Devices, systems, and methods for percutaneous and synchronized cardiac assistance

Abstract

A heart assist system includes a pneumatic actuator implanted below the pericardial sac and above the surface of the myocardium covering the patient's left ventricle. A port is implanted and receives a cannula introduced percutaneously. The port is connected to supply drive gas received from the cannula to the pneumatic actuator. An external drive unit includes a pump assembly and a control circuit that operates the pump to actuate the pneumatic actuator in response to a sensed heart rhythm of the patient. A connecting tube has a pump end connected to the pump and a percutaneous port connection end attached to the implantable port.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent No. 62 / 810,866, filed February 26, 2019 (Attorney Docket No. 56027-703.101), which is incorporated herein by reference in its entirety. Background Art

[0003] 1. Technical Field. The present invention generally relates to medical devices, systems, and methods. More specifically, the present invention relates to systems for providing cardiac assistance to patients with advanced heart failure.

[0004] A variety of ventricular assist devices (VADs) have been proposed for supporting blood circulation in patients with severe heart failure. VADs are also used to keep patients alive until a donor heart is available for transplant, serving as a "bridge to transplant." In the United States, up to 50,000 patients require a heart transplant each year due to end-stage heart failure. Donor hearts are only available for 2,000 to 2,500 patients each year. Many patients who are unable to receive a transplant can survive by receiving a VAD.

[0005] However, the placement of currently available VADs (typically sternotomy or thoracotomy) generally requires a large surgical incision. It is difficult for patients with heart failure to undergo such a large surgical procedure. Although many minimally invasive VADs have been proposed, such as intravascular rotary pumps and external compression devices, such minimally invasive systems generally require a large percutaneous "umbilical cord" to provide power to drive the implanted pump auxiliary components. Such cords are inconvenient, uncomfortable, and present a high risk of infection. In addition, when infected, removing the large umbilical cord generally requires surgical intervention.

[0006] For these reasons, it is desirable to provide improved devices, systems, and methods for providing cardiac assistance to patients with advanced heart failure. It would be particularly desirable to provide such systems that can be implanted via subxiphoid and other established minimally invasive approaches. It would also be desirable to provide VAD systems with percutaneous connectors that reduce the risk of infection and are easier to replace and sterilize if they become infected. The invention described and claimed herein will satisfy at least some of these needs.

[0007] 2. Description of Background Art. Relevant patents and publications include US2019 / 0076250; US2008 / 0275295; US2007 / 0073218; US10391216; US10220128; US9259318; US8092363; US7468029; US6602182; US6432039; US6238334; US5713954; US4957477; and WO1998 / 005289. Summary of the Invention

[0008] The present invention provides a minimally invasive cardiac assist device for patients suffering from heart failure or other impaired cardiac function. The device includes an implantable cardiac assist catheter, which is typically configured to be advanced over a guidewire into the patient's pericardial sac at a position between the myocardial surface and the inner surface of the pericardium. The implantable cardiac assist catheter has a balloon or other pneumatic actuator at its distal end, and an external drive unit is usually provided to synchronize the inflation of the balloon with the ventricular contraction of the patient's natural cardiac cycle, thereby compressing the heart and providing ventricular assist, thereby increasing the patient's cardiac output. The relative inflexibility of the fibrous pericardial sac provides a restrictive constraint, causing the inflated balloon to compress the ventricles. In addition, the sternum also covers the heart and provides a bony shell to enhance cardiac compression when the balloon is inflated. The cardiac assist device can be used with a sensor to obtain an electrocardiogram signal for synchronizing balloon inflation.

[0009] An intrapericardial cardiac assist catheter can be anchored solely at the pericardial entry point. Alternatively, it can enter the pericardium near the apex and exit the pericardium further superiorly, toward the base of the heart. Near the distal tip of the catheter, an expansion anchor, such as a small balloon, can be located outside the pericardium and maintain the position of the ventricular compression balloon. The ventricular compression balloon can be elliptical in shape and its length can extend along the majority of the ventricular cavity. The ventricular compression balloon can be inflated with a fluid (gas or liquid, typically gas) to reduce inflation / deflation time. Gas is preferred because it allows for rapid response times for balloon inflation and deflation. The frequency of balloon inflation should be equal to the physiological heart rate, approximately 70 bpm. A small reservoir can be attached to the proximal end of the catheter. One surface of the reservoir can contain a septum or other elastic portion through which a needle can be inserted for balloon inflation, while simultaneously sealing against the inserted needle. Alternatively, the entire reservoir can be constructed of a self-sealing, needle-pierceable elastic material. After the catheter is placed, the reservoir can be implanted subcutaneously through a small skin incision, cardiac assistance, and orientation so that the elastic surface faces the skin. The balloon catheter and attached subcutaneous reservoir remain implanted, while the inflation pump, controller, and battery are located outside the patient's skin, with a percutaneous needle used to inflate and deflate the ventricular compression balloon through the implanted reservoir. This configuration facilitates replacement of the pump and battery while reducing the likelihood of catheter infection because the small diameter needle passes through the skin. The needle puncture site can also be changed regularly to reduce the likelihood of needle tract infection.

[0010] The ventricular compression balloon can be inflated and deflated with the aid of an external battery-operated pump located outside the patient's body. The pump can be bidirectional with a fluid reservoir attached; or in the case of ventricular compression balloon inflation, the inlet and outlet of the pump can be directly connected to the room air. Ventricular compression balloon inflation is synchronized with the cardiac cycle with the aid of an electronic sensor that senses the patient's ECG (electrocardiogram) signal and initiates balloon inflation at the start of the QRS complex. Patient ECG sensing can be performed via a conductive needle from an external unit that pierces the patient's skin to perform balloon inflation. Alternatively, ECG electrodes or other sensors can be provided in an implantable port and / or catheter, and the needle is used to provide a connection to the ECG circuit in the external controller. A control unit in the external pump module receives the ECG signal and triggers balloon inflation during systole. During diastole, active balloon deflation is performed by the pump. Balloon inflation can also be performed using a hydraulic system containing a pressurized fluid tank that provides balloon inflation during systole and a pressure relief valve that allows the balloon to deflate during diastole. The fluid tank can be re-pressurized periodically, or a battery-operated compressor can be part of a unit located outside the patient's body.

