Mechanically-operated resonant pulse relief valve to assist with suction removal of obstructions

Abstract

The manifold comprises an aspiration outlet configured to be fluidly coupled to a suction source, an aspiration inlet configured to be fluidly coupled to the aspiration catheter such that an aspiration flow path is formed between the aspiration catheter and the aspiration source, and a relief inlet configured to be fluidly coupled to a pressurized fluid source. The manifold further comprises a passive pressure oscillation assembly fluidly coupled between the relief inlet and the aspiration flow path. The passive pressure oscillation assembly is configured to operate between a normal mode that blocks fluid communication between the pressurized fluid source and the aspiration flow path and an oscillation mode that pulses fluid communication between the pressurized fluid source and the aspiration flow path.

Description

[Technical field]

[0001] The present disclosure relates generally to medical devices and intravascular medical procedures, and more particularly to devices and methods for aspirating objects from an anatomical structure, such as, for example, a blood clot from a patient's vasculature. [Background technology]

[0002] It is often desirable to remove tissue from the body as minimally invasively as possible to avoid damaging other tissue For example, removing tissue such as a blood clot from within the vasculature can improve a patient's condition and quality of life.

[0003] Many vascular problems are due to insufficient blood flow through blood vessels. One cause of insufficient or irregular blood flow is an obstruction within a blood vessel called a blood clot or thrombus. A blood clot or thrombus can embolize the patient's vasculature and form an embolus within the patient's vasculature. A blood clot can develop for many reasons, including damage to the arterial wall due to atherosclerotic disease, trauma resulting from surgery, or other causes.

[0004] When a thrombus forms, it can effectively stop the flow of blood through the area where it formed. In some cases, such thrombus dissolves harmlessly into the blood stream. In other cases, however, such thrombus can remain in the blood vessel, where it can partially or completely block the flow of blood. If the partially or completely blocked blood vessel supplies blood to a susceptible tissue, such as the brain, lungs, or heart, severe tissue damage can occur. For example, thrombosis of one of the carotid arteries can cause a stroke because of insufficient oxygen supply to important nerve centers within the skull. As another example, if one of the coronary arteries is 100% thrombosis, blood flow is stopped in this artery, resulting in a shortage of oxygen-carrying red blood cells to supply, for example, the muscle of the heart wall (myocardium). The lack of oxygen can reduce or prevent muscle activity, causing chest pain (angina pectoris) and even leading to necrosis of the myocardium, which leaves the heart with a degree of permanent damage. When myocardial cell death is widespread, the heart is no longer able to pump enough blood to keep the body healthy. In fact, a significant percentage of the more than 1.2 million heart attacks in the United States are caused by blood clots (thrombi) that form in the coronary arteries.

[0005] When signs of vascular obstruction, such as those that lead to stroke, appear, prompt action should be taken to reduce or eliminate the resulting tissue damage. Indeed, clinical data has shown that removal of the clot may be advantageous and even essential to improve outcomes. For example, in the peripheral vasculature, removal of the clot can reduce the need for amputation by 80%. The ultimate goal of all modalities for treating these conditions in the arterial or venous system is to quickly, completely, and cost-effectively remove the obstruction, i.e., recanalization. One approach is to treat the patient with thrombolytic drugs. However, these drugs do not rapidly dissolve the clot from the patient and are generally ineffective after a limited window, usually 2-3 hours, after the onset of symptoms due to the clot. Another approach involves thrombectomy, i.e., removal of the clot by aspiration, mechanical retrieval, or a combination thereof. Because mechanical retrieval usually involves a deployable mesh lattice such as a stent retriever, mechanical retrieval is often complex and risky to perform.

[0006] Aspiration thrombectomy is generally an effective and commonly used treatment for removing blood clots from blood vessels, particularly in cases of ischemic stroke. In a typical endovascular aspiration thrombectomy procedure, a catheter is introduced into the patient's vasculature until the distal end of the catheter is immediately proximal to the clot, and a vacuum is applied to the proximal end of the catheter, which draws at least a portion of the clot into the catheter for subsequent removal. Many aspiration systems are susceptible to tip blockage events when the clot being aspirated is excessively large compared to the aspiration conduit at the distal end of the catheter. The current state of the art for endovascular thrombectomy in ischemic stroke utilizes static loading. When a tip blockage event occurs, the pressure in the system drops rapidly to a level that often causes vaporization or cavitation of the aspirate in the system. As a result, water vapor can enter the system, which reduces the efficiency of aspiration, which in turn makes it more difficult, if not impossible, to draw the clot into the catheter.

[0007] In some cases, obstructions may be disrupted or forced through the aspiration conduit by dynamically or cyclically loading the aspiration conduit. This involves utilizing pressure pulsing to aspirate the obstructing clot. One method of cyclically loading the aspiration conduit uses a valve or similar configuration that is periodically actuated to achieve pressure pulsing by blocking the main stream flow. Typically, this is done manually or via an electromechanical or pneumatic valve that blocks aspiration flow to the pump for a specified time interval. In some cases, pressure sensing feedback has been proposed as a means to determine when to activate the valve. One cyclic filling method described in Simon S, Gray CP, Massenzo T, et al., "Exploring the efficacy of cyclic vs static aspiration in a cerebral thrombectomy model: an initial proof of concept study," Journal of NeuroInterventional Surgery, 2014;6:677-683, and PCT Publication WO2014151209A8, employs a venting mechanism that is automatically placed into an oscillating pulse mode in response to application of vacuum to the aspiration conduit. However, these methods require user intervention to cyclically fill the aspiration conduit in response to finding that the aspiration conduit is blocked (which would disturb the user if performing the aspiration procedure manually) or to cyclically fill the aspiration conduit immediately following application of vacuum to the aspiration conduit, thus reducing the efficiency of the aspiration procedure during free flow (i.e., when the aspiration conduit is not blocked).

[0008] Thus, there continues to be a need for a technique that periodically fills the aspiration conduit of an aspiration catheter only during no or low flow conditions. Summary of the Invention

[0009] According to a first aspect of the invention, a manifold comprises an aspiration outlet configured to fluidly couple to an aspiration source, and an aspiration inlet configured to fluidly couple to the aspiration catheter such that an aspiration flow path is formed between the aspiration catheter and the aspiration source. The aspiration flow path has a free flow absolute pressure that creates a negative free flow pressure differential between the aspiration outlet and the aspiration inlet. The manifold further comprises a relief inlet configured to fluidly communicate with a pressurized fluid source (e.g., a reservoir containing ambient air or liquid). The manifold further comprises a pressure oscillation assembly fluidly coupled between the relief inlet and the aspiration flow path. The pressure oscillation assembly is configured to operate between a normal mode in which fluid communication between the pressurized fluid source and the aspiration flow path is blocked, and an oscillation mode in which the pressure oscillation assembly pulses fluid communication between the pressurized fluid source and the aspiration flow path such that the negative pressure differential between the aspiration outlet and the aspiration inlet oscillates between a first negative pressure differential less than the free flow pressure differential and a second negative pressure differential greater than the free flow pressure differential.

[0010] According to a second aspect of the invention, a method of aspirating a thrombus from a patient comprises forming an aspiration flow path between an aspiration catheter positioned adjacent to the thrombus and a suction source. The aspiration flow path has a free-flow absolute pressure that creates a free-flow negative pressure differential between the suction source and the suction catheter. The method further comprises pulsing fluid communication between a pressurized fluid source (e.g., a reservoir containing ambient air or liquid) and the aspiration flow path, whereby the negative pressure differential between the suction source and the suction catheter oscillates between a first negative pressure differential less than the free-flow pressure differential and a second negative pressure differential greater than the free-flow pressure differential, thereby facilitating aspiration of the thrombus.

[0011] According to a third aspect of the invention, a manifold comprises an aspiration outlet configured to fluidly couple to an aspiration source, an aspiration inlet configured to fluidly couple to an aspiration catheter such that an aspiration flow path is formed between the aspiration catheter and the aspiration source, and a relief inlet configured to fluidly couple to a pressurized fluid source (e.g., a reservoir containing ambient air or liquid). The manifold further comprises a pressure oscillation assembly fluidly coupled between the relief inlet and the aspiration flow path. The pressure oscillation assembly is configured to operate between a normal mode in which it prevents fluid communication between the pressurized fluid source and the aspiration flow path, and an oscillation mode in which it pulses fluid communication between the pressurized fluid source and the aspiration flow path such that a negative pressure difference between the aspiration outlet and the aspiration inlet oscillates between a first negative pressure difference and a second negative pressure difference that is between 40 kPa and 90 kPa greater than the first negative pressure difference. In one embodiment, the second pressure difference is at least 60 kPa greater than the first pressure difference.

[0012] According to a fourth aspect of the invention, a method of aspirating a thrombus from a patient comprises forming an aspiration flow path between an aspiration catheter positioned adjacent to the thrombus and an aspiration source. The method further comprises pulsing fluid communication between a pressurized fluid source (e.g., a reservoir containing ambient air or liquid) and the aspiration flow path, whereby a negative pressure differential between the aspiration source and the aspiration catheter oscillates between a first negative pressure differential and a second negative pressure differential that is between 40 kPa and 90 kPa greater than the first negative pressure differential, thereby facilitating aspiration of the thrombus. In one method, the second pressure differential is at least 60 kPa greater than the first pressure differential.

[0013] According to a fifth aspect of the invention, a manifold comprises an aspiration outlet configured to fluidly couple to a suction source, an aspiration inlet configured to fluidly couple to the aspiration catheter such that an aspiration flow path is formed between the aspiration catheter and the aspiration source, and a relief inlet configured to fluidly couple to a pressurized fluid source (e.g., a reservoir containing ambient air or liquid). The manifold further comprises a pressure oscillation assembly fluidly coupled between the relief inlet and the aspiration flow path. The pressure oscillation assembly is configured to operate between a normal mode that prevents fluid communication between the pressurized fluid source and the aspiration flow path and an oscillation mode that simultaneously pulses fluid communication between the pressurized fluid source and the aspiration flow path at a first oscillation frequency and a second oscillation frequency different from the first oscillation frequency. In one embodiment, the second oscillation frequency is greater than the first oscillation frequency. For example, the first oscillation frequency can be in the range of 0.2 Hz to 10 Hz, and the second oscillation frequency can be in the range of 100 Hz to 400 Hz.

[0014] According to a sixth aspect of the invention, a method of aspirating a thrombus from a patient comprises forming an aspiration flow path between an aspiration catheter positioned adjacent to the thrombus and a suction source. The method further comprises pulsing fluid communication between a pressurized fluid source (e.g., a reservoir containing ambient air or liquid) and the aspiration flow path, whereby a negative pressure differential between the suction source and the aspiration catheter oscillates between a first negative pressure differential and a second negative pressure differential that is between 40 kPa and 90 kPa greater than the first negative pressure differential, thereby facilitating aspiration of the thrombus. In one method, the second pressure differential is at least 60 kPa greater than the first pressure differential.

[0015] In any of the manifolds described above, the pressure oscillation assembly may be a passive pressure oscillation assembly configured to be actuated to automatically switch from a normal mode to an oscillation mode in response to a lodged thrombus in the aspiration catheter and to automatically switch from the oscillation mode to the normal mode in response to the lodged thrombus being removed from the aspiration catheter. Similarly, any of the methods described above may include automatically pulsing fluid communication between the pressurized fluid source and the aspiration fluid line in response to a lodged thrombus in the aspiration catheter and automatically ceasing pulsing fluid communication between the pressurized fluid source and the aspiration fluid line in response to the lodged thrombus being removed from the aspiration catheter.

[0016] In any of the manifolds described above, pulsing of fluid communication between the pressurized fluid source and the aspiration flow path can oscillate the negative pressure difference between the aspiration outlet and the aspiration inlet between an actuation pressure difference that causes a gradual increase in the negative pressure difference between the aspiration outlet and the aspiration inlet, and a deactivation pressure difference that causes a gradual decrease in the negative pressure difference between the aspiration outlet and the aspiration inlet. Similarly, in any of the methods described above, pulsing of fluid communication between the pressurized fluid source and the aspiration flow path can oscillate the negative pressure difference between the aspiration source and the aspiration catheter between an actuation pressure difference that causes a gradual increase in the negative pressure difference between the aspiration source and the aspiration catheter, and a deactivation pressure difference that causes a gradual decrease in the negative pressure difference between the aspiration source and the aspiration catheter.

[0017] In any of the manifolds and methods described above, pulsing fluid communication between the pressurized fluid source and the aspiration fluid line causes a pressure pulse to propagate in the aspiration fluid line or a backflow of fluid to propagate in the aspiration fluid line. In any of the manifolds and methods described above, pulsing fluid communication between the pressurized fluid source and the aspiration fluid line in response to an embedded thrombus in the aspiration catheter includes blocking the aspiration fluid line such that the pulsing of fluid communication between the pressurized fluid source and the aspiration fluid line is directed to the aspiration catheter.

[0018] In any of the manifolds and methods described above, the passive pressure oscillation assembly may include a plunger cavity in fluid communication between the relief inlet and the suction flow passage, and a plunger assembly slidably disposed within the plunger cavity. The plunger assembly may be configured to block fluid communication between the pressurized fluid source and the suction flow passage through the plunger cavity when the passive pressure oscillation assembly is in a normal mode, and to pulse fluid communication between the pressurized fluid source and the suction flow passage at a first frequency when the passive pressure oscillation assembly is in an oscillation mode.

[0019] According to a seventh aspect of the invention, in a manifold including, but not limited to, any of the manifolds described above, the plunger assembly of the passive pressure oscillation assembly may include a rod, a first plunger head secured to the rod, and a second plunger head secured to the rod and spaced apart from the first plunger head, thereby forming a front plunger cavity region, a central plunger cavity region between the first and second plunger heads, and a rear plunger cavity region in the plunger cavity. Optionally, the plunger cavity may have a first portion having a diameter and a second portion having a diameter larger than the diameter of the first portion, the first plunger head having a diameter and the second plunger head having a diameter larger than the diameter of the first plunger head. The first plunger head may be configured to be displaced within the first portion and the second plunger head may be configured to be displaced within the second portion.

[0020] The passive pressure oscillation assembly may further include an inlet channel in fluid communication between the relief inlet and the front plunger cavity region, an outlet channel in conditional fluid communication between the central plunger cavity region and the aspiration flow path, and a bypass channel in conditional fluid communication between the front plunger cavity region and the central plunger cavity region. The plunger assembly may be configured to maintain the first plunger head in a closed position within the plunger cavity to prevent fluid communication between the front plunger cavity region and the central plunger cavity region via the bypass channel and to maintain the second plunger head in a closed position within the plunger cavity to prevent fluid communication between the central plunger cavity region and the aspiration flow path via the outlet channel, thereby preventing fluid communication between the pressurized fluid source and the aspiration flow path via the plunger cavity, when the passive pressure oscillation assembly is in a normal mode. The plunger assembly may further be configured, when the passive pressure oscillation assembly is in an oscillation mode, to displace the first plunger head from a closed position in the plunger cavity to an open position to enable fluid communication between the front plunger cavity region and the central plunger cavity region via the bypass channel, and further to displace the second plunger head from a closed position in the plunger cavity to an open position to enable fluid communication between the central plunger cavity region and the aspiration flow path, and then to pulse fluid communication between the pressurized fluid source and the aspiration flow path at a first frequency by returning the first plunger head and the second plunger head from the open position to the closed position.

