Patent Description:
In a conventional diagnostic catheter, the weak biopotential signals picked up by the right electrodes in the distal tip are amplified in external equipment that is separated from the electrodes by several meters of wiring. This wiring is vulnerable to noise pick up from <NUM> power mains and higher frequency interference from operating room equipment. As a result, signals such as complex fractionated atrial electrograms with amplitudes in the <NUM>'s of µV are often buried in the noise.

Existing intracardiac recording techniques, while they have served the clinician and basic scientists reasonably well over the past three to four decades, suffer from several inherent limitations. By the very nature of utilizing electrodes connected by long cables to a distant differential amplifier, these systems are subject to line "noise," ambient EMI, cable motion artifacts, and faulty connections.

Local signals are subject to recording of far-field signals, which at times render the interpretation of complex, rapid arrhythmias very difficult, if not impossible. The conflation of far-field and signals of real interest, such as pulmonary vein fiber potentials, accessory pathway signals, and slow pathway potentials, can sometimes be the cause of failed ablations. The ability to record local electric activity with great precision and to the exclusion of far-field signals would be of paramount importance.

Current recording systems frequently cannot differentiate low amplitude, high-frequency signals from background noise. Extremely low amplitude signals, such as those generated during slow conduction within a myocardial scar, are frequently missed or lost in the background noise when amplifier gain is made sufficiently high to attempt to record such signals.

Continuous, low amplitude, fractionated high-frequency signals such as those frequently seen in the atria of patients with chronic atrial fibrillation, cannot be further characterized using existing recording technologies. These signals may contain important biologic and electrophysiologic information. For example, these signals may represent important areas of scarring that are responsible for formation of rotors. Alternatively, they may be manifesting discharges from contiguous epicardial parasympathetic ganglionated plexi.

In one application, such as in Renal Denervation, variabilities in human microanatomy of renal nerve distribution and density of nerve endings from patient to patient mean that we cannot take a "cookie cutter" approach to circumferential ablation sites. Variability in neuron function in type and size, from large to small means that we cannot only ablate the larger regular-discharging neuron sites but must also target the smaller irreg tonal and can drive signaling even when the large sites have been successfully ablated.

Mapping of the renal artery allows for a precise identification of renal nerve location and size. Location data can be used to identify precisely where to ablate, while size information can be used to discern neuron types (regular, irregular, and non-spontaneous). This can lead to greater efficacy and a reduced need for serial ablations if the first is ineffective.

Another such application is in electrophysiological studies for identifying different types of arrhythmia. Electrophysiology studies are performed by measuring small signals from electrodes placed in the patient s heart in a sometimes very noisy environment. As currently practiced, signal detection in the electrophysiological Lab is subject to external noise from pick-up during the travel of the signal from the catheter tip to the amplifier located several feet away. Signal processing at the multichannel recorder can subject small signals of interest to degradation when appropriately amplified, such that important microvolt-sized signals are lost when noise is filtered out.

Fractionation potentials recorded in scarred myocardial tissue, which serve as ablation targets, as well as pulmonary vein potentials and accessory pathway potentials, need to be accurately characterized. Barbara Hubbard, in the text "The World According to Wavelets", expresses the fundamental problem of filtering as a method for smoothing the wave characteristics employing low pass and high pass filtering, and the obvious problem of separating the noise component from the native signal, which is the inability of the system to identify which is which. If we know that a signal is smooth, i.e. changing slowly , and that the noise is fluctuating rapidly, we can filter out noise by averaging adjacent data to climinate fluctuations while preserving the trend. Noise can also be reduced by filtering out high frequencies. For smooth signals, which change relatively slowly and therefore are mostly lower frequency, this will not blur the signal too much. Many interesting signals are not smooth; they contain high-frequency peaks. Eliminating all high frequencies mutilates the message, "cutting the daisies along with the weeds," in the words of Victor Wicker Hauser of Washington University in St. Louis, adequately expresses the main drawback of postprocessing such signals.

A prior art catheter is disclosed in <CIT>.

The invention is best summarized by the claims.

