Monopolar Electrode Research Articles

Characterization of Irreversible Electroporation Ablation with a Validated Perfused Organ Model

PurposeTo develop and validate a perfused organ model for characterizing ablations for irreversible electroporation (IRE)–based therapies. Materials and MethodsEight excised porcine livers were mechanically perfused with a modified phosphate-buffered saline solution to maintain viability during IRE ablation. IRE pulses were delivered using 2 monopolar electrodes over a range of parameters, including voltage (1,875–3,000 V), pulse length (70–100 µsec), number of pulses (50–600), electrode exposure (1.0–2.0 cm), and electrode spacing (1.5–2.0 cm). Organs were dissected, and treatment zones were stained with triphenyl tetrazolium chloride to demonstrate viability and highlight the area of ablation. Results were compared with 17 in vivo ablations performed in canine livers and 35 previously published ablations performed in porcine livers. ResultsAblation dimensions in the perfused model correlated well with corresponding in vivo ablations (R2 = 0.9098) with a 95% confidence interval of < 2.2 mm. Additionally, the validated perfused model showed that the IRE ablation zone grew logarithmically with increasing pulse numbers, showing small difference in ablation size over 200–600 pulses (3.2 mm ± 3.8 width and 5.2 mm ± 3.9 height). ConclusionsThe perfused organ model provides an alternative to animal trials for investigation of IRE treatments. It may have an important role in the future development of new devices, algorithms, and techniques for this therapy.

Temperature distribution during radiofrequency ablation of spinal metastases in a human cadaver model: Comparison of three electrodes.

Radiofrequency ablation (RFA) temperatures reaching 45°C in adjacent tissues are cytotoxic to the spinal cord, nerves and surrounding tissues. This study compares different RFA electrodes with regard to the temperature distribution during ablation of spinal metastases. In vitro experimental study in isolated lumbar vertebrae of a human cadaveric spine. The temperature distribution of RFA electrodes was measured during ablation in human cadaveric lumbar vertebrae containing a simulated vertebral body lesion. The analysis compared a novel bipolar RFA electrode with two conventional monopolar RFA electrodes. A vertebral metastasis model was prepared in eight lumbar vertebrae for each electrode. Differences between the electrodes were evaluated with a one-way ANOVA. The lowest temperature at the thermocouples adjacent to the simulated lesion was achieved when using the bipolar RFA electrode (46.4 ± 3.3°C), but temperature difference to the monopolar RFA electrodes was not significant. In the neural foramen and epidural space of lumbar vertebrae the maximal temperature measured when using the bipolar RFA electrode was 37.0 ± 0°C and 37.3 ± 0.7°C, which was significantly lower than during ablation via either of the monopolar RFA electrodes (p ≤ 0.001). Temperatures in areas of adjacent tissue during RFA using a specific for spinal ablation designed electrode with integrated thermocouples were significantly lower compared to other electrodes, potentially reducing temperature related risks during ablation.

Effect of electrolytic lesions of the dorsal diencephalic conduction system on the distribution of Fos-like immunoreactivity induced by rewarding electrical stimulation

The dorsal diencephalic conduction system (DDC) is an important pathway of the brain reward circuitry, linking together forebrain and midbrain structures. The present work was aimed at describing the effect of a DDC lesion on the distribution of Fos-like immunoreactivity (FLIR) following intracranial self-stimulation (ICSS) of the lateral hypothalamus (LH). Rats were implanted with monopolar electrodes and divided into three groups; the first two groups were trained to self-stimulate at the LH, whereas the third group received no stimulation and served as a control. Among the two groups that were trained for ICSS, one of them received a lesion at the DDC and was tested for ICSS on the subsequent 5days. On the last day of testing, control rats were placed in operant chambers without receiving any stimulation, and the remaining rats were allowed to receive the stimulation for 1h. All rats were then processed for FLIR. As previously shown, a lesion at the DDC resulted in significant attenuations of the rewarding effectiveness of LH stimulation. Results also show a higher FLIR in several reward-related areas following LH stimulation, especially in the hemisphere ipsilateral to the stimulation electrode. Compared to non-lesioned rats, lesioned animals had lower FLIR in certain brain regions, suggesting that those regions that were activated by the rewarding stimulation may be functionally interconnected with the DDC.

