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1.
JACC Clin Electrophysiol ; 8(6): 795-799, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35738857

RESUMO

Thirty-eight patients had assessment of pulmonary vein occlusion with the dielectric mapping system and injection of saline as an alternative to contrast. Contrast injection was required to ascertain pulmonary vein occlusion in 31.6% (12 of 38) of subjects and 17.4% (27 of 155) of veins. No contrast was required in the last 13 subjects. In this single center study, a novel mapping-guided cryoablation approach appeared to minimize the use of contrast in pulmonary vein isolation for the treatment of atrial fibrillation.


Assuntos
Fibrilação Atrial , Criocirurgia , Veias Pulmonares , Pneumopatia Veno-Oclusiva , Fibrilação Atrial/cirurgia , Criocirurgia/efeitos adversos , Estudos de Viabilidade , Humanos , Veias Pulmonares/diagnóstico por imagem , Veias Pulmonares/cirurgia , Pneumopatia Veno-Oclusiva/cirurgia , Resultado do Tratamento
2.
J Cardiovasc Electrophysiol ; 32(8): 2060-2068, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34223691

RESUMO

BACKGROUND: Local impedance (LI) drop measured with microfidelity electrodes embedded in the tip of an ablation catheter accurately reflects tissue heating during radiofrequency (RF) ablation. Previous studies found 15-30 Ω LI drops created successful lesions, while more than 40 Ω drops were associated with steam pops. The objective of this study was to evaluate the safety and efficacy of LI-guided ablation using standard (30 W) and high-power (50 W) in a preclinical model. METHODS: RF lesions were created in explanted swine hearts (n = 6) to assess the feasibility of LI-guided ablation by targeting 10, 20, or 30 Ω (n = 20/group) drops. Subsequently, LI-guided ablation was evaluated in a chronic animal model (n = 8 Canines, 25-29 kg, 30/50 W). During the index procedure point-by-point intercaval line ablation and left inferior pulmonary vein (PV) isolation were performed. RF duration was at the operators' discretion but discontinued early if a 15-30 Ω drop was achieved. Operators attempted to avoid LI drops of more than 40 Ω. At 1-month, durable conduction block was evaluated with electroanatomic mapping followed by necropsy and histopathology. RESULTS: In explanted tissue, terminating ablation at 10, 20, or 30 Ω LI drops created statistically larger lesions (p < .05; 1.8 [1.6-2.4] mm, 3.3 [3.0-3.7] mm; 4.9 [4.3-5.5] mm). LI-guided high-power ablation in vivo significantly reduced RF duration per application compared to standard-power (p < .05; intercaval: 8.9 ± 5.2 vs. 18.1 ± 11.0 s, PV: 9.6 ± 5.4 vs. 23.2 ± 10.3 s). LI drops of 15-40 Ω were more readily achievable for high-power (90.1%, 318/353) than standard-power (71.7%, 243/339). All intercaval lines and PV isolations were durable (16/16) at 1-month. Necropsy revealed no major collateral injury to the pericardium, phrenic nerve, esophagus, or lungs. There was no pericardial effusion, stroke, tamponade, or PV stenosis. Vagal nerve injury was found in two 30 W animals after using 19.7 ± 13.9 and 19.5 ± 11.8 s RF applications. CONCLUSION: LI-guided ablation was found to be safe and efficacious in a chronic animal model. High-power ablation more readily achieved more than 15 Ω drops, reduced RF duration compared with standard-power, and had no major RF collateral injury.


Assuntos
Ablação por Cateter , Veias Pulmonares , Animais , Arritmias Cardíacas , Ablação por Cateter/efeitos adversos , Modelos Animais de Doenças , Cães , Impedância Elétrica , Veias Pulmonares/cirurgia , Suínos
3.
Europace ; 23(8): 1237-1243, 2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-33729470

