INTRAVASCULAR IMPLANT SYSTEM

Abstract

An intravascular implantable system for providing electrical stimulation of tissue inside an animal to deal with a clinical condition is described. The system comprises a power supply module supplying energy to the implantable system, an implanted control module controlling operation of the implantable system and producing desired digital waveforms. Each desired digital waveform has an envelope with a predetermined attribute. An implanted intravascular sensing module sensing at least one parameter of interest for the purpose of dealing with the clinical condition. An intravascular stimulation module is provided to electrically stimulate the tissue with an output waveform that is substantially similar to the desired digital waveform produced by the control module.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a representation of and intravascular medical device is used as a cardiac pacing system attached to a medical patient;

FIG. 2 is an isometric, cut-away view of a patient's blood vessels in which a receiver antenna, a stimulator and an electrode of the intravascular medical device have been implanted at different locations;

FIG. 3A is a schematic of an exemplary wireless intravascular platform for tissue stimulation illustrating external and internal components;

FIG. 3B is a block schematic diagram of the exemplary wireless intravascular platform illustrating extravascular and intravascular components;

FIG. 4A is a schematic diagram of part of the controller providing a three-state output;

FIG. 4B is the table showing the relationship between signal state and the output;

FIG. 4C is an exemplary signal waveform;

FIG. 4D is the table showing the relationship between output signals and logical states corresponding to the signal waveform in FIG. 4C;

FIG. 4E is an exemplary analog amplifier;

FIG. 4F depicts the losses incurred during driving the analog amplifier;

FIG. 4G shows a pulse width modulated signal in a unipolar option;

FIG. 4H shows a pulse width modulated signal in a bipolar option;

FIG. 4I illustrates decoding an arbitrary desired waveform that is encoded by PWM signal via a biological filter;

FIG. 4J shows a desired digital waveform going through a biological filter and retaining its final shape;

FIG. 5 is a illustrates the application landscape of the generalized wireless intravascular platform;

FIG. 6 schematically depicts an alerting system enabled by the wireless intravascular platform;

FIG. 7 is a block schematic diagram of a monitoring system enabled by the wireless intravascular platform;

FIGS. 8A and 8B are schematic diagrams of an sensing amplifier system enabled by the wireless intravascular platform;

FIGS. 9-12 are schematic representations of various attributes of a detection system enabled by the wireless intravascular platform;

FIG. 13 is a block schematic diagram of a classification method enabled by the wireless intravascular platform;

FIG. 14A depicts a circuit of a high impedance lead in a prior art system;

FIG. 14B shows the circuit of the system enabled by the proposed method;

FIG. 15 is the representation of one period of a standard pulse;

FIG. 16 is the representation of one period of one form of the proposed composite pulse;

FIG. 17 is the representation of one period of an alternative form of the proposed composite pulse;

FIG. 18 is a schematic of the arterial stimulation from an adjacent vein;

FIG. 19 is a schematic of the hybrid treatment system enabled by the wireless intravascular platform;

FIG. 20 is a schematic of the energy supply and control signal provided by the wireless intravascular platform to an implanted sensing and monitoring device;

FIG. 21 is a schematic of the energy supply and control signal provided by the wireless intravascular platform to an implanted sensing and treatment/therapy device;

FIG. 22 is a schematic of the energy supply and control signal provided by the wireless intravascular platform to an implanted sensing and monitoring device; and

FIG. 23 is a schematic of the energy supply and control signal provided by the wireless intravascular platform to an implanted supporting device.

DETAILED DESCRIPTION OF THE INVENTION

Although the present invention is being described in the context of implanted components of a cardiac pacing system, it can be used in the implanted components for other types of medical devices in an animal's body. Furthermore, the present apparatus and method are not limited to implanted items in a therapy providing system, but can be employed to implanted elements for other purposes in the animal as described in subsequent paragraphs.

Initially referring to FIG. 1, a cardiac pacing system 10 for electrically stimulating a heart 12 to contract comprises an external power source 14 and a medical device 15 implanted in the circulatory system of a human medical patient. The medical device 15 receives a radio frequency (RF) signal from the power source 14 worn outside the patient and the implanted electrical circuitry is electrically powered from the energy of that signal. At appropriate times, the medical device 15 delivers an electrical stimulation pulse into the surrounding tissue of the patient.

The power source 14 may be the same type as described in U.S. Pat. Nos. 6,445,953 and 6,907,285 and includes a radio frequency transmitter that is powered by a battery. The transmitter periodically emits a signal at a predefined radio frequency that is applied to a transmitter antenna in the form of a coil of wire within an adhesive patch 22 that is placed on the patient's upper arm 23. In a basic version of the cardiac pacing system 10, the radio frequency signal merely conveys energy for powering the medical device 15 implanted in the patient. In other systems, the transmitter modulates the radio frequency signal with commands received from optional circuits that configure or control the operation of the medical device 15.

Referring to FIGS. 1 and 2, the exemplary implanted medical device 15 includes an intravascular stimulator 16 located a vein or artery 18 in close proximity to the heart. Because of its electrical circuitry, the stimulator 16 is relatively large requiring a blood vessel that is larger than the arm vein, e.g. the basilic vein, which is approximately five millimeters in diameter. Therefore, the stimulator 16 may be implanted in the superior or inferior vena cava. However, it is contemplated that miniaturization of components can allow the electrical circuitry needed to be much smaller the example cited above. Electrical wires lead from the stimulator 16 through the cardiac vascular system to one or more locations in smaller blood vessels 19, e.g. the coronary sinus vein, at which stimulation of the heart is desired. At such locations, the electrical wire 25 are connected to a remote electrode 21 secured to the blood vessel wall.

Because the stimulator 16 of the medical device 15 is near the heart and relatively deep in the chest of the human medical patient, a receiver antenna 24 for the RF signal is implanted in a vein or artery 26 of the patient's upper right arm 23 at a location surrounded by the transmitter antenna within the arm patch 22. That arm vein or artery 26 is significantly closer to the skin and thus receiver antenna 24 picks up a greater amount of the energy of the radio frequency signal emitted by the power source 14, than if the receiver antenna was located on the stimulator 16. Alternatively, another limb, neck or other area of the body with an adequately sized blood vessel close to the skin surface of the patient can be used. The receiver antenna 24 is connected to the stimulator 16 by a micro coaxial cable 34.

As illustrated in FIG. 2, the intravascular stimulator 16 has a body 30 constructed similar to well-known expandable vascular stents. The stimulator body 30 comprises a plurality of wires formed to have a memory defining a tubular shape or envelope. Those wires may be heat-treated platinum, Nitinol, a Nitinol alloy wire, stainless steel, plastic wires or other materials. Plastic or substantially nonmetallic wires may be loaded with a radiopaque substance which provides visibility with conventional fluoroscopy. The stimulator body 30 has a memory so that it normally assumes an expanded configuration when unconfined, but is capable of assuming a collapsed configuration when disposed and confined within a catheter assembly, as will be described. In that collapsed state, the tubular body 30 has a relatively small diameter enabling it to pass freely through the vasculature of a patient. After being properly positioned in the desired blood vessel, the body 30 is released from the catheter and expands to engage the blood vessel wall. The stimulator body 30 and other components of the medical device 15 are implanted in the patient's circulatory.

