Effect of pulmonary vein isolation on the relationship between left atrial reverse remodeling and sympathetic nerve activity in patients with atrial fibrillation.

PURPOSE: Catheter 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. METHODS: This 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. RESULTS: The 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). CONCLUSIONS: Our 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.

Takotsubo cardiomyopathy complicated by cardiac tamponade due to non-hemorrhagic pericardial effusion: a case report.

BACKGROUND: Cardiac tamponade is a rare but serious complication of Takotsubo cardiomyopathy (TC). Two cases of cardiac tamponade subsequent to TC have been reported. The pericardial effusion in these cases was hemorrhagic and caused by ventricular rupture. Cardiac tamponade induced by an inflammatory effusion complicated with TC has not been reported. This is the first case report of TC, which developed cardiac tamponade during the recovery phase with a large volume non-hemorrhagic inflammatory effusion. CASE PRESENTATION: We describe a case of an 81-year-old woman admitted to our hospital because of severe chest pain. Her symptoms began soon after her son's hospitalization. We diagnosed her with TC based on results of an electrocardiogram, echocardiogram, and emergent coronary angiography. Her symptoms and left ventricular dysfunction improved gradually. She developed newly confirmed chest pain and dyspnea on day 9 after admission. A large pericardial effusion developed, resulting in cardiac tamponade. Her symptoms and hemodynamic status improved immediately after the pericardiocentesis. The effusion was non-hemorrhagic and exudative. No specific signs of infection, collagen disease, or malignant tumors were observed, except for TC. CONCLUSIONS: We experienced a case of circulatory collapse induced by TC-related inflammatory pericardial effusion at recovery phase. This case emphasizes the importance of careful follow-up even after improved left ventricular dysfunction in a patient with TC.

Endogenous muscle atrophy F-box is involved in the development of cardiac rupture after myocardial infarction.

Muscle atrophy F-box (MAFbx/atrogin-1), an E3 ubiquitin ligase, is a crucial mediator of skeletal muscle atrophy and cardiac hypertrophy in response to pressure overload and exercise. The role of MAFbx in the regulation of cardiac remodeling after myocardial infarction (MI) remains unclear. Permanent coronary ligation of the left coronary artery was performed on MAFbx knockout (KO) and wild-type (WT) mice and MAFbx expression in the WT mice was shown to be significantly increased in the left ventricles after MI. The mortality rate due to post-MI cardiac rupture was significantly decreased in MAFbx KO mice compared to that in the WT mice. DNA microarray and mRNA expression analyses revealed that the upregulation of genes involved in inflammatory processes and cell motility of leukocytes and neutrophils, including Mmp9, Il1b, Cxcl2, and Nlrp3, was significantly attenuated in MAFbx KO mice 1 day after MI. MAFbx downregulation inhibited nuclear factor-κB (Nfkb) activation after MI. Flow cytometry results demonstrated that the myocardial infiltration of neutrophils was suppressed in MAFbx KO mice 1 day after MI. Nlrp3 and Il1b protein levels were decreased in MAFbx KO mice compared with those in the WT mice. MAFbx downregulation significantly attenuated Tnfa-induced Cxcl2, Il1b, and Nlrp3 expression in cardiomyocytes. We conclude that MAFbx plays an important role in the mediation of excessive inflammation, including neutrophil infiltration, inflammasome formation, and production of proinflammatory cytokines through the activation of Nfkb, promoting cardiac rupture after MI.

Diabetes impairs the angiogenic capacity of human adipose-derived stem cells by reducing the CD271+ subpopulation in adipose tissue.

