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neuECG, the simultaneous noninvasive recording of ECG and skin sympathetic nerve activity (SKNA), directly records sympathetic nerve activity over a long period of time. It can be used to measure sympathetic tone in healthy subjects and in subjects with non-cardiovascular diseases. The electrical activity that can be measured on the surface of the skin originates from the heart, the muscle or nerve structures. Because the frequency content of nerve activity falls in a higher frequency range than that of the ECG and myopotential, it is possible to use high-pass or band-pass filtering to specifically isolate the SKNA. neuECG is voltage calibrated and does not require invasive procedures to impale electrodes in nerves and thus has advantages over microneurography. Here, we present a protocol that takes <10 min to set up. The neuECG can be continuously recorded over a 24-h period or longer. We also describe methods to efficiently analyze neuECG from humans using commercially available hardware and software to facilitate adoption of this technology in clinical research. neuECG is the simultaneous noninvasive recording of ECG and skin sympathetic nerve activity and thus can directly record sympathetic nerve activity over a long period of time without the need for invasive procedures.

Background Long-term safety and reaccessibility following the use of suture-mediated vascular closure systems (SMC) for femoral vein access are not well documented. This study aimed to assess the long-term outcomes and feasibility of repeated femoral vein punctures after SMC. Methods We analyzed 282 patients who underwent elective catheter ablation via femoral vein access using an 8–13 Fr sheath. Patients were randomized into the pre-close or post-close groups using the ProGlide/ProStyle single-suture technique (Abbott Vascular). Duplex ultrasound evaluations were performed on day 1, day 90, and at 1 year to evaluate vascular complications. The primary and secondary endpoints included major and minor complications within 1 year. Reaccessibility was assessed in patients who required repeated procedures. Results Successful re-access was achieved in 21 patients (14.9%) in the pre-close group and 16 patients (11.3%) in the post-close group who underwent repeat procedures. Long-term safety was analyzed in 91 (64.5%) and 98 (69.5%) patients in the pre-close and post-close groups, respectively. The major complication rate was 2/189 (1.1%), and the minor complication rate was 28/189 (14.8%). No difference in complication rates was observed between the pre-close group (0/91, 0.0% major, 12/91, 13.2% minor) and post-close group (2/98, 2% major, 16/98, 16.3% minor), with P -values of 0.50 and 0.68, respectively. No new vascular stenosis occurred during the chronic phase in either group. Conclusion In the long-term follow-up after femoral vein access using SMC, new-onset chronic stenosis was not observed, and reaccess was possible in repeat procedures. Clinical trial registration: UMIN000049174. Graphical Abstract

Ablation index (AI)-guided ablation is useful for pulmonary vein isolation (PVI) and cavotricuspid isthmus (CTI) ablation. However, the impact of radiofrequency (RF) application power on CTI ablation with a fixed target AI remains unclear. One-hundred-thirty drug-refractory atrial fibrillation and/or atrial flutter patients who underwent AI-guided CTI ablation with or without PVI between July 2020 and August 2021 were randomly assigned to high-power (45 W) and moderate-power (35 W) groups. We performed CTI ablation with the same target AI value in both groups: 500 for the anterior 1/3 segments and 450 for the posterior 2/3 segments. In total, first-pass conduction block of the CTI was obtained in 111 patients (85.4%), with 7 patients (5.4%) showing CTI reconnection. The rate of first-pass conduction block was significantly higher in the 45 W group (61/65, 93.8%) than in the 35 W group (50/65, 76.9%, P = 0.01). CTI ablation and CTI fluoroscopy time were significantly shorter in the 45 W group than in the 35 W group (CTI ablation time: 192.3 ± 84.8 vs. 319.8 ± 171.4 s, P < 0.0001; CTI fluoroscopy time: 125.2 ± 122.4 vs. 171.2 ± 124.0 s, P = 0.039). Although there was no significant difference, steam pops were identified in two patients from the 45 W group at the anterior segment of the CTI. The 45 W ablation strategy was faster and provided a higher probability of first-pass conduction block than the 35 W ablation strategy for CTI ablation with a fixed AI target.

