Drive unit for intravascular circulatory support systems

Abstract

To provide a drive unit for an intravascular circulatory support system (e.g., a system including an IABP) that is fast enough.SOLUTION: A drive unit for intravascular circulatory support systems includes a motor, a ball nut, a ball screw, and a bellows. The motor includes a rotor and a stator. The ball nut is affixed to the rotor. The bellows has a first end, a second end, and a bellows cavity located therebetween. The first end is in a fixed position, and the second end is defined by a dynamic flange having a recess carried by the bellows cavity. The recess of the dynamic flange carries at least a portion of the motor. The second end also receives the ball screw. Rotation of the rotor causes linear motion of the ball screw within the ball nut to actuate the bellows.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present technology relates to systems, devices, and methods for treating heart failure, and more particularly to drive units for intravascular circulatory support systems. [Background technology]

[0002] background The prevalence of heart failure is increasing worldwide, resulting in a costly burden for healthcare providers. Despite medical advances, the prognosis for patients with heart failure remains poor, especially for those with advanced heart failure. This is partly due to limited treatment options for these patients. Counterpulsation using an intravascular circulatory support system is one treatment option for heart failure. Such a system may include a thin, flexible tube called a catheter with a long, thin balloon attached to the catheter's tip. The balloon is positioned within the patient's aorta. The other end of the catheter may be attached to a computer console or "drive unit" with a mechanism for inflating and deflating the balloon at appropriate times during the heartbeat. Actuation of the balloon acts as a balloon pump (i.e., an intra-aortic balloon pump (IABP)). The drive unit may inflate the balloon when the heart relaxes to push blood toward the end organs and the coronary arteries that perfuse the heart. The drive unit may then deflate the balloon before the left ventricle contracts, reducing the pressure against which the heart must pump. This allows the heart to pump more blood through the body using less energy. The drive unit may continuously inflate and de-inflate the balloon in sync with the heartbeat.

[0003] Conventional drive units may utilize helium to inflate and de-inflate the balloon. However, there are technical costs, patient usability and portability issues, and safety risks associated with the use of helium. For example, the drive unit must contain (or be connected to) a storage tank containing helium. As a result, conventional drive units are too large and heavy to be portable. A typical drive unit using helium weighs 50-100 lbs, limiting its use to hospitals. Furthermore, if the balloon leaks or ruptures, the helium is not rapidly absorbed into the blood, posing a significant risk to the patient for blood clot formation and stroke.

[0004] Furthermore, balloon inflation and de-inflation out of sync with the patient's heartbeat can be significantly harmful or at least therapeutically counterproductive. For example, early balloon inflation can increase left ventricular afterload (i.e., the amount of resistance the heart must overcome to open the aorta and pump blood volume into the systemic circulation). If the balloon is inflated too early, the left ventricle may still be in the process of contracting and attempting to eject blood through the open aortic valve. Thus, the left ventricle may not only work against systemic vascular resistance, but also against the additional resistance of the inflated balloon in the aorta, which impedes blood flow from the heart. Some blood may also be forced back into the left ventricle through the aorta, increasing ventricular volume and placing greater stress on its wall. Slower balloon inflation can result in reduced diastolic blood pressure elevation. To be therapeutically effective, the drive unit may inflate the balloon immediately after the aortic valve closes. If inflation occurs long after aortic valve closure, the balloon will not have enough time to pump blood to the body and heart during diastole, reducing therapeutic effectiveness. Early balloon de-inflation will not effectively reduce ventricular workload and myocardial oxygen demand. If the balloon is de-inflated too early, the aortic pressure may have time to equilibrate, proximal diastolic pressure may return to unassisted levels, and there may be no reduction in the duration of isovolumic contraction of the left ventricle or the afterload against which the heart must eject. Early balloon de-inflation may result in a failure to reduce myocardial oxygen demand. While early balloon de-inflation may provide some benefit in increasing diastolic pressure, the left ventricle may not be assisted in opening the aortic valve, resulting in less reduction in afterload. Late balloon de-inflation may increase afterload because there is insufficient time for the aortic end-diastolic pressure to decrease before the left ventricle is ready to contract again.

[0005] The drive unit may inflate and de-inflate the balloon at the correct time based, at least in part, on real-time sensing and analysis of the patient's electrocardiogram (ECG or EKG). However, even if signals are perfectly sensed and delivered to the drive unit, mechanical inefficiencies in the drive unit can cause some delay in the actual inflation-de-inflation cycle of the balloon. This delay can hinder the therapeutic application of counterpulsation using an IABP for some cardiovascular conditions. Arrhythmias, such as atrial fibrillation, are particularly sensitive to such delays due to the irregular and often rapid heart rate that occurs when the two upper chambers of the heart receive disorganized electrical signals. For example, in patients with a-fib or other arrhythmias, to prevent an inflated balloon from interfering with the operation, the balloon should de-inflate by at least 50% within approximately 100 milliseconds of receiving the R wave in the QRS complex. Therefore, a need exists for a drive unit for an intravascular circulatory support system (e.g., a system including an IABP) that is fast enough to provide safe and effective therapy for patients with arrhythmias, irregular heartbeats, or a-fib. Another need exists for a drive unit that does not require expensive, large, heavy, and therefore largely non-portable helium tanks. Similarly, a need exists for a drive unit that uses fluids other than helium to avoid or mitigate the risks posed by using helium to inflate the balloon. Finally, a need exists for a drive unit that is more portable, with reduced weight and size compared to conventional drive units. Summary of the Invention

[0006] [Brief explanation of the drawings]

[0007] Many aspects of the present technology can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure.