Type 2 diabetes mellitus is an important risk factor for cardiovascular diseases (CVDs). Therapeutic angiogenesis using adipose-derived stem cells (ADSCs) is attractive for CVD therapy. However, although it would be critical for ADSC application on CVD therapy, whether and how diabetes impairs human ADSC therapeutic potential is still uncertain. In this study, we aimed to investigate the impact of diabetes on the angiogenic potential of ADSCs in patients with CVDs, with special focus on stemness-related genes and cellular alteration of ADSCs. We established cultured ADSCs from diabetic (DM-ADSCs) and non-diabetic patients (nonDM-ADSCs) with CVDs. DM-ADSCs demonstrated limited proliferative capacity and reduced paracrine capacity of VEGF, with lower expression of the stemness gene SOX2. Angiogenic capacity and ADSC engraftment were assessed using xenograft experiments in a hindlimb ischemia model of athymic nude mice. Consistent with the results of in vitro assays, DM-ADSCs did not rescue limb ischemia. In contrast, nonDM-ADSCs induced neovascularization with enhanced engraftment. To elucidate the mechanism underlying these ADSC changes, we compared the surface marker profiles of freshly isolated ADSCs obtained from diabetic and non-diabetic patients by flow cytometry. Among studied subsets, the CD34+CD31-CD271+ subpopulation was reduced in the adipose tissues of diabetic patients. In addition, SOX2 expression and proliferative capacity were considerably reduced in nonDM-ADSCs derived from the stromal vascular fraction (SVF) with depletion of CD271+ cells (p < 0.01). Our observations elucidated that reduced CD271+ subpopulation is critical for the impairment of ADSCs in diabetic patients. Further investigations on the CD271+ subset of ADSCs might provide novel insights into the mechanisms and solutions for diabetes-related ADSC dysfunction in cell therapy.

Training heart failure patients with reduced ejection fraction attenuates muscle sympathetic nerve activation during mild dynamic exercise.

Muscle sympathetic nerve activity (MSNA) decreases during low-intensity dynamic one-leg exercise in healthy subjects but increases in patients with heart failure with reduced ejection fraction (HFrEF). We hypothesized that increased peak oxygen uptake (V̇o2peak) after aerobic training would be accompanied by less sympathoexcitation during both mild and moderate one-leg dynamic cycling, an attenuated muscle metaboreflex, and greater skin vasodilation. We studied 27 stable, treated HFrEF patients (6 women; mean age: 65 ± 2 SE yr; mean left ventricular ejection fraction: 30 ± 1%) and 18 healthy age-matched volunteers (6 women; mean age: 57 ± 2 yr). We assessed V̇o2peak (open-circuit spirometry) and the skin microcirculatory response to reactive hyperemia (laser flowmetry). Fibular MSNA (microneurography) was recorded before and during one-leg cycling (2 min unloaded and 2 min at 50% of V̇o2peak) and, to assess the muscle metaboreflex, during posthandgrip ischemia (PHGI). HFrEF patients were evaluated before and after 6 mo of exercise-based cardiac rehabilitation. Pretraining V̇o2peak and skin vasodilatation were lower (P < 0.001) and resting MSNA higher (P = 0.01) in HFrEF than control subjects. Training improved V̇o2peak (+3.0 ± 1.0 mL·kg-1·min-1; P < 0.001) and cutaneous vasodilation and diminished resting MSNA (-6.0 ± 2.0, P = 0.01) plus exercise MSNA during unloaded (-4.0 ± 2.5, P = 0.04) but not loaded cycling (-1.0 ± 4.0 bursts/min, P = 0.34) and MSNA during PHGI (P < 0.05). In HFrEF patients, exercise training lowers MSNA at rest, desensitizes the sympathoexcitatory metaboreflex, and diminishes MSNA elicited by mild but not moderate cycling. Training-induced downregulation of resting MSNA and attenuated reflex sympathetic excitation may improve exercise capacity and survival.

Coronary sinus catheter placement via left cubital vein for phrenic nerve stimulation during pulmonary vein isolation.

Phrenic nerve (PN) stimulation is essential for the elimination of PN palsy during balloon-based pulmonary vein isolation (PVI). Although ultrasound-guided vascular access is safe, insertion of a PN stimulation catheter via central venous access carries a potential risk of the development of mechanical complications. We evaluated the safety of a left cubital vein approach for positioning a 20-electrode atrial cardioversion (BeeAT) catheter in the coronary sinus (CS), and the feasibility of right PN pacing from the superior vena cava (SVC) using proximal electrodes of the BeeAT catheter. In total, 106 consecutive patients who underwent balloon-based PVI with a left cubital vein approach for BeeAT catheter positioning were retrospectively assessed. The left cubital approach was successful in 105 patients (99.1%), and catheter insertion into the CS was possible for 104 patients (99.0%). Among these patients, constant right PN pacing from the SVC was obtained for 89 patients (89/104, 85.6%). In five patients, transient loss of right PN capture occurred during right pulmonary vein ablation. No persistent right PN palsy was observed. Small subcutaneous hemorrhage was observed in eight patients (7.5%). Neuropathy, pseudoaneurysm, arteriovenous fistula, and perforations associated with the left cubital approach were not detected. Body mass index was significantly higher in the right PN pacing failure group than in the right PN pacing success group (26.2 ± 3.2 vs. 23.8 ± 3.8; P = 0.025). CS catheter placement with a left cubital vein approach for right PN stimulation was found to be safe and feasible. Right PN pacing from the SVC using a BeeAT catheter was successfully achieved in the majority of the patients. This approach may prove to be preferable for non-obese patients.

