Abstract: A self-cooling transcutaneous energy transfer system is provided for transmitting power to an implantable medical device, such as a defibrillator. The system includes a housing that is supported above the human body by a base so as to define a space between the housing and the body. A primary induction coil is disposed within the housing for transferring electromagnetic energy to the implantable medical device. A cooling fan is attached to the housing for providing forced convective heat transfer from the body. Various power and control circuitry are provided. The system can transfer away heat generated by eddy currents induced in the implantable device by the magnetic flux produced by the induction coil.

Abstract: A sub-assembly module for surface mounting on an implantable medical device hybrid module is provided. The sub-assembly module includes one or more electronic components mounted on a substrate. Interconnection between the electronic components and the hybrid module is established by bond pads on the upper and lower surfaces of the substrate and thru-substrate conducting plugs connecting respective upper and lower bond pads. The electronic components are encapsulated in a layer of insulating material. The electronic components may be chip-and-wire mounted to the sub-assembly module and the sub-assembly module may, in turn, be surface mounted to the hybrid module, permitting the integration of chip-and-wire and surface mount processing for a given hybrid module.

Abstract: A memory device particularly useful in size-constrained electronic products, such as cardiac stimulators. To provide additional memory for such size-constrained products, memory chips are stacked one on top of another. The memory chips are configured to facilitate bonding without crossed contacts, using aligned bonding pads, vias, or castellations. Each memory chip also includes an address selection circuit that receives signals from one or more address lines to selectively enable and disable the memory chips in the stack.

Abstract: An implantable medical device for electrically stimulating the heart to beat generally includes a processor, a plurality of electrodes, a sense amplifier, a pulse generator, and a heart status monitor. The processor can determine when the patient has entered an environment of high electromagnetic interference. When this occurs, the processor forces the implantable device into a safe noise mode. While in the same noise mode (which preferably continues while the patient is experiencing the electromagnetic interference), the implantable device paces the heart on demand and inhibits pacing during the vulnerable period. The processor determines when the vulnerable period is occurring and when the heart needs to be paced by monitoring a status signal from the heart status monitor.

Abstract: A technique for acquiring and accessing information from a medical implantable device. Analog waveforms of interest are sensed and processed by signal acquisition circuitry. Analog parameters of interest are applied to selector switches which are controlled by a logic circuit. The logic circuit is also coupled to an A/D converter for converting the analog signals to digital values. The digital values are stored in dedicated registers and are available for telemetry to an external device upon receipt of a request or prompt signal. When a digitized value is accessed and telemetered, the control logic circuit changes the conductive state of the selector switches to apply the corresponding analog signal to the A/D converter. The resulting digital value is applied to the corresponding register to refresh the accessed and telemetered value. The technique permits the external device to request and configure the implanted device to send only digitized values of interest.

Abstract: A printed circuit board substrate includes cavities in which electronic components, such as integrated circuits, are mounted and encapsulated. Once the electronic components are encapsulated, other electronic components can be mounted above the encapsulated component on the top surface of the substrate, thereby increasing the number of components that can be mounted to a circuit board of a given area. The encapsulated components are mounted using any one of a variety of techniques. The substrate may include multiple conductive layers for electrically interconnecting the encapsulated components to other components.

Abstract: A cardiac lead is provided that is capable of deforming in situ to accommodate difficult myocardial structures. The lead includes a connector for coupling to a cardiac stimulator and a flexible tubular sleeve coupled to the connector. The sleeve is composed of a thermally-sensitive shape-memory polymeric material and is deformable in situ into a permanent shape. An electrode is coupled to the sleeve and a conductor wire is coupled to the connector and to the first electrode.