[0021] The passive pressure oscillation assembly may optionally include a spring configured to apply a biasing force to the plunger assembly to maintain the first and second plunger heads in a closed position within the plunger cavity during operation of the passive pressure oscillation assembly in a normal mode, in which case the plunger assembly may be configured to, in response to pressure applied by fluid supplied to the plunger assembly from the pressurized fluid source through the inlet channel during operation of the passive pressure oscillation assembly in an oscillation mode, overcome the biasing force applied to the plunger assembly by the spring to displace the first and second plunger heads from a closed position to an open position within the plunger cavity, and thereafter compensate for the biasing force applied to the plunger assembly by the spring to return the first and second plunger heads from the open position to the closed position. In this case, the passive pressure oscillation assembly may include a pressure tap channel in fluid communication between the suction flow path and the rear plunger cavity region, and the plunger assembly is configured to return the first plunger head and the second plunger head from the open position to the closed position in response to pressure exerted by fluid supplied from the suction flow path through the pressure tap channel to supplement the biasing force exerted on the plunger assembly by the spring during operation of the passive pressure oscillation assembly in the oscillation mode.

[0022] The manifold may optionally include a fluid-actuated valve (e.g., a diaphragm valve) disposed in the suction flow passage and a suction shutoff channel in conditional fluid communication between the central plunger cavity region and the fluid-actuated valve, wherein the second plunger head may be configured to block fluid communication between the central plunger cavity region and the fluid-actuated valve via the suction shutoff channel and allow fluid communication between the rear plunger cavity region and the fluid-actuated valve via the suction shutoff channel when in a closed position, and to allow fluid communication between the central plunger cavity region and the fluid-actuated valve via the suction shutoff channel and block fluid communication between the rear plunger cavity region and the fluid-actuated valve via the suction shutoff channel when in an open position.

[0023] The manifold can optionally include a pressure equalization channel in conditional fluid communication between the aspiration flow passage and the central plunger cavity region, in which case the first plunger head can be configured to allow fluid communication between the aspiration flow passage and the central plunger cavity region when in a closed position and to prevent fluid communication between the aspiration flow passage and the central plunger cavity region when in an open position.

[0024] The manifold can optionally include a resonator (e.g., a paddle wheel) disposed in the outlet channel configured to pulse fluid communication between the plunger cavity and the aspiration flow passage at a second frequency different from (e.g., greater than) the first frequency when the passive pressure oscillation assembly is in an oscillation mode.

[0025] Other and further aspects and features of the disclosed inventive embodiments will become apparent from the following detailed description considered in conjunction with the accompanying drawings. [Brief description of the drawings]

[0026] The drawings illustrate the design and utility of preferred embodiments of the disclosed invention, in which similar elements are indicated with common reference numerals. Please note that the drawings are not to scale, and that elements of similar structure or function are indicated by similar reference numerals throughout the several views. Furthermore, please note that the drawings are intended only to assist in the description of the embodiments. These drawings are not intended to be comprehensive descriptions of the invention, nor are they intended to limit the scope of the invention, which is defined only by the appended claims and their equivalents. In addition, a depicted embodiment of the disclosed invention need not have all the aspects or advantages depicted. Furthermore, an aspect or advantage described in conjunction with a particular embodiment of the disclosed invention is not necessarily limited to this embodiment only, and may be implemented in any other embodiment, even if not depicted.

[0027] In order that the manner in which the above-mentioned advantages and objects of the disclosed invention may be better understood, as well as other advantages and objects thereof, a more particular description of the disclosed invention as briefly described above will be rendered by reference to specific embodiments of the invention which are illustrated in the accompanying drawings, in which the invention will be described and explained with more specificity and detail, with the understanding that these drawings depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention, with the understanding that the drawings depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention, with the aid of which the invention will be described and explained with greater specificity and detail.

[0028] [Figure 1] FIG. 1 is a block diagram illustrating one embodiment of an aspiration system constructed in accordance with the present invention. [Diagram 2] 2 is a plan view of an exemplary suction catheter for use in the aspiration system of FIG. 1. [Diagram 3] 3 is a plan view of the distal end of the aspiration catheter of FIG. 2 used to aspirate vascular obstruction from a patient's vasculature. [Figure 4] 2 is a timing diagram illustrating a negative pressure differential over time between a pressurized fluid source and an aspiration flow path created within the aspiration system of FIG. 1. [Diagram 5] FIG. 2 is a block diagram illustrating one embodiment of a passive pressure oscillation assembly used within the aspiration system of FIG. 1. [Figure 6] 2 is a block diagram illustrating another embodiment of a passive pressure oscillation assembly used in the aspiration system of FIG. 1. [Figure 7] 2 is a block diagram illustrating yet another embodiment of a passive pressure oscillation assembly for use in the aspiration system of FIG. 1. [Figure 8A] 2 is a top view of one embodiment of a passive pressure vibration assembly used in the aspiration system of FIG. 1, particularly showing the passive pressure vibration assembly in a closed position. [Figure 8B] FIG. 8B is a top view of the passive pressure vibration assembly of FIG. 8A, particularly showing the passive pressure vibration assembly in an open position. [Figure 9A] 2 is a plan view of another embodiment of a passive pressure vibration assembly for use in the aspiration system of FIG. 1, particularly showing the passive pressure vibration assembly in a closed position. [Figure 9B] FIG. 9B is a top view of the passive pressure vibration assembly of FIG. 9A, particularly showing the passive pressure vibration assembly in an open position. [Figure 10A] 2 is a plan view of another embodiment of a passive pressure vibration assembly for use in the aspiration system of FIG. 1, particularly showing the passive pressure vibration assembly in a first state. [Figure 10B] 10B is a top view of the passive pressure vibration assembly of FIG. 10A, particularly showing the passive pressure vibration assembly in a second state. [Figure 10C] 10B is a top view of the passive pressure vibration assembly of FIG. 10A, particularly showing the passive pressure vibration assembly in a third state. [Figure 10D] 10B is a top view of the passive pressure vibration assembly of FIG. 10A, particularly showing the passive pressure vibration assembly in a fourth state. [Figure 11A] 2 is a plan view of another embodiment of a passive pressure vibration assembly for use in the aspiration system of FIG. 1, particularly showing the passive pressure vibration assembly in a closed position. [Figure 11B] FIG. 11B is a top view of the passive pressure vibration assembly of FIG. 11A, particularly showing the passive pressure vibration assembly in an open position. [Figure 12] 2 is a flow chart illustrating one method of operating the aspiration system of FIG. 1 to aspirate vascular obstruction from a patient's vasculature. [Figure 13A] 11 is a plan view of yet another embodiment of a passive pressure vibration assembly for use in the aspiration system of FIG. 1, particularly showing the passive pressure vibration assembly in a first state. [Figure 13B] 13B is a plan view of the passive pressure vibration assembly of FIG. 13A, particularly showing the passive pressure vibration assembly in a second state. [Figure 13C] 13B is a plan view of the passive pressure vibration assembly of FIG. 13A, particularly showing the passive pressure vibration assembly in a third state. [Figure 13D] FIG. 13B is a plan view of the passive pressure vibration assembly of FIG. 13A, particularly showing the passive pressure vibration assembly in a fourth state. [Figure 13E] FIG. 13B is a plan view of the passive pressure vibration assembly of FIG. 13A, particularly showing the passive pressure vibration assembly in a fifth state. [Figure 14] FIG. 14 is a timing diagram illustrating the negative pressure differential over time between the pressurized fluid source and the aspiration flow path that occurs in the aspiration system of FIG. 1 when using the passive pressure oscillation assembly of FIGS. 13A-13E. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] 1, one embodiment of a vascular occlusion material aspiration system 10 constructed in accordance with the disclosed invention will be described. The vascular occlusion material aspiration system 10 generally includes an aspiration catheter 12, a suction source 14, a pressurized fluid source 16, a tissue collection container 18, and a manifold 20.

[0030] 2 and 3, the aspiration catheter 12 comprises an elongate catheter body 22 and an aspiration conduit 24 (shown in phantom in FIG. 3) extending through the catheter body 22 between a proximal end 28 and a distal end 30 of the catheter body 22. The proximal end 28 of the aspiration catheter 12 remains external to the patient 1 and is accessible to an operator during use of the vascular occlusion material aspiration system 10, while the distal end 30 of the catheter body 22 is sized and dimensioned to reach vascular occlusion material 2 (e.g., blood clots) at a remote location in the patient's vasculature 1, as best shown in FIG. 3. The aspiration catheter 12 comprises a distal inlet port 32 in communication with the aspiration conduit 24 of the aspiration catheter 12, into which the vascular occlusion material 2 is aspirated by the aspiration catheter 12.

[0031] The aspiration catheter 12 can have multiple regions along its length having various configurations and / or properties. For example, the distal portion of the catheter body 22 can have a smaller outer diameter than the proximal portion of the catheter body 22 to reduce the profile of the distal portion of the catheter body 22 and to aid in navigation within tortuous vasculature. Additionally, the distal portion of the catheter body 22 can have a higher flexibility than the proximal portion of the catheter body 22. Generally, the proximal portion of the catheter body 22 can be formed from a material having a higher stiffness than the distal portion of the catheter body 22 such that the proximal portion has sufficient pushability to advance through the patient's vasculature 1, whereas the distal portion can be formed from a material having a higher flexibility such that the distal portion can remain flexible and more easily follow a guidewire to access remote locations within the tortuous regions of the vasculature 1. The catheter body 22 may be constructed from a suitable polymeric material, metal, and / or alloy, such as polyethylene, stainless steel, or other suitable biocompatible material, or a combination thereof. In some examples, the proximal portion of the catheter body 22 may have a reinforcing layer, such as a braided or coiled layer, to improve the pushability of the catheter body 22. The catheter body 22 may have a transition region between the proximal and distal portions of the catheter body 22.

[0032] Referring again to FIG. 1, the suction source 14 may be, for example, a conventional pump (e.g., a rotary vane pump, a diaphragm pump, a peristaltic pump, or a Venturi pump) or a syringe configured to generate a low pressure within the suction conduit 26 of the suction catheter 12. This low pressure is less than the ambient air pressure and may therefore be considered a vacuum that can aspirate the vascular occlusion material 2 within the suction conduit 26 of the suction catheter 12. The vascular occlusion material 2 may be sucked into the suction catheter 12 in one piece, or may be broken into multiple pieces and sucked piece by piece into the suction catheter 12. During operation, the suction source 14 provides a base level of vacuum to the suction catheter 12. This vacuum level may be controlled and adjusted as needed by the user to aspirate tissue. The level of vacuum may be set constant or the vacuum level may be varied by the user over any given time during the tissue removal procedure.

[0033] The pressurized fluid source 16 may be, for example, a reservoir containing a liquid such as saline (e.g., a saline drip bag), or ambient air. It should be appreciated that the fluid source 16 is pressurized to a degree that causes the fluid to have a pressure higher than the lowest vacuum level achieved within the suction conduit 24 of the suction catheter 12 during operation of the suction source 14. Thus, even though the fluid source 16 of the illustrated embodiment may be under a lower pressure (i.e., ambient pressure or one absolute atmosphere), the fluid source 16 is pressurized relative to the pressure experienced by the suction conduit 24 of the suction catheter 12 during operation of the suction source 14. The tissue collection container 18 may be any suitable container that is fluidly connected to the suction source 14 via an exhaust line to allow for the aspirated tissue to be collected and disposed of in a sterile manner. Alternatively, the tissue collection container 18 may be located between the suction source 14 and the suction catheter 12.

[0034] The suction catheter 12, suction source 14, pressurized fluid source 16, and tissue collection container 18 may be conventional in nature.

[0035] In contrast, the manifold 20 is non-conventional and provides an interface between the suction catheter 12, the suction source 14, and the pressurized fluid source 16 in a manner that assists the suction catheter 12 in aspirating the thrombus 2 during zero or low flow conditions (e.g., when a thrombus 2 blocks the suction conduit 24 of the suction catheter 12 or there is otherwise a flow anomaly within the suction circuit of the system 10), while maximizing the efficiency of the aspiration process during free flow conditions (e.g., when the suction conduit 24 is not blocked and the suction circuit of the system 10 is operating as intended).

[0036] The manifold 20 includes a suction inlet 36 coupled to the suction catheter 12 and a suction outlet 38 coupled to the suction source 14, and a relief inlet 40 coupled to the pressurized fluid source 16, for forming a suction flow path 46 from the suction catheter 12 to the suction source 14. The manifold 20 may be coupled to the suction catheter 12, suction source 14, and pressurized fluid source 16 through the use of conventional catheters (not shown), or alternatively may be integrated thereto without the use of connectors. The manifold 20 further includes a passive pressure oscillation assembly 44 coupled between the relief inlet 40 and the suction flow path 46. Importantly, the passive pressure oscillation assembly 44 is configured to dynamically fill (i.e., rapidly change vacuum levels) the suction conduit 24 of the suction catheter 12, and specifically to periodically fill the suction conduit 24 only during zero or low flow conditions. The passive pressure vibration assembly 44 accomplishes this without user input and without the use of electronic sensors. Additionally, the passive pressure vibration assembly 44 can be made very compact so that it can fit within the manifold 20 with little increase in size. It may not be possible for the passive pressure vibration assembly 44 to simply block the relief inlet 40.

[0037] To this end, the passive pressure oscillation assembly 44 is configured to be operated between a normal mode in which fluid communication along the relief path 48 between the pressurized fluid source 16 and the aspiration flow path 46 is prevented (so that the absolute pressure in the aspiration flow path 46 remains relatively constant and is acted upon only by the aspiration source 14) and an oscillation mode in which fluid communication along the relief path 48 between the pressurized fluid source 16 and the aspiration flow path 46 is pulsed (so that the absolute pressure in the aspiration flow path 46 oscillates within a predetermined frequency range). The passive pressure oscillation assembly 44 is configured to be activated to switch from the normal mode to the oscillation mode in response to an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or other flow anomaly in the aspiration conduit of the system 10, and conversely to be activated to switch from the oscillation mode to the normal mode in response to an obstruction being removed or cleared from the aspiration conduit 24 of the aspiration catheter 12 or other flow anomaly in the aspiration circuit of the system 10 being resolved. In the embodiment shown, pulsing of the fluid communication between the pressurized fluid source 16 and the aspiration fluid line 46 causes pressure pulses at a predetermined frequency to propagate along the aspiration conduit 24 of the aspiration catheter 12. Concurrently, pulsing of the fluid communication between the pressurized fluid source 16 and the aspiration fluid line 46 causes a backflow of fluid to propagate along the aspiration conduit 24 of the aspiration catheter 12.

[0038] The passive pressure oscillation assembly 44 may be designed to pulse the fluid communication along the relief path 48 between the pressurized fluid source 16 and the aspiration flow path 46 at a predetermined frequency, such that the absolute pressure in the aspiration flow path 46 oscillates at the predetermined frequency. As an example, the predetermined frequency of pressure oscillations induced in the aspiration flow path 46 by the passive pressure oscillation assembly 44 may be matched to the natural resonance of the fluid column in the aspiration conduit 24 of the aspiration catheter 12, such that the energy transfer from the aspiration flow path 46 to the aspiration conduit 24 of the aspiration catheter 12 and thus the propagation of the pressure pulse along the aspiration conduit 24 of the aspiration catheter 12 is maximized. As another example, the predetermined frequency of pressure oscillations induced in the aspiration flow path 46 by the passive pressure oscillation assembly 44 may be selected based on the viscoelastic properties of the thrombus 2 expected to be drawn by the aspiration catheter 12. That is, an occlusive thrombus 2 having a softer consistency may be more susceptible to maceration and then to being sucked in in response to relatively low frequency and high amplitude vibrations, whereas an occlusive thrombus 2 having a harder consistency may be more susceptible to maceration and then to being sucked in in response to relatively high frequency and low amplitude vibrations.