Optimal lesion size index to prevent conduction gap during pulmonary vein isolation.

INTRODUCTION: A novel real-time lesion size index (LSI) that incorporates contact force (CF), time, and power has been developed for safe and effective catheter ablation. The optimal LSI was evaluated to eliminate gap formation during pulmonary vein isolation (PVI). METHODS AND RESULTS: Consecutive patients were enrolled, who underwent their first PVI using a fiber-optic CF-sensing catheter for atrial fibrillation between December 2016 and October 2017. The CF parameters, force-time integral (FTI), and LSI for 3095 ablation points in 34 patients were evaluated. The FTI and LSI in the lesions with gaps or dormant conduction (gaps/DC) were significantly lower than those in the lesion without gaps/DC (FTI: 140.5 ± 54.5 and 232.4 ± 121.4 g s, P < 0.0001; LSI: 4.0 ± 0.6 and 4.7 ± 0.9, P < 0.0001, respectively). On receiver operating characteristic curve analysis, the optimal LSI threshold was 4.05 (sensitivity, 63.4%; specificity, 76.3%). The LSI of <5.25 predicted a gap or DC with a high sensitivity (sensitivity, 97.6%; specificity, 25.7%). In the posterior wall, which was 37% thinner than the nonposterior wall, a lower LSI of <3.95 showed a relatively high sensitivity (92.3%) and specificity (65.6%). CONCLUSIONS: The LSI can be used to predict gaps/DC during the PVI procedure. An LSI of 5.2 may be a suitable target for effective lesion formation. An LSI of 4.0 may be acceptable in the posterior wall, especially in areas adjacent to the esophagus.

Significant Association Between Coronary Artery Low-Attenuation Plaque Volume and Apnea-Hypopnea Index, But Not Muscle Sympathetic Nerve Activity, in Patients With Obstructive Sleep Apnea Syndrome.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is associated with augmented sympathetic nerve activity and cardiovascular diseases. However, the interaction between coronary artery plaque characteristics and sympathetic nerve activity remains unclear. The purpose of this study was to clarify the relationships between coronary artery plaque characteristics, sleep parameters and single- and multi-unit muscle sympathetic nerve activity (MSNA) in OSAS patients. Methods and Results: A total of 32 OSAS patients who underwent full-polysomnography participated in this study. The coronary plaque volume was calculated with 320-slice coronary computed tomography (CT). Single- and multi-unit MSNA were obtained during the daytime within 1 week from full-polysomnography. Patients were divided into 2 groups according to their apnea-hypopnea index (AHI) score (mild-moderate group, AHI <30; and severe group, AHI ≥30). There were no group differences in risk factors for atherosclerosis; however, severe AHI patients showed significantly high single-unit MSNA, and low- and intermediate-attenuation plaque volumes. In regression analysis, the plaque volume of any CT value was not associated with single- or multi-unit MSNA; only AHI significantly correlated with low-attenuation plaque volume (R=0.52, P<0.05). CONCLUSIONS: Our findings provided the evidence that AHI is an independent predictor for low-attenuated, vulnerable plaque volume, but not daytime MSNA, in patients with OSAS.

Occult constrictive pericardial disease emerging 40 years after chest radiation therapy: a case report.

BACKGROUND: The main etiology of constrictive pericarditis (CP) has changed from tuberculosis to therapeutic mediastinal radiation and cardiac surgery. Occult constrictive pericardial disease (OCPD) is a covert disease in which CP is manifested in a condition of volume overload. CASE PRESENTATION: A 60-year-old patient with a history of thoracic radiation therapy for non-Hodgkin's lymphoma (40 years earlier) was transferred to our hospital for treatment of repeated congestive heart failure. For a preoperative hemodynamic study, pre-hydration with intravenous normal saline (50 mL/hour) was used to manifest the pericardial disease and prevent contrast-induced nephropathy. The hemodynamic study showed a right ventricular dip-plateau pattern and discordance of right and left ventricular systolic pressures during inspiration, which was not seen in the volume-controlled state. These responses were concordant with OCPD. A pericardiectomy, aortic valve replacement, and mitral and tricuspid valve repair were performed. Postoperatively, the heart failure was controlled with standard medication. CONCLUSIONS: This case revealed a volume-induced change in hemodynamics in OCPD with severe combined valvular heart disease, which suggests the importance of considering OCPD in patients who had undergone radiation therapy 40 years before.

