Abstract:
A sensor wire system is provided. The system includes a sensor wire body configured to be inserted into a blood vessel of a patient, the sensor wire body having a distal portion; a sensor coupled to the distal portion of the sensor wire body and configured to obtain intravascular information associated with the blood vessel; and an electronics unit coupled to the sensor wire body and configured to wirelessly transmit the intravascular information to a receiver unit outside of the patient, wherein the electronics unit is further configured to vary a frequency at which the intravascular information is wirelessly transmitted. Associated devices and methods are also provided.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/364,972, filed Feb. 12, 2012, now U.S. Pat. No. ______, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Heart disease is a leading cause of death for men and women in the United States. Consequently, there are numerous medications, medical procedures, and medical devices aimed at diagnosing and treating heart disease. 
         [0003]    One type of medical procedure aimed at diagnosing heart disease is angiography. The procedure requires injecting a contrast agent into the blood stream and then taking x-rays to determine if there is a blockage within the blood vessel. A problem with an angiography is that the procedure can only determine if a blockage exists, but not whether the blockage is actually affecting the blood flow within the blood vessel. As a result, many patients elect to have unnecessary procedures to treat the blockage without confirming the severity of the blockage. 
         [0004]    Another procedure for assessing heart disease is fractional flow reserve (FFR). FFR is a technique used in coronary catheterization to measure the pressure difference and thus blood flow across a partially blocked or constricted artery. Using a guidewire system, measurements are taken on both sides of a blockage within a blood vessel to determine if there is a pressure gradient or reduced blood flow due to the blockage. If there is no drop in pressure (or a nominal drop), then there may be no need for further medical intervention because the blockage is not significantly impeding the flow of blood. Conversely, if there is a significant drop across the blockage, then the blockage may need to be removed or treated because the blood flow is impaired by the blockage. 
         [0005]    Generally, the FFR procedure is performed by inserting a guidewire system into the femoral or radial artery of the patient. The guidewire is maneuvered into position within a partially blocked blood vessel, and a sensor at the distal end of the guidewire is used to measure pressure, temperature, and/or blood flow to determine the severity of the blockage. The sensor is connected to a display device such as a monitor of a computer screen to display the patient&#39;s readings during the procedure. 
       SUMMARY OF THE INVENTION 
       [0006]    A problem with some sensor devices is that they must be physically connected to both a power source and display device during the procedure. These requirements limit the range and mobility during the procedure and create wire management challenges. They require the operator to manipulate the sensor devices so that they are properly located in the patient. The electrical connectors must be uncovered or cleaned for connection to display and data processing devices. This adds extra steps and may involve breaches of the procedure&#39;s sterile field. 
         [0007]    The present invention is directed to a preferably single-use sensor wire system and method that can have both an integrated power source and integrated antenna for wireless transmission. 
         [0008]    In general according to one aspect, the invention features a sensor wire system. It comprises a sensor wire body having a distal end that is inserted into a blood vessel of a patient, a sensor that is mounted at the distal end of the sensor wire body, an electronics unit of the distal end of the sensor wire body that wireles sly transmits information generated by the sensor to a receiver unit outside of the patient, and a power source that supplies power to the electronics unit. 
         [0009]    In preferred embodiments, the sensor is a pressure sensor, a temperature sensor, and/or a blood flow sensor. In other examples, it is an imaging device, such as an IVUS, FLIVUS, OCT, spectroscopic, ICE, or forward looking ICE analysis device, with encoded images from the imaging device being broadcast to the receiver unit. 
         [0010]    In one embodiment, the power source is a power harvesting device, such as one that converts the cyclic pressure changes of surrounding blood into power to the electronics unit. In other cases, the power source is a battery, such as a battery that is activated upon insertion into the patient and that powers the electronics unit until the power source is depleted. 
