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BACKGROUND AND AIMS: Charcot-Marie-Tooth (CMT) is a heterogeneous group of genetic neuropathies and is typically characterized by distal muscle weakness, sensory loss, pes cavus and areflexia. Herein we describe a case of CMT2CC presenting with proximal muscle weakness and equivocal electrophysiological features, that was misdiagnosed as chronic inflammatory demyelinating polyneuropathy (CIDP). CASE REPORT: A 30-year-old woman complained of proximal muscle weakness with difficulty climbing stairs. Neurological examination showed weakness in lower limb (LL) muscles, that was marked proximally and mild distally, and absence of deep tendon reflexes in the ankles. Nerve conduction studies (NCS) showed sensory-motor neuropathy with non-uniform NC velocity and a partial conduction block (CBs) in peroneal nerve and tibial nerves. Thus, a diagnosis of CIDP was entertained and the patient underwent ineffective treatment with intravenous immunoglobulins. At electrophysiological revaluation CB in peroneal nerve was undetectable as also distal CMAP had decreased whereas the CBs persisted in tibial nerves. Hypothesizing a hereditary neuropathy, we examined the proband's son, who presented mild weakness of distal and proximal muscles at lower limbs. Neurophysiological investigation showed findings consistent with an intermediate-axonal electrophysiological pattern. A targeted-NGS including 136 CMT genes showed the heterozygous frameshift mutation (c.3057dupG; p.K1020fs*43) in the NEFH gene, coding for the neurofilament heavy chain and causing CMT2CC. INTERPRETATION: Diagnosis of a genetic neuropathy may be challenging when clinical features are atypical and/or electrophysiological features are misleading. The most common misdiagnosis is CIDP. Our report suggests that also CMT2CC patients with proximal muscle weakness and equivocal electrophysiological features might be misdiagnosed as CIDP.

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A 26-year-old woman presented with a seven-month history of weakness in her left upper limb, progressing to difficulty lifting her arms within a few weeks. Her symptoms progressed with fluctuations. For the past three months, she has been unable to stand due to weakness in her proximal lower limbs. Nerve conduction studies did not show any definite conduction block or abnormal sensory conduction, but motor conduction studies showed a slight prolongation of the terminal latency and a decrease in the frequency of the F-wave. A magnetic fatigue test indicated a proximal conduction block. Her symptoms were rapidly resolved with intravenous immunoglobulin treatment, leading to a diagnosis of chronic immune-mediated neuropathy, met both criteria for multifocal motor neuropathy (MMN) and motor chronic inflammatory demyelinating polyneuropathy (CIDP). Our case highlights the utility of the magnetic fatigue test in detecting conduction blocks and its role in differentiating between MMN and motor CIDP.

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Seldom are reports of phase 4 block or bradycardia-dependent conduction block in atrial tissue found in the literature. Here, we describe the case of a patient with sick sinus syndrome with Torsade de Pointes who, following the implantation of a double-chamber implantable cardioverter defibrillator, developed intra-atrial bradycardia-dependent conduction block. The patient's optimal pacing parameters were achieved by raising the rate.

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A 23-year-old male with a history of ventricular pre-excitation and atrial flutter presented for evaluation after recurrent syncope. The possible mechanism of syncope erroneously attributed to pre-excited atrial flutter with fast heart rates in the first hospitalization. The patient was found to have advanced heart block and PRKAG2 genetic mutation in the second hospitalization. The genetic findings and clinical features are consistent with PRKAG2 syndrome (PS). PS is a rare, autosomal dominant inherited disease, characterized by ventricular pre-excitation, supraventricular tachycardia, and cardiac hypertrophy. It is frequently followed by atrial-fibrillation-induced ventricular fibrillation and advanced heart blocks. An accurate differential diagnosis of syncope is important because of the different arrhythmic features and clinical course of PS.