Evaluation of the risk factors for ventricular arrhythmias secondary to QT prolongation induced by papaverine injection during coronary flow reserve studies using a 4 Fr angio-catheter.

Estimation of the fractional flow reserve (FFR) is considered to be an established method by which to assess stable coronary artery stenosis. Induction of maximal coronary hyperemia is important during the FFR procedure. Papaverine has been reported to increase the risk of ventricular arrhythmia (VA). The purpose of the present study was to discover predictors of papaverine-induced VAs developing during FFR measurement. A total of 213 clinically stable patients were included in the study. FFRs were determined after intracoronary papaverine administration (12 mg into the left and 8 mg into the right coronary arteries). We compared patients in whom VA did and did not develop in terms of clinical and electrocardiogram characteristics. FFR measurements were performed on 244 lesions (133 in the left anterior descending arteries, 43 in the left circumflex arteries, and 68 in the right coronary arteries). We found that the QTc interval was prolonged in all patients after papaverine administration (average post-administration QTc interval = 569 ± 89 ms; average ΔQTc interval = 144 ± 80 ms). VA developed in three patients with significantly prolonged QT intervals (average post-administration QTc interval = 639 ± 19 ms, average ΔQTc interval = 220 ± 64 ms, p < 0.02) and transitioned from torsade de pointes to ventricular fibrillation. Bradycardia (< 50 beats/min), hypokalemia (serum K < 3.5 mEp/L), and low left ventricular function (ejection fraction (EF) < 50%) were associated with VA (bradycardia, p < 0.01; hypokalemia, p < 0.01; low left ventricular function, p < 0.01). Three-vessel disease was significantly predictive of VA (p < 0.003). In the three-vessel group, the complications of low left ventricular function, hypokalemia, and bradycardia were significantly associated with VA (p < 0.045). Three-vessel disease is a predictor of the development of VA during FFR measurement performed with the aid of papaverine, especially if accompanied by one or more of the following: low left ventricular function, hypokalemia, or bradycardia.

Endogenous Selenoprotein P, a Liver-Derived Secretory Protein, Mediates Myocardial Ischemia/Reperfusion Injury in Mice.

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.

Significant correlation between renal 123I-metaiodobenzylguanidine scintigraphy and muscle sympathetic nerve activity in patients with primary hypertension.

BACKGROUND: Iodine-123 metaiodobenzylguanidine (123I-MIBG) scintigraphy is used as a noninvasive imaging method for assessing cardiac sympathetic nerve activity. We tested the hypothesis that renal 123I-MIBG imaging is correlated with muscle sympathetic nerve activity (MSNA) in patients with primary hypertension. METHODS: Thirty-one consecutive patients with primary hypertension were included. Multiunit MSNA was recorded from the peroneal nerve to evaluate direct efferent sympathetic nerve activity. Planar renal and cardiac 123I-MIBG images were acquired. Early and delayed kidney-to-mediastinum ratio (K/M), early and delayed heart-to-mediastinum ratio (H/M), and washout rates (WR) were calculated. RESULTS: In 27 of 31 patients, blood pressure was controlled on antihypertensive medication. Mean systolic and diastolic blood pressures were 118 ± 18 and 67 ± 15 mmHg, respectively. Although early and late K/M and H/M were not significantly correlated with MSNA, both cardiac and average renal WR were significantly correlated with MSNA (r = 0.45, P = .0035 and r = 0.68, P < .001, respectively). Right and left renal WR were similarly correlated with MSNA. Renal WR was significantly higher than cardiac WR (43.2% vs 25.8%, P < .001) in these patients with hypertension. CONCLUSIONS: Renal 123I-MIBG WR was significantly associated with multiunit MSNA. Renal 123I-MIBG imaging offers a noninvasive clinical methodology for assessing renal sympathetic nerve function.

General anesthesia improves contact force and reduces gap formation in pulmonary vein isolation: a comparison with conscious sedation.