The optically coupled catheter of the illustrated embodiments can be used in any field of medical diagnosis or therapy and in particular has specific application to electrophysiology, renal denervation, neuromodulation, nerve ending measurements in the central nervous system (CNS), and for psychiatric therapy of patients with deep depression or manic depressive state where medicating agents are not effective. A special case is the use of such sensing modality in epileptic seizure, where the electrodes with such resolutions can augment the resolution of the focal point insertion of neuromodulating implantable electrodes where electrical potential at the site averts the epileptic event prior to its occurrence.

The illustrated embodiment is an optical catheter system which is scanner and magnetic resonance imaging (MRI) compatible. It is characterized by a highly flexible catheter without the use of any shielded wires in the catheter cable. The catheter system is totally immune to any radio frequency (RF) or electromagnetic noise or interference. The disclosure can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals.

The disclosure and its various embodiments can now be better understood by turning to the following detailed description of the preferred embodiments which are presented as illustrated examples of the embodiments defined in the claims. It is expressly understood that the embodiments as defined by the claims may be broader than the illustrated embodiments described below.

<FIG> is a block diagram of illustrating an impedance catheter system <NUM> using local amplifiers <NUM> according to one of the illustrated embodiments of the invention. A catheter <NUM> is coupled via a catheter cable <NUM>, which includes an optical fiber <NUM> to an optical interface <NUM>. Cable <NUM> and optical fiber <NUM>, which may be several meters long, is coupled to optical interface <NUM>, which in turn is coupled to a personal computer <NUM> or other data processor or control device or system through a conventional universal serial bus (USB). Optical interface <NUM> provides power to catheter <NUM> and serves to handle data flow to and from catheter <NUM>. A laser <NUM> is included in optical interface <NUM> and is controlled by a digital signal processor (DSP) <NUM>. For example, a 1W <NUM> Titanium-Sapphire laser or laser diode with about 50mW to 150MW optical output may be used. Any electrical control signals from computer <NUM> are communicated through DSP <NUM> to laser <NUM>, where they are output as optical or photonic signals, and are coupled into optical fiber <NUM>. Similarly, photonic data on optical fiber <NUM> input into optical interface <NUM> is received by photodiode <NUM> and converted into an electrical data signal communicated to DSP <NUM> and hence to computer <NUM>. Dichroic mirror <NUM> diverts a portion of the output of laser <NUM> to photodiode <NUM> for feedback control of the laser level.

The transmitted photonic signals from optical interface <NUM> is communicated through catheter cable <NUM> to emitting end <NUM> of optical fiber <NUM> and are directed into a GaN LED (Philips Lumileds Luxeon Z) or an InGaN/GaN ligh emitting diode (LED) and photodetector (PD) <NUM>. According to the direction of bias applied to LED/PD <NUM>, it operates either to receive a photonic signal and convert it into an electrical replica when biased as a photodiode or to generate a photonic signal in response to an electrical input when biased as an LED. A semiconductor such as InGaN/GaN with multiple quantum well structure commonly used for light emitting diodes can be employed for dual functions of optoelectronics devices exhibiting photodetector properties in under variable load conditions (bias). The principle of such device is noted by the fact that Optical emission resulting from <NUM> selective photoexcitation of carriers in the GaInN/GaN quantum well (QW) active region of a light-emitting diode, which reveals two recombination channels. The first recombination channel is the recombination of photoexcited carriers in the GaInN QWs. The second recombination channel is formed by carriers that leak out of the GalnN QW active region, which in turn self-bias the device in forward direction, and thereby induce a forward current, and subsequently recombine in the GalnN active region in a spatially distributed manner. The results indicate dynamic carrier transport involving active, confinement, and contact regions of the device. Thus, one can easily integrate photodetectors with LEDs using the same epi-structure to realize a GaN-based optoelectronic integrated circuit (OEIC). And <NPL>).

