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1.
Physiol Rep ; 12(6): e15957, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38546216

RESUMO

Epicardial adipose tissue (EAT) is an active endocrine organ that is closely associated with occurrence of atrial fibrillation (AF). However, the role of EAT in the development of postoperative AF (POAF) remains unclear. We aimed to investigate the association between EAT profile and POAF occurrence in patients who underwent cardiovascular surgery. We obtained EAT samples from 53 patients to evaluate gene expression, histological changes, mitochondrial oxidative phosphorylation (OXPHOS) capacity in the EAT, and protein secretion in EAT-conditioned medium. EAT volume was measured using computed tomography scan. Eighteen patients (34%) experienced POAF within 7 days after surgery. Although no significant difference was observed in EAT profile between patients with and without POAF, logistic regression analysis identified that the mRNA expression levels of tumor necrosis factor-alpha (TNF-α) were positively correlated and adipocyte size in the EAT was inversely correlated with onset of POAF, respectively. Mitochondrial OXPHOS capacity in the EAT was not associated with POAF occurrence; however, it showed an inverse correlation with adipocyte size and a positive correlation with adiponectin secretion. In conclusion, changes in the secretory profile and adipocyte morphology of the EAT, which represent qualitative aspects of the adipose tissue, were present before the onset of AF.


Assuntos
Fibrilação Atrial , Humanos , Fibrilação Atrial/metabolismo , 60428 , Adipócitos/metabolismo , Tecido Adiposo/metabolismo , Inflamação/metabolismo , Pericárdio/metabolismo
3.
J Mol Cell Cardiol ; 178: 9-21, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36965700

RESUMO

AIMS: The most efficient way to acutely restore sinus rhythm from atrial fibrillation (AF) is electrical cardioversion, which is painful without adequate sedation. Recent studies in various experimental models have indicated that optogenetic termination of AF using light-gated ion channels may provide a myocardium-specific and potentially painless alternative future therapy. However, its underlying mechanism(s) remain(s) incompletely understood. As brief pulsed light stimulation, even without global illumination, can achieve optogenetic AF termination, besides direct conduction block also modulation of action potential (AP) properties may be involved in the termination mechanism. We studied the relationship between optogenetic AP duration (APD) and effective refractory period (ERP) prolongation by brief pulsed light stimulation and termination of atrial tachyarrhythmia (AT). METHODS AND RESULTS: Hearts from transgenic mice expressing the H134R variant of channelrhodopsin-2 in atrial myocytes were explanted and perfused retrogradely. AT induced by electrical stimulation was terminated by brief pulsed blue light stimulation (470 nm, 10 ms, 16 mW/mm2) with 68% efficacy. The termination rate was dependent on pulse duration and light intensity. Optogenetically imposed APD and ERP changes were systematically examined and optically monitored. Brief pulsed light stimulation (10 ms, 6 mW/mm2) consistently prolonged APD and ERP when light was applied at different phases of the cardiac action potential. Optical tracing showed light-induced APD prolongation during the termination of AT. CONCLUSION: Our results directly demonstrate that cationic channelrhodopsin activation by brief pulsed light stimulation prolongs the atrial refractory period suggesting that this is one of the key mechanisms of optogenetic termination of AT.


Assuntos
Fibrilação Atrial , Animais , Camundongos , Fibrilação Atrial/terapia , Optogenética/métodos , Channelrhodopsins/genética , Átrios do Coração , Taquicardia , Camundongos Transgênicos , Potenciais de Ação
4.
Front Cardiovasc Med ; 10: 1005408, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36815024