The body 30 has a stimulation circuit 32 mounted thereon and, depending upon its proximity to the heart 12, may hold a first electrode 20 in the form of a ring that encircles the body. Alternatively, when the stimulator 16 is relatively far from the heart 12, the first electrode 20 can be remotely located in a small cardiac blood vessel much the same as a second electrode 21. The stimulation circuit 32, which may be the same type as described in the aforementioned U.S. patents, includes a power supply to which the micro coaxial cable 34 from the receiver antenna 24 is connected. The power supply utilizes electricity from that antenna to charge a storage capacitor that provides electrical power to the stimulation circuit. A conventional control circuit within the stimulation circuit 32 detects the electrical activity of the heart and determines when electrical pulses need to be applied so that the heart 12 contracts at the proper rate. When stimulation is desired, the stimulation circuit 32 applies electrical voltage from its internal storage capacitor across the electrodes 20 and 21. The second electrode 21 and the first electrode when located remotely from the stimulator 16, can be mounted on a collapsible body of the same type as the stimulator body 30. In all the examples cited with regard to the FIG. 2, it should be understood that the example size limit is driving the decision on the placement of components. It is contemplated that miniaturization of components can lead to many more options for component placement.

FIG. 3A shows the schematic of a wireless intravascular platform 102 for tissue stimulation illustrating external components 104 located outside the body of an animal and internal components 142 located inside the body of the animal. The external components 104 include a battery 105, power transmitter 110, power feedback module 115, a communication module 120 and a monitor 125. The external components may optionally include a wireless communication module 130 to communicate with external devices (not shown).

Battery 105 is rechargeable allowing for patient mobility with periodic recharge cycles. With battery volume, the time between recharge cycles can be proportioned to cover days, months or years. Power transmitter 110 is a modulated transmitter proportioned to provide maximum power with an adjustable duty cycle to meet the power demands. Power feedback module 115 is part of closed loop system composed of power transmitter, implanted component 150 comprising of an RF receiver coil and an electronics capsule and a feedback algorithm to supply a required amount of power. The control loop converts the receiver voltage into a frequency shift of the secondary re-transmitter. Consequently, a drop in received voltage would cause an increase in the retransmitted frequency. (E.g. on a 100 MHz signal, this would be a 10 to 50 kHz shift per 100 mV). Since the power consumption is a function of the number of pacing events, the power level itself could vary. By maintaining a constant voltage, it is ensured that only the needed amount of power is transmitted.

Communication module 120 receives logged data collected from the implant device. This data can be physiological data and a set of trending logs indicating patient and/or device condition over time. Trending logs can be accumulated continuously by the receiver CPU by keeping the highest time resolution for the most recent events in minutes, the mid-range events hours, and long range events in days etc. Alternatively, the logged data can have a fixed size, wherein the actual storage of data can be done externally. Internally, since the CPU has a limited space, one may choose to maintain the most recent data at a higher time resolution. As another alternative, the data from the implant can be streamed in real-time to an external storage and the externally stored data can be analyzed for the trends. In one embodiment, for reporting purposes, one could extract data around events, e.g. time prior to the detection of arrhythmias, and time after pacing attempts to restore the rhythm. For the purposes of patient management, for instance, the data from the implant could alert the physician when conditions requiring quick follow up such as atrial fibrillation requiring anticoagulation occurred. Other physiological parameters such as change in blood volumes, heart rate variability, pressure changes, and blood sugar can be used for short and long term trending for internal monitoring and alerting.

The communication module 120 also provides an access point into the system to communicate to the caregiver or to alert a caregiver remotely by means of auto-dialup, for example, in case an alerting condition presents itself. Monitor 125 monitors the received data.

Again referring back to FIG. 3A, the internal components 142 include the implanted component 150 mentioned above consisting of an RF receiver coil and an electronics capsule located in a large vessel 145. One example of such a vessel is inferior vena cava (IVC). In one exemplary embodiment leads 152 and 154 are used for pacing and sensing the heart 144 respectively.

The Generalized Wireless Intravascular Platform

The generalized form of the wireless intravascular platform described above is summarized in FIG. 3B. It has both an intravascular component 173 and an extravascular component 175. The extravascular component may be implanted or extracorporeal.

Power Supply:

The core of the platform consists of a power source 179 that is extravascularly located and employs wireless transmission of power to operate the intravascular platform. It has a computer 181 that is used to perform a number of functions including overall control logic, processing algorithms, data and power encoding and determination of optimal response based on the feedback. A signal generator 177 is associated when needed with the extravascular part of the platform to send data to the intravascular component 173 via a wireless power-data transmitter/receiver 171.

A discriminator circuit may be used to separate power and data components transmitted from extravascular component. The received power can be used for the intravascular operation by rectifying the power signal into DC by a rectification circuit and used to power the internal control and other electrical/electronic circuitry. Alternatively, the received power can be used to charge a rechargeable battery based on the need and used to meet the energy demands of the intravascular platform. In some embodiments, a combination of the above may be used for meeting the energy demands. In some embodiments, the extravascular component may have a non-rechargeable battery that powers the intravascular component. In some embodiments, the extravascular component may have a rechargeable power supply that may be charged by resonant, near-field inductive coupling, which is described below.

The main aspect of the power supply is an implanted resonant receiver coil which is inductively coupled to the input power source. A resonant receiver coil permits a higher collected energy density for a given receiver coil volume. In a resonant receiver coil, the induced voltages and currents are much higher than in a non resonant coil. As a result, a resonant coil with a given dimension and a high quality resonant circuit can collect more energy from a surrounding near-field than a non-resonant coil. A coil can be made resonant by adding a capacitor in parallel to create a parallel resonant circuit, or in series to create a series resonant circuit. The apparent impedance of the resonant circuit depends on the resistive loading on that tank circuit. The loading may be direct or indirect. In the case of a direct load, the load is placed directly across the resonant circuit. If the load is a linear resistor, it will have a dampening effect to lower the Q-value of the tank circuit and potentially nullify the benefit from the resonance. In the case of an indirect load, the load can be inductively or capacitively coupled externally. A load of this type is body tissue or blood pool.

Second, special precautions are taken to extract energy from the resonant circuit without excessive damping. For example, lowering the Q from 40 to 20 may be acceptable. However lowering the Q from 40 to less than 5 may not be. By using a capacitively coupled rectifier and using the rectifier to charge a buffer capacitor, the load is only presented to the resonant circuit when the rectifier is conducting. The time constant of the buffer capacitor and the load is chosen to allow, for example, a 1% droop in voltage between charge pulses. This effectively makes the load to appear only during the top 1% of the cycle. After initial charge-up, all that needs to be supplemented by the resonant circuit is at nearly full amplitude within the 1% mentioned in the exemplary case. The supplemented power is provided by a power feedback as previously described.