LED/PD <NUM> is coupled to light application specific integrated circuit (ASIC) <NUM>, which signal conditions and communicates a plurality of signals on serial peripheral interface (SPI) bus <NUM> to a plurality of amplifier ASIC's <NUM>, each of which are coupled to an electrode <NUM>. The plurality of MOSFET electrodes <NUM> together with tip ground electrode <NUM> are the sensing points of catheter <NUM>, similar to the MOSFET electrodes described in greater detail in Shachar, et. , "Apparatus for magnetically deployable catheter with MOSFET sensor and method for mapping and ablation", <CIT> incorporated herein by reference as if set out in its entirety. Sensed biopotentials from MOSFET electrodes <NUM> are locally amplified by amplifier ASICs <NUM> and communicated via bus <NUM> into light ASIC <NUM> to be multiplexed out to LED/PD <NUM> and communicated as multiplexed photonic signals on optical fiber <NUM>.

<FIG> is a block diagram of the components in the catheter tip of <FIG> according to the illustrated embodiments of the invention. Light ASIC <NUM> includes a power and data module <NUM>, which converts the optical signal originating from laser <NUM> into both an electrical power signal for catheter <NUM> as well of control signals and output data signals. Module <NUM> converts electrical power from LED/PD <NUM> derived from pulsed light into continuous capacitive stored power stored on capacitor <NUM>. Module <NUM> is coupled to LED/PD <NUM> and controls the bias on to LED/PD <NUM> as well as bidirectionally communicating digital signals thereto and therefrom. Module <NUM> is coupled to the catheter ground via a coupling resistor <NUM> used to monitor any leakage current protection and to a temperature sensor <NUM> by which signal conditioning and compensation are provided for catheter <NUM>. PMU Module <NUM> is also bidirectionally coupled to DSP <NUM> by which a synchronizing clock signal is provided to amplifier ASICs <NUM> and through with data and control signals are bidirectionally communicated.

DSP <NUM> communicates with DSP <NUM> in amplifier ASIC <NUM>, which receives the data signal sensed by electrode <NUM> through an analog to digital converter (ADC) <NUM>. ADC <NUM> in turn is powered by module <NUM> through low dropout (LDO) voltage regulator <NUM> driving a reference voltage circuit <NUM> coupled to ADC <NUM>. ADC <NUM> receives the data signal from low pass filter (LPF) <NUM> driven by programmable gain amplifier (PGA) <NUM>. PGA <NUM> takes its input signal from high pass filter (HPF) <NUM> driven by a fixed gain instrumentation amplifier (IA) <NUM> (here a Texas Instrument or Analog Devices AD8235ACBZ-P7). Electrode <NUM> and tip ground electrode <NUM> are coupled to IA <NUM> through an electrostatic discharge protection circuit <NUM>. In the illustrated embodiment IA <NUM> has a fixed gain of <NUM> while PGA <NUM> is programmable from <NUM> - <NUM>, thus making a <NUM>- <NUM>µV sensed signal at electrode <NUM> can be programmable and appear as a <NUM> - <NUM> mV input signal to ADC <NUM>, if PGA <NUM> is given again of <NUM>. Similarly, a <NUM> - <NUM>,<NUM>µV sensed signal at electrode <NUM> can be scaled to appear as a <NUM> - <NUM> mV input signal to ADC <NUM> by programming PGA <NUM> with a gain between <NUM> to <NUM>; or a <NUM> - <NUM>,<NUM>µV sensed signal at electrode <NUM> appears as a <NUM> - <NUM> mV input signal to ADC <NUM> by programming PGA <NUM> with a gain between <NUM> to <NUM>. In this manner different electrode mput signal ranges are programmable and accommodated.

<FIG> is a block diagram of another embodiment of the components in the catheter tip of <FIG>, similar to the embodiment of <FIG>. In the embodiment of <FIG> light ASIC <NUM> and amplifier ASIC <NUM> have been combined into an integrated ASIC <NUM>. In integrated ASIC <NUM> includes a multiplexer (MUX) <NUM> coupled to a plurality of electrode channels <NUM>, one of which is shown in detail in <FIG>. Temperature sensor <NUM> is also provided as an input to MUX <NUM>. A sequencer circuit <NUM> is coupled between MUX <NUM> and DSP <NUM> bidirectionally coupled to module <NUM> to control the sequence of channels <NUM> sampled. A programmable gain control signal is generated by DSP <NUM> and coupled to PGA <NUM>. Data is provided by PGA <NUM> for each electrode <NUM> through MUX <NUM> to a low pass filter <NUM> to analog-to-digital converter <NUM> for communication to DSP <NUM>.