[0011] Although a percutaneous approach is described above, the ventricular compression balloon device can be inserted via a minimally invasive surgical approach using a small 4 cm subxiphoid incision to enter and puncture the pericardium near the apex of the heart. A guidewire and tapered dilator can be inserted into the pericardial space in front of the heart at the apex and advanced to a higher position on the left side of the pericardium to exit the pericardium. The dilator can then be removed from the patient, and the ventricular compression balloon catheter can be advanced over the guidewire to a position across the left ventricle for cardiac assistance.

[0012] In some embodiments, a percutaneous ventricular assist device can include a balloon catheter that is inserted into the patient's pericardium near the apex of the heart via a subxiphoid puncture site. A reservoir containing an elastic face is attached to the proximal end of the catheter. A 4 cm incision is performed to extend the subxiphoid puncture site, and the reservoir is implanted subcutaneously in the epigastric region of the abdominal wall. In such devices, a single needle penetrates the patient's skin and the elastic face of the reservoir to allow a pump unit external to the patient to inflate and deflate the balloon catheter, thereby compressing the patient's ventricle during systole. Balloon inflation is triggered by the patient's ECG, as sensed in real time.

[0013] Acquiring an ECG signal requires at least two electrodes. In previous devices, an inflatable needle formed one electrode, and the second electrode consisted of a surface electrode with an adhesive patch for skin attachment to the patient's abdomen or chest. ECG signals obtained from a needle inserted through body tissue are superior to those obtained from a surface electrode because needles are less susceptible to motion artifacts and noise than surface electrodes. The proposed design integrates one, two, or more electrodes into an implantable reservoir, with a conductive mesh extending from each electrode to provide an expandable target to accommodate needle placement. The size of the opening in the mesh is an interference fit with the circumference of the needle; when the needle is inserted, the mesh applies pressure against the outer surface of the needle, ensuring optimal ECG signal conduction. The needle can contain a series of knobs or barbs to facilitate anchoring in the mesh component of the target electrode, preventing inadvertent needle removal.

[0014] The reservoir body can be constructed from an implantable polymer material, such as polycarbonate or polyvinyl chloride. The electrodes can be constructed from a conductive metal, such as stainless steel. If a single electrode is incorporated into a single reservoir, it can be a metal ring attached to the outer diameter of the polymer reservoir. If two electrodes are incorporated into a single reservoir, one electrode can be attached to the outer diameter of the reservoir, and the other electrode can be a smaller-diameter concentric metal ring attached to the elastic surface of the reservoir. A stainless steel mesh can extend radially inward from the outer electrode toward the inner electrode, with a circumferential gap between the inner edge of the mesh and the outer edge of the inner electrode, acting as an insulator between the two electrodes. Alternatively, the two electrodes can be formed from two diametrically opposed arcs on the outer diameter of the reservoir, with the steel mesh extending between the ends of each arc, thereby leaving a non-conductive region between the two conductive mesh areas. Combinations of multiple electrodes on multiple reservoirs can be used; for example, two electrodes can be located on one implanted reservoir and a single electrode on a second implanted reservoir to create a three-lead EKG sensing array.

[0015] In another embodiment of the present invention, a circuit board that receives EKG signals and controls activation of an external pump unit is located in the reservoir. Signals from the control board are transmitted to the external pump unit via fiber optic transmission, ensuring minimal signal noise due to patient movement. A fiber optic connection consisting of a circular array surrounding one of the inflation needles mates with a corresponding circular array in the circuit board. A funnel guide is incorporated into the inner concentric electrode of the reservoir to ensure that needle insertion results in engagement of the corresponding fiber optic array on the needle and the control board in the reservoir. The two needles inserted through the mesh electrode carry current from the external unit to power the circuit board in the reservoir.

[0016] In a first aspect, the present invention provides a heart assist system comprising a pneumatic actuator configured to be implanted beneath a patient's pericardial sac and above the surface of the myocardium, typically overlying the patient's left ventricle. The system further comprises an implantable port configured to receive a percutaneously introduced cannula, wherein the cannula supplies a driving gas to the pneumatic actuator. Typically, the pneumatic actuator can be a balloon positioned near the distal end of a catheter or other tubular body, wherein the implantable port is connected to the catheter or other tube near the proximal end.

[0017] The heart assist system also includes an external drive unit comprising a pump assembly and a control circuit. The pump assembly comprises at least one pump for delivering a gas (typically ambient air) to the cannula. The control circuit is typically configured to operate the pump to actuate the pneumatic actuator in response to a sensed heart rhythm of the patient. Typically, the connecting tube has a pump end that is connectable to the pump of the pump assembly and a cannula end that is attached to the cannula.

[0018] In certain embodiments, the pneumatic actuator may include an inflatable balloon, such as a medical balloon, typically a non-inflatable medical balloon on a catheter, wherein the balloon is configured to be positioned above the patient's left ventricle and below the inner surface of the pericardial sac. When fully inflated, the balloon will typically have a volume in the range of 50 ml to 200 ml, typically in the range of 76 ml to 125 ml. In other cases, the pneumatic actuator may include some other pneumatically actuated mechanical device, such as a piston and cylinder device.

[0019] In other examples and embodiments of the invention, the implantable port may include a needle-penetrable septum wherein the cannula comprises a needle or other sharp tube or hollow probe configured to percutaneously penetrate patient tissue (typically the abdominal wall) overlying the septum and further penetrate the septum to fluidly connect the pump assembly and external drive unit to the interior of the port so that air or other gas can be delivered under pressure to inflate or otherwise actuate the pneumatic actuator.

[0020] In certain circumstances, the septum will have a sufficiently large area to provide multiple sites for needle penetration. This is a particular advantage when the percutaneous insertion site becomes infected. By having multiple needle penetration sites, the needle can be removed from the infected area of ​​the patient being treated, and a new or sterilized needle can be introduced into the implantable port through an alternate site on the septum. In this way, neither the implantable port nor the pneumatic actuator need to be removed or otherwise significantly disturbed in order to treat the infection.

