A SYSTEM, AN APPARATUS AND A CONTAINER FOR STORING AN IMPLANTABLE MEDICAL DEVICE, AND A METHOD FOR PACKAGING SUCH A DEVICE

Technical Field The present invention relates to a system for improving the communication with an implantable medical device while being stored prior to implantation in body tissue. The present invention also relates to an apparatus comprising an implantable medical device and a container for storing the implantable medical device prior to implantation in body tissue. Further, the present invention relates to a container for storing an implantable medical device. Finally, the present invention relates to a method for packaging an implantable medical device prior to implantation in body tissue.

Background of the Invention

In the context of implantable medical devices, IMDs, it is common to pro- vide a communication link between the implanted IMD and an external device, such as a programmer or monitor, in order to allow for transmission of commands from the external device to the implanted IMD and to allow for transmission of stored information and/or sensed physiological parameters from the implanted IMD to the external device. Conventionally, communication between an implanted IMD and an external device has been accomplished by means of a telemetry system which includes a radio transmitter/receiver and one or more antennas included in the IMD and a radio transmitter/receiver and one or more antennas included in the external device. The IMD typically includes an antenna located either within the hermetic housing containing the circuitry, in a plastic header or connec- tor block used to interconnect the IMD to electrical leads. Telemetry is a technology that allows the remote measurement and reporting of information of interest to the system operator. In the context of IMDs, the IMD is arranged to measure and record data regarding the patient and to transmit these data to the programmer, typically via wireless communications using radio frequency systems. By means of telemetry the programmer can run tests, and program and operate the IMD at a distance from the patient.

In the past, the external device has been provided with a programming head containing an antenna, intended to be placed in close proximity to the im-

planted IMD. Today, telemetry systems for IMDs have been proposed, in which the communication occurs directly between the external device, e.g. the programmer or monitor, which may be located at a distance from the patient, and the implanted IMD. IMD telemetry systems are generally designed for maximum efficiency under implanted condition, i.e. the dielectric constant and conductivity of body tissue is taken into account when designing the telemetry and antenna system. Programming and interrogation operations, however, are not limited to occur when the IMD has been implanted. When the IMD is stored before the implant procedure and during the implant procedure, telemetry communication may be required for testing procedures or for verifying or customizing initial programmable parameter values before the IMD is implanted. However, since IMD telemetry systems are not designed for conditions where the IMD is located outside the implanted environment prior to implantation, the efficiency of the IMD telemetry systems prior to implantation is affected.

US 2006/0020300 A1 discloses a solution to this problem. A wireless communication system is described, comprising an IMD and a package antenna adapted for coupling to the IMD antenna when the IMD is outside the implanted environment. The package antenna extends the IMD antenna length prior to im- plantation in order to improve the efficiency of the telemetry link between the IMD and an external device, such as a programmer or monitor. The package antenna is provided on a pouch in which the IMD is placed, or is provided on the packaging tray assembly, e.g. placed within the packaging tray or on the tray lid. The package antenna is made of a conductive material and is in the form of a monopole, dipole, loop, microstrip patch, or slot antenna.

However, the use of a conductive material formed into an antenna, as suggested by US 2006/0020300 A1 , is somewhat complicated and thus connected with costs. The capacitive or direct electrical coupling between the packaging antenna and the IMD is a weak link, due to the risk of interruption of the coupling. US 2006/0224206 A1 discloses an IMD outfitted with an optional antenna assembly. However, this optional antenna assembly is optimized to suit the need of the particular IMD application under implanted conditions, e.g., in consideration of the age, sex, size, or condition of the patient, or implant orientation within the patient, and not under conditions prior to implantation.

US 2006/0197494 A1 describes a shipping container for storing an IMD prior to implantation. However, this shipping container is designed to allow charging of the IMD without disturbing the container, and not designed to increase the efficiency of the IMD telemetry system.

The Object of the Invention

The object of the present invention is thus to improve the telemetry communication between an external device and an implantable medical device stored prior to implantation, in a more efficient manner in relation to prior art.

Summary of the Invention The above-mentioned object is achieved by providing a system, apparatus and container as defined in the claims 1 , 7 and 21 , respectively. The above-mentioned object is also attained by providing a method as defined in claim 34.

