Abstract: A catheter for retrograde orientation in a blood flow is used to determine the blood flow rate by thermodilution measurements. The determination of the blood flow rate accommodates injectate induced thermal influences on a dilution thermal sensor, wherein the thermal influences can occur prior to introduction of the injectate into the blood flow.

Abstract: Devices, systems and methods by which the real or apparent renovascular perfusion and intrarenal pressure may be selectively and controllably increased. By selectively and controllably increasing renovascular perfusion and interstitial hydrostatic pressure when the heart is unable to pump sufficient blood or when renal perfusion is suboptimal, the present invention reduces or reverses neurohormonal activation and fluid retention, and thereby minimizes their deleterious effects on the heart, vasculature, kidneys and other body systems.

Abstract: A catheter for retrograde orientation in a blood flow is used to determine the blood flow rate by thermodilution measurements. The determination of the blood flow rate accommodates injectate induced thermal influences on a dilution thermal sensor, wherein the thermal influences can occur prior to introduction of the injectate into the blood flow.

Abstract: A signal conditioning device is disclosed that interfaces a variety of sensor devices, such as guide wire-mounted pressure sensors, to physiology monitors. The signal conditioning device includes a processor for controlling sensor excitation and signal conditioning circuitry within the signal conditioning device. The processor also supplies signals to an output stage on the signal conditioning device representative of processed sensor signals received by a sensor interface of the signal conditioning device. Power for the signal conditioning device processor is supplied by an excitation signal received from a physiology monitor that drives the output stage. In addition, a temperature compensating current source provides an adjustment current to at least one of a pair of resistive sensor elements to compensate for differences between temperature change upon the pair of resistive sensor elements, thereby facilitating nullifying temperature effects upon the resistive sensor elements.

Abstract: A technique for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.

Abstract: A technique for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.

Abstract: The system for measuring the velocity of blood flow in the coronary artery, comprises a guidewire adapted for coupling with conventional coronary intervention devices and has two or more temperature sensors mounted at equally spaced intervals along its distal segment. With the guidewire positioned at a point of interest in the artery, a steady infusion of a room-temperature saline solution is injected into the blood stream at the coronary ostium, lowering the local blood temperature slightly. Warmer pulsatile flow from the aorta mixes with this inflow, producing phasic temperature oscillations that are detected in sequence by the guidewire's temperature sensors. The elapse of time between the detected phase shifts indicates the velocity of the flowing blood. An external monitoring system connected to the guidewire provides instant read-outs of this value, which may be secured before, during and after intervention procedures, or after induced coronary hyperemia to determine coronary reserve.

Abstract: A computer system (104) is connected to an injection means (107) to inject at a first place (101 ) a bolus warmer or colder than patient's blood. The travelling temperature deviation thus introduced to the patient's vascular system (103) passes the pulmonary circulation (111), where an extravascular thermovolume (112) may be present. When the temperature deviation reaches the second place (102), where blood temperature is measured by a sensor device (117) connected to the computer system (104), it is recorded as Thermodilution Curve (15), from which the computer system (104) determines an extravascular thermovolume estimate. Depending on that result the computer system (104) calculates a new amount of bolus to be injected by the injection means (107). The higher the extravascular thermovolume estimate, the higher the new amount of bolus.

Abstract: Apparatus for ascertaining cardiac output of the heart of a patient comprising a control and display module. A venous probe is inserted into a vein in the forearm of the patient and is coupled into the control and display module and provides an electrical signal representing the dissolved oxygen in the venous blood. An arterial probe is inserted into an artery in the forearm of the patient and is coupled into the control and display module and provides an electrical output signal representing the dissolved oxygen in the arterial blood. The control and display module has a visible display that provides a continuous in vivo cardiac output that utilizes an arterial venous oxygen differential equation which includes an adjustment factor for adjusting for venous blood being sampled rather than mixed venous blood in the pulmonary artery of the patient.

