Abstract: An implantable system acquires intracardiac impedance with an implantable lead system. In one implementation, the system generates frequency-rich, low energy, multi-phasic waveforms that provide a net-zero charge and a net-zero voltage. When applied to bodily tissues, current pulses or voltage pulses having the multi-phasic waveform provide increased specificity and sensitivity in probing tissue. The effects of the applied pulses are sensed as a corresponding waveform. The waveforms of the applied and sensed pulses can be integrated to obtain corresponding area values that represent the current and voltage across a spectrum of frequencies. These areas can be compared to obtain a reliable impedance value for the tissue. Frequency response, phase delay, and response to modulated pulse width can also be measured to determine a relative capacitance of the tissue, indicative of infarcted tissue, blood to tissue ratio, degree of edema, and other physiological parameters.

Abstract: An implantable system acquires intracardiac impedance with an implantable lead system. In one implementation, the system generates frequency-rich, low energy, multi-phasic waveforms that provide a net-zero charge and a net-zero voltage. When applied to bodily tissues, current pulses or voltage pulses having the multi-phasic waveform provide increased specificity and sensitivity in probing tissue. The effects of the applied pulses are sensed as a corresponding waveform. The waveforms of the applied and sensed pulses can be integrated to obtain corresponding area values that represent the current and voltage across a spectrum of frequencies. These areas can be compared to obtain a reliable impedance value for the tissue. Frequency response, phase delay, and response to modulated pulse width can also be measured to determine a relative capacitance of the tissue, indicative of infarcted tissue, blood to tissue ratio, degree of edema, and other physiological parameters.

Abstract: An implantable system acquires intracardiac impedance with an implantable lead system. In one implementation, the system generates frequency-rich, low energy, multi-phasic waveforms that provide a net-zero charge and a net-zero voltage. When applied to bodily tissues, current pulses or voltage pulses having the multi-phasic waveform provide increased specificity and sensitivity in probing tissue. The effects of the applied pulses are sensed as a corresponding waveform. The waveforms of the applied and sensed pulses can be integrated to obtain corresponding area values that represent the current and voltage across a spectrum of frequencies. These areas can be compared to obtain a reliable impedance value for the tissue. Frequency response, phase delay, and response to modulated pulse width can also be measured to determine a relative capacitance of the tissue, indicative of infarcted tissue, blood to tissue ratio, degree of edema, and other physiological parameters.

Abstract: In a method and device for measuring an electrical bio-impedance of a patient at least one impedance measurement signal is generated by a current pulse generator, the signal having at least one asymmetric multiphasic impedance measurement waveform that is asymmetric in term of pulse amplitude and/or pulse width relative to the operating voltage of the current pulse generator. The waveform has a DC component that is substantially equal to zero, and is adapted to the available voltage headroom of an implantable device that contains the current pulse generator. The impedance measurement signal with the aforementioned waveform is applied to a patient and a resulting impedance signal is produced thereby, from which at least one impedance value is determined.

Abstract: In one embodiment an implantable cardiac device is provided that includes an implantable cardiac stimulation device with an implantable satellite device coupled to it. The implantable satellite device has a charge storage device. The implantable stimulation device having a refresh generator configured to generate a charge and voltage balanced multi-phasic refresh signal with a duration less than a capacitive time constant of an electro-electrolyte interface of the implantable cardiac device and transmit the charge and voltage balanced multi-phasic refresh signal to the implantable satellite device for charging the charge storage device. In various embodiments, the charge and voltage balanced multi-phasic refresh signal having alternating phase signs and null durations between the alternating phases. In some embodiments, the refresh generator is configured to modulate the multi-phasic waveform refresh signal.

Abstract: A circuit is disclosed that comprises a controller and an analog to digital converter (ADC) coupled to controller. The speed and/or the resolution of the ADC is configurable to provide optimum performance during the operation of the ADC. In an embodiment a wireless receiver with an adaptively configurable ADC for is provided. The speed and resolution the ADC is configurable depending on the operational mode of the receiver. Accordingly, through the use of an adaptively configurable ADC, power consumption and speed is optimized for each operational mode.

Abstract: In a method and device for measuring an electrical bio-impedance of a patient at least one impedance measurement signal is generated by a current pulse generator, the signal having at least one asymmetric multiphasic impedance measurement waveform that is asymmetric in term of pulse amplitude and/or pulse width relative to the operating voltage of the current pulse generator. The waveform has a DC component that is substantially equal to zero, and is adapted to the available voltage headroom of an implantable device that contains the current pulse generator. The impedance measurement signal with the aforementioned waveform is applied to a patient and a resulting impedance signal is produced thereby, from which at least one impedance value is determined.

Abstract: Method of product evaluation comprising the steps of applying at least one substance to a surface of an artificial substrate to form a substance-coated surface, wherein the substrate surface demonstrates at least one physical property selected from the group consisting of a total surface energy of from about 15 mJ/m2 to about 50 mJ/m2, a polar component of the total surface energy of from about 0 mJ/m2 to about 15 mJ/m2, a zeta-potential at a pH of about 5.0 of from about ?30 mV to about 30 mV, and combinations thereof, and performing at least one analysis of the substance-coated surface.

Abstract: A method and apparatus for measuring battery depletion in an implantable medical device is presented. The apparatus includes first and second switch pairs disposed in series between the battery and a load, and connected in a parallel arrangement with respect to one another. A capacitor is connected in a first polarity between the battery and the load when only first and fourth switches are closed and in a second polarity when only second and third switches are closed. A comparator circuit causes the switches to reverse the capacitor's polarity based on a comparison of the voltage drop across the capacitor to a threshold value. A counter counts the number of times the capacitor reverses polarity, which is proportional to the amount of charge transferred from the battery during its lifetime in the device and indicative of the battery's level of depletion.

Abstract: A voltage step-down circuit reduces the amount of power drawn from the battery of an implantable cardiac stimulation device (ICD) to supply an integrated circuit (IC) within the ICD. The ICD battery supply voltage is reduced to a level that maintains proper operation of the IC. The reduced battery supply voltage is also regulated such that the IC is supplied with a constant voltage source. The IC consumes less power when supplied by the reduced battery supply voltage than when supplied directly by the battery supply voltage. The present invention promotes ICD battery longevity and reduces the need for frequent ICD battery replacements.

Abstract: Pacing pulse power efficiency is increased in an implantable cardiac stimulation device. The invention includes a cardiac function sensor for sensing cardiac functions. A controller is coupled to the sensor for determining a required cardiac pacing pulse voltage level. A determining means is coupled to the controller for determining a desired battery voltage multiplication factor as a function of the required pacing pulse voltage level. A setting means is coupled to the determining means for setting a battery voltage multiplier to multiply the battery voltage to a level as close as possible to the required pacing pulse voltage level.

Abstract: An active feedback loop is provided in a switched-capacitor circuit to automatically cancel both junction and sub-Vth channel leakage. Low power consumption that is crucial for implantable medical devices is achieved. The circuit technique largely minimizes the effective leakage current when the switch is turned off. This circuit technique of the invention can be used in many different circuit applications.