[0021] However, in alternative embodiments, the implantable port may include a mechanical valve for receiving a needle or other cannula. Such mechanical ports are well known for hemodialysis access and other purposes. For example, see US 6,120,492, the entire disclosure of which is incorporated herein by reference.

[0022] In other embodiments, the system of the present invention will also include at least one electrocardiogram (ECG) electrode, which is positioned and configured to detect the patient's heart rhythm. As with conventional ECG detection systems, the ECG electrodes can be located externally and can include one, two, three, four or more external electrodes. However, conveniently, one or more ECG electrodes can be incorporated into the heart assist system. For example, the electrode can be provided by or incorporated into the needle or other cannula for entering the implantable port. Alternatively or additionally, one or more ECG electrodes can be located at or coupled to the implantable port itself. For example, one, two, three, four or more ECG electrodes can be attached to the outer surface of the port housing, the port diaphragm or other membrane, or other places on the port. Further alternatively or additionally, one or more ECG electrodes can be located on the connecting tube and / or on the pneumatic actuator itself.

[0023] In systems with ECG electrodes, the external drive unit will typically also include ECG circuitry to detect heart rhythm and synchronize actuation of the pump assembly with the heart rhythm. When ECG electrodes are present on any portion of the implantable port or connecting tubing, electrical conductors can be disposed in or through a needle or other cannula to deliver electrical signals to the ECG circuitry. When the needle or other cannula itself includes ECG electrodes, the needle or other cannula can be connected to the ECG circuitry via conductors in a catheter or other structure that connects the cannula to the external electrodes. Conventional external ECG electrodes can be connected to an external controller via conventional ECG leads.

[0024] The control circuit in the external drive unit will typically be configured to actuate the pneumatic actuator in synchronization with the patient's heart rhythm as measured by the ECG. For example, the control circuit can be configured to actuate the pneumatic actuator each time an R-wave peak occurs. Typically, the control circuit will be further configured to detect an abnormal heart rhythm. For example, the control circuit can compare the time between consecutive individual R-peaks and determine the presence of an abnormal heart rhythm based on an increase or decrease in time exceeding a predetermined threshold percentage, such as 300%, typically 250%. Alternatively or additionally, the control circuit can compare the time between consecutive cumulative R-peaks and determine whether an abnormal heart rhythm is present based on a total variability exceeding a predetermined threshold percentage (typically 300%, typically 250%).

[0025] When the control circuit detects an abnormal heart rhythm, it can take any of several actions. For example, the control circuit may simply cease actuation of the pneumatic actuator until the heart rhythm returns to a normal pattern. Alternatively, the control circuit may actuate the pneumatic actuator at a predetermined fixed rate, typically ranging from 50 beats per minute (bpm) to 80 bpm, and continue such actuation until a normal heart rhythm is reestablished. Further alternatively, the control circuit may be configured to actuate the pneumatic actuator at a rate that is modified "proportionally" relative to the patient's heart rhythm when an abnormal heart rhythm is detected. That is, while actuation of the pneumatic actuator is typically at a 1:1 ratio when the heart rhythm is normal, this ratio may be changed to another ratio when an abnormal heart rhythm is detected. For example, if a patient experiences an abnormally high heart rate (tachycardia), the rate at which the pneumatic actuator is triggered may be reduced. The pneumatic actuator may be triggered once every two heartbeats (1:2), once every three heartbeats (1:3), and so on.

[0026] In yet other embodiments, the pump assembly of the heart assist system can be configured to alternately deliver drive gas to and extract drive gas from the pneumatic actuator. Each delivery and extraction cycle will correspond to a single trigger event from a control circuit of an external controller. The cycle of pump delivery and pump extraction will correspond to the patient's heart rate detected from the ECG, with a single cycle typically lasting about one second for a patient with a heart rate of 60 bpm. It will be understood that such rapid inflation and deflation requires a fast-acting system, and the available gas transfer volume, fluid transfer chamber size, etc. will need to conform to the required inflation and deflation times. In order to achieve fast delivery and extraction times, the fluid being delivered is typically a gas, usually ambient air.

[0027] The pump assembly can take any of a variety of configurations for delivering and withdrawing fluid to the pneumatic actuator. For example, the pump assembly can include a single pump that operates in a single flow direction and also includes the valves required to divert gas from the inflation direction to the deflation direction. Alternatively, the pump assembly can include a pair of pumps, one operating in the fluid delivery direction and the other operating in the fluid withdrawal direction. It should also be understood that the pump assembly can be connected to a single cannula that provides fluid delivery and fluid withdrawal from the implantable pump. Alternatively, the pump assembly can be connected to a pair of cannulas, one for delivering the inflation fluid and one for withdrawing the inflation fluid.

[0028] In a second aspect, the present invention provides a method for assisting cardiac function in a patient suffering from heart failure. The method may include monitoring the patient's ECG to determine heart rhythm. An implanted port in the patient is accessed percutaneously via a cannula, and a drive gas is delivered through the cannula to the connected port and then to a pneumatic actuator implanted in the patient's left ventricle. The delivery and withdrawal of the drive gas is synchronized with the sensed heart rhythm, causing the pneumatic actuator to compress the heart at a rate that generally matches the patient's natural heart rhythm.

[0029] In certain embodiments, the pneumatic actuator will be implanted below the patient's pericardial sac and above the myocardial surface. In further certain embodiments, the pneumatic actuator will be on a cardiac assist catheter that enters through the pericardium at an entry location and, in some cases, has a distal tip that exits through the pericardium at an exit location. An anchor (such as a small anchoring balloon) may be provided on the distal tip of the cardiac assist catheter to stabilize the pneumatic actuator at a desired location in the pericardial sac.

