Towards Low Energy Atrial Defibrillation

Philip Walsh, Vivek Kodoth, David McEneaney, Paola Rodrigues, Jose Velasquez, Niall Waterman, OJ Escalona

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiac impedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50% magnitude) shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50–300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p <0.01) while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA) within the same patient group (|Δ(IAMSAS1-IAMSAS3)[1 Hz − 20 kHz] = 20.82 Ω-Hz (SD(σ) = 10.77 Ω-Hz), p <0.01); both trends being absent in all patients that failed to cardiovert. Efficient transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation.
LanguageEnglish
Pages22378-22400
JournalSensors
Volume15
DOIs
Publication statusPublished - 3 Sep 2015

Fingerprint

Electric Impedance
Shock
shock
impedance
Radio
Transmitters
radio frequencies
Electric Countershock
Defibrillators
transmitters
electric batteries
energy
Switching frequency
Substrates
direct current
Spectrum analysis
Skin
Implantable Defibrillators
spectrum analysis
therapy

Keywords

  • Wireless power
  • battery-free
  • implantable
  • impedance
  • RF defibrillator
  • rectilinear waveform
  • cardioversion
  • atrial fibrillation
  • AF
  • ECG
  • intracardiac impedance spectroscopy.

Cite this

Walsh, P., Kodoth, V., McEneaney, D., Rodrigues, P., Velasquez, J., Waterman, N., & Escalona, OJ. (2015). Towards Low Energy Atrial Defibrillation. Sensors, 15, 22378-22400. https://doi.org/10.3390/s150922378
Walsh, Philip ; Kodoth, Vivek ; McEneaney, David ; Rodrigues, Paola ; Velasquez, Jose ; Waterman, Niall ; Escalona, OJ. / Towards Low Energy Atrial Defibrillation. In: Sensors. 2015 ; Vol. 15. pp. 22378-22400.
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abstract = "A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiac impedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50{\%} magnitude) shock was reliably and repeatedly delivered across the same interface; with >47{\%} DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50–300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p <0.01) while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA) within the same patient group (|Δ(IAMSAS1-IAMSAS3)[1 Hz − 20 kHz] = 20.82 Ω-Hz (SD(σ) = 10.77 Ω-Hz), p <0.01); both trends being absent in all patients that failed to cardiovert. Efficient transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation.",
keywords = "Wireless power, battery-free, implantable, impedance, RF defibrillator, rectilinear waveform, cardioversion, atrial fibrillation, AF, ECG, intracardiac impedance spectroscopy.",
author = "Philip Walsh and Vivek Kodoth and David McEneaney and Paola Rodrigues and Jose Velasquez and Niall Waterman and OJ Escalona",
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Walsh, P, Kodoth, V, McEneaney, D, Rodrigues, P, Velasquez, J, Waterman, N & Escalona, OJ 2015, 'Towards Low Energy Atrial Defibrillation', Sensors, vol. 15, pp. 22378-22400. https://doi.org/10.3390/s150922378

Towards Low Energy Atrial Defibrillation. / Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, OJ.

In: Sensors, Vol. 15, 03.09.2015, p. 22378-22400.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Towards Low Energy Atrial Defibrillation

AU - Walsh, Philip

AU - Kodoth, Vivek

AU - McEneaney, David

AU - Rodrigues, Paola

AU - Velasquez, Jose

AU - Waterman, Niall

AU - Escalona, OJ

PY - 2015/9/3

Y1 - 2015/9/3

N2 - A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiac impedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50% magnitude) shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50–300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p <0.01) while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA) within the same patient group (|Δ(IAMSAS1-IAMSAS3)[1 Hz − 20 kHz] = 20.82 Ω-Hz (SD(σ) = 10.77 Ω-Hz), p <0.01); both trends being absent in all patients that failed to cardiovert. Efficient transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation.

AB - A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiac impedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50% magnitude) shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50–300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p <0.01) while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA) within the same patient group (|Δ(IAMSAS1-IAMSAS3)[1 Hz − 20 kHz] = 20.82 Ω-Hz (SD(σ) = 10.77 Ω-Hz), p <0.01); both trends being absent in all patients that failed to cardiovert. Efficient transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation.

KW - Wireless power

KW - battery-free

KW - implantable

KW - impedance

KW - RF defibrillator

KW - rectilinear waveform

KW - cardioversion

KW - atrial fibrillation

KW - AF

KW - ECG

KW - intracardiac impedance spectroscopy.

UR - http://www.mdpi.com/journal/sensors

U2 - 10.3390/s150922378

DO - 10.3390/s150922378

M3 - Article

VL - 15

SP - 22378

EP - 22400

JO - Sensors

T2 - Sensors

JF - Sensors

SN - 1424-8220

ER -

Walsh P, Kodoth V, McEneaney D, Rodrigues P, Velasquez J, Waterman N et al. Towards Low Energy Atrial Defibrillation. Sensors. 2015 Sep 3;15:22378-22400. https://doi.org/10.3390/s150922378