[0008] [Figure 1]1 illustrates an example of an intravascular circulatory support system implanted within a patient's vasculature. [Figure 2A] 1 illustrates a top perspective exterior view of a first exemplary embodiment of a drive unit for an intravascular circulatory support system. [Figure 2B] 2B illustrates a top external view of the drive unit of FIG. 2A. [Figure 2C] 2B illustrates a side external view of the drive unit of FIG. 2A. [Figure 2D] 2B illustrates an end view of the drive unit of FIG. 2A. [Figure 2E] 2A and 2D illustrate cross-sectional views of the drive unit of FIG. 2A along section AA. [Figure 2F] 2A and 2D illustrate an exploded view of a portion of the drive unit of FIG. 2A along section AA. [Figure 3A] 1 illustrates a top external perspective view of a second exemplary embodiment of a drive unit of an intravascular circulatory support system. [Figure 3B] 3B illustrates an external end view of the drive unit of FIG. 3A. [Figure 3C] 3B illustrates a first side external view of the drive unit of FIG. 3A. [Figure 3D] 3B illustrates a second side external view of the drive unit of FIG. 3A. [Figure 3E] 3C and 3D illustrate cross-sectional views of the drive unit of FIG. 3A along section CC. [Figure 4] FIG. 3B illustrates a block diagram of certain control components applicable to the drive units of FIGS. 2A and 3A. DETAILED DESCRIPTION OF THE INVENTION

[0009] Detailed Description Specific details of several embodiments of the present technology are described below with reference to the drawings. Many of the embodiments of the present invention are described below with reference to the use of an intravascular circulatory support system / intravascular ventricular assist device ("iVAD"), which positions an IABP / balloon within the aorta to provide counterpulsation to help circulate blood throughout the body; however, other applications and embodiments in addition to those described herein are within the scope of the present technology. For example, some other embodiments of the present technology may have different configurations, components, or procedures than those described herein, and features of the embodiments shown herein may be combined with one another. Thus, those skilled in the art will understand that the present technology may have other embodiments with additional elements or that the present technology may have other embodiments without some of the features depicted and described below.

[0010] The terms used in the description provided below are intended to be interpreted in their broadest reasonable manner, even when used in connection with the detailed description of certain specific embodiments of the present technology. Certain terms may be emphasized below. However, terms intended to be interpreted in a limited manner are clearly and specifically defined as such in this detailed description section. In addition, the present technology may include other embodiments that fall within the scope of the embodiments but are not described in detail with respect to the drawings.

[0011] Throughout this specification, a reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described with respect to that embodiment is included in at least one embodiment of the present technology. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, particular features or characteristics may be combined in any suitable manner in one or more embodiments.

[0012] Heart failure and the circulatory support system Heart failure occurs when the heart cannot maintain blood flow to meet the body's needs. This occurs when the heart cannot pump adequately during contraction or cannot fill adequately during relaxation. Heart failure is a widespread, costly, and potentially fatal condition. For example, heart failure currently affects approximately 6.5 million people in the United States and is expected to increase by 46% by 2030. The stage / severity of heart failure can be defined using the New York Heart Association (NYHA) class, with NYHA Class I representing early disease and NYHA Class IV representing later disease. Current treatment options for heart failure vary depending on the stage of heart failure and include, among other options, drug therapy, cardiac resynchronization therapy (CRT), long-term mechanical circulatory support (e.g., left ventricular assist devices or "LVADs"), and heart transplantation. Drug therapy and CRT are typically used in relatively early cases (e.g., patients with NYHA Class II or early NYHA Class III heart failure). However, these treatments typically only slow the progression of heart failure, meaning that patients who initially respond to medical therapy or CRT typically experience disease progression and require more advanced therapeutic intervention.

[0013] The prognosis for patients with heart failure remains poor: 1-year mortality rates are approximately 15.0% for patients with NYHA Class III and approximately 28.0% for patients with NYHA Class IV. This is at least in part due to the limited number of treatment options available for patients with late NYHA Class III / early NYHA Class IV heart failure. For example, heart transplantation offers the best chance for long-term survival for patients with late NYHA Class IV, but this option is limited by a shortage of donor organs (e.g., approximately 2,000 transplants per year in the United States, 200 transplants per year in Canada, and less than 100 transplants per year in Japan). Therefore, many patients with NYHA Class III and IV must rely on other treatments. For example, some patients receive LVAD therapy as a bridge to heart transplantation or as a stand-alone treatment. However, LVAD therapy has several inherent drawbacks that limit its widespread use. Current LVAD therapy is expensive (e.g., over $100,000), typically requires a major surgical procedure for implantation (typically a sternotomy or thoracotomy), typically requires the use of cardiopulmonary bypass during the implantation procedure, and typically requires blood products (e.g., approximately 11.6 units of blood products). LVAD therapy, implanted through less invasive means (e.g., percutaneously), is used only for short-term circulatory support. Furthermore, postoperative care for patients receiving LVADs can be difficult and costly, and patient anxiety can be significant because device power interruptions or loss must not last longer than a few minutes. LVAD therapy is also associated with several serious adverse events, including device failure, thrombosis, thromboembolism, stroke, infection, and bleeding. For at least these reasons, LVAD therapy is typically reserved for patients with end-stage heart failure (e.g., late NYHA Class IV) who have limited options. This leaves a significant proportion of patients with heart failure too advanced for CRT but not severe enough to justify LVAD therapy / heart transplant (e.g., late NYHA Class III / early NYHA Class IV patients) without effective treatment options.Currently, there are approximately 1.6 million patients in the United States and 3.9 million in Europe with late Class III / early Class IV heart failure, representing a large patient population with limited treatment options.

