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1.
Eur Heart J ; 40(26): 2142-2151, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31098611

RESUMO

AIMS: We aimed to evaluate the frequency, clinical features, and prognostic implications of cardiac arrest (CA) in takotsubo syndrome (TTS). METHODS AND RESULTS: We reviewed the records of patients with CA and known heart rhythm from the International Takotsubo Registry. The main outcomes were 60-day and 5-year mortality. In addition, predictors of mortality and predictors of CA during the acute TTS phase were assessed. Of 2098 patients, 103 patients with CA and known heart rhythm during CA were included. Compared with patients without CA, CA patients were more likely to be younger, male, and have apical TTS, atrial fibrillation (AF), neurologic comorbidities, physical triggers, and longer corrected QT-interval and lower left ventricular ejection fraction on admission. In all, 57.1% of patients with CA at admission had ventricular fibrillation/tachycardia, while 73.7% of patients with CA in the acute phase had asystole/pulseless electrical activity. Patients with CA showed higher 60-day (40.3% vs. 4.0%, P < 0.001) and 5-year mortality (68.9% vs. 16.7%, P < 0.001) than patients without CA. T-wave inversion and intracranial haemorrhage were independently associated with higher 60-day mortality after CA, whereas female gender was associated with lower 60-day mortality. In the acute phase, CA occurred less frequently in females and more frequently in patients with AF, ST-segment elevation, and higher C-reactive protein on admission. CONCLUSIONS: Cardiac arrest is relatively frequent in TTS and is associated with higher short- and long-term mortality. Clinical and electrocardiographic parameters independently predicted mortality after CA.

2.
J Mol Cell Cardiol ; 131: 53-65, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31005484

RESUMO

AIMS: Atrial contractile dysfunction is associated with increased mortality in heart failure (HF). We have shown previously that a metabolic syndrome-based model of HFpEF and a model of hypertensive heart disease (HHD) have impaired left atrial (LA) function in vivo (rat). In this study we postulate, that left atrial cardiomyocyte (CM) and cardiac fibroblast (CF) paracrine interaction related to the inositol 1,4,5-trisphosphate signalling cascade is pivotal for the manifestation of atrial mechanical dysfunction in HF and that quantitative atrial remodeling is highly disease-dependent. METHODS AND RESULTS: Differential remodeling was observed in HHD and HFpEF as indicated by an increase of atrial size in vivo (HFpEF), unchanged fibrosis (HHD and HFpEF) and a decrease of CM size (HHD). Baseline contractile performance of rat CM in vitro was enhanced in HFpEF. Upon treatment with conditioned medium from their respective stretched CF (CM-SF), CM (at 21 weeks) of WT showed increased Ca2+ transient (CaT) amplitudes related to the paracrine activity of the inotrope endothelin (ET-1) and inositol 1,4,5-trisphosphate induced Ca2+ release. Concentration of ET-1 was increased in CM-SF and atrial tissue from WT as compared to HHD and HFpEF. In HHD, CM-SF had no relevant effect on CaT kinetics. However, in HFpEF, CM-SF increased diastolic Ca2+ and slowed Ca2+ removal, potentially contributing to an in-vivo decompensation. During disease progression (i.e. at 27 weeks), HFpEF displayed dysfunctional excitation-contraction-coupling (ECC) due to lower sarcoplasmic-reticulum Ca2+ content unrelated to CF-CM interaction or ET-1, but associated with enhanced nuclear [Ca2+]. In human patients, tissue ET-1 was not related to the presence of arterial hypertension or obesity. CONCLUSIONS: Atrial remodeling is a complex entity that is highly disease and stage dependent. The activity of fibrosis related to paracrine interaction (e.g. ET-1) might contribute to in vitro and in vivo atrial dysfunction. However, during later stages of disease, ECC is impaired unrelated to CF.

4.
J Vis Exp ; (137)2018 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-30102264

RESUMO

In this article, we describe an optimized, Langendorff-based procedure for the isolation of single-cell atrial cardiomyocytes (ACMs) from a rat model of metabolic syndrome (MetS)-related heart failure with preserved ejection fraction (HFpEF). The prevalence of MetS-related HFpEF is rising, and atrial cardiomyopathies associated with atrial remodeling and atrial fibrillation are clinically highly relevant as atrial remodeling is an independent predictor of mortality. Studies with isolated single-cell cardiomyocytes are frequently used to corroborate and complement in vivo findings. Circulatory vessel rarefication and interstitial tissue fibrosis pose a potentially limiting factor for the successful single-cell isolation of ACMs from animal models of this disease. We have addressed this issue by employing a device capable of manually regulating the intraluminal pressure of cardiac cavities during the isolation procedure, substantially increasing the yield of morphologically and functionally intact ACMs. The acquired cells can be used in a variety of different experiments, such as cell culture and functional Calcium imaging (i.e., excitation-contraction-coupling). We provide the researcher with a step-by-step protocol, a list of optimized solutions, thorough instructions to prepare the necessary equipment, and a comprehensive troubleshooting guide. While the initial implementation of the procedure might be rather difficult, a successful adaptation will allow the reader to perform state-of-the-art ACM isolations in a rat model of MetS-related HFpEF for a broad spectrum of experiments.