[0030] In another specific embodiment, ECG can be detected in a variety of ways. For example, one or more ECG electrodes can be located on an implanted port, on an implanted pneumatic actuator, or elsewhere on the implanted portion of the system. In such cases, a cannula can be used as a percutaneous transmission element or conductor to deliver the signal from the implanted ECG electrode to the ECG circuit in the external controller. In other specific embodiments, the cannula or multiple cannulas can themselves serve as ECG electrodes after they are percutaneously introduced into the implanted port. In other specific embodiments, ECG signals can be measured by one or more external electrodes attached to the patient in a conventional manner. It should be understood that a single-channel ECG can be used, but preferably, at least a dual-channel ECG, preferably a three-channel ECG, a four-channel ECG or larger, will be used. Electrodes can also be placed on an implanted pneumatic actuator to provide cardiac pacing in the event of a patient's bradycardia, or to provide cardiac defibrillation in the event of a patient experiencing ventricular tachycardia, ventricular fibrillation, or cardiac arrest.

[0031] The method of the present invention also includes optionally detecting an abnormal heart rhythm. The abnormal heart rhythm will be determined based on the measured ECG, and the presence of an abnormal heart rhythm will typically result in stopping or modifying the operation of the pneumatic actuator. For example, when an abnormal heart rhythm is detected, the driving gas can be stopped. Alternatively, when an abnormal heart rhythm is detected, the delivery rate of the driving gas can be changed. In particular, in the presence of a rapid heartbeat (tachycardia), the driving rate may be reduced, or in the presence of a slow heartbeat (bradycardia), the driving rate may be increased.

[0032] The methods of the present invention also include protocols for treating patients in the event that the tissue access site is infected. In such cases, the needle or other cannula can be withdrawn from the tissue tract, the tissue tract treated for infection, and the cannula (sterilized or a new one) can be reintroduced into the implant port, typically through a different access path. For example, with a septum-type port, the cannula can be introduced into a different area of ​​the portion through a new tissue tract in uninfected tissue.

[0033] In a third aspect, the present invention provides an implantable cardiac assist catheter for use with an external drive unit, the implantable cardiac assist catheter comprising a catheter body having a proximal end and a distal end. A pneumatic actuator is attached to the distal end of the catheter body and is configured to be implanted beneath the patient's pericardial sac and above the surface of the myocardium covering the patient's left ventricle. An implantable port is attached to the proximal end of the catheter body and is configured to receive a cannula introduced percutaneously. The port is connected to supply drive gas received from the cannula to the pneumatic actuator via a gas chamber in the catheter body. By controlling the supply of drive gas to the implantable port, the pneumatic actuator can be driven at a desired rate controlled by the external drive unit.

[0034] In certain embodiments, an implantable cardiac assist catheter can include a distal tip having a guidewire lumen having an inlet port and an outlet port, wherein both ports are located distal to the pneumatic actuator. Such a "monorail" configuration is advantageous because it allows the remainder of the catheter body to have only a single fluid delivery lumen, thereby reducing the required diameter of the catheter. Thus, the gas lumen and the catheter body will typically be the only lumens present between the proximal end of the catheter body and the pneumatic actuator.

[0035] Optionally, the distal tip of the implantable cardiac assist catheter can also include an anchoring balloon or other anchoring structure. Such an anchoring structure can be deployed by advancing the distal catheter tip outward through the pericardium. After the pneumatic actuator is correctly positioned, typically above the patient's left ventricle, the anchor can be deployed (e.g., by inflating the balloon) to stabilize the catheter position for subsequent use.

[0036] In a fourth aspect, the present invention provides an external drive unit for an implantable cardiac assist catheter, such as the one just described. The external drive unit includes a pump assembly and a control circuit. The control circuit is typically configured to operate the pump assembly to actuate a pneumatic actuator on the implantable cardiac assist catheter in response to a patient's sensed heart rhythm.

[0037] In certain embodiments, the external drive unit may further include a connecting tube having a pump end attached to the pump assembly and a percutaneous port connection end, the percutaneous port connection end being configured to be removably attached to an implantable port, the implantable port being fluidically connected to a pneumatic actuator on the implantable cardiac assist catheter. In still other embodiments, the external drive unit may include an ECG circuit, wherein the ECG circuit is configured to receive signals from at least one ECG electrode located in any of the aforementioned locations, wherein at least one ECG electrode is implanted to detect the patient's heart rhythm. Typically, the connecting tube will include at least one conductor electrically coupled to the cannula and configured to connect the ECG electrode to the ECG circuit in the external drive unit.

[0038] In yet another exemplary embodiment, the control circuitry of the external drive unit can be configured to actuate the pneumatic actuator in synchronization with the patient's heart rhythm as measured by the ECG electrodes. As described above, actuation can be achieved by detecting the occurrence of an R-wave peak. The control circuitry can also be configured to detect an abnormal heart rhythm and further halt or modify actuation of the pneumatic actuator in any of the manners previously described. The pump assembly can also have any of the configurations previously described with respect to the heart assist system of the present invention.

[0039] For a fuller understanding of the nature and advantages of the present invention, reference should be made to the ensuing detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to better understand the invention and to see how it may be put into practice, some preferred embodiments are now described, by way of non-limiting examples only, with reference to the accompanying drawings in which like reference numerals indicate corresponding features in similar embodiments throughout.

[0041] Figure 1 is a perspective view of a heart assist system configured in accordance with the principles of the present invention.

[0042] Figures 2A to 2D Different configurations of pump assemblies suitable for use in the heart assist system of the present invention are shown.

[0043] Figures 3A to 3B A first implantable port configuration configured in accordance with the principles of the present invention is depicted.

[0044] Figures 4A to 4B A second implantable port embodiment configured in accordance with the principles of the present invention is depicted.

[0045] Figures 5A to 5B A third implantable port configuration configured in accordance with the principles of the present invention is depicted.

[0046] Figure 6Details are shown of how a needle or other cannula engages the wires of a conductive mesh embedded in the septum of an implantable port.

[0047] Figure 7A A needle cannula is depicted having a retaining bulb along its length.

[0048] Figure 7B A needle or other cannula according to the present invention is shown having retention barbs along its length.

[0049] Figures 8A to 8B An alternative access cannula configured in accordance with the principles of the present invention and having a fiber optic component for conveying cardiac rhythm information from an implantable port to an external drive unit is depicted.