[0014] Another treatment option for heart failure is counterpulsation therapy using an intra-aortic balloon pump (IABP). Counterpulsation therapy is achieved by rapidly inflating a balloon positioned within the patient's aorta immediately after aortic valve closure (dicrotic notch) and then rapidly deflating the balloon just before the onset of systole. Rapid inflation of the balloon increases diastolic aortic pressure by 25–70%, increasing end-organ and coronary perfusion. Rapid deflating of the balloon reduces native ventricular ejection pressure, reducing afterload and left ventricular external work.

[0015] Counterpulsation therapy is an attractive treatment option because the use of an IABP is much simpler than the implantation and use of an LVAD and is associated with fewer adverse events. For example, physicians can implant an IABP without directly cannulating the heart. However, conventional counterpulsation systems implanted through minimally invasive procedures can only be used for short periods of time. This is due to several reasons. For example, issues with arterial access (e.g., femoral artery), IABP durability, and biocompatibility can limit IABP use to short periods of less than approximately 14 days. Longer periods of IABP support (>14 days) can lead to increased incidence of vascular complications, infections, and bleeding. Furthermore, in its current form, the catheter-mounted IABP, which is advanced retrogradely from the femoral artery into the descending aorta, requires patients to remain supine throughout the treatment period. Therefore, patients cannot be made ambulatory or discharged from the hospital. These limitations have prevented IABP from being used as a long-term treatment for heart failure and instead are used in short-term settings, such as in patients awaiting transplant or undergoing coronary artery bypass surgery.

[0016] The present assignee / applicant (NuPulseCV, Inc.) has developed a variety of counterpulsation support systems designed to provide longer-term support to heart failure patients compared to the conventional systems described above. Such improved counterpulsation support systems are described in U.S. Patent No. 7,892,162, filed October 22, 2009, entitled "ARTERIAL INTERFACE," U.S. Patent No. 8,066,628, filed October 22, 2010, entitled "INTRA-AORTIC BALLOON PUMP AND DRIVER," U.S. Patent Application No. 15 / 685,553, filed August 24, 2017, entitled "BLOOD PUMP ASSEMBLY AND METHOD OF USE THEREOF," and U.S. Patent Application No. 16 / 876,110, filed May 17, 2020, entitled "INTRAVASCULARLY DELIVERED BLOOD PUMPS AND ASSOCIATED DEVICES, SYSTEMS, AND METHODS," the disclosures of each of which are incorporated herein by reference in their entirety.

[0017] The IABPs described in the incorporated disclosures provide long-term or chronic counterpulsation therapy for heart failure patients with components that, at least in certain circumstances, can be implanted using minimally invasive percutaneous techniques. For example, the IABPs can be minimally invasively implanted without entering the chest and generally do not require cardiopulmonary bypass or blood product administration.

[0018] The present technology provides a drive unit that can direct fluid (gas or liquid, e.g., air) into the interior volume of a balloon or expandable member (e.g., an IABP as described in the incorporated disclosures above) implanted within a patient's vasculature while minimizing mechanical inefficiencies that can cause mismatches between the inflation and de-inflation of the balloon and the patient's EKG, even in cases of arrhythmias such as atrial fibrillation, as described in more detail below.

[0019] Selected Aspects of Chronic Intravascular Circulatory Support Systems 1 illustrates a circulatory support and / or intravascular ventricular assist system 100 configured in accordance with an optional aspect of the present technology. System 100 may include an expandable member 110 implantable within the aorta of a heart failure patient. Expandable member 110 may also be referred to as an IABP or balloon. System 100 may further include a first pneumatic drive line 120 (also referred to as an "internal drive line"), an arterial interface device or stopper 130, a second pneumatic drive line 140, a skin interface device 190, a drive unit 150, and a sensor 160. System 100, when implanted, may provide counterpulsation therapy to a heart failure patient.

[0020] The expandable member 110 may be a balloon or other element that can change size and / or shape in response to being filled with a gas or liquid. For example, in some embodiments, the expandable member 110 is a balloon composed of a biocompatible, non-thrombogenic elastomeric material (e.g., Biospan®-S). The expandable member 110 may also be made of other suitable materials. The expandable member 110 is transitionable between at least a first generally de-inflated state and a second generally inflated state. The expandable member 110 has a first volume when in the first (e.g., de-inflated) state and a second volume when in the second (e.g., inflated) state that is greater than the first volume.

[0021] Thus, the expandable member 110 can provide counterpulsation therapy by repeatedly transitioning between a first state and a second state. To transition the expandable member 110 between the first state and the second state, the drive unit 150 may direct a fluid (gas or liquid, e.g., air) into the interior volume of the expandable member 110 via the first pneumatic drive line 120 and the second pneumatic drive line 140, as described in more detail below. The expandable member 110 may also be sized and / or shaped to reduce and / or prevent the expandable member 110 from blocking arteries branching from the aorta, such as the renal arteries. In some embodiments, the expandable member 110 may also have certain features generally similar to those described in the disclosures incorporated herein by reference. In some embodiments, the expandable member 110 includes an expandable end effector separate from or in addition to a balloon.

