Patent Description:
Reduced blood flow due to atherosclerotic occlusion of vessels is a major cause of vascular diseases. Pressure measurements in arterial vessels and particularly in coronary arteries prior to treatment have been used for lesion characterization and treatment selection. More specifically, pressure gradient across a lesion has been clinically used as an indicator for lesion severity. Measurements made during and after treatment allow one to assess therapy efficacy. Existing equipment for monitoring intravascular measurements have multiple, separate parts and bulky monitors. There is, accordingly, continuing interest in improved monitoring equipment.

<CIT> discloses a sensor assembly arranged to be disposed in a body for measuring a physiological variable. More particularly there is disclosed a sensor and guide wire assembly which communicates with an external unit by an inductive coupling between a first coil provided in the sensor assembly and a second, external coil which is disposed in or connected to the external unit.

<CIT> discloses a system and method that allows diagnosis of a patient for physiological abnormality such as a neurological deficiency.

<CIT> discloses a hand-held minimally dimensioned diagnostic device, having integrated distal end visualization.

The disclosed technology relates to diagnosing the severity of stenoses in the vasculature of a patient.

In one aspect of the disclosed technology, there is disclosed a portable apparatus according to claim <NUM>.

Features of some examples are set forth in the dependent claims.

The disclosed technology relates to diagnosing the severity of stenosis in the vasculature of a patient. The disclosed technology can be used as an adjunct to conventional angiographic procedures to provide important quantitative measurements of a blood vessel lumen.

Referring now to <FIG>, there is shown a block diagram of an exemplary intravascular diagnosis apparatus in accordance with the disclosed technology. The illustrated apparatus <NUM> includes a monitoring guidewire <NUM> and a portable display unit <NUM>. In one embodiment, the portable display unit <NUM> can be a handheld display unit, such that any and all aspects and embodiments described herein as being applicable to a portable display unit are also applicable to the disclosed handheld display unit. In one embodiment, the handheld display unit can be equal to or less than <NUM> x <NUM> x <NUM> in size. In operation, the monitoring guidewire <NUM> is introduced into the vasculature of a patient with the assistance of conventional interventional equipment known to those skilled in the art, such as catheters. The portable display unit <NUM> can communicate with the monitoring guidewire <NUM> and can display information based on the communications received from the monitoring guidewire <NUM>.

The illustrated monitoring guidewire <NUM> can include several components, including a core wire <NUM> and one or more sensors <NUM> disposed in a distal region of the core wire <NUM>. As used herein, the terms "distal" and "proximal" refer to physical directions within a blood vessel lumen. Specifically, in relation to the insertion point of a device into a patient, the term "distal" refers to the direction from the insertion point inwards into a blood vessel, and the term "proximal" refers to the direction from the inside of a blood vessel out towards the insertion point. As used herein, the terms "proximal" and "distal" can also refer to different ends of a device, with "proximal" being the end towards an insertion point into a blood vessel lumen and with "distal" being the end away from the insertion point.

With continuing reference to <FIG>, the one or more sensors <NUM> disposed in a distal region of the core wire <NUM> can include one or more hemodynamic pressure sensors and/or one or more temperature sensors. In one embodiment, the pressure sensor(s) can be a piezo-resistive pressure sensor. As illustrated in <FIG>, the monitoring guidewire <NUM> can also include a protective structure <NUM> surrounding the sensor(s) <NUM>, and can include a communication unit <NUM>. The protective structure <NUM> of the monitoring guidewire <NUM> will be described in more detail later herein in connection with <FIG>.

In one embodiment, the communication unit <NUM> can employ wireless communication technology such as bluetooth, WiFi (<NUM>), or any other wireless technology. In one embodiment, the communication unit <NUM> can be a wireline communication unit that can include one or more wires for communicating electromagnetic signals and/or one or more optical fibers for communicating optical signals. The monitoring guidewire <NUM> can include other components that are not illustrated, such as a power source, A/D converters, application specific integrated circuits (ASIC), a processor, memory, timing circuitry, and/or other power, analog, or digital circuitry. Such components will be known to those skilled in the art.

