Abstract: A catheter is disclosed for providing a pressure measurement at a vascular lesion. The catheter includes a tubular component having dual lumens along at least a segment thereof in which a first lumen acts as a pressure inlet and a second lumen allows the catheter to be tracked over a guidewire. A plurality of openings are located along a distal segment of the tubular component that permit blood flow into the first lumen when disposed in vivo. A pressure sensor is located within a handle component of the catheter or within the tubular component to be in fluid communication with a proximal end of the first lumen. When the catheter is positioned at the vascular lesion, the first lumen fills with blood via the plurality of openings such that the pressure sensor is able to sense a pressure of the blood at a distal end of the catheter.

Abstract: Systems and methods using a database of physiological information for the design, development, testing and use of therapeutics. In one aspect, the physiological information can include at least one of: hemodynamic monitoring information, pulmonary arterial pressure, cardiac output, heart rate, respiratory rate, peripheral vascular resistance, total peripheral resistance or dicrotic notch information. Optionally, the cardiovascular physiology information can include ambulatory physiological information.

Abstract: Embodiments hereof relate to methods and systems for determining a pressure gradient across a lesion of a vessel without requiring the use of a pharmacological hyperemic agent. A measurement system includes at least an injection catheter and a pressure-sensing instrument or guidewire slidingly disposed through the catheter, the pressure-sensing guidewire including at least one pressure sensor configured to obtain a pressure measurement for use in determining the pressure gradient across the lesion. The catheter is configured to deliver or inject a non-pharmacological fluid, such as saline or blood, across the lesion in order to increase a flow rate there-through, thereby simulating hyperemia without the use of a pharmacological hyperemic agent. Once an increased flow rate that simulates hyperemia is achieved, the pressure sensor of the pressure-sensing guidewire may be utilized to measure the pressure gradient across the lesion in order to assess the severity of the lesion.

Abstract: An apparatus for determining cardiac performance in the patient. The apparatus includes a conductance catheter for measuring conductance and blood volume in a heart chamber of the patient. The apparatus includes a processor for determining instantaneous volume of the ventricle by applying a non-linear relationship between the measured conductance and the volume of blood in the heart chamber to identify mechanical strength of the chamber. The processor is in communication with the conductance catheter. Methods for determining cardiac performance in a patient. Apparatuses for determining cardiac performance in a patient.

Abstract: Embodiments of the present disclosure are configured to assess the severity of a blockage in a vessel and, in particular, a stenosis in a blood vessel. In some particular embodiments, the devices, systems, and methods of the present disclosure are configured to assess the severity of a stenosis in the coronary arteries without the administration of a hyperemic agent. In some embodiments, the devices, systems, and methods of the present disclosure are configured to optimize proximal and distal pressure measurements utilized to assess the vessel.

Abstract: A medical system utilizes a guide wire with a fluid filled internal lumen and a pressure measurement system to measure blood pressure in a body vessel. The guide wire includes an internal lumen with a distal opening for admitting fluid flow. The internal lumen is filled with a fluid or other media which can transmit pressure along the guide wire. The pressure measurement system includes a pressure transducer in fluid communication with the internal lumen of the guide wire. Pressure waveform in the body vessel are transmitted through the fluid or media from the distal opening of the internal lumen to the pressure transducer. The pressure transducer is in communication with a processor (with display) for determining the pressure acting on the pressure transducer. A pump with a fluid reservoir in fluid communication with the internal lumen of the guide wire is controlled by the processor. The pump introduces additional fluid into the guide wire lumen.

Abstract: A transducer interface system/method allowing conversion from an analog sensor input to a standardized analog output interface is disclosed. In some preferred embodiments the system/method permits a fiber optic pressure sensor to be interfaced to a standard patient care monitor (PCM) system using standardized Wheatstone Bridge analog interface inputs. Within this context the Wheatstone Bridge sensed output is defined by stimulus from the PCM and modulation of bridge element values by the conditioned output of an analog pressure sensor. The use of analog-to-digital-to-analog conversion in this transducer interface permits retrofitting of PCM devices having analog Wheatstone Bridge inputs with advanced patient monitoring sensors without the need for specialized modifications to the baseline PCM data collection framework. Methods disclosed herein include techniques to connect arbitrary types/numbers of analog sensors to traditional PCM systems without the need for PCM system hardware/software modifications.

