Patent Application
20210046234
The present disclosure relates to systems for powering implanted medical devices such as ventricular assist devices.
Congestive heart failure is a disease that results from the inability of the heart to pump blood throughout the body at its normal pace, causing blood to flow a slower rate with increased pressure. As a result, the heart is unable to meet the oxygen and nutrient demands of an individual's vital organs. Heart failure may be caused by cardiomyopathy, heart valves damage, coronary heart disease, hypertension, and, in some cases, diabetes. Worldwide, millions of patients currently suffer from congestive heart failure. While many are candidates for heart transplantation, others can be helped with electro-mechanical heart implants, such as a ventricular assist device (VAD), which is an implantable electro-mechanical pump that serves to improve or replace the function of a failing heart.
VADs require a power source to operate the pump. In a traditional arrangement, the VAD is connected to an external power source by a transcutaneous wire. The exit site of the wire is typically in the patient's abdomen. As with any medical device that requires a transcutaneous wire, the exit site is often vulnerable to infection.
Wireless configurations alleviate the infection problem and are less cumbersome than transcutaneous wires, providing the patient with increased mobility and quality of life. One wireless approach is transcutaneous energy transfer (TET), wherein an external energy source is directed toward an implanted energy harvesting device in an arrangement that seeks to minimize radiofrequency (RF) exposure of the patient. Typically the receiver coil is located just under the patient's skin and the transmitter is located just above the skin. Such TET systems are very sensitive to misalignment and movement of the implanted coil. Another drawback of TET systems is that the electromagnetic field density is so high that it can cause heating of the skin and even burns. An alternative to TET is coplanar energy transfer (CET). CET systems include an implanted receiver coil that receives wireless power from transmitter coil external to the body. The transmitter coil completely surrounds the part of the patient's body wherein the receiver coil is implanted. Unlike in TET, the RF energy that is inductively transmitted into the patient's body from the transmitter coil is spread out and not concentrated or focused on a particular area, reducing the risk of heating and burns. And since the transmitter and receiver merely need to be in the same plane, rather than precisely aligned, CET systems do not suffer from the misplacement problems of TET systems.
Although wireless systems reduce the incidence of infection and increase mobility for the patient, they introduce additional safety risks resulting from the lack of a hardwire connection to the power source. If the wireless connection suddenly fails and the implanted device cannot receive power, a patient's life may be at risk if he cannot quickly get help.
The present disclosure provides systems for powering and controlling implanted medical devices such as VADs, in a configuration that allows a user to switch between wireless and hardwired connections. These hybrid systems combine the convenience of wireless electromagnetic power transfer with the safety of hardwired power transfer. Embodiments of the disclosed systems include redundancy for the wireless power source, the implanted controller, or both.
The system generally involves a VAD connected to an implantable controller that operates the motor in the VAD, and an implantable power receiver that provides power to the controller and the VAD. The power receiver is configured to wirelessly receive electromagnetic power from a power transmitter that can be located outside the body such that it can deliver power to the power receiver implanted within the body. The external power transmitter is electrically connected to a power source, such as a battery, and may also be connected to an external controller that regulates the power transfer. In addition to the wireless power transfer components, the system also includes a connector device, which is electrically connected to the other implanted components and is configured to be percutaneously implanted in the patient. The connector device may take the form of a socket or an outlet configured to accept a plug that is hardwired to an external power source, which may be the same power source as the wireless transmitter or may be a different power source altogether. When the external power source is plugged into the connector, it completes a circuit from the external power to the VAD, thereby allowing the VAD to be powered by the external power source. There may also be an external controller associated with the plug, which may be the same as the external controller associated with the wireless power transfer or may be a different controller. When connected, the external controller can send a signal to the implanted controller to cause the implanted controller to stop operating the VAD, and the external controller can then take over control of the VAD.
The system therefore includes the components for wireless power transfer (either TET or CET), as well as a backup hardwired power source and/or controller that can transmit power through a wire to the VAD via the percutaneously implanted connector. The percutaneously implanted connector can be used as a backup power source when the wireless power transfer fails, or it can simply be an alternative power source that the patient can selectively use, such as for overnight charging. The hybrid system provides the user with the freedom to decide if and when an implanted medical device receives power wirelessly or through a hardwired connection.
Aspects of the disclosure relate to a system for treating a heart condition in a patient, the system including a VAD, a controller, and a power receiver each configured to be implanted within the body and electrically associated with one another. The implanted power receiver is further configured to wirelessly receive electromagnetic power from a power transmitter disposed external to the patient's body. The system also includes a connector device configured to be implanted percutaneously in the body and hardwired to the controller. The connector device can be hardwired to a power source external to the patient to provide redundancy for the implanted power receiver.
