible inlet tube. a positive pressure pulse generator mechanism that intermittently and periodically applies a compressive external force to reduce an internal volume while displacing fluid collectable therein, thereby generating positive pressure pulses, wherein the flexible inlet tube is configured to be forcibly restored to an uncompressed state upon removal of the external force applied by the positive pressure pulse generator mechanism, increasing the internal volume while reducing pressure therein until eventual regeneration of the vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency, said method comprising: delivering the aspiration catheter through a blood vessel to a target site proximal to the clot; applying the vacuum pressure generated by the vacuum pump; intermittently and periodically generating positive pressure pulses using the positive pressure pulse generator mechanism by intermittently and periodically applying an external force that compresses the portion of the flexible inlet tube to reduce an internal volume and displace fluid collected therein, thereby generating the positive pressure pulses; wherein when the external force applied by the positive pressure pulse generator mechanism is removed, the flexible inlet tube is forced to restore to the uncompressed state, increasing the internal volume while reducing the pressure therein until an eventual regeneration of the vacuum pressure, thereby minimizing recovery time and maximizing cycle frequency.

11. 11. The method of claim 10, wherein the positive pressure pulse generator mechanism is located outside the flexible inlet tube, is not contaminated by blood, and is reusable, while the flexible inlet tube is contaminated by blood and is disposable after a single use.

12. 11. The method of claim 10, wherein the positive pressure pulse generator mechanism is a displaceable plunger, a pressurizable bladder, a rotatable arm, a pair of electromagnets, or a compression plate.

13. 11. The method of claim 10, wherein the flexible inlet tube is forced to recover to the uncompressed state via a radially self-expanding recovery structure disposed therein that coincides with the portion compressed by the external force applied by the positive pressure pulse generator mechanism, the radially self-expanding recovery structure further providing resistance to collapse of the flexible inlet tube while under vacuum pressure.

14. 11. The method of claim 10, wherein the flexible inlet tube is forced to return to the uncompressed state upon removal of the externally applied force by being held in place via a retaining member while subjected to an external restoring force applied by the positive pressure pulse generator mechanism, the retaining member resisting collapse of the flexible inlet tube while under the vacuum pressure.

15. 15. The method of claim 14, wherein the flexible inlet tube is electrically conductive, the positive pressure pulse generator mechanism comprises a first electromagnet having a concave contact surface and a second electromagnet having a planar contact surface, the flexible inlet tube being disposed therebetween such that when the second electromagnet is energized the flexible inlet tube is compressed while being attracted to the planar contact surface, and the retaining member is a permanent magnet associated with the second electromagnet that maintains the flexible inlet tube in place and is attracted to the concave contact surface of the first electromagnet when energized.

16. 15. The method of claim 14, wherein the flexible inlet tube is forced to return to the uncompressed state by being mechanically fixable between a stationary base and a linearly displaceable member that is movable relative to the stationary base.

17. 17. The method of claim 16, wherein the flexible inlet tube is restored to the uncompressed state via radial resistance exhibited by the flexible inlet tube having an extruded, cast, or molded non-circular shape, the non-circular shape further providing resistance to collapse of the flexible inlet tube while under the vacuum pressure.

18. 11. The method of claim 10, wherein the cyclical suction system further comprises a displaceable gating device associated with the flexible inlet tube disposed between the positive pressure pulse generator mechanism and the vacuum pump, the displaceable gating device controlling passage of the vacuum pressure generated by the vacuum pump, the positive pressure pulse generator mechanism and the displaceable gating device being separate and distinct components or a single integrated component.

19. 1. A method for adjusting at least one parameter of a periodic aspiration pressure waveform generated by a pulsatile vacuum pump connected via an inlet tube to a proximal hub of an aspiration catheter, the periodic aspiration pressure waveform being intermittent, periodic intervals of a vacuum pressure below atmospheric pressure and a positive pressure above vacuum pressure, the method comprising: delivering the aspiration catheter through a blood vessel to a target site proximal to the clot; applying the periodic aspiration pressure waveform to capture the clot at the distal tip of the aspiration catheter; detecting a pressure waveform over time based on pressure monitored within the system by at least one pressure sensor; determining a characteristic of the trapped clot based on the detected pressure waveform; and using a controller to adjust at least one parameter of the cyclic suction pressure waveform based on the determined characteristics of the captured blood clot, the at least one parameter comprising (i) the amplitude of the vacuum pressure, (ii) the amplitude of the positive pressure pulse, or (iii) a cyclic frequency.

20. 20. The method of claim 19, wherein the determined characteristic of the captured clot is a clot type classification: (i) firm, if the detected pressure waveform is substantially consistently repeatable, or (ii) friable, if the detected pressure waveform is non-repeatable over time.

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