[0022] Drive unit 150 may generate gas flow into and out of extensible member 110 via first pneumatic drive line 120 and second pneumatic drive line 140, which converge to form external pneumatic drive line 172 extending from drive unit 150. For example, drive unit 150 may generate positive pressure to accelerate gas into extensible member 110 via first pneumatic drive line 120 and second pneumatic drive line 140, thereby inflating extensible member 110. Drive unit 150 may also induce negative pressure to withdraw gas from extensible member 110 via first pneumatic drive line 120 and second pneumatic drive line 140, thereby de-inflating extensible member 110. Drive unit 150 may induce gas flow into and out of extensible member 110 through a bellows (not depicted in FIG. 1 ). In some embodiments, drive unit 150 may control the volume of air forced into expandable member 110 to avoid over-inflating the expandable member 110. For example, in an embodiment utilizing a bellows to generate the airflow, the volume of the airflow generated by the bellows (e.g., the volume of the bellows) may correspond to the interior volume of the expandable member 110. Those skilled in the art will recognize that the volume of the bellows may not be the same as the interior volume of the balloon due to changes in relative pressure. In some embodiments, drive unit 150 uses ambient air (e.g., “room air”) from the environment surrounding drive unit 150 to power the operation of system 100. The use of ambient air is expected to reduce the size, weight, and / or cost of drive unit 150 compared to drive units that rely on an internal supply of gas or fluid (e.g., a helium tank). For example, in some embodiments, drive unit 150 may weigh approximately 3 kg or less. Also, in the event of a balloon leak or rupture, air is more likely to be absorbed into the blood compared to helium, reducing the risk of blood clots and stroke. The drive line may be disconnected near the skin interface device 190 when the system 100 is not in use and operational.

[0023] System 100 may enable chronic support of cardiac function and blood flow while still allowing the patient to remain ambulatory. Typical ventricular assist devices require femoral access for drive lines and / or connection to a large, stationary external control unit, thus confining the patient to a bed in a supine position for the duration of treatment. In contrast, system 100 allows the patient to move about relatively unhindered. Furthermore, the level of therapy provided by system 100 is adjustable to match the patient's needs. For example, the ratio of volume displacement and support provided by expandable member 110 (e.g., 1:1, 1:2, 1:3 support) can be adjusted for each patient to vary the support provided. Those skilled in the art will recognize that the ratio of support indicates the ratio of heartbeats to balloon inflations. For example, a support ratio of 1:1 indicates that there is a corresponding balloon inflation for every heartbeat, a support ratio of 1:2 indicates that there are two heartbeats before each inflation, and a support ratio of 1:3 indicates that there are three heartbeats before each inflation. Drive unit 150 may have a user interface (not depicted) that allows a user to control the volume displacement or support ratio. Alternatively, drive unit 150 may be controlled via other external inputs (e.g., using a compatible tablet or other device in electronic communication with drive unit 150). Gradually reducing volume displacement over time (e.g., by varying the desired stroke of the internal bellows mechanism as a percentage of total stroke) may result in controlled cardiac loading, which may be beneficial for cardiac recovery in some cases. Furthermore, unlike conventional circulatory support systems, system 100 can be turned off, such as to assess the patient's ability to handle cardiac demands without support before removing system 100, or for another suitable reason. For example, in some embodiments, expandable member 110 is designed to remain within the aorta in a de-inflated condition for a relatively long period of time (e.g., 23 hours per day). This contrasts with conventional devices.Conventional devices often must be removed if they are turned off for more than about 15 minutes, as emboli that formed during the inactive state can be flushed out when the device is reactivated.

[0024] Drive unit This disclosure contemplates at least two embodiments of drive unit 150. A first embodiment is depicted in Figures 2A-2F and refers to the drive unit by the reference numeral 200. A second embodiment is depicted in Figures 3A-3E and refers to the drive unit by the reference numeral 300.

[0025] 2A depicts a first embodiment of a drive unit 200. The drive unit 200 may include an outer case 202 having various ports 204. The ports 204 may be used for, among other things, a display readout, a power button, ventilation, and connectivity to other system components (e.g., pneumatic drive line 172).

[0026] 2B-2D, drive unit 200 may include an outer case 202 having an upper access plate 208 secured thereto using fasteners 206. Referring to FIGS. 2E-2F, drive unit 200 may include a bellows 220 and a motor 222 (e.g., an electric motor such as a brushless DC motor). The space to the left of bellows 220 in FIG. 2E may be at least partially occupied by electrical components (not shown) used to control motor 222. Such components may include one or more computer processors and memory containing computer processor-readable instructions executable by the computer processor. The same space may also be at least partially occupied by mechanical components such as a value manifold (e.g., for connecting bellows / pneumatic outputs 223 to appropriate ports 204).

[0027] Bellows 220 may be an axially extensible bellows that can expand and contract along the B-B axis depicted in FIG. 2E in response to motor 222 rotating in different directions. In the embodiment depicted in FIGS. 2E and 2F, bellows 220 expands such that expandable member 110 (FIG. 1) is de-inflated. When bellows 220 is compressed by motor 222, expandable member 110 (FIG. 1) is expanded. Bellows 220 may have a constant cross-sectional geometry along its length such that the volume within bellows 220 varies with the length of the bellows.

[0028] Motor 222 may include rotor 222a and stator 222b. Rotor 222a may be coupled to a rotary-to-linear converter. For example, rotor 222a may be coupled to a ball nut 224 carrying a ball screw 226 secured to a dynamic flange 228. Bellows 220 may be sealed by dynamic flange 228 at a first bellows end proximal to ball screw 226 and by static flange 229 (FIG. 3E) at a second bellows end distal to ball screw 226. Bellows outlet 233 (FIG. 3E) may allow fluid in external drive line 172 to communicate with extendable member 110 in response to movement of bellows 220.

