Intravascular Pressure and Flow Data Diagnostic Systems, Devices, and Methods
In part, the disclosure relates to computer-based methods, devices, and systems suitable for performing intravascular data analysis and measurement of various types of data such as pressure and flow data. The disclosure relates to probes and methods suitable for determining an event in a cardiac cycle such as flow threshold such as a peak flow, a fraction thereof, other intravascular parameters or a point in time during which peak flow or a change in one of the perimeters occurs. An exemplary probe includes one or more of a pressure sensor, a resistor, a flow sensor and can be used to generate diagnostic data based upon measured intravascular and other parameters. In part, the disclosure relates to methods and systems suitable for determining a coronary flow reserve value in response to one or more of intravascular pressure and flow data or data otherwise correlated therewith.
1 . A method of intravascular pressure and flow monitoring comprising:
measuring a plurality of intravascular blood flow values and a plurality of blood pressure values during one or more heartbeats using one or more sensors;
determining a flow threshold for one or more heartbeats using one or more of the plurality of intravascular blood flow values;
determining a proximal pressure value and a distal pressure value during the flow threshold;
calculating a first diagnostic parameter based on the proximal pressure value and the distal pressure value during the flow threshold for one or more heartbeats; and
displaying, on a user display, the first diagnostic parameter for one or more heart beats or a second diagnostic parameter determined using the first diagnostic parameter.
2 . The method of claim 1 , wherein:
the first diagnostic parameter is a pressure difference of the proximal pressure value minus the distal pressure value.
3 . The method of claim 1 , wherein:
the first diagnostic parameter is a pressure ratio of the distal pressure value over the proximal pressure value.
4 . The method of any of claims 1 - 3 , wherein:
the proximal pressure value is a proximal pressure value measured relative to a stenosis.
5 . The method of any of claims 1 - 3 , wherein:
the proximal pressure value is an aortic pressure value.
6 . The method of claim 1 , wherein:
the first diagnostic parameter and the second diagnostic parameter are selected from the group consisting of aortic pressure, distal pressure, a flow velocity, a pressure value, a maximum flow, a minimum flow, a relative extremum of flow, a fractional flow reserve (FFR) value, a coronary flow reserve (CFR) value, a coronary flow velocity reserve (CFVR) value, an instantaneous flow reserve (IFR) value, and an index of myocardial resistance (IMR) value.
7 . The method of claim 1 , wherein:
the flow threshold is selected from the group consisting of a maximum flow during a cardiac cycle, a relative extremum flow value during a cardiac cycle, a fraction of the maximum flow during a cardiac cycle, a hyperemic max flow value, and a non-hyperemic flow value.
8 . The method of claim 1 wherein:
measuring a plurality of intravascular blood flow values and a plurality of blood pressure values comprises:
measuring a first electrical signal associated with a first resistor and a second resistor disposed in a blood vessel,
measuring a second electrical signal associated with the second resistor disposed in the blood vessel,
determining one or more of the blood pressure values using one or more of the first and second electrical signals;
determining one or more blood temperature values for the blood vessel using one or more of the first and second electrical signals; and
determining the plurality of intravascular blood flow values for the blood vessel using one or more of the first and second electrical signals.
9 . The method of claim 1 , wherein:
calculating the first diagnostic parameter comprises calculating an average of pressure ratios or pressure differences for a plurality of cardiac cycles per a determined flow threshold for each cardiac cycle.
10 . The method of claim 1 , wherein the first diagnostic parameter is a mean of pressure ratios for a plurality of cardiac cycles or a mean of pressure differences for a plurality of cardiac cycles.
11 . The method of claim 10 , wherein:
measuring the plurality of intravascular blood flow values comprises receiving electrical signals correlated with temperature changes of an intravascular thermoconvection device in thermal communication with a blood vessel, the temperature changes correlated with changes in a flow during one or more cardiac cycles; and
the flow threshold is a peak blood flow value from among the plurality of intravascular blood flow values.
12 . The method of claim 10 further comprising:
calibrating an intravascular data collection system, which comprises:
setting a baseline value for a distal pressure signal measured by an intravascular thermoconvection device,
positioning the intravascular thermoconvection device at a delivery catheter opening,
setting a baseline value of a temperature signal measured by the intravascular thermoconvection device prior to advancing the intravascular thermoconvection device into a vascular system,
advancing the intravascular thermoconvection device to a position distal to the catheter opening,
equalizing an intravascular thermoconvection device pressure signal (Pd) to an aortic pressure (Pa) signal,
calibrating a temperature signal of the intravascular thermoconvection device when the intravascular thermoconvection device is in a measurement location of interest, and
sampling the intravascular thermoconvection device to obtain intravascular thermoconvection device pressure signal (Pd) values and thermoconvection device temperature values.