BACKGROUND: Electrical stimulation involving temporal interference of two different kHz frequency sinusoidal electric fields (temporal interference (TI)) enables non-invasive deep brain stimulation, by creating an electric field that is amplitude modulated at the slow difference frequency (within the neural range), at the target brain region. OBJECTIVE: Here, we investigate temporal interference neural stimulation using square, rather than sinusoidal, electric fields that create an electric field that is pulse-width, but not amplitude, modulated at the difference frequency (pulse-width modulated temporal interference, (PWM-TI)). METHODS/RESULTS: We show, using ex-vivo single-cell recordings and in-vivo calcium imaging, that PWM-TI effectively stimulates neural activity at the difference frequency at a similar efficiency to traditional TI. We then demonstrate, using computational modelling, that the PWM stimulation waveform induces amplitude-modulated membrane potential depolarization due to the membrane's intrinsic low-pass filtering property. CONCLUSIONS: PWM-TI can effectively drive neural activity at the difference frequency. The PWM-TI mechanism involves converting an envelope amplitude-fixed PWM field to an amplitude-modulated membrane potential via the low-pass filtering of the passive neural membrane. Unveiling the biophysics underpinning the neural response to complex electric fields may facilitate the development of new brain stimulation strategies with improved precision and efficiency.

• MeSH
• elektrická stimulace MeSH
• mozek * MeSH
• počítačová simulace MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Little is known about intracranial pressure (ICP)-cerebral haemodynamic interplay during repetitive apnoea. A recently developed method based on near-infrared transillumination/backscattering sounding (NIR-T/BSS) noninvasively measures changes in pial artery pulsation (cc-TQ) as well as subarachnoid width (sas-TQ) in humans. METHOD: We tested the complex response of the pial artery and subarachnoid width to apnoea using this method. The pial artery and subarachnoid width response to consecutive apnoeas lasting 30, 60 s and maximal breath-hold (91.1 ± 23.1 s) were studied in 20 healthy volunteers. The cc-TQ and sas-TQ were measured using NIR-T/BSS; cerebral blood flow velocity (CBFV), pulsatility index and resistive index were measured using Doppler ultrasound of the left internal carotid artery; heart rate (HR) and beat-to-beat SBP and DBP blood pressure were recorded using a Finometer; end-tidal CO2 (EtCO2) was measured using a medical gas analyser. RESULTS: Apnoea evoked a multiphasic response in blood pressure, pial artery compliance and ICP. First, SBP declined, which was accompanied by an increase in cc-TQ and sas-TQ. Directly after these changes, SBP exceeded baseline values, which was followed by a decline in cc-TQ and the return of sas-TQ to baseline. During these initial changes, CBFV remained stable. Towards the end of the apnoea, BP, cc-TQ and CBFV increased, whereas pulsatility index, resistive index and sas-TQ declined. Changes in sas-TQ were linked to changes in EtCO2, HR and SBP. CONCLUSION: Apnoea is associated with ICP swings, closely reflecting changes in EtCO2, HR and peripheral BP. The baroreflex influences the pial artery response.

• MeSH
• apnoe patofyziologie   MeSH
• arteria carotis interna ultrasonografie   MeSH
• arteriae cerebrales fyziologie   MeSH
• baroreflex MeSH
• dospělí MeSH
• intrakraniální tlak fyziologie   MeSH
• krevní tlak fyziologie   MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mozkový krevní oběh fyziologie   MeSH
• srdeční frekvence fyziologie   MeSH
• subarachnoidální prostor anatomie a histologie   fyziologie   MeSH
• ultrasonografie dopplerovská MeSH
• velikost orgánu MeSH
• zdraví dobrovolníci pro lékařské studie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

To call attention to the danger of extinction of the panda bear, the Lithuanian artist Ilja Klemencov created the artwork "They can disappear". The illustration is composed of black-and-white zigzagged lines, which form the famous panda logo of the World Wild Fund For Nature (WWF) when seen from a distance. If one is too close to the artwork, it is difficult to spot the bear, however, if one steps back or takes off one's glasses the panda suddenly appears. This led us to ask if the ability to see the panda is related to the visual acuity of the observer and if therefore, the panda illusion can be used to assess the spatial resolution of the eye. Here we present the results of the comparison between visual acuity determined using the Landolt C and that predicted from the panda illusion in 23 healthy volunteers with artificially reduced visual acuity. Furthermore, we demonstrate that the panda illusion is based on a 2D pulse-width modulation, explain its technical history, and provide the equations required to create the illusion. Finally, we explain why the illusion indeed can be used to predict visual acuity and discuss the neural causes of its perception with best-corrected visual acuity.

