Coronary Blood Flow Measurement Using Guide Wire Sensor
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Solution Overview
Problem
Current methods for measuring blood flow in individual coronary arteries are inadequate, as they cannot provide absolute values and are prone to variability, limiting their medical significance, especially for patients with coronary disease.
Innovation Solution
A method using a guide wire-mounted temperature sensor and infusion catheter for continuous thermodilution with a known indicator fluid, allowing for the calculation of absolute coronary blood flow and fractional flow reserve (FFR) values, which are essential for relating measured flows to normal values for a specific patient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a specially designed catheter is introduced into the coronary sinus for thermodilution measurements, then in vivo blood flow measurement is achieved, but the catheter's large outer diameter prevents its use in individual coronary arteries
Solution Approach 1:
The invention divides the measurement system into separate functional components: a guide catheter for access, a guide wire with temperature sensor for measurement, and a separate infusion device for indicator delivery. This segmentation allows each component to be optimized independently, enabling the sensor to be thin enough for coronary artery access while maintaining measurement capability
Solution Approach 2:
The guide wire with temperature sensor is nested within the guide catheter, and the infusion device is positioned through the guide catheter. This nested arrangement allows all components to access the coronary artery through a single puncture site while maintaining their individual functional integrity and appropriate dimensions
2Measurement precision
If a catheter with large outer diameter is used for thermodilution measurements, then continuous indicator fluid infusion is possible, but the measurement variability increases
Solution Approach 1:
By separating the temperature measurement function (guide wire with sensor) from the indicator infusion function (separate infusion device), the system achieves more precise control over indicator delivery. This segmentation allows for consistent infusion rates and better temperature control, reducing measurement variability
Solution Approach 2:
The guide wire with temperature sensor acts as an intermediary between the blood flow and the measurement system, allowing continuous monitoring without requiring a large-bore catheter in the coronary artery itself. The separate infusion device serves as another intermediary, delivering the indicator through the guide catheter without direct contact with the coronary artery
3Loss of information
If absolute blood flow values are measured in individual coronary arteries, then patient-specific diagnostic information is obtained, but the medical significance is limited without reference to normal values
Solution Approach 1:
The system enables continuous measurement of temperature and calculation of blood flow parameters throughout the procedure. This continuous data acquisition allows for both absolute flow values and dynamic assessment of flow changes in response to interventions, providing comprehensive diagnostic information
Solution Approach 2:
The system provides real-time feedback through continuous temperature monitoring and flow calculation. This feedback loop allows operators to adjust infusion rates, assess measurement quality, and evaluate the impact of interventions on coronary blood flow, enhancing the diagnostic value of the absolute measurements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate measurement of absolute coronary blood flow and FFR values, enhancing the medical usefulness of blood flow measurements by providing a basis for comparing patient-specific flows to normal values, thereby aiding in the diagnosis and treatment of coronary diseases.
Implementation Method 1
application of the thermodilution principle with continuous infusion of an indicator fluid
Implementation Method 2
measurement of blood temperature and of the temperature of the mixture of blood and indicator fluid by the temperature sensor
Data Source
AI summary
The invention relates to a method and a system for determining the blood flow in an individual coronary artery of a patient, wherein the method comprises the steps of positioning a temperature sensor mounted at a distal portion of a guide wire at a distal position in the coronary artery, positioning an infusion catheter in the coronary artery such that the distal end of the infusion catheter is proximally of the temperature sensor, measuring the blood temperature with the temperature sensor, infusing cold indicator fluid with a known infusion rate and known or measurable temperature into the coronary artery by the infusion catheter, measuring the temperature of the mixture of blood and indicator fluid by the temperature sensor, and calculating the coronary blood flow by a formula based on the known and measured quantities. In an extended version, the method comprises steps for relating the calculated coronary flow value to related normal flow values, or related FFR values, or a related flow resistance.