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Objective: This study aimed to explore the impact of a combination of hyperuricemia (HUA) and excessive high-sensitivity C-reactive protein (hs-CRP) levels on the likelihood of developing cardiac conduction block (CCB). Additionally, it sought to assess whether the influence of uric acid (UA) on CCB is mediated by hs-CRP. Methods: A prospective study was executed utilizing data from the Kailuan cohort, including 81,896 individuals initially free from CCB. The participants were categorized into four groups depending on the existence of HUA and low-grade inflammation (hs-CRP>3 mg/L). Cox regression analysis was employed to ascertain hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of incident CCB. A mediation analysis was performed to determine if hs-CRP functioned as a mediator in the connection between UA levels and the incidence of CCB. Results: During a median observation period of 11.8 years, we identified 3160 cases of newly occurring CCB. Compared with the low UA/low CRP group, the combination of HUA and low-grade inflammation elevated the CCB risks (HR:1.56, 95% CI:1.22-1.99), atrioventricular block (AVB) (HR:1.88, 95% CI:1.27-2.77), and right bundle branch block (HR:1.47, 95% CI:1.02-2.12), respectively. Mediation analysis revealed that in the HUA group, compared with the non-HUA group, the risk of CCB elevated by 14.0%, with 10.3% of the increase mediated through hs-CRP. Conclusion: HUA combined with elevated hs-CRP increased the risk of CCB, especially AVB. The connection between UA and the CCB risk was partly mediated by hs-CRP.

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The following case series presents three different pediatric patients with SCN5A-related disease. In addition, family members are presented to demonstrate the variable penetrance that is commonly seen. Identifying features of this disease is important, because even in the very young, SCN5A disorders can cause lethal arrhythmias and sudden death.

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BACKGROUND: Intravenous immunoglobulin (IVIg) and plasmapheresis (PLEX) are recommended in moderate to severe Guillain-Barré Syndrome (GBS), but there is paucity of studies evaluating its effect on nerve conduction studies (NCS). We report the effect of IVIg and PLEX on the NCS parameters and clinical outcomes compared to natural course (NC) of GBS patients. METHOD: Moderate to severe GBS patients were included based on clinical, cerebrospinal fluid, and NCS finding. Six motor and sensory nerves were evaluated at admission, one month and 3 months, and NCS subtyping was done. Axonal and demyelination burden in motor nerves and early reversible conduction block (ERCB) were noted. Patients receiving IVIg, PLEX or on NC were noted. Outcome was defined at 3 months into complete, partial and poor using a 0-6 GBS Disability Scale (GBSDS). RESULT: Seventy-two patients were included, whose median age was 36 years and 22(30.6 %) were females. 44 patients received IVIg, 9 PLEX and 19 were in NC, and they had comparable peak disability. AIDP was the dominant subtype at admission (58.3 %), which remained so at 3 months (50 %). The shift of subtypes was the highest from the equivocal group followed by AMAN and the least from AIDP. IVIg and PLEX group had more reduction in axonal burden and had ERCB compared to NC. 33(44 %) patients had complete recovery, and 40(55.5 %) patients had concordance in clinical and neurophysiological outcome. CONCLUSION: Transition of GBS subtype may occur at follow-up from all the subtypes, the highest from the equivocal and the lowest from the AIDP group. IVIg/PLEX treatment may help in reducing conduction block and axonal burden.

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Electrodiagnostic (EDX) testing plays an important role in confirming a mononeuropathy, localizing the site of nerve injury, defining the pathophysiology, and assessing the severity and prognosis. The combination of nerve conduction studies (NCS) and needle electromyography findings provides the necessary information to fully assess a nerve. The pattern of NCS abnormalities reflects the underlying pathophysiology, with focal slowing or conduction block in neuropraxic injuries and reduced amplitudes in axonotmetic injuries. Needle electromyography findings, including spontaneous activity and voluntary motor unit potential changes, complement the NCS findings and further characterize chronicity and degree of axon loss and reinnervation. EDX is used as an objective marker to follow the progression of a mononeuropathy over time.