In embodiments, the implanted controller includes a rechargeable battery configured to be charged by one or both of the implanted power receiver and the external power source.
In some embodiments, the system also includes an external monitoring device configured to communicate with the implanted controller wirelessly, such as via a radio frequency in the communication spectrum for medical implants (MICS). The external monitoring device may receive data from the implanted controller indicating the operational status of the VAD. The data may include an alert that the VAD is not receiving power from the implanted power receiver. The data may be shown on a display associated with the external monitoring device.
The connection device may be configured to be implanted percutaneously in any part of the patient's body. In some embodiments, it is configured to be disposed behind the patient's ear. The connection device may include a socket configured to accept a plug that is hardwired to the external power source.
In a related aspect of the invention, a system for treating a heart condition in a patient includes a connector device configured to be implanted percutaneously and hardwired to the VAD. The connector device is configured to be hardwired to a controller external to the patient. The external controller is configured to determine whether the implanted controller is driving the VAD and to provide redundancy for the implanted controller only when the implanted controller is not driving the VAD.
The external controller can be associated with an external power source. The external controller can be configured to communicate a signal to the implanted controller to cause the implanted controller to stop driving the VAD. The signal can be transmitted wirelessly or via a communication line that runs through the power lines that connect the controllers to the VAD. The signal can be sent automatically in response to the external controller being plugged in to the connector device.
The disclosed powering system for implanted medical devices such as a ventricular assist device (VAD) includes the components for wireless power transfer (either TET or CET), as well as a hardwired power source and/or controller that can transmit power through a wire to the VAD via the percutaneously implanted connector. The disclosed system is built from components of traditional VAD systems and combines them in new ways to produce unexpected advantages. In particular, the hardwired power source can be used as an emergency backup power source in case the wireless power transfer fails, or it can be used for charging at any other convenient time for the patient, such as overnight charging. The disclosed systems also include wireless monitoring devices that can allow the user to remove any external charging apparatus and be free and unencumbered except for the monitoring device, which may be a wristwatch. The versatility of the disclosed systems gives the patient several options for how best to charge an implanted medical device, based on the particular needs and lifestyle of the patient, and also provides redundancy for implanted wireless power receivers and controllers.
Although the invention is useful for any implanted medical device, it will be described with reference to a VAD in particular. A VAD is an electro-mechanical device that partially or completely replaces the function of a failing heart. Some VADs are intended for short term use, typically for patients recovering from heart attacks or heart surgery, while others are intended for long term use (months to years and in some cases for life), typically for patients suffering from CHF. Unlike artificial hearts, VADs do not require the removal of the patient's heart. VADs are designed to assist either the right (RVAD) or left (LVAD) ventricle. The choice of device depends on the underlying heart disease and the pulmonary arterial resistance which determines the load on the right ventricle. LVADs are most commonly used but when pulmonary arterial resistance is high, right ventricular assist becomes necessary. Long term VADs are normally used to keep patients alive with a good quality of life while they wait for a heart transplant. Many types of VADs are compatible with the presently disclosed powering system. First generation VADs, like the one described in U.S. Pat. No. 4,906,229, emulate the heart by using a pulsatile action where blood is alternately sucked into the pump from the left ventricle then forced out into the aorta. These devices are usually cumbersome and necessitate major surgery for their implantation into the vascular system and for introducing the cannula into the heart ventricle. More recent devices are based on intravascular continuous flow pumps, which can be roughly categorized as either centrifugal pumps, as described in US 2004/0143151, or axial flow impeller driven pumps, as described in U.S. Pat. No. 4,957,504. These second generation VADs have impellers with high flow rate capability and are much smaller than the first generation VADs, but have contacting bearings that suspend the rigid motor. The bearing contacts generally cause undesirable clot formation either inside or around the periphery of the bearings, making these devices unsuitable for long-term use. In these pumps, blood experiences traumatization and damage due to shearing and vortexing into the small gaps between the outer edge of the stator blades and the inner side of the pipe carrying blood. Newer VADs overcome these issues by suspending the impeller in the pump using either hydrodynamic or electromagnetic suspension, thereby decreasing risks of thrombosis or hemolysis. Such pumps are described for example in U.S. Pat. Nos. 6,527,699 and 7,467,929.
