Abstract: A lead system for use with an implantable pacemaker/cardioverter/defibrillator. The lead system includes a securable pace/sense electrode positioned between the distal tip of the lead and the tricuspid valve. The distal tip of the lead is positioned at the apex of the right ventricle and may or may not be secured there by a second fixation means such as a screw tip or tines. The securable pace/sense electrode allows the defibrillation electrode to be accurately positioned by the patient's surgeon and maintained in intimate contact with the septum wall of the patient's heart, thereby reducing defibrillation thresholds; it provides a sense signal from the region of the His bundle or AV node, which can be used with other electrodes to distinguish between various arrhythmias; and it provides more physiologic pacing leading to greater cardiac output.

Abstract: An implantable medical apparatus operable in conjunction with an attachable lead, and having a housing containing an electronic component, with a header connected to the housing and defining a cavity. A connector element is positioned within the cavity and is operably connected to the electronic component. A lens is connected to the header, such that the connector element may be viewed through the lens to facilitate confirmation of proper connection of a lead to the connector. The header may be transparent, and the lens either formed as part of the header, or detachable therefrom.

Abstract: A header adapter which is a separately molded part and which is designed to be secured to receiving portions of the header and pulse generator case of an implantable cardiac stimulation device, such as a pacemaker or implantable cardioverter-defibrillator, in order to provide a different lead connector port configuration than that provided by the header of the device. The header adapter has a plurality of adapter lead connector ports and a plurality of lead connectors affixed to a rear portion (mounting side) thereof. The lead connectors extend outwardly from the rear portion of the header adapter, and are insertable into corresponding lead connector ports of the header of the implantable cardiac stimulation device to which the header adapter is to be secured.

Abstract: The present invention is directed toward providing a composite lead body design for pacing and defibrillation leads. This lead body design improves the lead crush resistance in the lead segment that is implanted in the patient's clavicular region, while maintaining good fatigue resistance in the lead segment implanted in the heart. The clavicular segment has a generally flat profile. By flattening the clavicular segment proximal to the venous entry site, the lead will have a lower profile. Also, by substantially co-aligning the conductors within the clavicular segment, the crush resistance of the lead is significantly improved.

Abstract: An implantable cardiac therapy device collects patient ECG and device status information, including cardiac event interval information, why therapy was or was not applied, and patient response to therapy, in connection with an arrhythmic episode and correlates such information in a data frame that may be stored for later telemetric transmission to an external instrument or that may be transmitted in real time to the external instrument. The data frame is decoded and parsed by the external instrument for presentation to an attending physician in a time correlated format.

Abstract: A lead sealing device that resides within the connector cavity of a pacemaker or defibrillator intended to prevent fluid intrusion by automatically sealing the lead lumen when the lead connector is inserted. The sealing mechanism may be in the form of a silicone disk located at the base of the space defined by the connector cavity in which the lead is inserted to make electrical and physical contact. It may be fixedly located at the bottom of the connector cavity, or may be a movable plug located within the connector cavity at a location other than the bottom of the cavity, such as adjacent to the connector block. In that case, the pin will make contact with the movable plug immediately after passing through the connector block, and will remain in contact with and seal the lead lumen while the pin and plug are further advanced to bring the pin into its final location to make electrical contact with the connector contact.

Abstract: A defibrillation insulating device prevents current from directly shunting through the blood pool from the right ventricular defibrillation electrode to a superior vena cava electrode and vice versa. This forces current to flow through the heart muscle, thus increasing the current density throughout the heart, to depolarize the majority of the cardiac tissue with a minimum of energy.

Abstract: An improved electrolytic capacitor is provided by producing an anode foil which has areas which are not subject to stress during manufacturing being highly etched and those areas which are subject to stress during manufacturing being lightly etched or not etched at all. The process of the invention provides an etch mask to cover during the etch process those portions of the anode foil which will be subjected to stress during construction of the capacitor. The highly etched areas, which are very brittle, provide increased capacitance and thus improved energy density. For layered or stacked capacitors, a weld tab is covered with the etch mask to allow connection of the anode layers. Additionally, strong edges may be maintained thereby reducing the possibility of cracking that would normally occur during the stamping and assembly operations.

Abstract: A method for the automated manufacture of defibrillation lead electrodes is disclosed. A metallic defibrillation electrode coil is first embedded in silicone rubber. The location of the coil is mapped using a machine vision system and then a CO.sub.2 laser is used to ablate the silicone overlying the coil to expose a controlled portion of the coil while leaving the remainder securely embedded in the silicone. The power density of the laser is below that which would affect the surface or bulk properties of the coil.

Abstract: An implantable cardiac stimulator having a housing defining an interior cavity and having an exterior surface, and a defibrillation pulse generator circuit contained within the cavity. The housing exterior surface has a number of ridges, and each ridge includes at least two surfaces that are angularly offset from each other at an edge. The ridges may be formed by creating grooves in the housing in a closely spaced arrangement.

Abstract: Intracardiac lead for compliant fixation of a distal end of the lead to cardiac tissue. A fixation helix is disposed at the distal end of the lead. The fixation helix has a first end rigidly attached to the compliant fixation device and a second end that is sharpened to facilitate insertion of the fixation helix into cardiac tissue. The fixation helix can be designed to provide for either electrically active or inactive fixation. Once the lead is implanted in the cardiac tissue, the compliant fixation device, connecting the lead with the fixation helix, reduces the amount of lead movement that is transferred to the patient's tissue at the site of implantation of the fixation helix and reduces those forces from lead movement that could cause dislodgment of the fixation helix.