• MeSH
• dospělí MeSH
• iluze fyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• senioři MeSH
• zraková ostrost * MeSH
• zraková percepce fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND AND OBJECTIVE: Respiration is known to affect cerebrospinal fluid (CSF) movement. We hypothesised that increased inspiratory resistance would affect the dynamic relationship between blood pressure (BP) changes and subarachnoid space width (SAS) oscillations. METHODS: Experiments were performed in a group of 20 healthy volunteers undergoing controlled intermittent Mueller Manoeuvres (the key characteristic of the procedure is that a studied person is subjected to a controlled, increased inspiratory resistance which results in marked potentiation of the intrathoracic negative pressure). BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography; oxyhaemoglobin saturation with an ear-clip sensor; end-tidal CO2 with a gas analyser; cerebral blood flow velocity (CBFV), pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a new method i.e. near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the BP and SAS oscillations coupling. RESULTS: Initiating Mueller manoeuvres evoked cardiac SAS component decline (-17.8%, P<0.001), systolic BP, diastolic BP and HR increase (+6.3%, P<0.001; 6.7%, P<0.001 and +2.3%, P<0.05, respectively). By the end of Mueller manoeuvres, cardiac SAS component and HR did not change (+2.3% and 0.0%, respectively; both not statistically significant), but systolic and diastolic BP was elevated (+12.6% and +8.9%, respectively; both P<0.001). With reference to baseline values there was an evident decrease in wavelet coherence between BP and SAS oscillations at cardiac frequency in the first half of the Mueller manoeuvres (-32.3%, P<0.05 for left hemisphere and -46.0%, P<0.01 for right hemisphere) which was followed by subsequent normalization at end of the procedure (+3.1% for left hemisphere and +23.1% for right hemisphere; both not statistically significant). CONCLUSIONS: Increased inspiratory resistance is associated with swings in the cardiac contribution to the dynamic relationship between BP and SAS oscillations. Impaired cardiac performance reported in Mueller manoeuvres may influence the pattern of cerebrospinal fluid pulsatility.

• MeSH
• dospělí MeSH
• dýchání * MeSH
• krevní tlak fyziologie   MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mozkový krevní oběh fyziologie   MeSH
• rychlost toku krve fyziologie   MeSH
• srdeční frekvence fyziologie   MeSH
• subarachnoidální prostor diagnostické zobrazování   fyziologie   MeSH
• ultrasonografie dopplerovská transkraniální MeSH
• zdraví dobrovolníci pro lékařské studie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Ultrabrief stimulation in electroconvulsive therapy (ECT) using a 0.25 or 0.30 ms pulse width markedly reduces the charge required to reach the seizure threshold (ST) and cognitive side effects. It is not known whether further reduction of pulse width to 0.15 ms is advantageous. METHODS: Thirty-seven patients were randomized to ST titration at the first session applying right unilateral (RUL) ECT with either a 0.15 or 0.30 ms pulse width and were titrated again in the second session using the alternative pulse width. All subsequent treatments used the pulse width applied in the second titration session, administering RUL ECT, starting at 6xST. The primary outcome was difference between the pulse widths in ST at the two titration sessions. Exploratory analyses examined differences in seizure duration and postictal time to recover orientation (TRO), averaged across all ECT sessions from the third onwards. Other exploratory analyses examined clinical improvement and retrograde amnesia for autobiographical information and other neuropsychological functions following the ECT course. RESULTS: In the first titration session, ST was significantly lower with the 0.15 ms than 0.30 ms pulse width. ST significantly increased when re-titrating with the 0.30 ms pulse width and significantly decreased when re-titrating with a 0.15 ms pulse width. There were no differences between the pulse width groups in clinical improvement, TRO, or neuropsychological measures. CONCLUSIONS: Ultra-ultrabrief stimulation with a 0.15 ms pulse width is more efficient in seizure induction than a 0.30 ms pulse width. Comprehensive studies should determine whether ultra-ultrabrief stimulation replaces ultrabrief stimulation as a default parameter for ECT.