[0050] Figure 9 Draws the applicable Figure 8A and Figure 8B An implantable port for an access cannula.

[0051] Figure 10A An alternative embodiment of a cardiac assist catheter having a balloon anchor at its distal tip is depicted.

[0052] Figure 10B Depicts the implanted Figure 1 heart assist system.

[0053] Figure 11 is a logic flow diagram illustrating the operation of the external drive unit of the heart assist system of the present invention. DETAILED DESCRIPTION

[0054] In the following description, various embodiments of the present invention will be described. For illustrative purposes, specific configurations and details are set forth to provide a thorough understanding of the embodiments. However, it will be readily apparent to those skilled in the art that the present invention may be practiced without these specific details. Furthermore, well-known features may be omitted or simplified to avoid obscuring the described embodiments.

[0055] Now refer to Figure 1 , a cardiac assist system 10 configured according to the principles of the present invention may include a cardiac assist catheter 12 and an external drive unit 14. The cardiac assist catheter 12 typically includes a catheter body 18 having a balloon 20 or other pneumatic actuator located at its distal end. An implantable port 24 is connected to the proximal end of the catheter body 18, and the body typically has a distal tip 26 having a short "single track" guidewire lumen defined between a guidewire lumen inlet port 28 and a guidewire lumen outlet port 30. The length of the guidewire lumen is typically 0.5 cm to 3 cm, typically 1 cm to 2 cm.

[0056] The port 24 includes a port body 38 or other housing having an opening on its upper surface. The opening is typically covered by a septum 40 that is penetrable by a needle.

[0057] The external drive unit 14 includes a needle 44 or other cannula attached to the distal end of a connecting tube 46. The connecting tube is attached to a pump 52 within a console 48, and the console also contains control circuitry 54 for controlling the pump and other operations of the heart assist system 10. Optionally, the external drive unit 14 may also include an ECG pad 56 connected to the control circuitry 54 by a connecting cable 58. Typically, the pump, control circuitry, and all other active components will be battery operated, and the external drive unit 14 will contain a replaceable and / or rechargeable battery.

[0058] Now refer to Figures 2A to 2D The pump assembly 52 may include a variety of configurations. For example, Figure 2A As shown in FIG, pump unit 52A, typically a diaphragm-type pump, is connected to cannula 44 via a series of valves 60a-60d. Pump 50A is configured to operate in a single direction at all times, meaning the inlet always receives gas and the outlet always delivers gas. To deliver gas to cannula 44, valve 60a is opened, allowing ambient air to flow to pump 50A. Ambient air is delivered from the pump outlet to open valve 60b. When gas is delivered to the cannula, valves 60c and 60d are closed. Gas continues to be delivered until pneumatic actuator 20 is charged, at which point valves 60a-60d are reversed. That is, gas inlet valve 60a is closed and return bypass valve 60c is opened, allowing gas to be drawn through cannula 44 and delivered by pump 52A through open exhaust valve 60d. By reversing the open / closed states of valves 60a-60d, the pump can first deliver gas through the cannula and then extract it, without reversing the operation of pump 52A.

[0059] Likewise Figure 2A As shown in FIG, an ECG lead 70 may be disposed between the cannula 44 and the control circuit 54 of the external drive unit 14.

[0060] Now refer to Figure 2D , a single pump 52B can be used with a pair of cannulas 44a and 44b. Valves 62a-62d will be used to reverse the gas flow between the cannulas. In particular, by opening valves 62a and 62d, ambient air can be delivered to gas delivery cannula 44a. By then closing valves 62a and 62b, and opening valves 62c and 62d, gas can be drawn through cannula 44b and out of exhaust valve 62d. The inflow and outflow of gas can be controlled by a method similar to Figure 2A The valve mode reverses the valve state to cycle.

[0061] exist Figure 2BIn FIG. 4 , each cannula 44 a and 44 b has a separate ECG lead 72 a and 72 b that is connected to the control circuit 54 of the external drive unit 14 .

[0062] Now refer to Figure 2C , a pump assembly 52 including two pumps 52c1 and 52c2 will be described. The control circuit 54 actuates the first pump 52c1 to deliver ambient air through valve 64a and then through the cannula 44, while the return valve 64b remains closed. After the pneumatic actuator is fully inflated or otherwise actuated, valve 64a will be closed and the pump typically stopped. As illustrated, the return valve 64b will then be opened and the pump 52c2 will be actuated to exhaust gas through the cannula 44 and out through the exhaust line. The operation of the two pumps and valves can be periodically reversed to cycle the delivery and exhaust of gas to and from the implant port at a desired rate.

[0063] Likewise Figure 2C As shown in FIG, an ECG lead 74 may be disposed between the cannula 44 and the control circuit 54 of the external drive unit 14.

[0064] Now refer to Figure 2D Next, a fourth pump assembly configuration will be described. This assembly includes two pumps 52d1 and 52d2. Each pump is in turn connected to a single cannula 44a and 44b, respectively. Although valves are typically provided, in theory, no valves are required to cycle the system between gas delivery via pump 52d1 and cannula 44a and gas extraction via cannula 44b and pump 52d2. This can be achieved by simply starting and stopping the pumps at alternating times during the cycle.

[0065] Likewise Figure 2D As shown in FIG, each cannula 44a and 44b is connected to the control circuit 54 via an ECG lead 76a and 76b, respectively.

[0066] Now refer to Figure 3A and Figure 3B , depicting a first implantable port embodiment 24a. Figure 3Ais a top view of the port, with the top surface typically oriented "forward" toward the patient's skin after implantation. A ring electrode 80 is attached to the outer circumference of the implantable port 24a and can optionally serve as an ECG electrode. A circumferential band of metal mesh 82 can be positioned above the outer circumference of the upper surface of the port, typically above a needle-penetrable septum 84. A second, smaller inner ring electrode 86 can also be positioned on the upper surface of the septum. The outer mesh electrode 82 is electrically insulated from the inner electrode 86 by a non-conductive septum material. Thus, a first metal sleeve and a second metal sleeve can be introduced through the inner and outer electrodes to provide separate connections for dual-lead EKG signal detection. The ECG electrodes themselves can be located on the body of the port 44a or elsewhere in the implantable system. Internal conductive wiring will be provided between the ECG electrodes and the mesh electrodes 82 and 86.