RESUMO

Introduction: Recent studies have demonstrated that sodium-glucose co-transporter-2 inhibitors (SGLT2-i) reduce the risk of atrial fibrillation (AF) in patients with diabetes mellitus (DM), in which oxidative stress due to increased reactive oxygen species (ROS) contributes to the pathogenesis of AF. We aimed to further investigate this, and examine whether the SGLT2-i empagliflozin suppresses mitochondrial-ROS generation and mitigates fibrosis. Methods: A high-fat diet and low-dose streptozotocin treatment were used to induce type-2 DM (T2DM) in Sprague-Dawley rats. The rats were randomly divided into three groups: control, DM, and DM treated with empagliflozin (30 mg/kg/day) for 8 weeks. The mitochondrial respiratory capacity and ROS generation in the atrial myocardium were measured using a high-resolution respirometer. Oxidative stress markers and protein expression related to mitochondrial biogenesis and dynamics as well as the mitochondrial morphology were examined in the atrial tissue. Additionally, mitochondrial function was examined in H9c2 cardiomyoblasts. Atrial tachyarrhythmia (ATA) inducibility, interatrial conduction time (IACT), and fibrosis were also measured. Results: Inducibility of ATA, fibrosis, and IACT were increased in rats with DM when compared to controls, all of which were restored by empagliflozin treatment. In addition, the rats with DM had increased mitochondrial-ROS with an impaired complex I-linked oxidative phosphorylation capacity. Importantly, empagliflozin seemed to ameliorate these impairments in mitochondrial function. Furthermore, empagliflozin reversed the decrease in phosphorylated AMPK expression and altered protein levels related to mitochondrial biogenesis and dynamics, and increased mitochondrial content. Empagliflozin also improved mitochondrial function in H9c2 cells cultured with high glucose medium. Discussion: These data suggest that empagliflozin has a cardioprotective effect, at least in part, by reducing mitochondrial ROS generation through AMPK signaling pathways in the atrium of diabetic rats. This suggests that empagliflozin might suppress the development of AF in T2DM.

5.
Am J Physiol Heart Circ Physiol ; 324(3): H341-H354, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36607794

RESUMO

Diabetic cardiomyopathy has been reported to increase the risk of fatal ventricular arrhythmia. The beneficial effects of the selective sodium-glucose cotransporter-2 inhibitor have not been fully examined in the context of antiarrhythmic therapy, especially its direct cardioprotective effects despite the negligible SGLT2 expression in cardiomyocytes. We aimed to examine the antiarrhythmic effects of empagliflozin (EMPA) treatment on diabetic cardiomyocytes, with a special focus on Ca2+ handling. We conducted echocardiography and hemodynamic studies and studied electrophysiology, Ca2+ handling, and protein expression in C57BLKS/J-leprdb/db mice (db/db mice) and their nondiabetic lean heterozygous Leprdb/+ littermates (db/+ mice). Preserved systolic function with diastolic dysfunction was observed in 16-wk-old db/db mice. During arrhythmia induction, db/db mice had significantly increased premature ventricular complexes (PVCs) than controls, which was attenuated by EMPA. In protein expression analyses, calmodulin-dependent protein kinase II (CaMKII) Thr287 autophosphorylation and CaMKII-dependent RyR2 phosphorylation (S2814) were significantly increased in diabetic hearts, which were inhibited by EMPA. In addition, global O-GlcNAcylation significantly decreased with EMPA treatment. Furthermore, EMPA significantly inhibited ventricular cardiomyocyte glucose uptake. Diabetic cardiomyocytes exhibited increased spontaneous Ca2+ events and decreased sarcoplasmic reticulum (SR) Ca2+ content, along with impaired Ca2+ transient, all of which normalized with EMPA treatment. Notably, most EMPA-induced improvements in Ca2+ handling were abolished by the addition of an O-GlcNAcase (OGA) inhibitor. In conclusion, EMPA attenuated ventricular arrhythmia inducibility by normalizing the intracellular Ca2+ handling, and we speculated that this effect was, at least partly, due to the inhibition of O-GlcNAcylation via the suppression of glucose uptake into cardiomyocytes.NEW & NOTEWORTHY SGLT2is are known to improve cardiovascular outcomes regardless of the presence of diabetes and decrease traditional cardiovascular risk factors. We demonstrated, for the first time, that EMPA inhibited PVCs by normalizing Ca2+ handling in diabetic mice. Our data suggest that the effects of SGLT2is on calcium handling may occur because of suppression of O-GlcNAcylation through inhibition of glucose uptake and not because of NHE inhibition, as previously suggested.