Assuntos
Insuficiência Cardíaca/fisiopatologia , Síndrome Metabólica/complicações , Miócitos Cardíacos/metabolismo , Volume Sistólico/fisiologia , Animais , Modelos Animais de Doenças , Humanos , Ratos
5.
J Am Coll Cardiol ; 72(8): 874-882, 2018 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-30115226

RESUMO

BACKGROUND: Prognosis of Takotsubo syndrome (TTS) remains controversial due to scarcity of available data. Additionally, the effect of the triggering factors remains elusive. OBJECTIVES: This study compared prognosis between TTS and acute coronary syndrome (ACS) patients and investigated short- and long-term outcomes in TTS based on different triggers. METHODS: Patients with TTS were enrolled from the International Takotsubo Registry. Long-term mortality of patients with TTS was compared to an age- and sex-matched cohort of patients with ACS. In addition, short- and long-term outcomes were compared between different groups according to triggering conditions. RESULTS: Overall, TTS patients had a comparable long-term mortality risk with ACS patients. Of 1,613 TTS patients, an emotional trigger was detected in 485 patients (30%). Of 630 patients (39%) related to physical triggers, 98 patients (6%) had acute neurologic disorders, while in the other 532 patients (33%), physical activities, medical conditions, or procedures were the triggering conditions. The remaining 498 patients (31%) had no identifiable trigger. TTS patients related to physical stress showed higher mortality rates than ACS patients during long-term follow-up, whereas patients related to emotional stress had better outcomes compared with ACS patients. CONCLUSIONS: Overall, TTS patients had long-term outcomes comparable to age- and sex-matched ACS patients. Also, we demonstrated that TTS can either be benign or a life-threating condition depending on the inciting stress factor. We propose a new classification based on triggers, which can serve as a clinical tool to predict short- and long-term outcomes of TTS. (International Takotsubo Registry [InterTAK Registry]; NCT01947621).

6.
Am J Physiol Heart Circ Physiol ; 315(3): H669-H680, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29727215

RESUMO

Experimental data indicate that stimulation of the nitric oxide-soluble guanylate cyclase(sGC)-cGMP-PKG pathway can increase left ventricular (LV) capacitance via phosphorylation of the myofilamental protein titin. We aimed to test whether acute pharmacological sGC stimulation with BAY 41-8543 would increase LV capacitance via titin phosphorylation in healthy and deoxycorticosteroneacetate (DOCA)-induced hypertensive pigs. Nine healthy Landrace pigs and 7 pigs with DOCA-induced hypertension and LV concentric hypertrophy were acutely instrumented to measure LV end-diastolic pressure-volume relationships (EDPVRs) at baseline and during intravenous infusion of BAY 41-8543 (1 and 3 µg·kg-1·min-1 for 30 min, respectively). Separately, in seven healthy and six DOCA pigs, transmural LV biopsies were harvested from the beating heart to measure titin phosphorylation during BAY 41-8543 infusion. LV EDPVRs before and during BAY 41-8543 infusion were superimposable in both healthy and DOCA-treated pigs, whereas mean aortic pressure decreased by 20-30 mmHg in both groups. Myocardial titin phosphorylation was unchanged in healthy pigs, but total and site-specific (Pro-Glu-Val-Lys and N2-Bus domains) titin phosphorylation was increased in DOCA-treated pigs. Bicoronary nitroglycerin infusion in healthy pigs ( n = 5) induced a rightward shift of the LV EDPVR, demonstrating the responsiveness of the pathway in this model. Acute systemic sGC stimulation with the sGC stimulator BAY 41-8543 did not recruit an LV preload reserve in both healthy and hypertrophied LV porcine myocardium, although it increased titin phosphorylation in the latter group. Thus, increased titin phosphorylation is not indicative of increased in vivo LV capacitance. NEW & NOTEWORTHY We demonstrate that acute pharmacological stimulation of soluble guanylate cyclase does not increase left ventricular compliance in normal and hypertrophied porcine hearts. Effects of long-term soluble guanylate cyclase stimulation with oral compounds in disease conditions associated with lowered myocardial cGMP levels, i.e., heart failure with preserved ejection fraction, remain to be investigated.