Abstract: Devices and methods for detecting vulnerable plaque within a blood vessel are disclosed. A catheter in accordance with the present invention includes an elongate shaft having a proximal end, a distal end, and an outer surface. At least one temperature sensor is disposed proximate to the distal end of the elongate shaft. In one preferred embodiment, the at least one temperature sensor is adapted to contact an inner surface of the blood vessel. In another preferred embodiment, at least one temperature sensor is disposed within a channel defined by a body member that is disposed about the elongate shaft.

Abstract: A device for measuring physiological parameters within an aneurysm sac that has been excluded from blood flow by an endoprosthesis. The device is comprised of at least two sensors, one placed in the aneurysm sac and another in a systemic artery. A differential between the readings of the two sensors can then be calculated, making the device easily calibrated in vivo and insensitive to changes in atmospheric pressure.

Abstract: The present invention provides a method and apparatus for measuring the blood flow rate within an A-V shunt via indicator dilution techniques. Unknown flow resistance within the A-V shunt are addressed by adjusting a measured flow rate to provide a flow rate within a predetermined margin of error. The calculated flow rate can be rejected based upon flow conditions of the introduced indicator. Different indicator introduction rates can be used to enhance accuracy of the measured flow. The indicator flow path can include a flow restrictor to limit the flow rate of the indicator to below a predetermined value.

Abstract: The system for measuring coronary blood flow velocity, comprises a guidewire shaft of a size suitable for “over the wire” placement of intervention devices in a coronary artery, with several equally spaced thermal sensors mounted in sequence, along its extreme distal segment, to detect and report thermal changes to an external monitoring apparatus. When the guidewire has been inserted at a segment of interest in the coronary artery, a steady infusion of room temperature saline or other suitable miscible infusion is introduced for 10 to 15 seconds at the ostium of the coronary artery. The infusion generates a thermal indicator by lowering the basal coronary blood by a fraction of a degree centigrade. The phasic nature of the relatively warmer coronary flow from the aorta, with its large diastolic and small systolic components, modulates the lowered temperature level in a cyclical, wavy pattern that simulates rectified sine waves.

Abstract: A thermodilution catheter having a heating filament which is fabricated so as to be thin and flexible enough to avoid contact with the patient's blood. The heating filament is either inserted in a preformed catheter lumen, incorporated into a wall of the catheter body itself, or wrapped around the catheter body wall and surrounded by an external sheath. Generally, the covering of the heating filament is minimally thin so as to allow the heat from the heating filament to be transferred to the surrounding blood and to minimally increase the overall cross-sectional area. Since the heating filament does not directly touch the patient's blood, the outer surface may be made smooth so as to prevent inducement of blood clots. In addition, the heating filament may be maintained at a safe temperature by forming the heating element of a flexible material having a high temperature coefficient of resistance, low thermal capacitance and high thermal conductivity.

Abstract: A method and apparatus determines continuously mean cardiac output by measuring the arterial pressure e.g. at a finger and calculating therefrom the mean arterial pressure and the time constant of the arterial system (in diastole). Compliance values are provided from a table. Mean cardiac output is then the product of mean arterial pressure and compliance divided by the time constant. Changes in cardiac output can be used for diagnostic purposes. A pressure cuff or pressure tonometer can be used to measure the arterial pressure with a microcomputer providing the necessary calculations.

Abstract: A signal conditioning device is disclosed that interfaces a variety of sensor devices, such as guide wire-mounted pressure sensors, to physiology monitors. The signal conditioning device includes a processor for controlling sensor excitation and signal conditioning circuitry within the signal conditioning device. The processor also supplies signals to an output stage on the signal conditioning device representative of processed sensor signals received by a sensor interface of the signal conditioning device. Power for the signal conditioning device processor is supplied by an excitation signal received from a physiology monitor that drives the output stage.