Assuntos
Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Cardiomiopatias Diabéticas , Inibidores do Transportador 2 de Sódio-Glicose , Camundongos , Animais , Miócitos Cardíacos/metabolismo , Cardiomiopatias Diabéticas/tratamento farmacológico , Cardiomiopatias Diabéticas/etiologia , Cardiomiopatias Diabéticas/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Arritmias Cardíacas/tratamento farmacológico , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/prevenção & controle , Glucose/metabolismo , Cálcio/metabolismo
6.
Heart Rhythm ; 20(2): 261-271, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36270579

RESUMO

BACKGROUND: Mapping techniques to identify diseased myocardial substrate during ventricular tachycardia ablation procedures remain limited. OBJECTIVE: We hypothesized that tissue derivative of the voltage with respect to time (dV/dt), the slope of the unipolar ventricular electrogram registered by local ventricular activation, represents a unique parameter for identifying potential arrhythmogenic tissue in the ischemic scar border zone. METHODS: Using high-resolution electrical mapping, we examined dV/dt characteristics in the border zone of animals after chronic myocardial infarction (MI). RESULTS: Minimum dV/dt (dV/dtmin) in MI animals was less than that in control animals (-344.7 ± 68.7 in controls vs -174.2 ± 104.5 in MI; P < .001) and related to ventricular fibrosis. In MI animals, dV/dtmin values were divided into high (≤-200 µV/ms) and low (>-200 µV/ms) dV/dtmin. Low dV/dtmin regions harbored arrhythmogenic substrates that were characterized by (1) high responsiveness to sympathetic stimulation, (2) presence of late potentials, and (3) lower unipolar and bipolar voltage amplitudes. CONCLUSION: Our data indicate that dV/dtmin is a unique parameter for identifying arrhythmogenic myocardium and may add a useful metric to conventional mapping strategies.


Assuntos
Ablação por Cateter , Infarto do Miocárdio , Taquicardia Ventricular , Humanos , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/etiologia , Taquicardia Ventricular/cirurgia , Miocárdio , Ventrículos do Coração , Arritmias Cardíacas , Ablação por Cateter/métodos
7.
Elife ; 112022 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-36426848

RESUMO

Stellate ganglia within the intrathoracic cardiac control system receive and integrate central, peripheral, and cardiopulmonary information to produce postganglionic cardiac sympathetic inputs. Pathological anatomical and structural remodeling occurs within the neurons of the stellate ganglion (SG) in the setting of heart failure (HF). A large proportion of SG neurons function as interneurons whose networking capabilities are largely unknown. Current therapies are limited to targeting sympathetic activity at the cardiac level or surgical interventions such as stellectomy, to treat HF. Future therapies that target the SG will require understanding of their networking capabilities to modify any pathological remodeling. We observe SG networking by examining cofluctuation and specificity of SG networked activity to cardiac cycle phases. We investigate network processing of cardiopulmonary transduction by SG neuronal populations in porcine with chronic pacing-induced HF and control subjects during extended in-vivo extracellular microelectrode recordings. We find that information processing and cardiac control in chronic HF by the SG, relative to controls, exhibits: (i) more frequent, short-lived, high magnitude cofluctuations, (ii) greater variation in neural specificity to cardiac cycles, and (iii) neural network activity and cardiac control linkage that depends on disease state and cofluctuation magnitude.


Assuntos
Insuficiência Cardíaca , Gânglio Estrelado , Animais , Suínos , Gânglio Estrelado/fisiologia , Gânglio Estrelado/cirurgia , Benchmarking , Entropia , Coração
8.
Am J Physiol Heart Circ Physiol ; 323(5): H869-H878, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36149772

RESUMO

Atrial fibrillation (AF) is associated with electrical remodeling processes that promote a substrate for the maintenance of AF. Although the small-conductance Ca2+-activated K+ (SK) channel is a key factor in atrial electrical remodeling, the mechanism of its activation remains unclear. Regional nitric oxide (NO) production by neuronal nitric oxide synthase (nNOS) is involved in atrial electrical remodeling. In this study, atrial tachyarrhythmia (ATA) induction and optical mapping were performed on perfused rat hearts. nNOS is pharmacologically inhibited by S-methylthiocitrulline (SMTC). The influence of the SK channel was examined using a specific channel inhibitor, apamin (APA). Parameters such as action potential duration (APD), conduction velocity, and calcium transient (CaT) were evaluated using voltage and calcium optical mapping. The dominant frequency was examined in the analysis of AF dynamics. SMTC (100 nM) increased the inducibility of ATA and apamin (100 nM) mitigated nNOS inhibition-induced arrhythmogenicity. SMTC caused abbreviations and enhanced the spatial dispersion of APD, which was reversed by apamin. By contrast, conduction velocity and other parameters associated with CaT were not affected by SMTC or apamin administration. Apamin reduced the frequency of SMTC-induced ATA. In summary, nNOS inhibition abbreviates APD by modifying the SK channels. A specific SK channel blocker, apamin, mitigated APD abbreviation without alteration of CaT, implying an underlying mechanism of posttranslational modification of SK channels.NEW & NOTEWORTHY We demonstrated that pharmacological nNOS inhibition increased the atrial arrhythmia inducibility and a specific small-conductance Ca2+-activated K+ channel blocker, apamin, reversed the enhanced atrial arrhythmia inducibility. Apamin mitigated APD abbreviation without alteration of Ca2+ transient, implying an underlying mechanism of posttranslational modification of SK channels.