         [0011]    In general according to another aspect, the invention features a method of using a sensor wire. This comprises inserting a sensor wire body having a distal end into a blood vessel of a patient, mounting a sensor to the distal end of the sensor wire body, supplying power to an electronics unit, and transmitting information generated by the sensor to a receiver unit via the electronics unit. 
         [0012]    In an exemplary aspect, the present disclosure is directed to a sensor wire system. The sensor wire system includes a sensor wire body configured to be inserted into a blood vessel of a patient, the sensor wire body having a distal portion; a sensor coupled to the distal portion of the sensor wire body and configured to obtain intravascular information associated with the blood vessel; and an electronics unit coupled to the sensor wire body and configured to wireles sly transmit the intravascular information to a receiver unit outside of the patient, wherein the electronics unit is further configured to vary a frequency at which the intravascular information is wirelessly transmitted. 
         [0013]    In some embodiments, the sensor wire body comprises a radio frequency antenna. In some embodiments, the sensor wire body is configured to wirelessly transmit the intravascular information. In some embodiments, the electronics unit includes at least one of a sensor control circuit, a radio frequency circuit, or a signal amplifier circuit. In some embodiments, the electronics unit includes: a sensor control circuit configured to perform at least one of processing a signal associated with the intravascular information or encoding the signal for wireless transmission; a radio frequency circuit configured to perform at least one of wirelessly transmitting the signal at a particular frequency or varying the frequency at which the signal is wireles sly transmitted; and a signal amplifier circuit configured to amplify the signal prior to being wirelessly transmitted. In some embodiments, the electronics unit is configured to vary the frequency at which the intravascular information is wirelessly transmitted based on a frequency of another device. In some embodiments, the system further comprises the receiver unit. In some embodiments, the system further comprises a computer system in communication with the receiver unit. In some embodiments, the computer system is in communication with at least one of: a display device configured to display a visual representation of the intravascular information; a storage medium configured to store the intravascular information; or a printer configured to generate a printout of the intravascular information. In some embodiments, the sensor comprises at least one of a pressure sensor, a temperature sensor, a flow sensor, or an imaging device. 
         [0014]    In an exemplary aspect, the present disclosure is directed to a method of sensing intravascular information. The method includes obtaining intravascular information associated a blood vessel of a patient using a sensor wire system, the sensor wire system including: a sensor wire body positioned within the blood vessel and having a distal portion; a sensor coupled to the distal portion of the senor wire body; and an electronics unit coupled to the sensor wire body and configured to wirelessly transmit the intravascular information; and wirelessly transmitting the intravascular information, using the electronics unit, to a receiver unit outside of the patient; and varying, using the electronics unit, a frequency at which the intravascular information is wireles sly transmitted. 
         [0015]    In some embodiments, the sensor wire body comprises a radio frequency antenna. In some embodiments, wireles sly transmitting the intravascular information includes wireles sly transmitting the intravascular information using the sensor wire body. In some embodiments, the electronics unit includes at least one of a sensor control circuit, a radio frequency circuit, or a signal amplifier circuit. In some embodiments, the method further includes at least one of: processing a signal associated with the intravascular information data using the sensor control circuit; encoding the signal for wireless transmission, using the sensor control circuit; wirelessly transmitting the signal at a particular frequency, using the radio frequency circuit; varying the frequency at which the signal is wireles sly transmitted, using the radio frequency circuit; or amplifying the signal prior to being wireles sly transmitted, using the signal amplifier circuit. In some embodiments, the method further includes receiving the intravascular information at the receiver unit. In some embodiments, the method further includes receiving the intravascular information at a computer system in communication with the receiver unit. In some embodiments, the method further includes at least one of: displaying a visual representation of the intravascular information using a display device in communication with the computer system; storing the intravascular information on a storage medium in communication with the computer system; or generating a printout of the intravascular information using a printer in communication with the computer system. In some embodiments, the sensor comprises at least one of a pressure sensor, a temperature sensor, a flow sensor, or an imaging device. In some embodiments, the varying a frequency at which the intravascular information is wirelessly transmitted is based on a frequency of another device such that the sensor wire system and the another device operate without interference. 
