A pulse-relief balloon dilation pump and method for intracranial arterial stenosis

Abstract

This invention discloses a pulse-release balloon dilation pump and method for intracranial arterial stenosis. Addressing the mechanical mechanism of thin intracranial arterial walls and irregular plaques leading to axial stress accumulation and subsequent complications such as dissection and detachment, this invention adds a pulse-release control unit to a conventional pressure pump. Its core physical principle is as follows: When the balloon dilates at an irregular plaque, the intramural strain energy density distribution is uneven. Static friction constraint keeps the system in a high-energy metastable state, and the accumulated elastic potential energy ΔU continuously increases with expansion. The constraint factor λ is defined as F_required / f_max; when λ>1, the balance is unstable, and energy suddenly bursts. This invention uses periodic short-term pressure release to instantaneously decrease the contact pressure, reduce the static friction limit, and briefly raise λ to >1, actively triggering micro-slippage, releasing a small portion of the accumulated energy each time, achieving segmented and gentle energy release. Pulse parameters (amplitude, frequency, etc.) can be flexibly adjusted according to actual clinical conditions. The pulse mode offers flexible and diverse usage options. Operators can initiate it synchronously in the early stages of dilation, when risk signs appear, intervene as needed during pressure application, or combine multiple methods, allowing the operator to independently determine the operational procedure. Based on thin-film mechanics, tribology, and viscoelasticity theories, this invention is simple to operate, does not alter the clinical procedure, and effectively reduces the risk of complications during intracranial artery stenosis balloon angioplasty.

Description

Technical Field

[0001] This invention belongs to the field of neurointerventional medical device technology, specifically relating to a balloon dilation pressure pump and method for reducing axial stress accumulation through pulse pressure relief in intracranial arterial stenosis. Background Technology

[0002] Intracranial arterial atherosclerotic stenosis is a major cause of ischemic stroke, and balloon angioplasty is a commonly used interventional treatment. However, intracranial arteries have unique anatomical and pathological characteristics: their walls are thin and fragile, lacking the support of a complete external elastic lamina; and the stenotic plaques are often eccentric, irregular in shape, and heterogeneous in texture. These characteristics make the risk of complications from intracranial artery balloon angioplasty significantly higher than that of arteries in other locations.

[0003] The mechanical forces involved in balloon dilation can be decomposed into two orthogonal components: radial stress perpendicular to the vessel wall and axial stress parallel to the long axis of the vessel. Radial stress acts on the vessel wall and plaque, causing plaque remodeling and deformation through compression, thus achieving lumen reconstruction; this is the beneficial mechanical component required for treatment. On the other hand, axial stress acts on the balloon-plaque interface and is the main mechanical cause of complications such as vascular dissection, plaque detachment, perforator occlusion, and balloon slippage.

[0004] 1. The root cause of uneven strain energy density distribution Intracranial arterial stenosis plaques are often eccentric and irregular in shape. When the balloon dilates in the lesion segment, the balloon wall comes into contact with the irregular plaque surface, forming a complex geometric constraint boundary. According to the principle of minimum potential energy in elasticity, the balloon membrane will take the deformation shape that minimizes the total potential energy under given boundary conditions. Due to the change in the curvature of the plaque surface, the balloon membrane undergoes different degrees of tensile deformation in different regions—the radius of curvature of the balloon membrane corresponding to the plaque protrusion is larger, and according to the Laplace relation T = P·R (cylindrical approximation), the intramural tension in this region is higher; conversely, the tension is lower in the flatter regions.

[0005] From an energy perspective, the elastic potential energy stored within the membrane can be described by the strain energy density w = (1 / 2)σ:ε (the double dot product of the stress tensor and the strain tensor). Due to the non-uniform distribution of the stress field, the strain energy density exhibits a spatial gradient within the membrane—high strain energy density in areas of intense tension and low strain energy density in areas of gentle tension. This non-uniform distribution of strain energy density is the energy source of axial stress.

[0006] 2. Static friction constraint and energy accumulation When the balloon and the plaque are relatively stationary, the static friction force generated at the contact interface constrains the tangential displacement of the membrane surface, preventing the balloon membrane from freely approaching the natural equilibrium state with minimum strain energy density. From the variational principle perspective, static friction introduces an additional constraint, "freezing" the system into a high-energy state higher than the frictionless equilibrium state.