Assuntos
Fibrilação Atrial , Remodelamento Atrial , Animais , Apamina/farmacologia , Cálcio/metabolismo , Óxido Nítrico , Óxido Nítrico Sintase Tipo I , Ratos , Canais de Potássio Ativados por Cálcio de Condutância Baixa
9.
Heart Rhythm ; 19(10): 1725-1735, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35660475

RESUMO

BACKGROUND: An aberrant increase in the diastolic calcium concentration ([Ca2+]i) level is a hallmark of heart failure (HF) and the cause of delayed afterdepolarization and ventricular arrhythmia (VA). Although mitochondria play a role in regulating [Ca2+]i, whether they can compensate for the [Ca2+]i abnormality in ventricular myocytes is unknown. OBJECTIVE: The purpose of this study was to investigate whether enhanced Ca2+ uptake of mitochondria may compensate for an abnormal increase in the [Ca2+]i of ventricular myocytes in HF to effectively mitigate VA. METHODS: We used a HF mouse model in which myocardial infarction was induced by permanent left anterior descending coronary artery ligation. The mitochondrial Ca2+ uniporter was stimulated by kaempferol. Ca2+ dynamics and membrane potential were measured using an epifluorescence microscope, a confocal microscope, and the perforated patch-clamp technique. VA was induced in Langendorff-perfused hearts, and hemodynamic parameters were measured using a microtip transducer catheter. RESULTS: Protein expression of the mitochondrial Ca2+ uniporter, as assessed by its subunit expression, did not change between HF and sham mice. Treatment of cardiomyocytes with kaempferol, isolated from HF mice 28 days after coronary ligation, reduced the appearance of aberrant diastolic [Ca2+]i waves and sparks and spontaneous action potentials. Kaempferol effectively reduced VA occurring in Langendorff-perfused hearts. Intravenous administration of kaempferol did not markedly affect left ventricular hemodynamic parameters. CONCLUSION: The effects of kaempferol in HF of mice implied that mitochondria may have the potential to compensate for abnormal [Ca2+]i. Mechanisms involved in mitochondrial Ca2+ uptake may provide novel targets for treatment of HF-associated VA.


Assuntos
Cálcio , Insuficiência Cardíaca , Animais , Arritmias Cardíacas , Cálcio/metabolismo , Canais de Cálcio , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/etiologia , Quempferóis/metabolismo , Quempferóis/farmacologia , Camundongos , Miócitos Cardíacos/metabolismo
10.
J Cardiol ; 80(2): 167-171, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35365376

RESUMO

BACKGROUND: Electrical storms (ESs) in patients with structural heart disease (SHD) have been reported to be associated with a poor prognosis. However, the detailed cause of death and influence of implantable cardioverter defibrillator (ICD) therapy in ES patients have not been fully investigated. Therefore, we sought to explore the detailed clinical course after an ES and the impact of the ICD therapy in patients with SHDs. METHODS: We retrospectively analyzed 31 consecutive patients with ESs who had undergone an ICD implantation. ESs were defined as three or more ventricular arrhythmias within 24 h. RESULTS: During a mean follow up of 4.5 years, 13 patients died. Among them, cardiovascular death (CVD) was observed in 11/13 (85%), and the leading cause of the CVD was end-stage heart failure. A New York Heart Association class ≥III at the time of the ES occurrence (HR 6.51 95% CI 1.94-25.1, p = 0.003) and any shock therapy (HR 5.94 95% CI 1.06-112.2, p = 0.04) were associated with CVD. CONCLUSION: In the current single center study, the major cause of death in ES patients with SHDs was end-stage heart failure. Any shock therapy was associated with CVD. Arrhythmia management to avoid ICD shocks might reduce the mortality in ES patients.


