Devices, systems, and methods to determine fractional flow reserve

A method for determining a flow reserve within a luminal organ, the method comprising the steps of:

• introducing an impedance device into a lumen of a luminal organ at or near a stenosis;
• operating the impedance device to determine a flow velocity of a fluid within the luminal organ and to obtain conductance data useful to determine a cross-sectional area within the luminal organ;
• determining a cross-sectional area within the luminal organ using the conductance data;
• determining a pressure measurement indicative of the luminal organ using a data acquisition and processing system, wherein the pressure measurement is determined using the flow velocity and the cross-sectional area without the use of a pressure sensor;
• and
• determining, using the data acquisition and processing system, a flow reserve at or near the stenosis using the flow velocity, the cross-sectional area, and the pressure measurement.

A system for determining a flow reserve within a luminal organ, the system comprising:

• an impedance device comprising at least two sensors separated a predetermined distance from one another, the impedance device operable to (a) determine a flow velocity of a fluid within a mammalian luminal organ;
• and (b) obtain conductance data within the mammalian luminal organ useful to determine a cross-sectional area of the mammalian luminal organ, when at least part of the impedance device is positioned within the mammalian luminal organ;
• and
• a data acquisition and processing system coupled to the impedance device, the data acquisition and processing system configured to (a) determine the cross-sectional area using the conductance data obtained from the impedance device, (b) determine a pressure measurement within the mammalian luminal organ using the flow velocity and the cross-sectional area, without the use of a pressure sensor, and (c) determine a flow reserve at or near a stenosis within the mammalian luminal organ using the cross-sectional area, the flow velocity, and the pressure measurement.