[0007] The "frozen" extra potential energy ΔU = U_constrained - U_unconstrained is precisely the accumulated elastic potential energy. The magnitude of ΔU is positively correlated with the degree of uneven distribution of intramural strain energy density. This ΔU macroscopically manifests as the axial force acting on the balloon-plaque interface—which can be defined as the integral effect of the projection of the intramural strain energy density gradient onto the vascular axis.

[0008] As the pressure inside the balloon continues to rise, the contact pressure between the balloon and the plaque increases, causing plaque deformation. This may further exacerbate the uneven stretching of the balloon membrane, leading to a continuous increase in the uneven distribution of strain energy density. To maintain equilibrium, the required static friction force also increases accordingly, placing the system in a metastable state where energy is continuously injected but cannot be released due to frictional constraints.

[0009] 3. Critical conditions for stress burst Define the constraint factor λ = required tangential constraint force (F_required) / maximum static friction force (f_max), where F_required is the tangential constraint force required to maintain the current deformation state (i.e., the axial force obtained by integrating the strain energy density gradient), and f_max = μ_s·N is the maximum static friction force (μ_s is the static friction coefficient, and N is the normal contact pressure).

[0010] When λ < 1, the system is in a stable equilibrium state; when λ > 1, static equilibrium is unstable. Since the dynamic friction coefficient μ_k is much smaller than the static friction coefficient μ_s, once instability occurs, the system enters a positive feedback acceleration state—the resistance decreases after the motion begins, leading to accelerated motion and more violent energy release. The accumulated elastic potential energy ΔU is suddenly released in the form of a shock wave in a very short time, causing violent damage to vascular tissue, directly leading to serious complications such as intimal tearing (dissection), plaque fragmentation and detachment (distal embolism), compression and occlusion of perforator openings, and sudden displacement of the balloon (slippage).

[0011] The above analysis shows that static friction is both necessary to maintain the current equilibrium and a condition for the accumulation of axial stress. Reducing stress accumulation and preventing it from reaching the critical point of failure is key to reducing the risk of complications.

[0012] Traditional manual pressure dilation methods can only provide continuous pressure and cannot actively intervene in this stress accumulation process. Although surgeons have experience-based judgment, they lack effective tools to reduce stress concentration and lower the risk of complications. Summary of the Invention

[0013] (a) Inventive Principle The core of this invention lies in: by rapidly expanding the volume of the pressure pump cavity in a short period of time, the system pressure drops instantaneously, and the balloon elastically retracts, thereby actively intervening in the static equilibrium state of the balloon-plaque interface, allowing the accumulated axial stress to be released in segments and gently, and avoiding sudden stress bursts.

[0014] 1. Mechanical intervention mechanism of pulse pressure relief The pulse decompression system of this invention consists of a pressure pump, connecting tubing, and a balloon forming a closed hydraulic circuit, the interior of which is filled with a mixed medium (such as a mixture of contrast agent and physiological saline). According to Pascal's principle, the pressure is equal everywhere in the system. The pressure pump applies pressure to the medium through a piston, and this pressure is transmitted to the balloon through the tubing, causing the balloon to inflate.

[0015] When the pulse pressure relief control unit instructs the pressurization mechanism to rapidly expand the volume of the pressure pump chamber (such as a servo motor driving the piston to retreat rapidly, or a piezoelectric actuator to contract rapidly), the pressure drop causes the pressure P inside the balloon to decrease, and the balloon retracts under its own elasticity.

[0016] The balloon retraction causes an instantaneous decrease in the contact pressure N at the balloon-plaque interface, proportional to the relationship N = k·P, where k is a coefficient related to the contact geometry. According to Coulomb's law of friction, the static friction limit f_max = μ_s·N = μ_s·k·P. When the pressure inside the balloon decreases from P0 to P1, the static friction limit decreases from f_max0 to f_max1 = (P1 / P0)·f_max0.

[0017] The initial equilibrium state satisfies: f_max0 = F_required (the actual static friction force equals the required constraint force). When the pressure relief makes f_max1 < F_required, the constraint factor λ = F_required / f_max1 > 1, the static equilibrium is broken, and a small relative motion occurs between the balloon and the plaque.

[0018] At this instant, the strain energy within the membrane, previously locked by friction, is locally released. The system locally relaxes from a high-energy state to a low-energy state, releasing a portion of the accumulated elastic potential energy δU. The magnitude of δU is related to the pressure relief amplitude. By appropriately selecting the pressure relief amplitude, δU can be made much smaller than the total accumulated energy, ensuring a gentle and controllable release process.

