Intrinsic frequency analysis for left ventricle ejection fraction or stroke volume determination

• US 9,480,406 B2
• Filed: 10/17/2014
• Issued: 11/01/2016
• Est. Priority Date: 10/18/2013
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Pahlevan, Niema, Tavallali, Peyman, Rinderknecht, Derek, Gharib, Morteza
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): Morales, Jon Eric C
• Application Number:
  US14/517,702
• Publication Number:
  US 20150112219A1
• Time in Patent Office: 746 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0228 Microwave sensors
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• CPC Class Codes: A61B 5/0013 Medical image data A61B1/00011, A61B6/56, A61B8/56 take precedence
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/1102 Ballistocardiography
• CPC Class Codes: A61B 5/1128 using image analysis A61B5/1127 takes precedence
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 8/065 to determine blood output from the heart in general A61B5/029
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012

Abstract

Hardware and software methodology are described for non-invasively monitoring cardiac health. Hemodynamic waveforms variously acquired for a subject are analyzed to calculate or approximate intrinsic frequencies in two domains in two domains across the Dicrotic Notch. Together with associated notch timing, heart rate and blood pressure values left ventricle ejection fraction and/or stroke volume can be determination.

Claims

1. A system for acquiring and analyzing a hemodynamic waveform of a subject by Intrinsic Frequency (IF) analysis, the system comprising:

a scanner adapted to capture a signal corresponding to a hemodynamic waveform; and

at least one computer processor connected to the scanner by a wired or wireless connection, wherein the computer processor is adapted to receive the signal for the hemodynamic waveform, determine a Dicrotic Notch using the signal, calculate first and second intrinsic frequencies (ω

₁, ω

₂) on each side of the Dicrotic Notch and at least one of other IF parameters including a₁, b₁, a₂, b₂, and c for the waveform, and output a signal corresponding to at least one of left ventricle ejection fraction (LVEF) and stroke volume (SV).

2. The system of claim 1, wherein LVEF is calculated as a function of the IF parameters and p_min, p_max, p_mean, T₀ and HR.

3. The system of claim 1, wherein SV is calculated as a function of the IF parameters and p_min, p_max, p_mean, T₀ and HR.

4. A non-transitory computer readable medium having stored thereon instructions, which when executed cause one or more processors to:

determine a Dicrotic Notch using an input signal corresponding to a hemodynamic waveform;

calculate, by Intrinsic Frequency (IF) analysis, first and second intrinsic frequencies (ω

₁, ω

₂) on each side of the Dicrotic Notch and at least one of other IF parameters including a₁, b₁, a₂, b₂, c for the hemodynamic waveform; and

output a signal corresponding to at least one of left ventricle ejection fraction (LVEF) and stroke volume (SV).

5. The computer readable medium of claim 4, including instructions for LVEF calculation as a function of the IF parameters and p_min, p_max, p_mean, T₀ and HR.

6. The computer readable medium of claim 4, including instructions for SV calculation as a function of the IF parameter and p_min, p_max, p_mean, T₀ and HR.

7. A method of analyzing a signal using a computer comprising a processor, the method comprising:

noninvasively acquiring a signal for a hemodynamic waveform of a subject with a sensor device, wherein the signal is acquired without calibrating the sensor device, and wherein the sensor device outputs signal magnitude by a selection of voltage, light intensity, microwave intensity, displacement or pressure;

analyzing, by the processor, the signal magnitude of each of a first section and a second section of the hemodynamic waveform signal, wherein the waveform includes a Dicrotic Notch, to determine first and second intrinsic frequencies (ω

1, ω

2) on opposite sides of the Dicrotic Notch; and

outputting, by the processor, a result for at least one of left ventricle ejection fraction (LVEF) and stroke volume (SV).

8. The method of claim 7, wherein LFEF is calculated as a function of at least some of Intrinsic Frequency parameter (ω

₁, ω

₂, a₁, b₁, a₂, b₂, c) and p_min, p_max, p_mean, T₀ and HR.

9. The method of claim 7, wherein SV is calculated as a function of at least some of Intrinsic Frequency parameter (ω

₁, ω

₂, a₁, b₁, a₂, b₂, c) and p_min, p_max, p_mean, T₀ and HR.

10. The method of claim 7, wherein the waveform is selected from an arterial pressure wave, a wall displacement wave, a flow wave, or a velocity wave.

11. The method of claim 10, wherein the waveform is obtained from skin motion.