[0067] Now refer to Figure 4A and Figure 4B , depicts an alternative implantable port 24b having a first arcuate mesh electrode 90a and a second arcuate mesh electrode 90b formed on the upper surface of a needle-penetrable septum 92. Figure 4B As shown in FIG, the first electrode 94a can be positioned on the periphery of the port body, with the interior connected to one of the two arcuate mesh electrodes. The second electrode ( Figure 4B ) are located on the opposite face of the port body and can be connected to another of the arcuate mesh electrodes to provide a separate cannula connection for each of the ECG electrodes.

[0068] Figure 5A and Figure 5B Another implantable port assembly 95 is shown. The port assembly 95 includes a first port 24b that can be connected to the previously referenced Figure 4A and Figure 4B The second port 24c may have a single mesh electrode covering the entire surface of the underlying needle-penetrable septum. The mesh electrode 96 may be connected to any ECG electrode, typically to a conductive portion of the port body. Ports 24b and 24c are connected together by conduit portions 18a and 18b, and through a y-connector 100 to a common conduit body 18, which may be connected to a pneumatic actuator, as previously described. Figure 1 described.

[0069] Figure 6The diagram illustrates how the cannula 14 forms an electrical connection with the wires of the mesh electrode. Specifically, the mesh electrode comprises orthogonally arranged wires 102a and 102b. Where wires 102a and 102b intersect, small square cells are formed. The cells are sized smaller than the diameter of the cannula so that, when inserted through the wire mesh, the wall of the cannula 14 will inevitably contact all four wires defining a single cell. This ensures good electrical contact.

[0070] Now refer to Figure 7A The cannula can be modified to enhance retention when inserted through the septum of an implantable port, particularly through a wire mesh electrode structure on such a septum. Figure 7A As shown in , the needle structure 106 may have a series of bulbs 108 that help prevent the needle from being accidentally withdrawn from the mesh. Figure 7B As shown in FIG, the needle 110 may have a series of barbs 112 that prevent needle removal.

[0071] Now refer to Figure 8A 、 Figure 8B and Figure 9 , an optical system for transmitting ECG information from an implantable port to an external drive unit will be described. Figure 8A As shown in FIG, the needle assembly 120 includes a needle 122 having a plurality of optical fibers 126 axially embedded in a sheath 128. Figure 8B As shown in FIG, the optical fiber 126 is exposed in the distal surface of the sheath 128. Figure 9 , the implantable port 130 can be modified to receive the needle assembly 120 in a manner that transmits optical information to the optical fiber 126. Specifically, the needle assembly 120 can be inserted through the septum 132 of the port. The outer surface of the sheath 128 engages the wire embedded in the niche in the septum 132. The distal surface of the sheath 128 engages the upper surface of the circuit board 140. The circuit board 140 includes a plurality of optical emitters (not shown) that are configured to transmit light to the optical fiber 126 of the needle assembly 120. The needle 122 will pass through a hole or aperture 142 in the circuit board to allow the surface of the sheath to engage the circuit board. A funnel 144 is provided to assist in properly aligning the needle with the hole. ECG electrodes 146a and 146b on the outside of the port 130 are connected to the circuit board 140. Circuitry on the circuit board extracts ECG information from the electrodes and converts the information into light energy, which is transmitted by the optical emitters to the optical fiber 126. The light is transmitted via optical fiber to an external driver unit where it is converted back into electronic information suitable for use in the control system, as previously described.

[0072] Now refer to Figure 10B , as shown, Figure 1The heart assist system 10 can be implanted in a patient. Specifically, a balloon or other pneumatic actuator 20 is introduced into the pericardial sac between the inner surface of the pericardium P and the outer surface of the myocardium M. The pneumatic actuator 20 will preferably be positioned generally above the left ventricle so that inflation or other actuation of the actuator compresses the left ventricle, as Figure 10B 1. The port 24 is connected to the balloon via the catheter body 18 and is accessed percutaneously via the cannula 14. An external drive unit 48 delivers actuating gas to the port 24 via the connecting tube 46 and the cannula 14 to actuate (typically by inflating and deflating) the pneumatic actuator. The ECG is measured by an ECG pad 56, which is connected to the external drive unit via a cable 58. Optionally, other ECG signals may be measured by electrodes on the implantable port 24 or elsewhere in the system.

[0073] Now refer to Figure 11 , an exemplary protocol for operating the pneumatic actuator of the present invention will be described. The patient's ECG is measured using any of the ECG electrodes described above. The ECG measurement circuit is typically integrated into an external drive unit and operates according to well-known ECG measurement principles. The raw ECG signal undergoes processing, typically digital processing to remove motion artifacts from the signal, and the processed signal is then scanned to determine (typically by measuring R-peaks) the presence of signal artifacts associated with the patient's heart rhythm.

[0074] Although the R-peak value can be used to directly drive pump assemblies and pneumatic actuators, the R-peak pattern is typically evaluated to determine whether it is normal or abnormal. For example, the occurrence of consecutive single peak R values ​​can be compared to determine whether their length increases or decreases. If the RR peak interval remains constant within ±10% of the previous interval, the heart rhythm will be considered normal and a trigger may be generated. Typically, a second abnormality test will be applied to the RR interval over a cumulative number of beats (e.g., 10 beats). If the RR interval is greater than a threshold amount (e.g., 10%) of the average RR interval of the previous 10 beats, the heart rhythm is considered abnormal.

[0075] In the event of an abnormal heart rhythm being detected, the system can take any of a variety of actions. For example, the system can shut down the activation of the pneumatic actuator until the patient's natural heart rhythm returns to normal. Alternatively, in the event of a rapid heartbeat, the 1:1 synchronization between the natural heart rhythm and the activation of the pneumatic actuator can be altered, such that the actuator is activated every second natural beat (a 2:1 ratio), every third beat (a 3:1 ratio), and so on. Once the heart rhythm returns to normal, the pneumatic actuator can be reactivated at a 1:1 ratio.

