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1.
Rev. port. cardiol ; 41(9): 771-779, Sept. 2022. graf, ilus, tab
Artigo em Inglês | Sec. Est. Saúde SP, CONASS, SESSP-IDPCPROD, Sec. Est. Saúde SP | ID: biblio-1393130

RESUMO

INTRODUCTION AND OBJECTIVES: Hypertrophic cardiomyopathy (HCM) is accompanied by pathophysiological changes that predispose to the development of atrial fibrillation (AF). This arrhythmia impacts negatively on the morbidity, mortality and quality of life of these patients. Our objective was to evaluate the behavior of left atrial function, by means of atrial strain (derived from speckle tracking) and volumetric analysis by three-dimensional echocardiography, in patients with HCM with paroxysmal AF. METHOD: We analysed left atrial function in 53 patients with HCM, 25 of whom were paroxysmal AF carriers (mean age 61.7±9.9 years; 56% female) compared with 28 members of the control group (mean age 60.5±10 years; 53.6% female) who were matched especially for sex, age and other demographic data. RESULTS: It was observed that patients with HCM and a history of paroxysmal AF had lower left atrial emptying fractions than individuals in the control group; and the active atrial emptying fraction was a factor independently associated with the presence of this arrhythmia (p=0.018; odds ratio=0.93). Moreover, we found a significant reduction of the left atrial strain in all its components in the total sample of patients, with no difference between the groups. CONCLUSIONS: Measurements of atrial emptying fractions by three-dimensional echocardiography allowed differentiating patients with HCM with and without paroxysmal AF.


Assuntos
Fibrilação Atrial , Cardiomiopatia Hipertrófica , Função Atrial , Ecocardiografia Tridimensional
2.
Eur J Appl Physiol ; 122(12): 2585-2596, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36088588

RESUMO

PURPOSE: Athlete's heart encompasses multiple physiological cardiac adaptations, although less is known at atrial level. How sex may influence the type and extent of atrial adaptations to exercise stimuli is also unknown. Our objective was to compare gender differences of echocardiographic atrial function indices in response to exercise in endurance athletes (EAs). METHODS: Highly trained (> 10 h/week) endurance athletes performed a maximal cardiopulmonary exercise test (CPET). Echocardiographic evaluation was performed at rest and immediately after exercise. Atria analysis consisted of standard and speckle-tracking echocardiographic assessment of atrial dimensions and contractile, reservoir, and conduit functions with myocardial deformation. RESULTS: 80 EAs (55% women) were enrolled and performed excellent CPET (129.6% of predicted VO2 maximal consumption). At rest, left atrial (LA) volumes and strain were similar between men and women. Women had lower right atrial (RA) volumes (26.7 vs 32.9 ml/m2, p < 0.001) and higher reservoir and conduit strain absolute values. After exercise, women exhibited a larger improvement in reservoir and conduit LA strain, and the same trend was observed for the RA. In EAs with LA dilatation on baseline (~ 50%), women persistently showed higher increase in reservoir and conduit strain profile with exercise compared to men. CONCLUSION: In highly trained EAs, women have similar or even lower atrial dimensions remodelling compared to men, but better function based on reservoir and conduit strain values both at rest and in response to exercise. This phenomenon should be confirmed in larger studies and its potential role in the development of supraventricular arrhythmias, addressed in a specifically designed protocol.


Assuntos
Função Atrial , Átrios do Coração , Masculino , Humanos , Feminino , Átrios do Coração/diagnóstico por imagem , Função Atrial/fisiologia , Ecocardiografia , Exercício Físico , Atletas
4.
Artigo em Inglês | MEDLINE | ID: mdl-35301521