<FIG> is a schematic diagram illustrating the fabrication of the components in the catheter tip according to the illustrated embodiments of the invention in which the catheter system is included in a size <NUM>. French catheter or smaller. Optical fiber <NUM> in catheter cable <NUM> is coupled through end <NUM> to an aspherical lens <NUM> directing collimated light from optical fiber <NUM> into LED/DP <NUM>. LED/DP <NUM> is disposed adjacent to the proximate end of flexible printed circuit board (FPCB) <NUM> which extends through the body of catheter sheath <NUM>. In the embodiment of <FIG> a microcontrollet (MCU) <NUM> with a built-in analog-to-digital converter is disposed on one side of FPCB <NUM> and an inverting amplifier circuit (INV) <NUM> is disposed on the opposing side of the FPCB <NUM>. INV <NUM> (here a Diodes 74AUP2G06) is a low-power dual inverter with open-drain output. It provides two inverting buffers with open-drain output. The output of the device is an open drain and can be connected to other open-drain outputs to implement active-LOW wired-OR or active-HIGH wired-AND functions. A Schmitt-trigger action at all inputs makes the circuit tolerant to slower input rise and fall times across the entire VCC range from <NUM> V to <NUM> V. INV <NUM> ensures a very low static and dynamic power consumption across the entire VCC range from <NUM> V to <NUM> V. It is fully specified for partial power-down applications using IOFF. The IOFF circuitry disables the output, preventing the damaging backflow current through the device when it is powered down. The stacked height of MCU <NUM>, INV <NUM> and FPCB <NUM> is about <NUM> and the width of FPCB <NUM> is about <NUM>, the width of MCU <NUM> and INV <NUM> being less. Also coupled to MCU <NUM> on FPCB <NUM> is a bandpass filter <NUM> and thence to 1A <NUM>. Disposed on the opposing side of FPCB <NUM> from IA <NUM> is a multiplexer (MUX) <NUM>. MUX <NUM> is coupled to the plurality of MOSFET electrodes <NUM> on catheter <NUM> and to tip ground electrode <NUM>.

<FIG> is a block diagram of yet another embodiment of the components in the catheter tip of <FIG> in which MUX <NUM> is coupled to tip ground electrode <NUM> and through a plurality of ESD circuits <NUM> to a corresponding plurality of MOSFET electrodes <NUM>. IA <NUM> and bandpass filter <NUM> are then serially coupled between MUX <NUM> and the built-in ADC within MCU <NUM>. MCU <NUM> generates a control signal to MUX <NUM> which controls the sequencing of the multiplexed data input signals from MOSFET electrodes <NUM>. Temperature sensor <NUM> in turn is coupled to MCU <NUM> as is resistor <NUM>. The catheter system <NUM> of <FIG> is fabricated in one embodiment as shown in <FIG>, similar to the embodiment of <FIG>. In the embodiment as depicted in <FIG>, IA <NUM>, BPF <NUM>, and MCU <NUM> are mounted on and coupled to the top surface of FPCB <NUM> as top components <NUM> with MUX <NUM>, capacitor <NUM> and module <NUM> are mounted on and coupled to the bottom surface of FPCB <NUM> as bottom components <NUM>. LED/PD <NUM> and lens <NUM> are adjacent to and midline with FPCB <NUM> with optical fiber <NUM>. As shown in the perpendicular cross sectional view of <FIG>, as seen through section lines <NUM> - <NUM> of <FIG>, top components <NUM> and bottom components <NUM> again present a stacking height with FPCB <NUM> of <NUM> or less with a width defined by the width of FPCB <NUM>, which can be selected as <NUM> or less. FPCB is electrically coupled by wiring to catheter <NUM> for grounding purposes. <FIG> is a block diagram of the embodiments whereby photonic power and data transmitted optically employing an Indium Gallium Nitride (InGaN) bidirectional LED. <FIG> further shows the two sections of the catheter <NUM> whereby the catheter is schematically divided into a proximal section <NUM> represented by the handle <NUM> on <FIG> and a distal section of the catheter <NUM> containing the electrodes and the photonic machinery forming the biosensing portion of the catheter.