Referring now to the illustrated portable display unit <NUM>, the portable display unit <NUM> can include a display screen <NUM>, one or more batteries <NUM>, memory and/or storage <NUM>, a communication unit <NUM>, power management unit <NUM>, and a processor <NUM>. In one embodiment, the processor <NUM> can be a general purpose processor or can be an application specific integrated circuit. In one embodiment, the display screen <NUM> can be a liquid crystal display, an organic light emitting diode display, or another type of display technology. In one embodiment, the memory / storage <NUM> can include one or more of solid state memory / storage, magnetic disc storage, and/or any other type of memory / storage that will be known to those skilled in the art. In one embodiment, the memory / storage <NUM> can include software instructions that are executed by the processor <NUM>. In one embodiment, the communication unit <NUM> can employ wireless communication technology such as bluetooth, WiFi (<NUM>), or any other wireless technology. In one embodiment, the communication unit <NUM> can be a wireline communication unit that can include one or more wires for communicating electromagnetic signals and/or one or more optical fibers for communicating optical signals. The portable display unit <NUM> can include other components that are not illustrated, such as user interface, operating system software, display driver circuitry, A/D converters, application specific integrated circuits (ASIC), timing circuitry, and/or other power, analog, or digital circuitry. Such components will be known to those skilled in the art.

Referring now to <FIG>, there is shown a system block diagram of another embodiment of the disclosed technology. The monitoring guidewire contains a pressure sensor and/or other sensors at the distal end. The electrical signals from the sensor(s) can be sent over a wire connection to the portable display unit. The portable display unit can include a communications port that receives external sensor input such as aortic output pressure (AO IN) from pressure transducers / hemodynamic systems (not shown). The portable display unit can also include an output communication port for outputting data to an external storage device, to another display, to a printer, and/or to a hemodynamic system (not shown).

Referring now to <FIG>, there is shown an exemplary embodiment of the disclosed intravascular diagnosis apparatus. In one embodiment, the monitoring guidewire <NUM> can be approximately <NUM> centimeters in length. In other embodiments, the monitoring guidewire <NUM> can be another length. The monitoring guidewire <NUM> can have one or more sensors in the distal region <NUM> of the monitoring guidewire <NUM>. In the illustrated embodiment, the portable display unit <NUM> can have a small form factor such that it is a handheld display unit. In one embodiment, a handheld display unit can be equal to or less than <NUM> x <NUM> x <NUM> in size.

<FIG> is a diagram of another exemplary embodiment of the disclosed intravascular diagnosis apparatus. In the illustrated embodiment, the monitoring guidewire <NUM> can be attached and detached from a connector <NUM> of the portable display unit <NUM>. In one embodiment, the connector <NUM> can include a button (not shown) which opens an aperture in the connector <NUM>. To attach or detach the monitoring guidewire <NUM>, a user can press and hold the button of the connector <NUM> and insert the monitoring guidewire <NUM> into the aperture until the monitoring guidewire <NUM> is fully inserted into connector <NUM>. Once inserted, the user can release the button, which will then secure the monitoring guidewire <NUM> in place and provide a connection between the monitoring guidewire <NUM> and connector <NUM>. In other embodiments, the connector <NUM> can engage the monitoring guidewire <NUM> by a screw engagement, a twist engagement, a snap engagement, or an interference fit. The described types of engagement are exemplary and do not limit the scope of the disclosed technology. Other types of ways for the connector <NUM> to engage the monitoring guidewire <NUM> are contemplated to be within the scope of the disclosed technology.

In one embodiment, the connector connection establishes a communicative connection between the monitoring guidewire <NUM> and the portable display unit <NUM>. The monitoring guidewire <NUM> and the connector <NUM> can contain electrical wires that connect the monitoring guidewire <NUM> to the portable display unit <NUM> and convey signals from the monitoring guidewire sensor(s) to the portable display unit <NUM>.

In one embodiment, the connector connection establishes a mechanical connection between the monitoring guidewire <NUM> and the connector <NUM> to control the guidewire <NUM> within a vasculature. In the illustrated embodiment, the connector <NUM> is tethered to the main housing <NUM> of the portable display unit <NUM>. In one embodiment, the tether can be <NUM> inches to <NUM> inches long and can allow a user to manipulate the monitoring guidewire <NUM> freely without the portable display unit main housing <NUM> being an impediment. In one embodiment, the tether can be another length. In one embodiment (not shown), the connector can be a connection port integrated in the portable display unit main housing <NUM>.