[0039] The vibration of the passive pressure oscillation assembly 44 can optionally emit sound and serve as an automatic audio signal to the user that an obstruction has occurred in the aspiration conduit 24 of the aspiration catheter 12. In an optional embodiment, the passive pressure oscillation assembly 44 can be designed to pulse the fluid communication between the pressurized fluid source 16 and the aspiration channel 46 at two or more different frequencies simultaneously. For example, because the determination of the type of material properties of the thrombus 2 is not known, it may be desirable to pulse the fluid communication between the pressurized fluid source 16 and the aspiration channel 46 at a relatively high frequency and a relatively low frequency simultaneously, such that the pressure profile in the aspiration conduit 24 of the aspiration catheter 12 is a composite of low and high frequency oscillations.

[0040] In the embodiment shown, the passive pressure oscillation assembly 44 utilizes the correlation between different flow conditions of the aspiration catheter 12 and the resulting fluid pressure levels within the aspiration flow path 46. Specifically, in the case of a zero flow or low flow condition, in which an obstruction is present within the aspiration conduit 24 of the aspiration catheter 12 or other flow anomalies exist within the aspiration circuit of the system 10, it is expected that the vacuum within the aspiration flow path 46 will rapidly increase (i.e., the absolute pressure within the aspiration flow path 46 will rapidly decrease), thereby increasing the negative pressure differential between the external ambient pressure and the aspiration flow path 46 to a very high level (e.g., at least −55 kPa), which may further cause evaporation or cavitation of aspirant within the aspiration flow path 46 in the absence of intervention by the passive pressure oscillation assembly 44 (e.g., if such negative pressure differential is less than −95 kPa). In contrast, in the case of a free-flow condition, where the aspiration catheter 12 is not blocked or flow anomalies in the aspiration circuit of the system 10 are otherwise resolved, it is expected that the vacuum in the aspiration flow path 46 will drop sharply (i.e., the absolute pressure in the aspiration flow path 46 will increase sharply) to a lower level (e.g., below −50 kPa), thereby reducing the negative pressure differential between the external ambient pressure and the aspiration flow path 46 to a lower level. The passive pressure oscillation assembly 44 keys off these negative pressure differentials when switching between normal and oscillation modes.

[0041] To this end, the passive pressure oscillation assembly 44 includes an inlet port 50 (shown in FIG. 5) in fluid communication with the pressurized fluid source 16 and an outlet port 52 (shown in FIG. 5) in fluid communication with the suction passage 46, such that the passive pressure oscillation assembly 44 is exposed to a negative pressure differential between the pressurized fluid source 16 and the fluid in the suction passage 46. The passive pressure oscillation assembly 44 is activated to switch from normal mode to oscillation mode and vice versa based on this negative pressure differential.

[0042] Specifically, the passive pressure oscillation assembly 44 is designed to be activated to switch from a normal mode to an oscillation mode in response to a drop in absolute pressure in the aspiration flow path 46 to create a negative activation pressure differential between the inlet port 50 and the outlet port 52 of the passive pressure oscillation assembly 44 that correlates to a negative pressure difference between the aspiration flow path 46 and the blood pressure experienced by the aspiration catheter 12 when the aspiration conduit 24 of the aspiration catheter 12 is occluded or the aspiration circuit of the system 10 is otherwise experiencing a flow anomaly (zero flow or low flow condition), and conversely, the passive pressure oscillation assembly 44 is designed to create a negative cessation pressure differential between the inlet port 50 and the outlet port 52 of the passive pressure oscillation assembly 44 that correlates to a negative pressure difference between the aspiration flow path 46 and the blood pressure experienced by the aspiration catheter 12 when the aspiration conduit 24 of the aspiration catheter 12 is not occluded or the aspiration circuit of the system 10 is operating as intended (free flow condition). The passive pressure oscillator 44 is designed to be activated to switch from the oscillation mode to the normal mode in response to an increase in absolute pressure in the aspiration flow path 46 that creates a negative stopping pressure differential between the inlet port 50 and the outlet port 52 of the passive pressure oscillator assembly 44. In particular, it is important that the stopping pressure differential is always negative so that stuck thrombus 2 is not expelled from the distal end 30 of the catheter body 22.

[0043] In the case where the pressurized fluid source 16 is the external ambient pressure, the negative pressure difference for actuation of the passive pressure oscillation assembly 44 during zero or low flow conditions differs substantially by a known offset from the negative pressure difference between the aspiration flow path 46 and the blood pressure experienced by the aspiration catheter 12, and similarly, the negative pressure difference for deactivation of the passive pressure oscillation assembly 44 during free flow conditions differs substantially by a known offset from the negative pressure difference between the aspiration flow path 46 and the blood pressure experienced by the aspiration catheter 12. In this manner, the passive pressure oscillation assembly 44 may be configured to self-calibrate to the time-varying external environment.

[0044] In this case, the design range of the negative pressure differential for actuation of the passive pressure oscillation assembly 44 may have an upper limit of -55 kPa such that the passive pressure oscillation assembly 44 will be rapidly triggered to switch from normal mode to oscillation mode, but not so low as to trigger the passive pressure oscillation assembly 44 to switch from normal mode to oscillation mode during actuation and active and productive suction of the clot 2 into the distal end 30 of the aspiration catheter 12, and may further have a lower limit of -95 kPa to ensure that the boiling point of the fluid in the aspiration flow path 46 (i.e., blood at 37°C) is not reached. However, the passive pressure oscillation assembly 44 may be designed to have a negative pressure differential for actuation anywhere within the range of -55 kPa to -95 kPa. The deactivation negative pressure differential of the passive pressure oscillation assembly 44 should be designed relative to the activation negative pressure differential of the passive pressure oscillation assembly 44 and is preferably significantly lower than the activation negative pressure differential (e.g., in the range of 10 kPa to 25 kPa greater than the activation negative pressure differential), so that hysteresis is built into the passive pressure oscillation assembly 44. This ensures that the pressure oscillations induced in the aspiration flow path 46 by the passive pressure oscillation assembly 44 do not inadvertently activate the passive pressure oscillation assembly 44 back to normal mode until the aspiration catheter 12 is in a free-flowing state. In low resonant frequency scenarios, the activation and deactivation negative pressure differentials may be equal, and in such cases the passive pressure oscillation assembly 44 will be reactivated after every increase in the negative pressure differential in the aspiration flow path 46 to switch from normal mode to oscillation mode in response to a drop in absolute pressure in the aspiration flow path 46 caused by the aspiration source 18.

[0045] In an optional embodiment, the passive pressure oscillation assembly 44 may be designed to have multiple actuation negative pressure differences and thus multiple deactivation negative pressure differences. For example, the passive pressure oscillation assembly 44 may be designed to have a first actuation negative pressure difference, e.g., -50 kPa, such that the passive pressure oscillation assembly 44 is activated to switch from a normal mode to a relatively high-speed oscillation mode to assist in sucking the thrombus 2 into the distal end 30 of the aspiration catheter 12 before the aspiration conduit 24 of the aspiration catheter 12 is blocked. Operation of the passive pressure oscillation assembly 44 in the relatively high-speed oscillation mode may propagate high-frequency but low-volume pulses along the aspiration conduit 24 of the aspiration catheter 12, thereby assisting in the sucking of the thrombus 2 without excessively impeding the volumetric flow rate. The passive pressure oscillation assembly 44 may be further designed to have a second actuation negative pressure difference, e.g., -55 kPa, such that the passive pressure oscillation assembly 44 is activated to operate in a relatively slow oscillation mode to assist in dislodging the occlusive thrombus 2 in the distal end 30 of the aspiration catheter 12. The operation of the passive pressure oscillation assembly 44 in the relatively fast oscillation mode may propagate low frequency but high volume pulses along the aspiration conduit 24 of the aspiration catheter 12 in an attempt to dislodge the occlusive thrombus 2 from the distal end 30 of the aspiration catheter 12. Thus, when the thrombus 2 is sucked in without blocking the distal end 30 of the aspiration catheter 12, only the relatively fast oscillation mode of the passive pressure oscillation assembly 44 is activated, whereas when the thrombus 2 blocks the distal end 30 of the aspiration catheter 12, only the relatively slow oscillation mode of the passive pressure oscillation assembly 44 is activated.

[0046] It should be appreciated that the pressurized fluid source 16 may have a pressure significantly different from the external ambient pressure experienced by the aspiration catheter 12, in which case during zero or low flow conditions the negative pressure difference for actuation of the passive pressure oscillation assembly 44 will be significantly different from the negative pressure difference between the aspiration flow path 46 and the surrounding external environment experienced by the aspiration catheter 12, and similarly during free flow conditions the negative pressure difference for shutting down the passive pressure oscillation assembly 44 will be significantly different from the negative pressure difference between the aspiration flow path 46 and the surrounding external environment experienced by the aspiration catheter 12. In this latter case, this difference may be taken into account when designing the negative pressure difference for actuation and shutting down of the passive pressure oscillation assembly 44. For example, if the pressurized fluid source 16 has a pressure significantly higher than the external ambient pressure, the passive pressure oscillation assembly 44 must be designed to have a larger negative pressure difference for actuation and shutting down to account for the higher fluid pressure that the inlet port 50 of the passive pressure oscillation assembly 44 will be subjected to.

[0047] 4, the suction source 14 is first activated so that the suction catheter 12 is in a free-flow state between any times t0 and t1, and the negative pressure difference between the absolute pressure in the suction flow passage 46 and the external ambient pressure experienced by the suction catheter 12 (in this case, the negative pressure difference between the inlet port 50 and the outlet port 52 of the passive pressure oscillation assembly 44) is the negative pressure difference during free-flow, where the suction catheter 12 draws in only blood. During this time, the passive pressure oscillation assembly 44 remains in normal mode. In this way, the suction efficiency of the system 10 is maximized during the free-flow state.

[0048] Between any times t1 and t2, thrombus 2 is actively sucked into distal end 30 of aspiration catheter 12, such that the negative pressure differential between the absolute pressure in aspiration flow path 46 and the external ambient pressure experienced by aspiration catheter 12 drops below the free-flow negative pressure differential for operation of passive pressure oscillation assembly 44 (designed for zero or low flow conditions indicative of a blocked aspiration catheter 12 or flow anomalies in the aspiration conduit of system 10). At any times t0 and t2, passive pressure oscillation assembly 44 remains in normal mode.

[0049] However, at any time t2, the aspiration catheter 12 becomes blocked with a thrombus 2, causing the negative pressure difference between the absolute pressure in the aspiration flow path 46 and the external ambient pressure experienced by the aspiration catheter 12 to suddenly drop to an actuation negative pressure difference, which in the illustrated case is -75 kPa. Thus, at any time t2 or shortly thereafter, the blocked aspiration catheter 12 (zero or low flow state) activates the passive pressure oscillation assembly 44 to switch from normal to oscillation mode, causing pressure oscillations in the aspiration flow path 46, which in turn cause pressure pulses to propagate along the aspiration conduit 24 of the aspiration catheter 12, thereby assisting in dislodging the occlusive thrombus 2 at the distal end 24 of the aspiration catheter 12 at any time t3. Dislodging the occlusive thrombus 2 at the distal end 24 of the aspiration catheter 12 causes the negative pressure difference between the absolute pressure in the aspiration flow path 46 and the external ambient pressure experienced by the aspiration catheter 12 to suddenly increase to a level above the stop negative pressure difference, which in the illustrated case is -50 kPa. Thus, at any time t3 or shortly after any time t3, an unobstructed suction catheter 12 (free flow condition) activates the passive pressure oscillation assembly 44 to switch from oscillation mode to normal mode, thereby ceasing the pressure oscillations in the suction flow path 46, thereby ceasing the pressure pulses propagating along the suction conduit 24 of the suction catheter 12.

[0050] In an optional embodiment in which the passive pressure oscillation assembly 44 operates in multiple oscillation modes (e.g., a high frequency oscillation mode and a low frequency oscillation mode), the passive pressure oscillation assembly 44 may be operated in the high frequency oscillation mode between any time t1 and any time t2, such that active suction of the thrombus 2 into the distal end 30 of the suction catheter 12 is assisted by a high frequency but low volume pressure pulse propagating along the suction conduit 24 of the suction catheter 12, and further, in the case where the thrombus 2 blocks the distal end 30 of the suction catheter 12, the passive pressure oscillation assembly 44 may be operated in the low frequency oscillation mode between any time t2 and any time t3, such that removal of the occlusive thrombus 2 from the distal end 30 of the suction catheter 12 is assisted by a low frequency but high volume pressure pulse propagating along the suction conduit 24 of the suction catheter 12.

[0051] 5, the passive pressure oscillator assembly 44 includes a pressure actuated valve 54 and a fluid resonator 56 (e.g., a hydraulic or pneumatic resonator). The pressure actuated valve 54 is configured to open in response to a decrease in absolute pressure in the aspiration flow passage 28 creating an actuating negative pressure differential between the inlet port 50 and the outlet port 52 (e.g., indicative of an obstruction in the aspiration conduit 24 of the aspiration catheter 12) to allow fluid flow from the pressurized fluid source 16 through the pressure actuated valve 54, and conversely, to close in response to an increase in absolute pressure in the aspiration flow passage 28 creating an actuating negative pressure differential between the inlet port 50 and the outlet port 52 (e.g., indicative of an obstruction having been removed or cleared from the aspiration conduit 24 of the aspiration catheter 12) to prevent fluid flow from the pressurized fluid source 16 through the pressure actuated valve 54. A fluid resonator device 56 is configured to resonate at a predetermined frequency in response to fluid flow from the pressurized fluid source 16 through the pressure-operated valve 54 to pulse fluid communication between the pressurized fluid source 16 and the suction passage 46 at the predetermined frequency, and conversely, is configured to cease resonating in response to an interruption in the flow of fluid from the pressurized fluid source 16 through the pressure-operated valve 54.

[0052] In one embodiment, the pressure actuated valve 54 and the fluid resonator 56 are mechanically coupled to each other. In this embodiment, the mechanically coupled pressure actuated valve 54 and the fluid resonator 56 must be designed dependently to meet both opening and resonant frequency criteria, but the mechanical coupling of the pressure actuated valve 54 and the fluid resonator 56 to each other results in a simpler mechanical design that may be more easily implemented in the passive pressure oscillation assembly 44. In another embodiment, the pressure actuated valve 54 and the fluid resonator 56 are mechanically separated from each other. In this embodiment, the mechanically separated pressure actuated valve 54 and the fluid resonator 56 allow the opening / closing criteria and the resonant oscillation criteria to be independently optimized, but still results in a mechanical design that may be more complex than the mechanical design of the embodiment having the mechanically coupled pressure actuated valve 54 and the fluid resonator 56.

[0053] As discussed above, the passive pressure oscillation assembly 44 may optionally be designed to have two actuating negative pressure differentials and / or two deactivating negative pressure differentials and / or to pulse fluid communication between the pressurized fluid source 16 and the suction passage 46 simultaneously at two different frequencies.

[0054] In an alternative embodiment, the fluid resonator device 56 automatically responds to an obstruction in the suction catheter 12 by blocking the suction flow path 46 and pulsing fluid communication between the pressurized fluid source 50 and the suction flow path 46, thereby directing pulsed fluid communication between the pressurized fluid source 50 and the suction flow path 46 toward the suction catheter 12.

[0055] 6, an alternative embodiment of a passive pressure vibration assembly 44' includes two parallel sets of pressure actuated valve assemblies and fluid resonators. Specifically, the passive pressure vibration assembly 44' includes a first pressure actuated valve 54a, a first fluid resonator 56a, a second pressure actuated valve 54b, and a second fluid resonator 56b.