Assuntos
Desfibriladores Implantáveis , Insuficiência Cardíaca , Taquicardia Ventricular , Desfibriladores Implantáveis/efeitos adversos , Humanos , Estudos Retrospectivos , Taquicardia Ventricular/etiologia , Taquicardia Ventricular/terapia , Fibrilação Ventricular/etiologia , Fibrilação Ventricular/terapia
12.
Heart Rhythm ; 18(10): 1745-1757, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34182169

RESUMO

BACKGROUND: Clinical trials for renal artery (RA) ablation have shown limited efficacy. OBJECTIVE: The purpose of this study was to investigate whether the aorticorenal ganglion (ARG) can be targeted for renal denervation. METHODS: Twenty-eight pigs were studied under isoflurane or alpha-chloralose to examine hemodynamic responses and catecholamine release in response to RA or ARG stimulation. To assess the efficacy of ARG ablation, we randomized 16 pigs to either sham, RA, or ARG ablation, followed by occlusion of the left anterior descending coronary artery (LAD). Hemodynamic responses, cardiac electrophysiological parameters, and arrhythmias/sudden cardiac death were assessed following LAD occlusion. Absent hemodynamic responses to stimulation confirmed ARG or RA ablation. In vivo stellate ganglion neural activity was recorded to assess cardiac sympathetic signaling. Cadaveric dissections were performed to localize the ARG in humans for comparison to swine. RESULTS: The ARG is a purely sympathetic ganglion with cholinergic inputs and pass-through sensory afferent fibers. Compared to RA stimulation, ARG stimulation yielded greater hemodynamic responses during alpha-chloralose anesthesia. However, neither site yielded significant responses under isoflurane. Radiofrequency ablation of the ARG eliminated responses to both RA and ARG stimulation, whereas RA ablation did not eliminate responses to ARG stimulation. Ablation of the ARG did not impact the kidneys or adrenal glands. Compared to control and RA ablation, ARG ablation was protective against ventricular arrhythmias and sudden death. Human and swine ARG are similarly located in the aorticorenal region. CONCLUSION: Our findings indicate that the ARG may be a novel target for renal neuromodulation. Further studies are warranted to validate these findings.


Assuntos
Arritmias Cardíacas/terapia , Pressão Sanguínea/fisiologia , Frequência Cardíaca/fisiologia , Rim/inervação , Gânglio Estrelado/cirurgia , Simpatectomia/métodos , Animais , Arritmias Cardíacas/fisiopatologia , Modelos Animais de Doenças , Feminino , Masculino , Gânglio Estrelado/fisiopatologia , Suínos
13.
Heart Rhythm ; 18(9): 1586-1595, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33845214

RESUMO

BACKGROUND: The mechanisms underlying premature ventricular contraction (PVC)-induced cardiomyopathy (PIC) remain unknown. Transient receptor potential vanilloid-1 (TRPV1) afferent fibers are implicated in the reflex processing of cardiac stress. OBJECTIVE: The purpose of this study was to determine whether cardiac TRPV1 afferent signaling promote PIC. METHODS: A PIC swine model (50% PVC burden) was created via an implanted pacemaker. We selectively depleted cardiac TRPV1 afferent fibers using percutaneous epicardial application of resiniferatoxin (RTX). Animals were randomized to PVC only (n = 11), PVC+RTX (n = 11), or control (n = 6). We examined early-stage (4 weeks after implantation; n = 5) and late-stage PIC (8 weeks after implantation; n = 6). At terminal experimentation, animals underwent echocardiography, serum sampling, and physiological and autonomic reflex testing. RESULTS: Depletion of cardiac TRPV1 afferents by RTX treatment was confirmed by absent sensory fibers and absent functional responses to TRPV1 activators. Left ventricular ejection fraction was worse in late-stage than early-stage PIC (P <.01). At 4 weeks (early stage), left ventricular ejection fraction was higher in PVC+RTX vs PVC animals (51.7% ± 1.6% vs 45.0% ± 2.1%; P = .030), whereas no significant difference between PVC and PVC+RTX was observed at 8 weeks (late stage). Histologic studies demonstrated reduced fibrosis in PVC+RTX vs PVC alone at 4 weeks (2.27% ± 0.14% vs 3.01% ± 0.21%; P = .020), suggesting that RTX mitigated profibrotic pathways induced by persistent PVCs. CONCLUSION: TRPV1 afferent depletion alleviates left ventricular dysfunction in early- but not late-stage PIC. This temporal effect suggests that multiple pathways promote PIC, of which TRPV1 afferents are a part.


