Methods and systems for distal recording of phonocardiographic signals

• US 7,137,955 B2
• Filed: 04/18/2003
• Issued: 11/21/2006
• Est. Priority Date: 04/19/2002
• Status: Expired due to Fees

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Inventors: Canady, Larry D. Jr., Honeyager, Kevin S., Bartels, Keith A.
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US10/418,207
• Publication Number:
  US 20030220577A1
• Time in Patent Office: 1,313 Days
• Field of Search: 600485-499, 600/513, 600/528, 600/586
• US Class Current: 600/528
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/6817 Ear canal
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 7/023 for introduction into the body, e.g. into the oesophagus oesophageal ECG probes A61B5/285
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

Methods and systems for determining cardiovascular parameters of a patient. In an exemplary embodiment, the method includes placing a phonocardiogram sensor on a patient'"'"'s body at a first distal location to the heart, and a blood-pressure waveform sensor at a second distal location to the heart. Then, a first set and a second set of waveforms is obtained from the phonocardiogram sensor and the blood-pressure waveform sensor, respectively. A signal processing or conditioning operation may optionally be performed using the first and second sets of waveforms. Then, a time delay between a dicrotic notch signal and an S2 signal is determined. A blood pressure pulse transit time value is calculated by adding S2D, representing a time delay between a patient'"'"'s heart valve closure time and an arrival time of the S2 signal at the first distal location, to the time delay between a dicrotic notch signal and an S2 signal. Cardiovascular parameters are then determined using the determined blood pressure pulse transit time and at least one physical parameter representative of a arterial distance between a location of the aortic valve and a location of the blood-pressure waveform sensor.

Claims

1. A method to determine a S2D value representing a time delay between a patient'"'"'s heart valve closure and an arrival of a patient'"'"'s S2 heart sound at a distal location to the heart, the method comprising:

placing a first phonocardiogram sensor on a patient'"'"'s chest;

placing a second phonocardiogram sensor at the distal location to the heart;

obtaining a first set of phonocardiogram signals from the first phonocardiogram sensor;

obtaining a second set of phonocardiogram signals from the second phonocardiogram sensor;

performing a signal processing or conditioning operation using the first and second sets of phonocardiogram signals; and

determining the time delay based on results obtained from the signal processing or conditioning operation.

2. The method according to claim 1, wherein performing a signal processing or conditioning operation comprises determining a patient'"'"'s individual heart cycles.

3. The method according to claim 2, wherein determining a patient'"'"'s individual heart cycles comprises determining a delimiter in the patient'"'"'s individual heart cycles.

4. The method according to claim 3, wherein determining a delimiter of heart cycles comprises determining an R-wave using a first set of electrocardiogram signals obtained from at least one electrocardiogram sensor positioned on the patient'"'"'s body.

5. The method according to claim 3, wherein determining a delimiter of heart cycles comprises determining an S2 signal, representative of a second heart sound associated with closure of the heart valves, from the first set of phonocardiogram signals.

6. The method according to claim 5, wherein performing a signal processing or conditioning operation includes using dicrotic notch of arterial blood pressure waveform as a trigger.

7. The method according to claim 1, wherein the distal location is a patient'"'"'s elbow.

8. The method according to claim 1, wherein placing the second phonocardiogram sensor at the distal location comprises placing the second phonocardiogram sensor on a bone or a tissue at the distal location.

9. The method according to claim 1, wherein performing a signal processing or conditioning operation comprises one or more of performing an ensemble averaging operation, using a bandpass filter, and determining a stable detection point on a distal S2 signal.

10. A method for determining cardiovascular parameters of a patient, the method comprising:

placing a phonocardiogram sensor on a patient'"'"'s body at a first distal location to the heart;

placing a blood-pressure waveform sensor at a second distal location to the heart;

obtaining a first set of waveforms from the phonocardiogram sensor;

obtaining a second set of waveforms from the blood-pressure waveform sensor;

performing a signal processing or conditioning operation using the first and second sets of waveforms;

determining a time delay between a dicrotic notch signal detected from the second set of waveforms and an S2 signal detected from the first set of waveforms;

determining a blood pressure pulse transit time value by adding S2D, representing a time delay between a patient'"'"'s heart valve closure time and an arrival time of the S2 signal at the first distal location, to the time delay between a dicrotic notch signal and the S2 signal; and

determining cardiovascular parameters of a patient using the determined blood pressure pulse transit time and at least one physical parameter representative of a arterial distance between a location of aortic valve of the heart and a location of the blood-pressure waveform sensor.

11. The method according to claim 10, wherein cardiovascular parameters include blood pressure-wave velocity, a patient'"'"'s heart isovolumetric contraction period or the like.

12. The method according to claim 10, wherein performing a signal processing or conditioning operation comprises one or more of performing an ensemble averaging operation, performing a processing using a bandpass filter, and performing a processing to determine a stable detection point on a distal S2 signal.

13. A method for determining a corrected blood pressure pulse transit time value for a patient, the method comprising:

placing a phonocardiogram sensor on a patient'"'"'s body at a first distal location to the heart;

placing a blood-pressure waveform sensor at a distal location on the patient'"'"'s body;

obtaining a first set of waveforms from the phonocardiogram sensor;

obtaining a second set of waveforms from the blood-pressure waveform sensor;

performing a signal processing or conditioning operation using the first and second sets of waveforms; and

determining a time delay between a dicrotic notch signal detected from the second set of waveforms and an S2 signal detected from the first set of waveforms;

determining a corrected blood pressure pulse transit time value by adding S2D, representing a time delay between a patient'"'"'s heart valve closure time and an arrival time of the S2 signal at the first distal location, to the time delay between a dicrotic notch signal and an S2 signal.

14. The method according to claim 13 wherein performing a signal processing or conditioning operation comprises one or more of performing an ensemble averaging operation, performing a processing using a bandpass filter, and performing a processing to determine a stable detection point on a distal S2 signal.

15. A system for determining cardiovascular parameters of a patient, the system comprising:

a signal acquisition and processing device;

a blood pressure waveform measuring device coupled to the signal acquisition and processing device; and

at least one phonocardiogram (PCG) sensor coupled to the signal acquisition and processing device, wherein the signal acquisition and processing device obtains a first set of waveforms from the phonocardiogram sensor, obtains a second set of waveforms from the blood-pressure waveform sensor, performs a signal processing or conditioning operation using the first and second sets of waveforms, determines a time delay between a dicrotic notch signal detected from the second set of waveforms and an S2 signal detected from the first set of waveforms, and determines a corrected blood pressure pulse transit time value by adding S2D, representing a time delay between a patient'"'"'s heart valve closure time and an arrival time of the S2 signal at the first distal location, to the time delay between a dicrotic notch signal and an S2 signal.

16. The system according to claim 15, wherein the signal acquisition and processing device includes a display device.

17. The system according to claim 15, wherein the blood pressure waveform measuring device includes a blood pressure cuff device.

18. The system according to claim 15, wherein the blood pressure waveform measuring device includes an arterial tonometer.