[0056] The first pressure operated valve 54a is configured to open in response to a decrease in absolute pressure in the suction passage 28 creating a first actuating negative pressure differential between the inlet port 50 and the outlet port 52 to allow fluid flow from the pressurized fluid source 16 through the first pressure operated valve 54a, and conversely to close in response to an increase in absolute pressure in the suction passage 28 creating a first blocking negative pressure differential between the inlet port 50 and the outlet port 52 to prevent fluid flow from the pressurized fluid source 16 through the pressure operated valve 54. The first fluid resonator 56a is configured to resonate at a first predetermined frequency in response to fluid flow from the pressurized fluid source 16 through the first pressure operated valve 54a to pulse fluid communication between the pressurized fluid source 16 and the suction passage 46 at this first predetermined frequency, and conversely to stop resonating in response to blocking of fluid flow from the pressurized fluid source 16 through the first pressure operated valve 54a.

[0057] The second pressure operated valve 54b is configured to open in response to a decrease in absolute pressure in the suction passage 28 creating a second actuating negative pressure differential between the inlet port 50 and the outlet port 52 to allow fluid flow from the pressurized fluid source 16 through the second pressure operated valve 54b, and conversely to close in response to an increase in absolute pressure in the suction passage 28 creating a second blocking negative pressure differential between the inlet port 50 and the outlet port 52 to prevent fluid flow from the pressurized fluid source 16 through the pressure operated valve 54. The second fluid resonator 56b is configured to resonate at a second predetermined frequency in response to fluid flow from the pressurized fluid source 16 through the second pressure operated valve 54b to pulse fluid communication between the pressurized fluid source 16 and the suction passage 46 at this second predetermined frequency, and conversely to stop resonating in response to blocking of fluid flow from the pressurized fluid source 16 through the second pressure operated valve 54b.

[0058] The first and second actuation negative pressure differentials may be equal (e.g., both indicate an obstruction in the aspiration conduit 24 of the aspiration catheter 12) or may be different (e.g., one indicates active suction of a clot into the aspiration catheter 12 and the other indicates that the aspiration conduit 24 of the aspiration catheter 12 is blocked). The first and second stop negative pressure differentials may be equal (e.g., both indicate suction or removal of an obstruction in the aspiration conduit 24 of the aspiration catheter 12). However, in alternative embodiments, the first and second stop negative pressure differentials may be different. The first and second predetermined frequencies may be equal or different (e.g., one is a relatively high frequency for disrupting an obstructing clot 2 having a lower viscosity and the other is a relatively low frequency for disrupting an obstructing clot 2 having a higher viscosity). The first pressure actuated valve 54a and the first fluid resonator 56a may be mechanically coupled to each other or mechanically isolated from each other, and similarly the second pressure actuated valve 54b and the second fluid resonator 56b may be mechanically coupled to each other or mechanically isolated from each other. Furthermore, the first pressure actuated valve 54a and the second pressure actuated valve 54b may be coupled to each other to essentially form a valve assembly having multiple outlets that distribute flow to one or the other or both of the fluid resonators 56a, 56b in response to various levels of a single sensed pressure differential.

[0059] Although the passive pressure vibration assembly 44' is shown in FIG. 6 as having only two sets of pressure actuated valve assemblies and fluid resonators in parallel, the passive pressure vibration assembly 44' may alternatively have more than two sets of pressure actuated valve assemblies and fluid resonators in parallel.

[0060] Referring to FIG. 7, another alternative embodiment of a passive pressure oscillation assembly 44'' includes a single pressure actuated valve 54, a first fluid resonator 56a, and a second fluid resonator 56b.

[0061] The pressure-activated valve 54 is configured to open in response to a decrease in absolute pressure in the aspiration flow passage 28 creating an actuating negative pressure differential between the inlet port 50 and the outlet port 52 to allow fluid flow from the pressurized fluid source 16 through the first pressure-activated valve 54, and conversely, to close in response to an increase in absolute pressure in the aspiration flow passage 28 creating a stopping negative pressure differential between the inlet port 50 and the outlet port 52 (e.g., indicating that an obstruction has been removed or cleared from the aspiration conduit 24 of the aspiration catheter 12) to prevent fluid flow from the pressurized fluid source 16 through the pressure-activated valve 54.

[0062] A first fluid resonator device 56a is configured to resonate at a first predetermined frequency in response to fluid flow from the pressurized fluid source 16 through the pressure operated valve 54 to pulse fluid communication between the pressurized fluid source 16 and the suction passage 46 at the first predetermined frequency, and conversely configured to cease resonating in response to fluid flow being blocked from the pressurized fluid source 16 through the pressure operated valve 54. A second fluid resonator device 56b is configured to resonate at a second predetermined frequency in response to fluid flow from the pressurized fluid source 16 through the pressure operated valve 54 to pulse fluid communication between the pressurized fluid source 16 and the suction passage 46 at the second predetermined frequency, and conversely configured to cease resonating in response to fluid flow being blocked from the pressurized fluid source 16 through the pressure operated valve 54.

[0063] The first and second predetermined frequencies may be equal or different (e.g., one relatively high frequency for disrupting occlusive thrombus 2 having a lower viscosity and the other relatively low frequency for disrupting occlusive thrombus 2 having a higher viscosity). The first fluid resonator 56a and the second fluid resonator 56b may be mechanically separated from the pressure-activated valve 54.

[0064] 8A and 8B, one embodiment of a passive pressure oscillation assembly 44a is described. The passive pressure oscillation assembly 44a comprises an inlet channel 60 fluidly coupled to the pressurized fluid source 16 via an inlet port 50, and an outlet channel 62 fluidly coupled to the suction passage 46 via an outlet port 52. The passive pressure oscillation assembly 44a further comprises a valve seal in the form of a seat 64 fluidly coupled to the inlet port 50 via the inlet channel 60, a movable valve element in the form of a valve disc 66 operably connected to the valve seat 64, and an enlarged flow cavity 68 fluidly coupled between the valve seat 64 and the suction passage 46 via the outlet channel 62 and the outlet port 52. The valve disc 66 is configured to be alternately displaced between a closed position (see FIG. 8A), in this case within the valve seat 64, for forming a seal against the valve seat 64, and an open position (see FIG. 8B), in this case outside the valve seat 64, away from the valve seat 64. The passive pressure vibration assembly 44a further includes a restoring spring 70 affixed within the enlarged flow cavity 68 and mechanically coupled to the valve disc 66 for applying a biasing force to the valve disc 66 in a manner that maintains the valve disc 66 in a closed position within the valve seat 64 until the passive pressure vibration assembly 44a is activated to switch from the normal mode to the vibration mode, as will be described in more detail below.

[0065] The valve disc 66 and the valve seat 64 have the same geometric profile (in this case a low trapezoidal cross section) so that when the valve disc 66 is in a closed position within the valve seat 64 (see FIG. 8A ), it forms a seal against the valve seat 64 to prevent the flow of fluid from the pressurized fluid source 16 (in this case fluid introduced into the inlet channel 60 via the inlet port 50) into the enlarged flow cavity 68. When the enlarged flow cavity 68 has a geometric profile larger than that of the valve disc 66 so that when the valve disc 66 is in an open position outside the valve seat 64 and within the enlarged flow cavity 68 (see FIG. 8B ), it allows the fluid from the pressurized fluid source 16 (in this case fluid introduced into the inlet channel 60 via the inlet port 50) to pass into the enlarged flow cavity 68 and further through the outlet channel 62 and into the suction passage 46 via the outlet port 52.

[0066] In response to the occurrence of an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or other anomaly in the aspiration circuit of the system 10, a zero or low flow condition occurs in the aspiration flow passage 46 such that the absolute pressure in the aspiration flow passage 46 drops to a level that creates an actuating negative pressure differential between the inlet port 50 (and thus the inlet channel 60) and the outlet port 52 (and thus the enlarged flow cavity 68), causing the fluid in the inlet channel 60 to exert an opposing force on the valve disc 66 that overcomes the biasing force exerted against the valve disc 66 by the restoring spring 70. As a result, the valve disc 66 is displaced from a closed position (see FIG. 8A) to an open position (see FIG. 8B). The negative pressure differential for actuation of the passive pressure vibration assembly 44a will be determined by the area of ​​the valve disc 66 exposed to the fluid in the inlet channel 60 (the negative pressure differential for actuation decreases in proportion to the exposed area of ​​the valve disc 66) and the spring constant of the restoring spring 70 (the negative pressure differential for action increases in proportion to the spring constant of the restoring spring 70). Thus, by appropriately selecting the exposed area of ​​the valve disc 66 and the spring constant of the restoring spring 70, the negative pressure differential for actuation of the passive pressure vibration assembly 44a can be selected.

[0067] The passive pressure vibration assembly 44a is designed to resonate the passive pressure vibration assembly 44a (i.e., the valve disc 66 is alternately switched (oscillated) between the closed and open positions) when the valve disc 66 is displaced from a closed position to an open position (i.e., the valve is "gapped"). At this point, the passive pressure vibration assembly 44a has been activated to switch from a normal mode to an oscillation mode.

[0068] Specifically, the biasing force exerted by the restoring spring 70 against the valve disc 66, the opposing force exerted against the valve disc 66 by the fluid in the inlet channel 60, and the mass of the valve disc 66 are selected to oscillate the valve disc 66 between the closed and open positions at a predetermined frequency (e.g., in the range of 0.2 Hz to 10 Hz). Preferably, the predetermined frequency is less than the natural frequency of the catheter 12, which is flexible and therefore susceptible to compressive shortening and elongation during pressure cycles. For this reason, the predetermined frequency should not correspond to the natural frequency of the catheter 12, or the catheter 12 may operate in a spring-like axial compression / recovery mode.

[0069] That is, when the valve disc 66 first reaches its fully open position, the opposing force exerted against the valve disc 66 by the fluid flowing from the inlet channel 60, through the valve seat 64, and into the enlarged flow cavity 68 is reduced to a level where the biasing force exerted by the restoring spring 70 overcomes the opposing fluid force on the valve disc 66 and the momentum of the valve disc 66, thereby displacing the valve disc 66 from the open position back to the closed position (see FIG. 8A) within the valve seat 64. At this point, the temporary flow of fluid from the pressurized fluid source 16 into the suction passage 46 (via the inlet port 50, the inlet channel 60, the valve seat 64, the enlarged flow cavity 68, the outlet channel 62, and the outlet port 52) ​​increases the negative pressure differential between the inlet port 50 and the outlet port 52. However, because the valve disc 66 is now in the closed position, thereby preventing the flow of fluid from the pressurized fluid source 16 to the aspiration passageway 46, the negative pressure differential between the inlet port 50 and the outlet port 52 decreases until an actuation negative pressure differential is reached, whereby the opposing force exerted on the valve disc 66 by the fluid in the inlet channel 60 increases to a level that overcomes the biasing force exerted against the valve disc 66 by the restoring spring 70. As a result, the valve disc 66 is displaced from the closed position back to the open position (see FIG. 8B). In this manner, the valve disc 66 is continually displaced back and forth between the closed position (see FIG. 8A) and the open position (see FIG. 8B) until the aspiration conduit 24 of the aspiration catheter 12 is cleared of an obstruction or the abnormality in the aspiration circuit of the system 10 is otherwise resolved.

[0070] The frequency at which the valve disc 66 vibrates depends on the mass of the valve disc 66 (the frequency of vibration decreases as the mass of the valve disc 66 increases), the spring constant of the restoring spring 70 (the frequency of vibration increases as the spring constant of the restoring spring 70 increases), and the length of the valve seat 64 (the frequency of vibration increases as the length of the valve seat 64 decreases), as well as the damping effect of friction between the valve seat 64 and the valve disc 66 and the dynamic force exerted against the valve disc 66 by the fluid flowing from the inlet channel 60, through the valve seat 64 and into the enlarged flow cavity 68 (the frequency of vibration decreases as the damping effect increases). Thus, by appropriately selecting the mass of the valve disc 66, the spring constant of the restoring spring 70, the length of the valve seat 64, and the uncompressed length of the spring 70, the frequency at which the valve disc 66 oscillates (i.e., the resonance of the passive pressure oscillating assembly 44a) can be selected, taking into account the friction between the valve seat 64 and the valve disc 66 and the damping effect that the pressure drop associated with fluid flow from the inlet channel 60 through the valve seat 64 and into the enlarged flow cavity 68 has on the valve disc 66. Such damping effect can itself be adjusted by varying the design sizes and geometries of the inlet port 50, the outlet port 52, the inlet channel 60, and the outlet channel 62.

[0071] In response to removal of an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or otherwise rectifying an anomaly in the aspiration circuit of the system 10, the absolute pressure in the aspiration flow passage 46 increases to a level that creates a blocking negative pressure differential between the inlet port 50 (and thus the inlet channel 60) and the outlet port 52 (and thus the enlarged flow cavity 68), thereby preventing the fluid in the inlet channel 60 from exerting a counterforce on the valve disc 66 that overcomes the biasing force exerted by the restoring spring 70 on the valve disc 66. That is, when the valve disc 66 is in the closed position, the negative pressure differential between the inlet port 50 and the outlet port 52 does not drop below the actuating negative pressure differential because the aspiration flow passage 46 is in a free-flow state. As a result, the biasing force exerted by the restoring spring 70 maintains the valve disc 66 in the closed position. At this point, the passive pressure oscillation assembly 44a has been activated to switch from the oscillation mode back to the normal mode.

[0072] It should be noted that the passive pressure vibration assembly 44a shown in Figures 8A and 8B comprises a pressure actuated valve 54 and a fluid resonator 56 (shown in Figure 5) mechanically coupled to each other in terms of the connection topology. That is, the valve seat 64 and the movable valve disc 66 form the pressure actuated valve 54, whereas the valve disc 66, the enlarged flow cavity 68 and the restoring spring 70 form the fluid resonator 56, where the pressure actuated valve 54 and the fluid resonator 56 are mechanically coupled to each other via the valve disc 66. In this embodiment, because the valve disc 66 forms part of both the pressure actuated valve 54 and the fluid resonator 56, the actuation and deactivation negative pressure differentials and the resonant frequencies must be designed taking each other into account and therefore cannot be optimized independently. However, the resulting design of the passive pressure vibration assembly 44a can be mechanically simple.

[0073] 9A and 9B, another embodiment of a passive pressure vibration assembly 44b is described. Passive pressure vibration assembly 44b is similar to passive pressure vibration assembly 44a shown in Figures 8A and 8B, except that passive pressure vibration assembly 44b includes a longer valve seal relative to the movable valve element with which it interacts, such that its resonant frequency is significantly reduced from that of passive pressure vibration assembly 44a.

[0074] Specifically, the passive pressure oscillation assembly 44b comprises an inlet channel 80 fluidly coupled to the pressurized fluid source 16 via the inlet port 50, and an outlet channel 82 fluidly coupled to the suction flow passage 46 via the outlet port 52. The passive pressure oscillation assembly 44b further comprises a valve seal in the form of a valve cylinder 84 fluidly coupled to the inlet port 50 via the inlet channel 80, a movable valve element in the form of a valve disc 86 operably connected to the valve cylinder 84, and an enlarged flow cavity 88 fluidly coupled between the valve cylinder 84 and the suction flow passage 46 via the outlet channel 62 and the outlet port 52. The valve disc 86 is configured to be alternately displaced between a closed position for sealing within the valve cylinder 84 (see FIG. 9A) and an open position within the enlarged flow cavity 88 (see FIG. 9B). The passive pressure vibration assembly 44b further comprises a restoring spring 90 disposed in a spring cavity 92 between the enlarged flow cavity 88 and the outlet channel 82 and mechanically coupled to the valve disc 86 via a boss 94 affixed to the valve disc 86 for exerting a biasing force against the valve disc 86 to maintain the valve disc 86 in a closed position within the valve cylinder 84 until the passive pressure vibration assembly 44b is activated to switch from the normal mode to the vibration mode.