By combining these two aspects described above, an efficient energy source can be created. One additional aspect to consider is the transfer efficiency factor. Note that direct short wiring is the most efficient energy transfer with lowest resistance. For the wireless circuits, resonant coupled circuits are the most efficient with a high coupling factor when the primary (source) and the secondary (load) are next to each other with minimal space as in a near field scenario. In this case, the captured flux increases in a non-linear fashion. The resonant aspect focuses on a narrow band of the energy spectrum. The resonant energy has alternating electric fields coexistent with alternating magnetic fields. The energy may be derived from either one, as the fields are just a description of the two measurable aspects of the electromagnetic field transfer. However, the power dissipation in biological tissue is determined by the square of the electric field times the conductivity of the tissue divided by the density of the tissue for the computation of specific absorption rate (SAR). Therefore, the preferred energy transfer mechanism is via the B field. Antennas are designed such that E field is minimized. It should be noted that there are two types of electric fields: one is caused by varying magnetic field as described by Maxwell's equations, and will always be there. The other is caused by voltage sources. It is the latter aspect of the electric field that is minimized by the choice of magnetic field antennas. Hence these antennas are loops that carry current and generate magnetic field.

The extravascular component 175 communicates via a link 183 with an external device 185.

Controller:

A controller 163 controls the stimulation signal with a digital output delivered to the stimulation site. The control circuit stores the operational parameters for use in controlling operation of a stimulator that applies tissue stimulating segmented voltages pulses across a plurality of electrode pairs. Preferably, the control circuit comprises a conventional microcomputer that has analog and digital input/output circuits and an internal memory that stores a software control program and data gathered and used by that program. The controller also controls an electrical sensing device that does not have external grounding or referencing. The sensing device and the controller are connected to the tissue through a lead assembly with a plurality of dynamically programmable electrodes, which may or may not be shared with the pacing electrodes. Purpose specific segmented waveforms are delivered to the electrodes by the controller. The controller may be located at an intravascular location or located at a suitable subcutaneous location. The controller generates desired digital stimulation waveform.

A signal receiver/transmitter 167, when needed, may also function as a stimulator as in the exemplary embodiment described previously in FIGS. 2 and 3A. Both of the wireless power/data transceivers may be linked by feedback loops 169 in one direction and 169A in the other direction that may optimize the power and data transfer between the transceivers. The receiver/transmitter 167 may be located at an intravascular location and may receive signals from the waveform generator using a wireless means. As in case of the example above, the reception may be from a near-field, resonant inductive coupling. Stimulator 165 when needed may be located at a suitable intravascular location. It has stimulation leads that may be directly wired to the receiver or to the waveform generator. Sensors 161 when needed may be located at a suitable intravascular location in one embodiment as shown or they may be located subcutaneously (not shown). Sensors may be active requiring power from the power supply to operate or passive requiring no additional power from the external or an internal power source. Sensing leads when needed may be located at an intravascular location. Alternatively, they may be located at a subcutaneous location. In certain cases, the sensing leads may be connected to a generator directly. Alternatively the connection may be indirect, for example, through a resonant, near-field, inductive coupling. In some embodiments, electrodes and sensing leads may terminate in the vessel they are deployed. In this case, stimulation and sensing may be carried out in a transvascular manner. In some embodiments, electrodes and/or sensing leads may exit the vessel they are deployed through an opening in the vessel wall and may be directly anchored to the tissue to be stimulated and/or sensed from. In some embodiments, electrodes and/or sensors may be freely suspended in the blood steam of the vessel. The generalized form of the wireless intravascular framework described above can be used for several applications that will be described in detail below.

Waveform Synthesis:

As mentioned before, the controller has multiple roles. In this section, the role of controller in synthesizing waveforms for stimulation is described. The FIG. 4A shows a portion of the controller delivering a generic digital output, which has a tri-state mode. The “enable” function is used to “turn-on” the outputs such that they can produce logic state high or a logic state low. In these states the current can be “sourced” from high (supply rail, VS) to the output, or “sinked” from output to ground. In the third state, i.e., the high impedance state, the output current is always zero. Thus it provides infinite impedance. This is shown in FIG. 4B.

The output derived from two such output voltages now gives a differential output, or a difference between these two outputs. The output voltage relative to common level (Vcm) is not relevant since it may be subtracted out as shown below:

V ₀₁ =Vcm+V _0−A

V ₀₂ =Vcm+V _0−B

V ₀ =V ₀₁ −V ₀₂ =V _0−A −V _0−B

If V_0−A and V_0−B can only be “0” or “VS” or open, then the composite or differential V₀ can produce VS, −VS, 0, or open. Note that an “open” voltage is not equal to “0.” In FIG. 4C, an exemplary waveform is shown and its various voltages, logical states and output current through a load resistance RL are shown in FIG. 4D. Note that there is no reference to a system common or the external ground anywhere. By using the difference of two signals that each can be in one of three states, a multitude of waveform envelopes can be synthesized. This synthesis may not be possible by using the ground referenced single ended signals.

A conventional analog output which is shown in FIG. 4E. Note that the conventional analog output is inherently not energy efficient. This is indicated in FIG. 4F by highlighting area representing energy loss around the arbitrary waveform.

The envelope of the synthesized waveform may be determined or selected as a function of measurement a physiological characteristic which is sensed by an implanted and/or an external sensor. The sensed characteristic may be a naturally occurring or an evoked in response to the electrical stimulation from the implanted medical device. In one embodiment, externally sensed motion may be used in conjunction with an internally sensed heart rate to provide an adaptive algorithm for waveform envelope selection. In another embodiment, the envelope of the synthesized waveform is a function of a command signal transmitted to the implanted device via RF telemetry. In a further embodiment, the synthesized waveform's envelope is a function of preprogrammed clinical algorithm that may be application dependent. Such a preprogrammed clinical algorithm may be needed in an emergency care situation, for example. In a general case, the envelope of the synthesized waveform may be a function of an attribute that can be a sensed signal, received telemetry signal, or a preprogrammed clinical algorithm to mention only a few.

In a digital system, FIGS. 4G and 4H show how arbitrary waveforms can be encoded using digital output. The first one shown in FIG. 4G is a unipolar pulse width modulation (PWM) waveform that may be used for the case of a differential output. The second one shown in FIG. 4H is a bipolar PWM for the case of ground referenced outputs wherein the center line is the ground reference. The encoded signal is similar to naturally occurring neural firings into a muscle, which are PWM as well. There are two methods of PWM. The first one has fixed pulse width and variable frequency similar to the coding occurring in a neural system. Alternatively, one may use variable pulse width with fixed frequency.

FIG. 4I shows a simplified schematic of signal application to the tissue. The pulse width modulated signal is applied to the tissue. The body impedance characteristics are conveniently used as a biological filter. The resultant integration comes from the body tissue resistance combined with the natural tissue capacitances. The biological integrator, i.e., low-pass filter system, smoothes out the ripple thereby reconstructing/decoding the stimulation signal substantially similar to the desired signal synthesized by the controller. It should be noted that the resistance R of the low pass filter system includes both the body resistance and the system resistance. Since body resistance is constant but low, the system resistance needs to be substantially lowered compared to the traditional electrodes to minimize the distortion of the waveform including rounding of the corners and keep it substantially similar to the desired waveform.