Abstract: A transducer interface system/method allowing conversion from an analog sensor input to a standardized analog output interface is disclosed. In some preferred embodiments the system/method permits a fiber optic pressure sensor to be interfaced to a standard patient care monitor (PCM) system using standardized Wheatstone Bridge analog interface inputs. Within this context the Wheatstone Bridge sensed output is defined by stimulus from the PCM and modulation of bridge element values by the conditioned output of an analog pressure sensor. The use of analog-to-digital-to-analog conversion in this transducer interface permits retrofitting of PCM devices having analog Wheatstone Bridge inputs with advanced patient monitoring sensors without the need for specialized modifications to the baseline PCM data collection framework. Methods disclosed herein include techniques to connect arbitrary types/numbers of analog sensors to traditional PCM systems without the need for PCM system hardware/software modifications.

Abstract: An intravascular sensor delivery device for measuring a physiological parameter of a patient, such as blood pressure, within a vascular structure or passage. In some embodiments, the device can be used to measure the pressure gradient across a stenotic lesion or heart valve, such as a fractional flow reserve (FFR) across a stenotic lesion. The sensor delivery device has a distal sleeve configured to pass or slide over a standard medical guidewire. The sensor delivery device can be sized to pass over different sizes of guidewires to enable usage in coronary and peripheral arteries, for example. The sensing mechanism (sensor) can be a fiber optic pressure sensor, such as a MEMS-based FabryPerot fiber optic pressure sensor, for example, or could employ some other technology, e.g., MEMS capacitive or piezoresistive sensor.

Abstract: Medical devices and methods for making and using medical devices are disclosed. An example method may include a method for calculating fractional flow reserve including providing a pressure sensing guidewire, advancing the pressure sensing guidewire through a blood vessel to a first position distal of an intravascular occlusion, determining a distal pressure within the body lumen with the pressure sensing guidewire, proximally shifting the pressure sensing guidewire to a second position proximal of the occlusion, determining a proximal pressure within the body lumen with the pressure sensing guidewire, measuring an aortic pressure, and calculating a pressure drift. The pressure drift may be the difference between the aortic pressure and the proximal pressure. The method may also include calculating a drift-compensated fractional flow reserve. The drift-compensated fraction flow reserve may correspond to (the distal pressure+the pressure drift) divided by the aortic pressure.

Abstract: Intravascular devices and systems include a flexible elongate member having a component configured to detect a physiological condition of a patient when the flexible elongate member is in a vasculature of the patient. The probe may also include a connector junction non-rotatably and permanently secured to the proximal portion of the flexible elongate member. The connector junction may be sized for grasping by a health care provider and for rotation to rotate the flexible elongate member when the flexible elongate member is in a vasculature of the patient. The connector junction may include a slack chamber to accommodate slack in a conductor that may be utilized when the flexible elongate member is introduced through tortious vasculature.

Abstract: A catheter for delivering securing elements to a tissue, such as a blood vessel, and imaging the tissue before, after, or during the imaging. The catheters incorporate intravascular ultrasound (IVUS) imaging, including Focused Acoustic Computed Tomography (FACT), as well as optical coherence tomography (OCT).

Abstract: In a method for the intermittent occlusion of a vein draining the organ system, in which the vein is occluded by an occlusion device, the fluid pressure in the occluded vein is continuously measured and stored, the behavior of the fluid pressure is determined as a function of time, and the occlusion of the vein is triggered and/or released as a function of at least one characteristic value derived from the pressure measurements, pressure is applied during the occlusion in a pulsating manner. The device for the intermittent occlusion of a vein, including an occlusion device, a pressure measuring device for continuously measuring the fluid pressure in the occluded vein, and a memory for storing the fluid pressure behavior as a function of time, means are provided for applying a pulsating pressure in the occluded vein.

Abstract: Devices, systems, and methods for visually depicting a vessel and evaluating treatment options are disclosed.

Abstract: A transmitter unit with an attachable energy source is provided for a sensor guidewire. The transmitter unit is adapted to be connected to a proximal end of a sensor guidewire provided, at its distal end, with a sensor to measure a physiological parameter inside a patient. In some embodiments, the transmitter unit is adapted to wirelessly communicate by a communication signal with a communication unit, arranged in connection with an external device, in order to transfer measured physiological data to the external device. The attachable energy source can be a battery pack or battery holder provided with connecting electrical connecting surfaces. Preferably, the connection is protected from penetrating fluids by a protective seal.