7.
Heart Rhythm ; 15(9): 1328-1336, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29803020

RESUMO

BACKGROUND: Arterial hypertension (HT) contributes to progression of atrial fibrillation (AF) via unknown mechanisms. OBJECTIVE: We aimed to characterize electrical and structural changes accounting for increased AF stability in a large animal model of rapid atrial pacing (RAP)-induced AF combined with desoxycorticosterone acetate (DOCA)-induced HT. METHODS: Eighteen pigs were instrumented with right atrial endocardial pacemaker leads and custom-made pacemakers to induce AF by continuous RAP (600 beats/min). DOCA pellets were subcutaneously implanted in a subgroup of 9 animals (AF+HT group); the other 9 animals served as controls (AF group). Final experiments included electrophysiology studies, endocardial electroanatomic mapping, and high-density mapping with epicardial multielectrode arrays. In addition, 3-dimensional computational modeling was performed. RESULTS: DOCA implantation led to secondary HT (median [interquartile range] aortic pressure 109.9 [100-137] mm Hg in AF+HT vs 82.2 [79-96] mm Hg in AF; P < .05), increased AF stability (55.6% vs 12.5% of animals with AF episodes lasting >1 hour; P < .05), concentric left ventricular hypertrophy, atrial dilatation (119 ± 31 cm2 in AF+HT vs 78 ± 23 cm2 in AF; P < .05), and fibrosis. Collagen accumulation in the AF+HT group was mainly found in non-intermyocyte areas (1.62 ± 0.38 cm3 in AF+HT vs 0.96 ± 0.3 cm3 in AF; P < .05). Left and right atrial effective refractory periods, action potential durations, endo- and epicardial conduction velocities, and measures of AF complexity were comparable between the 2 groups. A 3-dimensional computational model confirmed an increase in AF stability observed in the in vivo experiments associated with increased atrial size. CONCLUSION: In this model of secondary HT, higher AF stability after 2 weeks of RAP is mainly driven by atrial dilatation.

8.
Artigo em Inglês | MEDLINE | ID: mdl-29663449

RESUMO

OBJECTIVE: Application of therapeutic mild hypothermia in patients after resuscitation, often accompanied by myocardial infarction, cardiogenic shock, and systemic inflammation may impact on cardiac rhythm. We therefore tested susceptibility to atrial arrhythmias during hyperthermia (HT, 40.5°C), normothermia (NT, 38.0°C), and mild hypothermia (MH, 33.0°C). METHODS: Nine healthy, anesthetized closed-chest landrace pigs were instrumented with a quadripolar stimulation catheter in the high right atrium and a decapolar catheter in the coronary sinus. Twelve-lead surface electrograms were recorded and core body temperature was altered to HT, NT, and MH using external warming or intravascular cooling. Repetitive measurements of effective atrial refractory period (AERP), atrial fibrillation (AF) inducibility, and electrocardiogram (ECG) parameters at different heart rates were performed. RESULTS: During MH, AERP was significantly longer while the inducibility of AF was significantly higher compared to NT and HT (median [range]: HT 18 (0, 80)%; NT 25 (0, 80)%; MH 68 (0, 100)%; P < 0.05 MH vs NT+HT). Mean AF duration did not differ between groups. Arterial potassium levels decreased with falling temperatures (HT: 4.2 ± 0.1 mmol/L; NT: 4.0 ± 0.2 mmol/L; MH: 3.5 ± 0.1 mmol/L; P < 0.001). Surface ECGs during MH showed reduced spontaneous heart rate (HT: 99 ± 13 beats/min; NT: 87 ± 15 beats/min; MH: 66 ± 10 beats/min; P < 0.05), increased PQ, stim-Q, and QT intervals (P < 0.01) but no change in QRS duration or time from peak to end of the T wave interval. CONCLUSION: Our data imply that MH represents an arrhythmic substrate rendering the atria more susceptible to AF although conduction times as well as refractory periods are increased. Further investigations on potential electrophysiological limits of therapeutic cooling in patients are required.

9.
J Mol Cell Cardiol ; 115: 10-19, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29289652

RESUMO

Heart failure (HF) with preserved ejection fraction (HFpEF) is present in about 50% of HF patients. Atrial remodeling is common in HFpEF and associated with increased mortality. We postulate that atrial remodeling is associated with atrial dysfunction in vivo related to alterations in cardiomyocyte Calcium (Ca) signaling and remodeling. We examined atrial function in vivo and Ca transients (CaT) (Fluo4-AM, field stim) in atrial cardiomyocytes of ZSF-1 rats without (Ln; lean hypertensive) and with metabolic syndrome (Ob; obese, hypertensive, diabetic) and HFpEF. RESULTS: At 21weeks Ln showed an increased left ventricular (LV) mass and left ventricular end-diastolic pressure (LVEDP), but unchanged left atrial (LA) size and preserved atrial ejection fraction vs. wild-type (WT). CaT amplitude in atrial cardiomyocytes was increased in Ln (2.9±0.2 vs. 2.3±0.2F/F0 in WT; n=22 cells/group; p<0.05). Studying subcellular Ca release in more detail, we found that local central cytosolic CaT amplitude was increased, while subsarcolemmal CaT amplitudes remained unchanged. Moreover, Sarcoplasmic reticulum (SR) Ca content (caffeine) was preserved while Ca spark frequency and tetracaine-dependent SR Ca leak were significantly increased in Ln. Ob mice developed a HFpEF phenotype in vivo, LA area was significantly increased and atrial in vivo function was impaired, despite increased atrial CaT amplitudes in vitro (2.8±0.2; p<0.05 vs. WT). Ob cells showed alterations of the tubular network possibly contributing to the observed phenotype. CaT kinetics as well as SR Ca in Ob were not significantly different from WT, but SR Ca leak remained increased. Angiotensin II (Ang II) reduced in vitro cytosolic CaT amplitudes and let to active nuclear Ca release in Ob but not in Ln or WT. SUMMARY: In hypertensive ZSF-1 rats, a possibly compensatory increase of cytosolic CaT amplitude and increased SR Ca leak precede atrial remodeling and HFpEF. Atrial remodeling in ZSF-1 HFpEF is associated with an altered tubular network in-vitro and atrial contractile dysfunction in vivo, indicating insufficient compensation. Atrial cardiomyocyte dysfunction in vitro is induced by the addition of angiotensin II.