9. IOM of peripheral nerves, plexus, roots and spinal cord

In the laboratory, motor conduction studies are recorded using surface electrodes. Supramaximal stimulation can synchronously depolarize all the functioning motor axons with minimal temporal dispersion. A well-placed surface electrode captures a large, compound muscle action potential (CMAP). Needle electromyography (EMG) can effectively record only a restricted field of a few cubic millimeters. Near field recording makes possible motor unit analysis and acquisition of pathologic Surface electrodes (including short “EEG” needles) often fail to record intraoperative neurotonics. Intraoperative navigation about nerves depends on reliable neurotonic surveillance and acquisition of amply summated CMAPs after stimulation. Robust conduction studies (and neurotonic recording) can usually be performed if a sufficient length of bare wire (a partially denuded monopolar EMG electrodes) can be implanted intramuscularly. Peripheral motor axons will depolarize if struck with sufficient energy. For a given mass, end velocity 2 of the nerve impact determines (1) whether individual axons will fire and (2) how many axons will fire (i.e., the amplitude of the recorded submaximal nerve action potential). Acutely (or chronically) injured nerves may lose the ability to accommodate; that is, they keep firing repetitively well after the stimulus. Train neurotonics (“A trains” per Romstock, 2000) are likely explained by the “breakdown” of accommodation.

Monopolar hook electrode assisted laparoscopic resection of descending colon cancer

Colorectal cancer accounts for about 25% of all malignant tumors in China. Efficacy and safety of laparoscopic assisted descending colon cancer radical resection have been recognized, and that complete mesocolic excision (CME) plays an important role. For this surgery, most surgeons choose scalpel as the primary instrument, and monopolar hook electrode minimal. A 72-year-old female patient with an adenocarcinoma of the left colon, with pre-operative clinical stage CT3N1M0, was chosen for the study. We use the monopolar hook electrode to finish the laparoscopic assisted descending colon cancer radical resection. The tumor with the surrounding tissue and 4/15 lymph nodes was resected by laparoscopy and colon side to side anastomosis performed. The procedure lasted about 120 minutes with minimal bleeding. Postoperative tumor biopsy revealed a tumor staging of T3N2M0 (IIIB). The patient recovered well following the procedure and was discharged after 4 days. The use of monopolar hook electrode in laparoscopy assisted descending colon cancer radical removal is safe, feasible and effective. The procedure is accurate, safe, provides ease of operating in a narrow space and is relatively inexpensive.

Monopolar hook electrode assisted laparoscopic resection of descending colon cancer

Colorectal cancer accounts for about 25% of all malignant tumors in China. Efficacy and safety of laparoscopic assisted descending colon cancer radical resection have been recognized, and that complete mesocolic excision (CME) plays an important role. For this surgery, most surgeons choose scalpel as the primary instrument, and monopolar hook electrode minimal. A 72-year-old female patient with an adenocarcinoma of the left colon, with pre-operative clinical stage CT3N1M0, was chosen for the study. We use the monopolar hook electrode to finish the laparoscopic assisted descending colon cancer radical resection. The tumor with the surrounding tissue and 4/15 lymph nodes was resected by laparoscopy and colon side to side anastomosis performed. The procedure lasted about 120 minutes with minimal bleeding. Postoperative tumor biopsy revealed a tumor staging of T3N2M0 (IIIB). The patient recovered well following the procedure and was discharged after 4 days. The use of monopolar hook electrode in laparoscopy assisted descending colon cancer radical removal is safe, feasible and effective. The procedure is accurate, safe, provides ease of operating in a narrow space and is relatively inexpensive.