RESUMO

AIMS: Cryoballoon pulmonary vein isolation (PVI) is a safe and effective treatment for atrial fibrillation (AF). Current limitations include incomplete vein occlusion due to balloon rigidity and inconsistent electrogram recording, which impairs identification of isolation. We aimed to evaluate the acute safety and performance of a novel cryoballoon system. METHODS AND RESULTS: The system includes a steerable sheath, mapping catheter, and a balloon that maintains uniform inflation pressure and size following initiation of ablation. Protocol-directed cryoablation was delivered for 180 s for isolation documented in ≤60 s, otherwise freeze duration was 240 s. Primary endpoints were acute safety and vein isolation. Pulmonary vein isolation was confirmed at ≥30 min post-isolation. Data were compared across vein locations. Thirty patients with paroxysmal AF were enrolled at two centres and underwent PVI. Pulmonary vein isolation was achieved with cryoablation only in 100% of veins (120/120). Nadir temperature was -53.1 ± 5.3°C. The number of applications to achieve PVI was 1.4 ± 0.4 per vein. Of the 120 veins, 89 were isolated with a single cryothermal application (10/30 patients required only 4 total cryoablations). There were no procedural- or device-related serious adverse events at 30 days post-procedure. A subset (24/30) of patients was followed for 1-year and 71% (17/24) remained free of atrial arrhythmias. Six patients with arrhythmia recurrence were remapped and three had durable PVI for all four veins. CONCLUSION: In this first human experience, the novel cryoballoon platform was safe, efficacious, and demonstrated a high proportion of successful single ablation isolation.


Assuntos
Fibrilação Atrial , Ablação por Cateter , Criocirurgia , Veias Pulmonares , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/cirurgia , Criocirurgia/efeitos adversos , Humanos , Veias Pulmonares/cirurgia , Recidiva , Resultado do Tratamento
5.
Circ Arrhythm Electrophysiol ; 11(4): e005831, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29618475

RESUMO

BACKGROUND: Coupling between the ablation catheter and myocardium is critical to resistively heat tissue with radiofrequency ablation. The objective of this study was to evaluate whether a novel local impedance (LI) measurement on an ablation catheter identifies catheter-tissue coupling and is predictive of lesion formation. METHODS AND RESULTS: LI was studied in explanted hearts (n=10 swine) and in vivo (n=10; 50-70 kg swine) using an investigational electroanatomic mapping system that measures impedance from an ablation catheter with mini-electrodes incorporated in the distal electrode (Rhythmia and IntellaNav MiFi OI, Boston Scientific). Explanted tissue was placed in a warmed (37 °C) saline bath mounted on a scale, and LI was measured 15 mm away from tissue to 5 mm of catheter-tissue compression at multiple catheter angles. Lesions were created with 31 and 50 W for 5 to 45 seconds (n=90). During in vivo evaluation of LI, measurements of myocardium (n=90) and blood pool (n=30) were guided by intracardiac ultrasound while operators were blinded to LI data. Lesions were created with 31 and 50 W for 45 seconds in the ventricles (n=72). LI of myocardium (119.7 Ω) was significantly greater than that of blood pool (67.6 Ω; P<0.01). Models that incorporate LI drop (ΔLI) to predict lesion size had better performance than models that incorporate force-time integral (R2=0.75 versus R2=0.54) and generator impedance drop (R2=0.82 versus R2=0.58). Steam pops displayed a significantly higher starting LI and larger ΔLI compared with successful radiofrequency applications (P<0.01). CONCLUSIONS: LI recorded from miniature electrodes provides a valuable measure of catheter-tissue coupling, and ΔLI is predictive of lesion formation during radiofrequency ablation.


Assuntos
Cateteres Cardíacos , Ablação por Cateter/instrumentação , Ventrículos do Coração/patologia , Ventrículos do Coração/cirurgia , Microeletrodos , Miocárdio/patologia , Animais , Ablação por Cateter/efeitos adversos , Impedância Elétrica , Desenho de Equipamento , Feminino , Masculino , Modelos Animais , Vapor , Sus scrofa
6.
PLoS One ; 12(1): e0168886, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28045933

RESUMO

Although the clinical range of interventions for coronary arteries is about 2 to 5 mm, the range of diameters of peripheral vasculature is significantly larger (about 10 mm for human iliac artery). When the vessel diameter is increased, the spacing between excitation electrodes on a conductance sizing device must also increase to accommodate the greater range of vessel diameters. The increase in the excitation electrodes distance, however, causes higher parallel conductance or current losses outside of artery lumen. We have previously shown that the conductance catheter/guidewire excitation electrode distances affects the measurement accuracy for the peripheral artery lumen sizing. Here, we propose a simple solution that varies the detection electrode distances to compensate for parallel conductance losses. Computational models were constructed to simulate the conductance guidewire with various electrodes spacing combinations over a range of peripheral artery lumen diameters and surrounding tissue electrical conductivities. The results demonstrate that the measurement accuracy may be significantly improved by increased detection spacing. Specifically, an optimally configured detection/excitation spacing (i.e., 5-5-5 or an equidistant electrode interval with a detection-to-excitation spacing ratio of 0.3) was shown to accurately predict the lumen diameter (i.e., -10% < error < 10%) over a broad range of peripheral artery dimensions (4 mm < diameter < 10 mm). The computational results were substantiated with both ex-vivo and in-vivo measurements of peripheral arteries. The present results support the accuracy of the conductance technique for measurement of peripheral reference vessel diameter.