[0029] In some embodiments, bellows outlet 233 may be formed in static flange 229. Ball screw 226 in combination with ball nut 224 may form a mechanical rotary-to-linear converter that converts rotary motion of motor 222 into linear motion with little friction. Rotation of ball nut 224 by rotor 222 a within stationary stator 222 b may move ball screw 226 linearly along axis BB, which may concomitantly cause linear motion of bellows 220.

[0030] The ball screw 226 may be threaded to provide a helical raceway 226a for the balls (not depicted) of the ball nut 224 and may act as a precision thread. Several dimensions may define the ball screw 226 and the raceway 226a. For example, the ball screw 226 may include a pitch that measures the distance between grooves in the helical raceway 226a.

[0031] The rotor 222a and ball nut 224 assembly may be mounted to a housing 230 of the motor 222 via a radial bearing 232. An inner race of the radial bearing 232 may be fixedly attached to the rotor 222a and ball nut 224 assembly, while an outer race of the radial bearing 232 and the stator 222b may be fixedly attached to the motor housing 230. Operation of the motor 222 may cause rotational motion of the rotor 222a and ball nut 224, which may advance the balls (not depicted) of the ball nut 224 within the helical races 226a of the ball screw 226 and convert the rotational motion of the rotor 222a into linear motion of the ball screw 226 along axis BB (FIG. 2E). The motion of ball screw 226 is transferred to bellows 220 via dynamic flange 228, which extends or contracts bellows 220, creating a negative or positive fluid flow, respectively, in external drive line 172, which is fluidly connected to extendable member 110 via bellows outlet 233 (FIG. 2E). In some embodiments, ball screw 226 may be fixedly mated to dynamic flange 228 via a threaded interface (as depicted in FIG. 2F). In some embodiments, dynamic flange 228 and ball screw 228 are one continuous piece. When ball screw 226 is fixedly mated to dynamic flange 228 or when ball screw 226 and dynamic flange 228 are one continuous piece, ball screw 228 may directly and efficiently transfer its motion to the bellows (e.g., when ball screw 226 is pulled back away from static flange 229, it may pull dynamic flange 228, extending bellows 220).

[0032] 2E-F and 4, drive unit 200 may include a processor 402, a memory 404, and drive unit 402. Processor 402 may include one or more dedicated or non-dedicated microprocessors, microcontrollers, sequencers, microsequencers, digital signal processors, processing engines, hardware accelerators, application-specific integrated circuits (ASICs), state machines, programmable logic arrays, any integrated circuit, discrete circuitry, or the like, or any suitable combination thereof, capable of processing data or information. Memory 404 may include any suitable non-volatile memory device, chip, or storage device, such as system memory, frame buffer memory, flash memory, random access memory (RAM), read-only memory (ROM), registers, and latches. Processor 402 may execute executable instructions (e.g., stored in memory 404). Processor 402 may be configured to control motor 222, and by extension, bellows 220.

[0033] For example, encoder disk 234 and encoder sensor 236 may determine the angular position, speed, and / or direction of the rotor and provide such information as a position feedback signal to processor 402 and / or memory 404. In other embodiments, a linear position sensor (not depicted) may be used to determine the position of ball screw 226 or bellows 220 and provide such a position feedback signal. Processor 402 and / or memory 404 may also receive control information from drive unit UI 406 and provide display information (e.g., status information) to drive unit UI 406. Relatedly, processor 402 and / or memory 404 may also receive EKG signals from skin interface device 190 and one or more sensors 160 (FIG. 1), one or more external control signals (e.g., from a tablet or other computing device (not depicted)), and one or more sensor signals. For example, processor 402 and / or memory 404 may receive pressure signals observed by a pressure sensor (not depicted) located near balloon 110 when placed within an artery (e.g., the descending aorta as depicted in FIG. 1) of a patient undergoing treatment (e.g., counterpulsation therapy). The one or more pressure signals may be indicative of the pressure exerted on balloon 110 within such artery and / or the pressure within such artery.

[0034] The processor 402 may use one or more of the position feedback signal, the drive unit UI 406 control signal, the EKG signal, the external control signal, and the sensor signal to control the motor 222. For example, the EKG signal may be used to ensure proper timing of inflation and / or de-inflation of the balloon 110 (e.g., to perform counterpulsation). And, as previously described, the drive unit UI 406 control signal and the external control signal may be used to vary the volume displacement and / or support ratio.

[0035] In other embodiments, a linear brushless DC motor, a solenoid, and / or a piezoelectric actuator may be used to compress and expand the bellows 220 .

[0036] To provide counterpulsation therapy in heart failure patients, drive unit 200 may be used to effectively inflate and deflate expandable member 110 using ambient air. The following component values, listed in the table below, may be efficient and / or economical for such purposes. The two columns of numbers represent dimensions suitable for counterpulsation using drive unit 200 and an approximately 20-60 cc balloon as expandable member 110. [Table 1]

[0037] While the drive unit 200 configured as described above is generally effective for counterpulsation, it uses a significant amount of power just to overcome the rotational inertia of the rotor 222a and may not be “fast enough” to treat patients with arrhythmias, irregular heartbeats, or a-fib. The pitch of the ball screw may be selected or adjusted to improve the efficiency of the drive unit. Specifically, adjusting the pitch of the ball screw (and / or adjusting the diameter of the bellows 220) may better match the impedance of the motor 222 to the impedance of the pneumatic load on the drive unit 200 (e.g., the collective pneumatic load of the balloon 110, first pneumatic drive line 120, second pneumatic drive line 140, and external drive line 172). Such improved efficiency may improve the life of any batteries used in the drive motor 222.

