Preclinical testing and optimization of a novel fetal micropacemaker

Bar‐Cohen, Yaniv; Loeb, Gerald E.; Pruetz, Jay D.; Silka, Michael J.; Guerra, Catalina; Vest, Adriana Nicholson; Zhou, Li; Chmait, Ramen H.

doi:10.1016/j.hrthm.2015.03.022

Cited by 22 publications

(12 citation statements)

References 15 publications

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“…In the first two fetal sheep experiments, the Ir electrode encountered high resistance and was unable to penetrate the myocardium on a total of four attempts [4]. This led us to review our previous acute rabbit experiments[26].…”

Section: 0 Resultsmentioning

confidence: 99%

“…Fetal pacemaker were percutaneously implanted into 7 near-term fetal sheep (gestation age at 112–129 days) according to the procedure described by Bar-Cohen et al [4]. The histology and biocompatibility results can also be found there.…”

Section: 0 Methodsmentioning

confidence: 99%

“…Features from left to right: battery case of lithium cell, which functions as return electrode; glass sleeve for epoxy encapsulation; printed circuit board with discrete surface-mount circuitry and RF coil for inductive recharging; flexible lead (75 µm Pt-30Ir with Parylene-C insulation; epoxy friction disk over welded joint, corkscrew electrode (254 µm Ir with Parylene-C insulation). (This figure is adapted from Bar-Cohen et al [4])…”

Section: Figure1mentioning

confidence: 99%

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Minimally invasive implantable fetal micropacemaker: mechanical testing and technical refinements

Zhou

Vest

Peck

et al. 2016

Med Biol Eng Comput

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This paper discusses the technical and safety requirements for cardiac pacing of a human fetus with heart failure and hydrops fetalis secondary to complete heart block. Engineering strategies to meet specific technical requirements were integrated into a systematic design and implementation consisting of a novel fetal micropacemaker, a percutaneous implantation system, and a sterile package that enables device storage and recharging maintenance in a clinical setting. We further analyzed observed problems on myocardial fixation and pacing lead fatigue previously reported in earlier preclinical trials. This paper describes the technical refinements of the implantable fetal micropacemaker to overcome these challenges. The mechanical performance has been extensively tested to verify the improvement of reliability and safety margins of the implantation system.

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Section: 0 Resultsmentioning

confidence: 99%

Section: 0 Methodsmentioning

confidence: 99%

Section: Figure1mentioning

confidence: 99%

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Minimally invasive implantable fetal micropacemaker: mechanical testing and technical refinements

Zhou

Vest

Peck

et al. 2016

Med Biol Eng Comput

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“…The in vivo study protocol conformed to the Guide for the Care and Use of Laboratory Animals and was approved by the Institutional Animal Care and Use Committees at the University of Southern California and the Los Angeles Biomedical Research Institute. Fetal micropacemakers with rates between 100 bpm and 150 bpm were implanted into seven fetal sheep according to the procedure discussed in Bar-Cohen, et al [19]. Devices were implanted fully charged, but supply voltage, and therefore pacing rate, decreased over time, providing observations of pacing rate at different voltages.…”

Section: Methodsmentioning

confidence: 99%

Design and Testing of a Transcutaneous RF Recharging System for a Fetal Micropacemaker

Vest

Zhou

Huang

et al. 2017

IEEE Trans. Biomed. Circuits Syst.

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We have developed a rechargeable fetal micropacemaker in order to treat severe fetal bradycardia with comorbid hydrops fetalis. The necessarily small form factor of the device, small patient population, and fetal anatomy put unique constraints on the design of the recharging system. To overcome these constraints, a custom high power field generator was built and the recharging process was controlled by utilizing pacing rate as a measure of battery state, a feature of the relaxation oscillator used to generate stimuli. The design and in vitro and in vivo verification of the recharging system is presented here, showing successful generation of recharging current in a fetal lamb model.

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“…After the birth, the infant could then be implanted with a standard pacemaker with epicardial leads. We have developed a fetal micropacemaker to meet this prenatal need (Loeb et al ., 2013) and are currently performing pre-clinical studies in fetal sheep (Bar-Cohen et al ., 2015). This paper describes a novel electrophysiological method that provides useful insights into the quality of the electrode-tissue interface during the course of such chronic experiments.…”

Section: Introductionmentioning

confidence: 99%

A novel method to estimate safety factor of capture by a fetal micropacemaker

et al. 2016

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We have developed a rechargeable fetal micropacemaker in order to treat severe fetal bradycardia with comorbid hydrops fetalis, a life-threatening condition in pre-term non-viable fetuses for which there are no effective treatment options. The small size and minimally invasive form factor of our design limit the volume available for circuitry and a power source. The device employs a fixed-rate and fixed-amplitude relaxation oscillator and a tiny, rechargeable lithium ion power cell. For both research and clinical applications, it is valuable to monitor the electrode-myocardium interface in order to determine that adequate pacemaker output is being provided. This is typically accomplished by observing the minimal stimulus strength that achieves threshold for pacing capture. The output of our simple micropacemaker cannot be programmatically altered to determine this minimal capture threshold, but a safety factor can be inferred by determining the refractory period for ventricular capture at a given stimulus strength. This is done by measuring the minimal timing between naturally occurring QRS complexes and pacing stimuli that successfully generate a premature ventricular contraction. The method was tested in a pilot study in 4 fetal sheep and the data demonstrate that a relative measure of threshold is obtainable. This method provides valuable real-time information about the electrode-tissue interface.

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Preclinical testing and optimization of a novel fetal micropacemaker

Cited by 22 publications

References 15 publications

Minimally invasive implantable fetal micropacemaker: mechanical testing and technical refinements

Minimally invasive implantable fetal micropacemaker: mechanical testing and technical refinements

Design and Testing of a Transcutaneous RF Recharging System for a Fetal Micropacemaker

A novel method to estimate safety factor of capture by a fetal micropacemaker

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