10.
J Electrocardiol ; 49(2): 124-31, 2016 Mar-Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26803554

RESUMO

Mechanisms underlying atrial remodeling toward atrial fibrillation (AF) are incompletely understood. We induced AF in 16 pigs by 6weeks of rapid atrial pacing (RAP, 600bpm) using a custom-built, telemetrically controlled pacemaker. AF evolution was monitored three times per week telemetrically in unstressed, conscious animals. We established a dose-response relationship between RAP duration and occurrence of sustained AF >60minutes. Left atrial (LA) dilatation was present already at 2weeks of RAP. There was no evidence of left ventricular heart failure after 6weeks of RAP. As a proof-of-principle, arterial hypertension was induced in 5/16 animals by implanting desoxycorticosterone acetate (DOCA, an aldosterone-analog) subcutaneously to accelerate atrial remodeling. RAP+DOCA resulted in increased AF stability with earlier onset of sustained AF and accelerated anatomical atrial remodeling with more pronounced LA dilatation. This novel porcine model can serve to characterize effects of maladaptive stimuli or protective interventions specifically during early AF.


Assuntos
Fibrilação Atrial/diagnóstico , Fibrilação Atrial/fisiopatologia , Modelos Animais de Doenças , Marca-Passo Artificial , Próteses e Implantes , Telemetria/instrumentação , Animais , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Suínos , Telemetria/métodos
11.
Crit Care Med ; 44(3): e158-67, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26474110

RESUMO

OBJECTIVES: The results from the recent Targeted Temperature Management trial raised the question whether cooling or merely the avoidance of fever mediates better neurologic outcome in resuscitated patients. As temperature per se is a major determinant of cardiac function, we characterized the effects of hyperthermia (40.5°C), normothermia (38.0°C), and mild hypothermia (33.0°C) on left ventricular contractile function in healthy pigs and compared them with dobutamine infusion. DESIGN: Animal study. SETTING: Large animal facility, Medical University of Graz, Graz, Austria. SUBJECTS: Nine anesthetized and mechanically ventilated closed-chest Landrace pigs (67 ± 2 kg). INTERVENTIONS: Core body temperature was controlled using an intravascular device. At each temperature step, IV dobutamine was titrated to double maximum left ventricular dP/dt (1.8 ± 0.1 µg/kg/min at normothermia). Left ventricular pressure-volume relationships were assessed during short aortic occlusions. Left ventricular contractility was assessed by the calculated left ventricular end-systolic volume at an end-systolic left ventricular pressure of 100 mm Hg. MEASUREMENTS AND MAIN RESULTS: Heart rate (98 ± 4 vs 89 ± 4 vs 65 ± 2 beats/min; all p < 0.05) and cardiac output (6.7 ± 0.3 vs 6.1 ± 0.3 vs 4.4 ± 0.2 L/min) decreased with cooling from hyperthermia to normothermia and mild hypothermia, whereas left ventricular contractility increased (left ventricular end-systolic volume at a pressure of 100 mm Hg: 74 ± 5 mL at hyperthermia, 52 ± 4 mL at normothermia, and 41 ± 3 mL at mild hypothermia; all p < 0.05). The effect of cooling on left ventricular end-systolic volume at a pressure of 100 mm Hg (hyperthermia to normothermia: -28% ± 3% and normothermia to mild hypothermia: -20% ± 5%) was of comparable effect size as dobutamine at a given temperature (hyperthermia: -28% ± 4%, normothermia: -27% ± 6%, and mild hypothermia: -27% ± 9%). CONCLUSIONS: Cooling from hyperthermia to normothermia and from normothermia to mild hypothermia increased left ventricular contractility to a similar degree as a significant dose of dobutamine in the normal porcine heart. These data indicate that cooling can reduce the need for positive inotropes and that lower rather than higher temperatures are appropriate for the resuscitated failing heart.