<FIG> is a schematic representation of the principle of operation of the photodiode and the laser forming the photonic scheme employed by the catheter for the detection of the biopotential. The schematic forming the circuit of photonic power to the electronics where the laser <NUM> provides coherent light <NUM> (<NUM>) through the dichroic mirror <NUM> and the optical fiber <NUM> to the LED/PD <NUM>. The LED/PD <NUM> also selectively generates an optical signal <NUM> (<NUM>) that returns through the optical fiber <NUM> to the dichroic mirror <NUM> where it is reflected to a photodiode <NUM>. Further circuit <NUM> included in MCU <NUM> is a variable load which enables modulation of the signal fonned by the blue InGaN LED/PD <NUM> to generate a data stream representing the biopotential detected by the electrodes <NUM>. The operation of the laser <NUM> and the blue InGaN LED/PD <NUM> where DC power <NUM> (<NUM>) is delivered to the catheter and where a return of a binary data stream to circuit <NUM> is further described by <FIG>.

<FIG> is a pair of graphs illustrating how an LED and a laser forming the photonic detection and power mechanism are employed in the detection and data transmission of biopotential measurement employing a catheter. The graph in the left portion of the figure is a representation of the laser and LED intensity as a function of time. The graph in the right portion of the figure is a representation of the LED current as a function of applied voltage.

<FIG> indicate two modes of operation in the photonic scheme which enables the bio-detection of potentials within biological tissue. Whereby Laser <NUM> shown in <FIG> generates a light beam transmitted through a dichroic mirror <NUM> and optical fiber <NUM> so that a continuous light source power signal <NUM> with a wave length of <NUM> is delivered the through LED/PD <NUM> to power the electronics of ASIC <NUM>. When reverse biased LED/PD <NUM> is generated by the variable load condition <NUM> and set by microcontroller <NUM>, the equivalent voltage potential measured at the biological species (Heart surface tissue or nerve ending) a data stream <NUM> with a wavelength of <NUM>, is emitted by employing the modulation of circuit <NUM> (photonic equivalent emission of the potential measured at the biological site), whereby a variable load, changes the intensity of the of light generated by LED/PD <NUM> to send a binary data stream. The use of bidirectional InGaN LED/PD <NUM> is possible by the employment of dichroic mirror <NUM> which splits the beam as well as the incorporation of a variable load which modulates the light intensity output by LED/PD <NUM>. Clocked pulsed power is delivered at <NUM> and clocked binary data is returned at <NUM> as shown in the left portion of <FIG> in a time-multiplexed fashion. The right portion of <FIG> graphically represents the relationship between the current/voltage curve <NUM> of LED/PD <NUM> and the variable load of circuit <NUM> to provide the binary states as represented in the left portion of <FIG>.

<FIG> is a side view of an assembled catheter system with a steerable tip. A catheter handle <NUM> includes optical interface <NUM>. Catheter cable <NUM> extends from handle <NUM> to the site of operation and terminates in catheter <NUM>. A conventional stylet is included in catheter cable <NUM> and is controlled from handle <NUM> for steering and maneuvering the location of the catheter distal end, thereby enabling contact with the targeted site within the confinement of the biological species desired, e.g. heart surface tissue or nerve ending and, optionally catheter <NUM>, to allow catheter <NUM> to be remotely steered from handle <NUM>.