RESUMO

OBJECTIVES: Atrial function in Fontan patients is unknown. Our goal was to report the relationship of atrial function with the cardiac index and atrial function and clinical outcome through longer follow-up periods. METHODS: Twelve patients were followed up for over 20 years after their first Fontan operation. Atrial function, including the expansion index, atrial ejection fraction, passive ejection fraction and active ejection fraction, was examined using cardiac computed tomography. The relationship of atrial function with the cardiac index and failing Fontan patients was analysed. RESULTS: Twelve Fontan patients were included. The median follow-up period after the first Fontan operation was 27 (range, 21-33) years, and the median age of those examined was 33.5 (range, 24-60) years. There were 6 male patients (50%). The cardiac index showed a significant positive correlation with the expansion index (P = 0.02), the atrial ejection fraction (P = 0.035), and the active ejection fraction (P = 0.013). The expansion index (39.2 ± 19.6 vs 64.1 ± 3.9), atrial ejection fraction (26.6 ± 10.9 vs 39.0 ± 1.5%), booster pump (15.6 ± 9.0 vs 31.3 ± 3.5) and cardiac index (2.1 ± 0.3 vs 2.5 ± 0.2 L/min/m2) were significantly lower in patients with a history of arrhythmia than in patients without a history of arrhythmia (P < 0.05). The expansion index (23.5 ± 13.5 vs 59.5 ± 8.7), atrial ejection fraction (18.1 ± 8.6 vs 37.1 ± 3.7) and active ejection fraction (7.3 ± 2.7 vs 27.7 ± 5.2) were significantly lower in failing Fontan patients than in non-failing Fontan patients (P < 0.01). CONCLUSIONS: Patients with atrial arrhythmia and signs of Fontan failure have lower atrial function than those without.


Assuntos
Técnica de Fontan , Cardiopatias Congênitas , Adulto , Arritmias Cardíacas/cirurgia , Função Atrial , Técnica de Fontan/efeitos adversos , Cardiopatias Congênitas/diagnóstico por imagem , Cardiopatias Congênitas/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Volume Sistólico , Função Ventricular Esquerda , Adulto Jovem
5.
J Echocardiogr ; 20(1): 33-41, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34476735

RESUMO

BACKGROUND: Percutaneous occlusion of atrial septal defect (ASD) has recently become a standard therapeutic strategy, but little is known about atria function thereafter. Strain analysis by two-dimensional speckle tracking echocardiography (2D-STE) is considered to be a new tool to assess myocardial function. METHODS: This study aimed to evaluate atria function by quantifying longitudinal strain in patients with chronic RV volume overload due to ASD before and after percutaneous closure using 2D-STE. 28 consecutive patients underwent percutaneous closure of ASD (18 female, 10 male) were examined, clinical and echocardiographic evaluation one day before, 1 day, and one month after percutaneous closure of ASD. Peak longitudinal systolic strain and strain rate of both atria were analyzed by 2D-STE. RESULTS: Mean age of the patients was 15.07 ± 8.39 years; mean diameter of ASD was 16.01 ± 2.78 mm; left atrium (LA) diameter significantly increased after ASD closure; and peak longitudinal strain of RA increased significantly one day and one month after ASD closure (48. 77 ± 4.40, vs.55.36 ± 3.70 and, vs. 62.13 ± 3.81%, p = 0.001). LA longitudinal strain significantly decreased after ASD closure (42.55 ± 4.57, vs. 34.79 ± 3.20%, p = 0.001). Furthermore, negative correlation was found between the size of the ASD and delta LA systolic strain and strain rate. CONCLUSIONS: 2D-STE can be considered a feasible and simple technique for assessment of atrial deformation in ASD patients, and it useful to assess the effect of percutaneous ASD closure on atrial reservoir function by measuring peak atrial longitudinal strain.


Assuntos
Comunicação Interatrial , Adolescente , Adulto , Função Atrial , Criança , Ecocardiografia/métodos , Feminino , Átrios do Coração/diagnóstico por imagem , Comunicação Interatrial/diagnóstico , Comunicação Interatrial/cirurgia , Humanos , Masculino , Resultado do Tratamento , Adulto Jovem
6.
Am Heart J ; 244: 36-41, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34688651

RESUMO

Atrial fibrillation (AF) and heart failure with preserved ejection fraction (HFpEF) are 2 cardiovascular conditions that often coexist. Strain phases of both the left and right atria are more impaired in paroxysmal AF patients with HFpEF than those without HFpEF in spite of comparable global longitudinal strain of the left ventricle. Atrial function may differentiate paroxysmal AF patients with HFpEF from those without HFpEF.