Assuntos
Dobutamina/farmacologia , Hipertermia Induzida , Hipotermia Induzida , Contração Miocárdica/fisiologia , Função Ventricular Esquerda/fisiologia , Animais , Gasometria , Débito Cardíaco , Frequência Cardíaca/efeitos dos fármacos , Hipertermia Induzida/métodos , Hipotermia Induzida/métodos , Contração Miocárdica/efeitos dos fármacos , Volume Sistólico , Sus scrofa , Função Ventricular Esquerda/efeitos dos fármacos
12.
Am J Hypertens ; 29(7): 866-72, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26643687

RESUMO

BACKGROUND: Adherence to medication and lifestyle interventions are essential keys for the management of hypertension. In this respect, a structured educational program for hypertensive patients has got remarkable merits (herz.leben). In order to determine the isolated effect of participation in the educational program, neglecting the possible impact of more intense care, this prospective multicenter randomized controlled study was designed (NCT00453037). METHODS: A total of 256 patients in 13 centers were enrolled and randomly assigned to 2 groups (G). G-I (n = 137) underwent the educational program immediately (T-0), G-II (n = 119) after 6 months (T-6). Follow-up visits were done after 6 (T-6) and 12 (T-12) months. Primary endpoint was a difference in office blood pressure (BP) at T-6, when only G-I had undergone the educational program. RESULTS: Patients' baseline characteristics were comparable. At T-6, systolic office and home BP were significantly lower in G-I compared to G-II: office BP systolic 139 (134-150) mm Hg vs. 150 (135-165) mm Hg (P < 0.01); diastolic 80 (76-85) mm Hg vs. 84 (75-90) mm Hg (ns); home BP systolic 133 (130-140) mm Hg vs. 142 (132-150) mm Hg (P < 0.01); diastolic 80 (75-85) mm Hg vs. 80 (76-89) mm Hg (ns)). At T-12, when all patients had undergone the educational program differences in BP disappeared. CONCLUSION: The results of this multicenter randomized controlled study provide significant evidence for benefit by participation in a structured educational program. Positive effects seem to be mediated by better adherence and life style changes due to higher levels of information and patient empowerment. Therefore, educational strategies should be considered as standard of care for hypertensive patients.


Assuntos
Hipertensão Essencial/terapia , Educação de Pacientes como Assunto/métodos , Idoso , Gerenciamento Clínico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Avaliação de Programas e Projetos de Saúde
13.
Am J Physiol Heart Circ Physiol ; 309(9): H1407-18, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26342070

RESUMO

Heart failure with preserved ejection fraction (HFPEF) evolves with the accumulation of risk factors. Relevant animal models to identify potential therapeutic targets and to test novel therapies for HFPEF are missing. We induced hypertension and hyperlipidemia in landrace pigs (n = 8) by deoxycorticosteroneacetate (DOCA, 100 mg/kg, 90-day-release subcutaneous depot) and a Western diet (WD) containing high amounts of salt, fat, cholesterol, and sugar for 12 wk. Compared with weight-matched controls (n = 8), DOCA/WD-treated pigs showed left ventricular (LV) concentric hypertrophy and left atrial dilatation in the absence of significant changes in LV ejection fraction or symptoms of heart failure at rest. The LV end-diastolic pressure-volume relationship was markedly shifted leftward. During simultaneous right atrial pacing and dobutamine infusion, cardiac output reserve and LV peak inflow velocities were lower in DOCA/WD-treated pigs at higher LV end-diastolic pressures. In LV biopsies, we observed myocyte hypertrophy, a shift toward the stiffer titin isoform N2B, and reduced total titin phosphorylation. LV superoxide production was increased, in part attributable to nitric oxide synthase (NOS) uncoupling, whereas AKT and NOS isoform expression and phosphorylation were unchanged. In conclusion, we developed a large-animal model in which loss of LV capacitance was associated with a titin isoform shift and dysfunctional NOS, in the presence of preserved LV ejection fraction. Our findings identify potential targets for the treatment of HFPEF in a relevant large-animal model.


Assuntos
Cardiomiopatias/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Hipertensão/complicações , Hipertrofia Ventricular Esquerda/fisiopatologia , Miócitos Cardíacos/patologia , Volume Sistólico , Animais , Cardiomiopatias/etiologia , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , Conectina/metabolismo , Acetato de Desoxicorticosterona/toxicidade , Dieta Ocidental , Dilatação Patológica/etiologia , Dilatação Patológica/fisiopatologia , Modelos Animais de Doenças , Feminino , Átrios do Coração/fisiopatologia , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/patologia , Hiperlipidemias/induzido quimicamente , Hiperlipidemias/complicações , Hipertensão/induzido quimicamente , Hipertrofia/etiologia , Hipertrofia/patologia , Hipertrofia Ventricular Esquerda/etiologia , Hipertrofia Ventricular Esquerda/metabolismo , Hipertrofia Ventricular Esquerda/patologia , Mineralocorticoides/toxicidade , Miócitos Cardíacos/metabolismo , Óxido Nítrico Sintase/metabolismo , Fosforilação , Isoformas de Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Superóxidos/metabolismo , Suínos
14.
J Mol Cell Cardiol ; 84: 1-9, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25828762

