Vessel dilation estimation for intravascular balloon catheter

Abstract

An apparatus includes an endoflator configured for fluid communication with an intravascular catheter and to inflate a balloon of the intravascular catheter with a fluid. At least one of the intravascular catheter or the endoflator includes a sensor configured to provide an output. The apparatus also includes a processor configured to compute a compliance of the balloon based on the output of the sensor, and to provide, to a display, a visual representation of the compliance of the balloon.

Description

VESSEL DILATION ESTIMATION FORINTRAVASCULAR BALLOON CATHETERTECHNICAL FIELD

[0001] The subject matter described herein relates to systems, devices, and methods for estimating vessel dilation for intravascular balloon catheters. The vessel compliance estimation system disclosed herein has particular but not exclusive utility for detecting fracturing of calcified vascular stenoses inside of a blood vessel.BACKGROUND

[0002] Many individuals (especially elderly individuals) suffer from progressively enlarging vascular calcium mineral deposits. Such vascular calcification can cause symptoms such as compromised vascular integrity, vascular stenoses, hypertension, enlargement of the heart, ischemia, and congestive heart failure. The severity and extent of mineralization are strong predictors for morbidity and mortality. Vascular calcification may be recognized as a pathobiological process similar in some ways to bone formation. Vascular (e.g., arterial and venous) calcifications can be a persistent problem when treating coronary or peripheral vessels.

[0003] Many types of stenosis can be treated at least partially with balloon angioplasty to dilate the vessel at the location of the stenosis. In some cases, a stent may also be implanted at the dilated location in order to preserve the dilation. However, because of the stiff, mineral nature of vascular calcifications, angioplasty balloons may not effectively dilate a vessel at the site of a calcification and may even burst when taken to high pressure at these calcifications. Therefore, in these cases, the calcified lesion must first be treated to “crack” the calcified areas.

[0004] The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded as subject matter by which the scope of the disclosure is to be bound.SUMMARY

[0005] Disclosed herein is a vessel compliance estimation system. The vessel compliance estimation system has particular, but not exclusive, utility for detecting the fracturing of calcified vascular stenoses. An ultrasonic endoflator attaches to an intravascular balloon catheter that can be inserted into the vasculature of a patient. When the balloon is positioned at a calcified (hardened) location within a vessel, the ultrasonic can slowly expand the balloon until it is in contact with the vessel walls. The ultrasonic endoflator can then briefly and rapidly inflate the balloon by a small additional amount, to generate a hydraulic shock that can fracture the calcification. Compliance of the vessel wall can be computed as a function of the volume and pressure of the balloon. Thus, the vessel compliance estimation system includes sensors for measuring or estimating both pressure and volume, as well as a processor for calculating compliance. Calcified vessel walls exhibit low compliance, whereas when the calcium has been successfully fractured, the compliance will suddenly increase. This increase in compliance can be used to both detect and quantify the cracking of a calcified stenosis, and thus determine when the calcification is sufficiently fractured to allow the vessel to be dilated and, if necessary, stented.

[0006] A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions. One general aspect includes an apparatus which includes an endoflator configured for fluid communication with an intravascular catheter and configured to inflate a balloon of the intravascular catheter with a fluid. The apparatus also includes a processor. At least one of the intravascular catheter or the endoflator may include a first sensor configured to provide a first output, where the processor is configured to: compute a compliance of the balloon based on the first output of the first sensor; and provide, to a display in communication with the processor, a visual representation associated with the compliance. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0007] Implementations may include one or more of the following features. The apparatus may include the intravascular catheter. At least one of the intravascular catheter orthe endoflator may include a second sensor configured to provide a second output, where the processor is configured to compute the compliance based on the second output of the second sensor. The first output may be indicative of a pressure inside the balloon, and the second output may be indicative of a volume of the fluid inside the balloon. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0008] One general aspect includes a device for measuring compliance of a balloon of a balloon catheter. The device includes a processor; a first sensor configured for communication with the processor; and a second sensor configured for communication with the processor, where the processor is configured to compute, based on an output of the first sensor and an output of the second sensor, a compliance of a balloon on a balloon catheter positioned proximate to the calcified stenosis of a blood vessel, where the compliance is indicative of a degree of fracturing of the calcified stenosis by the balloon. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0009] Implementations may include one or more of the following features. The device may include a display, where the processor is configured to display, on the display, a graph or alphanumeric output indicative of the compliance of the balloon or a time history thereof. In some aspects, the first sensor is a first electrode; the second sensor is a second electrode, and the processor is configured to compute the compliance of the balloon based on an impedance of tissue in contact with the first electrode and the second electrode. In some aspects, the first sensor is a pressure sensor in fluid communication with the balloon and in electronic communication with the processor, such that a pressure measurement from the pressure sensor is indicative of a pressure inside the balloon, the second sensor is a position sensor, flow sensor, or volume sensor in fluid communication with the balloon and in electronic communication with the processor, such that a position, flow, or volume measurement from the position sensor, flow sensor, or volume sensor is indicative of a volume of fluid inside the balloon, and the processor is configured to compute the compliance of the balloon based on the pressure inside the balloon and the volume of fluid inside the balloon. In some aspects, when the balloon is positioned within a calcified stenosis of a blood vessel of a patient, the computed compliance is indicative of a degree of fracturing of the calcified stenosis. The device may include an electromechanical endoflator configured to cyclically inflate and deflate the balloon with an electromechanical actuator to generate hydraulic shockwavesconfigured to fracture the calcified stenosis. The electromechanical actuator may include the pressure sensor. The electromechanical actuator may include the position sensor, flow sensor, or volume sensor. The pressure measurement may be a dynamic pressure measurement. The device may include a manual endoflator configured to inflate the balloon to generate hydraulic force configured to fracture the calcified stenosis. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0010] One general aspect includes a system for measuring compliance. The system includes a processor; a balloon catheter that includes a balloon; an endoflator configured for fluid communication with the balloon catheter, where the endoflator is configured to provide fluid to the balloon to inflate the balloon, where the balloon catheter or the endoflator may include: a pressure sensor in fluid communication with the balloon and in electronic communication with the processor, such that a pressure measurement from the pressure sensor is indicative of a pressure inside the balloon; and a position sensor, flow sensor, or volume sensor in fluid communication with the balloon and in electronic communication with the processor, such that a position, flow, or volume measurement from the position sensor, flow sensor, or volume sensor is indicative of a volume of fluid inside the balloon. The processor is configured to compute the compliance of the balloon based on the pressure inside the balloon and the volume of fluid inside the balloon. The system also includes a display, where the processor is configured to display, on the display, a graph or alphanumeric output indicative of the compliance of the balloon, where, when the balloon is positioned within a calcified stenosis of a blood vessel of a patient, the computed compliance is indicative of a degree of fracturing of the calcified stenosis. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0011] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the vessel compliance estimation system, as defined in the claims, is provided in the following written description of various aspects of the disclosure and illustrated in the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Illustrative aspects of the present disclosure will be described with reference to the accompanying drawings, of which:

[0013] Figure l is a schematic, diagrammatic representation of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0014] Figure l is a diagrammatic, perspective view of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0015] Figure 3A is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0016] Figure 3B is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0017] Figure 3C is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0018] Figure 4A is a diagrammatic, perspective view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0019] Figure 4B is a diagrammatic, perspective view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0020] Figure 5A is an example pressure vs. time graph of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0021] Figure 5B is an example pressure vs. time graph of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0022] Figure 6 is a schematic, diagrammatic representation of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0023] Figure 7A is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0024] Figure 7B is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0025] Figure 7C is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0026] Figure 7D is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0027] Figure 8 is a schematic, diagrammatic, side cross-sectional view of a blood vessel, in accordance with at least one aspect of the present disclosure.

[0028] Figure 9 is a schematic, diagrammatic, side cross-sectional view of a blood vessel, in accordance with at least one aspect of the present disclosure.

[0029] Figure 10 is a schematic, diagrammatic, side cross-sectional view of a blood vessel, in accordance with at least one aspect of the present disclosure.

[0030] Figure 11 is an example time sequence for a calcified stenosis treatment process using the vessel compliance estimation system, in accordance with at least one aspect of the present disclosure.

[0031] Figure 12 is an example screen display for a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure.

[0032] Figure 13 is a schematic, diagrammatic representation, in flow diagram form, of an example vessel dilation estimation method, in accordance with at least one aspect of the present disclosure.

[0033] Figure 14 is a schematic, diagrammatic representation, in flow diagram form, of an example vessel dilation estimation method, in accordance with at least one aspect of the present disclosure.

[0034] Figure 15 is a schematic, diagrammatic representation of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0035] Figure 16A is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0036] Figure 16B is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0037] Figure 16C is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0038] Figure 17 is a schematic, diagrammatic representation, in flow diagram form, of an example vessel dilation estimation method, in accordance with at least one aspect of the present disclosure.

[0039] Figure 18 is a frequency vs. compliance curve, in accordance with at least one aspect of the present disclosure.

[0040] Figure 19 is a schematic, diagrammatic representation of an example balloon angioplasty system with manual endoflator, in accordance with at least one aspect of the present disclosure.

[0041] Figure 20 is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system with manual endoflator, in accordance with at least one aspect of the present disclosure.

[0042] Figure 21 is a schematic, diagrammatic representation of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure.

[0043] Figure 22A is a schematic, diagrammatic representation of at least a portion of an example balloon angioplasty system which incorporates a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure.

[0044] Figure 22B is a schematic, diagrammatic representation of at least a portion of an example balloon angioplasty system which incorporates a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure.

[0045] Figure 22C is a schematic, diagrammatic representation of at least a portion of an example balloon angioplasty system which incorporates a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure.

