IMPLANTABLE PULSE GENERATOR FOR TWO-STAGE THERAPY

Abstract

An implantable medical device for generating electrical stimulations, wherein the medical device is embodied to generate and emit, during a first stimulation phase, at least one first stimulation that has a first amplitude by means of energy from an energy storage element, and wherein the medical device is embodied, during a second stimulation phase following the first stimulation phase, to generate and emit at least one second stimulation that has a second amplitude by means of energy from the energy storage element, wherein the energy storage element is charged at least prior to the generation of the at least one first stimulation and after the generation of the at least one first stimulation, and wherein the medical device is embodied not to completely discharge the energy storage element by generating the at least one first stimulation. The invention furthermore relates to a method for controlling such a device.

Claims

1. An implantable medical device for generating electrical stimulations, wherein the medical device is embodied to generate and emit, during a first stimulation phase, at least one first stimulation that has a first amplitude by means of energy from an energy storage element, and wherein the medical device is embodied, during a second stimulation phase following the first stimulation phase, to generate and emit at least one second stimulation that has a second amplitude by means of energy from the energy storage element, wherein the energy storage element is charged at least prior to the generation of the at least one first stimulation and after the generation of the at least one first stimulation, and wherein the medical device is embodied not to completely discharge the energy storage element by generating the at least one first stimulation.

2. The implantable medical device according to claim 1, wherein the second amplitude is greater than the first amplitude.

3. The implantable medical device according to claim 1, wherein the implantable medical device has an energy source and a charging circuit, the charging circuit being configured to charge the energy storage element up to a target energy level (E.sub.z) by means of the energy source.

4. The implantable medical device according to claim 3, wherein the implantable medical device has a control unit, the control unit being configured to initiate the generation and emission of at least a first stimulation when charging the energy storage element before the energy level (E.sub.c) of the energy storage element has achieved the target energy level (E.sub.z).

5. The implantable medical device according to claim 4, wherein the control device is configured to initiate the generation and emission of the at least one second stimulation only if the target energy level (E.sub.z) has been achieved during charging of the energy storage element.

6. The implantable medical device according to claim 1, wherein the implantable medical device has a detection unit that is embodied to detect events from a tissue stimulated by means of the stimulations.

7. The implantable medical device according to claim 6, wherein the control unit is configured to initiate the generation and emission of the at least one second stimulation when one or a plurality of detected events satisfy a predefined criterion.

8. The implantable medical device according to claim 1, wherein the energy of the at least one stimulation or the total energy of a plurality of first stimulations in the first stimulation phase is less than the energy of the at least one second stimulation or is less than the total energy of a plurality of second stimulations in the second stimulation phase.

9. The implantable medical device according to claim 1, wherein the at least one second stimulation is designed for defibrillation of a patient's heart.

10. A method for controlling an implantable medical device, in particular an implantable medical device according to claim 1, comprising the steps: Emitting at least a first stimulation from an energy storage element of the device during a first stimulation phase, the at least one first stimulation having a first amplitude, and Emitting at least one second stimulation from the same energy storage element during a second stimulation phase following the first stimulation phase, the at least one second stimulation having a second amplitude, wherein the energy storage element is charged at least prior to and following the emission of the at least one first stimulation, and wherein the energy storage element is not completely discharged by the at least one first stimulation.

11. The method according to claim 10, wherein the second amplitude is greater than the first amplitude.

12. The method according to claim 10, wherein the energy storage element is charged up to a target energy level (E.sub.z).

13. The method according to claim 12, wherein the at least one first stimulation is emitted before the energy level (E.sub.c) of the energy storage element has achieved the target energy level (E.sub.z).

14. The method according to claim 13, wherein the at least one second stimulation is not emitted until the target energy level (E.sub.z) has been achieved during charging of the energy storage element.

15. The method according to claim 10, wherein events from tissue to be stimulated by means of the stimulations are detected by means of the device, the at least one second stimulation being emitted when at least one detected event satisfies a predefined criterion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Embodiments and features of the present invention shall be explained in the following using the figures.

[0086] FIG. 1 depicts one embodiment of the inventive implantable medical device;

[0087] FIG. 2 depicts a temporal curve for a first and a second stimulation phase performed with the device; and

[0088] FIG. 3 depicts typical parameters of stimulation pulses that are generated by means of the inventive device.