RESUMO

BACKGROUND: Cardiac alternans are proarrhythmic and mechanistically link cardiac mechanical dysfunction and sudden cardiac death. Beat-to-beat alternans occur when beats with large Ca(2+) transients and long action potential duration (APD) alternate with the converse. APD alternans are typically driven by Ca(2+) alternans and sarcoplasmic reticulum (SR) Ca(2+) release alternans. But the effect of intercellular communication via gap junctions (GJ) on alternans in the intact heart remains unknown. OBJECTIVE: We assessed the effects of cell-to-cell coupling on local alternans in intact Langendorff-perfused mouse hearts, measuring single myocyte [Ca(2+)] alternans synchronization among neighboring cells, and effects of ß-adrenergic receptor (ß-AR) activation and reduced GJ coupling. METHODS AND RESULTS: Mouse hearts (C57BL/6) were retrogradely perfused and loaded with Fluo8-AM to record cardiac myocyte [Ca(2+)] in situ with confocal microscopy. Single cell resolution allowed analysis of alternans within the intact organ during alternans induction. Carbenoxolone (25 µM), a GJ inhibitor, significantly increased the occurrence and amplitude of alternans in single cells within the intact heart. Alternans were concordant between neighboring cells throughout the field of view, except transiently during onset. ß-AR stimulation only reduced Ca(2+) alternans in tissue that had reduced GJ coupling, matching effects seen in isolated myocytes. CONCLUSIONS: Ca(2+) alternans among neighboring myocytes is predominantly concordant, likely because of electrical coupling between cells. Consistent with this, partial GJ uncoupling increased propensity and amplitude of Ca(2+) alternans, and made them more sensitive to reversal by ß-AR activation, as in isolated myocytes. Electrical coupling between myocytes may thus limit the alternans initiation, but also allow alternans to be more stable once established.


Assuntos
Coração/fisiologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Receptores Adrenérgicos beta/metabolismo , Animais , Sinalização do Cálcio/efeitos dos fármacos , Junções Comunicantes/efeitos dos fármacos , Junções Comunicantes/metabolismo , Coração/efeitos dos fármacos , Técnicas In Vitro , Isoproterenol/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Microscopia Confocal , Miócitos Cardíacos/efeitos dos fármacos
15.
Eur J Heart Fail ; 17(2): 214-23, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25418979

RESUMO

AIMS: Galectin-3 is a marker of myocardial fibrosis and mediates aldosterone-induced cardiovascular inflammation and fibrosis. Characteristics of galectin-3 and its response to spironolactone have not been evaluated in heart failure with preserved ejection fraction (HFpEF). The aim of this study was to determine the association between galectin-3 levels and patient characteristics in HFpEF; to evaluate the interaction between spironolactone and galectin-3 levels; and to assess the association between galectin-3 and clinical outcomes. METHODS AND RESULTS: Aldo-DHF investigated spironolactone 25 mg once daily vs. placebo for 12 months in patients with NYHA class II-III, LVEF ≥50%, grade ≥ I diastolic dysfunction, and peakVO2 ≤ 25 mL/kg/min. Galectin-3 levels were obtained at baseline, and at 6 and 12 months. The association between baseline galectin-3, change in galectin-3, and all-cause death or hospitalization was evaluated, and the interaction between galectin-3 and treatment was assessed. Median baseline galectin-3 was 12.1 ng/mL. After multivariable adjustment, baseline galectin-3 inversely correlated with peak VO2 (P = 0.021), 6 min walk distance (P = 0.002), and Short Form 36 (SF-36) physical functioning (P = 0.001), and directly correlated with NYHA class (P = 0.007). Baseline NT-proBNP correlated with E/e' velocity ratio (P ≤ 0.001), left atrial volume index (P < 0.001), and LV mass index (P = 0.009). Increasing galectin-3 at 6 or 12 months was associated with all-cause death or hospitalization independent of treatment arm [hazard ratio (HR) 3.319, 95% confidence interval (CI) 1.214-9.07, P = 0.019] and NT-proBNP (HR 3.127, 95% CI 1.144-8.549, P = 0.026). Spironolactone did not influence galectin-3 levels. CONCLUSION: Galectin-3 levels are modestly elevated in patients with stable HFpEF and relate to functional performance and quality of life. Increasing galectin-3 was associated with worse outcome, independent of treatment or NT-proBNP.


Assuntos
Diuréticos/uso terapêutico , Galectina 3/sangue , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/tratamento farmacológico , Espironolactona/uso terapêutico , Volume Sistólico/fisiologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Função Ventricular Esquerda/efeitos dos fármacos , Remodelação Ventricular
16.
Circ Heart Fail ; 7(6): 953-9, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25277997

RESUMO

BACKGROUND: Elevated high-sensitivity troponin is associated with increasing disease severity in patients with stable heart failure with reduced ejection fraction, but less is known about the association in heart failure with preserved ejection fraction. METHODS AND RESULTS: We examined the prevalence of elevated high-sensitivity troponin T (hs-TnT) in 298 patients with heart failure with preserved ejection fraction enrolled in the Prospective comparison of angiotensin receptor neprilysin inhibitor with angiotensin receptor blocker on Management Of heart failUre with preserved ejectioN fracTion (PARAMOUNT) trial, in which the angiotensin receptor neprilysin inhibitor LCZ696 reduced markers of heart failure severity compared with valsartan. We assessed the association between hs-TnT and cardiac structure and function, and the effect of LCZ696, compared with valsartan, on hs-TnT over 36 weeks. Elevated hs-TnT in the myocardial injury range (>0.014 µg/L) was found in 55% of patients and was associated with older age, history of diabetes mellitus, higher N-terminal pro-brain natriuretic peptide, lower estimated glomerular filtration rate, and larger left atrial size, left ventricular volume, and mass. LCZ696 treatment reduced hs-TnT to a greater extent at 12 weeks (12% reduction; P=0.05) and at 36 weeks (14% reduction; P=0.03) compared with valsartan. CONCLUSIONS: Troponin T was elevated in a substantial number of patients enrolled in a heart failure with preserved ejection fraction clinical trial and was associated with abnormalities of cardiac structure, function, and elevated baseline N-terminal pro-brain natriuretic peptide. Decreases in hs-TnT with LCZ696 in parallel with improvement in N-terminal pro-brain natriuretic peptide and left atrial size suggest that the angiotensin receptor neprilysin inhibitor LCZ696 may reduce this measure of myocardial injury in heart failure with preserved ejection fraction. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00887588.