Assuntos
Vasos Sanguíneos/anatomia & histologia , Cateteres , Vasos Coronários/anatomia & histologia , Animais , Aterosclerose , Cateterismo/instrumentação , Simulação por Computador , Condutividade Elétrica , Eletrodos , Desenho de Equipamento , Humanos , Artéria Ilíaca , Masculino , Modelos Cardiovasculares , Modelos Teóricos , Doença Arterial Periférica/terapia , Reprodutibilidade dos Testes , Suínos
7.
EuroIntervention ; 12(12): 1534-1541, 2016 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-27998846

RESUMO

AIMS: Percutaneous structural heart therapies, such as mitral value repair, require site-specific transseptal access (TSA). This can be challenging for interventional cardiologists. We describe a TSA catheter (TSAC) that utilises suction for enhanced control and puncture accuracy. Here, we aim to evaluate the safety and efficacy of the device. METHODS AND RESULTS: Ex vivo interatrial septum preparations were dissected from swine (n=8) and diseased human hearts (n=6) to quantify TSAC suction and needle puncture force. TSAC suction was 6.5-fold greater than the opposing needle puncture force, and thus provides sufficient stabilisation for punctures. The safety and efficacy of TSAC was evaluated in a chronic mitral regurgitation swine model (n=10) and compared to a conventional TSA device. MR was induced by disrupting one to three mitral chordae tendineae, and the progression of heart disease was followed for three weeks. During device testing, procedure time and fluoroscopy exposure were not statistically different between devices. TSAC reduced septal displacement from 8.7±0.30 mm to 3.60±0.19 mm (p<0.05) and improved puncture accuracy 1.75-fold. CONCLUSIONS: TSAC provides controlled TSA and improves puncture accuracy, while maintaining procedure time and workflow. These findings provide a strong rationale for a first-in-man study to demonstrate the clinical utility of the device.


Assuntos
Septo Interatrial/cirurgia , Desenho de Equipamento , Septos Cardíacos/cirurgia , Punções , Sucção , Animais , Cateterismo Cardíaco/instrumentação , Ablação por Cateter/instrumentação , Feminino , Humanos , Masculino , Punções/métodos , Sucção/métodos , Suínos
8.
Cardiovasc Res ; 108(1): 188-96, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26209251

RESUMO

AIMS: The duration and morphology of the T wave predict risk for ventricular fibrillation. A transmural gradient in action potential duration (APD) in the ventricular wall has been suggested to underlie the T wave in humans. We hypothesize that the transmural gradient in APD compensates for the normal endocardium-to-epicardium activation sequence and synchronizes repolarization in the human ventricular wall. METHODS AND RESULTS: We made left ventricular wedge preparations from 10 human donor hearts and measured transmural activation and repolarization patterns by optical mapping, while simultaneously recording a pseudo-ECG. We also studied the relation between local timings of repolarization with the T wave in silico. During endocardial pacing (1 Hz), APD was longer at the subendocardium than at the subepicardium (360 ± 17 vs. 317 ± 20 ms, P < 0.05). The transmural activation time was 32 ± 4 ms and resulted in final repolarization of the subepicardium at 349 ± 18 ms. The overall transmural dispersion in repolarization time was smaller than that of APD. During epicardial pacing, the dispersion in repolarization time increased, whereas that of APD remained similar. The morphology of the T wave did not differ between endocardial and epicardial stimulation. Simulations explained the constant T wave morphology without transmural APD gradients. CONCLUSION: The intrinsic transmural difference in APD compensates for the normal cardiac activation sequence, resulting in more homogeneous repolarization of the left ventricular wall. Our data suggest that the transmural repolarization differences do not fully explain the genesis of the T wave.