<FIG> illustrate a possible application of employing the invention within the current art of electrophysiological studies. The figure illustrates the deployment of the catheter <NUM> into the right renal arterial tract, adjacent to renal vein <NUM>, for renal denervation (RDN), a minimally invasive procedure to treat resistant hypertension. The procedure uses radiofrequency ablation to burn the nerves in the renal arteries. This process causes a reduction in the nerve activity, which decreases blood pressure. The RDN protocol require a site- specific identification of renal artery <NUM>, renal ganglion <NUM>, and the electroanatomic location of arborized sympathetic renal nerve endings <NUM>, the nerve <NUM> is then ablated by the use of radiofrequency modality through the adventitia <NUM>, while correcting or modifying using local amplification of biopotentials sensed in the renal artery <NUM> of the left kidney <NUM>. Catheter <NUM> is disposed through abdominal aorta <NUM> carrying aorto-corneal ganglion <NUM> into renal artery <NUM> in the proximity of renal ganglion <NUM>. The use of the inventive device catheter <NUM> enable a proper definition of the location of the nerve ending and thereby will improve the diagnostic value of the current art of RDN.

<FIG> is perspective diagram illustrating the renal detail of the renal artery of <FIG> in relation to the tip of catheter <NUM> and the fact that the anatomical variability of the arborized sympathetic renal nerve endings <NUM> is human specific and cannot be assumed to be a generic map, most of RDN procedure fail. <FIG> is an illustration of a left kidney <NUM> where the nerves innervating the kidneys are either efferent or afferent nerves. The nerves innervating the kidneys are either efferent or afferent nerves <NUM> shown in <FIG>. The efferent nerves derive from the neuraxins, along the renal artery <NUM> and vein. The afferent renal nerves travel from the kidney toward the dorsal root ganglia <NUM> along the spinal cord. The efferent renal nerves are postganglionic, and the majority of these are adrenergic, i.e., they contain norepinephrine varicosities at their nerve terminals.

An important neurotransmitter role for norepinephrine is supported by the observations that decreasing renal sympathetic nerve activity to zero by chronic renal denervation reduced renal tissue nore concentration by ><NUM>%, conversely, increasing renal sympathetic nerve activity by renal sympathetic nerve stimulation increased norepinephrine concentration in renal venous blood. The signal characteristics of the efferent or the afferent nerves <NUM> is identified by the low noise high sampling rate ADC <NUM>, DSP <NUM> and PMU <NUM> in <FIG> forming a digital "snap shot" associated by the employment of the electronic scheme <NUM> and nerve ending-signal signature representation.

The example of clectro-anatomic cases, be it RDN in <FIG>, clectrophysiological study for arshythmia indicated by schematic <FIG>. or nerve ending variable anatomical placement of efferent or the afferent nerves shown in <FIG> are further illustrations of the needs for accurate mapping of electro-anatomical features where a proper diagnosis and spatial definition including a clear representation of the morphological characteristics of the signal(s) provides an important diagnostic information which in turn impact the therapeutic success of the medical interventional procedure i.e. RDN or EP study of arrhythmias. <FIG> further illustrates the incorporation of apparatus for facilitating guided delivery of a MOSFET mapping (and potentially), delivering RF energy for ablation via catheter <NUM> to innervated tissue and ganglia that contribute to renal sympathetic nerve activity in accordance with embodiments of the invention.

In another embodiment, the RF ablation catheter <NUM> is used cooperatively with an imaging system such as known the art for example, an impedance mapping apparatus by such as the St. Jude Medical ENSITE or magnetic localization system, as exemplified as CARTO by J&J BioSense Webster, which enables a catheter to locate target within anatomical context and by provide geometric coordinates of specific anatomical destination e.g. renal nerves This process of defining an anatomical site such as a renal plexus ganglion to effect a change of nerve signal or generally enhance a procedure, we generally classify as neuromodulation or a renal denervation. Specifically, where a surgical and/or electrical intervention deactivates the ability of the sympathetic nerve or its ganglia to influence the activity of the sympathetic autonomic nervous system to achieve a clinical outcome.