The invention provides hardwired redundancy to a wireless VAD system. Generally a VAD system has a controller that includes or is connected to a rechargeable battery. The battery can be charged by a power source, such as a wireless receiver or a hardwired power connection. A completely wireless system (i.e., where the internal controller is wirelessly powered and has no backup wired connection) would be problematic because if any of the wireless powering components were to fail, there is no easy way to connect a hardwired connection. It is therefore preferable for wireless systems to have redundancy for the implanted components. For example, if the connection between the wireless receiver and the controller fails, a redundant power source could be provided for charging the battery. However, if the controller itself fails, then merely having a backup input power source to the controller does not solve the problem Likewise, if the connection between the controller and the VAD fails, it is important to have a redundancy for the control of the VAD. For traditional VAD systems with external controllers, the simple solution is to just replace the controller by plugging in a new one. But for implanted controllers, redundancy is more complicated because the implanted controller cannot be readily unplugged from the VAD when a backup controller is activated, and connecting two controllers to the VAD simultaneously would cause a short or an explosion. The invention involves systems for providing redundancy to the wireless power source and/or to the controller, which will be described in greater detail below.
Another benefit of the present disclosure is the inclusion of wireless power, an example of which is shown in
Coplanar energy transfer (CET) systems solve this problem. The CET system shown in
The transmission belt 345 includes a transmitter coil, and transmits power to the internal receiver coil 331 via a magnetic coupling. It is noted that a power source such as battery 313 must be associated with the external transmitter coil to provide that coil with the power that it will then wirelessly transmit for receipt by the implanted receiver coil 331. An external controller 319 regulates the operation of the transmitter coil Like the transmitter coil, both the power source and the controller will be external to the patient. The external source can be an AC current source, and the transmitter coil can be electrically connected to the AC current source. It also is noted that the transmitter coil can be a transceiver—that is, capable of both transmitting and receiving. The external controller can run power transmission algorithms, communicate with the implant (e.g. through the frequency band of the Medical Implant Communication Service (MICS), which includes frequencies between 402 and 405 MHz), and push power to the belt from the battery 313. The external battery 313 is able to provide power to the transmission, and allow for generation of the electromagnetic field. Although
Wireless systems such as TET and CET are beneficial because they are less physically restrictive than wired systems and obviate the need for a transcutaneous wire. However, they present a safety concern due to their inaccessibility in case of emergency. If there is a failure in one of the implanted devices that prevents power from reaching the VAD, or if there are wireless connectivity problems, the patient may be at risk.
The hybrid powering systems of the present disclosure address many of these shortcomings while providing additional versatility to the patient. A hybrid powering system for an implanted medical device includes components for wireless power transmission, as well as a hardwired connection that can be used either as an emergency backup or for regular charging, or both. Emergency hardwire connections are described in US 2013/0053624, incorporated by reference in its entirety. With systems of the present disclosure however, a patient has several options for how to use the hardwired connection. The patient may choose, for example, to power up an implanted rechargeable battery using the hardwired connection any time it is convenient to do so, and then being free of any external apparatus for several hours; or alternatively, the patient may rely on the wireless assembly for everyday use and only use the hardwired connection in the even the wireless fails. Or a patient may enjoy the freedom of wireless powering when outside the home, but prefer the wired connection for home use or overnight charging. In any event, having two powering options gives the user freedom of choice. Rather than sacrificing convenience for safety, or vice versa, the hybrid powering system allows the patient to choose which type of power to use on an as-needed basis. The system also provides redundancy for the wireless power receiver, the implanted controller, or both.
There are multiple ways to provide redundancy to the systems described herein. The two different embodiments shown in
In addition to the wireless power receiver 431, there is also a redundant external power source (not shown) that can be connected to the controller 409 by plugging in to the connector device 450 that leads to the controller 409 by wire 407. The connector device 450 generally takes the form of a socket that is configured to accept a plug (not shown) hardwired to a power source (also not shown) such as a battery or AC current source. The connector device 450 is configured to be implanted percutaneously in the patient with the socket oriented outward so that it is exposed external to the patient. The connector device 450 is thus electrically connected to the implanted VAD 401 while also being capable of receiving a plug from the external power source. The redundant power source is separate from the wireless power source. The two power sources can each have their own input connection to the controller, or they can be merged into a single wire, as is shown in
Due to its percutaneous placement, the connector device 450 can be used for fast bailout of the implanted power receiver if it fails. The hardwired connection via connector device 450 provides a backup source for charging the battery, thereby reducing a risk associated with wireless powering. This allows backup input power without requiring surgery. This bailout could be performed by the patient or by a caregiver or any other individual nearby. But while this second source of input power in the Type A configuration provides redundancy for the wireless receiver, it does not provide redundancy for the whole system.
That is why it may be desirable in some situations to instead implement the more complex system shown in
As with the Type A embodiment, in the Type B embodiment the wired connection occurs through the percutaneous connector. But with Type B, the connection provides controller redundancy as well as an external power source. This system is useful as a backup in the event that the internal controller fails, or simply to take over the operation of the VAD in emergency situations. The external controller may be separate from the external power source, or the two units may be coupled together as a single device.
