Splitting the P-Wave: Improved Evaluation of Left Atrial Substrate Modification after Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation

Atrial substrate modification after pulmonary vein isolation (PVI) of paroxysmal atrial fibrillation (pAF) can be assessed non-invasively by analyzing P-wave duration in the electrocardiogram (ECG). However, whether right (RA) and left atrium (LA) contribute equally to this phenomenon remains unknown. The present study splits fundamental P-wave features to investigate the different RA and LA contributions to P-wave duration. Recordings of 29 pAF patients undergoing first-ever PVI were acquired before and after PVI. P-wave features were calculated: P-wave duration (PWD), duration of the first (PWDon-peak) and second (PWDpeak-off) P-wave halves, estimating RA and LA conduction, respectively. P-wave onset (PWon-R) or offset (PWoff-R) to R-peak interval, measuring combined atrial/atrioventricular and single atrioventricular conduction, respectively. Heart-rate fluctuation was corrected by scaling. Pre- and post-PVI results were compared with Mann–Whitney U-test. PWD was correlated with the remaining features. Only PWD (non-scaling: Δ=−9.84%, p=0.0085, scaling: Δ=−17.96%, p=0.0442) and PWDpeak-off (non-scaling: Δ=−22.03%, p=0.0250, scaling: Δ=−27.77%, p=0.0268) were decreased. Correlation of all features with PWD was significant before/after PVI (p<0.0001), showing the highest value between PWD and PWon-R (ρmax=0.855). PWD correlated more with PWDon-peak (ρ= 0.540–0.805) than PWDpeak-off (ρ= 0.419–0.710). PWD shortening after PVI of pAF stems mainly from the second half of the P-wave. Therefore, noninvasive estimation of LA conduction time is critical for the study of atrial substrate modification after PVI and should be addressed by splitting the P-wave in order to achieve improved estimations.

Preserved central cholinergic functioning to transcranial magnetic stimulation in de novo patients with celiac disease

Background Celiac disease (CD) is now viewed as a systemic disease with multifaceted clinical manifestations. Among the extra-intestinal features, neurological and neuropsychiatric symptoms are still a diagnostic challenge, since they can precede or follow the diagnosis of CD. In particular, it is well known that some adults with CD may complain of cognitive symptoms, that improve when the gluten-free diet (GFD) is started, although they may re-appear after incidental gluten intake. Among the neurophysiological techniques, motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) can non-invasively probe in vivo the excitation state of cortical areas and cortico-spinal conductivity, being also able to unveil preclinical impairment in several neurological and psychiatric disorders, as well as in some systemic diseases affecting the central nervous system (CNS), such as CD. We previously demonstrated an intracortical disinhibition and hyperfacilitation of MEP responses to TMS in newly diagnosed patients. However, no data are available on the central cholinergic functioning indexed by specific TMS measures, such as the short-latency afferent inhibition (SAI), which might represent the neurophysiological correlate of cognitive changes in CD patients, also at the preclinical level. Methods Cognitive and depressive symptoms were screened by means of the Montreal Cognitive Assessment (MoCA) and the 17-item Hamilton Depression Rating Scale (HDRS), respectively, in 15 consecutive de novo CD patients and 15 healthy controls. All patients were on normal diet at the time of the enrolment. Brain computed tomography (CT) was performed in all patients. SAI, recorded at two interstimulus intervals (2 and 8 ms), was assessed as the percentage amplitude ratio between the conditioned and the unconditioned MEP response. Resting motor threshold, MEP amplitude and latency, and central motor conduction time were also measured. Results The two groups were comparable for age, sex, anthropometric features, and educational level. Brain CT ruled out intracranial calcifications and clear radiological abnormalities in all patients. Scores at MoCA and HDRS were significantly worse in patients than in controls. The comparison of TMS data between the two groups revealed no statistically significant difference for all measures, including SAI at both interstimulus intervals. Conclusions Central cholinergic functioning explored by the SAI of the motor cortex resulted to be not affected in these de novo CD patients compared to age-matched healthy controls. Although the statistically significant difference in MoCA, an overt cognitive impairment was not clinically evident in CD patients. Coherently, to date, no study based on TMS or other diagnostic techniques has shown any involvement of the central acetylcholine or the cholinergic fibers within the CNS in CD. This finding might add support to the vascular inflammation hypothesis underlying the so-called “gluten encephalopathy”, which seems to be due to an aetiology different from that of the cholinergic dysfunction. Longitudinal studies correlating clinical, TMS, and neuroimaging data, both before and after GFD, are needed.