In one embodiment, the connector <NUM> establishes a communicative connection with the monitoring guidewire <NUM>. In one embodiment, a torquer (not shown) can be configured to engage the monitoring guidewire <NUM> to control the guidewire within a vasculature when the monitoring guidewire <NUM> is not mechanically and/or electrically connected to the connector <NUM>. In one embodiment, the torquer can be configured to engage the monitoring guidewire <NUM> to control the guidewire within a vasculature when the monitoring guidewire <NUM> is mechanically and/or electrically connected to the connector <NUM>. In one embodiment, the monitoring guidewire <NUM> does not need a torquer or the connector <NUM> for insertion into the vasculature of a patient and for navigation therein, and provides this capability by itself.

With continuing reference to <FIG>, the portable display unit <NUM> includes a display screen <NUM> that can display sensor measurements and/or computed information (e.g., fractional flow reserve ratio), in numerical format and/or in waveform format. The portable display unit <NUM> can include one or more buttons (not shown) or a touch screen to allow a user to provide input to the portable display unit <NUM>. In one embodiment, the screen <NUM> of the portable display unit can be folded in the main housing <NUM> before use to minimize the size of packaging when delivering the portal display unit <NUM>. When a user takes the portable display unit <NUM> out of the packaging for use, the user can pivot the screen <NUM> from the folded position to an open position (as illustrated), providing an appropriate viewing angle to the user for the diagnosis procedure. In one embodiment, pivoting of the display screen <NUM> from the folded position to an open position acts as an ON switch that enables power to be delivered to the portable display unit.

In the illustrated embodiment, the portable display unit <NUM> also includes a communication port <NUM>. In one embodiment, the communication port <NUM> allows a user to connect the portable display unit <NUM> to an external system (not shown). The external system can communicate a sensor signal to the portable display unit <NUM> through the communication port <NUM>. In one embodiment, the sensor signal received at the communication port can be can be a pressure measurement and can be used in calculating fractional flow reserve.

Referring again to <FIG>, the monitoring guidewire <NUM> can include a protective structure <NUM> surrounding the sensor(s) <NUM>. With reference to <FIG>, there is shown a diagram of an exemplary protective structure <NUM> surrounding the sensor(s) <NUM> at the distal region of the monitoring guidewire. In the illustrated embodiment, the protective structure <NUM> is a housing that has been laser etched with a particular pattern cut to provide flexibility and/or torque translation at the distal tip or portion of the monitoring guidewire where the sensor <NUM> resides. The sensor(s) <NUM> can be situated in the laser etched housing at a window <NUM> in the housing so as to allow blood to contact the sensor(s) <NUM> in order to take sensor measurements. In the illustrated embodiment, the core wire <NUM> can be grinded to provide an appropriate profile for balancing flexibility and torque translation. In one embodiment, the monitoring guidewire need not include a core wire <NUM>. Rather, the protective structure <NUM> can extend along the entire monitoring guidewire or a substantial portion thereof, and can be laser etched along some or all portions to provide desired flexibility and/or torque translation.

Referring to <FIG>, there is shown a diagram of two exemplary protective structures surrounding the sensor(s) at the distal region of a monitoring guidewire. One of the embodiments is a laser etched housing as described in connection with <FIG>. The other embodiment provides a coil over the sensor(s) as the protective structure. The coil is relaxed to create a window where the sensor(s) are located to allow blood to contact the sensor(s). The illustrated embodiments are exemplary and do not limit the scope of protective structures contemplated in the disclosed technology. Other protective structures are contemplated to be within the scope of the disclosed technology.

Various aspects and embodiments of the disclosed technology have been described above. The illustrations and descriptions are merely exemplary and do not limit the scope of the disclosed technology. Even though not illustrated, various embodiments can be combined and are contemplated to fall within the scope of the disclosed technology. Furthermore, although certain features are illustrated as being in a particular location or device, the location and device are merely exemplary, and it is contemplated that various features can be located differently than as illustrated and still be within the scope of the disclosed technology.

The following description will now reference <FIG>, and in particular, the battery <NUM> and the power management unit <NUM> of the portable display unit <NUM>. In one aspect of the disclosed technology, the portable display unit <NUM> can be configured to operate for a predetermined duration or for a predetermined number of uses, and then be disposed. The battery <NUM> and/or power management unit <NUM> can implement these features so that the portable display unit <NUM> can be inoperable after being used for a particular duration or for a particular number of diagnosis procedures. Even so, the portable display unit <NUM> can be disposed while it is still operable, prior to it being inoperable.

