METHOD AND APPARATUS FOR THE DETECTION AND RECORDATION OF HIGH FREQUENCY SOUND IN THE CARDIOVASCULAR SYSTEM

• US 3,762,397 A
• Filed: 04/19/1971
• Issued: 10/02/1973
• Est. Priority Date: 04/19/1971
• Status: Expired due to Term

• Current Assignee: John M. Cage
• Original Assignee: John M. Cage
• Inventors: Cage, John M.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/135,350
• Time in Patent Office: 897 Days
• Field of Search: 128/2.5R,2.5S,2.6R,21B,2K
• US Class Current: 600/513
• 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

Abstract

High frequency sound, such as that produced by turbulence, in the cardiovascular system is sensed, amplified, demodulated, and filtered to produce an average of the amplitude of the sound, the demodulated signal being synchronously averaged over a plurality of successive cycles of the heart to produce a clear signature trace of the demodulated sound, even in the presence of background noise.

Claims

1. The method of analyzing cardiovascular sound comprising the steps of:

detecting the sound signals produced repetitively from a source within the body;

detecting a periodic condition in the body synchronous with said repetitively produced sound signals;

demodulating said detected sound signals to produce a data signal representative of the average of the amplitude over a selected past period of time;

synchronizing the detected sound signals with said periodic condition in the body synchronous with said detected sound signals;

averaging a plurality of said demodulated signals over a plurality of successive time periods to obtain an average of the amplitudes of the demodulated signals; and

displaying said average of the amplitudes.

2. The method as claimed in claim 1 wherein the step of synchronizing the detected sound signals with a periodic condition comprises the steps of synchronizing with an electrocardiographic signal.

3. The method as claimed in claim 1 wherein the step of detecting the sound signals comprises selecting a band pass above 200 Hz and below 20,000 Hz.

4. The method as claimed in claim 1 wherein the step of averaging a plurality of sound signals comprises averaging over at least 26 signals.

5. Apparatus for analyzing cardiovascular sound comprising:

means for detecting the sound signals produced repetitively from a source within the body;

said periodic condition in the body synchronous with said detected sound signals;

means for demodulating said detected sound signals to produce a data signal representative of the average of the amplitude over a selected past period of time;

Means for synchronizing said detected sound signals with said periodic condition in the body synchronous with said detected sound signals;

means for averaging a plurality of said demodulated signals over a plurality of successive time periods to obtain an average of the amplitudes of the demodulated signals; and

means for displaying said average of the amplitudes.

6. Apparatus as claimed in claim 5 wherein said means for averaging comprises a time averaging computer.

7. Apparatus as claimed in claim 5 wherein said synchronizing means comprises means responsive to the electrocardiographic signal of said body.

8. Apparatus as claimed in claim 5 wherein said means for detecTing said sound signals comprises a microphone positioned near said body.

9. Apparatus as claimed in claim 5 including means for filtering said detected sound signals to pass signals in selected bands above 200 Hz and below 20,000 Hz.