Neuromodulación eléctrica en el tratamiento del dolor neuropático refractario. Colocación del primer estimulador medular en Cuba / Electric neuromodulation in the treatment of refractory pain. Placement of the first spinal stimulator in Cuba

El dolor es una causa importante de sufrimiento físico y emocional. El tratamiento médico de los pacientes con dolor crónico refractario es un gran reto. Se presenta el caso de una paciente de 19 años con un cuadro radicular compresivo secundario a Hernia discal L5-S1 derecha, que se le aplicó una discectomía L5-S1 por técnica de Caspar. Al mes de evolución regresa con igual sintomatología. A pesar de múltiples terapias farmacológicas y procederes intervencionistas, el dolor neuropático no mejora, después de múltiples estudios y discusiones en colectivo se determina la posibilidad de la colocación de un neuroestimulador medular, proceder que se lleva a cabo con mejoría considerable de su cuadro doloroso(AU)

Pain is a major cause of physical and emotional suffering. The management of patients with refractory chronic pain is a great challenge. The case is presented of a 19-year-old female patient with compressive radicular symptoms secondary to right L5-S1 disc herniation, who underwent L5-S1 discectomy with Caspar technique. After one month of evolution, she returned with the same symptoms. Despite multiple pharmacological therapies and interventional procedures, the neuropathic pain did not improve. After multiple studies and collective discussions, the possibility of placing a spinal neurostimulator was decided. After the procedure, the patient improved considerably with respect to her painful symptoms(AU)

Treatment of refractory left sided Ulcerative colitis: lessons from the Sages IBD registry

ABSTRACT Background: Left sided ulcerative colitis is often a severe disease which requires aggressive medical therapy. Rarely, it canresult in colectomy. Moreover, it can progress and extent to involve the entire colon. Method: Retrospective analysis of patient data on the SAGES IBD database. Patient data with severe left sided ulcerative colitis requiring anti-TNF therapy for the period between September 2016 to August 2017. Patient consent was obtained. Results: A total of 149 requests for biologic therapy were received during this period of which 13 had left sided ulcerative colitis. Seven (53.4%) were male and the mean age at diagnosis 33.3 years. Mean age at commencement of biologic therapy was 40.9 years. There were no smokers. One (7.7%) had ulcerative proctitis, 7 (53.8%) had proctosigmoiditis and 5 (38.4%) had left sided colitis. No patient was receiving topical steroids and 2 (15.4%) patients had exposure to topical 5-aminosalicylic acid. All patients had exposure to oral 5 aminosalicylic acid and 9 (69.2%) were receiving ongoing treatment. Ten (76.9%) received azathioprine or 6-mercaptopurine and 5 (38.5%) received methotrexate. Of the 12 patients on immunomodulator therapy, 10 (76.9) were concurrently on 5-aminosalicylic acid. Seven (53.8%) patients received infliximab and 9 (69.2%) patients received adalimumab. No one received golimumab or vedolizumab. All patients received standard dose anti-TNF therapy except 1 (7.7%) patient who received double dose infliximab. Biologic therapy was well tolerated with good clinical outcome and no side-effects. Conclusion: The incidence of severe left sided ulcerative colitis was low in this cohort. Severe left sided disease is associated with a high medication burden and cost. Response to biologic therapy was excellent

Alteración de las fibras finas A-delta por entrampamiento del nervio mediano en la muñeca utilizando el período silente cutáneo / The impairment of A-delta fibers in median nerve compression at the wrist, using the cutaneous silent period

El síndrome del túnel carpiano (STC) es una neuropatía por entrampamiento a nivel de la muñeca que cursa con dolor, parestesias y disestesias dolorosas. El diagnóstico electrofisiológico se basa en el estudio de la neuroconducción de las fibras gruesas. Nuestra hipótesis consiste en la existencia del compromiso de las fibras nerviosas finas y que este compromiso se correlaciona con el grado de gravedad. Se evaluaron retrospectivamente 69 manos correspondientes a 47 pacientes, varones y mujeres (edad media 53.8, rango 22-87 años) y como grupo contro, 21 manos correspondientes a los lados asintomáticos de estos casos. Se realizaron estudios de neuroconducción motora, sensitiva y ondas F para clasificar a las manos según el grado de gravedad. Se realizó el período silente cutáneo (PSC) en todas las manos. Se evaluaron latencias medias y duraciones medias del PSC. Las latencias medias se hallaron significativamente prolongadas en las manos con neuropatía (84.3 ± 16.3 mseg) con respecto a las manos sin neuropatía (74.8 ± 11.6 mseg), p < 0.05. Las latencias medias se hallaron más prolongadas en las manos con neuropatía de mayor gravedad (p < 0.05). En los 3 pacientes con neuropatía grado más grave no se halló el PSC. Se demostró el compromiso de las fibras finas A-delta en los pacientes con STC, con mayor compromiso a mayor severidad. El PSC puede usarse como complemento de los estudios de neuroconducción motora y sensitiva.