[0046] Figure 23 is a schematic diagram of a processor circuit, according to at least one aspect of the present disclosure.DETAILED DESCRIPTION

[0047] The present disclosure provides a vessel compliance estimation system for use with intravascular balloon catheters. When treating severely calcified lesions various treatment devices can be used, each having their advantages and drawbacks. Several types of intravascular devices have been developed with the aim to modify the calcium during percutaneous coronary interventions (PCIs). This so-called “vessel preparation” is often needed to achieve adequate stent expansion and apposition. Examples of such devices include: balloon-based devices (e.g. non-compliant balloon, high-pressure non-compliant balloons, cutting- and scoring balloons, atherectomy (rotational atherectomy, laser atherectomy), and intravascular lithotripsy (shockwave).

[0048] An ultrasound-based lithotripsy device can use hydraulic pressure waves from an electromechanical (e.g., ultrasonic) endoflator to achieve a similar effect as intravascular lithotripsy (IVL). Aspects of an electromechanical endoflator are described in U.S. Provisional Application No. 63 / 446,999, filed February 20, 2023, titled “Electromechanical Endoflator for Balloon Catheter”, which is incorporated by reference herein in its entirety. An ultrasonic endoflator is an ultrasound-based lithotripsy device that produces hydraulic pressure waves to crack the calcified lesions. When used in combination with a balloon catheter (e.g., a scoring balloon, cutting balloon, etc.), the ultrasonic endoflator can first crack the calcification and then expand the balloon to dilate the vessel, such that the calcification does not prohibit the opening of the stent.

[0049] An ultrasonic endoflator attaches to a balloon catheter that can be inserted into the vasculature of a patient. When the balloon is positioned at a calcified (hardened) location within a vessel, the ultrasonic can slowly expand the balloon until it is in contact with the vessel walls. The ultrasonic endoflator can then briefly and rapidly inflate the balloon by a small additional amount, to generate a hydraulic shock that can subject the calcification to fatigue fracture. This expansion can be singular or cyclic, depending on the needs of the situation. Calcifications tend to be well rooted into soft tissue, or even completely encapsulated by soft tissue, such that fracturing the calcification does not generally release the calcified material into the bloodstream. The fracturing process may for example be analogous to breaking up a bag of frozen-together ice cubes, without opening the bag. However, the ultrasonic endoflator does not provide direct feedback on the treatment of the calcified lesion, such as whether it is sufficiently “cracked” to permit dilation of the vessel and expansion of a stent.

[0050] The vessel compliance estimation system provides an ability to detect and quantify the fracturing of calcified stenoses, to facilitate treatment of the lesion in an optimal and efficient way. The vessel compliance estimation system may for example include sensors integrated into the endoflator and / or the balloon, as well as computations (e.g., computer software) to enable mathematical analysis of static and dynamic ultrasonic pressure measurements and / or electrical impedance spectroscopy measurements. Since no electrodes are needed inside the balloon, a smaller diameter (3F rather than 3.5F as in IVL) can be used, providing a better deliverability. The unique feature of this device is that it is a specialty balloon (scoring) and lithotripsy device in a single device, which means that dilation and vessel preparation can be done with the same device, along with real-time feedback on the progress of the treatment.

[0051] Vessel compliance - the compliance of an angioplasty balloon in contact with the walls of a blood vessel is proportional to, and thus a proxy for, the compliance of the vessel itself. It is known that calcified lesions are stiffer (i.e. lower compliance) than non-calcified lesions, especially in case of concentrically calcified lesions. Higher stiffness, means that more pressure change is needed to achieve a certain change in volume (hence diameter, in case of a circular-shaped vessel). Compliance (C) is calculated using the following equation, where AV is the change in volume, and AP is the change in pressure:C=AV / AP (EQN 1)

[0052] However, in blood vessels, the compliance decreases as pressure increases, because the blood vessel wall is a heterogeneous tissue. Therefore, compliance decreases at higher pressures and volumes (i.e., vessels become "stiffer" at higher pressures and volumes) In other words: increasingly higher pressure is needed to further expand the vessel. Calcified coronary arteries have even further reduced vessel compliance, thus prohibiting stent delivery, while also reducing the ability of implanted stents to expand and appose as required. Calcified vessels have abnormally low compliance due to solid calcium in the vessel wall.

[0053] The ultrasonic endoflator includes an external device (endoflator) and balloon introduced by an intraluminal / intravascular catheter. The device is intended to provide ultrasound-based lithotripsy from an intraluminal / intravascular balloon (e.g., a scoring balloon, an angioplasty balloon, etc.). As the calcium in the vessel wall is fractured or cracked by the ultrasonic shockwaves, the vessel compliance is increased. Unfortunately, aswith other calcium modification methods, it’s difficult for the physician to estimate whether and when enough cracking has taken place and the desired result has been achieved.

[0054] Vessel compliance estimation system is based on events like vessel expansion by balloon inflation and calcium modification being directly linked to change in compliance and impedance of the vessel. By measuring either of these signals over time, feedback can be provided to the physician about the progress of the treatment. Optionally, an algorithm via a look-up table or Al-based approach can be used to recognize the signal pattem(s) to predict how to proceed.

[0055] In a first aspect, monitoring of vessel preparation (e.g., calcium cracking) is by estimation of vessel compliance, by measuring static pressure and volume in the balloon. In this aspect, vessel compliances are calculated over time by combining measurements of static pressure and volume / flow in / towards the balloon inflation device, where static pressure is the pressure as that is generated by inflating the balloon in a gradual way and subsequent changes in pressure due to tissue response (e.g. pressure drop due to cracking of calcium). Artificial, dynamically generated pressure fluctuations may not be considered as part of this calculation.

[0056] Combining the changes in volume (V) in the balloon and pressure (P) in the balloon, the compliance of the tissue can be derived during inflation of the balloon. As the vessel wall is a heterogenous tissue, compliance will change depending on the pressure and volume. This will provide a AP / AV curve that can be used to type / grade the lesion (optionally with artificial intelligence (Al) or machine learning (ML) assistance). This aspect does not take into account the additional information that can be derived during application of the dynamic oscillating pressure wave that is generated by the ultrasonic endoflator.

[0057] In some aspects, the compliance referred to herein can be the compliance of the balloon directly and the compliance of the blood vessel indirectly. In that regard, the volume and / or the pressure of the fluid inside the balloon can be used to calculate the compliance of the balloon directly. The compliance of the vessel can be equal to or proportional to the compliance of the balloon. In some aspects, any difference between the compliance of the balloon and the compliance of the vessel can be considered negligible when the balloon is being inflated and pressing against the wall(s) of the blood vessel.

[0058] The endoflator uses a liquid to inflate the balloon. During inflation and lesion modification , several distinct phases can be identified. During initial inflation, the balloon will increase in size until it fills the lumen within the lesion; during this phase, the pressure will be as high as needed to expand the balloon only. During further inflation, the balloon encounters increasing resistance from the lesion / vessel. The pressure needed to expand theballoon and lesion is directly related to the compliance of the vessel, and becomes increasingly higher, especially in highly calcified lesions. If the (static) pressure in the balloon is sufficiently high to fracture the calcifications in the lesions, there will be a sudden drop in pressure within the balloon accompanied by an increase of volume of the balloon. For further inflation of the balloon (higher volume) less pressure is needed than before calcium fracturing due to lower compliance.

[0059] A different but similar aspect uses a variation of oscillator frequencies to get a curve / number of points for each moment in time. Preferably an algorithm is used in combination with a lookup table or database to provide lesion characterization.Understanding lesion morphology is pivotal in choosing the proper vessel preparation tool. A database and Al can be employed for lesion quantification and prediction on what vessel prep devices to use to achieve an optimal outcome. The relationship between compliance and frequency, like the compliance itself, can be indicative of calcium fracture.

[0060] Vessel electrical impedance - tissues can be characterized by their impedance as a function of the frequency of the applied electrical field, due to the difference in permittivity and electrical conductivity. On the website: https: / / itis.swiss / virtual-population / tissue- properties / database / dielectric-properties / the dielectric properties of various tissue is listed, including blood and blood vessel walls. Such tissues show a clear difference in permittivity and conductivity properties (hence also in impedance properties), and can therefore be differentiated based on impedance measurements. Furthermore, it is expected that when calcified lesions in the vessel wall are present, that this will be visible in difference in the impedance measurements and especially in the conductivity properties.

[0061] Thus, in another aspect, electrodes are added to the outside of the ultrasonic endoflator balloon to enable impedance spectroscopy. When measuring the impedance as function of the frequency between the various electrodes, changes in the impedance can be determined. The impedance is measured between the various electrode combination such that the probing area covers a significant portion of the vessel wall. These changes in impedance during treatment are for instance caused when solid calcium parts are cracked into smaller pieces, with a result that conductive intracellular fluid can enter in between the cracked calcium fragments, thus altering the conductivity and permittivity of the vessel wall. When continuously measuring the impedance as function of the frequency, these changes can be measured and used to monitor the treatment progression.

[0062] Still other aspects do not require an ultrasonic endoflator, and can instead employ sensors in adjunct to simpler devices like a non-compliant balloon. The intent here is to usethe ultrasonic pressure waves of the endoflator to do lesion characterization, rather than using the sensor as monitoring / feedback add-on to an ultrasonic endoflator device or another device for lithotripsy. Non-compliant balloons are typically used as a first-line treatment before physicians escalate to more advanced (and riskier) devices and tools. One issue here is that the decision tree on what tools to use is mainly based on simplicity, safety profile and costs, and less on the calcium characteristics of the lesion. This often means a trial -and-error approach, and limited instance of succeeding on the first try. Having a sensor that characterizes the lesion during inflation of the balloon is therefore beneficial. Calcium fracturing can be characterized either by determining the changes in vessel compliance during simple volume-pressure measurements, or by adding a dynamic pressure generator-sensor combination to do more advanced characterization. All previously described aspects can be applied to simpler balloon-based devices without the ultrasonic endoflator working mechanism.

