An implantable device and method for providing anti-arrhythmia therapy to, and including arrhythmia in, a patient's inadequately functioning heart are disclosed A pacemaker, defibrillator and microprocessor are utilized in conjuction with an electrode lead system adapted to be connected to the heart for providing the therapy and for inducing arrhythmia Circuitry is employed in the pacemaker and defibrillator to generate respective trains of spaced pulses for delivery to corresponding portions of the electrode lead system, and a smoothing filter is provided in series with the trains of pulses to smooth each of the trains of pulses into discrete single pulse having a continuous waveform The spacing, durations and polarities of the pulses in the trains are selectively variable so that the waveforms of the discrete single pulses can be selectively varied to provide diferent waveforms therein, in accordance with the needs of the patient and the programming of the device

Apparatus and method for generation of varying waveforms in arrhythmia control system

Ingestible electronics have revolutionized the standard of care for a variety of health conditions. Extending the capacity and safety of these devices, and reducing the costs of powering them, could enable broad deployment of prolonged monitoring systems for patients. Although prior biocompatible power harvesting systems for in vivo use have demonstrated short minute-long bursts of power from the stomach, not much is known about the capacity to power electronics in the longer term and throughout the gastrointestinal tract. Here, we report the design and operation of an energy-harvesting galvanic cell for continuous in vivo temperature sensing and wireless communication. The device delivered an average power of 0.23 μW per mm2 of electrode area for an average of 6.1 days of temperature measurements in the gastrointestinal tract of pigs. This power-harvesting cell has the capacity to provide power for prolonged periods of time to the next generation of ingestible electronic devices located in the gastrointestinal tract.

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Prolonged energy harvesting for ingestible devices.

The truncated decaying exponential waveshape has become the de facto standard for implantable cardiac defibrillators. However, the optimal defibrillation waveshape with respect to delivered energy remains unknown. To this end, this study has derived the theoretically optimal waveshapes for monophasic and biphasic defibrillation shocks as predicted from a lumped-component model of cardiac tissue in conjunction with the "charge-banking" and "charge-burping" hypotheses of defibrillation. These derivations predict that a truncated ascending exponential waveshape-with a shock time constant, /spl tau//sub s/, always equal to the underlying tissue time constant, /spl tau//sub m/-minimizes the delivered energy required for defibrillation. These predictions are quantitatively consistent with available experimental data. Thus, to the extent that "charge-banking" and "charge-burping" are assumed to be valid and accurate models of defibrillation, these derivations identify the theoretical "gold standards" of defibrillation waveshapes requiring minimum delivered energy.

Theoretical predictions of the optimal monophasic and biphasic defibrillation waveshapes

Prolonged energy harvesting for ingestible devices

A non-invasive electrical stimulator for pacing the heart. The stimulator generates a ramped current waveform which reduces muscle stimulation and pain associated with external stimulation of the heart.

Ramped waveform non-invasive pacemaker

This paper describes a waveform which is more efficient than the standard square pulse for use in chronic cardiac pacing. The experimental techniques are discussed and long term results obtained from animals implanted with endocardial catheters are presented.

A more efficient waveform for cardiac stimulation.

A simple linear pulse-to-pulse cardiac tachometer.

The paper describes improvements made in biogalvanic energy sources, which significantly prolong their life and reliability. The results of long-termin vivo implants are presented, and comparisons are made between the original bare-metal biogalvanic sources and those which utilise a variety of semipermeable anodic membranes.

R. W. Wehnert

Papers

A more efficient waveform for cardiac stimulation.

A simple linear pulse-to-pulse cardiac tachometer.

Improvements in biogalvanic energy sources