Abstract: A method for temperature compensation is disclosed which comprises the excitation of sensors in a guide wire sensor assembly so as to produce two distinguishable signals. At least a component of at least one of the signals is representative of the cable resistance and can be used for compensation purposes. There is also provided an apparatus suitable for such measurements having temperature compensation circuitry. The compensation circuitry comprises circuitry for selectively and independently registering a resistance value for a passive resistor on the chip.

Abstract: This invention relates to a method and system for monitoring, determining by measurement and calculation and graphically displaying physiological variables related to blood pressure, wherein at least two physiological variables, arterial pressure (Pa) and distal coronary pressure (Pd), is detected by and derived from a guidewire-mounted pressure sensor. The Myocordial Fractional Flow Reserve (FFRmyo) is determined by calculating a ratio Pd/Pa from said measured physiological variables (Pa, Pd) and a graph is formed and displayed of the data resulting from said calculation. The invention also provides an Interactive graphical User Interface system for controlling the performance of and for displaying, in at least one screen on a display in a monitoring unit, intermediate and final results of said invented method.

Abstract: When a bolus dose of cold saline is injected into a catheter where a wire, carrying a sensor unit and electrical leads for signal transmission, is located, the lead resistance is affected by the cold saline thereby altering the resistivity. However, by countering this effect and measuring the change needed to affect this countermeasure, a resistance variation curve can be generated. An accurate starting point for the determination of a transit time can be derived from the curve. Using conventional flow measurement calculations with the accurate starting point yields a better understanding of the flow profile in an artery based on the transit time.