[0038] 3A, a second embodiment of a drive unit 300 may also include an outer case 302 having various ports 304. The ports 304 may be used for, among other things, a display readout, a power button, ventilation, and connectivity to other system components (e.g., pneumatic drive line 172).

[0039] 3B-3D, outer case 302 may include end access plate 308 securely secured thereto. Referring to FIG. 3E, drive unit 300 may include bellows 320 and motor 322 (e.g., an electric motor such as a brushless DC motor). Bellows 320 may be an axially-extending bellows that can extend and contract along the DD axis depicted in FIG. 3E in response to motor 322 rotating in different directions. As depicted in FIG. 3E, bellows 320 may include dynamic flange 328. Dynamic flange 328 may be sized and shaped to receive or house at least a portion of motor 322 such that at least a portion of motor 322 is nested within bellows cavity 320a. For example, recess 328a may be oriented toward bellows cavity 320 and may have a three-dimensional shape (e.g., cylindrical) suitable for receiving or housing and nesting at least a portion of motor 322 within bellows cavity 321a while maintaining a stroke length sufficient to provide effective airflow within external drive line 172. Recess 328a may allow for a reduction in size and weight of outer case 302 (e.g., compared to the size of outer case 202), which may improve the mobility of the system. In the embodiment depicted in FIG. 3E, bellows 320 is depicted in an extended or uncompressed state such that extendable member 110 (FIG. 1) is de-inflated.

[0040] The motor 322 includes a rotor 322a and a stator 322b. Similar to the first embodiment 200, the rotor 322a may be configured to mate with a rotary-to-linear converter, such as a ball nut 324 carrying a ball screw 326 secured to a dynamic flange 328 via a threaded interface. In other embodiments, the rotor 323a and ball nut 324 may be formed as a single piece. In some embodiments, the ball screw 326 is hollow to reduce weight. The rotor 323a and ball nut 324 assembly may be mounted to the motor housing 332 via a radial bearing 330. The inner race of the radial bearing 330 may be secured to the rotor 323a and ball nut 324 assembly, while the outer race of the radial bearing 330 and the stator 323b may be secured to the motor housing 332. Similar to the first embodiment, operation of motor 322 may cause rotational motion of rotor 323a and ball nut 324, which may translate into linear motion of ball screw 326 along axis DD. Motion of ball screw 326 may be translated to bellows 320 via dynamic flange 328, which extends or contracts bellows 320, creating negative or positive fluid flow, respectively, in external drive line 172, which is fluidly connected to extendable member 110 via bellows output / pneumatic output 333 associated with static flange 329. In other embodiments, a linear brushless DC motor, solenoid, and / or piezoelectric actuator may be used to compress and extend bellows 320.

[0041] Ball screw 326 may be fitted to dynamic flange 328 (or the two components may be one continuous piece) to allow ball screw 328 to directly and efficiently transfer its motion to bellows 320 while rotor 322a and ball nut 324 spin about axis DD within stator 322b. Rotation of rotor 322a may carry the balls of ball nut 324 within helical tracks 226a of ball screw 226, thus causing motion of ball screw 226 along axis DD.

[0042] 2E-F and 4, encoder disk 334 and encoder sensor 336 may determine the angular position, speed, and / or direction of the rotor and may provide such information to a processor via an electrical feedback signal (not depicted). In other embodiments, a linear position sensor (not depicted) may be used to determine the position of ball screw 326 or bellows 320 and provide that information to such a processor. Such a processor may also receive EKG signals from skin interface device 190 and one or more sensors 160 (FIG. 1), suitable external control signals (e.g., from a tablet (not depicted) configured to control motor 322 and the stroke of bellows 220, a user interface operatively coupled to case 302 (not depicted), etc.), and other sensors (e.g., a pressure sensor (not depicted) capable of sensing pressure in the descending aorta).

[0043] Drive unit 300 may be used to effectively inflate and de-inflate expandable member 110 using ambient air to provide counterpulsation therapy in heart failure patients, including those with arrhythmia, irregular heartbeat, or a-fib. The following ranges of component values ​​may be efficient and / or economical for counterpulsation using drive unit 300 and an approximately 20-60 cc balloon as expandable member 110: [Table 2]

[0044] 3E and 4, the drive unit 300 may include a processor 402, a memory 404, and a drive unit 402. The encoder disk 334 and the encoder sensor 336 may determine the angular position, speed, and / or direction of the rotor and provide such information as a position feedback signal to the processor 402 and / or memory 404. In other embodiments, a linear position sensor (not depicted) may be used to determine the position of the ball screw 326 or the bellows 320 and provide such a position feedback signal. The processor 402 and / or memory 404 may also receive control information from the drive unit UI 406 and provide display information (e.g., status information) to the drive unit UI 406. Relatedly, the processor 402 and / or memory 404 may also receive EKG signals from the skin interface device 190 and one or more sensors 160 (FIG. 1), one or more external control signals (e.g., from a tablet or other computing device (not depicted)), and one or more sensor signals. For example, processor 402 and / or memory 404 may receive pressure signals observed by a pressure sensor (not depicted) located near balloon 110 when placed within an artery (e.g., the descending aorta as depicted in FIG. 1) of a patient undergoing treatment (e.g., counterpulsation therapy). The one or more pressure signals may be indicative of the pressure exerted on balloon 110 within such artery and / or the pressure within such artery.