In the Type B configuration shown in
In any embodiment the redundant external controller may include a three-phase power supply connected in parallel to the internal controller 409. The external controller can drive the VAD 401 when the internal controller 409 has failed.
The disclosure recognizes that having two controllers simultaneously connected to the VAD introduces a potential complication into the system. That is, if both controllers were simultaneously providing output power to the VAD, it would result in a short or explosion. Therefore, the present invention provides a process for switching from internal power to external power without resulting in a short. The backup controller is configured to engage in a particular sequence of steps when it is connected, to ensure that the implanted controller is deactivated before the external controller begins providing the output power.
When the backup external controller is connected, it first senses whether the internal controller 409 is functional. If the internal controller 409 has stopped, the backup begins powering the VAD 401 and providing control from the external controller. However, if the internal controller is still providing output power when the backup is plugged in, the external controller will not drive the VAD 401 until the internal controller 409 has stopped. It will therefore communicate a signal to the internal controller to stop it from continuing to drive the VAD. The signal between the external controller and internal controller can be transmitted wirelessly via RF link such as through the MICS frequency band, or there can be a communication line that runs through the power lines that connect the controllers to the VAD, so that the signal can be sent via a high frequency communication signal modulation through the connected wire. The external controller then continues to validate whether the internal controller has stopped. It may do this by periodically pinging the internal controller to verify whether it is still providing output power. Once the external controller has confirmed that the internal controller has stopped, the external controller begins driving the VAD by sending output power through the hardwired connection.
The Type B configuration has been described as the more complex means of backing up the VAD system, because it requires the above-mentioned communication solution to prevent a short in the VAD. However, the Type A configuration may be preferred in some situations where a simpler or more robust or cost-effective system is desired.
In some embodiments, the percutaneous connector device 450 is configured to be implanted behind the patient's ear. Using this region as the exit point for a percutaneous wire is considered to pose less risk of infection, compared with tunneling out of the abdomen as shown in
A preferred embodiment, however, is shown in
The hybrid power systems described herein can also include external communication devices for monitoring the function of the implanted VAD and power components. The external communication device can monitor various parameters of the implanted elements and alert the user to certain conditions, such as the need to recharge. Methods and systems for alerting a patient when an implanted battery is low are found in US 2015/0130283 and US 2018/0008760, which are incorporated herein by reference in their entirety. In some embodiments, the external communication device can take the form of a wristwatch or a tablet. An example of such a configuration is shown in
In some embodiments, the user control can be enhanced with the addition of a tablet, PC, or other device that can communicate with the wristwatch and/or directly with the implanted controller.
The connector device 751 can be a regular external connector, attached to the driveline, like a push-pull connector. Alternatively, the connector 751 can be anchored to the body. For example, the implanted connector can be anchored to bone (such as one or more ribs, or the sternum), or it can be anchored to another anchoring hook. It is similar to Jarvik's behind-the-ear pedestal connector 750, but located in the abdominal area and allows for daily battery connect/disconnect for charging of the battery. The added value of the anchoring is that the connector 751 will have less movement when connected/disconnected, yet it is located in the abdominal area and thus is simple to implant.
An external battery 713 can be carried by the patient and is configured to be plugged into the connector device 750 or 751 to serve as an external power source to charge the controller 709 battery and to operate the VAD 701. A wristwatch 780 is configured to serve as a communication hub that can send and receive wireless signals to the implanted controller 709 via the MICS or MedRadio spectrum. The wristwatch 780 is configured to provide indicators of VAD performance, battery life, operational status, and alarms to alert the user to certain conditions. The wristwatch 780 may be similar to that described in published application US 2018/0126053, the contents of which are incorporated by reference. In addition to communicating with the implanted controller 709, the wristwatch 780 is configured to communicate with a tablet 790 or other similar device. The communication between the wristwatch 780 and the tablet 790 can use Bluetooth® or other similar wireless transmission modes. The tablet 790 can be a standard off-the-shelf tablet configurable to run an application for communicating with the wristwatch 780 using a common transmission mode. The tablet 790 can provide the same information and alerts as the wristwatch 780, as well as other usability features. For example, the patient, caregiver, or doctor can use the tablet 790 to monitor all of the relevant parameters of the implanted devices and change their configuration as needed.
As shown in
This application is a continuation-in-part of U.S. application Ser. No. 16/217,428, filed Dec. 12, 2018, which claims the benefit of and priority to U.S. Provisional Application Ser. No. 62/635,734, filed Feb. 27, 2018, and U.S. Provisional Application Ser. No. 62/597,570, filed Dec. 12, 2017, the contents of each of which are incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62635734 | Feb 2018 | US | |
| 62597570 | Dec 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16217428 | Dec 2018 | US |
| Child | 17068363 | US |