Evaluatıon Of The Effect Of Pulmonary Veın Isolatıon Treatment With Left Atrıal Catheter Ablatıon Method On Atrıal Conductıon Tımes In Patıents With Paroxysmal Atrıal Fıbrıllatıon

Purpose:Atrial fibrillation(AF) causes structural, electrical, and cellular remodeling in the atrium. Evaluation of intra- and interatrial conduction time, which is measured by tissue doppler echocardiography, indicates structural and electrical remodeling in the atrium. The aim of this study was to evaluate the effect of pulmonary vein isolation applied with RF ablation therapy on intra- and interatrial conduction time and to investigate the structural and electrically remodeling after treatment. Methods:Fifty-two patients with symptomatic PAF despite at least one antiarrhythmic drug and without structural heart disease were included in the study. Two patients were excluded because of complications developed during and after the operation. Fifty patients (28 female; mean age: 51.68 ± 11.731; mean left atrial diameter: 36.79 ± 4.318) who underwent CARTO® 3D pulmonary vein isolation applied with the RF ablation system were followed-up. Intra- and the inter-atrial electromechanical delay was measured in all patients by tissue doppler echocardiography before and three months after RF ablation. Results:All intra- and interatrial conduction times were significantly decreased 3 months after RF ablation procedure(PA lateral p = 0.022; PA septum p = 0.002; PA tricuspid p = 0.019, interatrial conduction delay p= 0,012, intra-atrial conduction delay p = 0.029). Conclusion:The results of our study suggest that providing stable sinus rhythm by the elimination of the AF triggering mechanisms with RF ablation of pulmonary vein isolation may slow down,stop or even improve structural remodeling at substrate level secondary to AF even in patients who did not yet develop atrial fibrosis and permanent structural changes.

NAIAD-2020: Characteristics of Motor Evoked Potentials After 3-Day Exposure to Dry Immersion in Women

As female astronauts participate in space flight more and more frequently, there is a demand for research on how the female body adapts to the microgravity environment. In particular, there is very little research on how the neuromuscular system reacts to gravitational unloading in women. We aimed to estimate changes in motor evoked potentials (MEPs) in the lower leg muscles in women after 3-day exposure to Dry Immersion (DI), which is one of the most widely used ground models of microgravity. Six healthy female volunteers (mean age 30.17 ± 5.5 years) with a natural menstrual cycle participated in this experiment. MEPs were recorded from the gastrocnemius and soleus muscles twice before DI, on the day of DI completion, and 3 days after DI, during the recovery period. To evoke motor responses, transcranial and trans-spinal magnetic stimulation was applied. We showed that changes in MEP characteristics after DI exposure were different depending on the stimulation site, but were similar for both muscles. For trans-spinal stimulation, MEP thresholds decreased compared to baseline values, and amplitudes, on the contrary, increased, resembling the phenomenon of hypogravitational hyperreflexia. This finding is in line with data observed in other experiments on both male and female participants. MEPs to transcranial stimulation had an opposing dynamic, which may have resulted from the small group size and large inter-subject variability, or from hormonal fluctuations during the menstrual cycle. Central motor conduction time remained unchanged, suggesting that pyramidal tract conductibility was not affected by DI exposure. More research is needed to explore the underlying mechanisms.

216 The ‘inflammatory perfect storm’: a case of COVID-19 pneumonia complicated by pulmonary embolism

Aims The inflammatory ‘cytokine storm’ that distinguishes COVID-19 pneumonia is associated with a state of systemic hypercoagulability, which leads to thrombotic complications on the venous, arterial, and microvascular side. Indeed, in patients with COVID-19, systemic inflammation, coagulation activation, hypoxemia, and immobilization expose a high risk of pulmonary embolism, which significantly worsens the prognosis of these patients. Methods and results In this report, we discuss the case of a 71-year-old female, with no prior medical history, admitted to the emergency department for syncope, dyspnoea, and fever started 48 h earlier. At presentation, ear temperature was 37 °C, oxygen saturation was 96% on oxygen therapy (6 l/min), the patient appeared hypertensive (160/80 mmHg) and tachycardic (114 b.p.m.). Laboratory tests revealed normal white blood cells count (10 000/μl) and increased C reactive protein (5.60 mg/dl), troponin I (0.417 ng/ml), and d-dimer levels (15743 ng/ml). Electrocardiogram showed sinus tachycardia at HR of 120/min, normal atrioventricular conduction time, new onset right bundle branch block, and inverted T waves on DIII. Considering the symptoms, CTPA was performed, revealing massive acute bilateral pulmonary embolism with peripheral ground glass opacities. Those findings were suggestive of COVID-19 pneumonia. Indeed, the patient was positive for SARS-CoV-2 infection, and a diagnosis of COVID-19 pneumonia complicated by pulmonary embolism was made. Treatments included oxygen, subcutaneous low molecular weight heparin (LWMH), and corticosteroids have been administrated according to current international guidelines. Since no haemodynamic instability was observed during hospitalization the patient was discharged on Warfarin therapy for 6 months. Conclusions In COVID-19 patients treated in a hospital the incidence of pulmonary embolism (PE) is very high. Patients with COVID-19 infection have respiratory symptoms, which often may not be distinguishable from pulmonary embolism symptoms. So, unexpected respiratory worsening, signs of right ventricular dysfunction on transthoracic echocardiogram, and ECG changes should lead to suspicion of the co-presence of pulmonary embolism. This case report shows how COVID-19 infection can be strongly associated with thrombotic complications. For this reason, the guidelines recommend anticoagulation at standard prophylactic doses in all patients admitted with COVID-19 infection.