Abstract: A method and apparatus for determining a cardiovascular parameter including receiving an input signal corresponding to an arterial blood pressure measurement over an interval that covers at least one cardiac cycle, determining a propagation time of the input signal, determining at least one statistical moment of the input signal, and determining an estimate of the cardiovascular parameter using the propagation time and the at least one statistical moment.

Abstract: Tools and techniques for estimating and/or predicting a patient's current and/or future blood pressure. In some cases, the tools will analyze physiological data captured from the patient against a model of blood pressure values to estimate/predict the patient's blood pressure value. In particular cases, derived parameters, such as a patient's compensatory reserve index (“CRI”) can be analyzed against such models, while in other cases, data captured from sensors can be directly analyzed against such models.

Abstract: An implantable medical device system and associated method receive a signal from an implantable sensor operatively positioned relative to a vein, the signal being responsive to changes in a diameter of the vein. A diameter of the vein is determined in response to the sensor signal and used in estimating central venous pressure (CVP).

Abstract: System for indicating a possibility a cardiac tamponade occurring in a patient, comprising: —a right atrium pressure sensor, configured for measuring a right atrium pressure in a right atrium of the patient; —an intra pericardial pressure sensor, configured for measuring an intra pericardial pressure in a portion of an intra-pericardial space of the patient; —a processing device that is operatively connected to the pressure sensors, is provided with a predetermined statistical distribution of pressure versus tamponade probabilities, and is configured for: —determining a trans-mural pressure difference between the right atrium pressure and the intra pericardial pressure; —comparing the trans-mural pressure difference with the statistical distribution, and —indicating the possibility of cardiac tamponade occurrence, based on the trans-mural pressure difference comparison.

Abstract: A pressure sensing medical device may include a guidewire including a tubular member having a lumen, the tubular member being translatable between a generally straightened position and a deflected position, and a pressure sensor attached at a distal end of a fiber optic extending within the lumen, the pressure sensor being disposed within a distal portion of the tubular member. The pressure sensor may include a pressure-sensitive membrane disposed on a distal end thereof. The pressure sensor may include one or more contact members capable of providing a contact point between the contact member and an inner surface of the tubular member when in the deflected position, the contact point being axially spaced apart from the membrane along a longitudinal axis of the pressure sensor.

Abstract: Disclosed is a system that includes a signal acquisition circuit to acquire a cuff pressure signal using an inflatable cuff, and to generate an oscillometric signal from the cuff pressure signal. The system also includes a user interface to enter one or more patient-specific detection threshold values, a memory to store the cuff pressure signal, the oscillometric signal, and the one or more patient-specific detection threshold values. The system also includes a microprocessor operatively coupled to the signal acquisition circuit, the user interface, and the memory. The microprocessor includes at least one algorithm to use the cuff pressure signal, the oscillometric signal, and the entered one or more patient-specific detection threshold values to calculate patient-specific readings of at least one of mean arterial pressure, systolic blood pressure and diastolic blood pressure. Related apparatus, systems, methods and/or articles are described.

Abstract: Embodiments of the present disclosure are configured to assess the severity of a blockage in a vessel and, in particular, a stenosis in a blood vessel. In some particular embodiments, the devices, systems, and methods of the present disclosure are configured to assess the severity of a stenosis in the coronary arteries without the administration of a hyperemic agent. In some embodiments, the devices, systems, and methods of the present disclosure are configured to assess a vessel by automatically correcting for drift in the equipment utilized to obtain measurements related to the vessel.

Abstract: Techniques are provided for estimating left atrial pressure (LAP) or other cardiac performance parameters based on measured conduction delays. In particular, LAP is estimated based interventricular conduction delays. Predetermined conversion factors stored within the device are used to convert the various the conduction delays into LAP values or other appropriate cardiac performance parameters. The conversion factors may be, for example, slope and baseline values derived during an initial calibration procedure performed by an external system, such as an external programmer. In some examples, the slope and baseline values may be periodically re-calibrated by the implantable device itself. Techniques are also described for adaptively adjusting pacing parameters based on estimated LAP or other cardiac performance parameters. Still further, techniques are described for estimating conduction delays based on impedance or admittance values and for tracking heart failure therefrom.