Having described a general case, the preferred embodiment is described below. In the preferred embodiment, the controller delivers segmented digital waveforms whose voltage envelope is chosen such that it is close to the desired output voltage. In such a device capture threshold is managed by modifying the duration of the output waveform to minimize energy losses at the output stage. In this case as shown in FIG. 4J, since the waveform is already in the digital form, one may not need to use PWM. As mentioned before, the system resistance needs to be substantially lowered compared to the traditional electrodes to minimize the distortion of the waveform and keep it substantially similar to the desired waveform. The segmented, stimulation waveforms may pass through a voltage intensifier stage based on a specific purpose. As an example of an application requiring voltage intensification stage, an atrial defibrillation treatment device may require a high voltage (10-30 volts) and high rate of 1200 beats/minute (BPM). As an example for an application that does not require voltage intensification, a pacing device to treat bradycardia may need a low voltage (2-5 volts) and low rate (40-120 beats/minute).

APPLICATIONS

Application Paths:

Using a wireless intravascular platform in its generalization, several application paths may be defined. FIG. 5 illustrates a matrix of potential application paths definable and contemplated by the aspects of wireless intravascular platform. Each contemplated application path may include one or more components of one or more of an attribute of a clinical condition (A) 190, a clinical purpose attribute (B) 191, a temporal attribute (C) 192, a parameter attribute (D) 193 and a body part attribute (E) 194. These sub-components may form a series of non-mutually exclusive listings. However, not all of the paths possible by the listings are novel. Rather, specific paths adapted for specific care purposes and specific body parts using the wireless intravascular platform (WIVP) are contemplated. The combinations of WIVP application paths are constructed with at least one of the attributes of A, B, C and D in the following combinations. Accordingly, wireless intravascular platform for attributes A, B, A+B, B+C, A+C, A+D, B+D, C+D, A+B+C, B+C+D, A+C+D, A+B+D, A+B+C+D are contemplated. Here the “+” notation is to indicate the Boolean “AND” operation. These paths are further explained in the examples below.

Wireless intravascular platform for A: Wireless intravascular platform for treating at least one clinical condition; examples: wireless intravascular platform for CHF resynchronization therapy; and wireless intravascular platform for CHF therapy involving non-pharmacologic inotropic stimulation.

Wireless intravascular platform for B: Wireless intravascular platform for a clinical purpose; Example: Wireless intravascular platform for CHF resynchronization therapy monitoring.

Wireless intravascular platform for B “AND” A: Wireless intravascular platform for a clinical purpose attribute to act on a clinical condition attribute; Example: Wireless intravascular platform for monitoring patients during CHF resynchronization therapy.

Wireless intravascular platform for C “AND” B: Wireless intravascular platform for an implanted device control. Example: Wireless intravascular platform for an event triggered insulin pump control.

Wireless intravascular platform for C “AND” A: Wireless intravascular platform for temporal attribute manipulating an implanted device in response to a clinical condition. Example: Wireless intravascular platform for an event triggered cardiac pacing for CHF patients.

Wireless intravascular platform for D “AND” B: Wireless intravascular platform for parameter attribute manipulating a clinical purpose to treat a patient. Example: Wireless intravascular platform for remote monitoring of electrical parameters of chronic cardiac failure patients.

Wireless intravascular platform for C “AND” D: Wireless intravascular wireless platform for temporal attribute to modulate parameter attribute. Example: Wireless intravascular platform for continuous intravenous pressure measurement.

Wireless intravascular platform for C “AND” D with B: Wireless intravascular wireless platform for temporal attribute to modulate a parameter attribute to achieve a clinical purpose (i.e., one or multi-parameter and one or multi-purpose). Example: Wireless intravascular platform for periodically alerting a caregiver on a patient's vital signs.

Wireless intravascular platform for C “AND” D with A: Wireless intravascular wireless platform for a temporal attribute to modulate a parameter attribute to treat a clinical condition. Example: Wireless intravascular platform for periodically monitoring electrolyte levels during GI tract stimulation.

Wireless intravascular platform for D with B and A: Wireless intravascular platform for a parameter value driven therapy modification. Example: Wireless intravascular platform for cardiac signal (ECG) based electrical stimulation treatment of CHF.

Wireless intravascular platform for B on A with C: Wireless intravascular platform for a clinical purpose attribute to act on a clinical condition attribute using a temporal attribute. Example: Wireless intravascular platform for deep brain stimulation for epileptic seizures based on temporal EEG signal analysis.

Wireless intravascular platform for B on A with C and D: Wireless intravascular platform for a clinical purpose attribute to act on a clinical condition attribute using a temporal attribute in conjunction with a parameter attribute. Example: Continuous glucose monitoring to control the amount of electrical stimulation for chronic obesity treatment.

Wireless intravascular platform for multiple B: Wireless intravascular platform for therapy convergence. Example: Wireless intravascular platform to perform a number of treatment options including electrical stimulation treatment and drug treatment.

As illustrated with the last scenario, it should be understood that two or more options within the same attribute, B in the above scenario, can also be combined in a desired application.

Alerting:

FIG. 6 schematically illustrates functional aspects of the alerting system enabled by the intravascular platform. The alerting system comprises several sub-components. The first sub-component, which is located inside the body of an animal, is the data input component 200 that collects processed and/or unprocessed data for physiological monitoring and system performance. An example for the system performance parameters that could be monitored is the energy transfer efficiency, which would be zero if the external component 102 shown in FIG. 3 were removed from the patient. The data is initially accessed by a computer in the implanted component 210 and is communicated to the external device through wireless means 220 for processing by the external component 235.

The second sub-component, which is part of the external component, is a data processing device 230, interpreting the presented data and comparing these to preset or programmable thresholds, which include static or dependant variables, such as rates that change with time. For example, a threshold could be the maximum allowable change of the heart rate. Another example of a variable can be the energy consumption over time.

The third sub-component is one or more of the communication devices that could be one or more of the following: audio means 24) for generating sounds at various levels; display means 250 for generating simple lights to text or waveforms or video or combination displays; and audio and voice using pre-recorded messages, associated with conditions and/or measurements. For example, an audio signal could indicate when an optimal relative position of external and internal components has not been achieved. In this example, a user can reposition the external component to minimize the audio signal, which falls below the audible range when optimal relative position is achieved. A second example could be a message indicating that the device should be repositioned on the patient. The message stops when the device is properly repositioned.

The fourth component is auto-communicator 270 that interface via signal path 260 with the data processing device 230. In one example, it could be a portion of a cell phone or a comparable wireless means 280 that calls a responsible party, a target recipient 295, that may be a caretaker, a primary physician, or a relative. This call may be directly to the target recipient or through a service provider 290. The wireless means may also call for service 285 in case of a device break down or when service is required. In another example, an acoustical warning emanated from the system, in the form of a subtle beep to prompt the user to activate the message system, which can be initiated in a suitable location to provide privacy if needed. In another example, the alerting mechanism can activate sound, or light if the device is dislodged and no longer with the patient. This alert enables localization of the external component and assist retrieve the component. In the same example, if no action takes place for a pre-determined time, the next level of alerting can be initiated.

In yet another example, if the data indicates either a serious condition of the patient, for example, absence of heartbeat for a pre-specified amount of time, or failure to attach the device, an automatic call can be placed using conventional existing cell phone networks. A prerecorded message, along with physiological data, where applicable, can be transmitted to the target audience. The prerecorded message can also be accessed by the target audience when their designated pager is activated.

