Method and apparatus for analyzing cardiovascular systems

• US 4,206,764 A
• Filed: 06/05/1978
• Issued: 06/10/1980
• Est. Priority Date: 12/08/1976
• Status: Expired due to Term

• Current Assignee: Lawrence S. Weisman
• Original Assignee: Weisman & Allen
• Inventors: Williams, William J.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US05/912,558
• Time in Patent Office: 736 Days
• Field of Search: 128/2.05 R, 128/2.05 A, 128/2.05 E, 128/2.05 M, 128/2.05 Q, 128/677-683
• US Class Current: 600/490
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers

Abstract

The operation of a patient'"'"'s cardiovascular system is analyzed by positioning an inflatable cuff over an extremity of the patient so that a blood vessel in the extremity experiences the cuff pressure and then modifying the pressure in the cuff through a cycle in which the vessel is occluded. A first electrical signal is generated as a function of the pressure in the cuff during the cycle and a second electrical signal is independently generated as a function of the rate of change of pressure in the cuff through use of a transducer which receives a fluid signal proportional to the pressure in the cuff and moves a core with respect to a wire coil to generate the rate of change signal. The two signals are plotted relative to one another and the resulting plot includes information relating to cardiovascular disfunctions such as arhythmia, ischemia and hypertrophy.

Claims

1. The method of analyzing the functioning of the cardiovascular system in a mammal comprising:

applying an inflatable pressure chamber against the body of the mammal in proximity to a blood vessel so that the pressure within the chamber is exerted against the vessel;

gradually varying the pressure in the chamber between a value at which the vessel is occluded to prevent blood flow therethrough and a pressure value below the diastolic pressure in the vessel over a time period extending over a number of heartbeats;

continuously generating a plot of the instantaneous rate of change of pressure in the chamber as a function of pressure during such pressure change time period;

and detecting anomalies in the plot which are related to anomalies in the functioning of the mammal'"'"'s cardiovascular system.

2. The method of claim 1 in which the time period over which said pressure is varied comprises an interval between ten seconds and one minute.

3. Apparatus for generating a plot of information related to the functioning of the cardiovascular system of a mammal comprising:

an inflatable pressure chamber adapted to be positioned on the body of the mammal in proximity to a blood vessel so that a pressure is exerted on the exterior of the vessel which is a direct function of the pressure within the chamber;

means for modifying the pressure within the chamber through a cycle of varying pressure between a level which causes occlusion of the vessel and a level of pressure below diastolic pressure in the vessel over a time period of at least several heartbeats;

means for generating a first electrical signal proportional to the average pressure within the chamber;

means for continuously generating a second electrical signal proportional to the instantaneous rate of change of pressure within the chamber;

and means for generating a plot of the first electrical signal as a function of the second electrical signal during the cycle.

4. The apparatus of claim 3 in which the means generating said second electrical signal comprises a transducer in communication with the pressure within the chamber.

5. The apparatus of claim 4 wherein said transducer includes a diaphragm and means subjecting said diaphragm to the pressure within the chamber so as to move as a function of the pressure within the chamber, said transducer also includes means for generating a magnetic field and a coil disposed in the field, and means for creating relative movement between the coil and the field as a function of changes in position in said diaphragm.

6. The apparatus of claim 5 wherein said means subjecting said diaphragm to chamber pressure subjects one side of the diaphragm to the pressure within the chamber and further including means subjecting the other side of the diaphragm to the average pressure applied to the chamber.

7. The apparatus for analyzing the functioning of the cardiovascular system in a mammal comprising:

an inflatable cuff adapted to encircle an extremity of the mammal;

means for inflating the cuff including means for varying the pressure in said cuff over a time period;

a transducer having a chamber divided into two sections by a resilient diaphragm;

a fluid conduit connecting one of the diaphragm sections to the interior of the cuff;

fluid conduit means connecting the other of the diaphragm sections to a source of pressure equal to the average pressure applied to the cuff;

and means for continuously generating a signal representative of the instantaneous rate of motion of the diaphragm and means recording said signal over said time period.

8. The apparatus of claim 7 wherein said means for generating a signal which is a function of the rate of motion of the diaphragm generates an electrical signal.

9. The apparatus of claim 8 wherein said means for generating an electrical signal as a function of the rate of motion of the diaphragm includes a magnet and a wire coil and means for moving the magnet relative to the coil as the diaphragm moves so as to continuously generate electrical signals in the coil as a function of the instantaneous rate of motion of the diaphragm.