PurposeCatheter ablation (CA) to isolate the pulmonary vein, which is an established treatment for atrial fibrillation (AF), is associated with left atrium reverse remodeling (LARR). The intrinsic cardiac autonomic nervous system includes the ganglion plexi adjacent to the pulmonary vein in the left atrium (LA). However, little is known about the effect of CA on the relationship between LARR and sympathetic nerve activity in patients with AF.MethodsThis study enrolled 22 AF patients with a normal left ventricular ejection fraction (LVEF) aged 64.6 ± 12.9 years who were scheduled for CA. Sympathetic nerve activity was evaluated by direct recording of muscle sympathetic nerve activity (MSNA) before and 12 weeks after CA. Blood pressure, heart rate (HR), HR variability, and echocardiography were also measured.ResultsThe heart rate increased significantly after CA (63 ± 10.9 vs. 70.6 ± 7.7 beats/min, p < 0.01), but blood pressure did not change. A high frequency (HF) and low frequency (LF) of HR variability decreased significantly after ablation, but no significant change in LF/HF was observed. CA significantly decreased MSNA (38.9 ± 9.9 vs. 28 ± 9.1 bursts/min, p < 0.01). Moreover, regression analysis revealed a positive correlation between the percentage change in MSNA and the LA volume index (r = 0.442, p < 0.05).ConclusionsOur results show that CA for AF reduced MSNA and the decrease was associated with the LA volume index in AF patients with a normal LVEF. These findings suggest that LARR induced by CA for AF decrease sympathetic nerve activity.

Pulmonary vein isolation (PVI) is an established treatment for atrial fibrillation (AF). While it is known to affect the autonomic nervous system, the relationship between left atrial (LA) remodeling and PVI-mediated neuromodulation remains unclear. We aimed to assess the neuromodulatory effects of PVI using skin sympathetic nerve activity (SKNA). SKNA was recorded one day before and 2–3 days after PVI in 28 paroxysmal AF (PAF) and 33 persistent AF (PerAF) groups. Baseline low frequency to high frequency (LF/HF) ratio was higher in the PAF group (1.23 [interquartile range IQR: 0.79–1.76] vs. 0.74 [IQR: 0.49–1.38], p = 0.017). After PVI, the PAF group demonstrated significant reductions in burst amplitude (1.46 [IQR: 1.04–2.84] vs. 1.09 [IQR: 0.78–2.17] μV, p = 0.015) and LF/HF ratio (0.91 [IQR: 0.73–1.52] vs. 0.71 [IQR: 0.48–1.21], p = 0.012), whereas the PerAF group exhibited no such changes. A weak positive correlation was observed between the percentage change in LF/HF ratio and LA volume index in the PAF group (r = 0.572, p = 0.002). PVI significantly decreased SKNA in PAF patients but not in PerAF. LA remodeling may hinder the effectiveness of PVI-mediated neuromodulation.

While autonomic dysregulation and repolarization abnormalities are observed in subarachnoid hemorrhage (SAH), their relationship remains unclear. We aimed to measure skin sympathetic nerve activity (SKNA), a novel method to estimate stellate ganglion nerve activity, and investigate its association with electrocardiogram (ECG) alterations after SAH. We recorded a total of 179 SKNA data from SAH patients at three distinct phases and compared them with 20 data from controls. Compared with control data, in the acute phase data (days 1–3 of SAH), T peak‐to‐end (Tp‐e) interval was significantly prolonged (81 [interquartile range IQR: 71–93] vs. 58 [IQR: 54–64] ms, p < 0.001), non‐burst amplitude of SKNA was significantly increased (2.4 [IQR: 1.3–4.1] vs. 0.7 [IQR: 0.5–1.7] μV, p < 0.001), and the ratio of low frequency to high frequency (HF) was significantly decreased (0.8 [IQR: 0.5–1.1] vs. 1.1 [IQR: 0.7–1.3], p = 0.028). Linear mixed model revealed a relationship between Tp‐e interval and SKNA. Although these abnormalities gradually normalized, delayed cerebral ischemia episodes were associated with increased HF oscillation. Transient sympathetic dysregulation contributes to repolarization impairment after SAH. SKNA may have the potential to monitor adverse outcomes.

Selenoprotein P (SeP), a liver-derived secretory protein, functions as a selenium supply protein in the body. SeP has been reported to be associated with insulin resistance in humans through serial analysis of gene expression. Recently, SeP has been found to inhibit vascular endothelial growth factor-stimulated cell proliferation in human umbilical vein endothelial cells, and impair angiogenesis in a mouse hind limb model. In this study, the role of SeP in ischemia/reperfusion (I/R) injury has been investigated. SeP knockout (KO) and littermate wild-type (WT) mice were subjected to 30 min of myocardial ischemia followed by 24 h of reperfusion. The myocardial infarct area/area at risk (IA/AAR), evaluated using Evans blue (EB) and 2,3,5-triphenyltetrazolium chloride (TTC) staining, was significantly smaller in SeP KO mice than in WT mice. The number of terminal de-oxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive nuclei was significantly lower in SeP KO mice than in WT mice. In addition, caspase-3 activation was reduced in SeP KO mice compared to that in WT mice. Furthermore, phosphoinositide 3-kinase/Akt and Erk levels were examined for the reperfusion injury salvage kinase (RISK) pathway. Interestingly, SeP KO significantly increased the phosphorylation of IGF-1, Akt, and Erk compared to that in WT mice after I/R. Finally, I/R-induced myocardial IA/AAR was significantly increased in SeP KO mice overexpressing SeP in the liver compared to other SeP KO mice. These results, together, suggest that inhibition of SeP protects the heart from I/R injury through upregulation of the RISK pathway.