It should be noted that the data transfer may not be a scheduled data transfer, but rather an impromptu situation-based, autonomous communication to allow corrective action at a tiered level, commensurate to the situation. In autonomous operation, the device will take action based on a set of criteria and circumstance. In some embodiments, environmental variables, such as air pressure, air temperature and skin temperature may be incorporated to correlate with physiological data prior to a communication decision being made.

As previously noted, the communication signal could be one or more of the following in the form of a low level audible alarm, an escalated audible alarm, a dial out, a dial out and voice exchange—as in comparable cell phone function, a data exchange or a multi-media data exchange.

With regards to the intravascular implanted system, it is capable of self monitoring, physiological monitoring and autonomously alerting the patient, a bystander, a remote expert, a networked computer, a service person or a relative. Thus it is further intended to include alerting mechanism to communicate with different, independent communicable targets based on both the needs of the device and the patient based on pre-determined conditions. In a first example, a caretaker can be alerted if internal and external components do not communicate with each other for a predetermined time. In a second example, the alerting mechanism may contact a medical service or physician if abnormal rhythms are observed. In a third example, the alerting mechanism may trigger a service call if communication is present but battery power is lower than a predetermined value.

Monitoring:

FIG. 7 schematically illustrates functional aspects of the monitoring system enabled by the intravascular platform of FIG. 4. The monitoring system involves sensing a physiological event and following it in time. The monitoring system mainly consists of intravascular component 310 and an extravascular component 324. Both these components may have several sub-components.

Now referring to he component 310, the first sub-component, which is located inside the body of an animal, is the sensing component 302 that senses the physiological parameter via one or more transducers. For example, the sensors of the present invention may be employed to provide measurements of volume. flow rate, pressure, temperature, electrical parameters, biochemical characteristics, or the amount and type of deposits in the lumen of an intravascular implant, such as a stent or other type of intravascular conduit. The present invention also provides a means to modulate mechanical and/or physical properties of the intravascular implant in response to the sensed or monitored parameter. Quantitative in vivo measurements of volumetric flow rate, flow velocity, biochemical constitution, fluid pressure or similar

physical or biochemical property of the body fluid through an intravascular device would provide more accurate diagnostic information to the medical practitioner. As used herein, the term “intravascular device” is intended to include stents, grafts and stent-grafts which are implanted within an anatomical passageway or are implanted with a body to create a non-anatomical passageway between anatomically separated regions within the body. The term “sensor,” as used herein, includes, without limitation, biosensors, chemical sensors, electrical sensors and mechanical sensors. While the term “biosensor” has been used to variously describe a number of different devices which are used to monitor living systems or incorporating biological elements, the International Union for Pure and Applied Chemistry (IUPAC) located in Research Triangle Park, N.C., U.S.A. has recommended that the term “biosensor” be used to describe “a device that uses specific biochemical reactions mediated by isolated enzymes, immunosystems, tissues, organelles or whole cells to detect chemical compounds usually by electrical, thermal or optical signals.” The term “chemical sensor” is defined by the IUPAC as a device that transforms chemical information, ranging from concentration of a specific sample component to total composition analysis, into an analytically useful signal. Conventional biosensors are a type of chemical sensor that consists of three basic elements: a receptor (biocomponent), transducer (physical component) and a separator (membrane or coating of some type). The receptor of a chemical sensor usually consists of a doped metal oxide or organic polymer capable of specifically interacting with the analyte or interacting to a greater or lesser extent when compared to other receptors. In the case of a biosensor the receptor or biocomponent converts the biochemical process or binding event into a measurable component. Biocomponents include biological species such as: enzymes, antigens, antibodies, receptors, tissues, whole cells, cell organelles, bacteria and nucleic acids. The transducer or physical component converts the component into a measurable signal, usually an electrical or optical signal. Physical components include: electrochemical devices, optical devices, acoustical devices, and calorimetric devices as examples. The interface or membrane separates the transducer from the chemical or biocomponent and links this component with the transducer. They are in intimate contact. The interface separator usually screens out unwanted materials, prevents fouling and protects the transducer. Types of interfaces include: polymer membranes, electropolymerized coatings and self-assembling monomers.

The second sub-component is the data input component 304 that collects processed and/or unprocessed data for physiological monitoring and system performance. An example for the system performance parameters that could be monitored is the energy transfer efficiency, which would be zero if the external component 102 shown in FIG. 3 were removed from the patient. The data is initially accessed by a computer in the implanted component 308 and is communicated to the external device through a wireless means, e.g. a receiver/transmitter component 306, for processing by the external component 324. By their nature, implantable sensors must have some mechanism for communicating sensed information from the sensor to a reader, which may be human or machine, outside the body. Since it is impractical to implant a physical connection between the sensor and the external reader, alternative means for generating a readable signal external the body is provided. Suitable means for generating a readable signal external the body include, without limitation, radiographically visible signals, magnetic flux signals, chemical signals, chemifluorescent signals, and/or electromagnetic signals. In a specific embodiment, radio frequency means can be used for wireless communication between sensor and an external device.

Now referring to the extravascular component 324, it may have a transceiver component 316 for bidirectional communication 312 and 314 with intravascular component 310. It may also have a data processing component 318 for interpreting the presented data and comparing these to preset or programmable thresholds, which include static or dependant variables, such as rates that change with time. For example, a threshold could be the maximum allowable change of the heart rate. Another example of a variable can be the energy consumption over time. The data processing component may be a part of the external computer 320 or it may have a self-contained computing capability with its own memory and logic. Additionally, the extravascular component may have an external communication sub-component 322 for communicating with a programmer. It may also be used with the alerting system described in FIG. 6.

Sensing:

The description of parameter sensing is described in the monitoring section above and is incorporated herein by reference. While any of the sensing transducers adapted for use with the intravascular platform may be used, in the following, a signal amplifier and associated electronics that does not require a separate ground is described. The rationale for the signal amplifier is that in an implanted system, an additional ground line will only see common mode especially when the signal pair is either from a coaxial or a twisted pair.

In an exemplary case of electrical sensing and amplifying of physiological signals is shown in FIG. 8A, wherein, the amplifier 332 has competing electromagnetic signal sources that may cause deterioration of signal quality performance. Established methods include the use of common mode rejecting amplifier designs, which reference the leads of a signal pair 328 to a reference, a real or virtual ground. When the signals have amplitudes in the range of few tens of mV, the performance of such solutions is good, as the operating voltage range is many orders of magnitude greater than the supplied signal, thereby allowing for large “common mode” signals to be superimposed on the signal of interest.

If the main signal leads, providing Va and Vb are contained within a space or volume with noise sources external to that volume as would be the case in an implanted system, the reference or ground lead may be removed with a concomitant performance improvement of the system as shown in FIG. 8B. By removing the external reference or ground, the signal lines maybe exposed to common mode noise. However, without a path to reference this noise, a common mode circuit cannot be formed resulting in the original signals to be presented to the amplifier. By arranging the two signal leads in a twisted pair fashion 348, it can be ensured that input conductor impedance for the signal amplifier 350 is equal for both the leads with equal noise exposure.

Noise voltage 342 can still be injected within each individual conductor and present an unbalanced noise component to the amplifier 350 where it will be amplified and spoil the original signal. Depending on location and application, the contributions of unbalanced noise must be considered before choosing this method.