[0063] The present disclosure aids substantially in the treatment of calcified stenoses, by improving a clinician’s ability to detect and quantify fracturing of the calcification. Using sensors and processors in communication with an endoflator and / or balloon catheter, the vessel compliance estimation system disclosed herein provides a practical ability to know when a blood vessel can be dilated and stented, while minimizing the risk of rupturing the balloon or damaging the vessel. This improved angioplasty technique repeatably transforms a solid calcification into a number of tissue-bound fragments that can be safely dilated and stented, without the normally routine need to ablate or cut the calcified tissue. This unconventional approach improves the functioning of the balloon angioplasty system, by providing clear guidance as to when the calcification fracturing process is complete, so that vessel dilation and stenting can commence.

[0064] The vessel compliance estimation system may be controlled through an automated process at least partially viewable on a display and executing on a processor that accepts user inputs from a keyboard, mouse, or touchscreen interface. In that regard, the control process performs certain specific operations in response to different inputs or selections made at different times. Certain structures, functions, and operations of the processor, display, sensors, and user input systems are known in the art, while others are recited herein to enable novel features or aspects of the present disclosure with particularity.

[0065] These descriptions are provided for exemplary purposes only and should not be considered to limit the scope of the vessel compliance estimation system. Certain featuresmay be added, removed, or modified without departing from the spirit of the claimed subject matter.

[0066] For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the aspects illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and / or steps described with respect to one aspect may be combined with the features, components, and / or steps described with respect to other aspects of the present disclosure. For the sake of brevity, however, the numerous iterations of these combinations will not be described separately.

[0067] Figure l is a schematic, diagrammatic representation of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. The balloon angioplasty system 100 includes a console or workstation 110, an electromechanical endoflator 120, and an intravascular balloon catheter 130. In an example, the console 110 includes a housing 118 that encloses a processor circuit 112 in communication with an electrical power source (e.g., a current source and / or voltage source) 114 and a display 116. In an example, the electromechanical endoflator 120 includes a housing 190 and a manual actuator 160 that permits a clinician to increase the static pressure of a fluid chamber 180 that is in fluid communication with the balloon catheter 130 via a fluid line 195. The electromechanical endoflator 120 also includes an electromechanical actuator 170 which receives power from the electrical power source 114 via a cable 150. Similar to the manual actuator 160, the electromechanical actuator 170 can provide a transient pressure, additive to the static pressure of the fluid chamber 180 and thus communicated to the balloon catheter 130 via the fluid line 195. In some instances, the fluid line 195 and the balloon catheter 130 are separate components. In some instances, the fluid line 195 and the balloon catheter 130 are the same component. For example, the fluid line 195 can be a portion of a length of the balloon catheter 130 (e.g., a portion of a length of the catheter body 135).

[0068] In an example, the balloon catheter 130 includes a catheter body or flexible elongate member 135 in fluid communication with a balloon 140. The catheter 130 can be referred to as an intravascular catheter, balloon catheter, intravascular balloon catheter, etc.

[0069] It is noted that block diagrams are provided herein for exemplary purposes; a person of ordinary skill in the art will recognize myriad variations that nonetheless fall within the scope of the present disclosure. For example, block diagrams may show a particular arrangement of components, modules, services, steps, processes, or layers, resulting in a particular flow of data and / or material. It is understood that some aspects of the systems disclosed herein may include additional components, that some components shown may be absent from some aspects, and that the arrangement of components may be different than shown, resulting in different data and material flows while still performing the methods described herein.

[0070] Before continuing, it should be noted that the examples described above are provided for purposes of illustration and are not intended to be limiting. Other devices and / or device configurations may be utilized to carry out the operations described herein.

[0071] Figure 2 is a diagrammatic, perspective view of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the console 110, console housing 118, electrical cable 150, electromechanical endoflator 120, endoflator housing 190, manual actuator or plunger 160, electromechanical actuator 170, fluid chamber 180, fluid line 195, balloon catheter 130, and balloon 140.

[0072] The manual actuator or plunger 160 can be operated by a clinician to increase or decrease the static pressure in the fluid chamber 180. In an example, depressing the plunger 160 increases the static pressure, and withdrawing the plunger 160 decreases the static pressure. Other types of manual actuator 160 can be used instead or in addition, and the manual actuator 160 may include a screw or lock 260 to prevent the manual actuator 160 from moving, and thus to prevent unwanted changes in the static pressure of the fluid chamber 180.

[0073] The electromechanical actuator 170 may for example be a piston, a solenoid, a block of piezoelectric material, or otherwise. When the electromechanical actuator 170 receives transient or time-varying power through the cable 150, the electromechanical actuator 170 temporarily expands or advances such that the volume of a transient pressure chamber 210 is increased, and thus a transient pressure is generated that is additive to the static pressure of the fluid chamber 180. The transient pressure chamber 210 is in fluid communication with the fluid chamber 180, which is in fluid communication with the balloon catheter 130 via the fluid line 195. At any given moment, the total pressure in the fluid chamber 180 (e.g., the sum of the static pressure and transient pressure) may be shown on agauge 220, which may for example be an analog, digital gauge, or graphical. Depending on the implementation, the transient pressure may be shown on the display 116 instead or in addition, or may be represented by an audio tone, a haptic feedback such as a vibration, a color, or otherwise.

[0074] The balloon catheter 130 includes a catheter body 135, which includes a portion 234 that remains outside the patient’s body, and a portion 236 that is inserted into the patient’s vasculature or other body lumen. A proximal portion of the balloon catheter 130 is coupled (e.g., removably coupled) to a distal portion of the electromechanical endoflator 120. A distal portion of the balloon catheter 130 (e.g., a distal portion of the catheter body 135) includes a tip assembly 240 and a balloon 140. The static diameter of the balloon 140 is a function of the static pressure. However, the balloon can also experience a transient expansion, contraction, or vibration based on changes in the transient pressure. The frequency or duty cycle of a vibration may for example be between 10 and 100 Hz, although in some cases it may be between 1 and 10,000 Hz.

[0075] Figure 3A is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, and catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140. A proximal portion of the catheter body 135 is coupled (e.g., removably coupled) to the distal portion of the electromechanical endoflator 120 to establish fluid communication between the electromechanical endoflator 120 and the balloon catheter 130. A fluid 310 is contained within the fluid chamber 180, transient pressure chamber 210, catheter lumen 330, and balloon 140. The fluid 310 may for example be a mixture of saline solution and an x-ray or ultrasound contrast dye, in order to make the balloon 140 visible in an X-ray or ultrasound angiography image. An increase or decrease in the pressure of the fluid 310 causes the fluid 310 to flow into or out of an interior volume 340 of the balloon 140 via one or more inflation ports 345.

[0076] The fluid chamber 180 and the transient pressure chamber 210 can be two subvolumes of an individual volume (e.g., two portions of the individual volume). For example, the housing 190 of the electromechanical endoflator 120 can define the individual volume, which includes the fluid chamber 180 and the transient pressure chamber 210. For example, the fluid chamber 180 and the transient pressure chamber 210 are in fluid communication with one another within the housing 190 of the electromechanical endoflator 120.

[0077] In the example shown in Figure 3 A, the manual actuator 160 is depressed by a distance Pl, while the electromechanical actuator 170 has a thickness Tl, which results in a volume V3 A and a pressure P3 A of the fluid 310, and thus a diameter DI for the balloon 140. It is noted that, depending on the magnitude of the pressure change and the material from which the balloon is made, this diameter change can be quite small (e.g., less than one millimeter in some cases), while still producing the desirable effects described herein.

[0078] Figure 3B is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140, fluid 310, balloon interior volume 340, and inflation ports 345.

[0079] In the example shown in Figure 3B, the manual actuator 160 is depressed by a distance P2, which is larger than the distance Pl of Figure 3 A, while the electromechanical actuator 170 has the same thickness Tl . Since the fluid 310 is approximately incompressible, the resulting volume V3B of the fluid 310 must be approximately the same as the volume V3A of Figure 1, while the pressure P3B (e.g., the static pressure) of the fluid 310 may increase proportionally with the difference between P2 and Pl . In order to keep the volume constant, the balloon 140 expands to a diameter D2, larger than the diameter DI of Figure 3 A, through flow of the fluid 310 into the balloon interior 340 via the inflation ports 345.

[0080] Figure 3C is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, electromechanical actuator 170, catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140, fluid 310, balloon interior volume 340, and inflation ports 345.

[0081] In the example shown in Figure 3C, the manual actuator 160 is still depressed by a distance P2, but the piezoelectric electromechanical actuator 170 has (e.g., under the influence of a voltage) expanded to a thickness T2, which is larger than the thickness Tl of Figures 3 A and 3B. Since the fluid 310 is approximately incompressible, the resulting volume V3C of the fluid 310 must be approximately the same as the volumes V3A of Figure 3 A and V3B of Figure 3B, while the pressure P3C of the fluid 310 may increase proportionally with the difference between T2 and Tl. In order to keep the volume constant,the balloon 140 expands to a diameter D3 (larger than the diameter D2 of Figure 3B), through flow of the fluid 310 into the balloon interior 340 via the inflation ports 345.

[0082] However, the thickness increase of the piezoelectric electromechanical actuator 170 is transient, such that when the voltage is removed, the thickness T2 may return to a baseline thickness Tl, and the pressure P3C may return to the static pressure P3B, through flow of the fluid 310 out of the balloon interior 340 and into the catheter interior 330 via the inflation ports 345. Thus, the balloon 140 may return to a diameter D2.

[0083] Figure 4A is a diagrammatic, perspective view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator, in accordance with at least one aspect of the present disclosure. Visible are the catheter body 135, balloon 140, and tip assembly 240. In the example shown in Figure 4A, the balloon 140 is positioned inside / within a blood vessel (e.g., a lumen of the blood vessel) or other body lumen 410 (e.g., longitudinally co-located with, adjacent to, and / or otherwise proximate to a calcification 430 attached to the vessel wall 420 of the blood vessel or other body lumen 410). Because the calcification 410 has a hard, bony or mineral-like consistency, simply expanding the balloon 140 (e.g., by increasing the static pressure via the manual actuator) may not dilate the vessel 410.