Assuntos
Aminobutiratos/uso terapêutico , Antagonistas de Receptores de Angiotensina/uso terapêutico , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/tratamento farmacológico , Neprilisina/antagonistas & inibidores , Tetrazóis/uso terapêutico , Troponina T/sangue , Idoso , Idoso de 80 Anos ou mais , Bloqueadores do Receptor Tipo 1 de Angiotensina II/uso terapêutico , Feminino , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Peptídeo Natriurético Encefálico/uso terapêutico , Fragmentos de Peptídeos/uso terapêutico , Valina/análogos & derivados , Valina/uso terapêutico , Valsartana
17.
Eur Heart J ; 35(40): 2797-815, 2014 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-25104786

RESUMO

The management of heart failure with reduced ejection fraction (HF-REF) has improved significantly over the last two decades. In contrast, little or no progress has been made in identifying evidence-based, effective treatments for heart failure with preserved ejection fraction (HF-PEF). Despite the high prevalence, mortality, and cost of HF-PEF, large phase III international clinical trials investigating interventions to improve outcomes in HF-PEF have yielded disappointing results. Therefore, treatment of HF-PEF remains largely empiric, and almost no acknowledged standards exist. There is no single explanation for the negative results of past HF-PEF trials. Potential contributors include an incomplete understanding of HF-PEF pathophysiology, the heterogeneity of the patient population, inadequate diagnostic criteria, recruitment of patients without true heart failure or at early stages of the syndrome, poor matching of therapeutic mechanisms and primary pathophysiological processes, suboptimal study designs, or inadequate statistical power. Many novel agents are in various stages of research and development for potential use in patients with HF-PEF. To maximize the likelihood of identifying effective therapeutics for HF-PEF, lessons learned from the past decade of research should be applied to the design, conduct, and interpretation of future trials. This paper represents a synthesis of a workshop held in Bergamo, Italy, and it examines new and emerging therapies in the context of specific, targeted HF-PEF phenotypes where positive clinical benefit may be detected in clinical trials. Specific considerations related to patient and endpoint selection for future clinical trials design are also discussed.


Assuntos
Insuficiência Cardíaca/terapia , Aminobutiratos/uso terapêutico , Anemia/prevenção & controle , Antagonistas de Receptores de Angiotensina/uso terapêutico , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Arritmias Cardíacas/prevenção & controle , Cardiotônicos/uso terapêutico , Ensaios Clínicos como Assunto , Angiopatias Diabéticas/prevenção & controle , Diuréticos/uso terapêutico , Terapia por Exercício/métodos , Insuficiência Cardíaca/fisiopatologia , Homeostase , Humanos , Hipertensão Pulmonar/prevenção & controle , Ferro/deficiência , Antagonistas de Receptores de Mineralocorticoides/uso terapêutico , Terapia de Alvo Molecular/métodos , Obesidade/prevenção & controle , Estudos Observacionais como Assunto , Seleção de Pacientes , Fenótipo , Inibidores da Fosfodiesterase 5/uso terapêutico , Bloqueadores dos Canais de Sódio/uso terapêutico , Volume Sistólico/fisiologia , Tetrazóis/uso terapêutico , Rigidez Vascular/fisiologia
18.
J Cardiovasc Electrophysiol ; 25(7): 671-9, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24798070