Abstract: The present invention relates to intravascular pressure measurement based devices and methods determining clinical parameters related to stenosis severity for improved clinical diagnosis and treatment of cardiovascular disease in blood vessels or tubular conduits. More specifically, the invention provides methods for the determination of the clinically significant well known Coronary Flow Reserve (CFR) parameter-previously acquired by velocity measurement devices. In addition Coronary Flow Reserve in the same vessel without stenosis may be estimated and uses to select the necessary medical treatment. Additional pressure based clinical parameters, Diastole to Systole Velocity Ratio (DSVR) and Fractional Flow Reserve (FFR) in stenotic blood vessel during intervention (using only pressure measurements across stenosis) may also be calculated simultaneously, with the same set of interventional devices. Correlation of CFR with these parameters (e.g.

Abstract: The present invention relates to a system for measuring at least one physical parameter in a place in a patient's body to which a medical probe has access, comprising a medical probe (1) equipped with a sensor of said parameter and means for emitting an electrical signal that represents said parameter and that is received by the sensor, to a data processing device outside the patient's body.

Abstract: Microspheres are permanently marked with non-radioactive stable isotopes of elements suitably detected by neutron activation analysis. The marked microspheres are suitable to permanently label diverse things. For example, families of stable-multiple-isotope-marked microspheres injected into an animal become lodged by the circulating blood within selected tissues of an animal during blood flow analysis experimentation. Absolute and relative abundances of these stable-isotope-marked microspheres residing within harvested tissues are readily accurately automatically measured in situ within the harvested tissue samples by neutron activation analysis. The quantitatively measured abundance of the isotopes, and associated microspheres, are accurately indicative of the former flow of blood containing the microspheres to the tissue.

Abstract: A central venous cather (1) is placed in the vena cava superior (2) and equipped with a heating coil (3) for emitting heat pulses in the immediate proximity of the distal end (5) of the catheter (1) in order to introduce travelling temperature deviations to the patient's circulation. The power transferred to the blood stream during emission of each heat pulse represents an input signal for modified thermodilution measurements. Each travelling temperature deviation is detected as a system response corresponding to an input signal, when it reaches an arterial catheter (14) which additionally comprises a pressure sensor (17) for measuring the local blood pressure in the arteria femoralis (16) as a function of time.

Abstract: A sensor is disclosed, for implantation within a blood vessel to monitor an analyte in blood. In one embodiment, the analyte is glucose. A signal indicative of glucose level is transmitted to an external receiver. The signal may also be used to drive an internal or externally worn insulin pump. Methods are also disclosed.

Abstract: A system for rehabilitative therapy including a muscle contraction or body movement sensor coupled to a converter or interface, which is in turn coupled to a computer input port. The system includes software running on the computer for obtaining patient data, obtaining real time sensor data, storing sensor historical data, and outputting the sensor data as gamepiece movement or position in an executing computer game. In one embodiment, joint flexion and extension are required to move a cursor right and left. In another embodiment, joint rotation is required to move a cursor up and down. In one system the interface outputs data to a computer serial port. In one system, the relative sensor position is reflected in gamepiece position. In another system, the sensor position relative to a threshold is reflected in gamepiece movement after the body sensor passes a threshold in muscle contraction or body movement.

Abstract: A medical monitoring apparatus designed to be implanted in the vascular system is capable of sensing and transmitting via a telemetry link to an external monitor both pressure and temperature information. An internally or externally powered microcircuit component is supported on a stent-like structure and adapted to be placed in the vascular system. Placement in the ventricular septum permits measurement of pressure and temperature in the left ventricle without introducing thrombus generating materials in the left ventricle.

Abstract: The present invention relates to a method for determining the cardiac output of a subject by thermodilution measurements by providing a predetermined amount of thermal indicator in a blood vessel with the thermal indicator having a temperature different from the temperature of subject's blood, thus exhibiting an indicator temperature difference. By measuring the temperature of subject's blood at a second place downstream the cardiac output (CO) and the extravascular thermovolume can be determined as a function of the time for the thermodilution curve. As a function of the thermodilution curve the measurements of the amount of thermal indicator and/or thermal indicator volume temperature difference are adjusted to provide a more accurate determination of cardiac output.

