Personal electrocardiogram monitor

#This invention relates to equipment for monitoring the electrical activity of the heart in a living body, and particularly to portable electrocardiograph monitors.

#A number of portable devices exist for monitoring the electrical activity of the heart. U.S. Pat. No. 4,351,164 to Allain, Jr. discloses a self-powered life monitor in a pocket-sized, tubular container with electrode probes on one end which are capable of piercing the skin to rest in subcutaneous tissue and an LED light source on the other end to indicate the existence and strength of an electrical potential indicative of bioelectric activity.

#Sarnoff et al., in U.S. Pat. No. 3,792,700, describes a handheld battery-operated cardiac monitor which converts a signal picked up by two spaced electrodes on the body to pulsing light or to an audible beeping signal indicative of the heart beat. The monitor is provided with a flashing lamp and audible monitor and is attached via two electrical leads to two electrodes placed in the user's armpits.

#FIG. 1A is a perspective view of the preferred embodiment of the ECG monitor according to the present invention, particularly illustrating the application of the monitor to a patient's chest.

#FIG. 1B is a magnified, perspective view of the ECG monitor shown in FIG. 1A.

#FIG. 1C illustrates a portion of the signal tracing shown in FIGS. 1A and 1B.

#For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

#With reference to FIG. 1, a personal ECG monitor 10 according to the present invention is shown in operating position in contact with the chest of a patient 12 and is additionally shown in a magnified view illustrating the three electrodes 14, 16, and 18 on the back of the unit. The front side of monitor 10 includes a liquid-crystal display (LCD) 20, adapted to provide an ECG signal tracing 22 with its time axis parallel to the longitudinal axis of the monitor 10. A portion of signal tracing 22 is illustrated at reference numeral 24, which indicates the relative positions and amplitudes of the P, Q, R, S and T waves of a normal ECG signal.

#Electrodes 14, 16, and 18 are dry electrodes mounted directly to the back side of monitor 10 in a longitudinal line. The use of dry electrodes eliminates the discomfort associated with pastes and gels used to make electrical contact between the patient's skin and the electrodes of conventional systems and additionally eliminates the time-consuming task of preparing the paste or gel and the skin. Electrodes of the type used for monitor 10 are preferably silver or silver chloride although conductive plastic and other metals are also suitable, and they exhibit typical impedance on the order of 100 to 1K ohms in the frequency range from 0.1 to 100 Hz. The electrodes further preferably have stability over time and repeated use, and minimal electrode polarization. Dry electrodes for use in ECG monitors are described by Geddes et al in Ann. Biomed. Eng. 1973, 1(3): 356-357.