[0075] The valve disc 86 and the valve cylinder 84 have the same geometric profile (essentially cylindrical in this case) such that when the valve disc 86 is in a closed position within the valve cylinder 84 (see FIG. 9A ), it forms a seal against the valve cylinder 84 to prevent the flow of fluid from the pressurized fluid source 16 (in this case, fluid introduced into the inlet channel 80 via the inlet port 50) into the enlarged flow cavity 88. When the enlarged flow cavity 88 has a geometric profile larger than that of the valve disc 86, such that when the valve disc 86 is in an open position outside the valve cylinder 84 and within the enlarged flow cavity 88 (see FIG. 9B ), it allows the fluid from the pressurized fluid source 16 (in this case, fluid introduced into the inlet channel 80 via the inlet port 50) to pass into the enlarged flow cavity 88 and further through the outlet channel 82 and into the suction passage 46 via the outlet port 52.

[0076] In response to the occurrence of an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or other anomaly in the aspiration circuit of the system 10, a zero or low flow condition occurs in the aspiration flow passage 46 such that the absolute pressure in the aspiration flow passage 46 drops to a level that creates an actuating negative pressure differential between the inlet port 50 (and thus the valve cylinder 84) and the outlet port 52 (and thus the enlarged flow cavity 88), causing the fluid in the inlet channel 80 to exert an opposing force on the valve disc 86 that overcomes the biasing force exerted against the valve disc 86 by the restoring spring 90. As a result, the valve disc 86 is displaced from a closed position (see FIG. 9A) to an open position (see FIG. 9B). The negative pressure differential for actuation of the passive pressure vibration assembly 44b will be based on the area of ​​the valve disc 86 exposed to the fluid in the valve cylinder 84 (the negative pressure differential for actuation decreases in proportion to the exposed area of ​​the valve disc 86) and the spring constant of the restoring spring 90 (the negative pressure differential for action increases in proportion to the spring constant of the restoring spring 90). Thus, by appropriately selecting the exposed area of ​​the valve disc 86 and the spring constant of the restoring spring 90, the negative pressure differential for actuation of the passive pressure vibration assembly 44b can be selected.

[0077] The passive pressure vibration assembly 44b is designed to resonate the passive pressure vibration assembly 44b (i.e., the valve disc 86 is alternately switched (oscillated) between the closed and open positions) when the valve disc 86 is displaced from a closed position to an open position (i.e., the valve is "gapped"). At this point, the passive pressure vibration assembly 44b has been activated to switch from a normal mode to an oscillation mode.

[0078] Specifically, the biasing force exerted against the valve disc 86 by the restoring spring 90, the opposing force exerted by the fluid within the valve cylinder 84, and the mass of the valve disc 86 are selected to cause the valve disc 86 to oscillate between the closed and open positions at a predetermined frequency (e.g., in the range of 0.2 Hz to 10 Hz).

[0079] That is, as the valve disc 86 reaches its full open position, the opposing force exerted against the valve disc 86 by the fluid flowing from the inlet channel 80 through the valve cylinder 84 and into the enlarged flow cavity 88 decreases to a level where the biasing force exerted by the restoring spring 90 overcomes the opposing fluid force on the valve disc 86 and the momentum of the valve disc 86, thereby displacing the valve disc 86 from the open position back to the closed position (see FIG. 9A ) within the valve cylinder 84. At this point, the temporary flow of fluid from the pressurized fluid source 16 into the suction passage 46 (via the inlet port 50, the inlet channel 80, the valve cylinder 84, the enlarged flow cavity 88, the spring cavity 92, the outlet channel 82, and the outlet port 52) ​​increases the negative pressure differential between the inlet port 50 and the outlet port 52. However, because the valve disc 86 is now in the closed position, thereby preventing the flow of fluid from the pressurized fluid source 16 to the aspiration passageway 46, the negative pressure differential between the inlet port 50 and the outlet port 52 decreases until an actuation negative pressure differential is reached, causing the opposing force exerted on the valve disc 86 by the fluid in the valve cylinder 84 to increase to a level that overcomes the biasing force exerted against the valve disc 86 by the restoring spring 90. As a result, the valve disc 86 is again displaced from the closed position to the open position (see FIG. 9B). In this manner, the valve disc 86 is continually displaced alternately between the closed position (see FIG. 9A) and the open position (see FIG. 9B) until the aspiration catheter 12 is cleared of an obstruction or the abnormality in the aspiration circuit of the system 10 is otherwise resolved.

[0080] The frequency at which the valve disc 86 vibrates depends on the mass of the valve disc 86 (as the mass of the valve disc 86 increases, the frequency of vibration decreases), the spring constant of the restoring spring 90 (as the spring constant of the restoring spring 90 increases, the frequency of vibration increases), and the length of the valve cylinder 84 (as the length of the valve seat 64 decreases, the frequency of vibration increases), as well as the damping effect of friction between the valve cylinder 84 and the valve disc 86 and the dynamic force exerted on the valve disc 86 by the fluid flowing from the inlet channel 60 through the valve cylinder 84 and into the enlarged flow cavity 88 (as the damping effect increases, the frequency of vibration decreases). Thus, by appropriately selecting the mass of the valve disc 86, the spring constant of the restoring spring 90, the length of the valve cylinder 84, and the pre-compressed length of the spring 90, the frequency at which the valve disc 86 oscillates (i.e., the resonance of the passive pressure oscillating assembly 44b) can be selected, taking into account the friction between the valve cylinder 84 and the valve disc 86 and the damping effect that the fluid flow from the inlet channel 80 through the valve cylinder 84 and into the enlarged flow cavity 88 has on the valve disc 86. Such damping effect can itself be adjusted by varying the design sizes and geometries of the inlet port 50, the outlet port 52, the inlet channel 80, and the outlet channel 82.

[0081] In response to removal of an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or otherwise rectifying an anomaly in the aspiration circuit of the system 10, the absolute pressure in the aspiration flow passage 46 increases to a level that creates an actuating negative pressure differential between the inlet port 50 (and thus the valve cylinder 84) and the outlet port 52 (and thus the enlarged flow cavity 88), thereby preventing the fluid in the inlet channel 80 from exerting a counter force on the valve disc 86 that overcomes the biasing force exerted by the restoring spring 90 on the valve disc 86. That is, when the movable valve cylinder 86 is in the closed position, the negative pressure differential between the inlet port 50 and the outlet port 52 does not drop below the actuating negative pressure differential because the aspiration flow passage 46 is in a free-flowing state. As a result, the biasing force exerted by the restoring spring 90 maintains the valve disc 86 in the closed position. At this point, the passive pressure oscillation assembly 44b has been activated to switch from the oscillation mode back to the normal mode.

[0082] It should be noted that the passive pressure vibration assembly 44b shown in Figures 9A and 9B comprises a pressure actuated valve 54 and a fluid resonator 56 (shown in Figure 5) mechanically coupled to each other in terms of the connection topology. That is, the valve cylinder 84 and the valve disc 86 form the pressure actuated valve 54, whereas the valve disc 86, the enlarged flow cavity 88, and the restoring spring 90 form the fluid resonator 56, where the pressure actuated valve 54 and the fluid resonator 56 are mechanically coupled to each other via the valve disc 86. In this embodiment, because the valve disc 86 forms part of both the pressure actuated valve 54 and the fluid resonator 56, the actuation and deactivation negative pressure differentials and the resonant frequency must be designed taking each other into account and therefore cannot be optimized independently. However, the resulting design of the passive pressure vibration assembly 44b can be mechanically simple.

[0083] 10A-10D, another embodiment of a passive pressure oscillation assembly 44c will now be described. The passive pressure oscillation assembly 44c is similar to the passive pressure oscillation assembly 44a shown in FIGURES 6A and 6B, except that the passive pressure oscillation assembly 44c includes an additional oscillation enhancement mechanism that ensures that the passive pressure oscillation assembly 44c remains in oscillation mode as long as an obstruction in the aspiration conduit 24 of the aspiration catheter 12 remains or an abnormality in the aspiration circuit of the system 10 is otherwise cleared.

[0084] The passive pressure oscillation assembly 44c comprises an inlet channel 100 fluidly coupled to the pressurized fluid source 16 via an inlet port 50 and an outlet channel 102 fluidly coupled to the suction flow passage 46 via an outlet port 52. The passive pressure oscillation assembly 44c further comprises a valve seal in the form of a seat 104, a movable valve element in the form of a valve disc 106 operably coupled to the valve seat 104, and an enlarged flow cavity 108 fluidly coupling the valve seat 104 to the suction flow passage 46 via the outlet channel 102 and the outlet port 52. The valve disc 106 is configured to be displaced alternately between a closed position (see FIGS. 10A and 10D), in this case within the valve seat 104, forming a seal against the valve seat 104, and an open position (see FIGS. 10B and 10C), in this case outside the valve seat 104, away from the valve seat 104. The passive pressure vibration assembly 44c further includes a restoring spring 110 disposed within the enlarged flow cavity 108 and mechanically coupled to the valve disc 106 for exerting a biasing force against the valve disc 106 in a manner that maintains the valve disc 106 in a closed position within the valve seat 104 until the passive pressure vibration assembly 44c is activated to switch from the normal mode to the vibration mode.

[0085] The passive pressure oscillation assembly 44c further comprises a plunger cavity 114, a plunger head 116 slidably disposed within the plunger cavity 114, a reduced profile central cavity 118, a plunger stop 120 disposed between the plunger cavity 114 and the reduced profile central cavity 118, and another restoring spring 122 mechanically coupled to the plunger head 116 via a boss 124 affixed to the plunger head 116 for exerting a biasing force on the plunger head 116 to maintain the plunger head 116 away from the plunger stop 120. In the embodiment shown, the profile of the reduced profile central cavity 118 is smaller than the profile of the plunger cavity 114, such that the plunger stop 120 is formed by a wall of the plunger cavity 114 adjacent the reduced profile central cavity 118. The plunger head 116 has a fluid pressure equalization channel 126 extending therethrough. The plunger cavity 114 is fluidly coupled between the valve seat 104 and the plunger cavity 114 such that the valve seat 104 is always in fluid communication with the inlet port 50 via the fluid pressure equalization channel 126 extending through the plunger head 116 such that fluid from the pressurized fluid source 16 can flow into the reduced profile central cavity 118. The fluid pressure equalization channel 126 extending through the plunger head 116 thus functions to equalize pressure between the pressurized fluid source 16 and the reduced profile central cavity 118.

[0086] The valve disc 106 and the valve seat 104 have the same geometric profile (in this case, a low trapezoidal shaped cross section) so that when the valve disc 106 is in a closed position within the valve seat 104 (see Figures 10A and 10D), it prevents the flow of fluid from the pressurized fluid source 16 (in this case, fluid introduced from the inlet channel 100 via the inlet port 50, through the fluid pressure equalization channel 126 of the plunger head 116, and into the reduced profile central cavity 118) into the enlarged flow cavity 108. The enlarged flow cavity 108 has a geometric profile larger than that of the valve disc 106, such that when the valve disc 106 is in an open position (see FIGS. 10B and 10C) outside the valve seat 104 and inside the enlarged flow cavity 108, it allows the flow of fluid from the pressurized fluid source 16 (in this case, fluid introduced into the plunger cavity 114 from the inlet port 50 and the inlet channel 100 via the fluid pressure equalization channel 126) into the enlarged flow cavity 108, through the outlet channel 102, and into the suction flow passage 46 via the outlet port 52. The plunger head 116 and plunger cavity 114 have the same geometric profile (in this case, essentially cylindrical), and fluid from the pressurized fluid source 16 can enter the reduced profile central cavity 118 only via the fluid pressure equalization channel 126 of the plunger head 116.

[0087] In response to an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or other anomaly occurring in the aspiration circuit of the system 10, a zero or low flow condition occurs in the aspiration flow passage 46 such that the absolute pressure in the aspiration flow passage 46 drops to a level that creates an actuating negative pressure differential between the inlet port 50 (and thus the reduced profile central cavity 118) and the outlet port 52 (and thus the enlarged flow cavity 108), causing the fluid in the plunger cavity 114 and thus the fluid in the reduced profile central cavity 118 to exert an opposing force on the valve disc 106 that overcomes the biasing force exerted against the valve disc 106 by the restoring spring 110. As a result, the valve disc 106 is displaced from a closed position (see FIG. 10A) to an open position (see FIG. 10B). The negative pressure differential for actuation of the passive pressure vibration assembly 44c will be based on the area of ​​the valve disc 106 exposed to the fluid in the inlet channel 100 (the negative pressure differential for actuation decreases in proportion to the exposed area of ​​the valve disc 106) and the spring constant of the restoring spring 110 (the negative pressure differential for action increases in proportion to the spring constant of the restoring spring 110). Thus, by appropriately selecting the exposed area of ​​the valve disc 106 and the spring constant of the restoring spring 110, the negative pressure differential for actuation of the passive pressure vibration assembly 44c can be selected.

[0088] The passive pressure vibration assembly 44c is designed to resonate the passive pressure vibration assembly 44c (i.e., the valve disc 106 is alternately switched (oscillated) between the closed and open positions) when the valve disc 106 is displaced from a closed position to an open position (i.e., the valve is "gapped"). At this point, the passive pressure vibration assembly 44c has been activated to switch from a normal mode to an oscillation mode.

[0089] Specifically, the biasing force exerted against the valve disc 106 by the restoring spring 110, the opposing force exerted against the valve disc 106 by the fluid in the reduced profile central cavity 118, and the mass of the valve disc 106 are selected to oscillate the valve disc 106 between the closed and open positions at a predetermined frequency. Additionally, the dynamic displacement of the plunger head 116 within the plunger cavity 114 ensures that the valve disc 106 does not stick in the open position as fluid flowing from the reduced profile central cavity 118 into the enlarged flow cavity 108 exerts a force on the valve disc 106.

[0090] Specifically, when the valve disc 106 is displaced from the closed position to the open position (see FIG. 10C ), fluid flows from the plunger cavity 114 in front of the plunger head 116, through the reduced-profile central cavity 118, through the valve seat 104, and into the enlarged flow cavity 108, thereby displacing the plunger head 116 within the plunger cavity 114 toward the reduced-profile central cavity 118 until the plunger head 116 abuts against the plunger stop 120, allowing additional fluid to flow from the pressurized fluid source 16, through the inlet port 50 and the inlet channel 100, and into the plunger cavity 114 behind the plunger head 116. When the plunger head 116 abuts the plunger stop 120, fluid flow from the reduced profile central cavity 118, through the valve seat 104, and into the enlarged flow cavity 108 is significantly reduced and limited to flow only through the fluid pressure equalization channel 126 through the plunger head 116. Thus, the opposing force exerted against the valve disc 106 by the fluid flowing from the reduced profile central cavity 118, through the valve seat 104, and into the enlarged flow cavity 108 is reduced to a level where the biasing force exerted by the restoring spring 110 overcomes the opposing fluid forces exerted on the valve disc 106 and the momentum of the valve disc 106. As a result, the valve disc 106 is displaced from the open position back to the closed position (see FIG. 10D) within the valve seat 104. Fluid pressure between the reduced profile central cavity 118 and the plunger cavity 114 is equalized via fluid pressure equalization channel 126 through the plunger head 116, thereby reducing the opposing force exerted on the plunger head 116 by the fluid in the plunger cavity 114 to a level where the biasing force exerted by the restoring spring 122 overcomes the opposing fluid force exerted on the plunger head 116 and the momentum of the plunger head 116. As a result, the plunger head 116 is displaced away from the plunger stop 120 within the plunger cavity 114 and returns to its neutral position (see FIG. 10A).In this way, unlike the passive pressure vibration assembly 44a shown in Figures 8A-8B and also the passive pressure vibration assembly 44a shown in Figures 9A-9B, which allows fluid to flow unimpeded past the valve seat, which may under certain circumstances maintain the valve disc open, thereby preventing oscillation of the valve seat between the closed and open positions, the action of the plunger head 116 in the plunger cavity 114 prevents the valve disc 106 from "stuck" in the open position by significantly reducing the flow of fluid through the valve seat 104 that may otherwise prevent the valve disc 106 from returning to its closed position within the valve seat 104.