In the FIG. 7B, Ze 354 is a virtual component, representing the impedance to the enclosing volume 346. When the enclosing volume has low impedance to the noise generator, it will form an electrostatic shield, whose effectiveness increases proportionally to the conductivity of that environment.

Detection and Classification:

FIGS. 9, 10, 11 and 12 schematically illustrate functional aspects of the detection system enabled by the intravascular platform. The detection can be done during the signal acquisition, post signal acquisition or during both.

In a preferred embodiment, the signal detector comprises a signal transition detector shown in FIGS. 10 and 12 followed by an event classifier shown in FIG. 13. The signal transition detector 370 includes a comparator 382, which is presented with the signal V(t) and a time shifted copy of the signal V(t+Δt) 350, wherein the comparator identifies features in the signal that are distinguished by having a local zero derivative representing the change of direction of the signal amplitude. The output consists of digital pulses 354 of varying width as shown in FIG. 9.

The signal detector can be implemented using a circuit using conventional operational amplifiers for frequencies less than 200 Hz. However, for higher frequencies, comparator operational amplifiers are preferred. In any case, the output of the circuit is independent of the input signal. The method is sensitive to the time delay value 352, which will separate the signals in time. There are a number of conditions to consider in choosing the time delay value 352. It should prevent setting off events from small random noise amplitudes. It could be set to exclude certain portions of the cardiac signal time sequence. For example, when a good QRS signal is detected, a larger delay can be chosen.

In FIGS. 11 and 12, it can be seen that the waveforms and the amplitude transition threshold (deadband) 366 needed to trip the comparator 382 is a function of the associated hysteresis of the circuit, and the open loop gain of the comparator. The hysteresis amount ΔV is a function of the deadband 366 that can be chosen based on the component selection. The resistors R₁ 374 and R₂ 378 are chosen such that their ratio approximates the desired hysteresis. The components R378 and C380 determine the time constant of the delay. The threshold required to switch states is a function of the gain and slew rate of the comparator 382 or operational amplifier at the frequencies of interest. Typically the gain roll off rate is 20 dB per decade from 1 kHz onward. With such a roll off point, a 105 dB gain at 1 kHz reduces to a gain of 65 dB at 100 kHz. The slew rate is the maximum rate by which the output 384 can change state. For example, a IV/msec slew rate would require at least 5 ms to go from 0 to 5 volts, regardless how hard the input is being overdriven.

The output 384 of the detector is shown in FIG. 9 and it is a transformed signal which is discrete. It should be noted that this technique is immune to the variations in the input continuous signal unlike traditional methods. The discrete signal can be used advantageously for signal classification as described below.

In FIG. 13, signal classification is described. The signal classifier 385 has means 386 to access to the continuous analog biological signal which is transformed at block 388 into discrete signal by the signal detector described in FIGS. 9, 10, 11 and 12. The discrete signal is used to detecting the features of interest by a feature detection means 392. The feature detection means 392 compares the transformed signal to a previously determined rules/features knowledgebase. Based on previous determined features and the conditions at which a specific set of rules are applied, signals are put under different classes. Note that classifier 394 can also be linked to the knowledgebase 390 through a link 402 which may save results or expert overrides for the future references.

For the purposes of reporting on paper or in an electronic medical record, analog signal may be digitized and displayed or reported using the means 396 with the classified information superimposed via linkage 400. Finally the displayed signal can be stored and/or printed at block 398 for future reference.

In the case of fibrillation detection, the signal detector further comprises a pulse counter that counts the number of pulses for a preset time period. If the current signal corresponds to the normal heart beat, the pulse counter would register a count in a predetermined normal range since the normal biological signals have transition changes at a relatively low rate. In the event of a fibrillation, the count would be dramatically different and much higher than the normal rate and this increased count would be advantageously used to determine a defibrillation event. The physiological noise will also have relatively high counts but these counts would not add up to a sustained large number and thus can be differentiated from a fibrillation event. Unlike the traditional techniques, this method is robust and immune to signal filter degradations and provides a greatly improved event detection and classification.

As another example, the signal detector can be used to determine the heart rate and use this information in an algorithm for pacing a patient's heart. The heart rate detection is based on the number of transitions counted over a prespecified time interval. If the heart rate goes out of range for a predefined time and the frequency of the transitions remain in the non-fibrillation range, cardiac pacing can be initiated to pace the patient's heart.

In another application, when a discrete transition signal has been detected, it can be advantageously used to determine slope and slope duration analysis or any other methods of characterizing the QRS of an ECG signal.

Moreover, instead of the ECG, other signals may be used to utilize the disclosed concept. These may include blood pressure, vasomotor tone, electromyography (EMG), electrodermography, electroneuography, electro-oculography (EOG), electroretinography used (ERG), electronystagmography (ENG), video-oculography (VOG), infrared oculography (IROG), auditory evoked potentials (AEP), visual-evoked potentials (VEP), all kinds of Doppler signal, etc.

Treatment:

The treatment system uses the information detected by the detection and classification system and treats the patient condition. The treatment can be imparted via electrical, mechanical, thermal, chemical or drug stimulation. In one embodiment, the treatment can be long term stimulation for tissue repair. In another embodiment the treatment is a periodic stimulation for chronic pain relief. In another example, the treatment is short term stimulation for defibrillating a fibrillating heart. In one embodiment, the treatment can be achieved by stimulating a vessel to treat a medical condition. In another embodiment, the treatment is achieved by stimulating a nerve indirectly through a vessel stimulation to treat a medical condition.

Certain changes to the existing means for the treatment are necessary before incorporating them in the intravascular framework. In the following, changes to the lead and the stimulation waveforms are described.

FIG. 14A is a schematic of circuitry of a traditional lead and the electrical equivalent of the tissue to be stimulated. The lead 403 is typically characterized by a high series resistance in the range of 200 to 1,500 ohms. The nominal value of this series resistance 404 is 1,200 ohms. The reason for this high resistance is to limit the current from a capacitor 410 (e.g., 7 μF). In order to represent the tissue resistance at DC, a resistance 412 is added in parallel to the capacitor 410. The electrical equivalent of the tissue to be stimulated is modeled as an equivalent resistance 406 and an equivalent capacitance 408 in parallel with the capacitance 410. The equivalent resistance is derived from a concatenated lattice comprising a series resistance and a capacitor connected to the commons.

FIG. 14B describes the present modification wherein the high resistance lead is replaced by an ultra low resistance lead 413 in a wireless intravascular platform. This is shown as a dotted component schematically. Preferably the resistance 414 of the lead is designed to be less than five Ohms. In order to represent the tissue resistance at DC, a resistance 422 is added in parallel to the capacitor 420. The current design makes the RC time constant smaller and consequently speeds up the rise time. This will be described next.

The stimulation waveform is generated using a computer program in the main computer of the intravascular platform. FIG. 15 describes a traditional pulse 424 that is characterized by a pulse of nominal amplitude that is “on” for a nominal duration (0.4 ms-2.0 ms). The area under the waveform is denoted by “N.”