Monopolar hook electrode assisted laparoscopic resection of descending colon cancer

: Colorectal cancer accounts for about 25% of all malignant tumors in China. Efficacy and safety of laparoscopic assisted descending colon cancer radical resection have been recognized, and that complete mesocolic excision (CME) plays an important role. For this surgery, most surgeons choose scalpel as the primary instrument, and monopolar hook electrode minimal. A 72-year-old female patient with an adenocarcinoma of the left colon, with pre-operative clinical stage CT3N1M0, was chosen for the study. We use the monopolar hook electrode to finish the laparoscopic assisted descending colon cancer radical resection. The tumor with the surrounding tissue and 4/15 lymph nodes was resected by laparoscopy and colon side to side anastomosis performed. The procedure lasted about 120 minutes with minimal bleeding. Postoperative tumor biopsy revealed a tumor staging of T3N2M0 (IIIB). The patient recovered well following the procedure and was discharged after 4 days. The use of monopolar hook electrode in laparoscopy assisted descending colon cancer radical removal is safe, feasible and effective. The procedure is accurate, safe, provides ease of operating in a narrow space and is relatively inexpensive.

Energy Dissipation in Ex Vivo Porcine Liver During Electrosurgery.

This paper explores energy dissipation in ex vivo liver tissue during radiofrequency current excitation with application in electrosurgery. Tissue surface temperature for monopolar electrode configuration is measured using infrared thermometry. The experimental results are fitted to a finite-element model for transient heat transfer taking into account energy storage and conduction in order to extract information about "apparent" specific heat, which encompasses storage and phase change. The average apparent specific heat determined for low temperatures is in agreement with published data. However, at temperatures approaching the boiling point of water, apparent specific heat increases by a factor of five, indicating that vaporization plays an important role in the energy dissipation through latent heat loss.

Method of destruction of the pathological excitation sources in the heart by original monopolar electrode

Method of destruction of the pathological excitation sources in the heart by original monopolar electrode