Abstract: A transducer interface system/method allowing conversion from an analog sensor input to a standardized analog output interface is disclosed. In some preferred embodiments the system/method permits a fiber optic pressure sensor to be interfaced to a standard patient care monitor (PCM) system using standardized Wheatstone Bridge analog interface inputs. Within this context the Wheatstone Bridge sensed output is defined by stimulus from the PCM and modulation of bridge element values by the conditioned output of an analog pressure sensor. The use of analog-to-digital-to-analog conversion in this transducer interface permits retrofitting of PCM devices having analog Wheatstone Bridge inputs with advanced patient monitoring sensors without the need for specialized modifications to the baseline PCM data collection framework. Methods disclosed herein include techniques to connect arbitrary types/numbers of analog sensors to traditional PCM systems without the need for PCM system hardware/software modifications.

Abstract: Intravascular diagnosis apparatus and methods are disclosed. In one aspect of the disclosed technology, a intravascular diagnosis apparatus includes a monitoring guidewire and a display unit. The monitoring guidewire includes a core wire and a sensor disposed in a distal region of the core wire. The display unit includes a processor and a display screen, and is capable of receiving communication from the monitoring guidewire. The display unit is configured to perform computations using the processor based on communications received from the monitoring guidewire and is configured to display information on the display screen based on the computations. The display unit can be configured to be disposed after a predetermined number of uses or after a predetermined duration of use.

Abstract: A device and method for subcutaneously implanting an identification chip into a domestic animal, the identification chip becoming relatively immobile once implanted.

Abstract: According to one embodiment, a tissue penetrating device includes an elongate shaft having a proximal end, a distal end, and a lumen extending there between. A first needle is disposed within the lumen of the elongate shaft and is extendable therefrom between a first configuration and a second configuration. In the first configuration, the first needle is disposed within the elongate shaft's lumen and is substantially aligned with an axis of the lumen. In the second configuration, the first needle extends distally of the elongate shaft's distal end and bends away from the lumen's axis. A second needle is disposed within a lumen of the first needle and is extendable therefrom when the first needle is positioned in the first configuration and when the first needle is positioned in the second configuration. The second needle may be extended from the first needle to penetrate tissue of a patient.

Abstract: A cardiac pressure monitoring device includes a fixation member defining a central opening to facilitate slidably positioning the fixation device about a pacemaker lead wire. At least one sensor is coupled to the fixation member. The at least one sensor is configured to sense a physical, chemical, and/or physiological parameter within a cardiac chamber.

Abstract: A system and method for treating congestive heart failure in a patient, including: implanting at least one pressure sensor in a desired location within the patient; providing an ex-vivo interrogation system and monitoring system that can be configured to optionally affect at least one of: selectively energizing the at one pressure sensor, receiving a return or output signal from the at one pressure sensor, processing the return signal, and displaying processed data derived from the at least one pressure sensor to a physician. The system and method also includes deriving diagnostic and treatment information from the processed data and sending diagnostic and treatment information to the patient.

Abstract: Devices, systems, and methods to determine fractional flow reserve. At least one method for determining fractional flow reserve of the present disclosure comprises the steps positioning a device comprising at least two sensors within a luminal organ at or near a stenosis, wherein the at least two sensors are separated a predetermined distance from one another, operating the device to determine flow velocity of a second fluid introduced into me luminal organ to temporarily displace a first fluid present within the luminal organ, and determining fractional flow reserve at or near the stenosis based upon the flow velocity, a mean aortic pressure within the luminal organ, and at least one cross-sectional area at or near the stenosis. Devices and systems useful for performing such exemplary methods are also disclosed herein.

Abstract: An implantable medical device, such as a sensor for monitoring a selected internally detectable physiological parameter of a patient, is attached to a fixation member that is deployable within the patient to position and orient the sensor to enable it to perform its function. The fixation member may be configured to lie in a single plane when deployed or may be tubular in shape. The attachment of the housing and fixation member includes providing the fixation member with a linear attachment strut that is non-circular in cross section and providing the housing with external members that define an elongate channel, non-circular in cross section and receptive to the attachment strut. The attachment strut can be inserted transversely into the channel and the external member can be crimped over the strut to secure the housing and fixation member together.

Abstract: A medical device of the type used for assisting a user in manually delivering repetitive therapy to a patient (e.g., chest compressions or ventilations in cardiac resuscitation), the device comprising a feedback device configured to generate feedback cues to assist the user in timing the delivery of the repetitive therapy, at least one sensor or circuit element configured to detect actual delivery times, at which the user actually delivers the repetitive therapy, and a processor, memory, and associated circuitry configured to compare the actual delivery times to information representative of desired delivery times to determine cue times at which the feedback cues are generated by the feedback device.