In one embodiment, the predetermined duration can correspond to the approximate length of time of a single intravascular diagnosis procedure. In one embodiment, the predetermined duration can correspond to the approximate length of time of multiple diagnosis procedures, such as three procedures. In one embodiment, the predetermined duration can be twelve hours or twenty-four hours or several days. In one aspect of the disclosed technology, the portable display unit <NUM> can include one or more batteries <NUM> that are configured to power the portable display unit <NUM> for the desired duration, such that the batteries <NUM> are substantially depleted at the end of the desired duration. In one embodiment, the one or more batteries <NUM> are non-rechargeable, so that the portable display unit <NUM> is disposed after the batteries <NUM> are depleted. In one embodiment, the power management unit <NUM> can control the operating time of the portable display unit <NUM> by preventing the portably display unit <NUM> from powering down after the display screen <NUM> is turned on. In such an embodiment, the portable display unit <NUM> will operate continuously until the batteries <NUM> are depleted or substantially depleted. The portable display unit <NUM> can be disposed prior to the batteries <NUM> being depleted, while the portable display unit <NUM> is still operable.

In one embodiment, the portable display unit <NUM> can track the number of diagnosis procedures performed and can be configured to be inoperable after a particular number of procedures has been performed. In one embodiment, the portable display unit <NUM> can track the number of diagnosis procedures performed by the number of times the portable display unit <NUM> has been turned on and/or off. In one embodiment, the portable display unit <NUM> can be configured to be inoperable after a single diagnosis procedure has been performed. In one aspect of the disclosed technology, the power management unit <NUM> can prevent the portable display unit <NUM> from being powered on after the particular number of procedures has been reached. The batteries <NUM> can be rechargeable and can be recharged by a power source of the portable display unit <NUM> and/or by a power source external to the portable display unit <NUM>. Even when the batteries <NUM> are not yet depleted, the power management unit <NUM> can cause the portable display unit <NUM> to be inoperable by preventing the batteries <NUM> from powering the portable display unit <NUM>.

The intravascular diagnosis procedure will now be described with continuing reference to <FIG> and with reference to <FIG>. Diagnosing the severity of one or more stenoses within the vasculature of a patient has been studied based on hemodynamic pressure measurements distal to a stenosis in comparison with aortic output pressure. The ratio of pressure distal to a stenosis to the aortic output pressure is known as "factional flow reserve", or FFR. The value of the FFR indicates the severity of the stenosis, and clinical data provides guidance on the type of surgical procedure that would be effective for particular FFR ranges.

The disclosed technology includes multiple ways of computing FFR, including what will be referred to herein as "push-forward FFR", "pull-back FFR", and "simultaneous FFR". Each of these can be implemented by software code or machine code stored in memory / storage <NUM> of the portable display unit <NUM> (<FIG>). The processor <NUM> can execute the software code to compute the FFR, and the resulting information can be displayed on the display screen <NUM>. Each of the computation methods will now be described.

Simultaneous FFR involves simultaneous pressure readings from two separate pressure sensors, and a computation of FFR in real-time as the pressure readings from the two separate pressure sensors are received. Referring to <FIG> and <FIG>, one pressure sensor is located in the monitoring guidewire <NUM>, and is used to measure pressure distal to a stenosis in a patient. The pressure readings can be communicated by the communication unit <NUM> of the monitoring guidewire <NUM> to the communication unit <NUM> of the portable display unit <NUM>.

This communication can be a wireless communication or can be a wireline communication through, for example, the connector illustrated in <FIG>. The other pressure sensor can measure aortic output pressure and is external to the apparatus <NUM> of <FIG>. The portable display unit <NUM> can designate the received pressure measurements as pressure distal to a stenosis (<NUM>). The external sensor readings can be communicated to the communication unit <NUM> of the portable display unit by, for example, the communication port illustrated in <FIG> (<NUM>). The portable display unit <NUM> can designate the received pressure measurements as pressure proximal to a stenosis (<NUM>). The portable display unit <NUM> can compute the simultaneous FFR as the pressure measurements are received (<NUM>), by the formula: FFR = (Psensor-Pra)/(Pport-Pra ), where:.

In one embodiment, the moving means over time can compute the mean over a window of time that spans one heartbeat. In other embodiments, the window of time can span less than one heartbeat or more than one heartbeat. As new sensor measurements are received over time (<NUM>, <NUM>), the window can include newer measurements and remove older measurements to compute the moving means.