Compared to conscious sedation (CS), the use of general anesthesia (GA) in pulmonary vein isolation (PVI) is associated with a lower recurrence rate of atrial fibrillation (AF). GA may improve catheter stability and mapping system accuracy compared to CS, but its influence on contact force (CF) parameters during ipsilateral PVI has not previously been investigated. The study population comprised 176 consecutive patients (107 in GA group and 69 in CS group) with AF who underwent their first PVI procedure. We retrospectively assessed CF parameters, force-time integral (FTI), FTI/wall thickness during anatomical ipsilateral PVI and long-term outcome after ablation. Complete PVI with single continuous circular lesions around the ipsilateral PVs was achieved in 54 patients (50.5%) in the GA group but only 24 patients (34.8%) in the CS group (P = 0.04). The distribution of gaps did not differ between the groups. All CF parameters were significantly higher in the GA group than in the CS group (average CF: 19.4 ± 8.7 vs. 16.7 ± 7.7 g, P < 0.0001; FTI: 399.0 ± 262.5 vs. 293.9 ± 193.4 gs, P < 0.0001; FTI/wall thickness: 155.5 ± 106.1 vs. 115.7 ± 85.5 gs, P < 0.0001). GA was associated with lower AF recurrence rate in patients with paroxysmal AF but not with persistent AF. Compared with CS, GA improves CF parameters, FTI and FTI/wall thickness, and reduced gap formation after ipsilateral PVI.

Paradoxical muscle sympathetic reflex activation in human heart failure.

BACKGROUND: Muscle sympathetic activation in heart failure with reduced ejection fraction (HFrEF) has been attributed, on the basis of multiunit recordings, to attenuated inhibitory feedback from stretch-sensitive cardiopulmonary mechanoreceptors. However, such preparations integrate 2 populations of single units exhibiting directionally opposite firing when atrial pressure is perturbed. We tested the hypothesis that the proportion of single units firing paradoxically when filling pressure increases is augmented in HFrEF. METHODS AND RESULTS: Muscle sympathetic nerve activity and estimated central venous pressure were recorded during nonhypotensive lower body negative pressure (LBNP; -10 mm Hg) and nonhypertensive positive pressure (LBPP; +10 mm Hg) in 11 treated HFrEF (left ventricular ejection fraction 25 ± 6% [mean ± standard deviation]) patients and 14 similarly aged controls. Single-unit muscle sympathetic nerve activity discharge was termed either anticipated, if firing frequency exhibited classic negative-feedback responses, or paradoxical. LBNP and LBPP had no heart rate, stroke volume, or blood pressure effects (P>0.05). Estimated central venous pressure decreased with LBNP (P<0.05), increased with LBPP (P<0.05), and was consistently higher in HFrEF (P<0.05). During LBNP, the ratio of single units with anticipated and paradoxical discharge was similar in HFrEF (18:7) and controls (27:5), whereas LBPP elicited paradoxical reflex excitation in a greater proportion of HFrEF single units (7:18 versus 24:6; P=0.0001). Consequently, LBPP increased mean single-unit firing frequency (P<0.05) and did not inhibit multiunit muscle sympathetic nerve activity of HFrEF subjects (P<0.05 versus controls). Firing of 12/18 HFrEF (but no control) single units increased during both LBPP and LBNP. CONCLUSION: These findings provide the first evidence in human HFrEF for an augmented excitatory cardiopulmonary-muscle sympathetic nerve activity reflex response to increased preload, incorporating 2 distinct single-unit populations with differing firing properties.

Association between resting-state brain functional connectivity and muscle sympathetic burst incidence.

The insula (IC) and cingulate are key components of the central autonomic network and central nodes of the salience network (SN), a set of spatially distinct but temporally correlated brain regions identified with resting-state (task free) functional MRI (rsMRI). To examine the SN's involvement in sympathetic outflow, we tested the hypothesis that individual differences in intrinsic connectivity of the SN correlate positively with resting postganglionic muscle sympathetic nerve activity (MSNA) burst incidence (BI) in subjects without and with obstructive sleep apnea (OSA). Overnight polysomnography, 5-min rsMRI, and fibular MSNA recording were performed in 36 subjects (mean age 57 yr; 10 women, 26 men). Independent component analysis (ICA) of the entire cohort identified the SN as including bilateral IC, pregenual anterior cingulate cortex (pgACC), midcingulate cortex (MCC), and the temporoparietal junction (TPJ). There was a positive correlation between BI and the apnea-hypopnea index (AHI) (P < 0.001), but dual-regression analysis identified no differences in SN functional connectivity between subjects with no or mild OSA (n = 17) and moderate or severe (n = 19) OSA. Correlation analysis relating BI to the strength of connectivity within the SN revealed large (i.e., spatial extent) and strong correlations for the left IC (P < 0.001), right pgACC/MCC (P < 0.006), left TPJ (P < 0.004), thalamus (P < 0.035), and cerebellum (P < 0.013). Indexes of sleep apnea were unrelated to BI and the strength of SN connectivity. There were no relationships between BI and default or sensorimotor network connectivity. This study links connectivity within the SN to MSNA, demonstrating several of its nodes to be key sympathoexcitatory regions.