Fatty acid binding protein 4 (FABP4) is highly expressed in adipocytes. Lipolysis, caused by an elevated adrenergic input, has been suggested to contribute to elevated serum FABP4 levels in patients with cardiovascular diseases. However, the relationship between the serum FABP4 and efferent sympathetic nerve activity remains poorly understood. Twenty‐one healthy subjects (average age, 29.1 years; 15 men) performed an isometric handgrip (HG) exercise at 30% of the maximal voluntary contraction until they were fatigued. The beat‐by‐beat heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) were recorded. Blood samples were collected at rest and at the time of peak fatigue. The MSNA, HR, and systolic BP were significantly increased by the HG exercise (all, p < 0.05). MSNA was obtained from 14 patients. The change in the FABP4 on HG exercise was significantly correlated with the change in MSNA (bursts/100 heartbeats) (R = 0.808, p < 0.001) but not with changes in other parameters, which might, in part, reflect an association of efferent sympathetic drive with FABP4. Meanwhile, resting FABP4 levels were not associated with any parameters including MSNA, in healthy individuals. Future studies on patients with elevated sympathetic activity are warranted to examine the relationship further.

Background Atrial fibrillation (AF), the most frequently occurring sustained arrhythmia in patients with hypertrophic cardiomyopathy (HCM), is linked to poor quality of life and increased thromboembolic risk. Chronic kidney disease (CKD) and reduced kidney function are known cardiovascular risk factors; however, their contributions to new‐onset AF in patients with HCM remain unclear. Estimated glomerular filtration rate (eGFR) is a key marker for CKD management. This study aimed to elucidate the incidence of new‐onset AF and to identify predictive factors in patients with HCM. Methods We analyzed 198 patients with HCM (121 men; mean age, 58 ± 17 years) without prior AF. The incidence and predictors of new‐onset AF were evaluated with a focus on kidney function and left atrial (LA) size. Cox proportional hazards modeling was used to assess the associations. Results Impaired kidney function (eGFR < 60 mL/min/1.73 m2) was present in 35 patients (17.7%). Over a median follow‐up of 7.52 years, 43 patients (21.7%) developed new‐onset AF for an incidence rate of 2.8 per 100 person‐years. The multivariate analysis identified reduced eGFR and increased LA diameter (LAD) as independent predictors of AF. Kaplan–Meier curves showed a significantly higher cumulative AF incidence among patients with an eGFR ≤ 76.1 mL/min/1.73 m2 or an LAD ≥ 48.0 mm. Conclusions Decreased kidney function and LA dilatation were significantly associated with new‐onset AF among patients with HCM. These findings suggest that this patient population requires closer monitoring for the early detection of AF. New‐onset atrial fibrillation (AF) occurred in 22% of patients with hypertrophic cardiomyopathy, corresponding to an incidence rate of 2.8 per 100 person‐years. Reduced kidney function and left atrial dilatation were independently associated with AF onset, indicating the need for closer monitoring and regular renal assessments in this population.

The arterial velocity pulse index (AVI) and arterial pressure‐volume index (API) have been proposed as new arterial stiffness indices that can be measured using an oscillometric cuff. Sympathetic nerve activity (SNA) contributes to arterial stiffness via increasing vascular smooth muscle tone. However, the associations between SNA and the AVI or API are not understood. The purpose of this study was to evaluate the relationships between muscle sympathetic nerve activity (MSNA) and the AVI or API in healthy individuals and patients with hypertension (HT). Forty healthy individuals (40.1 ± 15.2 years, 8 females) (healthy group) and 40 patients with HT (60.2 ± 13.6, 18 females) (HT group) were included in this study. The AVI, API, MSNA, beat‐by‐beat blood pressure, and heart rate were recorded simultaneously. The AVI and API were higher in the HT group than in the healthy group (AVI, 26.1 ± 7.6 vs. 16.5 ± 4.0, p < 0.001; API, 31.2 ± 8.6 vs. 25.5 ± 7.2, p = 0.002). MSNA in the HT group was also higher than in the healthy group (p < 0.001). MSNA was correlated with the AVI, but not with the API, in both the healthy group (R = 0.52, p = 0.001) and HT group (R = 0.57, p < 0.001). MSNA was independently correlated with the AVI in multivariate analysis (ß = 0.34, p = 0.001). In conclusion, AVI, obtained by a simple and less user‐dependent method, was related to the MSNA in healthy individuals and patients with HT. Arterial velocity pulse index (AVI) is a novel arterial stiffness index that can be measured by a single oscillometric cuff. We found that AVI was significantly correlated with muscle sympathetic nerve activity (MSNA) in both healthy subjects and patients with hypertension, which is likely related to the influence of MSNA on arterial wave reflection.