Assuntos
Potenciais de Ação , Função Ventricular Esquerda , Adulto , Idoso , Criança , Eletrocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
9.
J Struct Biol ; 188(1): 55-60, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25160725

RESUMO

The ventricular human myocyte is spatially organized for optimal ATP and Ca(2+) delivery to sarcomeric myosin and ionic pumps during every excitation-contraction cycle. Comprehension of three-dimensional geometry of the tightly packed ultrastructure has been derived from discontinuous two-dimensional images, but has never been precisely reconstructed or analyzed in human myocardium. Using a focused ion beam scanning electron microscope, we created nanoscale resolution serial images to quantify the three-dimensional ultrastructure of a human left ventricular myocyte. Transverse tubules (t-tubule), lipid droplets, A-bands, and mitochondria occupy 1.8, 1.9, 10.8, and 27.9% of the myocyte volume, respectively. The complex t-tubule system has a small tortuosity (1.04±0.01), and is composed of long transverse segments with diameters of 317±24nm and short branches. Our data indicates that lipid droplets located well beneath the sarcolemma are proximal to t-tubules, where 59% (13 of 22) of lipid droplet centroids are within 0.50µm of a t-tubule. This spatial association could have an important implication in the development and treatment of heart failure because it connects two independently known pathophysiological alterations, a substrate switch from fatty acids to glucose and t-tubular derangement.


Assuntos
Ventrículos do Coração/ultraestrutura , Células Musculares/ultraestrutura , Miocárdio/ultraestrutura , Miócitos Cardíacos/ultraestrutura , Trifosfato de Adenosina/metabolismo , Cálcio/metabolismo , Ventrículos do Coração/metabolismo , Humanos , Imageamento Tridimensional , Gotículas Lipídicas/metabolismo , Gotículas Lipídicas/ultraestrutura , Microscopia Eletrônica de Varredura , Células Musculares/metabolismo , Miócitos Cardíacos/metabolismo , Sarcolema/ultraestrutura
10.
Prog Biophys Mol Biol ; 115(2-3): 244-51, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25106701

RESUMO

Advances in material science techniques and pioneering circuit designs have led to the development of electronic membranes that can form intimate contacts with biological tissues. In this review, we present the range of geometries, sensors, and actuators available for custom configurations of electronic membranes in cardiac applications. Additionally, we highlight the desirable mechanics achieved by such devices that allow the circuits and substrates to deform with the beating heart. These devices unlock opportunities to collect continuous data on the electrical, metabolic, and mechanical state of the heart as well as a platform on which to develop high definition therapeutics.


Assuntos
Mapeamento Potencial de Superfície Corporal/instrumentação , Desfibriladores Implantáveis , Eletrocardiografia/instrumentação , Eletrodos , Membranas Artificiais , Marca-Passo Artificial , Materiais Biocompatíveis/síntese química , Módulo de Elasticidade , Desenho de Equipamento , Análise de Falha de Equipamento
11.
Am J Physiol Heart Circ Physiol ; 307(8): H1178-86, 2014 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-25128175

RESUMO

Instability of the inner mitochondrial membrane potential (ΔΨm) has been implicated in electrical dysfunction, including arrhythmogenesis during ischemia-reperfusion. Monitoring ΔΨm has led to conflicting results, where depolarization has been reported as sporadic and as a propagating wave. The present study was designed to resolve the aforementioned difference and determine the unknown relationship between ΔΨm and electrophysiology. We developed a novel imaging modality for simultaneous optical mapping of ΔΨm and transmembrane potential (Vm). Optical mapping was performed using potentiometric dyes on preparations from 4 mouse hearts, 14 rabbit hearts, and 7 human hearts. Our data showed that during ischemia, ΔΨm depolarization is sporadic and changes asynchronously with electrophysiological changes. Spatially, ΔΨm depolarization was associated with action potential duration shortening but not conduction slowing. Analysis of focal activity indicated that ΔΨm is not different within the myocardium where the focus originates compared with normal ventricular tissue. Overall, our data suggest that during ischemia, mitochondria maintain their function at the expense of sarcolemmal electrophysiology, but ΔΨm depolarization does not have a direct association to ischemia-induced arrhythmias.