[0045] The processor 402 may use one or more of the position feedback signal, the drive unit UI 406 control signal, the EKG signal, the external control signal, and the sensor signal to control the motor. For example, the EKG signal may be used to ensure proper timing of inflation and / or de-inflation of the balloon 110 (e.g., to perform counterpulsation). And, as previously described, the drive unit UI 406 control signal and the external control signal may be used to vary the volume displacement and / or support ratio.

[0046] Assuming that drive unit 200 and drive unit 300 are configured to move the same amount of air (i.e., to deflate or inflate the same size balloon) when corresponding bellows 220, 320 undergo linear motion from a fully extended position to a fully retracted position, or vice versa, drive unit 300 may have several advantages over drive unit 200. For example, drive unit 300 may be configured to be smaller and lighter (i.e., have a smaller volumetric enclosure) than drive unit 200, which may have a significant impact on the ability of a person who must carry drive unit 150 to be mobile / engage in more ambulatory activities. In particular, bellows 320 may have a smaller bellows travel distance (and a shorter ball screw) than drive unit 220. By increasing the bellows diameter in drive unit 300 relative to the bellows diameter in drive unit 200, (1) the impedance of the pneumatic load on the drive unit (e.g., the collective pneumatic load of balloon 110, first pneumatic drive line 120, second pneumatic drive line 140, and external drive line 172) is better matched to the impedance of the motor (i.e., the mechanical subsystem of the drive unit), and (2) the power consumption required for inflation and deflation is reduced, thereby increasing the efficiency of drive unit 300 compared to drive unit 200.

[0047] In such a configuration, the overall dimension of drive unit 300 along its axis of linear motion (i.e., axis DD) may be smaller than the overall dimension of drive unit 200 along its axis of linear motion (i.e., axis BB). The longest dimension of drive unit 200 may be along its axis of linear motion (i.e., axis BB), while the longest dimension of drive unit 300 may be perpendicular to its axis of linear motion (i.e., perpendicular to axis DD). This may be particularly true when both outer cases 202 and 302 are cuboid (or substantially cuboid in shape) and configured such that the faces of static flanges 229, 329 are parallel to the faces of outer cases 202, 302. As depicted in FIG. 3E, the longest dimension of drive unit 300 may correspond to an axis parallel to the diameter of bellows 320.

[0048] Additionally, the drive unit 300 design may be configured to operate fast enough to de-inflate the corresponding balloon or expandable member 110 by 50% within approximately 100 ms of the R wave in the QRS complex to treat patients with irregular heart rhythms (e.g., patients with atrial fibrillation, or "a-fib"). As discussed above, a-fib is an irregular and / or fast heart rate that occurs when the two upper chambers of the heart receive disorganized electrical signals. This results in a fast, irregular heart rhythm that is difficult to predict for effectively inflating and de-inflating the expandable member 110. To effectively treat a-fib patients, the expandable member 110 should de-inflate by at least 50% within approximately 100 ms of the R wave. Without rapid de-inflation, the expandable member 110 may obstruct blood flow within the aorta, increasing the heart's workload. To use the R wave within the QRS complex as an indicator of ventricular contraction, the EKG signal must be processed to locate the R wave, which can take approximately 20-50 ms using conventional algorithms and processors, depending on the algorithm used. By setting the ball screw pitch in drive unit 300 to 3.5-5.5 mm and using a bellows 320 with an outer diameter of 125-111 mm and an effective bellows stroke of 8.0-11.5 mm, drive unit 300 may be able to effectively treat patients with irregular heartbeats and a-fib.

[0049] Additionally, drive unit 300 can be much more efficient in terms of power consumption than drive unit 200, thereby increasing the battery life of the battery (not depicted) powering motor 322 compared to the battery (not depicted) powering motor 222, assuming the batteries are the same. In particular, motor 222 can inefficiently use a disproportionate amount of power to overcome the rotational inertia of rotor 222a in drive unit 200 compared to the amount of power utilized in drive unit 300 to overcome the rotational inertia of rotor 322a. Drive unit 300 achieves this advantage by: (a) setting the pitch of the ball screw in drive unit 300 so that the impedance of motor 322 is the same or substantially the same (i.e., matches or substantially matches) the impedance of the pneumatic load on drive unit 300; and / or (b) using an enlarged bellows 320, which allows for a design with reduced bellows travel (and may further help match or substantially match the impedance of motor 322 to the pneumatic load on drive unit 300).

[0050] The tables provided above for drive unit 200 and drive unit 300 are exemplary only. Drive units with different component values ​​are also contemplated as being within the scope of this disclosure.

[0051] conclusion The above detailed description of the various aspects of the present technology is not intended to be exhaustive or to limit the present technology to the precise form disclosed above. While specific aspects and examples of the present technology have been described above for illustrative purposes, various equivalent modifications are possible within the scope of the present technology, as will be recognized by those skilled in the art. The various aspects described herein may also be combined to provide further aspects.

[0052] Unless the context clearly requires otherwise, throughout the description and examples herein, words such as "comprise" and "comprising" should be construed in an inclusive sense, i.e., "including, but not limited to," rather than an exclusive or exhaustive sense. As used herein, "connected," "coupled," or variants thereof, mean any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between elements may be physical, logical, or a combination thereof. In addition, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to particular portions of this application. Where the context permits, words using the singular or plural form in the above detailed description may also include the plural or singular form, respectively. As used herein, the phrase "and / or," as in "A and / or B," refers to A alone, B alone, and A and B in combination. It will also be recognized that specific embodiments are described herein for illustrative purposes, but that various modifications may be made without departing from the technology. Furthermore, while advantages associated with some embodiments of the technology are described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments necessarily exhibit such advantages to fall within the scope of the technology. Thus, the present disclosure and related technology may encompass other embodiments not explicitly delineated or described herein.