[0091] The frequency at which the valve disc 106 vibrates depends on the frequency at which the plunger head 116 vibrates within the plunger cavity 114, which in turn depends on the mass of the plunger head 116 (the frequency of vibration decreases as the mass of the plunger head 116 increases), the spring constant of the restoring spring 122 (the frequency of vibration increases as the spring constant of the restoring spring 122 increases), the diameter of the equalization channel 126, and the damping effect of friction between the plunger cavity 114 and the plunger head 116, as well as the dynamic forces of the fluid within the plunger cavity 114, including the fluid flowing through the fluid pressure equalization channel 126 of the plunger head 116 during equalization of the fluid pressure within the plunger cavity 114 (the frequency of vibration decreases as the damping effect increases). Thus, by appropriately selecting the mass of the plunger head 116 and the spring constant of the restoring spring 122, as well as the diameter of the equalization channel 126, the frequency at which the valve disc 106 vibrates (i.e., the resonance of the passive pressure oscillation assembly 44c) can be selected, taking into account the damping effect that friction between the plunger cavity 114 and the plunger head 116 and the dynamics of the fluid in the reduced profile central cavity 118 have on the plunger head 116. Such damping effect can itself be adjusted by varying the design sizes of the inlet port 50, the outlet port 52, the inlet channel 100, and the outlet channel 102.

[0092] In response to removal of an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or otherwise elimination of an anomaly in the aspiration circuit of the system 10, the absolute pressure in the aspiration flow passage 46 increases to a level that creates a stopping negative pressure differential between the inlet port 50 (and thus the inlet channel 100) and the outlet port 52 (and thus the enlarged flow cavity 108), thereby preventing the fluid in the reduced profile central cavity 118 from exerting a counter force on the valve disc 106 that overcomes the biasing force exerted by the spring 100 on the valve disc 106. That is, when the valve disc 106 is in the closed position, the negative pressure differential between the inlet port 50 and the outlet port 52 does not drop below the actuating negative pressure differential because the aspiration flow passage 46 is in a free flow state. As a result, the biasing force exerted by the restoring spring 110 maintains the valve disc 106 in the closed position. At this point, the passive pressure oscillation assembly 44c has been activated to switch from the oscillation mode to the normal mode.

[0093] Although the movable valve element in passive pressure vibration assemblies 44a-44c shown in Figures 8-10 has been described as a valve disk, it should be appreciated that the movable valve element may have any suitable form that can be operatively coupled to a corresponding valve seal to alternately allow and prevent fluid from the pressurized fluid source 16 to flow therethrough. For example, with reference to Figures 11A and 11B, an alternative embodiment of passive pressure vibration assembly 44d is similar to passive pressure vibration assembly 44a of Figures 8A-8B, except that the movable valve element takes the form of a ball.

[0094] Specifically, the passive pressure oscillation assembly 44d comprises an inlet channel 130 fluidly coupled to the pressurized fluid source 16 via an inlet port 50, and an outlet channel 132 fluidly coupled to the suction flow passage 46 via an outlet port 52. The passive pressure oscillation assembly 44d further comprises a valve seal in the form of a seat 134 fluidly coupled to the inlet port 50 via the inlet channel 130, a movable valve element in the form of a valve ball 136 operably coupled to the valve seat 134, and an enlarged flow cavity 138 fluidly coupled between the valve seat 134 and the suction flow passage 46 via the outlet channel 132 and the outlet port 52. The valve ball 136 is configured to be alternately displaced between a closed position (see FIG. 11A) for forming a seal against the valve seat 134, and an open position (see FIG. 11B) away from, and in this case exterior to, the valve seat 64. The passive pressure vibration assembly 44d further includes a spring 140 affixed within the enlarged flow cavity 138 and mechanically coupled to the valve ball 136 for applying a biasing force to the valve ball 136 in a manner that maintains the valve ball 136 in a closed position against the valve seat 134 until the passive pressure vibration assembly 44d is activated to switch from the normal mode to the vibration mode, as will be described in more detail below.

[0095] The surface of the valve seat 134 that contacts the valve ball 136 preferably has a spherical profile so that when the valve ball 136 is in a closed position relative to the valve seat 134 (see FIG. 11A ), it forms a seal against the valve seat 134 to prevent the flow of fluid from the pressurized fluid source 16 (in this case, fluid introduced into the inlet channel 130 via the inlet port 50) into the enlarged flow cavity 138. The enlarged flow cavity 138 has a geometric profile that is larger than that of the valve ball 136 so that when the valve ball 136 is in an open position (see FIG. 11B ) away from the valve seat 134 and into the enlarged flow cavity 138, it allows the flow of fluid from the pressurized fluid source 16 (in this case, fluid introduced into the inlet channel 130 via the inlet port 50) into the enlarged flow cavity 138, through the outlet channel 132 and into the suction passage 46 via the outlet port 52.

[0096] In response to the occurrence of an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or other anomaly in the aspiration circuit of the system 10, a zero or low flow condition occurs in the aspiration flow path 46 such that the absolute pressure in the aspiration flow path 46 drops to a level that creates an actuating negative pressure differential between the inlet port 50 (and thus the inlet channel 130) and the outlet port 52 (and thus the enlarged flow cavity 138), causing the fluid in the inlet channel 130 to exert an opposing force against the valve ball 136 that overcomes the biasing force exerted against the valve ball 136 by the spring 140. As a result, the valve ball 136 is displaced from a closed position (see FIG. 11A) to an open position (see FIG. 11B). The negative pressure differential for actuation of the passive pressure vibration assembly 44d will be based on the area of ​​the valve ball 136 exposed to the fluid in the inlet channel 130 (the negative pressure differential for actuation decreases in proportion to the exposed area of ​​the valve ball 136) and the spring constant of the spring 140 (the negative pressure differential for action increases in proportion to the spring constant of the spring 140). Thus, by appropriately selecting the exposed area of ​​the valve ball 136 and the spring constant of the spring 140, the negative pressure differential for actuation of the passive pressure vibration assembly 44d can be selected.

[0097] The passive pressure vibration assembly 44d is designed to resonate the passive pressure vibration assembly 44d (i.e., the valve ball 136 is toggled (oscillated) between the closed and open positions) when the valve ball 136 is displaced from a closed position to an open position (i.e., the valve is "gapped"). At this point, the passive pressure vibration assembly 44d has been activated to switch from a normal mode to an oscillation mode.

[0098] Specifically, the biasing force exerted by spring 140 against valve ball 136, the opposing force exerted against valve ball 136 by the fluid in inlet channel 130, and the mass of valve ball 136 are selected to cause valve ball 136 to oscillate between closed and open positions at a predetermined frequency (e.g., 0.2 Hz to 10 Hz).

[0099] That is, when the valve ball 136 first reaches the fully open position, the opposing force exerted against the valve ball 136 by the fluid flowing from the inlet channel 60, through the valve seat 134, and into the enlarged flow cavity 138, decreases to a level where the biasing force exerted by the spring 140 overcomes the opposing fluid force on the valve ball 136 and the momentum of the valve ball 136, thereby displacing the valve ball 136 from the open position back to the closed position (see FIG. 11A ) within the valve seat 134. At this point, the temporary flow of fluid from the pressurized fluid source 16 into the suction flow passage 46 (via the inlet port 50, the inlet channel 130, the valve seat 134, the enlarged flow cavity 138, the outlet channel 132, and the outlet port 52) ​​increases the negative pressure differential between the inlet port 50 and the outlet port 52. However, because the valve ball 136 is now in the closed position, thereby preventing the flow of fluid from the pressurized fluid source 16 to the aspiration flow passage 46, the negative pressure differential between the inlet port 50 and the outlet port 52 decreases until an actuation negative pressure differential is reached, whereby the opposing force exerted on the valve ball 136 by the fluid in the inlet channel 60 increases to a level that overcomes the biasing force exerted against the valve ball 136 by the spring 140. As a result, the valve ball 136 is displaced from the closed position back to the open position (see FIG. 11B). In this manner, the valve ball 136 is continually displaced back and forth between the closed position (see FIG. 11A) and the open position (see FIG. 11B) until the aspiration conduit 24 of the aspiration catheter 12 is cleared of an obstruction or otherwise the anomaly in the aspiration circuit of the system 10 is corrected.

[0100] The frequency at which the valve ball 136 vibrates depends on the mass of the valve ball 136 (the frequency of vibration decreases as the mass of the valve ball 136 increases), the spring constant of the spring 140 (the frequency of vibration increases as the spring constant of the spring 140 increases), and the damping effect of the dynamic forces on the valve ball 136 of the fluid flowing from the inlet channel 130 through the valve seat 134 and into the enlarged flow cavity 138 (the frequency of vibration decreases as the damping effect increases). Thus, by appropriately selecting the mass of the valve ball 136, the spring constant of the spring 140, the length of the valve seat 134, and the pre-compression length of the spring 140, taking into account the damping effect that the fluid flowing from the inlet channel 130 through the valve seat 134 and into the enlarged flow cavity 138 has on the valve ball 136, the frequency at which the valve ball 136 vibrates (i.e., the resonance of the passive pressure vibration assembly 44a) can be selected. The attenuation effect itself can be tailored by varying the design sizes and geometries of the inlet ports 50, outlet ports 52, inlet channels 130, and outlet channels 132.

[0101] In response to removal of an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or otherwise rectifying an anomaly in the aspiration circuit of the system 10, the absolute pressure in the aspiration flow passage 46 increases to a level that creates a stopping negative pressure differential between the inlet port 50 (and thus the inlet channel 130) and the outlet port 52 (and thus the enlarged flow cavity 138), thereby preventing the fluid in the inlet channel 130 from exerting a counterforce on the valve ball 136 that overcomes the biasing force exerted by the spring 140 on the valve ball 136. That is, when the valve ball 136 is in the closed position, the negative pressure differential between the inlet port 50 and the outlet port 52 does not drop below the actuating negative pressure differential because the aspiration flow passage 46 is in a free-flow state. As a result, the biasing force exerted by the spring 140 maintains the valve ball 136 in the closed position. At this point, the passive pressure oscillation assembly 44d has been activated to switch from the oscillation mode back to the normal mode.

[0102] It should be noted that the passive pressure vibration assembly 44d shown in Figures 11A and 11B comprises a pressure actuated valve 54 and a fluid resonator 56 (shown in Figure 5) mechanically coupled to each other in terms of the connection topology. That is, the valve seat 134 and the movable valve ball 136 form the pressure actuated valve 54, whereas the valve ball 136, the enlarged flow cavity 138 and the spring 140 form the fluid resonator 56, where the pressure actuated valve 54 and the fluid resonator 56 are mechanically coupled to each other via the valve ball 136. In this embodiment, because the valve ball 136 forms part of both the pressure actuated valve 54 and the fluid resonator 56, the actuation and deactivation negative pressure differentials and the resonant frequency must be designed taking each other into account and therefore cannot be optimized independently. However, the resulting design of the passive pressure vibration assembly 44d can be mechanically simple.

[0103] 12, one method 150 of operating the aspiration system 10 to aspirate vascular obstruction material 2 from the patient's vasculature 1 is described. The method 150 includes introducing the aspiration catheter 12 into the patient's vasculature 1 until the distal end 30 of the catheter body 22 is adjacent the vascular obstruction material 2 (step 152). The suction source 14 is then operated to create an aspiration flow path 46 between the aspiration catheter 12 and the suction source 14 for the purpose of actively aspirating the vascular obstruction material 2, while the passive pressure oscillation assembly 44 is operated in a normal mode to prevent fluid communication between the pressurized fluid source 16 and the aspiration flow path 46 (step 154). Thus, at this point, aspiration of the vascular obstruction material 2 is performed as efficiently as possible.

[0104] Optionally, the passive pressure oscillation assembly 44 is activated in response to the active suction of the vascular obstruction material 2 (e.g., when the absolute pressure in the aspiration channel 46 drops to a level that creates a first actuating negative pressure difference of less than −50 kPa between the pressurized fluid source 44 and the aspiration channel 46), to switch from the normal mode to the first oscillation mode, such that the fluid communication between the pressurized fluid source 16 and the aspiration channel 46 is pulsed at an appropriate amplitude and frequency (e.g., high frequency, low amplitude) to enhance the active suction of the vascular obstruction material 2 (step 156). Pulsing the fluid communication between the pressurized fluid source 16 and the aspiration channel 46 at a high frequency and low amplitude can minimize disturbance to the aspiration channel 46, such that the active suction of the vascular obstruction material 2 can be as efficient as possible.

[0105] Next, if an obstruction occurs in the aspiration flow path 24 of the aspiration catheter 12 (e.g., if the absolute pressure in the aspiration flow path 46 drops to a level that creates a second actuation negative pressure difference of less than −55 kPa between the pressurized fluid source 44 and the aspiration flow path 46) (step 158), the passive pressure oscillation assembly 44 is activated to switch from a normal mode (or, optionally, a first oscillation mode) to a (second) oscillation mode, such that the fluid communication between the pressurized fluid source 16 and the aspiration flow path 46 is pulsed at an appropriate amplitude and frequency (e.g., low frequency, high amplitude) to enhance the removal of the obstruction (step 160). Optionally, the fluid communication between the pressurized fluid source 16 and the aspiration flow path 46 can be pulsed at different frequencies simultaneously. If no obstruction occurs in the suction conduit 24 of the suction catheter 12 (e.g., the absolute pressure in the suction flow path 46 does not drop to a level that creates a second operating negative pressure differential of less than -55 kPa between the pressurized fluid source 44 and the suction flow path 46) (step 158), the passive pressure oscillation assembly 44 remains in the normal mode (or, optionally, the first oscillation mode) until the vascular obstruction 2 is completely aspirated.

[0106] If an obstruction has occurred in the aspiration conduit 24 of the aspiration catheter 12 and the obstruction is removed, or if the abnormality in the aspiration circuit of the aspiration system 10 is otherwise resolved (e.g., if the absolute pressure in the aspiration flow path 46 increases to a level that creates a deactivation negative pressure differential between the pressurized fluid source 44 and the aspiration flow path 46, preferably between 10 kPa and 25 kPa, which is greater than the activation negative pressure differential) (step 162), the passive pressure oscillation assembly 44 is activated to switch from the oscillation mode to the normal mode, so that fluid communication between the pressurized fluid source 16 and the aspiration flow path 46 is again prevented, and the aspiration procedure continues (step 164). If an obstruction occurs in the suction conduit 24 of the suction catheter 12 and is not removed, or if the abnormality in the suction circuit of the suction system 10 is not otherwise resolved (e.g., if the absolute pressure in the suction flow path 46 does not increase to a level that creates a negative pressure difference for shutdown between the pressurized fluid source 44 and the suction flow path 46, preferably between 10 kPa and 25 kPa, which is greater than the negative pressure difference for activation), the passive pressure oscillation assembly 44 will remain in the (second) oscillation mode until the vascular obstruction 2 is removed or the abnormality in the suction circuit of the suction system 10 is otherwise resolved.

[0107] While the stopping pressure differential of the passive pressure vibration assembly 44 and its variations has been described as being less than the operating negative pressure differential resulting from a free-flow condition in the suction passage 46, the stopping pressure differential of one advantageous embodiment of the passive pressure vibration assembly 244 exceeds the operating negative pressure differential resulting from a free-flow condition in the suction passage 46, as shown in Figures 13A-13E and 14.

