Haemodynamic data estimation apparatus and method of use
Inventors
King, David H • Al-Qaisi, Mohammed
Assignees
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Publication Number
US-11678808-B2
Publication Date
2023-06-20
Expiration Date
Abstract
A system and method for deriving information on disease in vascular segments for example mean pressure, drop in mean pressure and/or hydraulic resistance, from such measured waveforms is described. The waveforms can, for example, be measured non-invasively using Doppler ultrasound or magnetic resonance techniques. Form Factors (Vff, Pff) for the velocity waveform and the central arterial pressure are determined. Lesions may be detected and located using the estimated non-invasive hemodynamic information.
Core Innovation
A system is provided that estimates local blood pressure at an interest location in a mammal’s vascular system using non-invasive measurements. The system measures a reference blood pressure at a reference location, where the reference blood pressure includes a systolic pressure and a diastolic pressure. The measurements collectively define the reference blood pressure that is received by a waveform converter and processor.
The system captures a representation of a velocity waveform of blood flow at an interest location using a waveform capture assembly focused on the interest location. The waveform converter and processor analyzes the captured representation and identifies a plurality of parameters associated with the waveform and the reference blood pressure. The processor estimates a local blood pressure at the interest location based on the reference blood pressure and the waveform-derived parameters, and generates an output for user presentation.
The estimation includes calculating a central mean pressure as a sum of two thirds of the diastolic reference blood pressure plus one third of the systolic reference blood pressure. The processor determines a first measure from the parameters identified in the analyzed velocity waveform and determines a second measure based on the difference between the reference systolic blood pressure and the reference diastolic blood pressure divided by the calculated central mean pressure value. The estimated mean blood pressure at the interest location is calculated by dividing the second measure by the first measure for an intermediate value, adding one to the intermediate value for a second intermediate value, and dividing the calculated central mean pressure by the second intermediate value.
The system provides at least one visual indicia for a user based on the estimate of local blood pressure, facilitating disease detection. The interest location is distal from the reference location, and the system provides visual indicia related to estimated mean blood pressure differences associated with lesion detection and lesion localization along a vascular pathway.
Claims Coverage
The document includes one independent claim. Across the dependent claims, the inventive feature set is refined to specify the waveform capture modalities, a particular waveform-to-parameter computation from a single cardiac cycle, spatial relationships between the reference and interest locations, and segment- and threshold-based visual indicia tied to estimated pressure differences and lesion identification.
Reference blood pressure measurement with waveform-based local estimation
Measuring a reference blood pressure of a mammal at a reference location, capturing a representation of a velocity waveform of blood flow at an interest location, and using the reference blood pressure together with analyzed waveform parameters to estimate a local blood pressure at the interest location.
Central mean pressure calculation from systolic and diastolic reference values
Calculating a central mean pressure as a sum of two thirds of the diastolic reference blood pressure plus one third of the systolic reference blood pressure.
Intermediate ratio-based computation yielding mean pressure estimate
Determining a first measure from the plurality of parameters identified in the analyzed blood flow velocity waveform; determining a second measure based on the difference between the reference systolic blood pressure and the reference diastolic blood pressure divided by the calculated central mean blood pressure value; dividing the second measure by the first measure for an intermediate value; adding one to the intermediate value for a second intermediate value; and dividing the calculated central mean blood pressure by the second intermediate value, yielding an estimate of mean blood pressure at the interest location.
User visual indicia for disease detection from estimated local blood pressure
Providing at least one visual indicia for a user based on the estimate of local blood pressure, facilitating disease detection.
Waveform capture assembly selected from Doppler or MRI modalities
Estimating the local blood pressure using a waveform capture assembly selected from continuous wave (CW) Doppler ultrasound, duplex Doppler ultrasound, and magnetic resonance imaging (MRI).
Waveform parameters derived from a single cardiac cycle
Estimating local blood pressure by deriving relative maximum, relative minimum, and relative mean blood velocities from a single cardiac cycle at an interest location and computing a first measure as (maximum minus minimum) divided by the mean velocity.
Distal interest location relative to the reference location
Defining the interest location as distal from the reference location of the reference blood pressure.
Segment-level display of estimated mean blood pressure difference between two locations
Providing a display showing a visual representation of a vascular segment between two selected interest locations along with indicia representing an estimated mean blood pressure difference between those locations.
Threshold-based visual indicators corresponding to significant lesions and their location
Providing visual indicators that correspond to threshold changes in estimated mean blood pressure differences for a segment versus proximal and distal segments, to indicate a significant lesion and its location relative to the subject’s surface anatomy.
Overall, the claims cover a system that measures a reference blood pressure, captures and analyzes a velocity waveform at an interest location, computes a central mean pressure from systolic and diastolic reference values, applies an intermediate ratio-based calculation to estimate mean pressure at the interest location, and provides visual indicia to facilitate disease detection, with refinements for Doppler/MRI capture modes, single-cycle waveform parameter derivation, distal spatial arrangement, and segment/threshold-based lesion-related display indicia.
Stated Advantages
Facilitating disease detection.
Documented Applications
Disease detection using visual indicia based on estimated local blood pressure.
Lesion detection and lesion localization along a vascular pathway based on abrupt changes and/or threshold-based visual indicators tied to estimated mean blood pressure differences.
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