Pacesetter, Inc.

Other

St. Jude Medical Ab

Ralink Technology Corporation

Louis Wong

Dorin Panescu

Andre B Walker

Euljoon Park

Cem M Shaquer

Gene A Bornzin

Shahrooz Shahparnia

Jiong Xia

Weiqun Yang

Mihir Naware

Shohan T Hossain

Allan Olson

Ajit Pillai

Charles Neder

Lyle Frank Weaver

Chungwen Dennis Lo

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.

Tissue characterization using intracardiac impedances with an implantable lead system

Techniques are provided for controlling therapy provided by the implantable cardiac stimulation device based on cardiogenic impedance. A cardiogenic impedance signal (or intracardiac impedance signal) is an impedance signal representative of the beating of the heart of the patient in which the device is implanted. The cardiogenic impedance signal is sensed along a sensing vector passing through at least a portion of the heart so that the sensed impedance is affected by the mechanical beating of the heart along that sensing vector. Pacing therapy is automatically and adaptively adjusted based on the cardiogenic impedance signal. For example, pacing timing parameters such as the atrioventricular delay and the inter-ventricular delay may be adjusted. Preferably, the adjustments are adaptive, i.e. the adjustments are performed in a closed-loop so as to adapt the adjustments to changes in the cardiogenic impedance signal so as to optimize therapy. In one particular example, the adjustments are performed so as to reduce a degree of fractionation within a cardiogenic impedance waveform.

Closed-loop adaptive adjustment of pacing therapy based on cardiogenic impedance signals detected by an implantable medical device

An implantable device monitors and treats heart failure, pulmonary edema, and hemodynamic conditions and in some cases applies therapy. In one implementation, the implantable device applies a high-frequency multi-phasic pulse waveform over multiple-vectors through tissue. The waveform has a duration less than the charging time constant of electrode-electrolyte interfaces in vivo to reduce intrusiveness while increasing sensitivity and specificity for trending parameters. The waveform can be multiplexed over multiple vectors and the results cross-correlated or subjected to probabilistic analysis or thresholding schemata to stage heart failure or pulmonary edema. In one implementation, a fractionation morphology of a sensed impedance waveform is used to trend intracardiac pressure to stage heart failure and to regulate cardiac resynchronization therapy. The waveform also provides unintrusive electrode integrity checks and 3-D impedancegrams.

Systems and methods to monitor and treat heart failure conditions

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.

Wireless receiving system with an adaptively configurable analog to digital converter

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 electrode-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. The multi-phasic waveform refresh signal may be modulated to contain configuration information, status information, or other information.

Implantable cardiac device with satellite refresh

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.

Method and implantable medical device for measuring an electrical bio-impedance of a patient

A circuit is disclosed that comprises a capacitor gain-boost circuit and an amplifier coupled to capacitor gain-boost circuit. A capacitor gain-boost circuit comprises of capacitor, gain-boost amplifier and biasing circuit. The gain-boost amplifier and capacitor provides optimum biasing operation and performance. Accordingly, through the use of capacitor gain-boost circuit, the supply voltage range and power consumption of an amplifier is optimized while the gain of amplifier is improved.

Capacitor gain-boost circuit

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.

Method and apparatus for measuring battery depletion in implantable medical devices

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.

Methods and devices for reducing integrated circuit power consumption in implantable cardiac stimulation devices

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.

Growing community of inventors

Sunnyvale, CA, United States of America

Louis Wong