Assuntos
Fibrilação Atrial , Insuficiência Cardíaca , Fibrilação Atrial/complicações , Função Atrial , Átrios do Coração/diagnóstico por imagem , Insuficiência Cardíaca/complicações , Humanos , Volume Sistólico
7.
Cell Mol Life Sci ; 78(23): 7309-7337, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34704115

RESUMO

Human atrial and ventricular contractions have distinct mechanical characteristics including speed of contraction, volume of blood delivered and the range of pressure generated. Notably, the ventricle expresses predominantly ß-cardiac myosin while the atrium expresses mostly the α-isoform. In recent years exploration of the properties of pure α- & ß-myosin isoforms have been possible in solution, in isolated myocytes and myofibrils. This allows us to consider the extent to which the atrial vs ventricular mechanical characteristics are defined by the myosin isoform expressed, and how the isoform properties are matched to their physiological roles. To do this we Outline the essential feature of atrial and ventricular contraction; Explore the molecular structural and functional characteristics of the two myosin isoforms; Describe the contractile behaviour of myocytes and myofibrils expressing a single myosin isoform; Finally we outline the outstanding problems in defining the differences between the atria and ventricles. This allowed us consider what features of contraction can and cannot be ascribed to the myosin isoforms present in the atria and ventricles.


Assuntos
Átrios do Coração/metabolismo , Ventrículos do Coração/metabolismo , Contração Miocárdica/fisiologia , Miócitos Cardíacos/fisiologia , Miosinas Ventriculares/metabolismo , Sequência de Aminoácidos , Função Atrial/fisiologia , Pressão Sanguínea/fisiologia , Humanos , Miócitos Cardíacos/metabolismo , Miofibrilas/fisiologia , Domínios Proteicos , Isoformas de Proteínas , Função Ventricular/fisiologia
8.
Naunyn Schmiedebergs Arch Pharmacol ; 394(12): 2401-2418, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34562141

RESUMO

In the past, we generated transgenic mice that overexpress the human histamine 2 (H2)-receptor (H2-TG) or that overexpress the human serotonin 4 (5-HT4)-receptor (5-HT4-TG) in the heart. Here, we crossbred these lines of mice to generate double transgenic mice that overexpress both receptors (DT). This was done to study a conceivable interaction between these receptors in the mouse heart as a model for the human heart. When in left atria, initially, force of contraction was elevated maximally with 1 µM serotonin, and subsequently, histamine was cumulatively applied; a biphasic effect of histamine was noted: the force of contraction initially decreased, maximally at 10 nM histamine, and thereafter, the force of contraction increased again at 1 µM histamine. Notably, functional interaction between 5-HT and histamine was also identified in isolated electrically stimulated trabeculae carneae from human right atrium (obtained during cardiac surgery). These functional and biochemical data together are consistent with a joint overexpression of inotropically active H2-receptors and 5-HT4-receptors in the same mouse heart. We also describe an antagonistic interaction on the force of contraction of both receptors in the mouse atrium (DT) and in the human atrial muscle strips. We speculate that via this interaction, histamine might act as a "brake" on the cardiac actions of 5-HT via inhibitory GTP-binding proteins acting on the activity of adenylyl cyclase.


Assuntos
Função Atrial/fisiologia , Átrios do Coração/metabolismo , Receptores 5-HT2 de Serotonina/metabolismo , Receptores 5-HT4 de Serotonina/metabolismo , Adenilil Ciclases/metabolismo , Idoso , Animais , Proteínas de Ligação ao GTP/metabolismo , Histamina/metabolismo , Humanos , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Receptores 5-HT2 de Serotonina/genética , Receptores 5-HT4 de Serotonina/genética , Serotonina/metabolismo , Especificidade da Espécie
9.
Cells ; 10(6)2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208565