Assuntos
Vias Aferentes/fisiopatologia , Cardiomiopatias , Coração/inervação , Transdução de Sinais , Canais de Cátion TRPV/agonistas , Complexos Ventriculares Prematuros , Animais , Cardiomiopatias/etiologia , Cardiomiopatias/patologia , Cardiomiopatias/fisiopatologia , Diterpenos/farmacologia , Ecocardiografia/métodos , Fibrose , Modelos Animais , Neurotoxinas/farmacologia , Volume Sistólico , Suínos , Função Ventricular Esquerda , Complexos Ventriculares Prematuros/complicações , Complexos Ventriculares Prematuros/fisiopatologia
14.
Am J Physiol Heart Circ Physiol ; 320(4): H1456-H1469, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33635168

RESUMO

Ventricular arrhythmia (VA) is the major cause of death in patients with left ventricular (LV) hypertrophy and/or acute ischemia. We hypothesized that apamin, a blocker of small-conductance Ca2+-activated K+ (SK) channels, alters Ca2+ handling and exhibits anti-arrhythmic effects in ventricular myocardium. Spontaneous hypertensive rats were used as a model of LV hypertrophy. A dual optical mapping of membrane potential (Vm) and intracellular calcium (Cai) was performed during global hypoxia (GH) on the Langendorff perfusion system. The majority of pacing-induced VAs during GH were initiated by triggered activities. Pretreatment of apamin (100 nmol/L) significantly inhibited the VA inducibility. Compared with SK channel blockers (apamin and NS8593), non-SK channel blockers (glibenclamide and 4-AP) did not exhibit anti-arrhythmic effects. Apamin prevented not only action potential duration (APD80) shortening (-18.7 [95% confidence interval, -35.2 to -6.05] ms vs. -2.75 [95% CI, -10.45 to 12.65] ms, P = 0.04) but also calcium transient duration (CaTD80) prolongation (14.52 [95% CI, 8.8-20.35] ms vs. 3.85 [95% CI, -3.3 to 12.1] ms, P < 0.01), thereby reducing CaTD80 - APD80, which denotes "Cai/Vm uncoupling" (33.22 [95% CI, 22-48.4] ms vs. 6.6 [95% CI, 0-14.85] ms, P < 0.01). The reduction of Cai/Vm uncoupling was attributable to less prolonged Ca2+ decay constant and suppression of diastolic Cai increase by apamin. The inhibition of VA inducibility and changes in APs/CaTs parameters caused by apamin was negated by the addition of ouabain, an inhibitor of Na+/K+ pump. Apamin attenuates APD shortening, Ca2+ handling abnormalities, and Cai/Vm uncoupling, leading to inhibition of VA occurrence in hypoxic hypertrophied hearts.NEW & NOTEWORTHY We demonstrated that hypoxia-induced ventricular arrhythmias were mainly initiated by Ca2+-loaded triggered activities in hypertrophied hearts. The blockades of small-conductance Ca2+-activated K+ channels, especially "apamin," showed anti-arrhythmic effects by alleviation of not only action potential duration shortening but also Ca2+ handling abnormalities, most notably the "Ca2+/voltage uncoupling."