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BACKGROUND: High-resolution mapping offers superior accuracy in delineating conduction features; however, certain characteristics are still linked to elevated recurrence rates of atrial tachycardia (AT), suggesting the influence of additional mechanisms. This study systematically assessed the substrate of functional conduction block (FCB) regions in relation to the mechanisms of multiple ATs. METHODS: In this study, the Carto system facilitated the mapping of ATs in 13 patients undergoing ablation, each presenting with more than two AT variants. FCB regions were marked and further analyzed. RESULTS: A total of 33 sustained ATs were mapped across the patient cohort. FCB regions showed convertibility in 7 of 13 patients (54%). Three kinds of presentations can be summarized by the FCB region: Firstly, the FCB region could act as the main obstacle sustaining the localized reentrant pathway, for which rounding obviously has a direct correlation with the mechanism of the AT (27%). Secondly, the FCB regions could act as obstacle lines to reorganize the propagation of the reentry in localized AT and macroreentrant AT (55%). Lastly, the FCB region could act as a bystander and may not be related to the mechanism of the ATs (18%). The potentials in FCB regions mostly performed low voltages or fragmented potentials (FPs) in the ATs which they did not perform the conduction block (90%). CONCLUSION: In multiple ATs, FCB regions may not be uncommon. The participation of FCB regions in the mechanism of ATs showed three different kinds of performance. The dynamic nature of this substrate may provide insight into the reasons for the high recurrence of related ATs.

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Nerve conduction studies are usually the first diagnostic step in peripheral nerve disorders and their results are the basis for planning further investigations. However, there are some commonplaces in the interpretation of electrodiagnostic findings in peripheral neuropathies that, although useful in the everyday practice, may be misleading: (1) conduction block and abnormal temporal dispersion are distinctive features of acquired demyelinating disorders; (2) hereditary neuropathies are characterized by uniform slowing of conduction velocity; (3) axonal neuropathies are simply diagnosed by reduced amplitude of motor and sensory nerve action potentials with normal or slightly slow conduction velocity. In this review, we reappraise the occurrence of uniform and non-uniform conduction velocity slowing, conduction block and temporal dispersion in demyelinating, dysmyelinating and axonal neuropathies attempting, with a translational approach, a correlation between electrophysiological and pathological features as derived from sensory nerve biopsy in patients and animal models. Additionally, we provide some hints to navigate in this complex field.

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BACKGROUND: Despite the advancements in heart failure(HF) research, the early diagnosis of HF continues to be a challenging issue in clinical practice. This study aims to investigate the genes related to myocardial fibrosis and conduction block, with the goal of developing a diagnostic model for early treatment of HF in patients. METHOD: The gene expression profiles of GSE57345, GSE16499, and GSE9128 were obtained from the Gene Expression Omnibus (GEO) database. After merging the expression profile data and adjusting for batch effects, differentially expressed genes (DEGs) associated with conduction block and myocardial fibrosis were identified. Gene Ontology (GO) resources, Kyoto Encyclopedia of Genes and Genomes (KEGG) resources, and gene set enrichment analysis (GSEA) were utilized for functional enrichment analysis. A protein-protein interaction network (PPI) was constructed using a string database. Potential key genes were selected based on the bioinformatics information mentioned above. SVM and LASSO were employed to identify hub genes and construct the module associated with HF. The mRNA levels of TAC mice and external datasets (GSE141910 and GSE59867) are utilized for validating the diagnostic model. Additionally, the study explores the relationship between the diagnostic model and immune cell infiltration. RESULTS: A total of 395 genes exhibiting differential expression were identified. Functional enrichment analysis revealed that these specific genes primarily participate in biological processes and pathways associated with the constituents of the extracellular matrix (ECM), immune system processes, and inflammatory responses. We identified a diagnostic model consisting of 16 hub genes, and its predictive performance was validated using external data sets and a transverse aortic coarctation (TAC) mouse model. In addition, we observed significant differences in mRNA expression of 7 genes in the TAC mouse model. Interestingly, our study also unveiled a correlation between these model genes and immune cell infiltration. CONCLUSIONS: We identified sixteen key genes associated with myocardial fibrosis and conduction block, as well as diagnostic models for heart failure. Our findings have significant implications for the intensive management of individuals with potential genetic variants associated with heart failure, especially in the context of advancing cell-targeted therapy for myocardial fibrosis.