         [0016]    The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the invention. Of the drawings: 
           [0018]      FIG. 1  is a schematic illustration showing a sensor wire inserted into a patient&#39;s body. 
           [0019]      FIG. 2  schematic cross-sectional view showing a sensor wire within a partially blocked blood vessel of a patient that is wirelessly transmitting information to a receiver. 
           [0020]      FIG. 3  is schematic cross-sectional view showing the distal end of a sensor wire with a protective sheath. 
           [0021]      FIG. 4  is a block diagram of the electronics unit in the distal end of the sensor wire. 
           [0022]      FIG. 5  is a block diagram of the electronics unit in the distal end of the sensor wire according to another embodiment using a reserve battery power source. 
           [0023]      FIG. 6  is a block diagram of the electronics unit in the distal end of the sensor wire with a battery power source at the proximal end. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]      FIG. 1  is an illustration of a sensor wire  104  that is inserted into a patient&#39;s body  102 . 
         [0025]    In operation, the sensor wire system  104  is inserted into the artery, such as the femoral artery, of a patient  102  and guided through the blood vessels until arriving at a potentially partially blocked blood vessel of interest within the patient&#39;s body  102 , such as a coronary artery. In alternative embodiments, the sensor wire  104  is inserted via the radial or other artery, or vein. In other applications, other arteries or veins are the vessels of interest. 
         [0026]      FIG. 2  illustrates the sensor wire system  104  within a partially blocked blood vessel of a patient  102  that is wirelessly transmitting information to a receiver  218 . In one embodiment, the sensor wire  104  measures pressure, blood flow, and/or temperature within the blood vessel  202  of the patient  102 . Typically, the distal end  215  of the sensor wire system  104  is inserted through the femoral artery and guided to the blocked blood vessel  202  by holding the sensor wire body. Steering the sensor wire  104  within the blood vessels is often performed by manually manipulating the proximal end  214  of the sensor wire body  105  or using a separate guide wire. 
         [0027]    Once in position, the sensor  212  measures pressure, blood flow and/or temperature and encodes the information in the form of electrical signals. In a preferred embodiment the sensor  212  includes a pressure transducer, a flow detector, and a temperature transducer. 
         [0028]    In other embodiments, the sensor  212  further includes an imaging system. In one example, the sensor  212  included an intravascular ultrasound (IVUS) device. In another variant, the sensor  212  includes a forward-looking IVUS (FLIVUS) device. In still other embodiments, the sensor  212  includes optical coherence tomography (OCT), near infrared spectroscopic, intracardiac echocardiography (ICE), and forward looking ICE devices. 
         [0029]    The electrical signals generated by the sensor  212  are relayed to the electronics unit  210 , which processes the signals. The information is then wirelessly transmitted to an external receiver  218 . The sensor wire body  105  is preferably fabricated from conductive materials such that the sensor wire body  105  operates as a radio frequency antenna capable of broadcasting the information to the external receiver  218 . 
         [0030]    Depending on the implementation, the sensor signals broadcast from the antenna are the encoded time-varying pressure, flow, and temperature detected by the sensor  212 . 
         [0031]    In the cases where the sensor  212  includes an imaging modality, the broadcast sensor signals are encoded images from the IVUS, FLIVUS, OCT, spectroscopic, ICE, or forward looking ICE analysis. 
         [0032]    Additionally, a power source  208  of the sensor wire system  104  supplies power to the electronics unit  210  and possibly the sensor  212  depending on the sensor technology used. In a typical implementation, the power source is a battery. However, in other embodiments, one or more storage capacitors supply the power requirements. 