In another embodiment of the invention we improve the desired clinical outcome by employing the MOSFET sensor array of electrodes <NUM> within the catheter <NUM> in a stable position whereby the MOSFET sensor array of electrodes <NUM> registers a high bioelectrical potential and when an impedance sensor, which is software defined within the catheter's digital circuitry, indicates a contact with a specific impedance value, the catheter <NUM> is than activated to deliver energy with a set value of e.g. <NUM>-<NUM> watts of RF energy. <FIG> describes a MOSFET sensor array of electrodes <NUM> and its irrigated RF ablation catheter <NUM> configured for maintaining the catheter in a stable position and orientation as detailed using the embodiments noted by the referenced patent noted above and by delivenng the necessary energy to denervate the active site. The system and its methods provide the operator with the means to affect the modulation of nerve activity and achieve the desired goal of neuro-attenuation to achieve an optimal clinical goal.

The process described is governed by the use of the apparatus' ability to first provide an indication of position and orientation of the catheter <NUM> with constant impedance value indicating surface contact with the vessel lumen so as to be enable to deliver the necessary RF energy through the adventitia and where the ablating energy is transmitted to the renal nerve and the ganglia in an optimal and safe mode.

According to one embodiment, the irrigated ablation catheter <NUM> with its integrated MOSFET sensor array of electrodes <NUM> is delivered to a location within a patient's renal artery <NUM>. The MOSFET sensor array cameter <NUM> preferbly includes a mapping device, (not shown) such as EnSite Navix of St. Jude Medical or other mapping device such as CARTO produced by J&J BioSense Webster.

<FIG> is a perpendicular cross sectional view of the renal artery of <FIG> is a longitudinal cross sectional view of the renal artery of <FIG>, which illustrate the structure of renal artery <NUM>, namely showing the nerves <NUM> in the renal wall, the renal lumen <NUM>, the endothelium <NUM> providing the lining of renal artery <NUM>, the media layer <NUM> backing the endothelium <NUM>, the surrounding adventitia <NUM> and finally the encasing fat tissues <NUM>. The above anatomical details are an illustration of the complexity and variability of the anatomical sits, where biopotential activities must be distinguished, identified and recorded with fidelity so as to enable a therapeutic optimal result. This is the mainstay of the utility of the inventive steps of employing a local amplification and digitizing such distinct signal with fidelity and ohmic value that the current art can't deliver, due to the inherent signal-to-noise ratio (SNR) in the current architecture of electrodes processed at a distance.

<FIG> is a diagrammatic longitudinal side cross section of the left atrium of the heart <NUM> and where an clectrophysiological study employing an optical catheter <NUM> combined with a decapolar catheter <NUM> to identify electrical potential biosignals <NUM> within the left superior pulmonary vein <NUM>. With the use of the novel optical catheter, the SNR and far-field/near-field averaging customarily used by the current art is reduced substantially by recording the biopotential on the sites without averaging the signal and the fact that the native signal is digitized within the distal end of the catheter <NUM>, the measured output cannot be corrupted by any external noise and/or pickup by the long shaft of the catheter. <FIG> illustrates the sensing of an excitable cellular matrix typical for heart's muscle. The sensed biosignals <NUM> from the decapolar catheter <NUM> are depicted in graphic form to illustrate an electrophysiological study, where a physical placement of multiple catheters in the left atrium to sense and afterword ablate the desired site(s) in order to correct an arrhythmia, (e.g. such as Afib). The figure illustrates the case where multiple electrodes catheter <NUM> will display different biopotentials and unless we distinguish them and record them locally, the current art technology averages their values and can't distinguish between far and near field results.

Additionally, <FIG> is a graphical representation of a ganglionic waveform indicating the ability to distinguish characteristic waves. The use of the preferred embodiment in this application, with the ability to locally measure, amplify and record digitally the signal, is the mainstay of this application. The use of optical power and transmission of the digital data in a binary form further eliminates the needs to generate an averaging of the various electrodes, as the local signal may indicate a "non-standard" behavior which is the underlying representation of a disease. The conventional prior art employs electrodes, which inherently must average the signal over a timespan, and thereby reduce the resolution on a local level.