[0084] Figure 4B is a diagrammatic, perspective view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator, in accordance with at least one aspect of the present disclosure. Visible are the catheter body 135, balloon 140, and tip assembly 240. In the example shown in Figure 4B, the balloon 140 is positioned inside / within a blood vessel (e.g., a lumen of the blood vessel) or other body lumen 410 (e.g., longitudinally co-located with, adjacent to, and / or otherwise proximate to a calcification attached to the vessel wall 420 of the blood vessel or other body lumen 410). After delivery of a transient or periodic (e.g., sinusoidal) pressure increase or “shock” delivered by the electromechanical endoflator, the calcification 430 of Figure 4A has been fractured (e.g., fatigue fractured) into a plurality of bound, calcified fragments 440. Because the calcified fragments 440 have a gravelly or sandy consistency, expanding the balloon 140 (e.g., by increasing the static pressure via the manual actuator) may now be sufficient to dilate the vessel 410 (e.g., for subsequent stenting).

[0085] Depending on the implementation, the balloon angioplasty system 100 with electromechanical endoflator may be used with custom angioplasty balloons specifically designed for use with the electromechanical endoflator, or may be used with any of a varietyof off-the-shelf angioplasty balloon types, including compliant balloons, non-compliant balloons, cutting balloons, and otherwise.

[0086] Figure 5A is an example pressure vs. time graph 510 of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure. The Y-axis of the graph 510 shows pressure in atmospheres inside the endoflator (e.g., inside the fluid chamber 180 of Figures 1-3B), while the X-axis of the graph 510 shows time in seconds. Visible are an average or baseline or static pressure 530, and a time-variant (e.g., sinusoidal) pressure 520 having an amplitude A and a period P. In an example, the average or baseline or static pressure 530 is determined by a position of the manual actuator 160 (see Figs. 1-3B), while the amplitude A and period P of the time-variant pressure 520 are determined by the expansion and contraction of the piezoelectric electromechanical actuator 170 (see Figs. 1-3B) under the influence of the electrical power source 114 controlled by the processor circuit 112 (see Fig. 1). In an example, the console 110 (see Fig. 1) may include a user interface (whether analog or digital) to enable to user to select at least one of the amplitude A or the period P.

[0087] Figure 5B is an example pressure vs. time graph 540 of an example balloon angioplasty system with electromechanical endoflator, in accordance with at least one aspect of the present disclosure. The Y-axis of the graph 540 shows pressure in atmospheres inside the balloon 140 (see Figures 1-3B), while the X-axis of the graph 540 shows time in seconds. Visible are an average or baseline or static pressure 560, and a time-variant (e.g., sinusoidal) pressure 550, which may for example have a similar period as the curve 520 of Figure 5A, and may have a slightly smaller amplitude due to friction losses in the system. Because fluid takes a certain amount of time to travel, e.g., from the transient pressure chamber 210 to the balloon interior 340 (see Figs. 3 A-3C), the curve 550 is lagged or time-shifted with respect to the curve 520 of Figure 5 A, by an amount AT.

[0088] It is noted that other pressure-vs.-time curves and other types of pressure-vs.-time curves may occur instead of or in addition to those shown herein. It is further noted that other types of endoflators and / or other calcification fracture methods may be used instead of or in addition to those described herein. Various types of balloons may be used, including high-compliance balloons, low-compliance balloons, cutting balloons, and otherwise. All such variations fall explicitly within the scope of the present disclosure.

[0089] Figure 6 is a schematic, diagrammatic representation of an example balloon angioplasty system 600 with electromechanical endoflator 120, in accordance with at leastone aspect of the present disclosure. The balloon angioplasty system 600 includes a console or workstation 110, an electromechanical endoflator 120, and a balloon catheter 130, which includes a catheter body or flexible elongate member 135 in fluid communication with a balloon 140.

[0090] In an example, the console 110 includes a housing 118 that encloses a processor circuit 112 in communication with an electrical power source (e.g., a current source and / or voltage source) 114 and a display 116. In an example, the electromechanical endoflator 120 includes a housing 190 and a manual actuator 160 that permits a clinician to increase the static pressure of a fluid chamber 180 that is in fluid communication with the balloon catheter 130 via a fluid line 195. The electromechanical endoflator 120 also includes an electromechanical actuator 170 which receives power from the electrical power source 114 via a cable 150. Similar to the manual actuator 160, the electromechanical actuator 170 can provide a transient pressure, additive to the static pressure of the fluid chamber 180 and thus communicated to the balloon catheter 130 via the fluid line 195.

[0091] In the example shown in Figure 6, the electromechanical endoflator 120 also includes any of a pressure sensor 610, flow sensor 620, and an encoder or position sensor 630 in communication with the console 110 (e.g., with the processor circuit 112). Using readings from the pressure sensor 610, the processor circuit 112 can determine, whether directly or indirectly, the pressure of the fluid within the balloon 140. Using readings from the flow sensor 620, the processor circuit 112 can determine, whether directly or indirectly, the volume of fluid that has been delivered into the balloon 140. Using readings from the position sensor 630, the processor circuit 112 can determine the position of the manual actuator 160, and thus the volume of fluid that has been delivered into the balloon 140.These pressure and volume values can then be used to calculate the compliance of the balloon 140 as described above.

[0092] The balloon angioplasty system 600 may also include an electrocardiogram 640 in communication with the console (e.g., with the processor circuit 112). Since blood pressure varies with heartbeat, the pressure inside the balloon is also variable. Thus, it may be desirable for the processor circuit to calculate the compliance using pressure and volume values captured at the same point in every heartbeat cycle. In other aspects, the heartbeat cycle may be determined from the pressure readings and / or flow readings themselves.

[0093] Figure 7A is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120,manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140, fluid 310, balloon interior volume 340, and inflation ports 345.

[0094] In the example shown in Figure 7 A, the position sensor 630 measures the position of the manual actuator 160, which is proportional to the volume of fluid 310 pushed into the balloon 140, and thus also proportional to the volume of the balloon 140 or change in the volume of the balloon 140.

[0095] Figure 7B is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140, fluid 310, balloon interior volume 340, and inflation ports 345.

[0096] In the example shown in Figure 7B, the flow sensor 620 measures a flowrate of the fluid 310 toward the balloon 140. The time integral of flowrate is proportional to the volume of fluid 310 pushed into the balloon 140, and thus also proportional to the volume of the balloon 140 or change in the volume of the balloon 140.

[0097] Figure 7C is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140, fluid 310, balloon interior volume 340, and inflation ports 345.

[0098] In the example shown in Figure 7C, the pressure sensor 610 measures the pressure of the fluid 310 in the fluid chamber 180, which is related and proportional to the pressure of the fluid 310 in the balloon 140, while the flow sensor 620 measured the flowrate of the fluid 310 and thus the volume of the balloon 140 as described above. The pressure and volume values can be used to compute an absolute compliance for the balloon, or changes in pressure and volume can be used to compute a change or rate of change of the compliance of the balloon 140.

[0099] Figure 7D is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectricelectromechanical actuator 170, catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140, fluid 310, balloon interior volume 340, and inflation ports 345.

[0100] In the example shown in Figure 7D, the pressure sensor 610 measures the pressure of the fluid 310 in in the balloon 140, while the flow sensor 620 measured the flowrate of the fluid 310 in the catheter lumen 330 and thus the volume of the balloon 140 as described above. The pressure and volume values can be used to compute an absolute compliance for the balloon, or changes in pressure and volume can be used to compute a change or rate of change of the compliance of the balloon 140.

[0101] It is noted that instead of a position sensor or flow sensor, the vessel compliance estimation system could directly measure the volume of the balloon, e.g., with an imaging sensor, or other volume sensor capable of providing information indicative of the volume of the balloon.

[0102] Figure 8 is a schematic, diagrammatic, side cross-sectional view of a blood vessel 410, in accordance with at least one aspect of the present disclosure. The blood vessel 410 includes a vessel wall 420, tissue interface 810, and lumen 830. In the example shown in Figure 8, the blood vessel 410 also includes a calcified stenosis or calcification 430. A catheter body 135 and balloon 140 have been positioned within the blood vessel 410 such that the balloon 140 is longitudinally aligned with the calcified stenosis. In this configuration, pumping fluid into the balloon 140 will result in a relatively large volume change for a relatively small change in pressure, indicating that the balloon 140 has a high compliance and is not apposed.

[0103] Figure 9 is a schematic, diagrammatic, side cross-sectional view of a blood vessel 410, in accordance with at least one aspect of the present disclosure. Visible are the blood vessel 410, vessel wall 420, tissue interface 810, lumen 830, calcification 430, catheter body 135, and balloon. In the example shown in Figure 9, the balloon 140 has been expanded until it is in contact with the calcification 430. However, because the calcification 430 has a hard, bony or mineral-like consistency, simply expanding the balloon 140 (e.g., by increasing the static pressure via the manual actuator) may not dilate the vessel 410. In this configuration, because the calcification resists expansion, pumping additional fluid into the balloon 140 will result in a relatively small volume change for a relatively large change in pressure, indicating a significantly reduced compliance for the balloon 140. This sudden reduction in compliance may be used as an indicator that the balloon 140 is now apposed (e.g., in contact with the calcification). Although not shown in this schematic drawing, it is understood that the vessel wall 420 can expand outward as the balloon is inflated.

