27 KB166 KB25 KB200020242010Pečlin, PolonaRozman, JanezZdovc, Miroštevilka:1letnik:44str. 25-29ISSN:1580-2949COBISSID:796074URN:URN:NBN:SI:doc-VTWV27ADenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijedogselektrična stimulacijaelektrodeneurologynevrologijapsiChronic stimulation of an autonomous nerve with platinum electrodes| Kronična stimulacija avtonomnega živca s platinastimi elektrodami|A spiral nerve cuff (cuff), including thirty-nine platinum electrodes, arranged in thirteen spiral sets of three electrodes (triplet), was installed on the mid-cervical left vagus nerve (vagus) of a Beagle dog. The relevant position of the particular compartment and the optimal stimulation intensities were identified by delivering stimulating pulses to each triplet. The largest mean change in the components of both the ECG and hemodynamic changes was elicited with a stimulating intensity ic = 2.5 mA applied to triplet 9. Every two weeks the aforementioned compartment was stimulated for 20 min with rectangular, charge-balanced, biphasic, current pulses with the parameters: width 100 s, intensity ic = 2.0 mA, frequency 20 Hz, and a time delay between the biphasic phases of 100 s for the time period of 18 months. It was calculated that to induce neural damage a total injected charge of approximately 172.8 mA s per phase at a charge density of 0.1 A s/mmsup2 was injected. At the end of the trial, the neural and encapsulation tissue subjacent to the central group of triplet 9 and the neural and encapsulation tissue subjacent to the silicone insulation were dissected free and analyzed. The extent of the pathology of the neural tissue caused by the presence of the cuff and/or by the electrochemical reactions and the surface of the stimulating cathode in triplet 9 were investigated using light microscopy. The results showed that the usage of a cuff was associated with a build up of connective tissue around the cuff as well as within the cuff. The results also showed that some tissue injury occurred beneath the stimulating cathode of triplet 9. Finally, the results showed an absence of any anomaly at the flat geometric surface of 2 mmsup2 in stimulating the cathode of the triplet 9 which could be attributable to irreversible electrochemical reationsSpiralna objemka, ki je vsebovala devetintrideset platinastih elektrod, razporejenih v trinajst skupin po tri elektrode (trojček), je bila kirurško vstavljena na osrednji del levega vratnega živca vagusa psa pasme Beagle. Položaj določenega področja živca in optimalna jakost stimulacije sta bila določena z dovajanjem stimulacijskih impulzov na vsakega od trojčkov. Največjo povprečno spremembo komponent elektrokardiograma in hemodinamskih sprememb je izzvala jakost stimulacije ic = 2.5 mA, dovedena na trojček 9. Omenjeni predel je bil v obdobju 18 mesecev vsaka dva tedna stimuliran 20 min s pravokotnimi, nabojsko uravnoteženimi izmeničnimi tokovnimi impulzi z naslednjimi parametri: širina 100 s, jakost ic = 2.0 mA, frekvenca 20 Hz in fazni zamik 100 s. Izračunano je bilo, da je bil za povzročitev poškodbe živca skupni vnesen naboj približno 172.8 mA s. Živčni in ovojnični tkivi ob osrednji skupini elektrod v trojčku in tkivi ob silikonski izolaciji so bili na koncu poskusa izrezani in analizirani. Razsežnosti patologije živčnega tkiva zaradi elektrokemijskih reakcij in prisotnosti objemke ter površina stimulacijske katode trojčka 9 sta bili preiskani s svetlobno mikroskopijo. Rezultati so pokazali, da je uporaba objemke povezana z gradnjo veznega tkiva okoli objemke in v njej. Rezultati so tudi pokazali, da je pod stimulacijsko katodo trojčka 9 nastala poškodba živca. Končno so rezultati pokazali, da na ravni geometrijski površini stimulacijske katode trojčka 9 ni bilo poškodb, ki bi jih lahko pripisali nepovratnim elektrokemijskim reakcijamTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije