GB2337119A

GB2337119A - Measurement of myocardial motion and electrical signals

Info

Publication number: GB2337119A
Application number: GB9809376A
Authority: GB
Inventors: Michael Parnham Travis
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-05-05
Filing date: 1998-05-05
Publication date: 1999-11-10
Also published as: GB9809376D0

Abstract

A transducer (4) for measuring movements of the myocardium and the electrical signals generated by those movements comprises a multi-element strain gauge (9) combined with electrodes, and is retained on the myocardium by suction, thus avoiding intrusion into the myocardium and consequent trauma. Strain gauges (9) for measuring axial and radial strain are attached to each of three legs (2) and vacuum lines (1) and conductors (13) extend down the legs to orifices and electrodes respectively on the bottom of rubber feet (3).

Description

Jill, Key to Illustrations The numbered components illustrated in the

figures are identified as follows:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 vacuum line transducer element medical rubber foot annular transducer cell vacuum orifice strain gauge bridge wiring millivolt sig gnal cable strain gauge terminal pad strain gauges (axial motion) strain gauges (axial and radial motion) strain gauge field relief slots anti- fatigue holes contact electrical conductor electrode terminal pad ( 1\ 1 MEASUREMENT SYSTEM FOR MYOCARDIAL MOTION AND ELECTRICAL SIGNALS 2337119 This invention relates to a measurement system which monitors the motions of the myocardium and its electrical signals.

Measurement of the dynamics of the myocardium and of electrical signals thereby produced provides important information to cardiac surgeons. Currently the dynamics can be measured by sonomicrometry or through instruments inserted into the myocardiurri, but the former lacks the advantages achieved by direct physical contact and the trauma occasioned by the insertion of the latter can endanger the patient. Present measurement of the electrical signals by electrocardiogram cannot be localised to distinct areas of the myocardium.

According to the present invention there is provided a multi-element strain-gauged transducer to measure the axial and radial motions with electrode conductors to measure the corresponding electrical signals of the myocardium, on which it is retained by a vacuum, removing the need for intrusive penetrators such as tines or barbs.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 shows isornetrically a typical example of the invention as a three-element annular transducer, the feet of medical rubber, strain gauges for axial motion and contact electrical conductors all being iHustrated,- Figure 2A iHustrates the same embodiment of the invention from above with the strain gauges for radial motion added., Figure 2B shows the lateral elevation of figure 2A; Figure 3 repeats figure 2A but adds, by detail A, an illustration of the strain field relief slots and anti-fatigue holes;

Figure 4 adds to figure 1 the vacuum fines for the retention system, the signal cable by which data are transmitted, the strain gauge terminal pad, strain gauges to monitor axial motion and the electrode terminal pad; Figure 5 shows from above (A) and laterally (B) the vacuum fine by which the whole unit is retained on the myocardium; and Figure 6 illustrates detail from the side (A) and fi-orn below (B) the vacuum orifice and contact electrode within the medical rubber foot. of the typical example used throughout.

As illustrated, the invention takes the form of an annular transducer 4. During surgery, the transducer is placed by the surgeon against that part of the myocardium which is to be monitored and it is retained there by the medical rubber feet J3) when a vacuum is applied to the orifice 5 through the vacuum line 1. By the same application to the myocardium, the contact electrode conductor 13 is placed in position.

2 WhUst the unit is thus fim-dy and reliably held in place, natural movements of the myocardium induce axially- and radially-oriented movement into the transducer elements 2, which in turn flex and stress the strain gauge bridge, producing an electrical output signal - directly proportional in amplitude and phase to the myocardial motion - which is transmitted alone the signal cable 7. The direct electrical signal generated by those same natural movements of the myocardium is simultaneously fed through the contact electrode conductor 1-31 located on the foot of each transducer element.

Because each transducer element 2 is individually strain-gauged, separate and summed output signals may be measured and compared.

The mechanically-generated electrical signal can then be compared with the electrical signal detected by direct myocardium contact and the evaluation of both wfil assist in diagnosing the heart's condition.

1.3

Claims

A multi-element strain-gauged transducer to measure the axial and radial motions with c 1-P electrode conductors to measure the corresponding electrical signals of the myocardium, on 1 which it is retained by a vacuum, removing the need for intrusive penetrations.
2 A multi-element strain-gauged transducer as claimed in Claim 1, wherein the elements of 0 the transducer are in the form of two or more legs.
3 A multi-element strain-gauged transducer as claimed in Claim 1, in which each transducer element is individually strain-gauged to supply separate information.
4 A multi-element strain-gauged transducer as claimed in Claim 2, whereof the transducer 0 legs are fitted with medical rubber feet at the point of contact with the myocardium.
A multi-element strain-gauged transducer as claimed in Claim 1, wherein retention is effected b means of a vacuum applied through vacuum fines to orifices set in the medical rubber y feet of each transducer element.
6 A multi-element strain-gauged transducer as claimed in Claim 1, whereby separate and summed data obtained through strain gauge techniques may be compared with data obtained 0 directly from contact electrodes, together providing cardiac surgeons with diagnostic information previously not available.