Abstract: A defibrillator is designed for implantation in a patient and for programming certain of its parameters after implantation, including energy content of a shock waveform and timing of delivery of the shock waveform. A shock waveform generator of the device is responsive to a trigger signal for timed production of a shock waveform having a programmable shape and energy content designed for terminating atrial or ventricular fibrillation (AF or VF) of the patient. A detection circuit processes a sensed cardiac signal of the patient to determine the relative timing of various portions of the cardiac signal, including the P-wave and the T-wave.

Abstract: An implantable cardiac defibrillator is provided. The implantable cardiac defibrillator includes a can, a storage cell for powering the defibrillator, and a circuit module disposed in the can for controlling the defibrillator. The circuit module has a first substrate, a first die coupled to the first substrate, a second die, and a second substrate coupled to and disposed between the first die and the second die. The second substrate has a first plurality of conductors to carry electrical signals to and from the first die and a second plurality of conductors to carry electrical signals to and from the second die. The die may be any of a number of types of electronic components, such as power transistors, memory chips, or others. The stacking of the die saves board space, allowing for further miniaturization or incorporation of additional electronic components.

Abstract: Various endocardial lead assemblies are disclosed that may be particularly useful for placement within the coronary sinus. The lead assemblies may have open ends or closed ends. Lead assemblies having closed ends may be implanted using conventional implantation procedures. Lead assemblies have open ends may be implanted by first locating a stylet within the patient's body and, then, inserting the lead into the patient's body along the stylet. Each disclosed lead assembly uses one or more stents which expand to contact the inner surface of a body vessel once the lead has been properly positioned. Thus, the stents fix the lead at the desired location. Additionally, the stents may be used as electrodes for pacing and/or sensing.

Abstract: An implantable medical device for electrically stimulating the heart to beat generally includes a processor, a plurality of electrodes, a sense amplifier, a pair of comparators, inner and outer target logic units, and pulse generator. The processor controls the magnitudes of inner and outer target reference signals which are generated by the inner and outer target logic units, respectively. The outer target is adjusted to be approximately equal to the peak amplitude of the cardiac signal. The processor stores representations of the outer target reference in memory. Alternatively or additionally, the processor computes a histogram of the relative or absolute number of cardiac cycles that occur over a given period of time for each outer target setting. The processor can be directed to retrieve the outer target representations and/or the histogram from memory and transmit that information to an external programmer for use by a physician.

Abstract: An electromagnetic accelerometer includes a rigid shell with a cavity in which two magnets are fixed at either and of the rigid shell and one magnet is allowed to move between the fixed magnets. The three magnets are arranged so that the movable magnet is suspended between the fixed magnets by magnetic forces from the fixed magnets. A coil of wire surrounds the shell and magnets. An acceleration of the accelerometer causes a displacement of the movable magnet with the cavity. As a result, an electrical current is induced in the coil of wire. The voltage in the coil of wire is proportional to the acceleration experienced by the accelerometer. The electromagnetic accelerometer is particular useful in an implantable pacemaker or defibrillator and can be included in either or both a lead or the housing of the pacemaker. Further, the accelerometer generates its own voltage in response to acceleration and the resulting electrical energy can be used as a power source.

Abstract: An apparatus and method are disclosed by which a laser beam is used to remove or ablate the insulating coating from a desired segment of an insulated conductor without damaging or causing mechanical stress to the wire, so that the wire can be used to transmit electrical signals to an electrode in a implantable medical device. The invention can be applied to one or more conductors that are coiled coaxially and can be used to expose separate portions of two or more conductors if the insulating coatings thereon are differentiated in a way that causes the separate insulating coatings to respond differently to contact with a laser beam.

Abstract: A method is disclosed for rapidly removing electrically insulative coating material from a portion of the titanium housing of an implantable cardiac pulse generator. Pulsed excimer laser radiation ablates an organic coating, such as parylene or a similar polymer, to micromachine a conductive window having sharply defined boundaries or edges. An implantable cardiac pulse generator having an electrically conductive window produced according to the method is also disclosed. The method is suitable for high volume automated production of face or edge window pulse generators, and is also applicable for removal of biomolecular films from other medical articles.