Carpal tunnel síndrome (CTS) is an entrapment neuropathy of the median nerve at the wrist, that leads to pain, paresthesia and painful dysesthesia. The electrophysiological diagnosis is based upon nerve conduction studies which evaluate thick nerve fibers. Our hypothesis is that there is an additional dysfunction of small fibers in CTS, which correlates with the degree of severity of the neuropathy. A retrospective study of 69 hands that belonged to 47 patients of both sexes (mean age 53.8, years, range 22-87) was performed, and, as a control group, 21 hands which corresponded to the asymptomatic side of those patients were evaluated. Motor and sensory conduction studies, as well as F-waves were performed to classify the neuropathy according to the degree of severity. Cutaneous silent period (CSP) was elicited in all hands. Mean onset latencies and durations of CSP were evaluated. Mean onset latencies were significantly prolonged in neuropathic hands (84.3 ± 16.3 msec) compared to asymptomatic hands (74.8 ± 11.6 msec) (p < 0.05). Mean latencies of the CSP were even prolonged (p < 0.05) in hands affected by a more severe neuropathy. In the 3 hands with most severe neuropathy, a CSP could not be elicited. In CTS an impairment of A-delta fibers was recorded through the CSP. The more severe the neuropathy is, the more impairment of A-delta fibers can be found. CSP may be assessed as a complement of motor and sensory nerve conduction studies in this neuropathy.

Tratamento cirúrgico da epilepsia refratária: análise de 34 casos atendidos no Hospital das Clínicas da UFMG / Surgical treatment of refractory epilepsy: analysis of 34 cases from the Hospital das Clínicas, Federal University of Minas Gerais

Objetivo: Apresentar dados estatísticos referentes a uma série de casos submetidos ao tratamento cirúrgico da epilepsia refratária no Hospital das Clínicas da Universidade Federal de Minas Gerais (HC-UFMG), no período entre 23/11/2007 e 7/12/2010. Métodos: Estudo retrospectivo com análise de prontuários de 34 pacientes e classificação do controle de crises pós-operatório utilizando a Escala de Engel. Resultados: Dos pacientes, 70,5% apresentaram início das crises antes dos 15 anos, sendo o tipo de crise mais comum as crises parciais complexas com generalização secundária, presente em 55% dos casos. Esclerose mesial temporal foi o diagnóstico de base em 79,4% dos pacientes. Houve complicações cirúrgicas em 23,5% dos casos, sendo as mais frequentes as alterações de campo visual (8,8% dos casos). Conclusão: O controle de crises foi compatível com Engel menor ou igual a III em 64,7% dos casos. O tratamento cirúrgico revelou-se eficiente para melhorar o controle de crises em pacientes portadores de epilepsia refratária ao tratamento medicamentoso.

Objective: Presenting statistical data on a series of cases undergoing surgical treatment of epilepsy at the Hospital das Clínicas, Universidade Federal de Minas Gerais (HC-UFMG) in the period between 11/23/2007 and 12/7/2010. Methods: Retrospective analysis with charts of 34 patients and classification of seizure control postoperatively using the Engel Scale. Results: 70.5% of the patients had the onset of seizures before 15 years old and the most common type of seizure was complex partial seizure with secondary generalization, presented in 55% of cases. Mesial temporal sclerosis was the underlying diagnosis in 79.4% of patients. There were surgical complications in 23.5% of cases, the most frequent visual changes (8.8% of cases). Conclusion: Seizure control was consistent with Engel III or less in 64.7% of cases. Surgical treatment has proved effective in improving seizure control in patients with medically refractory epilepsy.

The synergistic effect of gentamicin and clindamycin on rocuronium-induced neuromuscular blockade / 대한마취과학회지

BACKGROUND: Gentamicin reduces acetylcholine release and clindamycin causes end-plate ion channel blockade. Because of these reasons, two drugs show muscular relaxant effect and potentiate the action of nondepolarizing neuromuscular agents. This study was intended to evaluate the effect of gentamicin and clindamycin on rocuronium-induced neuromuscular blockade and the interaction between these drugs. METHODS: Male Sprague-Dawley rats' phrenic nerves and diaphragms were installed in a bath containing Krebs solution. They were divided into three study groups. The first group was pre-treated with 0.1 (n = 3), 0.2 (n = 4) or 0.5 (n = 3) mM gentamicin and the tension was measured as the concentration of rocuronium was increased. The second group was experimented by increasing gentamicin on 0.25 (n = 5), 0.5 (n = 6) or 1.0 (n = 6) mM clindamycin. The final group was pre-treated with various combinations of gentamicin and clindamycin. The drug concentration was gradually increased until single twitch tension decreased by around 80%. Effective concentration was calculated using a probit model and interaction indices derived the Loewe additivity. RESULTS: The administration of gentamicin and the combination of gentamicin and clindamycin enhanced rocuronium-induced neuromuscular blockade. At 0.2 and 0.5 mM gentamicin, synergistic interactions with rocuronium were observed. Likewise, at 0.5 and 1.0 mM clindamycin, synergistic interactions with gentamicin appeared. When all three drugs were combined, in the tetanic fade, all the groups except for those administered with 0.01 mM gentamicin and 0.25 mM clindamycin showed synergistic interactions. CONCLUSIONS: This study demonstrate that gentamicin and clindamycin potentiated rocuronium induced neuromuscular blockade. Moreover, it was found that these drugs interacted synergistically.

