Name
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 intracardiacimpedance (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 (SD(sigma) = 1.62 ), 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 (|(IAMSA(S1)-IAMSA(S3))[1 Hz - 20 kHz] = 20.82 -Hz (SD(sigma) = 10.77 -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. |
Year | DOI | Venue |
|---|---|---|
2015 | 10.3390/s150922378 | SENSORS |
Keywords | Field | DocType |
wireless,battery-free,implantable,impedance,RF,defibrillator | Biomedical engineering,Direct current,Defibrillation,Waveform,Electronic engineering,Radio frequency,Electrical impedance,Maximum power transfer theorem,Cardioversion,Engineering,Amplitude | Journal |
Volume | Issue | ISSN |
15 | 9.0 | 1424-8220 |
Citations | PageRank | References |
0 | 0.34 | 1 |
Authors | ||
7 | ||
Name | Order | Citations | PageRank |
|---|---|---|---|
| p r walsh | 1 | 2 | 1.67 |
| vivek n kodoth | 2 | 2 | 1.67 |
| david mceneaney | 3 | 1 | 3.67 |
| p a rodrigues | 4 | 0 | 0.68 |
| j j velasquez | 5 | 0 | 0.34 |
| n waterman | 6 | 0 | 0.34 |
| o j escalona | 7 | 0 | 0.34 |