[0108] Like the passive pressure oscillation assembly 44, the passive pressure oscillation assembly 244 is configured to dynamically fill (i.e., rapidly change vacuum levels) the aspiration conduit 24 of the aspiration catheter 12 (shown in FIG. 1 ), and in particular is configured to periodically fill the aspiration conduit 24 only during zero or low flow conditions. Like the passive pressure oscillation assembly 44, the passive pressure oscillation assembly 44 achieves this without user input or the use of electronic sensors, and can be very compact such that it can fit within the manifold 20 without adding bulk, and can be deactivated simply by blocking the relief inlet 40.

[0109] Similar to the passive pressure oscillation assembly 44, the passive pressure oscillation assembly 244 is configured to operate between a normal mode which prevents fluid communication along the relief path 48 between the pressurized fluid source 16 and the aspiration flow path 46, where the absolute pressure in the aspiration flow path 46 remains relatively constant and is acted upon only by the suction source 14, and an oscillation mode which pulses fluid communication along the relief path 48 between the pressurized fluid source 16 and the aspiration flow path 46, where the absolute pressure in the aspiration flow path 46 oscillates within a preset frequency range. The passive pressure oscillation assembly 244 is configured to operate to switch from the normal mode to the oscillation mode in response to an obstruction in the aspiration conduit 24 of the aspiration catheter 12 or a flow anomaly in the aspiration conduit of the system 10, and conversely to switch from the oscillation mode to the normal mode in response to the removal or clearance of the obstruction from the aspiration conduit 24 of the aspiration catheter 12 or the resolution of the flow anomaly in the aspiration circuit of the system 10. In the illustrated embodiment, pulsing of fluid communication between the pressurized fluid source 16 and the aspiration fluid line 46 causes pressure pulses to propagate through the aspiration conduit 24 of the aspiration catheter 12 at one or more preset frequencies, and further at two predetermined frequencies as described below. Simultaneously, pulsing of fluid communication between the pressurized fluid source 16 and the aspiration fluid line 46 causes a backflow of fluid to propagate through the aspiration conduit 24 of the aspiration catheter 12.

[0110] Unlike the passive pressure oscillation assembly 44, the stopping pressure difference of the passive pressure oscillation assembly 244 is higher than the actuating negative pressure difference resulting from a free-flow condition in the aspiration flow path 46, so that the stopping negative pressure difference can be designed to be much larger than the actuating negative pressure difference, ultimately increasing the vibration strength for clearing obstructions from the aspiration conduit 24 of the aspiration catheter 12. For example, while the passive pressure oscillation assembly 44 and its variations described above may have a stopping negative pressure difference that is 10 kPa to 25 kPa larger than the actuating negative pressure difference, the passive pressure oscillation assembly 244 may have a stopping negative pressure difference that is 40 kPa to 90 kPa larger than the actuating negative pressure difference.

[0111] The passive pressure oscillation assembly 244 is also configured to operate in a mixed frequency mode. In particular, the passive pressure oscillation assembly 244 may be operated in an oscillation mode that pulses the fluid communication between the pressurized fluid source 16 and the aspiration channel 46 at a first frequency (e.g., in the range of 0.2 Hz to 10 Hz) and a second frequency (e.g., in the range of 100 Hz to 400 Hz) different from the first frequency simultaneously. This allows the low frequency oscillation mode of the passive pressure oscillation assembly 244 to exert a relatively constant large force on the thrombus 2 in the aspiration conduit 24 of the aspiration catheter 12, while the high frequency oscillation mode of the passive pressure oscillation assembly may exert a fluctuating small force on the thrombus 2 to reduce friction between the thrombus 2 and the aspiration conduit 24.

[0112] The passive pressure oscillation assembly 244 includes a plunger cavity 254 having a plurality of cavity ports 256 (including an inlet port 256a, an outlet port 256b, bypass ports 256c, 256d, a pressure tap port 256e, a suction shutoff port 256f, and a pressure equalization port 256g) all spaced apart along a length of the plunger cavity 254, a plunger assembly 258 slidably disposed within the plunger cavity 254, and a pressure equalizer 256a configured to apply a biasing force to the plunger assembly 254. the plunger cavity 254 includes a nozzle 260, a plurality of channels including an inlet channel 262, an outlet channel 264, a bypass channel 266, a pressure tap channel 268, a suction shutoff channel 270 and a pressure equalization channel 272, all of which are in conditional fluid communication with the plunger cavity 254 via a plurality of ports 256; a fluid-actuated suction shutoff valve 274 disposed in the suction flow passage 46 between the suction source 14 and the pressure tap channel 268; and a fluid resonator 276 disposed in the outlet channel 262.

[0113] The plunger assembly 258 includes a rod 278, a first plunger head 280 secured to the rod 278, and a second plunger head 282 secured to the rod 278 and spaced apart from the first plunger head 280, thereby defining a front plunger cavity area 284 forward of the first plunger head 280, a central plunger cavity area 286 between the first and second plunger heads 280 and 282, and a rear plunger cavity area 288 rearward of the second plunger head 282. As described in more detail below, when the passive pressure oscillation assembly 244 is operating in an oscillation mode, the plunger assembly 258 is configured to displace within the plunger cavity 254 between open and closed positions to generate low frequency fluid pulses within the aspiration passageway 46. Thus, the vibration mode of the passive pressure vibration assembly 244 can pulse fluid communication between the pressurized fluid source 16 and the suction passage 46 at a first frequency. For reasons described in more detail below, the outer diameter of the second plunger head 282 is larger than the outer diameter of the first plunger head 280. The plunger cavity 254 has a first portion 290 having a first diameter for accommodating the first plunger head 280 and a second portion 292 having a second diameter larger than the first diameter for accommodating the second plunger head 282.

[0114] The inlet channel 262 is in fluid communication between the pressurized fluid source 16 and the front plunger cavity region 284 (via the inlet port 256a of the plunger cavity 254). The outlet channel 264 is in conditional fluid communication between the center plunger cavity region 286 and the aspiration passageway 46 (via the outlet cavity port 256b of the plunger cavity 254). The bypass channel 266 is in conditional fluid communication between the front plunger cavity region 284 (via the first bypass port 256c of the plunger cavity 254) and the center plunger cavity region 286 (via the second bypass port 256d of the plunger cavity 254). The pressure tap channel 268 is in fluid communication between the aspiration passageway 46 and the rear plunger cavity region 288 (via the pressure tap port 256e of the plunger cavity 254). The suction shutoff channel 270 is in conditional fluid communication between the center plunger cavity region 286 and the fluid-actuated valve 274 (via suction shutoff port 256f of the plunger cavity 254) and is in conditional fluid communication between the rear plunger cavity region 288 and the fluid-actuated valve 274 (via suction shutoff port 256f of the plunger cavity 254). The pressure equalization channel 272 is in conditional fluid communication between the suction passage 46 and the center plunger cavity region 286 (via pressure equalization port 256g of the plunger cavity 254).

[0115] When the passive pressure oscillation assembly 244 is operating in an oscillation mode, the fluid resonator 276 is configured to resonate in response to fluid flowing through the outlet channel 264, thereby generating high frequency fluid pulses in the aspiration flow passage 46. The oscillation mode of the passive pressure oscillation assembly 244 can thus pulse the fluid communication between the pressurized fluid source 16 and the aspiration flow passage 46 at a first frequency simultaneously and at a second frequency different from the first frequency. In the illustrated embodiment, the fluid resonator 276 takes the form of a paddle wheel that rotates in response to fluid flow through the outlet channel 264, although other types of fluid resonators are contemplated.

[0116] When the passive pressure oscillation assembly 244 is operating in a normal mode, the fluid actuated valve 274 is configured to open in response to a lack of fluid flow through the aspiration shutoff channel 270, thereby allowing fluid communication between the suction source 14 and the aspiration flow path 46. In contrast, when the passive pressure oscillation assembly 244 is operating in an oscillation mode, the fluid actuated valve 274 is configured to close in response to a presence of fluid flow through the aspiration shutoff channel 270, thereby preventing fluid communication between the suction source 14 and the aspiration flow path 46. This ensures that high frequency pulses generated by the fluid resonator 276 in the aspiration flow path 46 are not absorbed by the suction source 14, but instead propagate completely up the aspiration flow path 46 to the aspiration catheter 12. In the illustrated embodiment, the fluid actuated valve 274 takes the form of a diaphragm valve, although other types of fluid actuated valves are contemplated.

[0117] The plunger assembly 258 interacts with the plunger cavity 254 to switch the passive pressure oscillation assembly 244 between normal and oscillation modes according to the timing diagram shown in FIG.

[0118] 14, the suction source 14 is first actuated such that the suction catheter 12 is in a free-flow state between any times t0 and t1, and the negative pressure difference between the absolute pressure in the suction flow path 46 and the external ambient pressure experienced by the suction catheter 12 (in this case the negative pressure difference between the pressurized fluid source 16 and the suction flow path 46) is at the negative pressure difference of the free-flow state where the suction catheter 12 draws only blood. During this time, the passive pressure oscillation assembly 244 remains in normal mode. This maximizes the suction efficiency of the system 10 during the free-flow state.

[0119] Between any time t1 and any time t2, thrombus 2 is actively sucked into the distal end 30 of the aspiration catheter 12 such that the negative pressure difference between the absolute pressure in the aspiration flow path 46 and the external ambient pressure experienced by the aspiration catheter 12 falls below the negative pressure difference for a free-flow condition, but not below the negative pressure difference for operation of the passive pressure oscillation assembly 244 designed for zero-flow or low-flow conditions indicative of an obstruction in the aspiration catheter 12 or a flow anomaly in the aspiration conduit of the system 10. Between any time t0 and time t2, the passive pressure oscillation assembly 44 remains in normal mode.

[0120] The state of the passive pressure oscillator assembly 244 shown in Figure 13A during free flow and suction (normal mode) corresponds to "State A" in the timing diagram of Figure 14. As shown in Figure 13A, when there is not sufficient fluid pressure from the inlet channel 262 (through the inlet port 256a of the plunger cavity 254) on the first plunger head 280 of the plunger assembly 258, the spring 260 is configured to apply a biasing force to the plunger assembly 258 that maintains the first plunger head 280 and the second plunger head 282 in a closed position within the plunger cavity 254.

[0121] In its closed position, the first plunger head 280 prevents fluid communication between the front plunger cavity area 284 and the central plunger cavity area 286 via the bypass channel 266, thereby preventing the flow of fluid from the pressurized fluid source 16 through the inlet channel 262, through the bypass channel 266, and into the central plunger cavity area 286. In its closed position, the first plunger head 280 also allows fluid communication between the aspiration passageway 46 and the central plunger cavity area 286 via the pressure equalization channel 272, thereby allowing fluid flow from the aspiration passageway 46 to the central plunger cavity area 286 and equalizing pressures in the aspiration passageway 46 and the central plunger cavity area 286. This allows the passive pressure oscillation assembly 244 to be reset at the beginning of each oscillation cycle.

[0122] In its closed position, the second plunger head 282 blocks fluid communication between the central plunger cavity region 286 and the aspiration passageway 46 via the outlet channel 264, thereby blocking the flow of fluid from the central plunger cavity region 286 through the outlet channel 264 and into the aspiration passageway 46. In its closed position, the second plunger head 282 also blocks fluid communication between the central plunger cavity region 286 and the fluid-actuated valve 274 via the aspiration shutoff channel 270, thereby blocking the flow of fluid from the plunger cavity 254 through the aspiration shutoff channel 270, while allowing fluid communication between the rear plunger cavity region 288 and the fluid-actuated valve 274 via the aspiration shutoff channel 270, thereby allowing the evacuation or backflow of fluid from the fluid-actuated valve 274. This causes the fluid-operated valve 274 located in the aspiration fluid line 46 to be switched to and maintained in its open state, thereby maintaining fluid communication between the suction source 14 and the aspiration fluid line 46 .

[0123] Between any time t1 and any time t2, thrombus 2 is actively sucked into the interior of distal end 30 of aspiration catheter 12 such that the negative pressure difference between the absolute pressure in aspiration channel 46 and the external ambient pressure experienced by aspiration catheter 12 falls below the negative pressure difference for a free-flow condition, but not below the negative pressure difference for actuation of passive pressure oscillation assembly 244 designed for zero or low flow conditions indicative of a clog in aspiration catheter 12 or a flow anomaly in the aspiration conduit of system 10. Between any time t0 and time t2, passive pressure oscillation assembly 44 remains in normal mode because the fluid pressure exerted from inlet channel 262 on first plunger head 280 of plunger assembly 258 is not sufficient to actively oppose the biasing force exerted by spring 260 on plunger assembly 258 to displace first plunger head 280 and second plunger head 282 from their closed positions.

[0124] However, at any time t2, the aspiration catheter 12 becomes clogged with a thrombus 2, so that the negative pressure difference between the absolute pressure in the aspiration channel 46 and the external ambient pressure experienced by the aspiration catheter 12 is rapidly reduced to the actuation negative pressure difference, which is −75 kPa in the illustrated example. Thus, at or shortly after any time t2, the clogging of the aspiration catheter 12 (zero flow or low flow condition) causes the passive pressure oscillation assembly 244 to switch from normal mode to oscillation mode, resulting in both low and high frequency pressure oscillations in the aspiration channel 46, causing pressure pulses to propagate through the aspiration conduit 24 of the aspiration catheter 12, thereby facilitating the removal of the clogged thrombus 2 at the distal end 24 of the aspiration catheter 12 at any time t4.

[0125] Specifically, at any time t 3a , the negative pressure difference between the absolute pressure within the aspiration channel 46 and the external ambient pressure experienced by the aspiration catheter 12 reaches an actuation negative pressure difference.

[0126] As shown in Figures 13B and 13C, during a first stage of operation of the passive pressure vibration assembly 244 in the vibration mode, the presence of sufficient fluid pressure acting on the first plunger head 280 of the plunger assembly 258 from the inlet channel 262 (through the inlet port 256a of the plunger cavity 254) overcomes the biasing force applied to the plunger assembly 258 by the spring 260 and displaces the first plunger head 280 and the second plunger head 282 from a closed position to an open position within the plunger cavity 254.

[0127] In its open position, the first plunger head 280 allows fluid communication between the front plunger cavity region 284 and the central plunger cavity region 286 via the bypass channel 266, thereby allowing fluid flow from the pressurized fluid source 16 through the inlet channel 262, through the bypass channel 266, and into the central plunger cavity region 286. In its open position, the first plunger head 280 also blocks fluid communication between the aspiration passageway 46 and the central plunger cavity region 286 via the pressure equalization channel 272, thereby preventing the continuous flow of fluid from the central plunger cavity region 286 to the aspiration passageway 46 via the pressure equalization channel 272.

[0128] In its open position, the second plunger head 282 allows fluid communication between the central plunger cavity region 286 and the suction passage 46 via the outlet channel 264, thereby allowing fluid flow from the central plunger cavity region 286 through the outlet channel 264 and into the suction passage 46, actuating the fluid resonator 276. In its open position, the second plunger head 282 also allows fluid communication between the central plunger cavity region 286 and the fluid-actuated valve 274 via the suction cut-off channel 270, thereby allowing fluid flow from the plunger cavity 254 through the suction cut-off channel 270. In its open position, the second plunger head 282 also blocks fluid communication between the rear plunger cavity region 288 and the fluid-actuated valve 274 via the suction cut-off channel 270, thereby preventing the drainage or backflow of fluid from the suction cut-off valve 270 into the rear plunger cavity region 288. As such, the fluid-operated valve 274 located in the aspiration fluid line 46 is switched to and maintained in its closed state, thereby preventing fluid communication between the suction source 14 and the aspiration fluid line 46 .

[0129] In this embodiment, the first plunger head 280 and the second plunger head 280 are displaced to their open positions in a two-step process.