The portable display unit <NUM> can receive pressure measurements and can compute the simultaneous FFR based on the received measurements. The portable display unit <NUM> can store the received pressure measurements and/or the computed simultaneous FFR in memory / storage <NUM>, and can display the computed simultaneous FFR and/or a graph of the received pressure measurements on the display screen <NUM> (<NUM>).

In contrast to simultaneous FFR, the push-forward FFR does not receive external pressure measurements. With continuing reference to <FIG>, push-forward FFR is computed using pressure measurements from only the pressure sensor(s) <NUM> in the distal region of the monitoring guidewire <NUM>. Using traditional angiography, a stenosis can be located and, as shown in <FIG>, the monitoring guidewire can be inserted into a patient to a point proximal to the stenosis. Pressure can be measured at this position by the sensor(s) <NUM> and communicated by the communication unit <NUM> to the portable display unit <NUM> (<NUM>). The portable display unit <NUM> can store the measurements in this position in the memory / storage <NUM> as pressure proximal to a stenosis (<NUM>). Next, the monitoring guidewire <NUM> can be pushed forward past the stenosis to a point distal to the stenosis, as illustrated in <FIG>. Pressure can be measured at this position by the sensor(s) <NUM> and communicated by the communication unit <NUM> to the portable display unit <NUM> (<NUM>). The portal display unit <NUM> can designate the pressure measurements received at this position as pressure distal to the stenosis (<NUM>). The processor <NUM> can compute the push-forward FFR (<NUM>) by the formula: FFR = (Psensor-Pra)/(Psaved-Pra ), where:.

Aspects of computing the moving means over time were described above in connection with simultaneous FFR, and such aspects apply to push-forward FFR as well.

The portal display unit <NUM> can display the computed push-forward FFR and/or a graph of the received and stored pressure measurements (<NUM>).

Push-forward FFR can be computed in the case of one stenosis and can also be computed in the case of multiple stenosis. In either case, Psaved are moving means over time of pressure measurements proximal to all of the stenosis. In one embodiment, Psaved are moving means over time computed based on recorded pressure measurements. In one embodiment, Psaved are moving means over time computed and recorded as pressure measurements are received, and the pressure measurements may or may not be recorded. For example, in the case of two stenoses, Psaved are based on pressure measurements proximal to both the first and second stenosis. When the monitoring guidewire pressure sensor <NUM> is pushed forward to a position between the first and the second stenosis, Psensor are based on real time pressure measurements between the two stenoses. Push-forward FFR can be calculated in this position and displayed on the display screen <NUM>. When the monitoring guidewire pressure sensor <NUM> is pushed forward to a position distal to both the first and second stenoses, Psensor are based on real time pressure measurements distal to both of the two stenoses. Push-forward FFR can be calculated in this position and displayed on the display screen <NUM>. Thus, push-forward FFR enables FFR to be computed and displayed as the monitoring guidewire <NUM> is pushed forward across one or more stenoses in a blood vessel lumen. The only measurements and/or moving means that need to be recorded for push-forward FFR computations are pressure measurements and/or moving means of pressure measurements proximal to all stenoses, and this is performed at the outset.

Similar to push-forward FFR, the pull-back FFR does not receive external pressure measurements. Rather, pull-back FFR is computed using pressure measurements from only the pressure sensor(s) <NUM> in the distal region of the monitoring guidewire <NUM>. Using traditional angiography, a stenosis can be located and, as shown in <FIG>, the monitoring guidewire can be inserted into a patient to a point distal to the stenosis. Pressure can be measured at this position by the sensor(s) <NUM> and communicated by the communication unit <NUM> to the portable display unit <NUM> (<NUM>). The portable display unit <NUM> can store the measurements in this position in the memory / storage <NUM> as pressure distal to a stenosis (<NUM>). Next, the monitoring guidewire <NUM> can be pulled back through the stenosis to a point proximal to the stenosis, as illustrated in <FIG>. Pressure can be measured at this position by the sensor(s) <NUM> and communicated by the communication unit <NUM> to the portable display unit <NUM> (<NUM>). The portable display unit <NUM> can designate the measurements received in this position as pressure proximal to a stenosis (<NUM>). The processor <NUM> can compute the pull-back FFR (<NUM>) by the formula: <MAT> where:.