At therapeutic concentration bupivacaine causes neuromuscular blockade and enhances rocuronium-induced blockade / 대한마취과학회지

BACKGROUND: Partially paralyzed patients may be placed in the risk of pharyngeal dysfunction. Bupivacaine acts as acetylcholine receptor ion channel blocker and may synergistically interact with rocuronium to augment NM blockade. Thus, this study aims to elucidate whether or not, at a therapeutic concentration, bupivacaine by itself may cause NM blockade and reduce an effective concentration of rocuronium. METHODS: Twenty-two left phrenic nerve-hemidiaphragms (Male SD rats, 150-250 g) were hung in Krebs solution. Three consecutive ST, 0.1 Hz and one TT, 50 Hz for 1.9 s were obtained before drug application and at each new drug concentration. A concentration of bupivacaine in Krebs solution (n = 5) was cumulatively increased by way of 0.01, 0.1, 1, (1, 2, 3, 4, 5, 6, 7) x 10 microM. In a Krebs solution, pre-treated with bupivacaine 0 (n = 5), 0.1 (n = 5), 1.0 (n = 5), 10 (n = 2) microM, and then concentrations of rocuronium were cumulatively increased by way of 1, 3, 5, 7, 9, 12, 14, 16, 18, 20 microM. EC for each experiment were determined by a probit. The EC50's of rocuronium were compared using a Student's t-test with Bonferroni's correction. Differences were considered significant when P < 0.05. RESULTS: The potency of bupivacaine for normalized TF was 11.4 (+/- 1.1) microM. Below 30 microM of bupivacaine, the single twitch potentiation sustained despite the development of tetanic fade and partial inhibition of PTT. Bupivacaine significantly facilitated the NM blockade induced by rocuronium. CONCLUSIONS: Clinicians should be aware that bupivacaine by itself at its therapeutic concentration inhibit NM conduction and enhances rocuronium-induced muscle relaxation.

Effects and the mechanisms of cardiac short-term memory on cellular electrical excitability / 生物医学工程学杂志

Electrical instability easily induces a unidirectional conduction block, resulting in ventricular tachycardia (VT) or even fibrillation (VF). Cardiac memory affects dynamic electrical characteristics through previous pacing so that it makes the memory important in arrhythmia study. This paper investigates the impact of the rapid pacing duration on cellular excitability and its mechanism. Based on the canine endocardial single cell, a one-dimensional tissue model was developed. Simulations were realized with OpenMP parallel programming method. The results showed that with repetitive pacing, the cellular excitability became low while the conduction velocity decreased. Accumulation of intracellular [Ca2+]i and [Na+]i and depletion of [K+]i led to the shift of membrane current-voltage curves, changing the membrane resistance. Excitability determined by the resistance at the large width of stimulus pulse, therefore, it suggested that [Ca2+]i and [K+]i-induced memory formed the ionic substrates for the alteration of excitability.

The antagonistic effect of neostigmine on rocuronium-, clindamycin-, or both-induced neuromuscular blocking in the rat phrenic nerve-hemidiaphragm / 대한마취과학회지

BACKGROUND: Neostigmine augments clindamycin-induced neuromuscular block and antagonizes rocuronium-induced neuromuscular block; however, it remains unclear whether neostigmine enhances the neuromuscular blocking (NMB) that is caused by combinations of rocuronium and clindamycin. The intent of this study was to determine whether neostigmine potentiates the muscle relaxation that is induced by combinations of rocuronium and clindamycin and to estimate whether both clindamycin and rocuronium have synergistic actions on NMB. METHODS: Forty-one left phrenic nerve-hemidiaphragms (from male Sprague-Dawley rats, 150-250 g) were mounted in Krebs solution. Three consecutive single twitches (ST, 0.1 Hz) and one tetanic tension (50 Hz for 1.9 s) were obtained for each increase in concentration of rocuronium or clindamycin. The concentrations of rocuronium were cumulatively increased until an 80% to 90% reduction in ST was attained in the Krebs solutions pre-treated with 0 (n = 5), 0.1 (n = 1), 0.25 (n = 1), 0.5 (n = 4), or 1.0 (n = 1) mM clindamycin or with 0 (n = 4), 0.1 (n = 1), 0.5 (n = 5), 1.0 (n = 5), or 2.0 (n = 4) mM clindamycin in combination with 250 nM neostigmine, and so were the concentrations of clindamycin in the Krebs solutions pre-treated with 0 (n = 6) or 250 nM (n = 6) neostigmine. RESULTS: Clindamycin increased the potency of rocuronium for ST and tetanic fade, irrespective of the presence of neostigmine. Neostigmine shifted the concentration-response curve of rocuronium to the right in the presence or absence of clindamycin. The interaction between rocuronium and clindamycin was synergistic when clindamycin concentrations were in excess of 0.5 mM, irrespective of the presence of neostigmine. CONCLUSIONS: Neostigmine may partially antagonize the neuromuscular block that is induced by a combination of clindamycin and rocuronium. Clinicians are advised to be aware that clindamycin synergistically increases the degree of rocuronium-induced neuromuscular block, even when neostigmine is present.