DETAILED DESCRIPTION

[0089] In conjunction with FIGS. 2 and 3, FIG. 1 depicts an embodiment of an inventive medical device 110 for generating electrical stimulations, wherein the device 110 is implantable in a body 100 of a person or patient, and wherein the medical device 110 is preferably embodied to generate and emit into tissue 160 or an organ 160 of the body 100, during a first stimulation phase 200, at least one first stimulation 240 (optionally another first stimulation 241) that has a first amplitude by means of energy from an energy storage element 125, and wherein the medical device 110 is furthermore embodied, during a second stimulation phase 210 following the first stimulation phase 200, to generate and emit into the tissue/organ 160 at least one second stimulation 250 that has a second amplitude by means of energy from the energy storage element 125, wherein the energy storage element 125 is charged at least prior to the generation of the at least one first stimulation 240 and after the generation of the at least one first stimulation 240, and wherein the medical device is embodied not to completely discharge the energy storage element 125 by the generation of the at least one first stimulation 240.

[0090] The present invention thus permits a two-stage, e.g. antitachycardia, therapy, wherein in particular during the charging of the energy storage element 125 for the second therapy or stimulation phase 210 a first stimulation 240 is emitted that is supplied from the same energy storage element 125 and preferably uses the same electrodes 135 as the subsequent second stimulation/therapy 250. The first stimulation phase 200 is characterized in that it typically acts increasingly more aggressively as voltage increases in the energy storage element 125 in preparation for the second stimulation phase and there is a high probability of success for ending the tachycardia during this first stimulation phase 200. If this is not the case, the second stimulation phase 210 takes place. The first stimulation phase 200 is also characterized in that it requires significantly less energy and is more protective of the organ.

[0091] In detail, the device 110 according to FIG. 1 may be designed, e.g. as an implantable pulse generator 110 that emits the individual stimulations 240, 241, 250 in the form of stimulation pulses. According to one embodiment, the pulse generator or the device 110 has an energy source 115 (e.g. battery), an energy storage element 125, a charging circuit 120, a control unit 140, and a detection unit 145 that registers events from the tissue 160. The device 110 furthermore preferably has a therapy unit 130 for generating the stimulations/stimulation pulses, the therapy unit 130 emitting the stimulations/stimulation pulses into the tissue 160 via a tissue interface 135 to the tissue 160 to be provided therapy (e.g. in the form of electrodes). Moreover, the device 110 may have a telemetry unit 150.

[0092] FIG. 2 depicts the temporal curve of a typical inventive realization of the two-phase therapy comprising a first stimulation phase 200 and a second stimulation phase 210. As long as the energy level in the energy storage element 125 is below the target energy level E.sub.z, charging occurs at the charging speed 220. The stimulation pulses 240 and 241 are emitted during the course of this first stimulation phase 200. A criterion detected by the detection unit 145 preferably introduces the second stimulation phase 210. In doing so, where necessary charging must continue up to the target energy level E.sub.z, which here optionally occurs at a different charging speed 230. Once the target energy level has been achieved, the at least one stimulation pulse 250 (optionally a plurality of second stimulation pulses) of the second stimulation phase is emitted.

[0093] FIG. 3 provides an exemplary depiction of the typical parameters of the stimulation pulses 240, 241, 250 the inventive device 110 generates according to one embodiment. In the example shown, these are changing polarity (e.g. of the first stimulation phase 200), the amplitudes 300, 301, and 302, the pulse widths 310, 311, and 312, and the intervals 320 and 321 until the next stimulation pulse.

[0094] The inventive solution reaches greater areas in the organ to be provided therapy just in the first stimulation phase 200 than is possible using ATP, and specifically in particular due to a far field effect and the higher possible voltages compared to conventional pacing stages. The far field effect in this context describes the effect that a stimulation pulse generates excitation fronts in tissue areas farther way from the stimulation site. The far field effect may be amplified by overlaying stimulation pulses. One advantage of the stimulation effect s in the far field effect is the more homogeneous distribution of the stimulation energy in the tissue. Thus the tissue in the far field is stimulated without points of higher energy density, so that it is possible to prevent tissue damage. The inventive solution makes possible a progressive increase in the effect not only by timing (as for conventional ATP, ramping, coupling, etc.), but also in particular due to the increasing amplitudes of the stimulation pulses 240, 241, etc. Due to a smaller duty cycle and lower peak voltages, this first therapy stage also requires significantly less energy than a high energy therapy; however, for safety reasons high energy therapy is also possible immediately in principle.

[0095] It will be apparent to those skilled in the art that numerous modifications and variations of is the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points.