For an efficient transfer of energy, the impedance of the radio/transceiver, of the antenna and of the transmission line connecting them must be the same. Transceivers and their transmission lines are typically designed for 50 ω impedance. If the antenna has an impedance different from 50 ω, then there is a mismatch and an impedance matching circuit is required. The input impedance of an antenna is generally a function of frequency. Thus, the antenna will be matched to the interconnected transmission line and other associated equipment, such as a radio frequency transmitter/receiver or transceiver, only within a bandwidth. In addition, the input impedance of the antenna depends on many factors including its geometry, its method of excitation, and its environment, such as its proximity to surrounding objects, e.g. metal or dielectric objects.

In order to match the antenna to the radio and the transmission line of an IMD, tuning using tunable reactive components is possible and widens the usable spectrum of antenna impedances. However, the great difference between the environment of body tissue, where the IMD is implanted, and the environment of a shipping container, where the IMP is stored prior to implantation, would necessitate a very big tuning capability to handle this load. Instead, the inventor of the present invention, has realized that a more viable way is to manipulate the input impedance of the antenna when the IMD is stored in the shipping container. By altering the electrical material properties of the storage means in the surroundings of the implantable medical device as suggested by the present invention, such that

the input impedance of the antenna is adjusted to improve receive and transmit properties of the antenna when the implantable medical device is stored by the storage means, an effective improvement of the telemetry communication between an external device and the IMD is attained. This solution is uncomplicated and in- expensive. Since this solution does not require a capacitive or direct electrical coupling between the IMD and any external equipment in order to improve the efficiency of the antenna, the risk of interruption of such a coupling is eliminated.

By the present invention as claimed in the enclosed claims, it is possible to efficiently communicate with the IMD while stored in a shipping container via radio frequency communication over larger distances. This enables a user to make an inventory of the IMDs in stock by means of an external radio frequency communication device, e.g., an inventory of the amount of IMDs, types of IMDs etc. By the present invention it is also possible for the user to execute testing procedures while the IMD is stored in the shipping container and while being in stock, or to verify or customize initial programmable parameter values before the IMD is implanted.

According to an advantageous embodiment of the system according to the present invention, the alteration means is arranged to set the electrical material properties of a region in proximity to the antenna of the implantable medical de- vice.

According to further advantageous embodiments of the system according to the present invention, the alteration means is arranged to set the dielectric constant of the region above 10, and further advantageously, to set the dielectric constant of the region between 10 and 60, preferably between 30 and 40. Advanta- geously, the alteration means is arranged to set the conductivity of the region.

According to another advantageous embodiment of the system according to the present invention, the alteration means is arranged to mechanically fixate the implantable medical device in its position within the storage means. Hereby, the alteration means provides a dual functionality. According yet another advantageous embodiment of the system according to the present invention, the alteration means comprises a member as disclosed hereinafter. Advantageously, the means for wireless communication comprises transmitter/receiver circuitry, and further advantageously, the storage means comprises a container as disclosed below.

The antenna of the IMD can be located in the housing of the IMD containing the device circuitry, in or on the plastic header of the IMD used to interconnect the IMD to electrical leads, mounted to the IMD housing, or incorporated as a por- tion of one of the leads. According to an advantageous embodiment of the apparatus according to the present invention, the member is positioned in the close surroundings of the antenna of the IMD, which efficiently influences the input impedance of the antenna more, and advantageously, the member extends along a substantial portion of the length of the antenna, which provides an even more effective influence on the input impedance of the antenna. The member can abut the IMD or be position with a small distance to the IMD. Advantageously, the member should not enclose too much of the antenna in order to avoid attenuation of the electromagnetic waves to and from the antenna.

Advantageously, the member of the apparatus of the present invention contains dielectric material through which conduction of electric current does not take place or is negligible, and in which an electric field can be maintained with a minimum loss of energy. Examples of dielectric materials are porcelain, ceramics, glass, and polymers. The member can have several different kinds of designs. The member can be in the form of a bag filled with a fluid and/or an amount of solids. The bag can for example be made of a polymeric material and be filled with any kind of fluid, such as a liquid or gel, or filled with an amount of solids made of ceramics, e.g.. The member can also be in the form of one solid, e.g., made of ceramics. Advantageously, the dielectric constant of the member material is above 10. Further advantageously, the dielectric constant of the member material is be- tween 10 and 60, preferably between 30 and 40. Advantageously, the conductivity of the member material is also set to efficiently influence the input impedance of the antenna.

Further advantageously, the member is made of a recyclable material, such as a polymer. If the member is in the form of a bag, the bag can be made of a polymeric material filed with a recyclable gel. Hereby, the container provided with the member is easy to recycle, since the container and member consist of only cardboard and plastics. If the container is equipped with a package antenna made of metal as suggested by US 2006/0020300 A1 , the recycling process is

more complicated since the antenna has to be separated from the rest of the container.