12 V-Class Bipolar Lithium-Ion Battery Using Li4Ti5O12 Anode for Low Voltage System Applications

Lithium-ion batteries using Li4Ti5O12 (LTO) anode realizes high power, long life, and safety for automotive and stationary power applications because the LTO electrode has the advantages of nano-size particle, no lithium plating at quick-charging and low temperature conditions, outstanding safety on internal short-circuit, and thermal stability under high-temperature conditions[1,2]. Recently, LTO-based lithium-ion batteries have been investigated for low-voltage systems such as Start & Stop vehicle systems and the replacement of Pb-acid battery for stationary power supply because the LTO-based batteries have good voltage harmonization with the Pb-acid battery. We have been developing five series-connected LTO-based cells for 12 V low-voltage systems. LiMn1-xFexPO4 (LMFP) is a 4 V-class cathode with high thermal stability compared to such as LiCoO2, LiNi1/3Co1/3Mn1/3O2, and LiMn2O4. Lithium-ion cell with a combination of the LMFP cathode and the LTO anode shows a voltage plateau of 2.5 V for Mn3+/Mn2+ redox. We have been preliminarily studying a thin hybrid electrolyte based on a cubic garnet-type Li7La3Zr2O12(LLZ) as lithium-ion conducting ceramics for 12 V-class bipolar LTO/LMFP battery with liquid-free and separator-free [3]. The bipolar battery has advantages of size reduction and low-cost. In addition, LMFP and LTO can share the same aluminum current collector, which makes the bipolar structure simple. In this study, we report the electrochemical characteristics, the performance of LTO/LMFP cells, and the development of 12 V-class bipolar LTO/LMFP battery using the LLZ-based hybrid electrolyte. LiMn0.85Fe0.15PO4 and LiMn0.85Fe0.1Mg0.05PO4 as the LMFP cathode were hydrothermally synthesized to obtain a small particle size of about 80 nm and no impurity phase. The discharge capacity of cathode increased from 140 to 160 mAh/g by using the LiMn0.85Fe0.1Mg0.05PO4 cathode. We fabricated 1 Ah and 25 Ah-class LTO/LMFP cells in order to investigate the cell performance. Discharge rate capability of the LTO/LMFP cell was improved to be comparable with that of the LTO/LMO cell. High-temperature cycle test exhibited that the LTO/LMFP cell was significantly superior to that of the LTO/LMO cell. The dissolution amount of Mn from the LMFP cathode at 55°C was two order of magnitude smaller than that from the LMO cathode. Fig.1 shows close-circuit voltage (CCV) at 0.2 C rate and open-circuit voltage (OCV) of the five series LTO/LMFP cells and 12 V Pb-acid battery during charge-discharge cycle. Five series LTO/LMFP cells exhibited good voltage harmonization with the 12 V Pb-acid battery in the voltage range between 10 V and 14 V and a smaller polarization compared with the Pb-acid battery. The LTO/LMPF cells are expected to be a replacement of Pb-acid battery in automotive and stationary power storage applications. Therefore, we fabricated the bipolar batteries constructed from five LTO/LMFP cells stacked together, which contained four bipolar electrodes and two monopolar electrodes as endplates for output voltage of 12 V. Cathodes and anodes in bipolar batteries are disposed in contact respectively with opposite sides of a common current collecting element forming a unitary bipolar structure. LTO and LMFP were coated with the LLZ hybrid electrolyte containing 4wt% polyacrylonitrile (PAN) gel polymer [3]. Fig.2 shows the cross section SEM image of LTO/LLZ/LMFP and typical charge-discharge curve of the bipolar battery. A few micrometers thickness of LLZ hybrid electrolyte layer was thin enough to reduce the internal resistance. This LLZ substrate did not only work for the lithium-ion conductor but also retain sufficient strength and electronic insulation even for a little amount of the PAN gel polymer and separator-free in the hybrid electrolyte layer. The bipolar battery exhibited the voltage plateau of 12.5 V, which is matched with the voltage of Pb-acid battery. Fig.3 shows discharge rate performance of the bipolar battery at various discharge rates. The discharge capacity retention at 5 and 20 C rates was 94 and 75%, respectively. The polarization of the bipolar battery was relatively small even at a high discharge rate. It was demonstrated that the bipolar battery had good performance in terms of discharge rate, low temperature, and cycle life. The performance of the 12 V-class bipolar battery was comparable with that of conventional lithium-ion batteries with a liquid electrolyte, indicating that 12 V-class bipolar LTO/LMFP battery using the LLZ-based hybrid electrolyte has enough performance for practical uses. We are now trying to develop larger bipolar batteries for low-voltage system applications.

Differences in the recruitment curves obtained with monopolar and bipolar electrode configurations in the quadriceps femoris.

We sought to verify whether the stimulation intensity at which M-wave amplitude reaches a plateau actually corresponds to full motor unit activation in monopolar and bipolar configurations. M-waves and twitches were evoked using femoral nerve stimulation of gradually increasing intensity in 21 subjects. Recruitment curves corresponding to the amplitude of the first phase (AmpliFIRST ) and peak-to-peak amplitude (AmpliPP ) of the M-wave were obtained in the vastus lateralis, vastus medialis, and rectus femoris in monopolar and bipolar configurations. In all muscles, bipolar M-waves and twitches reached plateau at a significantly lower stimulus intensity compared with monopolar M-waves (P < 0.05). The different behavior of monopolar and bipolar M-waves with stimulus intensity was found for both AmpliFIRST and AmpliPP . In a bipolar configuration, the stimulus intensity at which M-waves plateau should be increased by at least 10%-20% to achieve complete motor unit recruitment. Muscle Nerve 54: 118-131, 2016.

ID 310 – Electromyography to protect the facial nerve during minimally invasive cochlear implantation

Objective In minimally invasive cochlear implantation (MICI) a tunnel is drilled towards the middle ear cavity and the facial nerve (FN) appears exposed in close proximity to the tool (0.3–1.2 mm). No method has been reported to ensure intraoperative FN protection during drilling. A custom designed stimulation probe could enable a safe mechanism for early detection of the facial nerve during MICI. Methods Per subject ( n = 5 sheep), 9 trajectories were drilled with different distances respect to the FN. Stimulus pulses with varying amplitude and duration were applied at 5 different depths. EMG responses were measured in the facial muscles. Measurements of drill to FN distance were achieved through μCT scans of the extracted temporal bones, postoperatively. A sensitivity and specificity analysis was performed for 3 stimulus threshold values (0.3, 0.5, 1 mA). Results 90% of the detections with the bipolar electrodes occurred at the FN boundary. The 1 mA intensity and the monopolar electrode provided early detection of the FN (>0.2 mm). Conclusion The newly developed probe has improved the sensitivity and specificity of FN detection during MICI. The results suggest that an insulated drill with monopolar stimulation at 1 mA would provide an early warning of FN detection above 0.2 mm.