Abstract: An injection system for injecting an injectate fluid into a blood vessel of the patient and for carrying out a blood pressure measurement of a patient. The injection system includes a catheter tube having a first end for penetrating the blood vessel of the patient, and a pressure sensor which is arranged close to a second end of the catheter tube and can sense a pressure of a liquid in the catheter tube as an indication of the blood pressure of the patient.

Abstract: Provided herein are methods and systems for the treatment of cardiovascular conditions, including pulmonary hypertension (PH), in subjects that are being treated with a treatment regimen that includes a phosphodiesterase-5 (PDE-5) inhibitor.

Abstract: Sensor guide wire for intravascular measurements of physiological variables in a living body or of external signals, which sensor guide wire has a proximal region, a distal sensor region and a tip region, the sensor guide wire comprises a core wire having a longitudinal axis parallel to the longitudinal axis of the sensor guide wire, and a sensor element arranged in the distal sensor region, the sensor element has a sensitive portion for measuring the physiological variable and to generate a sensor signal in response to said variable. The sensor element has an essentially planar main surface and has its maximal extension in the plane of the main surface, and a thickness perpendicular to the plane of the main surface, wherein the sensor element is arranged in an essentially perpendicular relation to said core wire with regard to the planar main surface of the sensor element.

Abstract: Embodiments of the present disclosure are configured to collect multi-modality medical data from a patient. In some embodiments, a method includes acquiring heartbeat data from the patient using a heart-monitoring device, the heartbeat data identifying a first cardiac cycle of the patient and selecting a diagnostic window within the first cardiac cycle of the patient, wherein the diagnostic window encompasses only a portion of the first cardiac cycle of the patient. The method also includes acquiring first medical data from the patient during the diagnostic window using a first medical device, the first medical data being associated with a first medical modality and acquiring second medical data from the patient during the diagnostic window using a second medical device, the second medical data being associated with a second medical modality different than the first medical modality.

Abstract: The invention is a method for calibrating an intravascular pressure sensor at the point of use. By using data from a secondary pressure measurement device, e.g., an automated aortic pressure monitor, the pressure sensor can be easily calibrated over a range of temperatures and pressures relevant to the patient. Accordingly, an intravascular pressure sensor can be calibrated without undergoing a factory calibration. Additionally, in the event that the calibration is lost, the sensor can be recalibrated.

Abstract: The present disclosure relates to devices, systems, and methods for evaluating and preserving arteriovenous access sites. More particularly, the present disclosure relates to a sensor wire that is sized, shaped, and configured to pass through a delivery instrument to measure pressure and flow within and around an AV access site, thereby indicating the impact of the arteriovenous access site on the blood flow to the surrounding vasculature and tissues in real time. Also, the present disclosure relates to a therapeutic system comprising a combination pressure-flow sensor wire, a balloon catheter with imaging capabilities, and a computer system to allow the user to evaluate the blood flow and blood pressure within and around an AV access site in real time, diagnose the presence of complications associated with arteriovenous access sites, treat such complications, and assess the effectiveness of treatment both during and after treatment.

Abstract: The invention generally relates to sensing guidewires with a centering element and methods of use thereof. In certain aspects, guidewires of the invention include a core member sized to fit within a vessel. A sensor is coupled to the core member. A centering element including a retracted and deployed configuration that is coupled to the core member such that upon deployment of the centering element, the sensor on the core member is located within a center of a lumen.

Abstract: The device and method of the invention generally relate to a system and method for percutaneous delivery, implantation and securement of an anchor at a target site. The system comprises an anchor having a bridge, a first stabilizer having a crimped state and a deployed state, a second stabilizer having a crimped state and a deployed state, and a positioning arm. The system may further comprise a cannula, pushrod, and sheath. The system permits the deposit of an anchor at a target location in the body by utilizing a controlled amount of force. The anchors and methods are particularly well-suited to implantation within the body of a living animal or human to monitor various physiological conditions.

Abstract: The invention generally relates to systems and methods for determining coronary flow reserve (CFR). The invention provides systems and methods for determining coronary flow reserve using a flow reserve index obtained at rest and during hyperemia. One flow reserve index obtained under the two conditions can be used to compute coronary flow reserve. The difference between the resting value and the hyperemic value of the index correlates to a coronary flow reserve value.