The support of the packaging tray is the designed location for the IMD within the packaging tray, and can have many different kinds of designs. The sup- port can be in the form of a surface on which the front or rear side of the IMD is supported. The support can also be in the form of supporting members which press against the edges of the IMD and keeps it in position. In most cases, the support comprises a recess having a shape which is complementary to the shape of the IMD. According to an advantageous embodiment of the container according to the present invention, the support has such a configuration that the antenna of a stored implantable medical device is positioned in close proximity to the member.

Further advantageous embodiments of the apparatus, container and method according to the present invention, emerge from the enclosed claims and the detailed description of preferred embodiments.

Brief Description of the Drawings

The present invention will now be described, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, in which: Fig. 1 is a schematic perspective view of an embodiment of an IMD,

Fig. 2 is a schematic representation of the IMD of Fig. 1 , Fig. 3 is a top view of a first embodiment of the apparatus according to the invention,

Fig. 4 is a cross-sectional side view of the apparatus of Fig. 3, Fig. 5 is a cross-sectional side view of a second embodiment of the apparatus according to the present invention,

Fig. 6 is a cross-sectional side view of a third embodiment of the apparatus according to the present invention, and

Fig. 7 is a schematic flow diagram illustrating two embodiments of the method according to the present invention.

Detailed Description of Preferred Embodiments

Fig. 1 shows an IMD 102 having a hermetically sealed housing 104 and a connector header 106. The header 106 is provided with lead bores 108 for receiv-

ing leads having electrodes to be disposed in operative relation to a patient's heart. The IMD 102 is adapted to be implanted in body tissue. The header 106 is formed from a suitable dielectric material and houses an RF telemetry antenna 110 for wireless communication, which extends along the periphery of the header 106. The housing 104 of the IMD may contain a number of functionally elements and components of the IMD, including a battery, a processor, memory elements and a high voltage output capacitor.

Fig. 2 is schematic representation of the IMD 102 of Fig. 1. The housing 104 of the IMD contains RF transmitter/receiver circuitry 202 connected to the an- tenna 110. The RF transmitter/receiver circuitry 202 and antenna 110 are arranged to wirelessly communicate with an external device comprising transmitter/receiver circuitry and at least one antenna. Further, the housing 104 contains a therapy module 204 which may include electrical devices, microprocessors, controllers, memory elements and power supply. The therapy module 204 is arranged to provide the desired functionality associated with the IMD 102, e.g., defibrillation pulses, pacing simulation and patient monitoring. The therapy module 204 is arranged to be coupled to one or more therapy leads 206.

Fig. 3 shows a top view of a first embodiment of the apparatus according to the invention. The apparatus comprises an IMD 102 as shown in Fig. 1 and 2, and a container for storing the IMD 102 prior to implantation in body tissue. The container comprises a first sealable packaging tray 302 for housing the IMD 102, which first packaging tray 302 comprises a support in the form of a recess 304 for receiving and supporting the IMD 102. Further, the container comprises a second sealable packaging tray 306 for housing the first packaging tray 302. The trays 302, 304 are made of a suitable material, such as a rigid plastic material. The seals of the first and second packaging trays 302, 306 are excluded in Fig. 3. The apparatus comprises one member 308 positioned in proximity to the IMD 102, when stored in the container, and in proximity to said recess 304. More precisely, the member 308 is positioned in the close surroundings of the antenna 110 and the recess 304 has such a configuration that the antenna 110 of a stored IMD 102 is positioned in close proximity to the member 308. The member 308 extends along a substantial portion of the length of the antenna 110, and along the edge of the header 106, and advantageously, the member 308 abuts the header 106.

Fig. 4 is a cross-sectional side view of the apparatus of Fig. 3. The seal 402 of the first packaging tray 302 and the seal 404 of the second packaging tray 306 are shown in Fig. 4. Each seal 402, 404 consists of a sheet which is glued to a periphery contact face 406, 408 of respective packaging tray 302, 306. These seals are permeable to a sterilizing gas which is used during the packaging process. The first packaging tray 302 comprises an inner compartment 414 for receiving and retaining the member 308, and the member 308 is thus positioned on the inside of the first packaging tray 302. The member 308 is arranged to mechanically fixate the IMD 102 in its position in the first packaging tray 302. Fig. 5 is a cross-sectional side view of a second embodiment of the apparatus according to the present invention, comprising an IMD 102 and a member 308 corresponding to the IMD 102 and the member 308 of the embodiment of Figs. 3 and 4, but with a different container. Here, the inner packaging tray 502 is provided an external compartment 504 for receiving and retaining the member 308, and the member 308 is thus positioned on the outside of the inner packaging tray 502. This position of the member 308 is advantageous if the member 308 consists of a bag with gel or liquid. In case the bag is damaged during storage and gel leaves the bag, the gel will not contaminate the IMD 102.