Assuntos
Potenciais de Ação , Potencial da Membrana Mitocondrial , Isquemia Miocárdica/metabolismo , Animais , Humanos , Camundongos , Mitocôndrias/metabolismo , Mitocôndrias/fisiologia , Isquemia Miocárdica/fisiopatologia , Imagem Óptica/métodos , Coelhos
12.
J Cell Sci ; 127(Pt 9): 2106-19, 2014 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-24569881

RESUMO

The copy number of membrane proteins at the cell surface is tightly regulated. Many ion channels and receptors present retrieval motifs to COPI vesicle coats and are retained in the early secretory pathway. In some cases, the interaction with COPI is prevented by binding to 14-3-3 proteins. However, the functional significance of this antagonism between COPI and 14-3-3 in terminally differentiated cells is unknown. Here, we show that ATP-sensitive K(+) (KATP) channels, which are composed of Kir6.2 and SUR1 subunits, are stalled in the Golgi complex of ventricular, but not atrial, cardiomyocytes. Upon sustained ß-adrenergic stimulation, which leads to activation of protein kinase A (PKA), SUR1-containing channels reach the plasma membrane of ventricular cells. We show that PKA-dependent phosphorylation of the C-terminus of Kir6.2 decreases binding to COPI and, thereby, silences the arginine-based retrieval signal. Thus, activation of the sympathetic nervous system releases this population of KATP channels from storage in the Golgi and, hence, might facilitate the adaptive response to metabolic challenges.


Assuntos
Canais KATP/metabolismo , Receptores de Sulfonilureias/metabolismo , Proteínas 14-3-3/metabolismo , Animais , Western Blotting , Células Cultivadas , Cromatografia de Afinidade , Eletrofisiologia , Técnica Indireta de Fluorescência para Anticorpo , Imunoprecipitação , Masculino , Camundongos , Camundongos Knockout , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Transporte Proteico/fisiologia
13.
Nat Commun ; 5: 3329, 2014 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-24569383

RESUMO

Means for high-density multiparametric physiological mapping and stimulation are critically important in both basic and clinical cardiology. Current conformal electronic systems are essentially 2D sheets, which cannot cover the full epicardial surface or maintain reliable contact for chronic use without sutures or adhesives. Here we create 3D elastic membranes shaped precisely to match the epicardium of the heart via the use of 3D printing, as a platform for deformable arrays of multifunctional sensors, electronic and optoelectronic components. Such integumentary devices completely envelop the heart, in a form-fitting manner, and possess inherent elasticity, providing a mechanically stable biotic/abiotic interface during normal cardiac cycles. Component examples range from actuators for electrical, thermal and optical stimulation, to sensors for pH, temperature and mechanical strain. The semiconductor materials include silicon, gallium arsenide and gallium nitride, co-integrated with metals, metal oxides and polymers, to provide these and other operational capabilities. Ex vivo physiological experiments demonstrate various functions and methodological possibilities for cardiac research and therapy.


Assuntos
Algoritmos , Coração/fisiologia , Membranas Artificiais , Modelos Cardiovasculares , Pericárdio/fisiologia , Animais , Elastômeros/química , Eletrocardiografia/instrumentação , Eletrocardiografia/métodos , Eletrodos , Técnicas Eletrofisiológicas Cardíacas/instrumentação , Técnicas Eletrofisiológicas Cardíacas/métodos , Mapeamento Epicárdico/instrumentação , Mapeamento Epicárdico/métodos , Coração/anatomia & histologia , Sistema de Condução Cardíaco/fisiologia , Concentração de Íons de Hidrogênio , Imageamento Tridimensional , Técnicas In Vitro , Pericárdio/anatomia & histologia , Coelhos , Reprodutibilidade dos Testes , Semicondutores , Silicones/química , Temperatura
14.
Adv Healthc Mater ; 3(1): 59-68, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23868871

RESUMO

Stable pH is an established biomarker of health, relevant to all tissues of the body, including the heart. Clinical monitoring of pH in a practical manner, with high spatiotemporal resolution, is particularly difficult in organs such as the heart due to its soft mechanics, curvilinear geometry, heterogeneous surfaces, and continuous, complex rhythmic motion. The results presented here illustrate that advanced strategies in materials assembly and electrochemical growth can yield interconnected arrays of miniaturized IrOx pH sensors encapsulated in thin, low-modulus elastomers to yield conformal monitoring systems capable of noninvasive measurements on the surface of the beating heart. A thirty channel custom data acquisition system enables spatiotemporal pH mapping with a single potentiostat. In vitro testing reveals super-Nernstian sensitivity with excellent uniformity (69.9 ± 2.2 mV/pH), linear response to temperature (-1.6 mV °C(-1) ), and minimal influence of extracellular ions (<3.5 mV). Device examples include sensor arrays on balloon catheters and on skin-like stretchable membranes. Real-time measurement of pH on the surfaces of explanted rabbit hearts and a donated human heart during protocols of ischemia-reperfusion illustrate some of the capabilities. Envisioned applications range from devices for biological research, to surgical tools and long-term implants.