[0076] Although specific embodiments of the present invention have been described in detail above, it will be understood that the descriptions described are for illustrative purposes only and that the above description of the present invention is not exhaustive. Specific features of the present invention are shown in some drawings and not in other drawings for convenience only, and any feature may be combined with another feature in accordance with the present invention. Many variations and substitutions are readily apparent to those skilled in the art. Such substitutions and variations are intended to be included within the scope of the claims. The specific features presented in the dependent claims may be combined and fall within the scope of the present invention. The present invention also encompasses embodiments as if the dependent claims were written in a multiple dependent claim format with reference to other independent claims.

[0077] Unless otherwise specified herein or clearly contradicted by the context, the use of the terms "a" and "an" and "said" and similar referents in the context of describing the present invention (particularly in the context of the appended claims) should be interpreted as covering both the singular and the plural. Unless otherwise specified, the terms "include", "have", "include" and "contain" should be interpreted as open terms (i.e., meaning "including but not limited to"). The term "attached" should be interpreted as partially or completely contained within, attached together or joined together, even if something intervenes. Unless otherwise specified herein, the description of the numerical range herein is only intended to be used as a shorthand method of individually referring to each individual numerical value falling within the range, and each individual numerical value is incorporated into the specification as if it were individually described herein. Unless otherwise specified herein or clearly contradicted by the context, all methods described herein can be performed in any suitable order. Unless otherwise stated, the use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the embodiments of the present invention, rather than to limit the scope of the present invention. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0078] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

Claims

1. A heart assist system comprising: a pneumatic actuator positioned proximate the distal end of the catheter and configured to be implanted beneath the patient's pericardial sac and above a myocardial surface overlying the patient's left ventricle; an anchor disposed distal to the pneumatic actuator to stabilize the pneumatic actuator at a desired position within the pericardial sac; an implantable port connected to the catheter near a proximal end of the catheter and configured to receive a percutaneously introduced cannula, wherein the port is connected to supply drive gas received from the cannula to the pneumatic actuator; An external drive unit, comprising: (a) a pump assembly; and (b) a control circuit configured to operate the pump to actuate the pneumatic actuator in response to a sensed heart rhythm of the patient; and A connecting tube has a pump end connectable to the pump assembly and a cannula end attached to the cannula.

2. The heart assist system of claim 1, wherein the pneumatic actuator comprises an inflatable balloon.

3. The heart assist system of claim 1 , wherein the pneumatic actuator comprises a piston.

4. The heart assist system of claim 1, wherein the implantable port comprises a needle-penetrable septum and the cannula comprises a needle configured to percutaneously penetrate the septum.

5. A heart assist system according to claim 4, wherein the septum has an area large enough to provide multiple sites for needle penetration.

6. The heart assist system of claim 1 wherein the implantable port comprises a mechanical valve for receiving the cannula.

7. The heart assist system of claim 1 further comprising at least one ECG electrode positioned and configured to detect the patient's heart rhythm.

8. The heart assist system of claim 7, wherein the at least one ECG electrode comprises at least a portion of the cannula.

9. The heart assist system of claim 7, wherein the at least one ECG electrode is located on the implantable port.

10. The heart assist system of claim 7, wherein the at least one ECG electrode is located on the connecting tube.

11. The heart assist system of claim 7, wherein the at least one ECG electrode is located on the pneumatic actuator.

12. The heart assist system of claim 7, further comprising an ECG circuit in the external drive unit.

13. The heart assist system of claim 12, wherein the at least one ECG electrode is connected to the ECG circuit via a conductor disposed through the connecting tube.

14. The heart assist system of claim 12, wherein the at least one ECG electrode is configured to be externally attached to the patient and connected to the ECG circuit via an external lead.

15. The heart assist system of claim 12, wherein the control circuit is configured to actuate the pneumatic actuator in synchronization with the patient's heart rhythm measured by the ECG.

16. The heart assist system of claim 15, wherein the control circuit is configured to actuate the pneumatic actuator when an R-wave peak occurs.

17. The heart assist system of claim 15, wherein the control circuit is further configured to detect an abnormal heart rhythm.

18. The heart assist system of claim 17, wherein the control circuit compares the time between consecutive R-peaks and determines the abnormal heart rhythm to be abnormal if the time increases or decreases by more than a predetermined threshold percentage.

19. The heart assist system of claim 17 wherein the control circuit compares the time between consecutive cumulative R-peaks and determines the abnormal heart rhythm to be abnormal if the total variability exceeds a predetermined threshold percentage.

20. The heart assist system of claim 17, wherein the control circuit is further configured to stop actuation of the pneumatic actuator when an abnormal heart rhythm is detected.

21. The heart assist system of claim 17, wherein the control circuit is further configured to actuate the pneumatic actuator at a predetermined rate that is asynchronous with the heart rhythm when an abnormal heart rhythm is detected.

22. The heart assist system of claim 17, wherein the control circuit is further configured to actuate the pneumatic actuator at a rate that is modified proportionally with respect to the patient's heart rhythm when an abnormal heart rhythm is detected.

23. The heart assist system of claim 22, wherein the control circuit is further configured to actuate the pneumatic actuator at a reduced rate relative to the patient's heart rhythm when tachycardia is detected.

24. The heart assist system of claim 1, wherein the pump assembly is configured to alternately deliver the drive gas to and withdraw the drive gas from the pneumatic actuator.

25. A heart assist system according to claim 24, wherein the pump assembly includes a pump connected to a valve, wherein the pump is configured to flow the driving gas in one direction and the valve is configured to alternately deliver the driving gas to the pneumatic actuator and withdraw the driving gas from the pneumatic actuator.

26. The heart assist system of claim 24, wherein the pump assembly comprises a first pump that delivers drive gas to the pneumatic actuator and a second pump that removes drive gas from the pneumatic actuator.