• MeSH
• dospělí MeSH
• elektrokonvulzívní terapie * metody   škodlivé účinky   MeSH
• lidé středního věku MeSH
• lidé MeSH
• senioři MeSH
• výsledek terapie MeSH
• záchvaty terapie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• randomizované kontrolované studie MeSH
• srovnávací studie MeSH

Background and objectives: For the treatment of chronic unilateral radicular syndrome, there are various methods including three minimally invasive computed tomography (CT)-guided methods, namely, pulsed radiofrequency (PRF), transforaminal oxygen ozone therapy (TFOOT), and transforaminal epidural steroid injection (TFESI). Despite this, it is still unclear which of these methods is the best in terms of pain reduction and disability improvement. Therefore, the purpose of this study was to evaluate the short and long-term effectiveness of these methods by measuring pain relief using the visual analogue scale (VAS) and improvement in disability (per the Oswestry disability index (ODI)) in patients with chronic unilateral radicular syndrome at L5 or S1 that do not respond to conservative treatment. Materials and Methods: After screening 692 patients, we enrolled 178 subjects, each of whom underwent one of the above CT-guided procedures. The PRF settings were as follows: pulse width = 20 ms, f = 2 Hz, U = 45 V, Z ˂ 500 Ω, and interval = 2 × 120 s. For TFOOT, an injection of 4-5 mL of an O2-O3 mixture (24 μg/mL) was administered. For the TFESI, 1 mL of a corticosteroid (betamethasone dipropionate), 3 mL of an anaesthetic (bupivacaine hydrochloride), and a 0.5 mL mixture of a non-ionic contrast agent (Iomeron 300) were administered. Pain intensity was assessed with a questionnaire. Results: The data from 178 patients (PRF, n = 57; TFOOT, n = 69; TFESI, n = 52) who submitted correctly completed questionnaires in the third month of the follow-up period were used for statistical analysis. The median pre-treatment visual analogue scale (VAS) score in all groups was six points. Immediately after treatment, the largest decrease in the median VAS score was observed in the TFESI group, with a score of 3.5 points (a decrease of 41.7%). In the PRF and TFOOT groups, the median VAS score decreased to 4 and 5 points (decreases of 33% and 16.7%, respectively). The difference in the early (immediately after) post-treatment VAS score between the TFESI and TFOOT groups was statistically significant (p = 0.0152). At the third and sixth months after treatment, the median VAS score was five points in all groups, without a statistically significant difference (p > 0.05). Additionally, there were no significant differences in the Oswestry disability index (ODI) values among the groups at any of the follow-up visits. Finally, there were no significant effects of age or body mass index (BMI) on both treatment outcomes (maximum absolute value of Spearman's rank correlation coefficient = 0.193). Conclusions: Although the three methods are equally efficient in reducing pain over the entire follow-up, we observed that TFESI (a corticosteroid with a local anaesthetic) proved to be the most effective method for early post-treatment pain relief.

• MeSH
• injekce epidurální MeSH
• kyslík MeSH
• lidé MeSH
• ozon * terapeutické užití   MeSH
• pulsní radiofrekvenční terapie * MeSH
• radikulopatie * farmakoterapie   MeSH
• výsledek terapie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

AIMS: A dual-chamber leadless pacemaker (LP) system that employs distinct atrial and ventricular LP devices (ALP, VLP) has been introduced to clinical practice. Proprietary, low-energy, implant-to-implant (i2i) communication at each beat enables the devices to maintain synchronous atrioventricular sensing and pacing. We evaluated device longevities and contributing factors, such as i2i communication. METHODS AND RESULTS: Patients meeting dual-chamber pacing indications received the dual-chamber LP system as part of a prospective, multi-centre, international clinical trial (Aveir DR i2i Study, NCT05252702). Programming and diagnostics were interrogated from all de novo, non-revised, dual-chamber programmed devices at 12 months post-implant. This analysis included 302 patients (65% male; age 70 ± 13 years; weight 80 ± 19 kg; intrinsic heart rate 55 ± 7 bpm; 58% sinus node dysfunction, 27% atrioventricular block). At 12 months, devices were programmed to dual-chamber pacing (DDD(R) or DDI(R)) at a median 60 bpm rate, median 1.25 V pulse amplitude in ALP and 1.5 V in VLP, median 0.4 ms pulse width, and median i2i signal setting level 5 out of 7. Median ALP and VLP remaining battery longevities at 12 months were 4.3 and 9.1 years, with median total ALP and VLP longevities of 5.3 and 9.9 years. Base rate, pulse amplitude, pacing percentage, event rate, impedance, and i2i setting level all exhibited significant correlations with ALP and VLP longevities (P < 0.001). Programming i2i setting levels below 7 produced the greatest longevity savings. CONCLUSION: The first dual-chamber LP demonstrated adequate projected battery longevity after 12 months of use. Patient-specific device programming considerations, unique to leadless devices, may extend longevity.