RESUMO

INTRODUCTION: The atrial outcome after extensive ablation is unknown. We sought to quantify atrial structure and function years after successful ablation for persistent atrial fibrillation (PsAF). METHODS AND RESULTS: We studied after 80 ± 15 months 26 patients (54 ± 8 years, 1 woman) with PsAF successfully treated by ablation (2.2 ± 0.7 stepwise approach procedures, cumulative RF duration 126 ± 37 minutes). At follow-up atrial scar burden and atrial outflows were quantified using delayed-enhanced and velocity-encoded MRI, respectively. Cine imaging was used to quantify atrial conduit function (CF), active emptying fraction (AEF), expansion index (EI), and the inter-appendage mechanical activation delay. Patients underwent exercise testing at baseline and follow-up. LA and RA scar extent were 29 ± 6 and 4.3 ± 2.8%, respectively. LA and RA AEF were 10.0 ± 5.3 and 30 ± 8%. Mean inter-appendage delay was 83 ± 47 ms [42-217]. Complete LAA isolation was found in 3 patients. A wave was absent in 9/26 patients. LA scar extent related to the number of procedures (R = 0.58, P = 0.002) and total RF duration (R = 0.56, P = 0.003). Among follow-up characteristics, LA scar extent related to LAAEF (R = -0.73, P < 0.0001), LAEI (R = -0.64, P = 0.0003), A-wave peak (R = -0.72, P < 0.0001), and inter-appendage mechanical delay (R = 0.47, P = 0.02). At multivariable analysis, LA scar extent was independently related to LAAEF and LAEI. LAAEF and LA scar extent correlated with exercise capacity at follow-up (R = 0.44, P = 0.02, and R = -0.40; P = 0.04). CONCLUSION: LA contractility and compliance are markedly impaired years after successful PsAF ablation. LA dysfunction is closely related to scar burden.


Assuntos
Fibrilação Atrial/cirurgia , Função do Átrio Esquerdo , Remodelamento Atrial , Ablação por Cateter/efeitos adversos , Cicatriz/etiologia , Átrios do Coração/cirurgia , Imagem Cinética por Ressonância Magnética , Potenciais de Ação , Adulto , Idoso , Fibrilação Atrial/patologia , Fibrilação Atrial/fisiopatologia , Cicatriz/patologia , Cicatriz/fisiopatologia , Complacência (Medida de Distensibilidade) , Teste de Esforço , Feminino , Átrios do Coração/patologia , Átrios do Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Contração Miocárdica , Fatores de Tempo , Resultado do Tratamento
19.
Heart Fail Rev ; 19(2): 135-52, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23099992

RESUMO

There are over 1 million hospitalizations for heart failure (HF) annually in the United States alone, and a similar number has been reported in Europe. Recent clinical trials investigating novel therapies in patients with hospitalized HF (HHF) have been negative, and the post-discharge event rate remains unacceptably high. The lack of success with HHF trials stem from problems with understanding the study drug, matching the drug to the appropriate HF subgroup, and study execution. Related to the concept of study execution is the importance of including appropriate study sites in HHF trials. Often overlooked issues include consideration of the geographic region and the number of patients enrolled at each study center. Marked differences in baseline patient co-morbidities, serum biomarkers, treatment utilization and outcomes have been demonstrated across geographic regions. Furthermore, patients from sites with low recruitment may have worse outcomes compared to sites with higher enrollment patterns. Consequently, sites with poor trial enrollment may influence key patient end points and likely do not justify the costs of site training and maintenance. Accordingly, there is an unmet need to develop strategies to identify the right study sites that have acceptable patient quantity and quality. Potential approaches include, but are not limited to, establishing a pre-trial registry, developing site performance metrics, identifying a local regionally involved leader and bolstering recruitment incentives. This manuscript summarizes the roundtable discussion hosted by the Food and Drug Administration between members of academia, the National Institutes of Health, industry partners, contract research organizations and academic research organizations on the importance of selecting optimal sites for successful trials in HHF.


Assuntos
Ensaios Clínicos como Assunto/métodos , Insuficiência Cardíaca/terapia , Hospitalização , Seleção de Pacientes , Terapias em Estudo , Humanos , Pacientes Internados , Projetos de Pesquisa , Estados Unidos
20.
Front Physiol ; 5: 517, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25628569

RESUMO

Dyssynchronous local Ca release within individual cardiac myocytes has been linked to cellular contractile dysfunction. Differences in Ca kinetics in adjacent cells may also provide a substrate for inefficient contraction and arrhythmias. In a new approach we quantify variation in local Ca transients between adjacent myocytes in the whole heart. Langendorff-perfused mouse hearts were loaded with Fluo-8 AM to detect Ca and Di-4-ANEPPS to visualize cell membranes. A spinning disc confocal microscope with a fast camera allowed us to record Ca signals within an area of 465 µm by 315 µm with an acquisition speed of 55 fps. Images from multiple transients recorded at steady state were registered to their time point in the cardiac cycle to restore averaged local Ca transients with a higher temporal resolution. Local Ca transients within and between adjacent myocytes were compared with regard to amplitude, time to peak and decay at steady state stimulation (250 ms cycle length). Image registration from multiple sequential Ca transients allowed reconstruction of high temporal resolution (2.4 ± 1.3 ms) local CaT in 2D image sets (N = 4 hearts, n = 8 regions). During steady state stimulation, spatial Ca gradients were homogeneous within cells in both directions and independent of distance between measured points. Variation in CaT amplitudes was similar across the short and the long side of neighboring cells. Variations in TAU and TTP were similar in both directions. Isoproterenol enhanced the CaT but not the overall pattern of spatial heterogeneities. Here we detected and analyzed local Ca signals in intact mouse hearts with high temporal and spatial resolution, taking into account 2D arrangement of the cells. We observed significant differences in the variation of CaT amplitude along the long and short axis of cardiac myocytes. Variations of Ca signals between neighboring cells may contribute to the substrate of cardiac remodeling.

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