         [0033]    In a one embodiment, the battery power source  208  includes an anode and a cathode, but initially lacks the necessary electrolyte needed to complete a battery. In operation, the power source  208  is activated by injecting an electrolyte  216  into the sensor wire  104  or between the sensor wire  104  and a surrounding protective sheath. The electrolyte reacts with the anode and cathode to create a battery. Once the power source  210  is activated, the sensor wire system  104  wireles sly transmits the information generated by the sensor  212  until the power source  208  is exhausted. 
         [0034]    In still another embodiment, the power for the electronics unit  210  is provided by a power harvesting system that converts the biological motion of the patient into power. In one example, the power source  208 , or possibly the sensor wire body  105  itself, includes a piezo-electric power source that converts the cyclic pressures changes of the surrounding blood into electricity that powers the electronics unit  210 . 
         [0035]    The receiver  218  is connected to a display device  220  that displays the information on a screen. The display device is part of a computer system or medical workstation that includes a storage medium and printer to generate a printout of the information as well as to store a copy for future analysis. 
         [0036]      FIG. 3  is an illustration of the distal end of a sensor wire  104  with a protective sheath  206 . 
         [0037]    In a preferred embodiment, the sensor wire  104  is contained within a protective sheath  206 . The sheath  206  isolates the sensor  212 , electronics unit  210  and power source  208 , and wire body  105  from the patient&#39;s body  102 . In alternative embodiments, however, the sensor wire  104  will not have a protective sheath. 
         [0038]      FIG. 4  is a block diagram of the electronics unit  210  in the distal end  215  of the sensor wire system  104 . 
         [0039]    In a preferred embodiment, the sensor  212  is located in the tip of the distal end of the sensor wire  104 . The sensor  212  generates pressure, blood flow and/or temperature information, usually in the form of electrical signals generated by a transducer. The electrical signals from the sensor  212  are sent to the electronics unit  210 . The electrical signals are processed by the sensor control circuit  224  and encoded for transmission to the external receiver  218  and displayed on the screen  220 . 
         [0040]    The radio frequency (RF) circuit  226  is designed to wireles sly broadcast the information via the sensor wire body  105  at a specific frequency. In an alternative embodiment, the RF circuit allows the frequency to be varied so that multiple sensor wires operate at different frequencies in close spectral proximately without creating interference. 
         [0041]    The electronics control unit  210  further includes a signal amplifier circuit  222  to amplify the signal prior to being wirelessly broadcast to the receiver  218 . 
         [0042]    An added benefit is that the sensor wire  104  can be used as a guidewire. Catheters can be threaded over the sensor wire  104 . This process is facilitated by the fact that there are no electrical connections to the external receiver. 
         [0043]      FIG. 5  is a block diagram of the electronics unit  210  in the distal end  215  of the sensor wire system  104  according to another embodiment. 
         [0044]    In this example, the power source  208  is a reserve battery. These are devices that are commonly used in ordinance, for example. Reserve batteries are activated by addition of material or a change in temperature, the activator  250 . With this addition or change, then the reserve battery  208  delivers current for several minutes to hours. 
         [0045]    In one example, the activator  250  is water or other fluid that functions as an electrolyte causing the battery  208  to begin delivering current and thus power the electronics unit  210 . The medical professional, in one example, injects the activator material  250  into the battery or breaks a bladder or capsule filled with the material, which then flows into the battery. In another example the activator is a gas that is either the active cathode material or part of the electrolyte. 
         [0046]      FIG. 6  is a block diagram of the electronics unit  210  in the distal end  215  of the sensor wire system  104  according to another embodiment, in which the reserve battery  208  is located at the proximal end  215  of the sensor wire system  104 . This embodiment has the advantage that the reserve battery  208  can be activated by the operator/surgeon only after the wire system  104  has been placed in the patient. Wires  209  extending through the system  104  carry the current from the reserve battery  208  at the proximal end  214  to the electronics unit  210  at the distal end  215 . 
         [0047]    In another example, the reserve battery  208  is wire shaped extending through the length of the sensor wire system  104 . In some examples, the wire-shaped reserve battery provides mechanical support for the system  104 . 
         [0048]    While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.