[0019] During release, the area of ​​intense stretching of the balloon membrane slightly slips towards the area of ​​gentle stretching, the strain energy density distribution within the membrane tends to become uniform, and the constraint factor λ falls back to a safe range.

[0020] 2. Self-limiting and controllable properties of slip It is important to note that the minute slip triggered by each pressure release is self-limiting and will not develop into uncontrolled continuous slip. This is because: (1) Attenuation of driving force: During the slip process, the intramembrane tension difference ΔT gradually decreases as the elastic potential energy is released. According to the law of conservation of energy, the released elastic potential energy δU is equal to the work done by the frictional force during the slip process, δU = ∫ f·ds. As ΔT decreases, the driving force of slip gradually weakens; (2) Rapid recovery of constraint: The pressure relief pulse lasts for a very short time (milliseconds), and then the pressure quickly recovers to the target level. After the pressure recovers, the contact pressure N rises, and the static friction limit f_max = μ_s·N increases back to the initial level.

[0021] When the condition ΔT < f_max is met, the slippage naturally stops, and the system re-enters the static friction lock state. The entire process is similar to "micro-motion" rather than "sliding"—each slippage distance is typically on the micrometer scale, and the released energy δU is much smaller than the total accumulated energy ΔU.

[0022] By repeatedly executing the "depressurization-slippage-lock-re-depressurization" cycle, the accumulated energy is released in stages and in a controlled manner. This mechanism is highly similar to the ABS anti-lock braking system—it does not completely release the brakes, but keeps the system in a controllable state through repeated "brake-release" cycles, thus preventing uncontrolled slippage.

[0023] 3. Principles for selecting pulse parameters The core of pulsed pressure relief lies in keeping the system away from the critical burst point through periodic perturbations, rather than relying on a fixed set of parameters. Specific parameters should be selected based on the actual clinical situation. Decompression amplitude: It must meet the condition of reliably triggering the breaking of static equilibrium (i.e., ensuring that the probability of f_max1 < F_required after decompression is sufficiently high). Too small an amplitude may not effectively trigger stress release, while too large an amplitude may excessively reduce the expansion effect. In clinical application, the operator can adjust it within an appropriate range according to factors such as plaque hardness and vascular conditions.

[0024] Pulse frequency: The viscoelastic response characteristics of biological tissues must be considered. After each pressure release, the tissue needs a certain amount of time to complete stress release and recovery. Too high a frequency may lead to incomplete response, while too low a frequency may cause excessive stress accumulation during the interval. Generally, a frequency range that matches the tissue stress relaxation time can be selected.

[0025] Operators can flexibly select appropriate pulse parameters in clinical practice based on factors such as the specific characteristics of the lesion, the type of balloon, and the purpose of dilation, in order to achieve the best therapeutic effect.

[0026] 4. The essential differences from existing technologies From a system dynamics perspective, traditional manual pressurization expansion passively waits for energy to accumulate to a critical point before naturally exploding (releasing all ΔU in a single burst). This invention, however, actively intervenes in the early stages of energy accumulation, releasing it in stages before reaching a dangerous level (releasing δU multiple times, ΣδU = ΔU). This "active depressurization and staged release" strategy fundamentally changes the energy dissipation path of the system.

[0027] Dimension Traditional manual pressure expansion This invention Energy Path Passive accumulation → Single burst Active intervention → phased release control variables Control only the pressure level Control pressure time structure System status Static balance (locked) Dynamic equilibrium (intermittent slippage) Energy dissipation Sudden and uncontrollable Mild and controllable Physical essence Static friction locking system Vibration and friction reduction system

[0028] (ii) Purpose of the invention The purpose of this invention is to provide a balloon dilation pressure pump and method that reduces axial stress accumulation by pulsating pressure relief, specifically targeting the characteristics of intracranial arterial stenosis, thereby reducing the risk of intraoperative complications.

[0029] (III) Technical Solution

[0030] 1. Pulse-relief balloon dilation pressure pump A pulse-relief balloon dilation pressure pump for intracranial arterial stenosis, characterized in that it comprises: Pump body: Used to contain pressurized media; Pressure output interface: used to connect the balloon catheter; Pressurization mechanism: used to apply pressure to the pump body; Pressure display unit: Used to display the current pressure value in real time; Pulse pressure relief control unit: used to control the pressurization mechanism to perform periodic short-term pressure relief; The pulse pressure relief control unit includes: - Pulse mode start module: Used to start or stop pulse pressure relief mode; - Execution module: In pulse mode, it controls the pressurization mechanism to periodically execute the "short-time pressure relief-pressure recovery" cycle.