Implante coclear: correlação da recuperação neural, privação auditiva e etiologia / Cochlear implant: correlation of nerve function recovery, auditory deprivation and etiology

TEMA: a Função de Recuperação do Nervo Auditivo (REC) pode ser extraída do potencial de ação das fibras neurais - ECAP (Eletrically Evoked Compound Action Potential). O ECAP pode ser influenciado pela estimulação recebida pelo nervo e pela etiologia de uma perda auditiva e, consequentemente, afetar a REC. OBJETIVO: verificar se há correlação entre REC e os fatores: etiologia, tempo de surdez e tempo de uso do AASI antes do Implante Coclear (IC). MÉTODO: estudo retrospectivo transversal. Foram coletados dados sobre etiologia, tempo de surdez, tempo de uso do Aparelho de Amplificação Sonora Individual (AASI) e REC de 50 indivíduos, 26 crianças e 24 adultos, submetidos à cirurgia de IC e usuários do dispositivo multicanal Nucleus®24. As medidas da função de recuperação do nervo auditivo foram calculadas e os pacientes foram divididos em grupos (GI: recuperação rápida, GII: recuperação intermediária e GIII: recuperação lenta) para posterior análise de relação com os demais dados coletados. RESULTADOS: a análise dos dados não mostrou correlação estatisticamente significante entre a recuperação e os aspectos pré-cirúrgicos estudados. Entretanto, foi possível observar maior concentração de ambos, crianças e adultos, nas REC intermediárias. GI não agrupou indivíduos com surdez de etiologias infecciosas, tais como a meningite, rubéola e citomegalovírus. A média de REC apresentou-se mais lenta para as etiologias infecciosas, tanto para o grupo de crianças, como para o grupo de adultos. CONCLUSÃO: não houve correlação estatisticamente significante entre função de recuperação do nervo auditivo e os fatores: etiologia, tempo de surdez e tempo de uso do AASI antes do IC.

BACKGROUND: the Auditory Nerve Recovery Function (REC) may be extracted from the Electrically Evoked Compound Action Potential (ECAP). ECAP may be influenced by the stimulation received (or the deprivation of stimulation) and by the etiology of the hearing loss, consequently it might affect the REC. AIM: to verify whether there is a correlation between the REC and each of the following factors: etiology, time of auditory deprivation and time of hearing aid use before cochlear implantation (CI). METHOD: retrospective study. Data regarding etiology, time of auditory deprivation, time of hearing aid use before cochlear implantation were collected in children and adults who received a Nucleus®24. All patients who presented neural response at surgery and whose REC was assessed intraoperatively were included in this study. Fifty patients were selected, 26 children and 24 adults. Patients were divided according to the REC classification into three groups (GI: fast recovery; GII: intermediate recovery and GIII: slow recovery) to allow correlation analysis. RESULTS: data analysis did not show any statistically significant correlation between the recovery function and the pre-implant studied characteristics. Nevertheless, it was observed that there was a greater concentration of both, children and adults, in the intermediate recovery function values. GI did not present individuals with infectious etiologies, such as meningitis, rubella and cytomegalovirus. REC average scores were slower in infectious etiologies for both children and adults. CONCLUSION: there was no statistically significant correlation between the recovery function and factors such as etiology, time of auditory deprivation and time of hearing aid use prior to CI.

Sound duration and sound pattern affect the recovery cycles of inferior collicular neurons in leaf-nosed bat, Hipposideros armiger / 生理学报

The effects of sound duration and sound pattern on the recovery cycles of inferior collicular (IC) neurons in constant frequency-frequency modulation (CF-FM) bats were explored in this study. Five leaf-nosed bats, Hipposideros armiger (4 males, 1 female, 43-50 g body weight), were used as subjects. The extracellular responses of IC neurons to paired sound stimuli with different duration and patterns were recorded, and the recovery was counted as the ratio of the second response to the first response. Totally, 169 sound-sensitive IC neurons were recorded in the experiment. According to the interpulse interval (IPI) of paired sounds when neurons reached 50% recovery (50% IPI), the recovery cycles of these IC neurons were classified into 3 types: fast recovery (F, the 50% IPI was less than 15 ms), short recovery (S, the 50% IPI was between 15.1 and 30 ms) and long recovery (L, the 50% IPI was more than 30 ms). When paired CF stimuli with 2 ms duration was used, the ratio of F neurons was 32.3%, and it decreased to 18.1% and 18.2% respectively when 5 and 7 ms CF stimuli were used. The ratios of S and L neurons were 41.5%, 33.7%, 29.1% and 26.2%, 48.2%, 52.7% respectively when 2, 5 and 7 ms CF stimuli were used. The average 50% IPI determined after stimulation with paired 2 ms, 5 ms and 7 ms CF sounds were (30.2 ± 27.6), (39.9 ± 29.1) and (49.4 ± 34.7) ms, respectively, and the difference among them was significant (P< 0.01). When the stimuli of paired 2 ms CF sounds were shifted to paired 2 ms FM sounds, the proportion of F, S and L neurons changed from 32.3%, 41.5%, 26.2% to 47.7%, 24.6%, 27.7%, respectively, and the average 50% IPI decreased from (30.2 ± 27.6) to (23.9 ± 19.0) ms (P< 0.05, n = 65). When paired 5+2 ms CF-FM pulses were used instead of 7 ms CF sounds, the proportion of F, S and L neurons changed from 18.2%, 29.1%, 52.7% to 29.1%, 27.3%, 43.6%, respectively, and the average 50% IPI decreased from (49.4 ± 34.7) to (36.3 ± 29.4) ms (P< 0.05, n = 55). All these results suggest that the CF and FM components in echolocation signal of CF-FM bats play different roles during bats' hunting and preying on. The FM component of CF-FM signal presenting in the terminal phase can increase the number of F type neurons and decrease the recovery cycles of IC neurons for processing high repetition echo information, which ensures the bat to analyze the target range and surface texture more accurately.