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BACKGROUND: The association of longitudinal uric acid (UA) changes with cardiac conduction block risk is unclear. We aimed to identify the trajectories of UA and explore its association with cardiac conduction block. METHODS: A total of 67,095 participants with a mean age of 53.12 years were included from the Kailuan cohort in Tangshan, China, who were free of cardiac conduction block and with repeated measurements of UA from 2006 to 2012. UA trajectories during 2006 to 2012 were identified by group-based trajectory modeling. Cox proportional hazard regression models were used to assess the association of UA trajectories with cardiac conduction block. RESULTS: We categorized three observed discrete trajectories of UA during 2006-2012 period: low-stable, moderate-stable, and high-stable. Over a median follow-up of 6.19 years, we identified 1405 (2.09%) incident cardiac conduction block. Compared to those in the low-stable trajectory, the adjusted hazard ratios (HRs) (95% confidence interval [CI]) of cardiac conduction block in the moderate-stable and high-stable trajectory were 1.30 (1.16-1.47) and 1.86 (1.56-2.22), and HRs of atrioventricular block were 1.39 (1.12-1.72) and 2.90 (2.19-3.83), and HRs of bundle branch blocks were 1.27 (1.10-1.47) and 1.43 (1.13-1.79). Notably, although the average UA level in the moderate-stable UA trajectory group is within the normal range, the risk of cardiac conduction block has increased. CONCLUSIONS: The moderate-stable and high-stable trajectories are associated with increased risk for new-onset cardiac conduction block. Monitoring UA trajectories may assist in identifying subpopulations at higher risk for cardiac conduction block.

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(1) Background: Structural remodeling plays an important role in the pathophysiology of atrial fibrillation (AF). It is likely that structural remodeling occurs transmurally, giving rise to electrical endo-epicardial asynchrony (EEA). Recent studies have suggested that areas of EEA may be suitable targets for ablation therapy of AF. We hypothesized that the degree of EEA is more pronounced in areas of transmural conduction block (T-CB) than single-sided CB (SS-CB). This study examined the degree to which SS-CB and T-CB enhance EEA and which specific unipolar potential morphology parameters are predictive for SS-CB or T-CB. (2) Methods: Simultaneous endo-epicardial mapping in the human right atrium was performed in 86 patients. Potential morphology parameters included unipolar potential voltages, low-voltage areas, potential complexity (long double and fractionated potentials: LDPs and FPs), and the duration of fractionation. (3) Results: EEA was mostly affected by the presence of T-CB areas. Lower potential voltages and more LDPs and FPs were observed in T-CB areas compared to SS-CB areas. (4) Conclusion: Areas of T-CB could be most accurately predicted by combining epicardial unipolar potential morphology parameters, including voltages, fractionation, and fractionation duration (AUC = 0.91). If transmural areas of CB indeed play a pivotal role in the pathophysiology of AF, they could theoretically be used as target sites for ablation.

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The use of peripheral regional anaesthesia continues to increase, yet the evidence supporting its use and impact on relevant outcomes often lacks scientific rigour, especially when considering the use of specific blocks for a particular surgical indication. In this narrative review, we consider the relevant literature in a 10-yr period from 2013. We performed a literature search (MEDLINE and EMBASE) for articles reporting randomised controlled trials and other comparative trials of peripheral regional anaesthetic blocks vs systemic analgesia in adult patients undergoing surgery. We evaluated measures of effective treatment and complications. A total of 128 studies met our inclusion criteria. There remains variability in the technical conduct of blocks and the outcomes used to evaluate them. There is a considerable body of evidence to support the use of interscalene blocks for shoulder surgery. Saphenous nerve (motor-sparing) blocks provide satisfactory analgesia after knee surgery and are preferred to femoral nerve blocks which are associated with falls when patients are mobilised early as part of enhanced recovery programmes. There are additional surgical indications where the efficacy of cervical plexus, intercostal nerve, and ilioinguinal/iliohypogastric nerve blocks have been demonstrated. In the past 10 yr, there has been a consolidation of the evidence indicating benefit of peripheral nerve blocks for specific indications. There remains great scope for rigorous, multicentre, randomised controlled trials of many peripheral nerve blocks. These would benefit from an agreed set of patient-centred outcomes.

