ELECTROCARDIOGRAPH LEAD DISTRIBUTION AND CONTACT TESTING APPARATUS

• US 3,757,778 A
• Filed: 01/13/1971
• Issued: 09/11/1973
• Est. Priority Date: 01/13/1971
• Status: Expired due to Term

• Current Assignee: Martin H. Graham
• Original Assignee: Martin H. Graham
• Inventors: Graham, Martin H.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/106,008
• Time in Patent Office: 972 Days
• Field of Search: 128/2.6A,2.6B,2.6E,2.6F,2.6G,2.6R,2.6V,2.1B,2.1R,DIG.4
• US Class Current: 600/508
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/303 Patient cord assembly, e.g. cable harness
• CPC Class Codes: A61B 5/308 for electrocardiography [ECG]
• CPC Class Codes: Y10S 128/902 Biological signal amplifier

Abstract

An electrocardiograph apparatus including a recorder electrically connected by a patient cable to a number of electrical terminals in a distribution head so that each terminal forms a contact point for a series of lead wires each adapted to receive electrical impulses from a selected location of the patient'"'"''"'"'s body. To assist verification of correct interconnection, the distribution head incorporates the configuration of a schematic representation of the body with the position of each distributor terminal corresponding to actual examination locations on the patient. As another verification check, the lead wires may be of varying length corresponding to the distance between the terminals and the patient'"'"''"'"'s contact points. An indicator light in the electrocardiograph circuit is de-energized upon establishing connection with the patient to indicate satisfactory contact. Electronic circuitry is provided for comparing and controlling various voltages and reference ground with the patient to derive standard output signals commonly used in EKG analysis.

Claims

1. In electrocardiograph apparatus, a distributor having a plurality of input terminals for receiving electrical signals generated at selected positions on a patient under examination, a plurality of input leads terminating in electrodes adapted to be placed into contact with the patient and connected to said terminals, buffer amplifier means associated with said leads for accepting a high imput impedance signal from the patient and for converting it to a low output impedance signal, extended cable means for connecting the low output impedance signals from said distrubutor to remote amplifying and recording means, a driven ground circuit including means for sensing induced voltages in the patient and means responsive to said last named means for introducing a compensating voltage to one patient electrode whereby the voltage of the patient is kept zero relative to ground, and further in which said means for sensing induced voltages in the patient consists of a filter circuit selectively sensitive to low frequency signals and insensitive to high frequency signals, a differential output for receiving signals from said filter circuit, a ground sensing means for providing a second input to said differential amplifier.

2. An electrocardiograph apparatus comprising a distributor having a plurality of input terminals for transmitting electrical signal generated at selected positions on a patient under examination, a plurality of input leads terminating in electrodes adapted to be placed into contact with the patient, buffer amplifier means associated with said leads for accepting high input impedance signals from the patient and for converting them to low impedance output signals, extended cable means for connecting the low impedance output signals from said distributor to a remote amplifying and recording means, a summing circuit for adding certain ones of said output signals to derive a common signal, differential amplifier means connected to at least two different ones of said buffer amplifier means and summing circuit to amplify the output thereof, means forming a DC sensing circuit with respect to the DC level of the patient and including a feed-back loop for supplying a DC bias signal to the input of said differential amplifier, said feed-back loop having means to define a first sensitive condition for controlling base line drift including means for applying DC bias to the input of said differential amplifier, said drift control means being operable within approximately + or - one-half volt position, and means for establishing circuit centering in which the total voltage wave form of an incoming signal is sensed and said signal centered within + or - one and one-half volt to define a second sensitive condition and means for selectively controlling the operation of said first and second conditions of said feed-back loop.

3. In an electrocardiograph system of the type employing an electrocardiograph having input terminals, apparatus for interconnecting said electrocardiograph to a patient including distributor means, a plurality of first leads coupled between said electrocardiograph input terminals and said distributor means For transmitting thereto electrical signals from said distributor means, said first leads adapted to permit remote location of said distributor means in the immediate proximity of the patient, diagram means formed on said distributor means for forming an outline representation of a human form showing body, arms and legs thereon, a plurality of terminal locations formed on said representation, and including right and left arm, right and left terminal locations and chest terminal locations, at least said arm and leg terminal locations being positioned on the corresponding leg or arm of said representation, a plurality of second leads terminating in electrodes adapted to be placed in contact with the respective examination point on the patient, and including at least right and left arm, right and left leg, and chest leads and connected to the respective ones of said terminal locations, said second leads adapted to extend from the respective terminal locations on said distributor means to the proper examination point of said patient, circuit means within said distributor for connecting said second plurality leads to said first plurality of leads, said circuit means including a plurality of identical buffer amplifiers respectively connected to each electrode lead for accepting a high input impedance signal from the patient and for converting the signal to a low output impedance, indicator means responsive to proper contact of any of said electrodes with the patient to give a visual signal thereof, said indicator means being disposed adjacent to each related terminal location on said distributor means, said indicator means including a light source and a means responsive to a shift in impedance caused by contact of an electrode to the patient to de-energize said light source upon proper connection being established to the patient.

4. A device as in claim 3 wherein said distributor means has a shape including essentially flat surface on which said representation is formed.

5. A device as in claim 3 wherein said distributor means itself is formed in a doll-like representation of the human form.