FIG. 16 describes one embodiment of a composite pacing waveform diagram which is characterized by a first portion 430 consisting of a fast changing (4V/10 μs), short duration (0.05-0.2 ms), high amplitude (>3 times the nominal voltage) pulse that is followed by a second portion 432 consisting of a longer duration, pulse with an amplitude less than the nominal amplitude. The total duration of the pulse is less than the nominal duration of the traditional pulse. The total area under the first portion and the second portion is denoted by “C₁.” Note that area C₁ is less than the area N. Further note that the efficiency is gained by expending less overall energy and the clinical efficacy is gained by reducing the stimulation threshold for most of the duration of the pulse.

FIG. 17 describes another embodiment of a composite pacing waveform diagram which is characterized by a first portion 440 consisting of a fast changing (4V/10 μs), short duration (0.05-0.2 ms), high amplitude (>3 times the nominal voltage) pulse that is followed by a second portion 442 consisting of a longer duration, negative voltage pulse with an absolute amplitude that is less than the nominal amplitude. The total area under the first portion and the second portion is denoted by “C₂.” Again note that area C₂ is less than the area N. Further note that the efficiency is gained by expending even less overall energy and the clinical efficacy is gained by reducing the stimulation threshold for most of the duration of the pulse.

Getting back to alternative forms of stimulation, the stimulation treatment may be provided by stimulating a vessel indirectly through another vessel stimulation to treat a medical condition. FIG. 18 schematically illustrates functional aspects of this type of treatment system enabled by the intravascular platform.

In accordance with an exemplary method of this invention, one can utilize a system of RF energy transfer 452 from the extravascular signal generator and transmitter means 450 to the vascular transceiver 456 by use of wired or wireless means. Once the energy is received in the venous system it may be transmitted by means of more conventional wires 454 within the venous system. Such hardware is, in general, not a major issue in the venous aspect of the vasculature. However, such hardware can be problematic in the arterial aspect of the vasculature since it can potentially cause arterial occlusion or obstruction to arterial blood supply. RF energy is received into the venous vasculature as described before. The energy is then transferred to the arterial vessel 458 by means of inductive coupling 460 using, for example, parallel coils. The coil in the venous system is powered via the transceiver wired to a second site of interest. At this site, the artery is in close proximity contains a stent like coil 462 capable of receiving an induced current. This stent is not hardwired, but is placed similar to typical stents used to keep arteries open. However in this application the stent may have different configurations. In one embodiment, it may be an electrical solenoid type device. In another embodiment, it may be a spiral or a combination of spirals and solenoids. Any of these configurations are capable of converting the induced energy from the venous inductor for the purpose of stimulating receptors in the wall of the artery and/or for monitoring parameters such as pressure, blood flow and other physiologic parameters or chemical parameters in the artery. The arterial transceiver is also able to send such data either to the nearby transceiver in the venous system for relaying to the external receiver as shown or directly without a relay (not shown). In one embodiment, the stimulator coil 462 in the arterial system can stimulate a nerve 464 through energy transfer 468.

Device Control:

The intravascular platform can be conveniently used to control a device. In one embodiment, the platform can deliver scalable wireless energy to one or more applications. In one example, the wireless energy can be used for powering a localized drug delivery system. As another example, the wireless energy can be used to control localized tissue ablation. In yet another example, the wireless energy may be used to control heart augmentation devices.

Referring to FIG. 20, the power source and the extravascular transceiver 480 can supply energy and control signals 482 through a transceiver/electronics system 484 to power an implanted sensing and/or monitoring system 486 that has been described in detail earlier.

Referring to FIG. 21, the power source and the extravascular transceiver 490 can supply energy and control signals 492 through a transceiver/electronics system 494 to power an implanted sensing and stimulation system 496 that has been described in detail earlier.

Referring to FIG. 22, the power source and the extravascular transceiver 500 can supply energy 502 through a transceiver/electronics system 504 to control an implanted sensing and stimulation system 506 that has been described in detail earlier.

Referring to FIG. 23, the power source and the extravascular transceiver 510 can supply energy 512 through a transceiver/electronics system 514 to control an implanted support system 516. For example, an implanted support system can be a cardiac augmentation device.

Combination/Hybrid:

Multi-functional hybrid platform shown in the FIG. 19 can stimulate different sites using different site-specific electrodes and associated electronics. The power source and transceiver 470 can transfer energy and/or control data 472. The system further has integrated detection/sensing module such as 474 and 476 for one or more normal or abnormal medical conditions of one or more physiological processes and/or organ systems. One or more of multiple transceiver coils used for energy/data transfer and/or sensing/stimulation are programmatically selectable for the specific medical condition. The stimulation coil can be an energy relay coil to power a plurality of organ, tissue, fiber, molecular, and drug functions. The transmitter can send specific coded signals to select a specifically chosen receiver at a chosen site. In one embodiment, the hybrid system can perform multi-purpose cardiac stimulation that may include at least two treatments selected from a set comprising cardiac pacing and atrial fibrillation treatment and ventricular fibrillation treatment. In another embodiment, the hybrid system is applied to perform non-cardiac applications including brain stimulation, vagal nerve stimulation, spine stimulation, GERD treatment stimulation, GI tract stimulation, stimulation to treat obstructive airway disorders such as apnea, therapeutic stimulation of muscles, nervous tissue or organs, skeletal muscle stimulation, endotracheal stimulation, pelvic floor stimulation, sacral nerve stimulation, pancreatic stimulation, chronic constipation treatment, and prosthetic lamina stimulation for healing bone tissue. In another embodiment, the hybrid system can perform cardiac and non-cardiac stimulation.

With the hybrid platform it is possible to use any combination of features that are enabled by the system programmatically. It is also possible to disable any desired feature programmatically as well.

Temporal Attributes of Wireless Intravascular Platform

In many applications, the intravascular wireless platform may be configured for various temporal attributes. In one example application, the wireless intravascular platform can be configured for continuous operation of, for example, monitoring or sensing. In another example, the platform may be configured for intermittent operation of, for example, electrical stimulation. This operation may be guided by a physiological need as in an exemplary case of cardiac stimulation of CHF patients whose heart rate fell below a predetermined threshold. In another example, the platform may be configured for a triggered operation. In this example, one may use intravascular or external ECG to trigger physiological data sensing and/or monitoring. In another example application, the platform may be operated by an interrupt. In this example, the platform may switch from the regular mode of operation to a time critical or life critical operation that requires immediate attention. Defibrillation therapy is an example of this case.

In some example applications, the platform may be interrogated to communicate with the external devices. The communication may be continuous, interval-based, interrupt driven, event driven or data driven. The communication may include by way of example, unprocessed or processed physiological data, alerts to the patient, or a caregiver, device service data, device identification data. The mode of communication may be audio, visual, text, or graphics. The communication may be local or remote. It may be automated, operator assisted or patient driven.

The foregoing description was primarily directed to a preferred embodiments of the invention. Although some attention was given to alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.

Claims

1. An intravascular system implantable in vascular of an animal for providing electrical stimulation of tissue to deal with a clinical condition of the animal, the intravascular system comprising: an implantable control module for controlling the electrical stimulation and producing a desired digital waveform having an envelope defined as a function of an attribute;an implantable intravascular sensing module sensing at least one parameter of interest for a purpose to deal with the clinical condition; andan intravascular stimulation module for electrically stimulating the tissue with a output waveform that is substantially similar to the desired digital waveform produced by the implantable control module; anda power supply for furnishing energy to the implantable control module, the implantable intravascular sensing module, and the intravascular stimulation module.