Intra-operative electrooculographic monitoring to prevent post-operative extraocular motor nerve dysfunction during skull base surgeries.

Background and Aims:Intra-operative identification and preservation of extraocular motor nerves is one of the main goals of surgeries for skull base tumours and this is done by monitoring the extraocular movement (EOM). Intra-operative electromyographic monitoring has been reported, but it is a complex and skilful process. Electrooculography (EOG) is a simple and reliable technique for monitoring EOMs. We aimed to assess the utility of EOG monitoring in preventing extraocular motor nerve dysfunction during skull base surgeries.Methods:In this retrospective cohort study, intra-operative EOG recordings were obtained using disposable needle electrodes placed on the periorbital skin and the polarity of the waves noted for interpretation. Triggered as well as continuous EOG responses were recorded after monopolar electrode stimulation of cranial nerve (CN) during tumour removal which helped the surgeon with careful dissection and avoiding potential nerve injuries.Results:Of the 11 cases monitored, oculomotor and abducent nerves were identified in all cases, but the trochlear nerve could not be definitively identified. Six patients had no pre- or post-operative extraocular motor nerve dysfunction. The other five patients had pre-existing deficits before surgery, which recovered completely in two, significantly in one, and did not improve in two patients at 3–6 months follow-up.Conclusions:EOG was found to be a simple and reliable method of monitoring extraocular motor nerves (CNs III and VI) intraoperatively.

Effects of Subdural Monopolar Cortical Stimulation Paired With Rehabilitative Training on Behavioral and Neurophysiological Recovery After Cortical Ischemic Stroke in Adult Squirrel Monkeys

Background. Cortical stimulation (CS) combined with rehabilitative training (RT) has proven effective for enhancing poststroke functional recovery in rats, but human clinical trials have had mixed outcomes. Objective. To assess the efficacy of CS/RT versus RT in a nonhuman primate model of cortical ischemic stroke. Methods. Squirrel monkeys learned a pellet retrieval task, then received an infarct to the distal forelimb (DFL) representation of primary motor cortex. A subdural monopolar electrode was implanted over the spared DFL representation in dorsal premotor cortex (PMD). Seven weeks postinfarct, monkeys underwent 4 to 6 weeks of RT (n = 8) or CS/RT (n = 7; 100 Hz, cathodal current) therapy. Behavioral performance was assessed before and after infarct, prior to therapy, and 1 and 12 weeks posttherapy (follow-up). The primary outcome measure was motor performance at 1 week posttherapy. Secondary outcomes included follow-up performance at 12 weeks and treatment-related changes in neurophysiological maps of spared DFL representations. Results. While postinfarct performance deficits were found in all monkeys, both groups demonstrated similar recovery profiles, with no difference in motor recovery between the RT and CS/RT groups. Posttherapy, PMD DFL area was significantly expanded in the RT group but not the CS/RT group. A significant relationship was found between motor recovery and DFL expansion in premotor cortex. Conclusions. Results suggest that the specific parameters utilized here were not optimal for promoting behavioral recovery in nonhuman primates. Though CS/RT has consistently shown efficacy in rat stroke models, the present finding has cautionary implications for translation of CS/RT therapy to clinical populations.