• MeSH
• atrioventrikulární blokáda terapie   diagnóza   patofyziologie   MeSH
• časové faktory MeSH
• design vybavení MeSH
• kardiostimulace umělá * metody   MeSH
• kardiostimulátor * MeSH
• lidé středního věku MeSH
• lidé MeSH
• prospektivní studie MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• srdeční arytmie * terapie   diagnóza   patofyziologie   MeSH
• srdeční frekvence MeSH
• výsledek terapie MeSH
• zdroje elektrické energie * MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky MeSH
• multicentrická studie MeSH

Cíl: Cílem studie bylo provést analýzu expozičních parametrů skiagrafického a skiaskopického módu, a porozumět tak fungování expoziční automatiky angiografického systému, který je využíván pro intervenční kardiologické výkony. Dále bylo cílem zhodnotit vliv přídavné filtrace na dávku pacientům. Metoda: Studie byla provedena pro systém Axiom Artis MP se zesilovačem obrazu. Do analýzy byly zahrnuty expoziční parametry plynoucí z funkce expoziční automatiky pro několik skiagrafických módů používaných pro dospělé pacienty, ale stejně tak pro módy používané v pediatrii. Jednalo se hlavně o analýzu následujících parametrů: napětí rentgenky, proud rentgenky, šířka pulzu a přídavná filtrace. Výsledky: Hlavní rozdíl mezi expozičními parametry pro SG a SS režim byl zjištěn pro proud rentgenky a šířku pulzu, menší rozdíl pak pro přídavnou filtraci. Pro AEC platí, že s rostoucí tloušťkou fantomu se zvyšuje nejprve proud rentgenky, šířka pulzu a napětí zůstává konstantní. Při dalším zvětšení tloušťky fantomu narůstá proud a šířka pulzu, napětí je udržováno na konstantní hodnotě. Při ještě větší tloušťce fantomu se zvyšuje i použité napětí a současně se zmenšuje přídavná filtrace. Závěr: Expoziční parametry skiagrafického módu se odlišují od parametrů skiaskopického módu. Skiaskopický mód pracuje s nižším proudem a vyšší filtrací, což znamená snížení dávky na kůži pacientů, ale současně je to spojeno s méně kvalitním obrazem. Použití větší přídavné filtrace není možné pro obézní pacienty kvůli nadměrnému zatížení rentgenky.

Aim: The aim of this work was to analyse exposure parameters of cine mode and fluoroscopy mode and therefore to understand the automatic exposure control of an angiography system used for interventional cardiology procedures. The influence of the additional filtration on dose to patients was assessed. Methods: The study was performed on the angiography system Axiom Artis MP with an image intensifier. Exposure parameters selected by the automatic exposure control of many cine modes for adult patients as well as for pediatrie patients were analysed. Mainly it included tube voltage, tube current, pulse width and additional filtration. Results: The main difference between cine mode and fluoroscopy mode was in used tube current and pulse width, smaller difference was between additional filtration. With increasing thickness of the phantom, the AEC makes the tube current increase, pulse width and voltage is kept constant. With still increasing phantom width, current and pulse width increase, voltage is kept constant. Then tube current, pulse width and also voltage increase. With voltage increased, the additional filtration is lowered. Conclusion: The exposure parameters of cine mode were a little bit different from parameters of fluoroscopy mode. Thicker additional filtration significantly lowers the skin dose to patients but cannot be used for obese patients due to excessive X-ray tube loading.