[0104] Figure 10 is a schematic, diagrammatic, side cross-sectional view of a blood vessel 410, in accordance with at least one aspect of the present disclosure. Visible are the blood vessel 410, vessel wall 420, tissue interface 810, lumen 830, calcification 430, catheter body 135, and balloon. In the example shown in Figure 10, the balloon 140 has been expanded, vibrated, shocked, or combinations thereof, until it has converted the calcification 430 into a cracked, fractured, or fragmented calcification 440. Because the cracked or fractured calcification 440 has a gravel-like consistency, expanding the balloon 140 (e.g., by increasing the static pressure via the manual actuator) may now result in dilation of the vessel 410. Thus, pumping additional fluid into the balloon 140 will result in a relatively large volume change for a relatively small change in pressure, indicating an increased compliance for the balloon. This increase in compliance (whether sudden or gradual) may be used as an indicator that the calcification 430 has been successfully fractured, so that further treatment (e.g., dilation and stenting) can occur.

[0105] Figure 11 is an example time sequence 1100 for a calcified stenosis treatment process using the vessel compliance estimation system, in accordance with at least one aspect of the present disclosure.

[0106] In step 1110, the time sequence 1100 includes pumping fluid into the balloon to increase its volume. Balloon pressure and compliance will remain relatively stable during this time, indicating that the balloon is inflating but not yet apposed, and thus that inflation should continue.

[0107] In step 1120, the sensors detect a substantial drop in balloon compliance, indicating that the balloon is apposed. At this point, the current values of balloon volume, pressure, and compliance can be taken as baseline values. Inflation should continue.

[0108] In step 1130, the compliance of the balloon slowly increases, indicating that the vessel diameter is increasing.

[0109] In step 1140, the sensors detect a sudden increase in the volume and compliance of the balloon, indicating that the calcification has begun to crack, and thus the vessel diameter is continuing to increase.

[0110] In step 1150, the sensors detect a sudden increase in the volume and compliance of the balloon, indicating that the calcification has been successfully fractured.

[0111] In step 1160, the sensors detect that the balloon is continuing to increase in volume, but with a relatively high, relatively stable compliance. This condition indicates that the fracturing of the calcification is sufficient that further treatment (e.g., vessel dilation and stenting) can take place.

[0112] This time sequence 1100 describes a relatively simple calcification fracturing by manual inflation of the balloon. It is understood that similar sequences may involve vibration, acoustic shock, scoring, or other treatment options to fracture the calcification. In such sequences, the compliance of the balloon can similarly be used to detect and quantify the fracturing of the calcification.

[0113] To provide actionable feedback to the physician, several features can be employed. In some aspects, the pressure signal is linked to a measure of volume (e.g. volume in the endoflator piston) or flow (e.g. through the catheter) to get an estimate for compliance. In some aspects, the signal is calibrated / corrected for the system compliance, so that the estimated vessel compliance will not be compounded by the compliance of the balloon, catheter and endoflator itself (as these components will never be 100% stiff). In some aspects, the system and components are designed such that their compliance is either constant and reproducible or negligible with respect to the vessel compliance that needs to be estimated. In some aspects, the pressure and / or compliance related signals are measured and shown over time to better visualize the various phases and events during the use of the device. In some aspects, the signals are labeled or annotated at known states to have a reference later in the procedure. For example, the moment that the balloon is inflated to a state that it starts expanding the vessel wall could be a good reference point for determining the baseline compliance of the vessel. In some aspects, the signal is normalized by a reference measurement that is recorded during a predetermined time point in the procedure. Using such a reference could help to detect events or changes more easily in the signal.

[0114] In some aspects, an algorithm is used to automatically detect events. An example could be detecting change in compliance by derivative analysis of the (smoothed) signal. In some aspects, a look-up table or machine learning / Al-based approach is used to recognize patterns in the signal and predict how to proceed. In some aspects, the feedback mechanism is designed such that in addition to detect calcium cracking, it also allows for detecting other clinically relevant events like vessel dissection and / or perforation. In some aspects, pressure variations due to beating of the heart are detected and / or monitored and used for signal gating such that it can be determined what pressure changes are due to heart movement. The pressure signal of interest can be corrected for the fluctuation due to heart movement. In some aspects, absolute and relative pressure variations due to beating of the heart are used to provide additional information about compliance of the vessel and / or other hemodynamic information, including heart rate. In some aspects, the speed of balloon inflation and maximum inflation pressures are tailored to the determined compliance. For example, in caseof a low-compliance balloon, the applied AP for inflation is low and maximum P for inflation is limited to prevent overinflation. Another example could be that higher AP and maximum P are allowed in case of a high-compliance balloon. In some aspects, there is a safety feature that halts balloon inflation in case of sudden drop in pressure and / or increase in volume. In some aspects, in case of a high-compliance balloon (e.g., relatively low pressure needed for large volume changes), a safety feature is enabled that prevents overinflation of the balloon.

[0115] Figure 12 is an example screen display 1200 for a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure. The screen display 1200 includes a balloon volume vs. time graph 1210 (e.g., in arbitrary units), a balloon pressure vs. time graph (e.g., in arbitrary units), and a balloon compliance vs. time graph (e.g., in arbitrary units). The screen display 1200 also includes annotations such as vertical lines 1240 and circle markers 1250 showing inflection points in the graphs 1210, 1220, 1230, as well as alphanumeric annotations 1260 that show, e.g., current values for volume, pressure, and balloon compliance. In some aspects, alphanumeric annotations 1260 can be an average value (e.g., a moving average), an absolute measure, a relative measure, etc. In general, the screen display 1200 can include a visual representation associated with the compliance (e.g., graph, alphanumeric output, etc.). In some aspects, the graphs 1210, 1220, and / or 1230 can be a time-history plot, which allows a user to monitor the change in volume, pressure, and / or compliance over time.

[0116] As shown in the graphs 1210, 1220, 1230, during a Phase 1 time period, the volume of the balloon increases significantly, while the pressure of the balloon increases only gradually, and the compliance changes very little or remains largely constant. Thus, as described above, the Phase 1 time period most likely represents expansion of the balloon while the balloon is not apposed.

[0117] During a Phase 2 time period, volume increases more slowly, while pressure increases dramatically, and compliance slowly decreases. Thus, as described above, the Phase 2 time period most likely represents expansion of the balloon while it is apposed by a calcified lesion or stenosis. The transition between Phase 1 and Phase 2 can be detected by the change in slope for the graphs 1210, 1220, and 1230, as well as a sudden drop 1270 in the compliance of the balloon.

[0118] During a Phase 3 time period, volume and pressure both increase slowly, while compliance slowly decreases. Thus, as described above, the Phase 3 time period most likely represents expansion of the balloon after the calcified lesion or stenosis has fractured, and the balloon is once again free to expand. The transition between Phase 2 and Phase 3 can bedetected by the change in slope for the graphs 1210, 1220, and 1230, and by a sudden increase 1280 in the volume of the balloon and a sudden drop 1290 in the pressure, leading to a sudden increase 1295 in compliance.

[0119] In some aspects, the screen display 1200 may be used directly by a clinician to determine that a change from Phase 1 to Phase 2 or from Phase 2 to Phase 3 has taken place. However, in other aspects, changes in volume, pressure, and compliance are analyzed automatically in order to control the angioplasty balloon automatically in real time. In an example, an clinician may activate a control marked “Fracture Mode” in order to initiate the inflation of the balloon through phases 1, 2, and 3, using automated methods shown below in Figures 13 and 14.

[0120] Figure 13 is a schematic, diagrammatic representation, in flow diagram form, of an example vessel dilation estimation method 1300, in accordance with at least one aspect of the present disclosure. It is understood that the steps of method 1300 may be performed in a different order than shown in Figure 13, additional steps can be provided before, during, and after the steps, and / or some of the steps described can be replaced or eliminated in other aspects. One or more of steps of the method 1300 can be carried by one or more devices and / or systems described herein, such as components of system 100, system 600, system 1900, system, 2100, processor circuit 112, console 110, and / or processor circuit 2350.

[0121] In step 1310, the method 1300 includes controlling a position sensor, flow sensor, volume sensor, or other sensor to obtain data associated with the volume of the angioplasty balloon during balloon inflation.

[0122] In step 1320, the method 1300 includes determining the volume of the balloon using the volume-associated data.

[0123] In step 1330, the method 1300 includes controlling a pressure sensor to obtain data representative of the pressure of the balloon during balloon inflation.

[0124] In step 1340, the method 1300 includes calculating the compliance of the balloon during balloon inflation, based on the determined volume and pressure.

[0125] In step 1350, the method 1300 includes outputting a graphical representation of the volume, pressure, and / or compliance of the balloon. Execution then returns to step 1310.

[0126] It is noted that flow diagrams and block diagrams are provided herein for exemplary purposes; a person of ordinary skill in the art will recognize myriad variations that nonetheless fall within the scope of the present disclosure. For example, the logic of flow diagrams may be shown as sequential. However, similar logic could be parallel, massively parallel, object oriented, real-time, event-driven, cellular automaton, or otherwise, whileaccomplishing the same or similar functions. In order to perform the methods described herein, a processor may divide each of the steps described herein into a plurality of machine instructions, and may execute these instructions at the rate of several hundred, several thousand, several million, or several billion per second, in a single processor or across a plurality of processors. Such rapid execution may be necessary in order to execute the method in real time or near-real time as described herein. For example, the vessel compliance estimation system may need, in real time, to determine the duration of the patient’s heartbeat, identify a particular point in the heartbeat cycle at which to capture temperature and pressure measurements, calculate the balloon compliance, and display the balloon compliance on a screen display. In some aspects, the vessel compliance estimation system may also perform real-time noise filtering of the volume, pressure, and / or compliance values. In some aspects, the vessel compliance estimation system may additionally control pumps, switches, transducers, and other components to control automatically and in real time, both the fracturing of the calcification and the determination that the fracturing is complete.