Aspects of computing the moving means over time were described above in connection with simultaneous FFR, and such aspects apply to pull-back FFR as well.

The portal display unit <NUM> can display the computed pull-back FFR and/or a graph of the received and stored pressure measurements (<NUM>).

Pull-back FFR can be computed in the case of one stenosis and can also be computed in the case of multiple stenosis. In either case, Psensor are based on real-time pressure measurements proximal to all of the stenosis, which are the final pressure measurements that are taken. For example, in the case of two stenoses, the monitoring guidewire pressure sensor <NUM> is initially placed at a position distal to both the first and the second stenoses. Pressure can be measured at this position by the sensor(s) <NUM> and communicated by the communication unit <NUM> to the portable display unit <NUM>. In one embodiment, Psaved_d1 are moving means over time computed later based on recorded pressure measurements. In one embodiment, Psaved_d1 are moving means over time computed and recorded while the pressure measurements are received in this position, and the pressure measurements may or may not be recorded. The memory / storage <NUM> can record the pressure measurements in this position and/or computed moving means over time based on such pressure measurements. Pull-back FFR cannot yet be calculated because there is no real-time measurement yet proximal to all of the stenoses. Next, the monitoring guidewire <NUM> can be pulled back through the first stenosis to a point between the first and second stenosis. Pressure can be measured at this position by the sensor(s) <NUM> and communicated by the communication unit <NUM> to the portable display unit <NUM>. In one embodiment, Psaved_d2 are moving means over time computed later based on recorded pressure measurements. In one embodiment, Psaved_d1 are moving means over time computed and recorded while the pressure measurements are received in this position, and the pressure measurements may or may not be recorded. The memory / storage <NUM> can record the pressure measurements in this position and/or computed moving means over time based on such pressure measurements. Once again, pull-back FFR cannot yet be calculated because there is no real-time measurement yet proximal to all of the stenoses. Lastly, the monitoring guidewire <NUM> can be pulled back through the second stenosis to a point proximal to both the first and second stenosis. Real-time pressure can be measured at this position by the sensor(s) <NUM> and communicated by the communication unit <NUM> to the portable display unit <NUM>. Only at this point are there enough measurements to compute the two pull-back FFR: FFR<NUM> = (Psaved_d1-Pra)/(Psensor-Pra ) and FFR<NUM> = (Psaved_d2-Pra)/(Psensor-Pra ). Therefore, pull-back FFR does not allow FFR to be calculated and displayed as the monitoring guidewire is being pulled back through multiple stenoses.

Accordingly, three computations for fractional flow reserve have been described above in connection with <FIG>. In one aspect of the disclosed technology, and with reference to <FIG>, the portable display unit <NUM> is configured with capability to compute fractional flow reserve using any of the three ways. In one embodiment, the portable display unit <NUM> can be configured to automatically use one of the three ways of computing fractional flow reserve. In one embodiment, the portable display unit <NUM> can be configured to automatically select one of the three ways of computing fractional flow reserve when a condition is present and to automatically select another of the three ways of computing fractional flow reserve when other conditions are present. In one embodiment, the portable display unit <NUM> can be configured to permit a user to manually select one of the three ways of computing fraction flow reserve.

The disclosed technology measures pressure and calculates fractional flow reserve (FFR). FFR is a calculation that has been clinically demonstrated to assist in determining whether to treat or not to treat an intermediate coronary lesion. Using the disclosed technology will thus assist a physician in determining what to do with an intermediate lesion. The disclosed FFR equations are exemplary and do not limit the scope of the disclosed technology. Other ways to compute FFR are contemplated to be within the scope of the disclosed technology.

Claim 1:
A portable apparatus (<NUM>) for intravascular diagnosis, the portable apparatus comprising:
a monitoring guidewire (<NUM>) comprising a core wire (<NUM>) and a pressure sensor (<NUM>) disposed in a distal region of the core wire; and
a display unit (<NUM>) configured to be inoperable after a predetermined number of uses or after a predetermined duration of use, the display unit (<NUM>) comprising a processor and a display screen (<NUM>), wherein the display unit (<NUM>) is capable of receiving communication from the monitoring guidewire (<NUM>), is configured to perform computations using the processor based on communications received from the monitoring guidewire (<NUM>), and is configured to display information on the display screen (<NUM>) based on the computations, wherein the computations include calculating fractional flow reserve.