Fig. 6 is a cross-sectional side view of a third embodiment of the appara- tus according to the present invention, comprising an IMD 102 and a member 308 corresponding to the IMD 102 and the member 308 of the embodiment of Figs. 3 and 4, but with a different container. In this embodiment, the outer packaging tray 602 is provided with an external compartment 604 for receiving and retaining the member 308, and the member 308 is thus positioned on the outside of the outer packaging tray 602. The inner packaging tray 606 is provided with a compartment 608 for receiving the external compartment 604 of the outer packaging tray 602, such that the member 308 is positioned in close proximity to the header 106 of the stored IMD 102. This position of the member 308 is advantageous if the member 308 consists of a bag with gel or liquid. In case the bag is damaged during storage and gel leaves the bag, the gel will not contaminate the sterilized environment on the inside of the outer packaging tray 602, and thus not contaminate the outside of the inner packaging tray 606.

The member could also be positioned on the outside of the second packaging tray and still be in proximity to the antenna of the IMD.

Since two sealable packaging trays are used, the whole inner tray will be kept sterile during storage, i.e. including the outside of the inner tray and the inside of the outer tray. This is advantageous in the surgical theatre during the implementation process when the IMD will be unpacked. In the above-mentioned embodiments of the apparatus, the member 308 comprises a bag 308 filled with a gel. The dielectric constant and conductivity of the member 308 are set such that the input impedance of the antenna 110 is adjusted to improve receive and transmit properties of the antenna 110 when the implantable medical device is stored in the container. The dielectric constant of the member is between 10 and 60, and more precisely between 30 and 40.

By altering the electrical material properties of the container in the surroundings of the antenna of the IMD such that they better correspond to the electrical material properties of body tissue, the input impedance of the antenna, when the IMD is stored in the container, corresponds better to the input impedance of the antenna when the IMD is implanted and located in body tissue, whereby the antenna is matched to the transmitter/receiver circuitry of the IMD also when the IMD is stored in the container. Hereby, the efficiency of the antenna outside the body tissue is improved, and thus the telemetry communication between an external device and an implantable medical device stored prior to implantation is im- proved.

The invention also relates to a container as described above and as claimed in the claims, comprising said member.

Fig. 7 is a schematic flow diagram illustrating two embodiments of the method according to the present invention, which first embodiment comprises the steps of providing an inner packaging tray with a compartment on the inside of the inner packaging tray, at 701 , and fixating the above-mentioned bag in the compartment on the inside of said tray, at 702. The inner packaging tray is placed inside an outer packaging tray, at 703. An IMD is placed in a recess formed by the inner packaging tray, at 704, such that bag is positioned in the close surroundings of the antenna and along a substantial portion of the length of the antenna. The IMD is mechanically fixated in its position in the recess by means of the bag, at 705. The inner tray is sealed, at 706, and the outer packaging tray is sealed, at 707, whereby the outer packaging tray fully encloses the inner packaging tray. The interior of outer packaging, including the inner packaging tray, is sterilized by

guiding a sterilizing gas through the permeable seal of the outer and the inner packaging tray, at 708. Finally, the packaging trays are inserted in a box, e.g., a cardboard box.

The second embodiment of the method according to the present invention comprises the steps of providing an inner packaging tray with a compartment on the outside of the inner packaging tray, at 801 , and fixating the above-mentioned bag in the compartment on the outside of the inner packaging tray, at 802. The inner packaging tray is placed inside an outer packaging tray, at 803. An IMD is placed in a recess formed by the inner packaging tray, at 804, such that bag is po- sitioned in the close surroundings of the antenna and along a substantial portion of the length of the antenna. The following steps 805, 806 and 807 correspond to the above-mentioned steps 706 to 708.

Alternatively, the outer packaging tray is provided with a compartment on the outside of the outer packaging tray, and said bag is fixated in this compartment on the outside of the outer packaging tray.

Naturally, in other embodiments falling within the scope of the claims, some of the above-mentioned steps can be performed in a different order.