Abstract: A cardiac lead is provided that includes a connector for connecting to a cardiac stimulator and a flexible sleeve coupled to the connector. The sleeve has a first segment, a second segment and a jacket coupling the first segment and the second segment. The jacket is composed of a shape-memory polymeric material which deforms diametrically in situ to selectively disconnect the first segment from the second segment. An electrode is coupled to the sleeve and a conductor is disposed in the sleeve and coupled to the connector and the electrode for conveying electrical signals. The breakaway function of the jacket allows removal of all but a small portion of the lead without dissection of fibrous tissue.

Abstract: A method of implanting small diameter conductive leads for an artificial cardiac pacemaker or other body-implantable medical device includes inserting the lead to be implanted into a predetermined path within the patient's body with the assistance of a stylet for guiding the lead along the path. At least a portion of the stylet which is to traverse the path has an enhanced radiopaque characteristic attributable to the application or addition to the material of which the stylet is composed, of a substance having such radiopaque characteristic. When viewed under fluoroscopy external to the patient's body as the lead is maneuvered along the path, although the thin lead itself may be difficult to see, the stylet is readily discernible by virtue of its enhanced radiopacity, thereby enabling the physician to position the lead at a desired location within the patient's body. For various reasons, the thin lead itself may not be amenable to similar enhancement, which makes the stylet a suitable solution.

Abstract: A lead assembly adapted for endocardial fixation to a human heart is provided. The lead assembly includes a lead body that has a proximal end provided with a connector for electrical connection to a cardiac stimulator. The cardiac stimulator may be a pacemaker, a cardioverter/defibrillator, or a sensing instrument. The distal end of the lead body is connected to a tubular electrode housing. The lead body consists of a noncoiled conductor cable surrounded by a coextensive insulating sleeve. In contrast to conventional leads, the lead body of the present invention does not require coiled conductor wires or an internal lumen. Manipulation of the lead body is via an external guide tube. Lead body diameters of 0.25 mm or smaller are possible.

Abstract: The present invention provides devices and methods for using such devices which can be positioned over cardiac stimulator lead sections which are known to be flawed or which are at risk of failure, such as wire stiffener fractures and electrical shorts. The devices and methods of the invention can protect a patient with an implanted cardiac stimulator whose flawed lead represents a threat to his health or life. The devices and methods of use of the invention provide movable sleeves which can be positioned at various points along the length of a lead at the discretion of the heart surgeon.

Abstract: An implantable medical device electrically stimulates the heart to beat and senses electrical activity in the heart. The medical device generally includes a processor, a plurality of electrodes, and a sense amplifier. The medical device is capable of performing a variety of diagnostic tests, such as a sensing test in which a suitable sensitivity setting is computed for the sense amplifier. An external programmer is also provided to initiate the diagnostic tests. The programmer transmits a start signal to the implantable medical device and the medical device's processor initiates the diagnostic test specified by the programmer via the start signal. The implantable device is capable of completing the diagnostic test without further communication from the programmer or may initiate communication with the programmer during a refractory period in which signals from the programmer will not interfere with the diagnostic test. In the latter case, the programmer responds before the refractory period ends.

Abstract: A training unit generally includes a processor, a magnetic field sensor, a plurality of control switches, and a message and data output device. Placing a PEIS magnet, constructed in accordance with the ISOWD 14994 standard, adjacent to or in contact with the training unit activates the magnetic field sensor, a condition detectable by the processor. Activation of the switches determines which of three modes the training unit will operate. In an instructional mode, the process provides instructional messages to the operator via the message and data output device, which preferably includes a display and an audio speaker. In a coached mode, the training unit informs the operator when to place the magnet adjacent to or in contact with the training unit and when to remove the magnet in accordance with the timing intervals of the PEIS entry code. In a practice mode, the operator initiates and completes the entry code using a PEIS magnet without coaching.