[0127] Figure 14 is a schematic, diagrammatic representation, in flow diagram form, of an example vessel dilation estimation method 1400, in accordance with at least one aspect of the present disclosure. It is understood that the steps of method 1400 may be performed in a different order than shown in Figure 14, additional steps can be provided before, during, and after the steps, and / or some of the steps described can be replaced or eliminated in other aspects. One or more of steps of the method 1400 can be carried by one or more devices and / or systems described herein, such as components of system 100, system 600, system 1900, system, 2100, processor circuit 112, console 110, and / or processor circuit 2350.

[0128] In step 1410, the method 1400 includes measuring the compliance of the balloon, as described above in Figure 13. Execution then proceeds to step 1420.

[0129] In step 1420, the method 1400 includes determining whether a sudden decrease (e.g., a decrease larger than a specified threshold value from the previous time step) in pressure has occurred. If yes, execution then proceeds to step 1425. If no, execution proceeds to step 1430.

[0130] In step 1425, the method 1400 includes determining that the balloon is apposed. This may mean, for example, that the balloon has expanded against a calcified stenosis such that further inflation becomes more difficult. Depending on the implementation, this determination may result in a message being displayed, or a cracking function (e.g., an ultrasound transducer) being activated. The method is now complete for this time step.

[0131] In step 1430, the method 1400 includes determining whether a gradual decrease (e.g., a decrease larger than a specified threshold value from the previous time step) has occurred. If Yes, execution then proceeds to step 1435. If no, execution proceeds to step 1440.

[0132] In step 1435, the method 1400 includes determining that the balloon is fully inflated. This may mean, for example, that further inflation of the balloon may increase the chance of rupturing the balloon or catheter. Depending on the implementation, this determination may result in a message being displayed, a fluid pump being switched off, etc. The method is now complete for this time step.

[0133] In step 1440, the method 1400 includes determining whether a sudden increase (e.g., an increase larger than a specified threshold value from the previous time step) in compliance has occurred. If Yes, execution then proceeds to step 1444. If no, execution proceeds to step 1460.

[0134] In step 1444, the method 1400 includes determining whether the compliance is effectively infinite, meaning for example that the pressure has dropped back to baseline value, and / or that pumping additional fluid into the balloon causes a zero or near-zero change in pressure. If Yes, execution then proceeds to step 1450. If no, execution proceeds to step 1446.

[0135] In step 1446, the method 1400 includes determining whether a sudden increase (e.g., an increase larger than a specified threshold value from the previous time step) has occurred. If Yes, execution then proceeds to step 1448. If no, execution proceeds to step 1470.

[0136] In step 1448, the method 1400 includes determining that calcium fracture has occurred. This may mean, for example, that further inflation of the balloon will successful dilate the vessel so that, for example, a stent can be placed. Depending on the implementation, this determination may result in a message being displayed, a fluid pump being switched on, etc. The method is now complete for this time step.

[0137] In step 1450, the method 1400 includes determining that a rupture has most likely occurred somewhere in the system (e.g., in the balloon, the catheter, the endoflator, etc.).Another possibility is that the vessel itself has dissected. Depending on the implementation, this determination may result in a message being displayed, pumps and actuators being switched off, etc. The method is now complete for this time step.

[0138] In step 1460, the method 1400 includes determining whether a gradual increase (e.g., an increase larger than a specified threshold value from the previous time step) incompliance has occurred. If Yes, execution then proceeds to step 1465. If no, execution proceeds to step 1480.

[0139] In step 1465, the method 1400 includes determining whether the volume is increasing vs. the previous time step. If Yes, execution then proceeds to step 1470. If no, execution proceeds to step 1490.

[0140] In step 1470, the method 1400 includes determining that vessel dilation is in progress. The method is now complete for this time step.

[0141] In step 1480, the method 1400 includes determining that the balloon is in a normal, unapposed condition of inflation, deflation, or stasis. Depending on the implementation, this determination may result in a message being displayed. The method is now complete for this time step.

[0142] In step 1490, the method 1400 includes determining that there is probably a leak somewhere in the system (e.g., in the balloon, the catheter, the endoflator, etc.) or a perforation in the vessel. Depending on the implementation, this determination may result in a message being displayed, or the switching off of pumps, actuators, etc. The method is now complete for this time step.

[0143] It is noted that the tests and sequences of this method may be different than shown in Figure 14, without departing from the spirit of the present disclosure.

[0144] Figure 15 is a schematic, diagrammatic representation of an example balloon angioplasty system 1500 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. The balloon angioplasty system 600 includes a console or workstation 110, an electromechanical endoflator 120, and a balloon catheter 130, which includes a catheter body or flexible elongate member 135 in fluid communication with a balloon 140.

[0145] In an example, the console 110 includes a housing 118 that encloses a processor circuit 112 in communication with an electrical power source (e.g., a current source and / or voltage source) 114 and a display 116. In an example, the electromechanical endoflator 120 includes a housing 190 and a manual actuator 160 that permits a clinician to increase the static pressure of a fluid chamber 180 that is in fluid communication with the balloon catheter 130 via a fluid line 195.

[0146] The electromechanical endoflator 120 also includes an electromechanical actuator 170 which receives power from the electrical power source 114 via a cable 150. Similar to the manual actuator 160, the electromechanical actuator 170 can provide a transient pressure, additive to the static pressure of the fluid chamber 180 and thus communicated to the ballooncatheter 130 via the fluid line 195. The electromechanical actuator may for example be an ultrasound transducer. In the example shown in Figure 15, the electromechanical endoflator 120 also includes an ultrasonic sensor 1510 that can be used to measure a time-varying pressure within the electromechanical endoflator, which is related to a time-varying pressure within the balloon 140. It is noted that in some cases, a single ultrasound transducer may be configured to operate as both an electromechanical actuator 170 and an ultrasonic sensor 1510, although in other cases it may be advantageous for these functions to be performed by two separate components.

[0147] This aspect is like aspect 1 with the main difference that in addition to the static pressure in the balloon-catheter system, a dynamic pressure component is used to derive information about (changes) in vessel compliance. An ultrasonic actuator is used to generate pressure waves. Preferably, but not necessarily, the ultrasonic actuator is in the external endoflator to keep the balloon-device and catheter small. The fluid in the balloon and through fluid channel(s) within the catheter serve as medium for propagation of the pressure waves in any either direction. A part of the signal that reaches the balloon and surrounding tissue and / or blood will be reflected. This response signal is measured by an ultrasonic sensor and processed subsequently.

[0148] In some aspects, the pressure signal serves a dual purpose: it is used to generate the desired shockwave effect to modify the calcium, and it causes a dynamic tissue response signal representative of the treatment progress. In some aspects, the various system components, especially the catheter and / or fluid channel(s) to guide the pressure waves in either direction, are designed such that the pressure signals in either direction are dampened minimally by the system. This can be done for example by making the tubes etc very stiff. In some aspects, the various system components are designed such that the resonance frequency does not overlap with the frequency being used for dynamic measurements. In some aspects, the ultrasonic actuator and sensor are a single component that can be used in different modes (i.e. actuation and sensing).

[0149] Figure 16A is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, catheter body 135 (with catheter lumen 330), balloon 140, and fluid 310. The catheter body 135 and balloon 140 have been positioned within a blood vessel 410 that includes a calcified stenosis 430.

[0150] In the example shown in Figure 16A, the electromechanical actuator 170 also serves as an ultrasonic sensor 1510. Thus, as the vibrations of the electromechanical actuator 170 drives fluid 310 into and out of the balloon 140 to generate hydraulic shockwaves, the electromechanical actuator 170 also takes high-frequency pressure and flow measurements that are indicative of the pressure within the balloon and the volume of the balloon at various points in the ultrasonic vibration cycle. These pressure and volume values can then be used to compute the compliance of the balloon.

[0151] Figure 16B is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, catheter body 135 (with catheter lumen 330), balloon 140, and fluid 310. The catheter body 135 and balloon 140 have been positioned within a blood vessel 410 that includes a calcified stenosis 430.

[0152] Figure 16B is similar to Figure 16A, except that the electromechanical actuator 170 and ultrasonic sensor 1510 are two separate components. In the example shown in Figure 16B, the ultrasonic sensor 1510 is positioned at the distal entrance of the catheter lumen 330, although it can in principle be placed anywhere in the system that is in contact with the pressurized fluid 310.

[0153] Figure 16C is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. Visible are the electromechanical endoflator 120, manual actuator 160, fluid chamber 180, transient pressure chamber 210, piezoelectric electromechanical actuator 170, catheter body 135 (with catheter lumen 330), balloon 140, and fluid 310. The catheter body 135 and balloon 140 have been positioned within a blood vessel 410 that includes a calcified stenosis 430.

[0154] Figure 16C is similar to Figure 16B, except that the ultrasonic sensor 1510 has been positioned in a separate pressure sensing lumen 1630 within the catheter body 135 that s in fluid communication with the balloon 140 but is separated from the electromechanical actuator 170 by the transient pressure chamber 210, catheter lumen 330 and pressure sensing lumen 1630, thus providing some buffering from the vibrations of the electromechanical actuator 170 and thus a more accurate measurement of the pressure within the balloon 140 as the fluid 310 periodically vibrates in and out of the balloon 140. In some aspects, the separation of the pressure sensing lumen 1630 from the catheter lumen 330 allows the twolumens to guide the transversal pressure waves in either direction between the endoflator and balloon, thereby facilitating continuous measurements rather than pulsed.

[0155] Figure 17 is a schematic, diagrammatic representation, in flow diagram form, of an example vessel dilation estimation method 1700, in accordance with at least one aspect of the present disclosure. It is understood that the steps of method 1700 may be performed in a different order than shown in Figure 17, additional steps can be provided before, during, and after the steps, and / or some of the steps described can be replaced or eliminated in other aspects. One or more of steps of the method 1700 can be carried by one or more devices and / or systems described herein, such as components of system 100, system 600, system 1900, system, 2100, processor circuit 112, console 110, and / or processor circuit 2350.

[0156] In step 1710, the method 1700 includes controlling an ultrasonic oscillator (e.g., the electromechanical actuator 170) to operate at a first frequency. Execution then proceeds to step 1720.