RESUMO

The voltage-gated Na+ channel Nav1.5 is critical for normal cardiac myocyte excitability. Mathematical models have been widely used to study Nav1.5 function and link to a range of cardiac arrhythmias. There is growing appreciation for the importance of incorporating physiological heterogeneity observed even in a healthy population into mathematical models of the cardiac action potential. Here, we apply methods from Bayesian statistics to capture the variability in experimental measurements on human atrial Nav1.5 across experimental protocols and labs. This variability was used to define a physiological distribution for model parameters in a novel model formulation of Nav1.5, which was then incorporated into an existing human atrial action potential model. Model validation was performed by comparing the simulated distribution of action potential upstroke velocity measurements to experimental measurements from several different sources. Going forward, we hope to apply this approach to other major atrial ion channels to create a comprehensive model of the human atrial AP. We anticipate that such a model will be useful for understanding excitability at the population level, including variable drug response and penetrance of variants linked to inherited cardiac arrhythmia syndromes.


Assuntos
Potenciais de Ação/fisiologia , Função Atrial/fisiologia , Simulação por Computador , Modelos Teóricos , Canal de Sódio Disparado por Voltagem NAV1.5/fisiologia , Fibrilação Atrial/fisiopatologia , Teorema de Bayes , Humanos , Miócitos Cardíacos/fisiologia
10.
Fish Physiol Biochem ; 47(4): 1329-1339, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34241764

RESUMO

The spatial-temporal organization of the activation, repolarization and hemodynamics of the heart ventricle in rainbow trout, Oncorhynchus mykiss, adapted to a temperature of 5-7 °C, were studied from the normal sinus rhythm (21.6 ± 4.9 bpm) to the highest possible heart rhythm (HR) (60 bpm), during which deterioration of the contractile activity of the myocardium occurred. Regardless of the HR, the main pattern of excitation of the heart ventricle was the movement of the depolarization wave from the dorsal areas of the base in the base-apical and ventral directions with the capture of the entire thickness of the walls, with a slight difference in the time of activation of the subendocardium compared to the subepicardium. The increase in HR above the sinus rhythm caused significant shortening of local repolarization durations in all areas and layers (endocardial, intramural and subepicardial) of the heart ventricle. Changes in local durations of repolarization led to an increase in the heterogeneity of repolarization of the ventricular myocardium; as a result, a deterioration of its contractility was observed. In relation to the sinus rhythm, the maximal systolic pressure in the heart ventricle decreased, the diastolic and end-diastolic pressure increased, and the maximum rates of pressure rise and fall decreased. In rainbow trout adapted to a temperature of 5-7 °C at sinus rhythm, the pumping function of the heart was probably within the upper limit of the physiological norm, and a further increase in the heart rate led to a decline in myocardial contractility.


Assuntos
Função Atrial , Oncorhynchus mykiss/fisiologia , Função Ventricular , Animais , Estimulação Elétrica , Feminino , Átrios do Coração , Frequência Cardíaca , Ventrículos do Coração , Hemodinâmica , Masculino , Contração Miocárdica
11.
Vet Res Commun ; 45(4): 319-327, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34244914

RESUMO

The His bundle is a part of the specialized electrical conduction system that provides a connection between the atrial and ventricular myocardial compartments in both normal and abnormal hearts. The aim of this study was to perform a morphometric analysis of His bundle characteristics of in humans, dogs, horses and pigs and compare them in these studied species. Histological sections of 5 µm thickness were obtained and stained with hematoxylin-eosin and Masson's trichrome; the desmin and periodic acid-Schiff methods were also used for precise identification of cells. The His bundle was found to be longer in horses (2.85 ± 1.02 mm) and pigs (1.77 ± 0.9 mm) than in dogs (1.53 ± 0.8 mm) or humans, in which it was shortest (1.06 ± 0.6 mm). The area and diameters in His bundle cells, were significantly larger in pigs and horses than in humans (p < 0.001) or dogs (p < 0.001). We found two organizational patterns of His bundle components: group I, with large cells and a high amount of collagen fibers in ungulates (pigs and horses); and group II, with smaller cells and lower abundance of collagen fibers in humans and dogs. Documenting cell size variations in the His bundle allows us not only to identify this bundle by histological or anatomical location but also to differentiate these cells from others such as nodal or Purkinje cells. Our analysis revealed that His bundle cells have discrete identities based on their morphometric and histological characteristics.