[0130] Specifically, as shown in FIG 13B, fluid provided from the pressurized fluid source 16 applies pressure to the first plunger head 280, thereby displacing the first plunger head from its closed position to its open position and allowing fluid communication between the front plunger cavity region 284 and the central plunger cavity region 286 via the bypass channel 266. As a result, fluid flows from the pressurized fluid source 16 through the inlet channel 262 into the front plunger cavity region 284 and through the bypass channel 266 into the central plunger cavity region 286. The state of the passive pressure oscillation assembly 244 shown in FIG 13B corresponds to "State B" in the timing diagram of FIG 14. The flow of fluid into the central plunger cavity region 286 exerts an additional force on the second plunger head 280 and thus the spring 260, thereby further displacing the second plunger head 280 from its closed position to its fully open position (FIG. 13C), allowing fluid communication between the central plunger cavity region 286 and the aspiration passageway 46 via the outlet channel 264, and between the central plunger cavity region 286 and the fluid-actuated valve 274 via the aspiration shutoff channel 270. As a result, fluid flows from the central plunger cavity region 286 through the outlet channel 264 to the aspiration passageway 46, and from the central plunger cavity region 286 through the aspiration shutoff channel 270, thereby causing the fluid-actuated valve 274 to its closed state. The state of the passive pressure oscillation assembly 244 shown in FIG. 13C corresponds to "State C" of the timing diagram of FIG. 14. Note that the pressure between the front plunger cavity region 284 and the central plunger cavity region 286 will be the same in state B (i.e., equal between states A and B), but because the surface area of ​​the second plunger head 280 is greater than the surface area of ​​the first plunger head 280, the force exerted on the second plunger head 280 by the fluid in the central plunger cavity region 286 will be greater than the force exerted on the first plunger head 280 by the fluid in the front plunger cavity region 284.As a result, an additional net force is applied to the plunger assembly 258, and thus the spring 260, thereby "kick" the second plunger head 280 from its closed position to its open position.

[0131] As can be seen from FIG. 14, at any time t 3a and any time t 3b Between t and t, the inflow of fluid into the aspiration channel 46 gradually increases the negative pressure difference between the absolute pressure in the aspiration channel 46 and the external ambient pressure experienced by the aspiration catheter 12 to a stop negative pressure difference, which in the illustrated case is -10 kPa, thereby completing the first stage of operation of the passive pressure oscillation assembly 244 in the oscillation mode. 3a and any time t 3b Between the aspiration catheter 12 and the aspiration passage 46, the negative pressure difference between the absolute pressure and the external ambient pressure experienced by the aspiration catheter 12 is also pulsed at low amplitude but high frequency through the operation of the fluid resonator 276.

[0132] 13D and 13E, during a second stage of operation of the passive pressure vibration assembly 244 in the vibration mode, when there is sufficient fluid pressure from the pressure tap channel 268 (through the pressure tap port 256e of the plunger cavity 254) on the second plunger head 282 of the plunger assembly 258, the biasing force applied by the spring 260 to the plunger assembly 258 is compensated to return the first plunger head 280 and the second plunger head 282 from the open position to the closed position within the plunger cavity 254. In particular, the pressure tap channel 268 is the primary differential pressure tap (or sensing line) and is critical to the function of the passive pressure vibration assembly 244. For any negative pressure difference between the absolute pressure within the aspiration passageway 46 and the external ambient pressure experienced by the aspiration catheter 12, when the second plunger head 282 is in its open state, the net force on the plunger assembly 258, and therefore the spring 260, is between the central plunger cavity area 286 and the rear plunger cavity area 288 due to the larger surface area of ​​the second plunger head 282 relative to the surface area of ​​the first plunger head 280. When the second plunger head 282 is in its closed state, the net force on the plunger assembly 258 is between the front plunger cavity area 284 and the rear plunger cavity area 288 and is smaller due to the smaller surface area of ​​the first plunger head 280 relative to the surface area of ​​the second plunger head 280.

[0133] Also, in its closed position, the second plunger head 282 blocks fluid communication between the central plunger cavity region 286 and the fluid-operated valve 274 via the suction shutoff channel 270, thereby stopping the flow of fluid from the plunger cavity 254 through the suction shutoff channel 270 (FIG. 13D). The fluid-operated valve 274 located in the suction channel 46 is then returned to its closed state, thereby re-establishing fluid communication between the suction source 14 and the suction channel 46. The state of the passive pressure oscillation assembly 244 shown in FIG. 13D corresponds to "State D" in the timing diagram of FIG. 14. Also, in its closed position, the second plunger head 282 blocks fluid communication between the central plunger cavity region 286 and the suction channel 46 via the outlet channel 264, thereby stopping the flow of fluid from the central plunger cavity region 286 through the outlet channel 264 into the suction channel 46 (FIG. 13E). Additionally, in its closed position, the second plunger head 282 allows fluid communication between the rear plunger cavity region 288 and the suction shutoff channel 270, thereby allowing the drainage or backflow of fluid from the fluid-operated valve 274 into the rear plunger cavity region 288. As a result, the fluid-operated valve 274 is returned to its closed state, re-establishing fluid communication between the suction source 14 and the suction flow passage 46.

[0134] In its closed position, the first plunger head 280 blocks fluid communication between the front plunger cavity region 284 and the central plunger cavity region 286 via the bypass channel 266, thereby stopping the flow of fluid from the pressurized fluid source 16 through the inlet channel 262, through the bypass channel 266, and into the central plunger cavity region 286 (FIG. 13E). In its closed position, the first plunger head 280 also allows fluid communication between the aspiration passageway 46 and the central plunger cavity region 286 via the pressure equalization channel 272, thereby allowing fluid flow from the central plunger cavity region 286 to the aspiration passageway 46, equalizing pressure between the aspiration passageway 46 and the central plunger cavity region 286 (FIG. 13E). The state of the passive pressure oscillation assembly 244 shown in FIG. 13E corresponds to "State E" in the timing diagram of FIG. 14.

[0135] In particular, the negative pressure difference between the absolute pressure in the aspiration channel 46 and the external ambient pressure experienced by the aspiration catheter 12 increases over a given time t 3b To ensure that the first and second plunger heads 280, 282 remain in the open position until a stopping negative pressure differential is reached at , the larger diameter of the second plunger head 282 relative to the diameter of the first plunger head 280 increases the pressure applied to the second plunger head 282 by the fluid in the pressure tap channel 268 required to displace the plunger assembly 258 to return the first and second plunger heads 280, 280 to the closed position.

[0136] At any time t 3b and any time t 3c Between time t, the negative pressure difference between the absolute pressure within the aspiration channel 46 and the external ambient pressure experienced by the aspiration catheter 12 decreases rapidly. 3c If the thrombus 2 in the suction catheter 12 is not removed at any time t 3dAt time t 3c If the thrombus 2 in the suction catheter 12 is removed, the removal from the suction catheter 12 (free flow condition) will cause the passive pressure oscillation assembly 244 to switch from the oscillation mode to the normal mode, thereby stopping the pressure oscillation in the suction flow path 46 and causing pressure pulses to stop propagating to the suction conduit 24 of the suction catheter 12, as shown at any time t4.

[0137] While particular embodiments have been disclosed and described herein, they are not intended to limit the disclosed invention, and it will be apparent to one skilled in the art that various changes, substitutions and modifications (e.g., various part dimensions, combinations of parts) can be made without departing from the scope of the disclosed invention, which is defined solely by the following claims and equivalents thereof. Accordingly, the specification and drawings are to be regarded in an illustrative sense, and not in a restrictive sense. The various embodiments disclosed and described herein are intended to cover alternatives, modifications and equivalents of the disclosed invention, which may fall within the scope of the appended claims.

Claims

1. A manifold, comprising: a suction outlet configured to be fluidly coupled to a suction source; a suction inlet configured to be fluidly coupled to the suction catheter such that a suction flow path is formed between the suction catheter and the suction source, the suction flow path having an absolute pressure during free flow that creates a negative pressure difference in a free flow state between the suction outlet and the suction inlet; a relief inlet configured to be fluidly coupled to a pressurized fluid source; a pressure oscillation assembly fluidly coupled between the relief inlet and the suction flow path, the pressure oscillation assembly operating between a normal mode that blocks fluid communication between the pressurized fluid source and the suction flow path and an oscillation mode that pulsates the fluid communication between the pressurized fluid source and the suction flow path, such that the negative pressure difference between the suction outlet and the suction inlet oscillates between a first negative pressure difference smaller than the pressure difference in the free flow state and a second negative pressure difference larger than the pressure difference in the free flow state.

2. The manifold according to claim 1, wherein the first negative pressure difference is an operating pressure difference for operating the pressure oscillation assembly to gradually increase the negative pressure difference between the suction outlet and the suction inlet, and the second negative pressure difference is a stopping pressure difference for operating the pressure oscillation assembly to gradually decrease the negative pressure difference between the suction outlet and the suction inlet.

3. The manifold according to claim 1, wherein pulsating the fluid communication between the pressurized fluid source and the suction flow path propagates pressure pulses within the suction flow path.

4. The manifold according to claim 1, wherein pulsating the fluid communication between the pressurized fluid source and the suction flow path propagates a reverse flow of fluid within the suction flow path.

5. The manifold according to claim 1, wherein the pressurized fluid source includes ambient air.

6. The manifold according to claim 1, wherein the pressurized fluid source includes a reservoir containing a liquid.

7. The manifold according to claim 1, wherein the second pressure difference is 40 kPa to 90 kPa greater than the first pressure difference.

8. In the manifold according to claim 1, the manifold characterized in that the second pressure difference is at least 60 kPa greater than the first pressure difference.

9. In the manifold according to claim 1, the pressure oscillation assembly is configured to pulse the fluid communication between the pressurized fluid source and the suction flow path simultaneously at a first frequency and a second frequency different from the first frequency.

10. In the manifold according to claim 9, the manifold characterized in that the second frequency is greater than the first frequency.

11. In the manifold according to claim 10, the manifold characterized in that the first frequency is in the range of 0.2 Hz to 10 Hz and the second frequency is in the range of 100 Hz to 400 Hz.

12. In the manifold according to claim 1, the pressure oscillation assembly is a passive pressure oscillation assembly configured to be actuated to automatically switch from the normal mode to the oscillation mode in response to a clogged thrombus in the suction catheter.

13. In the manifold according to claim 12, the manifold characterized in that the passive pressure oscillation assembly is configured to be actuated to automatically switch from the oscillation mode to the normal mode in response to the removal of the clogged thrombus from the suction catheter.

14. In the manifold according to claim 12, the passive pressure oscillation assembly includes a plunger cavity that fluidly communicates between the relief inlet and the suction flow path, and a plunger assembly slidably disposed within the plunger cavity, the passive pressure oscillation assembly blocking the fluid communication between the pressurized fluid source and the suction flow path through the plunger cavity when in the normal mode and pulsing the fluid communication between the pressurized fluid source and the suction flow path at a first frequency when in the oscillation mode.

15. In the manifold according to claim 14, The plunger assembly includes a rod, a first plunger head fixed to the rod, and a second plunger head fixed to the rod at a distance from the first plunger head, thereby forming in the plunger cavity a front plunger cavity region, a central plunger cavity region between the first plunger head and the second plunger head, and a rear plunger cavity region. The passive pressure oscillation assembly further includes an inlet channel that provides fluid communication between the relief inlet and the front plunger cavity region, an outlet channel that conditionally provides fluid communication between the central plunger cavity region and the suction channel, a bypass channel that conditionally provides fluid communication between the front plunger cavity region and the central plunger cavity region, When the passive pressure oscillation assembly is in the normal mode, the plunger assembly is configured to maintain the first plunger head in a closed position within the plunger cavity to prevent fluid communication between the front plunger cavity region and the central plunger cavity region through the bypass channel, and to maintain the second plunger head in a closed position within the plunger cavity to prevent fluid communication between the central plunger cavity region and the suction channel through the outlet channel, thereby preventing fluid communication between the pressurized fluid source and the suction channel through the plunger cavity. When the passive pressure oscillation assembly is in the oscillation mode, the plunger assembly displaces the first plunger head from a closed position in the plunger cavity to an open position, enabling fluid communication between the front plunger cavity region and the central plunger cavity region via the bypass channel. Further, the second plunger head is displaced from a closed position in the plunger cavity to an open position, enabling fluid communication between the central plunger cavity region and the suction flow path. Then, by returning the first plunger head and the second plunger head from the open position to the closed position, the fluid communication between the pressurized fluid source and the suction flow path is configured to be pulsed at a first frequency. A manifold characterized by this.

16. In the manifold according to claim 15, The passive pressure oscillation assembly further includes a spring configured to apply a biasing force to the plunger assembly to maintain the first plunger head and the second plunger head in a closed position within the plunger cavity during operation of the passive pressure oscillation assembly in the normal mode. The plunger assembly, in response to the pressure applied by the fluid supplied to the plunger assembly from the pressurized fluid source through the inlet channel during operation of the passive pressure oscillation assembly in the oscillation mode, overcomes the biasing force applied to the plunger assembly by the spring, displacing the first plunger head and the second plunger head from a closed position in the plunger cavity to an open position. Then, it is configured to supplement the biasing force applied to the plunger assembly by the spring and return the first plunger head and the second plunger head from the open position to the closed position. A manifold characterized by this.

17. In the manifold according to claim 16, The passive pressure oscillation assembly further includes a pressure tap channel that provides fluid communication between the suction flow path and the rear plunger cavity region. The plunger assembly is configured to, in response to the pressure applied by the fluid supplied from the suction flow path to the plunger assembly through the pressure tap channel during the operation of the passive pressure vibration assembly in the vibration mode, supplement the biasing force applied to the plunger assembly by the spring, and return the first plunger head and the second plunger head from the open position to the closed position. A manifold characterized by that.

18. In the manifold according to claim 15, The plunger cavity has a first portion having a certain diameter and a second portion having a diameter larger than that of the first portion. The first plunger head has a certain diameter, and the second plunger head has a diameter larger than that of the first plunger head, and the first plunger head is configured to be displaced within the first portion, and the second plunger head is configured to be displaced within the second portion. A manifold characterized by that.

19. In the manifold according to claim 15, A fluid-operated valve disposed in the suction flow path; Further comprising a suction cutoff channel that is conditionally in fluid communication between the central plunger cavity region and the fluid-operated valve, The second plunger head, when in the closed position, blocks the fluid communication between the central plunger cavity region and the fluid-operated valve via the suction cutoff channel, and allows the fluid communication between the rear plunger cavity region and the fluid-operated valve via the suction cutoff channel. When in the open position, it is configured to allow the fluid communication between the central plunger cavity region and the fluid-operated valve via the suction cutoff channel, and block the fluid communication between the rear plunger cavity region and the fluid-operated valve via the suction cutoff channel. A manifold characterized by that.

20. ​ ​ ​ ​ The manifold further includes a pressure equalization channel that is conditionally in fluid communication between the suction channel and the central plunger cavity region, and the first plunger head is configured to allow fluid communication between the suction channel and the central plunger cavity region when in the closed position and to block fluid communication between the suction channel and the central plunger cavity region when in the open position.

22. The manifold according to claim 15, further comprising a resonance device disposed within the outlet channel, the resonance device being configured to pulse fluid communication between the plunger cavity and the suction channel at a second frequency different from the first frequency when the passive pressure vibration assembly is in the vibration mode.

23. The manifold according to claim 22, wherein the second frequency is greater than the first frequency.

24. The manifold according to claim 22, wherein the resonance device is a paddle wheel.

25. A suction system comprising the manifold according to claim 1, a suction source coupled to the suction outlet, a suction catheter coupled to the suction inlet, and a pressurized fluid source coupled to the relief inlet.

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