Assuntos
Eletrônica , Miocárdio/metabolismo , Animais , Cateterismo Cardíaco , Desenho de Equipamento , Humanos , Concentração de Íons de Hidrogênio , Íons/química , Íons/metabolismo , Isquemia/metabolismo , Isquemia/patologia , Microeletrodos , Miocárdio/química , Próteses e Implantes , Coelhos , Reperfusão , Temperatura
15.
J Am Coll Cardiol ; 63(9): 928-34, 2014 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-24361364

RESUMO

OBJECTIVES: The aim of this study was to evaluate the role of tyrosine kinase cellular-Src (c-Src) inhibition on connexin43 (Cx43) regulation in a mouse model of myocardial infarction (MI). BACKGROUND: MI is associated with decreased expression of Cx43, the principal gap junction protein responsible for propagating current in ventricles. Activated c-Src has been linked to Cx43 dysregulation. METHODS: MI was induced in 12-week-old mice by coronary artery occlusion. MI mice were treated with c-Src inhibitors (PP1 or AZD0530), PP3 (an inactive analogue of PP1), or saline. Treated hearts were compared to sham mice by echocardiography, optical mapping, telemetry electrocardiographic monitoring, and inducibility studies. Tissues were collected for immunoblotting, quantitative polymerase chain reaction, and immunohistochemistry. RESULTS: Active c-Src was elevated in PP3-treated MI mice compared to sham at the scar border (280%, p = 0.003) and distal ventricle (346%, p = 0.013). PP1 treatment restored active c-Src to sham levels at the scar border (86%, p = 0.95) and distal ventricle (94%, p = 1.0). PP1 raised Cx43 expression by 69% in the scar border (p = 0.048) and by 73% in the distal ventricle (p = 0.043) compared with PP3 mice. PP1-treated mice had restored conduction velocity at the scar border (PP3: 32 cm/s, PP1: 41 cm/s, p < 0.05) and lower arrhythmic inducibility (PP3: 71%, PP1: 35%, p < 0.05) than PP3 mice. PP1 did not change infarct size, electrocardiographic pattern, or cardiac function. AZD0530 treatment demonstrated restoration of Cx43 comparable to PP1. CONCLUSIONS: c-Src inhibition improved Cx43 levels and conduction velocity and lowered arrhythmia inducibility after MI, suggesting a new approach for arrhythmia reduction following MI.


Assuntos
Arritmias Cardíacas/metabolismo , Conexina 43/metabolismo , Regulação da Expressão Gênica , Infarto do Miocárdio/metabolismo , Quinases da Família src/antagonistas & inibidores , Animais , Arritmias Cardíacas/fisiopatologia , Benzodioxóis/farmacologia , Proteína Tirosina Quinase CSK , Morte Súbita , Ecocardiografia , Inibidores Enzimáticos/farmacologia , Junções Comunicantes/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/fisiopatologia , Proteína Fosfatase 1/metabolismo , Quinazolinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo
16.
Am J Physiol Heart Circ Physiol ; 305(11): H1569-73, 2013 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-24043254

RESUMO

Since its inception in 19th-century Germany, the physiology laboratory has been a complex and expensive research enterprise involving experts in various fields of science and engineering. Physiology research has been critically dependent on cutting-edge technological support of mechanical, electrical, optical, and more recently computer engineers. Evolution of modern experimental equipment is constrained by lack of direct communication between the physiological community and industry producing this equipment. Fortunately, recent advances in open source technologies, including three-dimensional printing, open source hardware and software, present an exciting opportunity to bring the design and development of research instrumentation to the end user, i.e., life scientists. Here we provide an overview on how to develop customized, cost-effective experimental equipment for physiology laboratories.


Assuntos
Desenho Assistido por Computador , Coração/anatomia & histologia , Imageamento Tridimensional , Laboratórios , Fisiologia/métodos , Impressão/métodos , Animais , Desenho de Equipamento , Humanos , Fisiologia/instrumentação , Impressão/instrumentação , Especificidade da Espécie
17.
J Mol Cell Cardiol ; 54: 25-34, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23123323