<FIG> is additionally an example of the embodiment of the invention where we use a graphic representation of ganglionic plexus signal and where the analogue complex wave is preserved by the machinery described above as it demonstrates the use of the catheter sensing capabilities and enables a consistent and measurable application of contact force as a function of impedance value to distinguish between the contact force over the tissue measured and the anatomical structure, and by further providing a safe and optimal contact force between the catheter distal end and the biological site or structure. This measure of force is essential for the fidelity of the measurement of the site, as nerve activity is subject to the physical inverse law. Hence the operator needs to know that the biopotential of the site in question is a measure of a bioelectric potential of near field from the contacted tissue as opposed to far fields carried by the blood flow transfusing through the renal artery.

<FIG> are side cross sectional views of a patient's brain <NUM> and optical catheter <NUM> whereby an electroanatomic study of focal epilepsies and seizures that emanate from an epileptogenic focus within the brain. <FIG> is a diagram illustrating the use of the catheter <NUM> to identify a focal epileptic origin in the brain <NUM>. <FIG> is a diagram which in its upper portion illustrates the sensed biopotentials <NUM> of a partial epileptic seizure and use of the catheter <NUM> to identify a focal partial seizure epileptic origin <NUM> in the brain <NUM>. <FIG> indicates a clinical representation of a local seizure <NUM> identified by the corresponding electroencephalogram noted by the waveforms of the local seizure signals <NUM>, which indicates the seizure epicenter. <FIG> is a diagram which in its upper portion illustrates the sensed biopotentials <NUM> of a generalized epileptic seizure and use of the catheter <NUM> to identify a generalized focal epileptic origin <NUM> in both sides of the brain. <FIG> further elaborates on the ability of a precise biopotential catheter of the type described by this invention which enables the distinction of such an apparatus to discriminate between localized seizures verses global seizures <NUM>. The corresponding electroencephalogram <NUM> represents the various electrode of the existing arts of measuring brain output while the catheter <NUM> identifies the anatomical and topographical localization of the epicenter.

Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the embodiments. Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the embodiments as defined by the following embodiments and its various embodiments.

Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the embodiments as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the embodiments include other combinations of fewer, more or different elements, which are disclosed in above even when not initially claimed in such combinations. A teaching that two elements are combined in a claimed combination is further to be understood as also allowing for a claimed combination in which the two elements are not combined with each other but may be used alone or combined in other combinations. The excision of any disclosed element of the embodiments is explicitly contemplated as within the scope of the embodiments.

Claim 1:
An apparatus for use in combination with a computer for sensing biopotentials comprising: a catheter (<NUM>) comprising:
a plurality of sensing electrodes (<NUM>); a corresponding plurality of local amplifiers (<NUM>), each coupled to one of the plurality of sensing electrodes (<NUM>);
a data, control and power circuit (<NUM>) coupled to the plurality of local amplifiers(<NUM>);
and
a photonic device (<NUM>) configured for bidirectionally communicating an electrical signal with the data, control and power circuit(<NUM>) and for communicating an optical signal with an optical fiber (<NUM>);
where the photonic device is configured to bidirectionally communicate the optical signal with the optical fiber; and an optical interface device (<NUM>) to provide optical power to the optical fiber (<NUM>) and thence to the photonic device (<NUM>) and to receive optical signals through the optical fiber (<NUM>) from the photonic device(<NUM>), wherein the optical interface device is configured to bidirectionally communicate an electrical data, control and power signal to the computer,
further comprising a flexible printed circuit board (<NUM>) and where the local amplifiers and data, control and power circuit comprise application specific integrated circuits (ASICs) mounted on both sides of the flexible printed circuit board (<NUM>) within the catheter having a size of <NUM> French or smaller, or further comprising a flexible printed circuit board and where the local amplifiers and data, control and power circuit (<NUM>) comprise application specific integrated circuits, ASICs (<NUM>, <NUM>), mounted on both sides of the flexible printed circuit board (<NUM>) having a width of <NUM> or less and a height including the ASICs (<NUM>, <NUM>) of <NUM> or less.