Clinical and electrophysiological predictors of ventriculoatrial conduction in patients under evaluation for ventricular tachyarrhythmia

Ventriculoatrial [VA] conduction has an important role in the initiation and maintenance of some arrhythmias. The aim of this study was to evaluate whether clinical and electrophysiological parameters of atrioventricular [A V] conduction can predict VA conduction. Detailed demographic, electrocardiographic, and echocardiographic data were recorded in 54 consecutive patients undergoing electrophysiological study for the evaluation of ventricular tachyarrhythmia. The basic parameters including atrial-His [AH] and His-ventricular [HV] intervals, atrioventricular Wenckebach point [AVWP], Ventriculoatrial Wenckebach point [VAWP], anterograde effective refractory period of atrioventricular node [AERP-AVN], retrograde effective refractory period of atrioventricular node [RERP-AVN] and effective refractory period of ventricle [VERP] were measured based on standard protocol. Mean age of the patients was 59.4 [ +/- 13.9] years. Forty-three [79.6%] patients were male and 39 [72.2%] had a history of ischemic heart disease. Ventriculoatrial [VA] conduction was recorded in 21 [38.9%] patients; it was slightly more prevalent in the men [44.2% vs. 18.2%; p value = 0.114]. In the patients without VA conduction, the means of AVWP, AERP-AVN, and PR intervals were significantly more prolonged [p value = 0.007, 0.030, and 0.045, respectively], and a trend toward more prolonged AH, HV, and QRS interval was seen in them [p value = 0.078, 0.124, and 0.159, respectively]., WWP was the best predictor for the absence of Ventriculoatrial [VA] conduction. Fifty [92.5%] patients had a better AV than VA conduction. Age, presence of ischemic heart disease, left ventricular ejection fraction, and diastolic function could ml predict VA conduction. A significant direct relationship was found between left ventricular ejection fraction and VAWP [p value = 0.036, r = 0.4; the Pear son correlation test]. Prediction of VA conduction based on clinical and echocardiographic characteristics is not possible. Impairment of AV conduction was the best predictor for the impairment ofVA conduction, and most patients had a better AV than/ km VA conduction. In this study, the men had a slightly higher prevalence of VA conduction

Remodelagem atrial elétrica reversa após cardioversão de fibrilação atrial isolada de longa duração / Remodelación atrial eléctrica reversa tras cardioversión de fibrilación atrial aislada de larga duración / Reversal atrial electrical remodeling following cardioversion of long-standing lone atrial fibrillation

FUNDAMENTO: A fibrilação atrial (FA) isolada promove mudanças eletrofisiológicas, chamadas de "remodelamento elétrico", facilitando sua recorrência e manutenção. Há evidência de que o processo de remodelamento seja reversível após a recuperação do ritmo sinusal (RS). Entretanto, o momento para a recuperação das propriedades eletrofisiológicas ainda não foi definido. OBJETIVO: O objetivo desse estudo foi avaliar a ativação elétrica atrial usando o eletrocardiograma de alta resolução de onda P (P-ECGAR) pós-cardioversão da FA de longa duração, concentrando-se no processo de remodelamento reverso para identificar o momento da estabilização do processo. MÉTODOS: Indivíduos com FA isolada persistente, candidatos à cardioversão com conversão bem-sucedida ao RS, foram incluídos no estudo. A P-ECGAR foi realizada imediatamente após a reversão ao ritmo sinusal e repetida após 7 e 30 dias. RESULTADOS: Dentre os 31 indivíduos, 9 apresentaram recorrência precoce da FA, todos nos primeiros 7 dias após a cardioversão, e 22 permaneceram em RS por pelo menos um mês; o ECGAR foi obtido no sétimo e no trigésimo dias após a cardioversão. No 30º dia, a duração da onda P progressivamente diminuiu do primeiro para o terceiro ECGAR (duração da onda P: 185,5±41,9 m/s vs 171,7±40,5 m/s vs 156,7±34,9 m/s, respectivamente, 1º, 2º e 3º ECGAR; p<0,001 para todas as comparações). Na análise de domínio de frequência, a turbulência espectral não foi aparente no ECGAR imediatamente após a cardioversão, mas aumentou de forma aguda no 7º dia e permaneceu inalterada no 30º dia. CONCLUSÃO: O presente estudo sugere que os primeiros sete dias pós-cardioversão, após FA de longa duração, são críticos para o processo de remodelamento reverso e recorrência da arritmia.