RESUMO

Cardiomyopathy is associated with cardiac Na(+) channel downregulation that may contribute to arrhythmias. Previously, we have shown that elevated intracellular NADH causes a decrease in cardiac Na(+) current (I(Na)) signaled by an increase in mitochondrial reactive oxygen species (ROS). In this study, we tested whether the NADH-mitochondria ROS pathway was involved in the reduction of I(Na) in a nonischemic cardiomyopathic model and correlated the findings with myopathic human hearts. Nonischemic cardiomyopathy was induced in C57BL/6 mice by hypertension after unilateral nephrectomy, deoxycorticosterone acetate (DOCA) pellet implantation, and salt water substitution. Sham operated mice were used as controls. After six weeks, heart tissue and ventricular myocytes isolated from mice were utilized for whole cell patch clamp recording, NADH/NAD(+) level measurements, and mitochondrial ROS monitoring with confocal microscopy. Human explanted hearts were studied using optical mapping. Compared to the sham mice, the arterial blood pressure was higher, the left ventricular volume was significantly enlarged (104.7±3.9 vs. 87.9±6.1 µL, P<0.05), and the ejection fraction was reduced (37.1±1.8% vs. 49.4±3.7%, P<0.05) in DOCA mice. Both the whole cell and cytosolic NADH level were increased (279±70% and 123±2% of sham, respectively, P<0.01), I(Na) was decreased (60±10% of sham, P<0.01), and mitochondrial ROS overproduction was observed (2.9±0.3-fold of sham, P<0.01) in heart tissue and myocytes of myopathic mice vs. sham. Treatment of myocytes with NAD(+) (500 µM), mitoTEMPO (10 µM), chelerythrine (50 µM), or forskolin (5 µM) restored I(Na) back to the level of sham. Injection of NAD(+) (100mg/kg) or mitoTEMPO (0.7 mg/kg) twice (at 24h and 1h before myocyte isolation) to animals also restored I(Na). All treatments simultaneously reduced mitochondrial ROS levels to that of controls. CD38 was found to transduce the extracellular NAD(+) signal. Correlating with the mouse model, failing human hearts showed a reduction in conduction velocity that improved with NAD(+). Nonischemic cardiomyopathy was associated with elevated NADH level, PKC activation, mitochondrial ROS overproduction, and a concomitant decrease in I(Na). Reducing mitochondrial ROS by application of NAD(+), mitoTEMPO, PKC inhibitors, or PKA activators, restored I(Na). NAD(+) improved conduction velocity in human myopathic hearts.


Assuntos
Cardiomiopatias/metabolismo , Mitocôndrias Cardíacas/fisiologia , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , ADP-Ribosil Ciclase 1/metabolismo , Potenciais de Ação/efeitos dos fármacos , Animais , Benzofenantridinas/farmacologia , Colforsina/farmacologia , Regulação para Baixo , Sistema de Condução Cardíaco/efeitos dos fármacos , Sistema de Condução Cardíaco/fisiopatologia , Humanos , Técnicas In Vitro , Glicoproteínas de Membrana/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/fisiologia , NAD/metabolismo , NAD/farmacologia , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Compostos Organofosforados/farmacologia , Estresse Oxidativo , Técnicas de Patch-Clamp , Piperidinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo
18.
J Biol Chem ; 287(46): 38901-12, 2012 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-23019328

RESUMO

Sarcolemmal CD36 facilitates myocardial fatty acid (FA) uptake, which is markedly reduced in CD36-deficient rodents and humans. CD36 also mediates signal transduction events involving a number of cellular pathways. In taste cells and macrophages, CD36 signaling was recently shown to regulate store-responsive Ca(2+) flux and activation of Ca(2+)-dependent phospholipases A(2) that cycle polyunsaturated FA into phospholipids. It is unknown whether CD36 deficiency influences myocardial Ca(2+) handling and phospholipid metabolism, which could compromise the heart, typically during stresses. Myocardial function was examined in fed or fasted (18-22 h) CD36(-/-) and WT mice. Echocardiography and telemetry identified conduction anomalies that were associated with the incidence of sudden death in fasted CD36(-/-) mice. No anomalies or death occurred in WT mice during fasting. Optical imaging of perfused hearts from fasted CD36(-/-) mice documented prolongation of Ca(2+) transients. Consistent with this, knockdown of CD36 in cardiomyocytes delayed clearance of cytosolic Ca(2+). Hearts of CD36(-/-) mice (fed or fasted) had 3-fold higher SERCA2a and 40% lower phospholamban levels. Phospholamban phosphorylation by protein kinase A (PKA) was enhanced after fasting reflecting increased PKA activity and cAMP levels in CD36(-/-) hearts. Abnormal Ca(2+) homeostasis in the CD36(-/-) myocardium associated with increased lysophospholipid content and a higher proportion of 22:6 FA in phospholipids suggests altered phospholipase A(2) activity and changes in membrane dynamics. The data support the role of CD36 in coordinating Ca(2+) homeostasis and lipid metabolism and the importance of this role during myocardial adaptation to fasting. Potential relevance of the findings to CD36-deficient humans would need to be determined.