Assuntos
Antiarrítmicos/farmacologia , Arritmias Cardíacas/prevenção & controle , Sinalização do Cálcio/efeitos dos fármacos , Cardiomegalia/tratamento farmacológico , Frequência Cardíaca/efeitos dos fármacos , Hipóxia/tratamento farmacológico , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio Ativados por Cálcio de Condutância Baixa/antagonistas & inibidores , 1-Naftilamina/análogos & derivados , 1-Naftilamina/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Apamina/farmacologia , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatologia , Estimulação Cardíaca Artificial , Cardiomegalia/complicações , Cardiomegalia/metabolismo , Cardiomegalia/fisiopatologia , Modelos Animais de Doenças , Hipóxia/complicações , Hipóxia/metabolismo , Hipóxia/fisiopatologia , Preparação de Coração Isolado , Masculino , Ratos Endogâmicos SHR , Canais de Potássio Ativados por Cálcio de Condutância Baixa/metabolismo , Fatores de Tempo
15.
Int Heart J ; 61(6): 1150-1156, 2020 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-33191344

RESUMO

Recurrence of atrial tachyarrhythmias (ATA) following catheter ablation for atrial fibrillation (AF) is often associated with the recovery of conduction into previously isolated pulmonary veins (PVs). Little evidence concerning repeat PV isolation (PVI) and non-PV ATA ablation has been reported. This study aimed to explore the clinical outcome of recurrent ATA ablation after PVI and the difference between patients with and without non-PV ATA.A total of 49 patients without structural heart diseases who received catheter ablation for recurrent AF between January 2014 and December 2018 were recruited (prior ablation with PVI only 71.4% and PVI with cavotricuspid isthmus line ablation 28.6%). Patients were divided into two groups according to the presence or absence of non-PV ATA.Most patients (53.1%) experienced very late recurrence with a median duration of 15 months. A total of 15 patients had non-PV ATA and received non-PV ATA ablation whereas 34 patients received only repeat PVI for reconnected PVs. A higher pulmonary arterial systolic pressure (PASP) was associated with non-PV ATA (odds ratio: 1.161; 95% confidence interval: 1.021-1.321; P = 0.023). During 4.7 ± 1 months, 4/15 (26.7%) and 1/34 (2.9%) patients with and without non-PV ATA, respectively, had ATA recurrence (P = 0.011). The cumulative incidence of ATA recurrence after repeat ablation was significantly lower in patients without non-PV ATA (P = 0.013).In our study, a high PASP was associated with non-PV ATA in patients with recurrent AF. Repeat PVI had a high rate of maintenance of sinus rhythm in patients without non-PV ATA.


Assuntos
Pressão Arterial , Fibrilação Atrial/cirurgia , Ablação por Cateter , Artéria Pulmonar/fisiopatologia , Veias Pulmonares/cirurgia , Taquicardia Atrial Ectópica/epidemiologia , Idoso , Fibrilação Atrial/epidemiologia , Flutter Atrial , Ecocardiografia , Feminino , Humanos , Incidência , Modelos Logísticos , Masculino , Recidiva , Fatores de Risco , Fatores Sexuais
16.
Pacing Clin Electrophysiol ; 43(10): 1086-1095, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32735041

RESUMO

AIMS: Nonsustained ventricular tachycardia (NSVT) occurs frequently in patients with dilated cardiomyopathy (DCM), especially in high-risk patients. The role of rapid-rate NSVT (RR-NSVT) documented by an implantable cardioverter-defibrillator (ICD) in DCM patients has not been fully explored. This study aimed to determine the relationship between RR-NSVT and the occurrence of ventricular tachyarrhythmias (VTAs) in DCM patients with ICD. METHODS: From December 2000 to December 2017, 136 DCM patients received ICD or cardiac resynchronization therapy defibrillator (CRT-D) implantation for primary or secondary prevention of VTAs. Based on the occurrence of documented RR-NSVT, patients were classified into RR-NSVT (-) or RR-NSVT (+) groups. RESULT: During the median follow-up of 4.5 years, 50.0% (68/136) patients experienced ≥1 episode, and 25.0% (34/136) patients experienced ≥3 episodes of RR-NSVT. Event-free survival for VTAs was significantly higher in the RR-NSVT (-) group, whereas those for heart failure admission and cardiovascular mortality were comparable between groups. In the multivariate Cox regression analysis, any RR-NSVT showed a positive association with the occurrence of VTAs (hazard ratio: 5.087; 95% confidence interval: 2.374-10.900; P < .001). In RR-NSVT (+) patients, a cluster (≥3 times/6 months) and frequent pattern (≥3 runs/day) of RR-NSVT were observed in 42.6% (29/68) and 30.9% (21/68) patients, respectively, who showed further increased incidence of VTAs. CONCLUSION: In DCM patients with ICD/CRT-D, 50.0% patients experienced at least one episode of RR-NSVT. RR-NSVT documentation showed a positive association with subsequent occurrence of VTAs, suggesting the importance of constructive arrhythmia management for patients with RR-NSVT.