Case report: pericardial effusion with constrictive physiology in a patient with wet beriberi.

Wet beriberi-induced pericardial effusion has rarely been previously described. Little is known about the effect of beriberi-induced pericardial effusion on hemodynamics. Here we present a case of wet beriberi with pericardial effusion that exhibited constrictive physiology, which was dramatically improved after treatment. A 61-year-old male patient was admitted to our hospital for progressive leg edema, dyspnea on exertion, and lower-extremity muscle weakness. Echocardiography showed a hyperkinetic left ventricle and a moderate amount of pericardial effusion. Hemodynamic measurements, including simultaneous measurement of left and right ventricular pressures, revealed high output heart failure and constrictive physiology. Blood test showed lactic acidosis, and low level of serum thiamine levels; consistent with a diagnosis of wet beriberi. After thiamine replacement therapy, the patient's hemodynamic state rapidly improved. Additionally, pericardial effusion decreased and constrictive physiology was successfully resolved. No other possible causes of pericardial effusion could be identified, with the exception of thiamine deficiency. This case illustrates the importance of considering wet beriberi as a possible cause of pericardial effusion with constrictive physiology.

Divergent muscle sympathetic responses to dynamic leg exercise in heart failure and age-matched healthy subjects.

KEY POINTS: People with diminished ventricular contraction who develop heart failure have higher sympathetic nerve firing rates at rest compared with healthy individuals of a similar age and this is associated with less exercise capacity. During handgrip exercise, sympathetic nerve activity to muscle is higher in patients with heart failure but the response to leg exercise is unknown because its recording requires stillness. We measured sympathetic activity from one leg while the other leg cycled at a moderate level and observed a decrease in nerve firing rate in healthy subjects but an increase in subjects with heart failure. Because these nerves release noradrenaline, which can restrict muscle blood flow, this observation helps explain the limited exercise capacity of patients with heart failure. Lower nerve traffic during exercise was associated with greater peak oxygen uptake, suggesting that if exercise training attenuated sympathetic outflow functional capacity in heart failure would improve. ABSTRACT: The reflex fibular muscle sympathetic nerve (MSNA) response to dynamic handgrip exercise is elicited at a lower threshold in heart failure with reduced ejection fraction (HFrEF). The present aim was to test the hypothesis that the contralateral MSNA response to mild to moderate dynamic one-legged exercise is augmented in HFrEF relative to age- and sex-matched controls. Heart rate (HR), blood pressure and MSNA were recorded in 16 patients with HFrEF (left ventricular ejection fraction = 31 ± 2%; age 62 ± 3 years, mean ± SE) and 13 healthy control subjects (56 ± 2 years) before and during 2 min of upright one-legged unloaded cycling followed by 2 min at 50% of peak oxygen uptake (V̇O2,peak). Resting HR and blood pressure were similar between groups whereas MSNA burst frequency was higher (50.0 ± 2.0 vs. 42.3 ± 2.7 bursts min(-1), P = 0.03) and V̇O2,peak lower (18.0 ± 2.0 vs. 32.6 ± 2.8 ml kg(-1) min(-1), P < 0.001) in HFrEF. Exercise increased HR (P < 0.001) with no group difference (P = 0.1). MSNA burst frequency decreased during mild to moderate dynamic exercise in the healthy controls but increased in HFrEF (-5.5 ± 2.0 vs. 6.9 ± 1.8 bursts min(-1), P < 0.001). Exercise capacity correlated inversely with MSNA burst frequency at 50% V̇O2,peak (n = 29; r = -0.64; P < 0.001). At the same relative workload, one-legged dynamic exercise elicited a fall in MSNA burst frequency in healthy subjects but sympathoexcitation in HFrEF, a divergence probably reflecting between-group differences in reflexes engaged by cycling. This finding, coupled with an inverse relationship between MSNA burst frequency during loaded cycling and subjects' V̇O2,peak, is consistent with a neurogenic determinant of exercise capacity in HFrEF.