Abstract: Systems are methods described for calculating, in real-time, various oxygenation parameters including total oxygen transport, mixed venous blood oxygen tension and mixed venous blood oxyhemoglobin saturation in a patient. The system preferably uses a computer, an arterial pressure line and a blood chemistry monitor to assist a physician in accurately determining when to give a patient a blood transfusion or otherwise alter the clinical management of that patient.

Abstract: A thermodilution catheter having a heating filament which is fabricated so as to be thin and flexible enough to avoid contact with the patient's blood. The heating filament is either inserted in a preformed catheter lumen, incorporated into a wall of the catheter body itself, or wrapped around the catheter body wall and surrounded by an external sheath. Generally, the covering of the heating filament is minimally thin so as to allow the heat from the heating filament to be transferred to the surrounding blood and to minimally increase the overall cross-sectional area. Since the heating filament does not directly touch the patient's blood, the outer surface may be made smooth so as to prevent inducement of blood clots. In addition, the heating filament may be maintained at a safe temperature by forming the heating element of a flexible material having a high temperature coefficient of resistance, low thermal capacitance and high thermal conductivity.

Abstract: A blood vessel imaging system includes a measuring light source which emits a measuring light beam. An optical heterodyne detection system consists of an optical system which splits the measuring light beam into a first light beam traveling to impinge upon an organism and a second light beam traveling not to impinge upon the organism and combines the second light beam with the first beam emanating from the organism into a combined light beam, a frequency shifter which causes the first and second light beams to have frequencies different from each other, and a beat component detector which detects beat components of the combined light beam. A band-pass filter detects, out of the beat component detection signal output from the beat component detector, off-centered components in a frequency band deviated from the center frequency of the beat component detection signal by a predetermined width.

Abstract: A thermodilution catheter having a heating filament which is fabricated so as to be thin and flexible enough to avoid contact with the patient's blood. The heating filament is either inserted in a preformed catheter lumen, incorporated into a wall of the catheter body itself, or wrapped around the catheter body wall and surrounded by an external sheath. Generally, the covering of the heating filament is minimally thin so as to allow the heat from the heating filament to be transferred to the surrounding blood and to minimally increase the overall cross-sectional area. Since the heating filament does not directly touch the patient's blood, the outer surface may be made smooth so as to prevent inducement of blood clots. In addition, the heating filament may be maintained at a safe temperature by forming the heating element of a flexible material having a high temperature coefficient of resistance, low thermal capacitance and high thermal conductivity.

Abstract: A system and method obtains a respiration parameter of an animal or human, such as respiratory rate, from a blood pressure, volumetric blood flow, blood velocity or stroke volume signal from a sensor for the animal or human. Specifically, the signal is processed to develop an amplitude versus time waveform. A sequence of selected features derived from individual cardiac cycles of the amplitude versus time waveform over a selected time interval are extracted from the developed amplitude versus time waveform. A mathematical model is fitted to the extracted sequence of selected features to yield a fitted mathematical model. The physiologic parameter information is computed from the fitted mathematical model.

Abstract: A method for the measurement of cardiac output in a patient in which the arterial blood pressure waveform of a patient from a blood pressure monitoring device over a period of time is subjected to various transformations and corrections, including a Fourier analysis in order to obtain the modulus of the first harmonic. The nominal stroke volume is then determined from the first harmonic and data relating to the arterial blood pressure and heart rate. The nominal cardiac output is then obtained from the nominal stroke volume.

Abstract: A system for sensing a characteristic of fluid flowing to or from the body of a human or animal comprising a conduit having a first end adapted to be outside the body, a second end adapted to be received within the body, and a flow passage through which fluid can flow between the first and second ends and a probe including a sensor for sensing a characteristic of the fluid. The probe is mounted on the conduit with the sensor in the flow passage. The sensor is isolated from the fluid flowing in the flow passage.

Abstract: In use of at least two electrode pairs for the generation of a difference signal that corresponds to the flow through a vein upstream and downstream of the connection of a venous duct to the vein, a first signal is generated that corresponds to the resistance over the first electrode pair, upstream of the connection of the venous duct to the vein, a second signal is generated that corresponds to the resistance over the second electrode pair, downstream of the connection of the venous duct to the vein, and the difference signal between the first and the second signal is then determined so that a regional blood flow through a person or an animal can be determined.

Abstract: Microspheres are permanently marked with non-radioactive stable isotopes of elements suitably detected by neutron activation analysis. The marked microspheres are suitable to permanently label diverse things. For example, families of stable-multiple-isotope-marked microspheres injected into an animal become lodged by the circulating blood within selected tissues of an animal during blood flow analysis experimentation. Absolute and relative abundances of these stable-isotope-marked microspheres residing within harvested tissues are readily accurately automatically measured in situ within the harvested tissue samples by neutron activation analysis. The quantitatively measured abundance of the isotopes, and associated microspheres, are accurately indicative of the former flow of blood containing the microspheres to the tissue.

Abstract: An apparatus for continuous cardiac output monitoring ascertains cardiac output by measuring the cross-sectional area of the vessel and the flow rate of fluid flowing through the vessel. The cross-sectional area is derived from the measured resistance within the vessel whereby a pair of signal electrodes injects a known electrical signal into the vessel and the resistance is derived from the known signal and the differential voltage between first and second measuring pairs of electrodes. Resistivity of the fluid is a component of the cross-sectional area derivation, and a temperature sensor is provided to allow for compensating for variations in resistivity with temperature. A velocity sensor is preferably of an optic fiber, Doppler shift type, and the accuracy of the velocity measurement is improved by focusing light emissions from the optic fiber(s) by either providing a Fresnel plate on the terminal end of the fiber or by forming the terminal end of the fiber in a generally conical shape.

Abstract: An esophageal probe useful for invasively monitoring the cardiac output of a patient generally comprises a chassis with an electrical cable extending from the proximal end of the chassis and with the cable terminating at an electrical plug configured for connection to a cardiac output monitor. The probe includes an electrode assembly configured to generate and transmit electrical signals that are indicative of the impedance variation of the thorax. The probe further includes a deployment device attached to the chassis for stabilizing the probe within the esophagus. The probe may also be configured to include other sensing devices, for example, a temperature measuring device and an acoustic monitor.

Abstract: A medical monitoring apparatus designed to be implanted in the vascular system is capable of sensing and transmitting via a telemetry link to an external monitor both pressure and temperature information. An internally or externally powered microcircuit component is supported on a stent-like structure and adapted to be placed in the vascular system. Placement in the ventricular septum permits measurement of pressure and temperature in the left ventricle without introducing thrombus generating materials in the left ventricle.

Abstract: Methods and devices are provided for assessing impairment of blood circulation in a patient, such as that in perfusion failure, by measurement of blood flow in the gastrointestinal tract or upper respiratory/digestive tract of the patient. The method comprises introducing a blood-flow sensor into the gastrointestinal tract or the upper respiratory/digestive tract of a patient, placing the sensor adjacent a mucosal surface therein, and measuring blood flow in adjacent tissue to determine blood flow in that tissue. The method may also involve measurement of PCO2 and/or pH in combination with the blood flow determination. The invention affords rapid measurement and detection of perfusion failure.

Abstract: The invention relates to a method for the correction of measured value falsifications in invasive pressure measurements with a fluid-filled system, in which the measured pressure is passed via the fluid-filled system to an external pressure transducer, which converts the pressure signal into an electrical signal. To provide a method and a device for invasive pressure measurement with fluid-filled systems which are improved with respect to the correction of measured value falsifications, are cost-effective and versatile in their use, the electrical signal is passed through an analog/digital converter and the digitized signal is fed to a signal analyzing and processing unit, which operates on the basis of a digital Fourier analysis. Furthermore, a heartbeat-related or segmental analysis is carried out and the signal is combined with empirically determined correction data on the basis of the analysis.