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BACKGROUND: Despite the suggestion that direct compression by granuloma and ischemia resulting from vasculitis can cause nerve fiber damage, the mechanisms underlying sarcoid neuropathy have not yet been fully clarified. METHODS: We examined the clinicopathological features of sarcoid neuropathy by focusing on electrophysiological and histopathological findings of sural nerve biopsy specimens. We included 18 patients with sarcoid neuropathy who had non-caseating epithelioid cell granuloma in their sural nerve biopsy specimens. RESULTS: Although electrophysiological findings suggestive of axonal neuropathy were observed, particularly in the lower limbs, all but three patients showed ≥1 abnormalities in nerve conduction velocity or distal motor latency. Additionally, a conduction block was observed in 11 of the 16 patients for whom waveforms were assessed; five of them fulfilled motor nerve conduction criteria strongly supportive of demyelination as defined in the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guideline for chronic inflammatory demyelinating polyneuropathy (CIDP). In most patients, sural nerve biopsy specimens revealed a mild to moderate degree of myelinated fiber loss. Fibrinoid necrosis was observed in one patient, and electron microscopy analysis revealed demyelinated axons close to granulomas in six patients. CONCLUSIONS: Patients with sarcoid neuropathy may meet the EAN/PNS electrophysiological criteria for CIDP due to the frequent presence of conduction blocks. Based on our results, in addition to the ischemic damage resulting from granulomatous inflammation, demyelination may play an important role in the mechanism underlying sarcoid neuropathy.

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BACKGROUND: Although bundle branch block and atrioventricular block are recognized to be association with cardiovascular disease (CVD) and mortality, the relationship between cardiac conduction block (CCB) and both CVD and all-cause mortality has yet to be explored. AIMS: To explore the relationship between CCB and CVD and all-cause mortality. METHODS AND RESULTS: We included 145,805 subjects (mean age 49.7 years, 81.2% males) from the kailuan study. CCB was diagnosed through a 12­lead electrocardiograph (ECG). Mortality and CVD events were ascertained through multiple sources, including a municipal social insurance institution, hospital records, death certificates, and regular active follow-ups. After a mean follow-up of 12.5 years, 18,301 cases developed all-cause mortality. After excluding 4443 subjects with CVD presence at baseline, 13,208 cases of CVD occurred among the 141,362 study subjects during follow-up. Compared with non-CCB group, the cumulative incidence of CVD and all-cause mortality for CCB group was 18.38% VS 12.14% and 33.45% VS 14.18%, respectively. The multivariable-adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) with CCB group were 1.25(1.17-1.34) for CVD, and 1.31(1.25-1.38) for all-cause mortality. Additionally, there were generally stronger associations for CCB with all-cause mortality and CVD in younger participants compared with their older counterparts (Ps-interaction <0.001). CONCLUSION: CCB can increase the risk of CVD and all-cause mortality in the general population. Our findings highlight the importance of strategies for preventing CCB to reduce the risk of CVD and mortality.