Study Protocol for the Pleiotropic Effects of Sodium-Glucose Cotransporter 2 Inhibitor on Organ-Specific Sympathetic Nerve Activity and Insulin Sensitivity in Participants with Type 2 Diabetes.

INTRODUCTION: Hyperinsulinemia and hyperglycemia are associated with exaggerated systemic sympathetic nerve activity (SNA) in patients with type 2 diabetes. Sodium-glucose cotransporter 2 (SGLT2) inhibitors lower insulin levels, whereas sulfonylureas increase insulin levels. We will test whether these two classes of antidiabetic agents have different effects on SNA. METHODS: The present study is an ongoing, 24-week, one-center (only Kanazawa University Hospital), open-label, randomized, parallel trial (jRCTs 041200035). Participants with type 2 diabetes with multiple atherosclerosis risk factors are randomly assigned in a 1:1 manner to receive 2.5 mg luseogliflozin or 0.5 mg glimepiride once daily. The sample size was calculated to be 14 in each group, with a significance level of 0.05 and a power of 0.80. The design required 40 evaluable study participants. Our primary endpoint will be the change in muscle SNA (MSNA). The secondary endpoints included organ-specific insulin sensitivity measured by a hyperinsulinemic-euglycemic clamp study using an artificial pancreas combined with a stable isotope-labeled glucose infusion, bioelectrical impedance analysis, and organ-specific (cardiac, renal, and hepatic) 123I-meta-iodobenzylguanidine (MIBG) innervation imaging. PLANNED OUTCOMES: Study recruitment started in April 2020 and will end in June 2024, with 40 participants randomized into the two groups. The treatment follow-up of the participants is currently ongoing and is due to finish by March 2025. TRIAL REGISTRATION: The study protocol has been approved by the Certified Review Board, Kanazawa University, Ishikawa, Japan, in accordance with the guidelines stipulated in the Declaration of Helsinki (CRB4180005, 2019-001). This trial is registered with the Japan Registry of Clinical Trials, jRCTs 041200035.

Microneurographic evidence in healthy middle-aged humans for a sympathoexcitatory reflex activated by atrial pressure.

Atrial mechanoreceptors, stimulated by increased pressure or volume, elicit in healthy humans a net sympathoinhibitory response. The co-existence of an atrial reflex eliciting muscle sympathoexcitation has been postulated but undetected by conventional multi-unit muscle sympathetic nerve activity (MSNA). We hypothesized that in response to a selective increase in atrial pressure, single-unit MSNA would reveal a subpopulation of efferent sympathetic neurons with firing patterns opposite to the integrated multi-unit MSNA envelope. Multi- and single-unit MSNA recordings were acquired in eight healthy middle-aged subjects (age, 57 ± 8 years; body mass index, 25 ± 2 kg/m(2)) submitted to selective decreases or increases in atrial pressure by nonhypotensive lower body negative pressure (LBNP; -10 mmHg) or nonhypertensive lower body positive pressure (LBPP; +10 mmHg), respectively. Single-unit MSNA firing responses were classified as anticipated if spike frequency and incidence increased with LBNP or decreased with LBPP and paradoxical if they decreased with LBNP or increased with LBPP. LBNP decreased (3.2 ± 2.8 to 1.4 ± 3.1 mmHg, P < 0.01) and LBPP increased (3.3 ± 2.7 to 4.9 ± 2.8 mmHg, P < 0.01) estimated central venous pressure without affecting stroke volume, systemic pressure, or resistance. Multi-unit MSNA increased with LBNP (31 ± 17 to 38 ± 19 bursts/min, P < 0.01) and diminished with LBPP (33 ± 15 to 28 ± 15 bursts/min, P < 0.01). Of 21 single-units identified, 76% exhibited firing responses to both LBNP and LBPP concordant with multi-unit MSNA, whereas 24% demonstrated discordant or paradoxical responses. The detection of two subpopulations of single-units within the multi-unit MSNA recording, exhibiting opposite firing characteristics, establishes the first evidence in humans for the existence of an excitatory cardiac-muscle sympathetic reflex activated by increasing atrial pressure.