2. The intravascular system as recited in claim 1 wherein the power supply is an implantable non-rechargeable battery.

3. The intravascular system as recited in claim 1 wherein the power supply is an implantable rechargeable battery.

4. The intravascular system as recited in claim 1 wherein the power supply is a wireless energy source using a near-field resonant, inductive coupling to implantable components.

5. The intravascular system as recited in claim 1 wherein the at least one parameter of interest is related to a characteristic selected from a group consisting of electrical characteristics, mechanical characteristics, chemical characteristics, temperature, blood flow, blood pressure, blood volume, blood viscosity, electrolyte level, reference location, glucose level, urea level, carbon dioxide level, oxygen concentration, drug delivery, and drug level.

6. The intravascular system as recited in claim 1 wherein the purpose of electrical stimulation is selected from a group consisting of medical therapy, medical treatment, therapy monitoring, and detection or sensing of evoked responses to electrical stimulation of the tissue.

7. The intravascular system as recited in claim 1 wherein the clinical condition dealt with is selected from a group consisting of irregular cardiac rhythms, slow or fast cardiac rhythms, infarct repair, ischemia detection, chronic heart failure resynchronization, tachycardia stimulation/cardiac stimulation, seizure prevention, seizure warning, obsessive compulsive disorder, spine problem, GERD, neuronal disorder, gastro-intestinal disorder, obstructive airway disorder, skeletal muscle problem, endo tracheal problem, pelvic floor problem, sacral nerve problem, depression, obesity, pain relief, nerve damage, pancreatic disorder, chronic constipation problem, and internal wounds.

8. The intravascular system as recited in claim 1 wherein the intravascular stimulation module is adapted to electrically stimulate tissue of an animal organ selected from a group consisting of brain, heart, esophagus, stomach, kidney, ear, eye, lung, uterus, prostate, blood, spine, bladder, pancreas, colon, and nervous system.

9. The intravascular system as recited in claim 1 wherein the output waveform is at least one of intermittent, interrupt driven, and event driven.

10. The intravascular system as recited in claim 1 wherein the attribute is one of a physiological characteristic of the animal, received telemetry signal, and a preprogrammed clinical algorithm.

11. A wireless intravascular system implantable in vascular of an animal for providing electrical stimulation of tissue to deal with a clinical condition of the animal, the intravascular system comprising: an implantable control module for controlling operation of the wireless intravascular system and producing a desired digital waveform having an envelope that is a function of an attribute;an implantable intravascular sensing module sensing at least one parameter of interest for a purpose to deal with the clinical condition; andan intravascular stimulation module for electrically stimulating the tissue with a output waveform that is substantially similar to the desired digital waveform produced by the implantable control module; anda power supply module utilizing a near-field resonant, inductive coupling to convey energy to the implantable control module, the implantable intravascular sensing module, and the intravascular stimulation module.

12. The wireless intravascular system as recited in claim 11 wherein the at least one parameter of interest is related to a characteristic selected from a group consisting of temperature, blood pressure, blood volume, blood flow, blood viscosity, electrical characteristics, mechanical characteristics, chemical characteristics, electrolyte level, reference location, glucose level, urea level, carbon dioxide level, oxygen concentration, carbon dioxide level, drug delivery, and drug level.

13. The wireless intravascular system as recited in claim 11 wherein the purpose of electrical stimulation is selected from a group consisting of medical therapy, medical treatment, therapy monitoring, and detection or sensing of evoked responses to electrical stimulation of the tissue.

14. The wireless intravascular system as recited in claim 11 wherein the clinical condition dealt with is selected from a group consisting of irregular cardiac rhythms, slow or fast cardiac rhythms, infarct repair, ischemia detection, tachycardia stimulation/cardiac stimulation, chronic heart failure resynchronization, seizure prevention, seizure warning, obsessive compulsive disorder, spine problem, GERD, neuronal disorder, gastrointestinal disorder, obstructive airway disorder, skeletal muscle problem, endo tracheal problem, pelvic floor problem, sacral nerve problem, depression, obesity, pain relief, nerve damage, pancreatic disorder, chronic constipation problem, and internal wounds.

15. The wireless intravascular system as recited in claim 11 wherein the intravascular stimulation module is adapted to electrically stimulate tissue of an animal organ selected from a group consisting of brain, heart, esophagus, stomach, kidney, ear, eye, lung, uterus, prostate, blood, spine, bladder, pancreas, colon, and nervous system.

16. The wireless intravascular system as recited in claim 11 wherein the output waveform is at least one of intermittent, interrupt driven, and event driven.

17. The intravascular system as recited in claim 11 wherein the attribute is one of a physiological characteristic of the animal, received telemetry signal, and a preprogrammed clinical algorithm.

18. An intravascular implantable system for providing electrical stimulation of a tissue in side an animal for to deal with a clinical condition, the intravascular implantable system comprising: an implantable control module for controlling the electrical stimulation and producing desired digital waveforms that have envelopes with predetermined attributes;an implantable intravascular sensing module sensing at least one parameter of interest for a purpose of dealing with the clinical condition; andan intravascular stimulation module electrically stimulating the tissue with a output waveform that is substantially similar to the desired digital waveform produced by the implantable control module; anda power supply module comprising a rechargeable energy source with a near-field resonant, inductive coupling for supplying energy to the implantable control module, the implantable intravascular sensing module, and the intravascular stimulation module.

19. The intravascular implantable system as recited in claim 18 wherein the at least one parameter of interest is related to a characteristic selected from a group consisting of temperature, blood pressure, blood volume, blood flow, blood viscosity, electrical characteristics, mechanical characteristics, chemical characteristics, electrolyte level, reference location, glucose level, urea level, carbon dioxide level, oxygen concentration, carbon dioxide level, drug delivery, and drug level.

20. The intravascular implantable system as recited in claim 18 wherein the purpose of electrical stimulation is selected from a group consisting of medical therapy, medical treatment, therapy monitoring, and detection or sensing of evoked responses to electrical stimulation of the tissue.

21. The intravascular implantable system as recited in claim 18 wherein the clinical condition dealt with is selected from a group consisting of irregular cardiac rhythms, slow or fast cardiac rhythms, infarct repair, ischemia detection, tachycardia stimulation/cardiac stimulation, chronic heart failure resynchronization, seizure prevention, seizure warning, obsessive compulsive disorder, spine problem, GERD, neuronal disorder, gastrointestinal disorder, obstructive airway disorder, skeletal muscle problem, endotracheal problem, pelvic floor problem, sacral nerve problem, depression, obesity, pain relief, nerve damage, pancreatic disorder, chronic constipation problem, and internal wounds.

22. The intravascular implantable system as recited in claim 18 wherein the intravascular stimulation module is adapted to electrically stimulate tissue of an animal organ selected from a group consisting of brain, heart, esophagus, stomach, kidney, ear, eye, lung, uterus, prostate, blood, spine, bladder, pancreas, colon, and nervous system.

23. The intravascular implantable system as recited in claim 18 wherein the output waveform is at least one of intermittent, interrupt driven, and event driven.

24. The intravascular system as recited in claim 18 wherein the attribute is one of a physiological characteristic of the animal, received telemetry signal, and a preprogrammed clinical algorithm.