[0031] Adjustability of pulse parameters: The amplitude, frequency, and other parameters of the pulse pressure relief can be adjusted according to clinical needs. For reference, the following parameter ranges can be used for initial setting in clinical practice, and further optimized based on actual clinical conditions: - Pressure relief range: 10%~30% of current pressure. - Pulse frequency: 0.5~2Hz

[0032] The pulse decompression mode can be activated at different stages of the dilation process. The specific method is determined by the surgeon based on intraoperative observation and clinical experience, and mainly includes the following typical scenarios: Scenario 1: Synchronous initiation of early expansion: The surgeon routinely pressurizes the balloon until it just begins to deploy and make contact with the plaque. From this point onward, the pulse depressurization mode is simultaneously activated so that the entire expansion process (from low pressure to target pressure) is carried out under pulse perturbation. Scenario 2: Activation upon the appearance of risk signs: The operator first applies pressure to the target pressure as usual and maintains constant pressure for expansion; when risk signs that may indicate stress accumulation are observed (such as asymmetry of curvature on both sides of the lowest point of the balloon shown on angiography, abnormal expansion resistance, etc.), the pulse decompression mode is activated to perform periodic decompression while maintaining the target pressure; Scenario 3: Timely intervention during pressurization: As the operator gradually increases the pressure from the initial pressure to the target pressure, the pulse depressurization mode can be activated at any time based on real-time observation; the pulse can be performed synchronously with the pressurization process, or the pressurization can be paused after a certain intermediate pressure is reached, and the pulse cycle can be executed separately; Scenario 4: Combination of multiple methods: The above scenarios can be flexibly combined according to clinical needs, such as continuing pulse after the target pressure is reached by early synchronous pulse, or first routinely pressurizing to the intermediate pressure, pulse depressurization, then continue pressurizing to the target pressure, and pulse again, etc.

[0033] During the pulsed process, a slight relative motion occurs between the balloon and the plaque interface at each moment of decompression, causing a redistribution of the intramural strain energy density and releasing the accumulated axial stress. The operator can adjust the pulse parameters or stop the pulse at any time to return to the conventional constant pressure mode. The core of this invention lies in providing pulsed decompression as an active intervention method, with the specific operating procedure determined by the operator based on the clinical situation.

[0034] How the pressurization mechanism is implemented: - Method 1: Servo motor driven, pressure control is achieved through a precision lead screw-piston mechanism, response time <20ms; - Method 2: Piezoelectric drive, using encapsulated piezoelectric ceramic actuators, with a response time of <0.1ms and higher precision;

[0035] 2. Pulse-relief balloon dilation method A method for balloon dilation of intracranial arterial stenosis using the aforementioned pressure pump, characterized by comprising the following steps: Step 1: Conventional Expansion Connect the pressure pump to the balloon catheter and apply pressure as usual to inflate the balloon until it contacts the plaque; Step 2: Pulse pressure relief initiation and execution When the surgeon independently determines that it is necessary to reduce the accumulation of axial stress based on intraoperative observations (such as the degree of irregularity of plaque morphology, the feeling of resistance to expansion, etc.), the pulse pressure relief mode is activated. The timing of pulse mode activation is flexible and varied. It can be activated simultaneously with pressure in the early stage of dilation, activated after the target pressure is reached, intervened at appropriate times during pressure, or used in combination according to clinical needs. After startup, the pressure pump maintains the current pressure and automatically executes a periodic "short-term pressure relief-pressure recovery" cycle according to preset parameters; Each time pressure is released, the constraint factor λ briefly rises to >1, the static balance is broken, the balloon and plaque undergo slight relative motion, the intramural strain energy density is redistributed, and the accumulated elastic potential energy is gently released; the operator can adjust parameters such as pulse amplitude and frequency according to real-time clinical response, and can also stop the pulse at any time to return to the conventional constant pressure mode; Step 3: Expansion Completed Once the predetermined expansion time or effect is achieved, stop the pulse, depressurize, and remove the balloon.

