Abstract:
A single use disposable esophageal electrode structure is formed with a planar sheet body member. The body member carries a plurality of spaced-apart conductive electrode members. A layer of adhesive on the body member can be used to affix it to an esophageal probe. A plurality of conducting members is coupled to the body member. Each of the conducting members is in turn coupled to a respective one of the electrodes. A free end of the conducting members carries an electrical connector for connection to other electrical units.

Description:
FIELD OF THE INVENTION 
     The invention pertains to noninvasive cardiac sensing or stimulating. More particularly, the invention pertains to an apparatus and a method for noninvasively pacing a subject&#39;s heart while simultaneously conducting for cardiac analysis. 
     BACKGROUND OF THE INVENTION 
     It has been recognized that esophageal electrodes are particularly useful in connection with noninvasive esophageal pacing. One such electrode is disclosed for example in co-pending and commonly assigned U.S. Pat. Application Ser. No. 930,748, now U.S. Pat. No. 4,817,611, entitled Esophageal Electrocardiography Electrode. 
     It has also been recognized that transesophageal electrocardiography can be used for the purpose of studying myocardial One such system is disclosed in commonly copending U.S. Pat. application Ser. No. 267,459 entitled Method and For Detection of Posterior Ischemia. 
     It has also be recognized that transesophageal echocardiography can be utilized for the purpose of detecting or evaluating among other conditions, myocardial ischemia. It would be desirable to be able to combine the capability of esophageal electrodes and the capability of echocardiography probes into a unit so as to be able to stress the heart and simultaneously study its characteristics. 
     SUMMARY OF THE INVENTION 
     An apparatus and met are provided for esophageal heart pacing or monitoring. An apparatus in accordance with invention has a flexible plastic sheet member. The sheet member, which can be generally of a rectangular shape, carries a plurality of spaced-apart electrode members. 
     A layer of adhesive is carried on the opposite side of the sheet member from the electrodes. Each of the electrodes is connected to one member of a plurality of insulated wires. 
     The insulated wires can be formed on an elongated MYLAR sheet member which is affixed at one end to the sheet member. At the other end of the elongated MYLAR sheet member is an electrical connector which is in turn connected to each of the conductors of the sheet member. 
     The electrical connector can in turn be coupled to a switch for selecting various pairs of electrodes. Outputs from or inputs to the selected pair of electrodes can be coupled to or received from an electrocardiograph or an esophageal pacing unit. 
     Signals from the esophageal pacing unit can be applied to the selected pair of electrodes for the purpose of noninvasively pacing the heart of the subject. Alternately, signals from the selected pair of electrodes can be provided to an amplifier for further processing for the purpose of driving electrocardiograph. 
     A method of esophageal pacing using a probe insertable into the esophagus of the subject includes the steps of affixing a disposable plurality of electrodes to the probe; positioning the probe in the esophagus; selecting at least one of the electrodes for pacing; and applying a selected electrical pacing signal to at least the selected electrode. 
     The present esophageal electrode is especially advantageous in that it can be manufactured as a single use element which can be affixed to a reusable probe prior to use. After use, the electrode unit can be discarded. 
     Alternately, the present multi-electrode structure could be permanently affixed to an esophageal probe. For example, the present electrode structure could be used with an esophageal ultrasonic probe. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings in which the details of the invention are fully and completely disclosed as a part of this specification. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a partial, side, schematic view of a subject illustrating the relationship between a probe in accordance with the present invention and the heart of the subject; 
     FIG. 2 is an enlarged portion of a probe carrying a multi-element electrode in accordance with the present invention; 
     FIG. 3 is an elevational view of one side of a disposable multi-electrode esophageal unit; 
     FIG. 4 is a second view of the disposable multi-electrode esophageal unit of FIG. 3; 
     FIG. 5 is a sectional view taken along plane 5--5 of FIG. 1; and 
     FIG. 6 is a pictorial diagram of an electrode selecting switch in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawing and will be described herein in detail a specific embodiment thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
     FIG. 1 illustrates a subject S having a heart H and an esophagus E with a probe 10 positioned therein. The probe 10 carries a disposable esophageal electrode structure 12. The structure 12 is formed with a flexible medical grade plastic base member 20. The base member 20 carries a plurality of spaced-apart conducting elements 22-32 on a surface 20a. 