Assuntos
Antígenos CD36/biossíntese , Cálcio/metabolismo , Miocárdio/metabolismo , Fosfolipídeos/metabolismo , Ração Animal , Animais , AMP Cíclico/metabolismo , Eletrocardiografia/métodos , Ácidos Graxos Insaturados/metabolismo , Homeostase , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fosfolipídeos/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Fatores de Tempo
19.
Am J Physiol Heart Circ Physiol ; 303(7): H753-65, 2012 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-22821993

RESUMO

Optical mapping has become an increasingly important tool to study cardiac electrophysiology in the past 20 years. Multiple methods are used to process and analyze cardiac optical mapping data, and no consensus currently exists regarding the optimum methods. The specific methods chosen to process optical mapping data are important because inappropriate data processing can affect the content of the data and thus alter the conclusions of the studies. Details of the different steps in processing optical imaging data, including image segmentation, spatial filtering, temporal filtering, and baseline drift removal, are provided in this review. We also provide descriptions of the common analyses performed on data obtained from cardiac optical imaging, including activation mapping, action potential duration mapping, repolarization mapping, conduction velocity measurements, and optical action potential upstroke analysis. Optical mapping is often used to study complex arrhythmias, and we also discuss dominant frequency analysis and phase mapping techniques used for the analysis of cardiac fibrillation.


Assuntos
Potenciais de Ação , Arritmias Cardíacas/diagnóstico , Corantes Fluorescentes , Sistema de Condução Cardíaco/fisiopatologia , Processamento de Sinais Assistido por Computador , Imagens com Corantes Sensíveis à Voltagem/métodos , Algoritmos , Animais , Arritmias Cardíacas/fisiopatologia , Humanos , Valor Preditivo dos Testes , Fatores de Tempo
20.
Circ Arrhythm Electrophysiol ; 5(2): 409-16, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22322367

RESUMO

BACKGROUND: High intensity focused ultrasound (HIFU) has been introduced for treatment of cardiac arrhythmias because it offers the ability to create rapid tissue modification in confined volumes without directly contacting the myocardium. In spite of the benefits of HIFU, a number of limitations have been reported, which hindered its clinical adoption. METHODS AND RESULTS: In this study, we used a multimodal approach to evaluate thermal and nonthermal effects of HIFU in cardiac ablation. We designed a computer controlled system capable of simultaneous fluorescence mapping and HIFU ablation. Using this system, linear lesions were created in isolated rabbit atria (n=6), and point lesions were created in the ventricles of whole-heart (n=6) preparations by applying HIFU at clinical doses (4-16 W). Additionally, we evaluate the gap size in ablation lines necessary for conduction in atrial preparations (n=4). The voltage sensitive dye di-4-ANEPPS was used to assess functional damage produced by HIFU. Optical coherence tomography and general histology were used to evaluate lesion extent. Conduction block was achieved in 1 (17%) of 6 atrial preparations with a single ablation line. Following 10 minutes of rest, 0 (0%) of 6 atrial preparations demonstrated sustained conduction block from a single ablation line. Tissue displacement of 1 to 3 mm was observed during HIFU application due to acoustic radiation force along the lesion line. Additionally, excessive acoustic pressure and high temperature from HIFU generated cavitation, causing macroscopic tissue damage. A minimum gap size of 1.5 mm was found to conduct electric activity. CONCLUSIONS: This study identified 3 potential mechanisms responsible for the failure of HIFU ablation in cardiac tissues. Both acoustic radiation force and acoustic cavitation, in conjunction with inconsistent thermal deposition, can increase the risk of lesion discontinuity and result in gap sizes that promote ablation failure.


Assuntos
Falha de Equipamento , Átrios do Coração/cirurgia , Ventrículos do Coração/cirurgia , Ablação por Ultrassom Focalizado de Alta Intensidade/instrumentação , Ablação por Ultrassom Focalizado de Alta Intensidade/métodos , Acústica , Animais , Temperatura Alta , Fenômenos Mecânicos , Modelos Animais , Coelhos
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