Abstract: Embodiments of the present disclosure are configured to assess the severity of a blockage in a vessel and, in particular, a stenosis in a blood vessel. In some particular embodiments, the devices, systems, and methods of the present disclosure are configured to provide FFR measurements over a length of a vessel of interest in a small, compact device that integrates with existing proximal and distal pressure measurement systems and does not require a separate power source.

Abstract: This invention relates to an implantable device for a physiologic sensor, comprising an implantable expandable anchor, a bridge on which the sensor is secured, as well as an optional adapting ring. The invention also relates to a method of monitoring bodily functions using the anchor and sensor. The anchor is compressed and the bridge assumes an elongated shape during delivery to a target lumen. Upon deployment at the target site, the anchor expands and the bridge bows into the interior lumen of the expanded anchor, distancing the sensor from the vessel wall. This invention also relates to a method of manufacturing said device and a method of implanting a sensor.

Abstract: The present invention generally relates to methods for detecting endoleaks associated with EVAR procedures using physiological measurements. The method can involve the taking of functional measurement data in the vicinity of a stent-graft delivered as part of the EVAR procedure and determining the presence of an endoleak based on such data.

Abstract: An intravascular sensor delivery device for measuring a physiological parameter of a patient, such as blood pressure, within a vascular structure or passage. In some embodiments, the device can be used to measure the pressure gradient across a stenotic lesion or heart valve. For example, such a device may be used to measure fractional flow reserve (FFR) across a stenotic lesion in order to assess the severity of the lesion. The sensor delivery device has a distal sleeve configured to pass or slide over a standard medical guidewire. Some distance back from the sensor and distal sleeve, the device separates from the guidewire to permit independent control of the sensor delivery device and the guidewire. The sensor delivery device can be sized to pass over different sizes of guidewires to enable usage in coronary and peripheral arteries, for example.

Abstract: The present disclosure involves a medical device. The medical device includes an elongate cable assembly having a distal connector, a proximal connector, and a cable body coupling the proximal and distal connectors. The distal connector is configured for coupling with a diagnostic medical device. The proximal connector is configured for coupling with a medical measurement system. An electronic component is located inside the distal connector or the associated cable housing. The electronic component includes an analog-to-digital converter (ADC) and a microprocessor. The ADC is configured to receive medical data gathered by the diagnostic medical device and convert the medical data into digital signals. The microprocessor is coupled to an output of the ADC and configured to process the digital signals into a format that is readable by the medical measurement system.

Abstract: Cardiac valve events are monitored by recording a left atrial pressure (LAP) representing signal using an implantable pressure sensor (50). The LAP signal is processed in order to generate a derivative LAP signal representative of the first time derivative of the LAP signal. The opening of the aortic valve of the heart is then identified to coincide in time with a minimum in the derivative LAP signal following ventricular depolarization in a cardiac cycle.

Abstract: An apparatus for measuring distensibility of a vessel, lumen or sphincter includes a balloon catheter having a balloon located adjacent a distal end of a catheter for inserting in, for example, the sphincter, the distensibility of which is to be determined. The balloon is inflated to respective first and second pressures to distend the sphincter to respective first and second transverse cross-sectional areas which are measured. The first and second pressures are selected so that the relationship between the pressure and the cross-sectional area of the sphincter is linear. The distensibility of the sphincter is determined as a distensibility index, which is the value of c from the equation of a line y=mx+c containing the values of the first and second pressures and areas, where x represents pressure and y represents area.

Abstract: An implantable medical device system and associated method receive a signal from an implantable sensor operatively positioned relative to a vein, the signal being responsive to changes in a diameter of the vein. A diameter of the vein is determined in response to the sensor signal and used in estimating central venous pressure (CVP).

Abstract: Systems, devices, and methods for obtaining fractional flow reserve in the presence of a catheter. In a method of determining a fractional flow reserve in the presence of a catheter, the method comprises the steps of obtaining measurements of an inner luminal organ diameter proximal to, at, and distal to a stenosis and a length of the stenosis, obtaining a pressure drop measurement at the stenosis, calculating a volumetric flow of fluid through the inner luminal organ at the stenosis, and determining a stenotic pressure drop at the stenosis corresponding to dimensions of the guidewire as a function of the calculated volumetric flow of fluid through the inner luminal organ at the stenosis, wherein the stenotic pressure drop is indicative of a fractional flow reserve at or near the stenosis.