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OBJECTIVE: To evaluate the effect of calcification distributional density in different regions of aortic-valvular complex (AVC) on postoperative new-onset conduction block (CB) following transcatheter aortic valve replacement (TAVR) using self-expandable valves (SEV) made in China. METHODS: From January, 2016 to December, 2022, 73 patients with severe aortic valve stenosis received Venus-A prosthetic valve replacement using SEV made in China, and postoperative new-onset CB occurred in 18 (24.7%) of the patients. The baseline data, imaging and intervention- related data were compared were between the patients with CB and those without CB. Univariate and multivariate logistic regression analysis was used for investigating the independent risk factors for new- onset CB after TAVR, and the predictive performance of these risk factors was evaluated using receiver operating characteristic (ROC) curve and DeLong test. RESULTS: Compared with those with CB, the patients experiencing postoperative new-onset CB had a greater implantation depth (6.77±2.45 mm vs 5.11±3.28 mm, P=0.027), a smaller difference between the membranous septum length and the implantation depth (MSID) (0.68±3.49 mm vs 2.82±3.88 mm, P= 0.036), and a higher calcification distributional density of the left coronary sinus (LCS) in the device landing zone (DLZ) (P= 0.026). Multivariate logistic analysis revealed that DLZ-LCS calcification distributional density and MSID were independent risk (protective) factors for new-onset CB following TAVR. ROC curve analysis showed that the AUC of MSID and DLZ-LCS calcification distributional density was 0.775 and 0.716, respectively, and their combination had had a significantly higher AUC of 0.890 (P=0.041 and 0.027, respectively). CONCLUSION: The DLZ-LCS calcification distributional density is an independent risk factor for new-onset CB following TAVR using SEV. The conduction complications following TAVR can be effectively predicted using this calcification indicator combined with MSID.

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Purpose: Inflammation plays a critical role in the development of cardiac conduction block (CCB), which is associated with an increased risk of morbidity and mortality. The monocyte-lymphocyte ratio (MLR) acts as a novel inflammatory marker; however, its association with CCB has not yet been studied. This study aimed to investigate the association between MLR and CCB risk. Patients and Methods: In total, 82,472 CCB-free participants were identified from the Kailuan study. MLR was calculated using the monocyte count/lymphocyte count. The participants were stratified based on quartiles of MLR levels. Incident CCB and its subtypes were ascertained from electrocardiograms at biennial follow-up visits. The Cox proportional hazards model and restricted cubic spline analysis were used to investigate the association between MLR with CCB and its subtypes. Results: During a median follow-up of 10.4 years, 3222 incident CCB cases were observed. A U-shaped association was observed between MLR and CCB risk (Pnonlinearity <0.05). After multivariate adjustment, individuals in the highest MLR quartile had a hazard ratio (HR) of 1.212 (95% CI: 1.097-1.340; Q4 vs Q2), while those in the lowest MLR quartile had an HR of 1.106 (95% CI: 1.000-1.224; Q1 vs Q2). Sensitivity and subgroup analyses yielded consistent results. The U-shaped association persisted for atrioventricular block (AVB) in subtype analyses. Conclusion: MLR was significantly associated with an increased risk of new-onset CCB. Assessing MLR may have clinical relevance for predicting CCB risk, providing valuable insights for preventive strategies and patient management. Pre-Registered Clinical Trial Number: The pre-registered clinical trial number is ChiCTR-TNC-11001489.

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Introduction: Permanent pacemaker implantation (PPI) is a known complication in patients with aortic stenosis following transcatheter aortic valve implantation (TAVI). However, there is limited research on TAVI for pure aortic regurgitation (PAR), and more investigation is needed to determine the occurrence of postoperative cardiac conduction block and the need for PPI in this population. Therefore, this retrospective analysis aimed to evaluate the incidence of cardiac conduction block and the necessity of PPI after TAVI in patients with different types of aortic valve disease, including pure aortic stenosis (PAS), aortic stenosis with regurgitation (ASR), and PAR. Methods: Clinical data of 100 patients who TAVI were analyzed retrospectively. The incidence of conduction block was assessed, and clinical factors were examined to predict the necessity of PPI. Results: Cardiac conduction block was found to be a common complication following TAVI, particularly in patients with PAR. PAR was identified as an independent risk factor for requiring PPI. Additionally, first-degree atrioventricular block emerged as a sensitive predictor for PPI in patients with PAR. Discussion: These findings provide valuable insights into the safety and effectiveness of TAVI, which can help enhance patient management and reduce complications.