Abstract: A method is disclosed for diagnosing, monitoring and treating cardiovascular pathologies. Among the hemodynamic parameters of interest are peripheral resistance, compliance, and cardiac (left ventricular) output. Peripheral resistance determined according to the present invention has been found to be a reliable indicator, not only of hypertension, but also of the cause of the hypertension. The determined peripheral resistance can be compared against a predetermined threshold value. This comparison helps to foster a diagnosis of a hypertensive condition.

Abstract: An intrabody implantable system for long-term, real time monitoring of at least one parameter associated with heart performance.

Abstract: Disclosed is a medical device for introduction into a patient's body, in particular into the patient's blood vessel, for measuring a physiological parameter. The medical device comprises means for coding the site of an application of the medical device in the patient's body and/or means for coding the effect of the site of an application of the medical device in the patient's body on the measurement of the physiological parameter.

Abstract: Methods and devices are provided for assessing impairment of blood circulation in a patient, such as that in perfusion failure, by measurement of blood flow in the gastrointestinal tract or upper respiratory/digestive tract of the patient. The method comprises introducing a blood-flow sensor into the gastrointestinal tract or the upper respiratory/digestive tract of a patient, placing the sensor adjacent a mucosal surface therein, and measuring blood flow in adjacent tissue to determine blood flow in that tissue. The method may also involve measurement of PCO2 and/or pH in combination with the blood flow determination. The invention affords rapid measurement and detection of perfusion failure.

Abstract: A system for sensing a characteristic of fluid flowing to or from the body of a human or a comprising a conduit having a first end adapted to be outside the body, a second end adapted to be received within the body, and a flow passage through which fluid can flow between the first and second ends and a probe including a sensor for sensing a characteristic of the fluid. The probe is mounted on the conduit with the sensor in the flow passage. The sensor is isolated from the fluid flowing in the flow passage.

Abstract: A technicue for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.

Abstract: A method of analyzing a signal representing a physical parameter to obtain information from said signal and to extrapolate information contained in said signal and/or to ignore an interfering component in part of said signal, said signal representing either only a first portion of a skew distribution, or a first portion of a skew distribution and a second portion containing an interfering component, in which the area of a skew distribution, preferably a lognormal distribution is measured. The method is particularly applicable to the measurement of cardiac output. Apparatus for carrying out the method is also disclosed.

Abstract: A technique for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.

Abstract: The pressure measuring guide wire comprises an elongated flexible shaft with a lumen extending therethrough. The lumen is surrounded by a wall forming the shaft and the distal portion of which is provided with slots for pressure medium entry. The distal portion has a thickness, greater than the thickness of the proximal area of the shaft. A coil surrounds the proximal area of the shaft to compensate the difference in kinking resistance between the proximal and distal areas of the shaft.

Abstract: A technique for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.

Abstract: Implantable apparatus for measuring a fluid flow in the body of a subject, including a stent, having a generally cylindrical radial outer wall and a central lumen. A flow parameter sensor is fixed to the stent, and measures a parameter relating to a rate of blood flow through the stent. A transmitter transmits signals responsive to the measured parameter to a receiver outside the body.

Abstract: The cardiac ejection fraction EF is estimated based on the parameters of a model of an indicator (such as thermal) dilution through the heart. A channel model is defined by an upstream indicator injector, such as a heater, positioned preferably in the right atrium/ventricle and a downstream indicator concentration sensor, such as a thermistor. The preferred model is a lagged normal transfer function, which has as one of its output parameters the indicator decay constant .tau. of the blood channel. The heart rate HR is also measured. The ejection fraction EF is then calculated continuously as EF=1-exp(-60/(.tau.*HR)). The cardiac output CO is also estimated in the model, preferably based on an estimate of the zero-frequency gain of the lagged normal transfer function. End diastolic volume EDV is then also calculated continuously as a function of CO, HR and EF.