     Each of the elements 22-32 is formed of a biocompatible conducting material. Each of the elements 22-32 is permanently affixed to the base member 20. The base member 20 on a surface 20b opposite the surface 20a carries a layer of adhesive 34. The layer of adhesive 34 is used to affix the member 20 to the reusable probe 10. 
     The adhesive layer 34 can be formed of any biocompatible adhesive with adequate strength so as to fix the electrode structure 12 to the probe 10 for the length of any desired procedure. Subsequent to completion of the desired procedure, the electrode structure 12 is removed from the probe 10 and disposed of. The probe 10 can then be sterilized and reused. 
     A plurality of conducting members 36 is attached in a region 38 to the member 20. The plurality 36 can be formed with a plastic base member 39 on which is deposited a plurality of spaced apart conducting traces 36a-36f. Each of the traces, such as the trace 36a is electrically connected to a respective one of the conducting members 22-32, such as the member 22. 
     It will be understood that the details of the formation of the traces 36a-36f and the way in which those traces are carried by the plastic member 39 are not limitations of the present invention. Similarly, the details of how the traces 36a-36f interconnect with the conducting members 22-32 are also not a limitation of the present invention. 
     A second end of the plurality 36 carries an electrical connector 40 of a conventional variety. The connector 40 can be mated with a corresponding connector 42 which is carried by a multiple conductor cable 44. The cable 44 is in turn coupled to a manually operable switch 46. 
     The switch 46 could for example be implemented as a two-pole three position switch. It will be understood that the exact details of the switch 46 are not a limitation of the present invention. The switch 46 is used to manually select a pair of electrodes from the plurality 22-32. Output from the selected pair of electrodes, or input thereto, on a two-conductor cable 48 can be coupled to an ECG or received from an esophageal pacing unit 50. 
     The disposable multi-electrode element 12, in combination with the probe 10, makes it possible to combine cardiac pacing as a form of stress simultaneously with echocardiography to determine and sense heart function. For example, if the probe 10 is a transesophageal ultrasonic probe of a type marketed by Hoffrel Instruments, Inc., Model 482, the electrode structure 12 can be used for pacing the left atrium of the heart H. Simultaneously, an ultrasonic transmitter and receiver 52 on the probe 10 transmits ultrasonic waves toward the heart H and senses ultrasonic reflections therefrom for the purpose of forming an image of the cardiac chambers as the heart H is being simultaneously stimulated. 
     In a typical procedure, the sheet electrode member 12 is affixed to the perimeter of the probe 10 using the layer of adhesive 34. The electrode structure 12 is located at a level about 10 centimeters above the ultrasonic transmitter and receiver 52 in the probe. 
     The ultrasonic transmitter/receiver 52 is carried at a distal end of the probe 10. The multi-electrode element 12 is carried on the probe 10 adjacent the transmitter/receiver 52 but spaced therefrom. 
     The probe 10 is inserted in a conventional fashion into the esophagus E of the subject S. The electrode structure 12 is then connected via connectors 40, 42 to switch selector 46. The appropriate electrodes are selected and then either an esophageal preamplifier or a pacing unit is coupled to the cable 48 for sensing signals from or for pacing the heart H. 
     By way of example and not by wy of limitation, the width of each of the electrode members 22-32 can be on the order of 7 millimeters with a corresponding spacing therebetween. The length dimension of the sheet member 20 can be on the order of 63 millimeters and the width dimension can be on the order of 40 millimeters. 
     The length of the plastic extension member 40, which could be formed of MYLAR can be on the order of 50 centimeters. The body member 20 can also be formed of a MYLAR sheet. It will be understood that any medical grade plastic could be used for the body member 20 without departing from the spirit and scope of the present invention. 
     Further, in a typical installation the switching unit 46 can be connected so as to switch as electrode pairs, electrodes 22, 32; 24, 30; or 24,26. 
     Alternately, the multiple electrode system 12 can be fabricated permanently attached to an imaging probe. Imaging probes, of the type discussed above, usually include an ultrasonic transmitter and receiver located at the end of the probe. 
     The transmitter is located in the esophagus below the heart and is oriented on the probe to transmit toward the heart. Reflected ultrasonic waves are detected by the transceiver, converted to corresponding electrical signals and transmitted from the probe to outside analysis circuitry. 
     Hence, it will be understood that the multiple electrodes 22-32 could be permanently attached to the body of the esophageal ultrasonic probe as generally indicated in FIG. 1. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the novel concept of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.