BACKGROUND: Atrial fibrillation (AF) itself promotes electrophysiological changes, termed "electrical remodeling", facilitating its recurrence and maintenance. There is evidence that the remodeling process is reversible after restoration of the sinus rhythm (SR). However, the timing for the recovery of electrophysiological properties is still undefined. OBJECTIVE: The aim of this study was to assess the atrial electrical activation using P-wave signal-averaged electrocardiogram (P-SAECG) post-cardioversion of long-standing AF, focusing on the reversal remodeling process to identify the timing of the process stabilization. METHODS: Subjects with lone persistent AF, eligible for cardioversion and successfully converted to SR, were enrolled at the study. SAECG was performed immediately after reversion to SR and repeated on days seven and thirty. RESULTS: Of 31 subjects, nine presented early recurrence of atrial fibrillation, all of them in the first seven days post-cardioversion; 22 remained in SR for at last one month and SAECG was obtained on days seven and thirty after cardioversion. In the latter, P-wave duration progressively abated from the first to the third SAECG (P-wave duration: 185.5±41.9 ms vs 171.7±40.5 ms vs 156.7±34.9 ms, respectively, first, second and third SAECG; p<0.001 for all matches). In the frequency domain analysis, spectral turbulence was not apparent in SAECG immediately post-cardioversion, but sharply increased on day seven and remained unchanged on day thirty. CONCLUSION: This study suggests that the first seven days post-cardioversion of long standing AF are critical for reversal remodeling process and arrhythmia recurrence.

FUNDAMENTO: La fibrilación atrial (FA) aislada promueve cambios electrofisiológicos llamados "remodelación eléctrica", que facilitan su recurrencia y mantenimiento. Hay evidencia de que el proceso de remodelación sea reversible tras la recuperación del ritmo sinusal (RS). Sin embargo, el momento para la recuperación de las propiedades electrofisiológicas no está definido todavía. OBJETIVO: El objetivo de ese estudio fue evaluar la activación eléctrica atrial con el empleo del electrocardiograma de alta resolución de onda P (P-ECGAR) postcardioversión de la FA de larga duración, concentrándose en el proceso de remodelación reversa para identificar el momento de la estabilización del proceso. MÉTODOS: Se incluyeron en el estudio a individuos con FA aislada persistente y a candidatos a la cardioversión con conversión exitosa al RS. La P-ECGAR se realizó inmediatamente tras la reversión al ritmo sinusal y se repitió después de 7 y 30 días. RESULTADOS: Entre los 31 individuos, 9 presentaron recurrencia precoz de la FA, todos en los primeros 7 días después de la cardioversión, y 22 siguieron en RS durante un mes como mínimo; el ECGAR se obtuvo en el séptimo y en el trigésimo días tras la cardioversión. En el 30º día, la duración de la onda P disminuyó progresivamente desde el primer hasta el tercer ECGAR (duración de la onda P: 185,5±41,9 m/s vs 171,7±40,5 m/s vs 156,7±34,9 m/s, respectivamente, 1er, 2º y 3er ECGAR; p<0,001 para todas las comparaciones). En los análisis de dominio de frecuencia, la turbulencia espectral no fue aparente en el ECGAR inmediatamente tras la cardioversión, pero aumentó de forma aguda en el 7º día y siguió inalterada en el 30º día. CONCLUSIÓN: El presente estudio sugiere que los primeros siete días post cardioversión, después FA de larga duración, son críticos para el proceso de remodelación reversa y recurrencia de la arritmia.

Analysis of the rocuronium-vecuronium interaction on tetanic fade based on a generalized response surface model with varying relative potencies / 대한마취과학회지