• MeSH
• angiografie * škodlivé účinky   účinky záření   MeSH
• angioskopie škodlivé účinky   MeSH
• dávka záření * MeSH
• fantomy radiodiagnostické škodlivé účinky   využití   MeSH
• fluoroskopie škodlivé účinky   MeSH
• intervenční radiografie metody   normy   škodlivé účinky   MeSH
• intervenční radiologie metody   MeSH
• lidé MeSH
• radiační ochrana metody   normy   MeSH
• radiometrie metody   využití   MeSH
• vylepšení rentgenového snímku * metody   normy   přístrojové vybavení   MeSH
• Check Tag
• lidé MeSH

Scarcity of medical resources inspired many teams worldwide to design ventilators utilizing different approaches during the recent COVID-19 pandemic. Although it can be relatively easy to design a simple ventilator in a laboratory, a large scale production of reliable emergency ventilators which meet international standards for critical care ventilators is challenging and time consuming. The aim of this study is to propose a novel and easily manufacturable principle of gas mixing and inspiratory flow generation for mechanical lung ventilators. Two fast ON/OFF valves, one for air and one for oxygen, are used to control the inspiratory flow generation using pulse width modulation. Short gas flow pulses are smoothed by low-pass acoustic filters and do not propagate further into the patient circuit. At the same time, the appropriate pulse width modulation of both ON/OFF valves controls the oxygen fraction in the generated gas mixture. Tests focused on the accuracy of the delivered oxygen fractions and tidal volumes have proved compliance with the international standards for critical care ventilators. The concept of a simple construction using two fast ON/OFF valves may be used for designing mechanical lung ventilators and thus suitable for their rapid production during pandemics.

• MeSH
• COVID-19 * terapie   MeSH
• hromadné neštěstí * MeSH
• kyslík MeSH
• lidé MeSH
• mechanické ventilátory MeSH
• pandemie MeSH
• péče o pacienty v kritickém stavu MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Pulsed field ablation (PFA) can be myocardium selective, potentially sparing the esophagus during left atrial ablation. In an in vivo porcine esophageal injury model, we compared the effects of newer biphasic PFA with radiofrequency ablation (RFA). METHODS: In 10 animals, under general anesthesia, the lower esophagus was deflected toward the inferior vena cava using an esophageal deviation balloon, and ablation was performed from within the inferior vena cava at areas of esophageal contact. Four discrete esophageal sites were targeted in each animal: 6 animals received 8 PFA applications/site (2 kV, multispline catheter), and 4 animals received 6 clusters of irrigated RFA applications (30 W×30 seconds, 3.5 mm catheter). All animals were survived to 25 days, sacrificed, and the esophagus submitted for pathological examination, including 10 discrete histological sections/esophagus. RESULTS: The animals weight increased by 13.7±6.2% and 6.8±6.3% (P=0.343) in the PFA and RFA cohorts, respectively. No PFA animals (0 of 6, 0%) developed abnormal in-life observations, but 1 of 4 RFA animals (25%) developed fever and dyspnea. On necropsy, no PFA animals (0 of 6, 0%) demonstrated esophageal lesions. In contrast, esophageal injury occurred in all RFA animals (4 of 4, 100%; P=0.005): a mean of 1.5 mucosal lesions/animal (length, -21.8±8.9 mm; width, -4.9±1.4 mm) were observed, including one esophago-pulmonary fistula and deep esophageal ulcers in the other animals. Histological examination demonstrated tissue necrosis surrounded by acute and chronic inflammation and fibrosis. The necrotic RFA lesions involved multiple esophageal tissue layers with evidence of arteriolar medial thickening and fibrosis of periesophageal nerves. Abscess formation and full-thickness esophageal wall disruptions were seen in areas of perforation/fistula. CONCLUSIONS: In this novel porcine model of esophageal injury, biphasic PFA induced no chronic histopathologic esophageal changes, while RFA demonstrated a spectrum of esophageal lesions including fistula and deep esophageal ulcers and abscesses.

• MeSH
• ezofágus zranění   MeSH
• fibrilace síní chirurgie   MeSH
• katetrizační ablace škodlivé účinky   metody   MeSH
• modely nemocí na zvířatech MeSH
• pooperační komplikace etiologie   prevence a kontrola   MeSH
• prasata MeSH
• srdeční síně chirurgie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH