Electricity: electrical systems and devices – Safety and protection of systems and devices – High voltage dissipation
Reexamination Certificate
1996-05-16
2001-01-23
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
High voltage dissipation
C361S115000
Reexamination Certificate
active
06178079
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to annunciator devices for organ stimulating systems implantable in the body of a patient and in particular to such devices which may be used in combination with implantable defibrillator systems, for example, and be assured of attracting the attention of the patient upon the occurrence of a predetermined event.
BACKGROUND OF THE INVENTION
Implantable defibrillation systems are known in the art which deliver a high-voltage defibrillation pulse to the heart when the onset of fibrillation is detected and/or in the event of a detected complete loss of cardiac output. Such known devices are also capable, if the heart exhibits an arrhythmia such as atrial fibrillation, atrial flutter or tachycardia, or ventricular tachycardia, of cardioverting the heart by delivering a low-voltage pulse in an attempt to regain synchronous operation of the heart, instead of delivering the high voltage defibrillation pulse. In known devices of this type, it would be desirable to provide a compact, efficient device to alert the patient that his implanted device needs attention or is about to defibrillate.
It is known from U.S. Pat. No. 4,086,916 to Freeman at al., for example, to contain a cardiac monitoring system in a wristwatch worn by a patient, the system including circuitry for detecting an erratic heartbeat, a missing pulse or other irregularities and providing an alarm indication, audio and visual, when such an event is detected.
An implantable pacing system is disclosed in U.S. Pat. No. 4,102,346 to Fulker which includes an alarm device as part of the implanted unit which generates an alarm signal to inform the pacemaker user when the battery source of power of the pacemaker is nearing end of life or is malfunctioning.
An implantable tissue stimulating device is disclosed in U.S. Pat. No. 4,345,603 to Schulman which activates an alarm which informs the patient in whom the system is implanted that the battery is in need of replacement. After the user has been so informed, the user applies a magnet externally in the vicinity of the implanted unit to deactivate the monitoring system and thereby cease the continued operation of the alarm.
A pacemaker for controlling tachycardia is disclosed in U.S. Pat. No. 4,407,289 to Nappholz et al. also disclosing means for informing a pacemaker user of the remaining battery life. The user places a magnet externally in the vicinity of the implanted unit, which thereby causes the implanted unit to generate two pulses which can be seen on the patient's ECG waveform. The time separation between the two pulses indicates the remaining battery potential. Application of the magnet, after the pulses have been generated, temporarily disables the device.
In U.S. Pat. No. 5,190,034 to Sholder, an implantable arrhythmia treatment system is disclosed which includes reliable protection against the release of unneeded treatment pulses, that is, which provides protection against a false-positive output. The disclosed system utilizes an alarm generator which may be disposed in the implanted unit, or in an external unit. The alarm may be of any type which does not require constant, active monitoring by the user, such as a sensory alarm, for example, an audio alarm generator or a tactile alarm generator or “tickler”.
Other examples of implantable arrhythmia devices which include an alarm generator, either audio, tactile, or visual, are found in U.S. Pat. Nos. 4,295,474 to Fischell; 4,210,149 to Heilman et al.; and 3,783,877 to Bowers.
According to the current state of the art, error conditions are typically announced within an implantable cardioverter defibrillator (ICD) using a piezo annunciator or beeper. The current Eagle Model 2800 in development by Pacesetter, Inc., A St. Jude Medical Company of Sylmar, Calif., for example, utilizes a piezo actuator to flex the titanium can at audio frequencies. However, in some instances, the efficacy of audio emissions from devices implanted abdominally can be questioned. The attenuation of the audio transmitted through tissue is dramatic and aged patients commonly have hearing loss that further decreases their sensitivity to implanted audio generators.
It was in light of the foregoing that the present invention was conceived and has now been reduced to practice.
SUMMARY OF THE INVENTION
According to the invention, an annunciator is provided for an organ stimulating system which is implantable in the body of a patient. In one embodiment, it comprises a hollow canister having a cylindrical internal cavity, first and second electrically conductive coils encircling the canister lying in transverse, preferably perpendicular, planes which intersect along the longitudinal axis of the internal cavity, and a cylindrical permanent magnetic roller having an outer peripheral surface engageable with an inner peripheral surface of the canister and being freely rotatable within the canister. The roller is magnetized at right angles to the roller axis producing a permanent magnetic field and signal generators, either AC or DC, sequentially energize the electrically conductive coils to produce a rotating magnetic field interacting with the permanent magnetic field of the roller and causing the roller to roll about the inner peripheral surface of the canister. The permanent magnetic roller, by its movement, produces vibrations which are imparted to the casing of the organ stimulating system. Specifically, the rolling motion of the roller results in a movement of its center of gravity in a vibration producing orbit. The orbital frequency, &OHgr;, of the center of gravity of the roller is &ohgr;·d/(D−d), where &ohgr;=rate of rotation of said roller, d=diameter of said roller, and D=inner diameter of the cavity of said canister. In another embodiment, the roller may be replaced by a ball and the internal cavity may be spherical or ellipsoidal.
A primary object of the invention, therefore, is to produce an annunciator for an implanted pacemaker which produces vibration, has low power requirements, and requires minimal space.
In another manner of describing the invention, a magnetized ball or cylinder is placed between two or more coils in a cylindrical cavity or other appropriately shaped cavity. When the coils are driven appropriately, either at a fixed frequency, at an externally derived variable frequency, or as triggered pulses dependent on voltages induced in the coils by the motion of the magnet, the magnetized element is caused to roll around inside the cavity and produce vibrations. In the case of the cylindrical magnet additional non magnetic balls can be placed between the ends of the magnet and the ends of the cavity to act as bearings and coincidentally produce additional vibration at a frequency different from that of the magnet. Where the current pulses to the coils are triggered by voltages induced in the coils the unit is acting as a brushless motor. If higher frequency vibrations are desired, ridges can be formed on either the magnet or the cavity. Either pulsed DC or AC may be employed to drive the invention.
The present invention offers numerous advantages. It provides a novel annunciator device applicable to organ stimulating systems which are implantable in a patient's body. More particularly, the invention may be used in combination with implantable defibrillator systems, for example, and be assured of attracting the attention of the patient upon the occurrence of a predetermined event. Still more particularly, the invention may serve to produce a subaudible vibration which would be detectible by a patient who may have experienced hearing loss. The invention assures a compact structure of simplified design fabricated from commonly available materials and requiring expenditure of minimal electrical energy.
Other and further features, advantages, and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and the follow
Jackson Stephen W.
Pacesetter Inc.
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