[0036] (iv) Beneficial effects 1. Designed for the specific pathological anatomy of intracranial arteries: Based on the clinical characteristics of thin intracranial vessel walls and irregular plaques, the design addresses the root cause of complication, axial stress accumulation, through pulse pressure relief. 2. Clear mechanism and reliable principle: Based on classical theories such as thin film mechanics (strain energy density distribution), tribology (constraint factor λ), and hydraulic principle (pressure-volume response), it actively breaks the static equilibrium and releases accumulated energy in stages through periodic short-term pressure relief, thus blocking the stress burst path from the mechanical root. 3. Parameters are flexible and adjustable to adapt to clinical diversity: parameters such as pulse amplitude and frequency can be adjusted according to different lesion characteristics, balloon type and dilation purpose, allowing operators to flexibly select the best parameter combination in clinical practice; 4. Simple operation, does not change the routine clinical procedure: The operator performs pressure dilation in the conventional way, and can start the pulse decompression mode with one button when needed, without the need for additional complicated operations; 5. Independent of the monitoring system, autonomous judgment: The surgeon determines the timing of activation based on clinical experience, without relying on complex monitoring equipment, thus reducing system complexity and cost; 6. Simple structure and easy to promote: It can be achieved by adding a pulse pressure relief control unit to a conventional pressure pump, which makes the cost controllable and suitable for widespread clinical use; 7. Self-limiting slippage, safe and controllable: The minute slippage triggered by each pressure release is self-limiting. The driving force decays as energy is released, and the friction force re-establishes the constraint after the pressure is restored, ensuring that the slippage will not get out of control and is gentle and controllable throughout the process. Attached Figure Description

[0037] Figure 1This is a schematic diagram of the pressure pump structure of the present invention; Figure 2 This is a flowchart of the method of the present invention.

[0038] Explanation of reference numerals in the attached figures: 1-Pump housing, 2-Pressurized medium chamber, 3-Pressure display unit, 4-Rotating column, 5-First piston, 6-Second piston, 7-Pulse pressure relief control unit switch, 8-Servo motor or piezoelectric actuator, 9-Pressure output conduit. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments.

[0040] Example 1: Intracranial Arterial Stenosis and Dilation The patient had approximately 80% stenosis of the middle cerebral artery, with an irregular, eccentric plaque morphology. The pressure pump of this invention was used for dilation.

[0041] The operator applied pressure to 2 atm using the standard method, and once the balloon made contact with the plaque, the operator decided to activate the pulse decompression mode.

[0042] The initial pressure relief was set to 0.4 atm (approximately 20%) and 1 Hz, and the pressure pump began periodic pressure relief. Simultaneously, manual pressurization continued until the target pressure (e.g., 5 atm) was reached, with continuous pulse pressure relief. After the pulse pressure relief mode ended, constant pressure was maintained for 30 seconds before depressurization and balloon withdrawal. Postoperative angiography showed satisfactory lumen coverage.

[0043] Example 2: Parameter adjustment for different lesions The patient's plaque was hard, and the initial pulse parameters did not show significant effect. The operator appropriately increased the pressure relief amplitude to 0.9 atm and decreased the frequency to 0.5 Hz to enhance the effect of a single pulse. Satisfactory results were achieved after 20 seconds of pulse.

Claims

1. A pulse-relief balloon dilation pressure pump for intracranial arterial stenosis, characterized in that, include: Pump body, used to contain pressurized medium; Pressure output interface for connecting balloon catheter; The pressurization mechanism is used to apply pressure to the pump body; The pressure display unit is used to display the current pressure value in real time. The pulse pressure relief control unit is used to control the pressurization mechanism to perform periodic short-term pressure relief. The pulse pressure relief control unit includes: a pulse mode start module, used to start or stop the pulse pressure relief mode; In pulse mode, the execution module controls the pressurization mechanism to periodically execute the "short-time pressure relief-pressure recovery" cycle.

2. The pressure pump according to claim 1, characterized in that, The pulse pressure relief control unit also includes a parameter adjustment module for adjusting the amplitude and / or frequency of the pulse.

3. The pressure pump according to claim 1, characterized in that, The pulse decompression mode can be manually started or stopped by the surgeon during routine dilation.

4. The pressure pump according to claim 1, characterized in that, The pressurization mechanism is a piston mechanism driven by a servo motor or a piezoelectric actuator.

5. A method for balloon dilation of intracranial arterial stenosis using the pressure pump according to any one of claims 1-4, characterized in that, Includes the following steps: Connect the pressure pump to the balloon catheter and pressurize to the target dilation pressure as usual; Based on clinical judgment, activate the pulse pressure relief mode; The pressure pump performs a periodic "short-term pressure relief-pressure recovery" cycle; Once the desired expansion effect is achieved, stop the pulse, depressurize, and remove the balloon.

6. The method according to claim 5, characterized in that, During the execution of the pulse pressure relief mode, the amplitude and / or frequency of the pulse can be adjusted according to the clinical response.

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