Assuntos
Cardiomiopatia Dilatada/complicações , Desfibriladores Implantáveis , Taquicardia Ventricular/etiologia , Taquicardia Ventricular/prevenção & controle , Cardiomiopatia Dilatada/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Taquicardia Ventricular/fisiopatologia
18.
Intern Med ; 59(17): 2155-2160, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32493855

RESUMO

Epirubicin-based chemotherapy carries a risk of inducing heart failure, although the frequency is rare. Bevacizumab, an anti-vascular endothelial growth factor monoclonal antibody, has recently been widely used in patients with recurrent breast cancer as a first-line chemotherapeutic agent. Heart failure or arterial thromboembolism has been reported as a rare cardiovascular complication of bevacizumab. We herein report a breast cancer patient with reversible cancer therapeutics-related cardiac dysfunction associated with bevacizumab and epirubicin complicating intracardiac thrombi in the left atrium and left ventricle. This case underscores the importance of tailored medical planning according to the individual status in patients receiving anti-cancer therapies.


Assuntos
Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Bevacizumab/efeitos adversos , Neoplasias da Mama/tratamento farmacológico , Epirubicina/efeitos adversos , Insuficiência Cardíaca/induzido quimicamente , Insuficiência Cardíaca/tratamento farmacológico , Antagonistas Adrenérgicos beta/uso terapêutico , Idoso , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Bevacizumab/uso terapêutico , Epirubicina/uso terapêutico , Feminino , Insuficiência Cardíaca/fisiopatologia , Humanos , Resultado do Tratamento
19.
Circ J ; 84(3): 397-403, 2020 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-32009066

RESUMO

BACKGROUND: Atrial fibrillation (AF) is an important prognostic determinant in heart failure (HF) with preserved ejection fraction (HFpEF). However, it is unclear which HFpEF phenotypes are affected by AF in terms of long-term clinical outcomes because HFpEF is a heterogeneous syndrome with comorbidities such as coronary artery disease (CAD). In this study we determined the differential prognostic significance of AF in HFpEF patients according to CAD status.Methods and Results:Data for 408 hospitalized HFpEF patients enrolled in the Japanese Heart Failure Syndrome with Preserved Ejection Fraction Nationwide Multicenter Registry were analyzed. Patients were divided into 4 groups according to the presence of AF and CAD. The primary outcome was the composite of all-cause death and HF rehospitalization. The incidence of adverse events was higher in the AF-non-CAD than non-AF-non-CAD group (P=0.004). On multivariable Cox regression analysis with prespecified confounders, AF-non-CAD was significantly associated with an increased risk of adverse events than non-AF-non-CAD (adjusted HR, 1.91; 95% CI: 1.02-3.92) regardless of the type of AF. In contrast, risk was comparable between the AF-CAD and non-AF-CAD groups (adjusted HR, 1.24; 95% CI: 0.64-2.47). CONCLUSIONS: In HFpEF patients without CAD, AF was independently related to adverse events, indicating that intensive management of AF would have more beneficial effects particularly in HFpEF patients without CAD.


Assuntos
Fibrilação Atrial/epidemiologia , Doença da Artéria Coronariana/epidemiologia , Insuficiência Cardíaca/epidemiologia , Admissão do Paciente , Idoso , Idoso de 80 Anos ou mais , Fibrilação Atrial/mortalidade , Fibrilação Atrial/fisiopatologia , Fibrilação Atrial/terapia , Doença da Artéria Coronariana/mortalidade , Doença da Artéria Coronariana/fisiopatologia , Doença da Artéria Coronariana/terapia , Feminino , Insuficiência Cardíaca/mortalidade , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/terapia , Frequência Cardíaca , Humanos , Incidência , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Readmissão do Paciente , Prognóstico , Sistema de Registros , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Volume Sistólico , Fatores de Tempo , Função Ventricular Esquerda
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