Electronic enhancement of tear secretion

Objective. To study electrical stimulation of the lacrimal gland and afferent nerves for enhanced tear secretion, as a potential treatment for dry eye disease. We investigate the response pathways and electrical parameters to safely maximize tear secretion. Approach. We evaluated the tear response to electrical stimulation of the lacrimal gland and afferent nerves in isofluorane-anesthetized rabbits. In acute studies, electrical stimulation was performed using bipolar platinum foil electrodes, implanted beneath the inferior lacrimal gland, and a monopolar electrode placed near the afferent ethmoid nerve. Wireless microstimulators with bipolar electrodes were implanted beneath the lacrimal gland for chronic studies. To identify the response pathways, we applied various pharmacological inhibitors. To optimize the stimulus, we measured tear secretion rate (Schirmer test) as a function of pulse amplitude (1.5–12 mA), duration (0.1–1 ms) and repetition rate (10–100 Hz). Main results. Stimulation of the lacrimal gland increased tear secretion by engaging efferent parasympathetic nerves. Tearing increased with stimulation amplitude, pulse duration and repetition rate, up to 70 Hz. Stimulation with 3 mA, 500 μs pulses at 70 Hz provided a 4.5 mm (125%) increase in Schirmer score. Modulating duty cycle further increased tearing up to 57%, compared to continuous stimulation in chronically implanted animals (36%). Ethmoid (afferent) nerve stimulation increased tearing similar to gland stimulation (3.6 mm) via a reflex pathway. In animals with chronically implanted stimulators, a nearly 6 mm increase (57%) was achieved with 12-fold less charge density per pulse (0.06–0.3 μC mm−2 with 170–680 μs pulses) than the damage threshold (3.5 μC mm−2 with 1 ms pulses). Significance. Electrical stimulation of the lacrimal gland or afferent nerves may be used as a treatment for dry eye disease. Clinical trials should validate this approach in patients with aqueous tear deficiency, and further optimize electrical parameters for maximum clinical efficacy.

Constructing a three-dimensional electrical model of a living cochlear implant user's cochlea.

Hearing performance varies greatly among users of cochlear implants. Current three-dimensional cochlear models that predict the electrical fields inside a stimulated cochlea and their effect on neural excitation are generally based on a generic human or guinea pig cochlear shape that does not take inter-user morphological variations into account. This precludes prediction of user-specific performance. The aim of this study is to develop a model of the implanted cochlea of a specific living human individual and to assess if the inclusion of morphological variations in cochlear models affects predicted outcomes significantly. Five three-dimensional electric volume conduction models of the implanted cochleae of individual living users were constructed from standard CT scan data. These models were embedded in head models that include monopolar return electrodes in accurate anatomic positions. Potential distributions and neural excitation patterns were predicted for each of the models. Modeled potential distributions and neural excitation profiles (threshold amplitudes, center frequencies, and bandwidths) are affected by user-specific cochlear morphology and electrode placement within the cochlea. This work suggests that the use of user-specific models is indicated when more detailed analysis is required than what is available from generic models. Copyright © 2015 John Wiley & Sons, Ltd.

An effective method for improving electrocoagulation process: Optimization of Al 13 polymer formation

Abstract Al13 polymer has been believed to be the most active species responsible for coagulation. The character of Al species distribution and the formation of Al13 polymer in electrocoagulation (EC) process were investigated in order to provide insight into optimizing EC operation and design. The results indicated that predominant Al species shifted from monomer toward medium polymer then to larger polymer or Al(OH)(s) with increasing EC time. The in-situ Al13 polymer could be generated in EC process, and became the dominant species during 5–15 min. In EC process, Al13 species fraction positively correlated with the removal of turbidity and organic. The increase of pH and current density could accelerate the hydrolysis-polymerization process of Al3+. pH 5–7 and lowering current density favored the formation of Al13 polymer during EC process, EC process with bipolar electrodes had a higher yield of monomeric and Al13 species, while EC process with monopolar electrodes facilitated the formation of larger polymer or Al(OH)(s). The content of Al13 polymer can reach more than 60% under optimal conditions.

Ex Vivo Liver Experiment of Hydrochloric Acid-Infused and Saline-Infused Monopolar Radiofrequency Ablation: Better Outcomes in Temperature, Energy, and Coagulation.