27. The heart assist system of claim 1 wherein the anchor comprises a balloon.

28. A device for assisting cardiac function in a patient suffering from heart failure, the device comprising: one or more electrodes configured to detect an ECG of the patient to determine a heart rhythm; a cannula configured to percutaneously access the implant port; a pneumatic actuator implanted beneath the patient's pericardial sac and above a myocardial surface overlying the patient's left ventricle and connected to the implant port, wherein the pneumatic actuator is configured to receive a drive gas delivered to the implant port through the cannula; as well as an anchor disposed distal to the pneumatic actuator to stabilize the pneumatic actuator at a desired position within the pericardial sac; wherein the drive gas delivery is synchronized with the determined heart rhythm such that the pneumatic actuator compresses the heart at a rate that matches the heart rhythm.

29. The apparatus of claim 28, wherein the pneumatic actuator is implanted below the patient's pericardial sac and above the myocardial surface.

30. The apparatus of claim 28, wherein the ECG is detected using one or more electrodes located on the implanted pneumatic port.

31. The apparatus of claim 28, wherein the ECG is detected using one or more electrodes located on the implanted pneumatic actuator.

32. The apparatus of claim 28, wherein the ECG is detected with the cannula acting as an ECG electrode.

33. The device of claim 28, wherein the ECG is detected using external electrodes.

34. The device of claim 28, wherein the one or more electrodes are further configured to detect an abnormal heart rhythm.

35. The apparatus of claim 34, wherein delivery of the drive gas is stopped when an abnormal heart rhythm is detected.

36. The apparatus of claim 34, wherein the rate at which the drive gas is delivered is altered when an abnormal heart rhythm is detected.

37. The apparatus of claim 36, wherein the rate is lower than the rate of the detected heart rhythm.

38. The apparatus of claim 37, wherein the rate is a predetermined fixed rate.

39. The apparatus of claim 28, wherein the cannula is configured to be removed from the access site when infection at the access site is observed.

40. The apparatus of claim 39, wherein the cannula is configured to be replaced after treating the infection.

41. The device of claim 40, wherein the cannula is replaced through a different site to access the port.

42. The device of claim 41, wherein the cannula comprises a needle and the port comprises a penetrable septum penetrable by the needle, and the different locations are different areas on the septum.

43. The device of claim 28, wherein the anchor comprises a balloon.

44. An implantable cardiac assist catheter for use with an external drive unit, the implantable cardiac assist catheter comprising: a catheter body having a proximal end and a distal end; a pneumatic actuator located at the distal end of the catheter body and configured to be implanted beneath the patient's pericardial sac and above a myocardial surface overlying the patient's left ventricle; an anchor disposed distal to the pneumatic actuator to stabilize the pneumatic actuator at a desired position within the pericardial sac; as well as An implantable port is located at the proximal end of the catheter and is configured to receive a percutaneously introduced cannula, the port being connected to supply drive gas received from the cannula to the pneumatic actuator through a gas lumen in the catheter body.

45. An implantable cardiac assist catheter according to claim 44, wherein the catheter body includes a distal tip having a guidewire lumen, the guidewire lumen having an inlet port and an outlet port, both of which are located distal to the pneumatic actuator.

46. ​​An implantable cardiac assist catheter according to claim 45, wherein the gas lumen is the only lumen in the catheter body between the proximal end and the pneumatic actuator.

47. An implantable cardiac assist catheter according to claim 44, wherein the anchor comprises a balloon.

48. An external drive unit for use with the implantable cardiac assist catheter of claim 44, the external drive unit comprising: (a) Pump assembly; as well as (b) a control circuit configured to operate the pump assembly to actuate the pneumatic actuator on the implantable cardiac assist catheter in response to the patient's sensed heart rhythm.

49. The external drive unit according to claim 48 further includes a connecting tube, wherein the connecting tube has a pump end and a percutaneous port connection end, wherein the pump end is attached to the pump assembly, and the percutaneous port connection end is configured to be removably attached to an implantable port, and the implantable port is fluidically connected to the pneumatic actuator on the implantable cardiac assist catheter.

50. The external drive unit of claim 49, further comprising an ECG circuit in the external drive unit, wherein the ECG circuit is configured to receive signals from at least one ECG electrode, wherein the at least one ECG electrode is positioned and configured to detect a heart rhythm of the patient.

51. The external drive unit of claim 50, wherein the connecting tube comprises at least one conductor configured to be removably connected to the implantable port, the implantable port being electrically coupled to one or more ECG electrodes.

52. The external drive unit of claim 48, wherein the control circuit is configured to actuate the pneumatic actuator in synchronization with the patient's heart rhythm as measured by ECG electrodes.

53. The external drive unit of claim 52, wherein the control circuit is configured to actuate the pneumatic actuator when an R-wave peak occurs.

54. The external drive unit of claim 52, wherein the control circuit is further configured to detect an abnormal heart rhythm.

55. The external drive unit of claim 54, wherein the control circuit is further configured to cease actuation of the pneumatic actuator when an abnormal heart rhythm is detected.

56. The external drive unit of claim 55, wherein the control circuit is further configured to actuate the pneumatic actuator at a predetermined rate that is asynchronous with the heart rhythm when an abnormal heart rhythm is detected.

57. The external drive unit of claim 55, wherein the control circuit is further configured to actuate the pneumatic actuator at a rate that is modified proportionally with respect to the patient's heart rhythm when an abnormal heart rhythm is detected.

58. The external drive unit of claim 57, wherein the control circuit is further configured to actuate the pneumatic actuator at a reduced rate relative to the patient's heart rhythm when tachycardia is detected.

59. The external drive unit of claim 48, wherein the pump assembly is configured to alternately deliver the drive gas to the pneumatic actuator and withdraw the drive gas from the pneumatic actuator.

60. The external drive unit of claim 59, wherein the pump assembly comprises a pump coupled to a valve, wherein the pump is configured to flow the drive gas in one direction, and the valve is configured to alternately deliver the drive gas to and withdraw the drive gas from the pneumatic actuator.

61. The external drive unit of claim 59, wherein the pump assembly comprises a first pump that delivers drive gas to the pneumatic actuator and a second pump that removes drive gas from the pneumatic actuator.

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