Evoked potentials as biomarkers of hereditary spastic paraplegias: A case-control study

Introduction The Hereditary Spastic Paraplegias (HSP) are a group of genetic diseases that lead to slow deterioration of locomotion. Clinical scales seem to have low sensitivity in detecting disease progression, making the search for additional biomarkers a paramount task. This study aims to evaluate the role of evoked potentials (EPs) as disease biomarkers of HSPs. Methods A single center cross-sectional case-control study was performed, in which 18 individuals with genetic diagnosis of HSP and 21 healthy controls were evaluated. Motor evoked potentials (MEP) obtained with transcranial magnetic stimulation and somatosensory evoked potentials (SSEP) were performed in lower (LL) and upper limbs (UL). Results Central motor conduction time in lower limbs (CMCT-LL) was prolonged in HSP subjects, with marked reductions in MEP-LL amplitudes when compared to the control group (p<0.001 for both comparisons). CMCT-UL was 3.59ms (95% CI: 0.73 to 6.46; p = 0.015) prolonged and MEP-UL amplitudes were reduced (p = 0.008) in the HSP group. SSEP-LL latencies were prolonged in HSP subjects when compared to controls (p<0.001), with no statistically significant differences for upper limbs (p = 0.147). SSEP-UL and SSEP-LL latencies presented moderate to strong correlations with age at onset (Rho = 0.613, p = 0.012) and disease duration (Rho = 0.835, p<0.001), respectively. Similar results were obtained for the SPG4 subgroups of patients. Conclusion Motor and somatosensory evoked potentials can adequately differentiate HSP individuals from controls. MEP were severely affected in HSP subjects and SSEP-LL latencies were prolonged, with longer latencies being related to more severe disease. Future longitudinal studies should address if SSEP is a sensitive disease progression biomarker for HSP.

The role of neurophysiological assessments during the combined treatment of patients with malignant brain tumors

Introduction. Dynamic monitoring and evaluation of the results of therapy of patients with malignant brain diseases is a complex and urgent problem in modern medicine. The aim of the study was to assess the reliability of the transcranial magnetic stimulation technique as a tool for neurophysiological monitoring in patients with malignant brain tumors. Material and methods. Two groups of patients were formed: adults with large focal solitary lesions of the central nervous system (glioma) (n=20), who underwent radiotherapy, and a control comparison group (n=16). All patients underwent diagnostic transcranial magnetic stimulation before and after treatment. Results. In the main group the application of transcranial magnetic stimulation in dynamics allowed to reveal reliable improvement of conduction along the central motor pathways (increase in amplitude of the evoked motor response). The obtained data of neurophysiological examination correlated with clinical improvement in the patient group. Discussion. Some parameters of the motor evoked response (MEP) changed reliably, as after the radiation treatment performed. Obtained changes (amplitude of MEP and, especially, its threshold) to the greatest extent reflect functional state of cortical motoneurons, as well as their anatomical preservation in case of organic changes. Before therapy in all cases there was a reliable tendency to a smaller amplitude and a higher threshold of cortical MEPs, which reflects a decrease in the functional activity of motor cortex neurons; a slower central motor conduction time also draws attention. These changes had a universal character and were registered in all patients. Conclusion. Diagnostic transcranial magnetic stimulation, taking into account age limitations inherent to it as a technique, is a valuable additional neurophysiological technique. It is safe, inexpensive and does not require expensive consumables, and is applicable to a wide range of diseases.

Comparison of The Electrophysiological Characteristics of Tight Filum Terminale And Tethered Cord Syndrome

This study aims to characterize tight filum terminale (TFT) in motor evoked potential (MEP) testing by comparing TFT patients with both tether cord syndrome (TCS) patients and healthy subjects. Fifty TFT patients, 18 TCS patients, and 35 healthy volunteers participated in this study. We recorded MEPs following transcranial magnetic stimulation from the bilateral abductor hallucis muscles as well as compound muscle action potentials and F-waves evoked by electrical stimulation of the tibial nerve from the bilateral abductor pollicis brevis muscles. The peripheral conduction time (PCT) was calculated from the latency of the compound action potential and F-wave. Furthermore, the central motor conduction time (CMCT) was calculated by subtracting PCT from MEP latency. TFT and TCS patients had a significantly longer MEP latency than healthy subjects. PCT in TFT patients were significantly longer than those in TCS patients or healthy subjects. Using the cut-off values for PCT, we were able to diagnose patients with TFT patients with a sensitivity of 72.0% and a specificity of 91.4%. Prolonged PCT in the MEP test may be a useful indicator for TFT and suggests that MEP may be used as an adjunct diagnostic tool for TFT.

Some issues of the operation of plasma opening switches

The paper analyzes some processes in a plasma opening switch with a conduction time of ~ 100 ns. Relations are derived for assessing the evolution of the ion current to its space charge-limited state and for estimating its maximum possible density. It is shown that the ion current density reaches its extremum before electron magnetization. Estimates for the electromagnetic energy delivered to the switch are also presented demonstrating that this energy is spent equally for creating a magnetic field in the plasma volume and for its ohmic heating.