To compare temperature, energy, and coagulation between hydrochloric acid-infused radiofrequency ablation (HAIRFA) and normal saline-infused radiofrequency ablation (NSIRFA) in ex vivo porcine liver model. 30 fresh porcine livers were excised in 60 lesions, 30 with HAIRFA and the other 30 with NSIRFA. Both modalities used monopolar perfusion electrode connected to a RF generator set at 103 °C and 30 W. In each group, ablation time was set at 10, 20, or 30 min (10 lesions from each group at each time). We compared tissue temperatures (at 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 cm away from the electrode tip), average power, deposited energy, deposited energy per coagulation volume (DEV), coagulation diameters, coagulative volume, and spherical ratio between the two groups. Temperature-time curves showed that HAIRFA provided progressively greater heating than that of NSIRFA. At 30 min, mean average power, deposited energy, coagulation volumes (113.67 vs. 12.28 cm(3)) and diameters, and increasing in tissue temperature were much greater with HAIRFA (P < 0.001 for all), except DEV was lower (456 vs. 1396 J/cm(3), P < 0.001). The spherical ratio was closer to 1 with HAIRFA (1.23 vs. 1.46). Coagulation diameters, volume, and average power of HAIRFA increased significantly with longer ablation times. While with NSIRFA, these characteristics were stable till later 20 min, except the power decreased with longer ablation times. HAIRFA creates much larger and more spherical lesions by increasing overall energy deposition, modulating thermal conductivity, and transferring heat during ablation.

Does the type of ablation device influence on the results of the treatment of atrial fibrillation in open heart surgery?

We analysed results of different types of monopolar and bipolar radiofrequency (RF) ablation in the surgical correction of valvular heart disease. From 2007 to 2011, RF ablation procedure performed 283 patients with atrial fibrillation and heart valve disease. Depending on the type of ablation electrode, all patients were divided into three groups: 64 (22.6%) cases monopolar ablation (MA), irrigated bipolar electrode (IBE) was used in 83 (29.3%) cases and dry bipolar ablation (DBA) formed 136 (48.1%). Time of ablation schemes using a monopolar electrode was significantly more, what increased time of aortic cross-clamping and cardiopulmonary bypass. No significant differences in the time parameters for groups of IBE and DBA has been received. Mortality in the hospital stay was not significantly different between the groups, reaching for the MA, IBE and DBA groups 1.5, 1.2 and 2.2% (p = 0.957; p = 0.784; p = 0.139). In neither case death was not directly related to the ablation procedure and type of electrode. Freedom from AF and AT in groups using bipolar ablative devices was significantly higher at all stages of the assessment results, amounting to MA, IBE and DBA groups, 68.1%, 84.0% and 85,7% respectively (log-rank test, p = 0.012 to DBA group and p = 0.021 for Group IBE). No significant differences between the use of irrigated electrodes and execution of the dry ablation were found (log-rank test, p = 0.249).

Oleuropein Improves Long Term Potentiation at Perforant Path-dentate Gyrus Synapses in vivo

ObjectiveTo investigate the effect of oleuropein (OE) on long term potentiation (LTP) at hippocampal perforant path-dentate gyrus synapses in vivo. MethodsAn outer guide cannula, a monopolar recording electrode, and a bipolar stimulating electrode were implanted in the skull and extracellular recording technique was used to record the population spike in the dentate gyrus of anesthetized rats. ResultsOleuropein significantly increased the basal synaptic transmission and the amplitude of population spike was increased from (117.6 ± 2.3)% to (134.9 ± 3.7)% after administration with OE. OE also accelerated LTP induction and maintenance, the population spike amplitude after high frequency stimulation was increased from (167.2 ± 12.8)% to (225.5 ± 15.5)% and the maintenance phase of LTP was from (182.1 ± 15.1)% to (210.5 ± 9.0)% respectively after administration with OE. ConclusionPresent study showed that OE significantly improved different stages of LTP, which could be the molecular mechanism of its efficacy on attenuating AD-like pathology and delaying cognitive decline. OE can be a promising drug for AD and dementia.