Abstract: A method and apparatus for inducing fibrillation in a patient's heart by delivering a direct current stimulus to the heart from a DC-to-DC converter. The hardware of a conventional implantable cardioverter/defibrillator (ICD) is utilized with a modification to the control algorithms. Particularly, when it is desired to induce fibrillation in a patient's heart, typically during ICD implant defibrillation threshold (DFT) testing, a command is delivered from an external instrument to the ICD to deliver the fibrillation shock. The DC-to-DC converter which is normally used to charge the ICD high voltage capacitors is activated and immediately thereafter or following a short period to allow the high voltage capacitors to charge, the high voltage output switches of the output stage are closed. This delivers the output current from the DC-to-DC converter to the defibrillation electrodes and through the patient's heart. This stimulus is continued for a predetermined time of between about 30 milliseconds to 5 seconds.

Abstract: A system is provided to control operation of an implantable medical device based upon detected EMI (electromagnetic interference). A correlator produces a correlation function indicating the level of an EMI component of an input biomedical signal that includes a biomedical signal component and an EMI component, and that is monitored relative to a predetermined threshold to allow the device to operate in a normal manner as long as the intensity or level of the EMI component is such that it does not affect or interfere with device operation. One or more remedial measures may be selected in the event the level of the EMI component exceeds a predetermined threshold. The system is useful with any electronic device which receives an electronic information signal which may include an EMI component.

Abstract: A method of discriminating among cardiac rhythms of supraventricular and ventricular origin by exploiting the differences in their underlying dynamics reflected in the morphology of the waveform. A phase space representation of the dynamics of a waveform is obtained from the electrogram signal amplitude by using the technique of delay embedding. A first cardiac rhythm electrogram of known origin is sensed and a phase space representation or trajectory is generated for use as a template. A second or test cardiac rhythm electrogram is sensed and a phase space representation is generated from the detected waveform complex. This second phase space representation is compared to the template to distinguish between the origins of the first and second cardiac rhythms. If a test trajectory is sufficiently different from the template trajectory, the test complex is deemed to have different dynamics, and therefore be from a different origin than the template.

Abstract: An implantable device, such as a defibrillator, has a conforming housing that is adapted to follow to the contours of the patient's body at a device implantation site, while complying with pressures applied to the patient's body and with body flexion. In one form of the invention, the device housing is articulated at one or more hinge locations to provide a segmented housing that conforms to an implantation site through movement about the hinge axis. Another embodiment of the invention provides a flexible housing that surrounds a flex-circuit assembly.

Abstract: An implantable medical apparatus operable in conjunction with an attachable lead, and having a housing containing an electronic component, with a header connected to the housing and defining a cavity. A connector element is positioned within the cavity and is operably connected to the electronic component. A lens is connected to the header, such that the connector element may be viewed through the lens to facilitate confirmation of proper connection of a lead to the connector. The header may be transparent, and the lens either formed as part of the header, or detachable therefrom.

Abstract: A pulse generator having a housing for enclosing and containing pulse generator defibrillation circuitry, particularly adapted to allow for ease of manufacture and use, is disclosed. At least one surface of the housing is electrically conductive and connected to the pulse generator circuitry for delivering defibrillating energy to the heart. The defibrillator is provided with a case activating lead connector cavity having two connector blocks. By plugging in a lead with a pin long enough to contact the only first connector block, the lead becomes active. Using a plug with a longer pin to contact both blocks activates the can. To use neither a lead in the case activating port, nor an active can, a plug with a short or nonconductive pin may be used to plug the cavity without activating the can. By using this system, various electrode configurations can be used as required to provide the optimum system for a given patient.

Abstract: A fail-safe clock generator which has particular utility in implantable cardiac defibrillators includes a crystal oscillator for generating a crystal clock signal, a back-up circuit, and a one-shot generator. The back-up circuit includes a low frequency oscillator for generating a low frequency clock signal having a frequency less than that of the crystal clock signal, and an overspeed/underspeed detector responsive to the low frequency clock signal for detecting the frequency of the crystal clock signal during each period of the low frequency clock signal, and for generating a back-up mode control signal in response to detection of either an overspeed or underspeed failure mode over a plurality of consecutive periods of the low frequency clock signal.

Abstract: A method and apparatus for inducing fibrillation in a patient's heart by delivering an alternating current stimulus to the heart from a DC-to DC converter. The hardware of a conventional implantable cardioverter/defibrillator (ICD) is utilized with a modification to the control algorithms. Particularly, when it is desired to induce fibrillation in a patient's heart, typically during ICD implant defibrillation threshold (DFT) testing, a command is delivered from an external instrument to the ICD to deliver the fibrillation shock. The DC-to-DC converter which is normally used to charge the ICD high voltage capacitors is activated and immediately thereafter a first pair the high voltage output switches of the output stage are closed for about 4 milliseconds. This delivers an initial pulse of one polarity. Following an interval of about 4 milliseconds, a second pair of the high voltage output switches are closed for 4 milliseconds delivering an opposite polarity pulse.

Abstract: A suture sleeve having an elongated body defining a bore and having a relief aperture at a first intermediate position on the body and communicating with the bore. The sleeve includes a pair of actuator tabs connected to a second intermediate position on the body and extending therefrom, and at least a portion of the relief aperture is positioned between the tabs such that actuation of the tabs causes enlargement of the aperture. The sleeve may be movable between a tighter state in which a lead passing through the bore does not readily slide longitudinally within the bore, and a looser state, in which the lead may slide readily through the bore.