BACKGROUND: Some studies have shown that rocuronium and vecuronium have additive, or synergistic effects on muscle relaxation based on the Loewe additivity. Therefore, we performed a fit of tetanic fade data to a generalized response surface model with varying relative potencies proposed by Kong and Lee (KLGRS) to evaluate the usefulness of KLGRS for capturing the interspersed drug interactions and to characterize the interaction between the two drugs. METHODS: Left phrenic nerve-hemidiaphragms (Male Sprague-Dawley rats, 150-250 g) were mounted in Krebs solution. Supramaximal electrical stimulation (0.2 ms, rectangular) of 50 Hz for 1.9 s to the phrenic nerve evoked tetanic contractions that were measured with a force transducer. Each preparation was exposed to one of 4 vecuronium concentrations (0.0, 1.5, 2.5, and 3.0 microM), or one of 4 rocuronium concentrations (0.0, 3.0, 4.5, and 5.5 microM). Subsequently the adequate amount of rocuronium was added to a vecuronium bath and that of vecuronium was added to a rocuronium until an 80-90% increase in tetanic fade was achieved. We then fitted the modified KLGRS models to the above data, after which we selected the best model, based on 5 methods for determining goodness of fit. Using this method, we obtained the response surface, as well as contour plots for the response surface (i.e. isoboles), the polynomial function and the interaction index. RESULTS: The model with the constant relative potency ratio and 8 parameters was found to best describe the results, and this model reflected well the characteristics of the raw data. In addition, the two drugs showed a synergistic interaction in almost every area and an antagonistic one in a very narrow area. CONCLUSIONS: KLGRS was found to be a useful method of analyzing data describing interspersed drug interactions. The interaction between rocuronium and vecuronium was found to be synergistic.

Antiarrhythmic effect of ethyl acetate extract from Chrysanthemum Morifolium Ramat on rats / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effect of ethyl acetate extract from Chrysanthemum Morifolium Ramat (CME) on experimental arrhythmia induced by ischemia/reperfusion or aconitine in rats and to explore its underlying mechanisms.</p><p><b>METHODS</b>Arrhythmia model in intact rat was induced by aconitine (30 microg/kg body weight, i.v.). In isolated Langendorff perfused rat hearts, regional ischemia and reperfusion was induced by ligation and release of left anterior descending artery. The ventricular fibrillation threshold (VFT), effective refractory period (ERP), and diastolic excitation threshold (DET) in the isolated heart were measured. The action potentials of papillary muscle in rat right ventricle were recorded by conventional glass microelectrode technique.</p><p><b>RESULTS</b>Compared with control group CME significantly decreased the number and duration of ventricular tachycardia (VT); delayed the occurrence of ventricular premature beats (VPB) and VT induced by aconitine. Arrhythmia score of the CME group was lower than that in aconitine-treated group. CME markedly prolonged the ERP and increased the VFT in the isolated perfused rat hearts during ischemia and reperfusion. CME prolonged action potential duration at 50% and 90% repolarization of the right ventricular papillary muscles and decreased the maximal rate of rise of the action potential upstroke, but did not affect the resting potential, amplitude of action potential.</p><p><b>CONCLUSION</b>CME can reduce myocardial vulnerability and exerts its antiarrhythmic effects induced by aconitine or ischemia/reperfusion, which may be related to its prolongation of action potential duration and effective refractory period that enhance the electrophysiological stability of myocardiaium.</p>

Molecular mechanism of the changes in ventricular electrical remodeling caused by mechano-electrical feedback in rabbits with congestive heart failure / 生物医学工程学杂志

This study sought to explore the relationship between the change in ventricular electrical remodeling caused by mechano-electrical feedback and the expression of L-type Ca2+ -channel and/or sarcoplasmic reticulum Ca2+ -ATPase in the rabbits with congestive heart failure (CHF). 138 rabbits were divided into two groups (CHF and control). We measured the ventricular monophasic action potential duration (MAPD) and ventricular effective refractory period (VERP) during ventricular pacing at the stimulus frequency of 220/240/260 bpm in these rabbits. Rapid atrial pacing (260/min) was given for 30 minutes. The MAPD and VERP were measured again. Then ventricular fibrillation was induced by S1S2S3 program stimulation. We extracted the total RNA from the myocardium respectively and detected L-type Ca2+ -channel mRNA and sarcoplasmic reticulum Ca2+ -ATPase mRNA by use of Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). In group CHF, with the increasing of preload/afterload, L-type Ca2+ -channel mRNA was up regulated after rapid atrial pacing when compared with that in control groups (P < 0.05). There was no significant change in sarcoplasmic reticulum Ca2+ -ATPase mRNA after rapid atrial pacing when compared with controls (P > or = 0.05). The changes in MAPD90 and VERP were related with the extent of L-type Ca2+ -channel mRNA up regulation. But the changes in MAPD90 and VERP were not significantly related with the extent of sarcoplasmic reticulum Ca2+ -ATPase mRNA up regulation. These findings suggest that Mechano-Electrical Feedback could increase the regional changes of ventricular electrical remodeling in rabbits with CHF and so to predispose them to ventricular arrhythmia. The changes may be related with the up regulation of L-type Ca2+ -channel mRNA, but not with sarcoplasmic reticulum Ca2+ -ATPase mRNA.