[0157] In step 1720, the method 1700 includes determining the balloon compliance associated with first frequency. As described above, balloon compliance can be calculated or estimated as a function of the balloon volume and pressure. Execution then proceeds to step 1730.

[0158] In step 1730, the method 1700 includes controlling the ultrasonic oscillator to operate at a second frequency. Execution then proceeds to step 1740.

[0159] In step 1740, the method 1700 includes determining the balloon compliance associated with second frequency. Execution then proceeds to step 1750.

[0160] In step 1750, the method 1700 includes using the compliance measurements of steps 1720 and 1740 to generate a curve of frequency vs. compliance for the particular balloon currently in use. Execution then proceeds to step 1760.

[0161] In step 1760, the method 1700 includes performing a characterization of the lesion based on the curve. For example, if the expanding balloon suddenly exhibits a compliance that is much lower than the curve indicates it should be at the current ultrasound frequency, then the balloon is most likely apposed by the lesion, and the lesion is most likely calcified. If the apposed balloon suddenly exhibits a compliance more in line with what the curve indicated it should be, then the calcification has most likely been fractured. Execution then proceeds to at least one of step 1770 or 1780.

[0162] In step 1770, the method 1700 includes controlling delivery of therapy to the lesion based on the characterization. For example, if the characterization indicates that the balloon is apposed but the calcification has not yet fractured, then further inflation and / orvibration of the balloon may be performed, whereas if the characterization indicates that the calcification has cracked, then the vibration / hydraulic shocking may be terminated. The method may now be complete, or may return to step 1760.

[0163] In step 1780, the method 1700 includes outputting graphical representation based on curve and / or characterization. The method may now be complete, or may return to step 1760.

[0164] Although only two data points are captured in this example, a person of ordinary skill in the art will appreciate that many data points could be captured in the same or a similar manner, to perform an automated characterization of both the balloon and the stenosis.

[0165] Figure 18 is a frequency vs. compliance curve 1800, in accordance with at least one aspect of the present disclosure. The frequency vs. compliance curve 1800 may for example be a balloon calibration curve that measures compliance 1810 (e.g., in arbitrary units) of the balloon on the Y-axis and frequency 1820 (e.g., in Hertz) on the X-axis. The compliance values may for example be calculated based on dynamic pressure values as shown for example in Figures 5A and 5B. The curve 1830 shows a characteristic shape that includes high points 1840 and 1850, and a dip 1860, that characterize the balloon being used in the current procedure. Any deviation from this curve may therefore be indicative of changes in the stenosis, such as balloon apposition or a fracturing of the stenosis. Preferably, an algorithm is used in combination with a look-up table or database to provide lesion characterization. Understanding lesion morphology can be pivotal in choosing the proper vessel preparation tool. In an example, a database and Al can be used to perform lesion quantification and prediction on what vessel prep devices to use to achieve optimal outcome.

[0166] Figure 19 is a schematic, diagrammatic representation of an example balloon angioplasty system 1900 with manual endoflator 1910, in accordance with at least one aspect of the present disclosure. The balloon angioplasty system 1900 includes a console or workstation 110, a manual endoflator 1910, and a balloon catheter 130, which includes a catheter body or flexible elongate member 135 in fluid communication with a balloon 140.

[0167] In an example, the console 110 includes a housing 118 that encloses a processor circuit 112 in communication with an electrical power source (e.g., a current source and / or voltage source) 114 and a display 116. In an example, the manual endoflator 1910 includes a housing 190 and a manual actuator 160 that permits a clinician to increase the static pressure of a fluid chamber 180 that is in fluid communication with the balloon catheter 130 via a fluid line 195.

[0168] In the example shown in Figure 19, the electromechanical endoflator 120 also includes a pressure sensor 610 and flow sensor 620, whose functions are described above. In previously discussed aspects, the feedback mechanism was positioned it an add-on to an ultrasonic endoflator. However, the same technology can be applied to simpler devices like a manually inflated, non-compliant balloon. In this case, the sensors are used for lesion characterization, rather than using the sensor as monitoring / feedback add-on to an ultrasonic endoflator device or another device for lithotripsy. Non-compliant balloons are typically used as a first-line option before physicians escalate to more advanced, more expensive, and sometimes riskier devices and tools. One issue is that the decision tree on what tools to use is mainly based on simplicity, safety profile and costs, and less on the specific characteristics of a calcification. This means a trial-and-error approach and limited occurrence of selecting the right tool on the first try. Having a sensor that characterizes the lesion during inflation of the balloon is therefore an improvement in the art. This can be done either by determining the changes in vessel compliance during simple volume-pressure measurements, or by adding a dynamic pressure generator-sensor combination to do more advanced characterization. All previously described aspects can be applied to simpler balloon-based devices without the ultrasonic endoflator working mechanism.

[0169] Figure 20 is a schematic, diagrammatic view of at least a portion of an example balloon angioplasty system 100 with manual endoflator 1910, in accordance with at least one aspect of the present disclosure. Visible are the manual endoflator 1910, manual actuator 160, fluid chamber 180, catheter 130 including catheter body 135 (with catheter lumen 330) and balloon 140, fluid 310, pressure sensor 610, and flow sensor 620. As the manual endoflator inflates the balloon, the balloon generates increasing hydraulic force which can eventually crack, fracture, or fragment the calcified stenosis.

[0170] Figure 21 is a schematic, diagrammatic representation of an example balloon angioplasty system 2100 with electromechanical endoflator 120, in accordance with at least one aspect of the present disclosure. The balloon angioplasty system 2100 includes a console or workstation 110, an electromechanical endoflator 120, and a balloon catheter 130, which includes a catheter body or flexible elongate member 135 in fluid communication with a balloon 140.

[0171] In an example, the console 110 includes a housing 118 that encloses a processor circuit 112 in communication with an electrical power source (e.g., a current source and / or voltage source) 114 and a display 116. In an example, the electromechanical endoflator 120 includes a housing 190 and a manual actuator 160 that permits a clinician to increase thestatic pressure of a fluid chamber 180 that is in fluid communication with the balloon catheter 130 via a fluid line 195. The electromechanical endoflator 120 also includes an electromechanical actuator 170 which receives power from the electrical power source 114 via a cable 150.

[0172] In the example shown in Figure 21, the balloon 140 includes electrodes that can be used to measure electrical properties (e.g., impedance) of the tissue in contact with the balloon 140, to enable impedance spectroscopy. When measuring the impedance as a function of the frequency between the various electrodes, changes in the impedance can be determined. The impedance is measured between the various electrode combination such that the probing area covers a significant portion of the vessel wall. These changes in impedance during treatment are for instance caused when solid calcium parts are cracked into smaller pieces, such that conductive intracellular fluid can enter in between the cracked calcium parts, thus altering the conductivity and permittivity of the tissue proximate to the balloon. When continuously measuring the impedance as function of the frequency, these changes can be measured and used to monitor the treatment progression.

[0173] Examples of how to integrate the electrodes onto the balloon are shown below.

[0174] Figure 22A is a schematic, diagrammatic representation of at least a portion of an example balloon angioplasty system 2100 which incorporates a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure. Visible are the processor circuit 112, electrical power source 114, and balloon 140. In the example shown in Figure 22A, one electrode 2110 is located on the balloon, and a counter electrode 2210 on the body of the patient 2220, which allows the impedance to be measured between these electrodes. The electrodes 2110 can be made from flexible polyimide and attached to the balloon surface via silicon adhesive 2230. As a result, the size of the balloon is not affected by the presence of the electrodes and the same diameter catheter can be used.

[0175] Figure 22B is a schematic, diagrammatic representation of at least a portion of an example balloon angioplasty system 2100 which incorporates a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure. Visible are the processor circuit 112, electrical power source 114, and balloon 140. In the example shown in Figure 22B, there are at least two electrodes 2210 located on the balloon 140, allowing impedance measurement between these electrodes. One advantage of this configuration is that the impedance is measure locally near the balloon 140, leading to a higher sensitivity for impedance changes related to the change in permittivity and conductivity in the vessel wall.

[0176] The electrodes may for example be integrated onto the balloon surface such that they are in contact with the vessel wall when the balloon is inflated. Impedance spectroscopy is preferably be performed between 10 Hz and 1MHz, although it can also be performed at higher or lower frequencies, including direct current (DC) at 0 Hz.

[0177] Figure 22C is a schematic, diagrammatic representation of at least a portion of an example balloon angioplasty system 2100 which incorporates a vessel compliance estimation system, in accordance with at least one aspect of the present disclosure. Visible are the processor circuit 112, electrical power source 114, and balloon 140. In the example shown in Figure 22C, the balloon 140 is a scoring balloon that includes blades 2240, and the electrodes 2110 are incorporated directly into the blades.

[0178] It is noted with particular emphasis that the impedance sensing features of Figures 21-22C can be combined with any or all of the pressure and / or flow measurements described above. Furthermore, each modality improves the likelihood of accurately detecting and quantifying or characterizing the cracking of calcified lesions. If two or more methods can be compared and are in agreement, then a high confidence of the cracking can be shown to the physician. When two or more methods indicate no cracking or minimal cracking has occurred, then the system can report with a high confidence that the calcium is not cracked. When two or more methods are not in agreement, then both results can be displayed, but showing a lower confidence.

[0179] Figure 23 is a schematic diagram of a processor circuit 2350, according to at least one aspect of the present disclosure. The processor circuit 2350 may be implemented in system 100, system 600, system 1900, system, 2100, processor circuit 112, console 110, or other devices or workstations (e.g., third-party workstations, network routers, etc.), or on a cloud processor or other remote processing unit, as necessary to implement the method. As shown, the processor circuit 2350 may include a processor 2360, a memory 2364, and a communication module 2368. These elements may be in direct or indirect communication with each other, for example via one or more buses.

[0180] The processor 2360 may include a central processing unit (CPU), a digital signal processor (DSP), an ASIC, a controller, or any combination of general-purpose computing devices, reduced instruction set computing (RISC) devices, application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other related logic devices, including mechanical and quantum computers. The processor 2360 may also comprise another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 2360 may also be implemented as acombination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0181] The memory 2364 may include a cache memory (e.g., a cache memory of the processor 2360), random access memory (RAM), magnetoresistive RAM (MRAM), readonly memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an aspect, the memory 2364 includes a non-transitory computer-readable medium. The memory 2364 may store instructions 2366. The instructions 2366 may include instructions that, when executed by the processor 2360, cause the processor 2360 to perform the operations described herein. Instructions 2366 may also be referred to as code. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may include a single computer-readable statement or many computer-readable statements.

[0182] The communication module 2368 can include any electronic circuitry and / or logic circuitry to facilitate direct or indirect communication of data between the processor circuit 2350, and other processors or devices. In that regard, the communication module 2368 can be an input / output (VO) device. In some instances, the communication module 2368 facilitates direct or indirect communication between various elements of the processor circuit 2350 and / or system 100, system 600, system 1900, system, 2100, processor circuit 112, or console 110. The communication module 2368 may communicate within the processor circuit 2350 through numerous methods or protocols. Serial communication protocols may include but are not limited to United States Serial Protocol Interface (US SPI), Inter- Integrated Circuit (I2C), Recommended Standard 232 (RS-232), RS-485, Controller Area Network (CAN), Ethernet, Aeronautical Radio, Incorporated 429 (ARINC 429), MODBUS, Military Standard 1553 (MIL-STD-1553), or any other suitable method or protocol. Parallel protocols include but are not limited to Industry Standard Architecture (ISA), Advanced Technology Attachment (ATA), Small Computer System Interface (SCSI), Peripheral Component Interconnect (PCI), Institute of Electrical and Electronics Engineers 488 (IEEE- 488), IEEE-1284, and other suitable protocols. Where appropriate, serial and parallel communications may be bridged by a Universal Asynchronous Receiver Transmitter(UART), Universal Synchronous Receiver Transmitter (US ART), or other appropriate subsystem.

[0183] External communication (including but not limited to software updates, firmware updates, preset sharing between the processor and central server, or readings from the pressure gauge) may be accomplished using any suitable wireless or wired communication technology, such as a cable interface such as a universal serial bus (USB), micro USB, Lightning, or FireWire interface, Bluetooth, Wi-Fi, ZigBee, Li-Fi, or cellular data connections such as 2G / GSM (global system for mobiles) , 3G / UMTS (universal mobile telecommunications system), 4G, long term evolution (LTE), WiMax, or 5G. For example, a Bluetooth Low Energy (BLE) radio can be used to establish connectivity with a cloud service, for transmission of data, and for receipt of software patches. The controller may be configured to communicate with a remote server, or a local device such as a laptop, tablet, or handheld device, or may include a display capable of showing status variables and other information. Information may also be transferred on physical media such as a USB flash drive or memory stick.

[0184] As will be readily appreciated by those having ordinary skill in the art after becoming familiar with the teachings herein, the vessel compliance estimation system advantageously provides a capability to detect and characterize the fracturing of calcified vascular stenoses (including those in peripheral and coronary veins and arteries), using either custom catheters or off-the-shelf non-compliant catheters, and using custom angioplasty balloons or off-the-shelf balloons, including compliant balloons, non-compliant balloons, cutting balloons, and otherwise. Such detection and characterization permits a clinician to determine when a calcified stenosis has been sufficiently fractured to enable vessel dilation with the balloon, and (if needed) the placement and expansion of a stent.

[0185] The technology disclosed herein can be used for treatment of coronary artery disease, in particular for complex percutaneous coronary interventions (PCI). The technology can be detected by the features that are present in the device. For instance, the presence of a means to measure the pressure and flow, or electrodes that are present for measuring the impedance, indicate that a vessel compliance estimation system is in use. Furthermore, the output presented to the physician regarding the treatment progression can also easily be detected.

[0186] A number of variations are possible on the examples and aspects described above.For example, other types of electromechanical actuators, or other physical arrangements of mechanical and electromechanical actuators, could be employed than those described herein,without departing from the spirit of the present disclosure. The vessel compliance estimation system could be used in other body lumens where there is clinical benefit in a hydraulic shock or vibration delivered through a balloon catheter. Different types of sensors, actuators, or pressure vs. time profiles may be used instead of or in addition to those described herein.

[0187] Accordingly, the logical operations making up the aspects of the technology described herein are referred to variously as operations, steps, objects, elements, components, or modules. Furthermore, it should be understood that these may occur, or be performed or arranged, in any order, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.

[0188] All directional references e.g., upper, lower, inner, outer, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, proximal, and distal are only used for identification purposes to aid the reader’s understanding of the claimed subject matter, and do not create limitations, particularly as to the position, orientation, or use of the vessel compliance estimation system. Connection references, e.g., attached, coupled, connected, joined, or “in communication with” are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily imply that two elements are directly connected and in fixed relation to each other. The term “or” shall be interpreted to mean “and / or” rather than “exclusive or.” The word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. Unless otherwise noted in the claims, stated values shall be interpreted as illustrative only and shall not be taken to be limiting.

[0189] The above specification, examples and data provide a complete description of the structure and use of exemplary aspects of the vessel compliance estimation system as defined in the claims. Although various aspects of the claimed subject matter have been described above with a certain degree of particularity, or with reference to one or more individual aspects, those skilled in the art could make numerous alterations to the disclosed aspects without departing from the spirit or scope of the claimed subject matter. Still other aspects are contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular aspects and not limiting. Changes in detail or structure may be made without departing from the basic elements of the subject matter as defined in the following claims.

Claims

CLAIMSWhat is claimed is:

1. An apparatus, comprising: an endoflator configured for fluid communication with an intravascular catheter, wherein the endoflator is configured to inflate a balloon of the intravascular catheter with a fluid; and a processor, wherein at least one of the intravascular catheter or the endoflator comprises a first sensor configured to provide a first output, wherein the processor is configured to: compute a compliance of the balloon based on the first output of the first sensor; and provide, to a display in communication with the processor, a visual representation associated with the compliance.

2. The apparatus of claim 1, further comprising the intravascular catheter.

3. The apparatus of claim 1, wherein at least one of the intravascular catheter or the endoflator comprises a second sensor configured to provide a second output, wherein the processor is configured to compute the compliance based on the second output of the second sensor.

4. The apparatus of claim 3, wherein the first output is indicative of a pressure inside the balloon, wherein the second output is indicative of a volume of the fluid inside the balloon.

5. A device for measuring compliance of a balloon of a balloon catheter, the device comprising: a processor; a first sensor configured for communication with the processor; and a second sensor configured for communication with the processor,wherein the processor is configured to compute, based on an output of the first sensor and an output of the second sensor, a compliance of a balloon of a balloon catheter positioned proximate to the calcified stenosis of a blood vessel, wherein the compliance is indicative of a degree of fracturing of the calcified stenosis by the balloon.

6. The device of claim 5, further comprising a display, wherein the processor is configured to display, on the display, a time-history plot or alphanumeric output indicative of the compliance of the balloon.

7. The device of claim 5, wherein: the first sensor is a first electrode; the second sensor is a second electrode, and the processor is configured to compute the compliance of the balloon based on an impedance of tissue in contact with the first electrode and the second electrode.

8. The device of claim 5, wherein: the first sensor is a pressure sensor in fluid communication with the balloon and in electronic communication with the processor, such that a pressure measurement from the pressure sensor is indicative of a pressure inside the balloon, the second sensor is a position sensor, flow sensor, or volume sensor in fluid communication with the balloon and in electronic communication with the processor, such that a position, flow, or volume measurement from the position sensor, flow sensor, or volume sensor is indicative of a volume of fluid inside the balloon, and the processor is configured to compute the compliance of the balloon based on the pressure inside the balloon and the volume of fluid inside the balloon.

9. The device of claim 8, wherein, when the balloon is positioned within a calcified stenosis of a blood vessel of a patient, the computed compliance is indicative of a degree of fracturing of the calcified stenosis.

10. The device of claim 9, further comprising an electromechanical endoflator configured to cyclically inflate and deflate the balloon with an electromechanical actuator to generate hydraulic shockwaves configured to fracture the calcified stenosis.

11. The device of claim 10, wherein the electromechanical actuator comprises the pressure sensor.

12. The device of claim 10, wherein the electromechanical actuator comprises the position sensor, flow sensor, or volume sensor.

13. The device of claim 10, wherein the pressure measurement is a dynamic pressure measurement.

14. The device of claim 9, further comprising a manual endoflator configured to inflate the balloon to generate hydraulic force configured to fracture the calcified stenosis.

15. A system for measuring compliance, comprising: a processor; a balloon catheter comprising a balloon; an endoflator configured for fluid communication with the balloon catheter, wherein the endoflator is configured to provide fluid to the balloon to inflate the balloon, wherein the balloon catheter or the endoflator comprises: a pressure sensor in fluid communication with the balloon and in electronic communication with the processor, such that a pressure measurement from the pressure sensor is indicative of a pressure inside the balloon; and a position sensor, flow sensor, or volume sensor in fluid communication with the balloon and in electronic communication with the processor, such that a position, flow, or volume measurement from the position sensor, flow sensor, or volume sensor is indicative of a volume of fluid inside the balloon, wherein the processor is configured to compute the compliance of the balloon based on the pressure inside the balloon and the volume of fluid inside the balloon; and a display, wherein the processor is configured to display, on the display, a graph or alphanumeric output indicative of the compliance of the balloon,wherein, when the balloon is positioned within a calcified stenosis of a blood vessel of a patient, the computed compliance is indicative of a degree of fracturing of the calcified stenosis.

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