Claims

1. A drive unit for controlling an extendable member in an intravascular circulatory support system, comprising: A motor and a bellows having a first end, a second end, and a bellows cavity located between the first end and the second end, the bellows configured to contract the expandable member by at least 50% within about 100 milliseconds (ms) of receiving an R wave of a QRS complex detected in an electrocardiogram (EKG) signal of a patient receiving treatment.

2. The motor includes a rotor and a stator disposed in a motor housing; The drive unit of claim 1 , wherein the stator is fixed to the motor housing.

3. A ball nut including a plurality of balls; 3. The drive unit of claim 2, comprising: a ball screw, wherein the ball nut is fixed to a rotor, the ball screw including a helical track, and the plurality of balls are configured to progress within the helical track due to rotation of the rotor, the plurality of balls translating the rotation into linear motion of the ball screw within the ball nut.

4. The device further includes a static flange disposed at the first end of the bellows, a dynamic flange disposed at the second end of the bellows, and an outer case having an inner surface; 2. The drive unit of claim 1, wherein the static flange is secured to the inner surface of the outer case and configured to seal the first end, the dynamic flange is configured to seal the second end, and the static flange includes an output portion configured to allow air to pass through for expansion and contraction of the extendable member.

5. Configured to determine one or more of the angular position, speed, and direction of a rotor; and 3. The drive unit of claim 2, further comprising an encoder disk and an encoder sensor configured to generate one or more position feedback signals based on one or more of the determined rotor angular position, speed, and direction.

6. A drive unit as described in claim 5, further comprising a processor configured to control the motor based on at least the one or more position feedback signals.

7. A drive unit as described in claim 6, wherein the processor is further configured to control the motor based on the EKG signal.

8. A drive unit as described in claim 1, wherein the outer diameter of the bellows is within the range of approximately 111 mm to 125 mm.

9. A drive unit as described in claim 1, wherein the travel distance of the bellows is within the range of approximately 8 mm to 11.5 mm.

10. A drive unit as described in claim 2, wherein the diameter of the bellows is configured so that the impedance of the motor corresponds to the impedance of the pneumatic load on the drive unit.

11. A drive unit as described in claim 1, wherein the outer diameter of the bellows is within the range of approximately 111 mm to 125 mm, and the stroke distance of the bellows is within the range of approximately 8 mm to 11.5 mm.

12. A drive unit as described in claim 1 configured to provide counterpulsation therapy to a patient.

13. A drive unit for controlling an extensible member in an intravascular circulatory support system, comprising: a motor including a rotor and a stator; a bellows having a first end, a second end, and a bellows cavity located between the first end and the second end; a housing that accommodates the motor and the bellows; a first end of the bellows coupled to a static flange and a second end of the bellows coupled to a dynamic flange, the dynamic flange configured to impart a movement to the bellows that expands and contracts the bellows; A drive unit wherein the outer diameter of the bellows is within a range of approximately 111 mm to 125 mm, and the stroke of the bellows is within a range of approximately 8 mm to 11.5 mm.

14. A drive unit as described in claim 13, wherein the stator is fixed to the housing.

15. A ball nut fixed to the rotor and including a plurality of balls; 14. The drive unit of claim 13, comprising: a ball screw including a helical track, the plurality of balls configured to progress within the helical track due to rotation of a rotor, the plurality of balls translating the rotation into linear motion of the ball screw within a ball nut.

16. A drive unit as described in claim 15, wherein the pitch of the spiral track is in the range of approximately 3.5 mm to 5.5 mm so that the impedance of the motor is the same or substantially the same as the impedance of the pneumatic load on the drive unit.

17. A rotor control system configured to determine one or more of the angular position, speed, and direction of a rotor; and 14. The drive unit of claim 13, further comprising an encoder disk and an encoder sensor configured to generate one or more position feedback signals based on one or more of the determined rotor angular position, speed, and direction.

18. The method of claim 1, further comprising: a processor configured to control the motor based on at least the one or more position feedback signals; The drive unit of claim 16, wherein the processor is further configured to control the motor based on an EKG signal.

19. A drive unit for controlling an extensible member in an intravascular circulatory support system, comprising: a motor including a rotor and a stator; a bellows having a first end, a second end, and a bellows cavity located between the first end and the second end; a drive unit configured to move air in and out of the output portion by expanding and contracting the extendable member when operated by the motor; a first end fixed to the motor and including an output portion; and a second end coupled to a dynamic flange having a recess facing the bellows cavity, the recess configured to receive at least a portion of the motor within the bellows cavity; the bellows configured to be operated by the motor and to expand and contract the extendable member to move air in and out of the output portion.

20. A drive unit as described in claim 19, wherein the shape of the recess in the dynamic flange is cylindrical.

21. A drive unit as described in claim 19, wherein the recess is configured to accommodate at least a portion of the rotor and at least a portion of the stator.

22. The motor includes a rotor disposed in a motor housing and a stator; 20. The drive unit of claim 19, wherein the stator is fixed to the motor housing.

23. A drive unit as described in claim 19, wherein the bellows cavity has a constant cross-sectional area.

24. A drive unit as described in claim 19, wherein the recess extends laterally across the entire width of the cavity.

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