Succinylcholine-induced phase II block and pharmacodynamics in rat diaphragm

BACKGROUND: Succinylcholine causes phase II block by a large dose or a prolonged exposure. There are rare data in a pharmacodynamics of phase II block. The purpose of this study was to investigate a concentration-response relationship, the occurrence and recovery of phase II block, and to clarify whether pretreatment of succinylcholine potentiates muscle relaxation caused by rocuronium. METHODS: Hemidiaphragm-phrenic nerve preparations were dissected from male Sprague-Dawley rats (150-250 g). Preparations were bathed in Krebs' solution, then maintained at 32oC, and saturated with a mixture of 95% O2 and 5% CO2. Isometric forces made with supramaximal stimulations (0.1 Hz, and 50 Hz for 1.9 s) to the phrenic nerve, were measured with a force transducer, before and after each treatment. Succinylcholine, 10, 20, 40, 60 and 80microM were cumulatively added to the bath. Succinylcholine 80microM (for 100 min) or succinylcholine 300microM (for 20 min) was washed out. After succinylcholine 300microM (for 20 min), or 0microM as pretreatment was washed out, rocuronium, 2, 4, 8, 12, 16, 20microM were cumulatively added to the bath. RESULTS: The potencies of single twitch, peak tetanic tension and tetanic fade for succinylcholine were 36.1, 26.0, 20.7microM. Irrespective of dose or exposure duration, the recovery of muscle relaxation caused by succinylcholine was almost complete around 20 min after succinylcholine was washed out. CONCLUSIONS: Tetanic fade occurred at a lower concentration of succinylcholine than single twitch. The recovery from phase II block was relatively rapid if the concentration of succinylcholine is sufficiently low.

Correlation between the refractory periods and threshold potentials and the spike programming in cortical neurons / 中国应用生理学杂志

<p><b>AIM</b>To investigate the intrinsic mechanisms underlying spike programming at pyramidal neurons and interneurons in layer II/III of sensorimotor cortex.</p><p><b>METHODS</b>Electrical signals at the cortical neurons were recorded in current clamp model with multi-clamp700B Amplifiers. Signals were inputted into pClamp and Origin for data acquisition and analyses.</p><p><b>RESULTS</b>Compared to pyramidal neurons, interneurons express the higher capacity of spikes and the more stability of spike programming, which are mechanistically caused by lower threshold potentials and shorter refractory periods.</p><p><b>CONCLUSION</b>The refractory periods and threshold potentials directly influence the programming of sequential spikes.</p>

Effects of acupuncture at Neiguan (PC 6) on function of sinoatrial node / 中国针灸

<p><b>OBJECTIVE</b>To observe effects of acupuncture at Neiguan (PC 6) on function of sinoatrial node, so as to provide experimental basis for clinical application of Neiguan (PC 6) to treatment of heart diseases.</p><p><b>METHODS</b>Fifty cases of heart diseases were randomly divided into 2 groups, a no-blocking group (n = 35) and a blocking group (n = 15). In the no-blocking group, sinoatrial node recovery time (SNRT), sinoatrial conduction time (SACT), sinoatrial node effective refractory period (SNERP) and heart rate (HR) were determined by using esophagus-left cardiac atrium regulating pulsation technique before and after acupuncture at Neiguan (PC 6); and in the blocking group, the vegetative nerve was blocked by intravenous injection of Propanolol and Atropine, and then SNRT, SACT, SNERP and intrinsic heart rate (IHR) were detected before and after acupuncture.</p><p><b>RESULTS</b>In the no-blocking group there were significant differences in SACT, SNERP and HR (all P < 0.05) and no significant difference in SNRT (P > 0.05) before and after treatment. In the blocking group, there were no significant differences in SNRT, SACT and SNERP and a significant difference in IHR before and after acupuncture (P < 0.05).</p><p><b>CONCLUSION</b>Acupuncture at Neiguan (PC 6) has a significant effect on function of sinoatrial node, and the mechanism is possibly related with the bidirectional regulative action of acupuncture at Neiguan (PC 6) on the autonomic nerve in the sinoatrial node.</p>

Modelo biomecánico de la generación de fuerza muscular en condiciones isométrica y tetánica / Biomechanical model of the generation in isometric muscle strength and tetanus

El objetivo de este trabajo consiste en elaborar un modelo estructural y matemático de la generación de fuerza del músculo esquelético en condiciones isométricas, y tetánica, que permita explicar las curvas Fuerza - tiempo (F - t) y Fuerza - longitud (F - l) obtenidas experimentalmente. Se propone un modelo macroscópico empaquetado que consta de un conjunto formado por un elemento contráctil, uno elástico y otro viscoso organizados en paralelo, y un elemento elástico en serie con el conjunto anterior. A este modelo se le aplican las leyes de Newton, para obtener la ecuación diferencial de movimiento del sistema. La solución de esta ecuación se está en un buen acuerdo con los resultados experimentales.

Brain areas activated after ejaculation in healthy young human subjects.

Brain mechanisms for the refractory period that characteristically follows ejaculation in animals and human are poorly understood. The possibility of active inhibition of brain areas being responsible for the post-ejaculatory inhibitory state has not been ruled out. Using Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) we have mapped brain areas in healthy young volunteers immediately after ejaculation. Functional imaging of the brain for 30 minutes beginning after three minutes of ejaculation induced by masturbation showed spatio-temporal activation in amygdala, temporal lobes and septal areas. The septal areas were observed to be active for a shorter duration than the amygdala and the temporal lobe. Thus the temporal sequence of involvement of the above neural structures may contribute to temporary inhibition of sexual arousal/penile erection during the post-ejaculatory refractory period in humans.