Assuntos
Função Atrial/fisiologia , Fascículo Atrioventricular/fisiologia , Cães/fisiologia , Cavalos/fisiologia , Sus scrofa/fisiologia , Função Ventricular/fisiologia , Animais , Humanos , Masculino
14.
J Cardiovasc Pharmacol ; 78(2): 184-191, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-34173807

RESUMO

ABSTRACT: In risk-stratifying patients with atrial fibrillation (AF), physicians rely heavily on clinical parameters that provide risk scores and determine treatment strategies. There has been increasing research on potential biomarkers in the blood that could more accurately determine both risk of complications in AF and risk of incidence of AF. This review highlights the clinical significance of 5 novel biomarkers that have been shown to be linked to AF. These biomarkers are carbohydrate antigen 125, galectin-3, growth differentiation factor-15, a member of the interleukin 1 receptor family, IL1RL1 (ST2), and N-terminal pro B-type natriuretic peptide.


Assuntos
Fibrilação Atrial/sangue , Função Atrial , Biomarcadores/sangue , Átrios do Coração/metabolismo , Potenciais de Ação , Animais , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/fisiopatologia , Fibrilação Atrial/terapia , Proteínas Sanguíneas , Antígeno Ca-125/sangue , Tomada de Decisão Clínica , Galectinas/sangue , Fator 15 de Diferenciação de Crescimento/sangue , Átrios do Coração/fisiopatologia , Frequência Cardíaca , Humanos , Proteínas de Membrana/sangue , Peptídeo Natriurético Encefálico/sangue , Fragmentos de Peptídeos/sangue , Valor Preditivo dos Testes , Prognóstico , Receptores Tipo I de Interleucina-1/sangue
15.
Eur J Pharmacol ; 906: 174206, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34048737

RESUMO

We investigated whether hypothermia would be arrhythmogenic in mice that overexpress the human 5-HT4 receptor only in their cardiac myocytes (5-HT4-TG). Contractile studies were performed in isolated, electrically driven (1 Hz) left and spontaneously beating right atrial preparations of 5-HT4-TG and littermate wild-type control mice (WT). Hypothermia (23 °C) decreased the force of contraction in the mouse right and left atrial preparations. Moreover, the concentration-dependent positive inotropic effects of 5-HT were blunted but still shifted to lower 5-HT concentrations in the left 5-HT4-TG atria in hypothermia compared to normothermia (37 °C). Furthermore, hypothermia increased the incidence of right atrial arrhythmias in 5-HT4-TG more than in WT mice. In contrast, at 37 °C, lowering the potassium concentration from 5.2 to 2.0 mM also induced arrhythmias in the right atrium, but with a similar incidence in WT and 5-HT4-TG mice. In contrast, 10 µM d,l-sotalol and 300 µM erythromycin did not induce arrhythmias. Hypothermia was accompanied by the increased expression of heat shock protein 70 (HSP70) in WT but not in 5-HT4-TG mice. We concluded that without the stimulation of 5-HT4-receptors by exogenous agonists, a simple temperature reduction can increase arrhythmias in 5-HT4-TG mice. It is tempting to speculate that in human patients, 5-HT4 receptors might contribute to potentially deadly hypothermia-induced arrhythmias.


Assuntos
Arritmias Cardíacas/etiologia , Função Atrial/fisiologia , Hipotermia/complicações , Receptores 5-HT4 de Serotonina/metabolismo , Animais , Arritmias Cardíacas/fisiopatologia , Modelos Animais de Doenças , Humanos , Preparação de Coração Isolado , Camundongos , Camundongos Transgênicos , Contração Miocárdica/fisiologia , Miócitos Cardíacos/metabolismo , Receptores 5-HT4 de Serotonina/genética
16.
PLoS One ; 16(4): e0250089, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33852637

RESUMO

BACKGROUND: Standard apical four-chamber and two-chamber views often maximize the long-axis of the left ventricle, resulting in artifactitious foreshortening of the left atrium (LA), which may overestimate LA longitudinal reservoir strain (LALS). We compared LALS values between 2D echocardiography (2DE) and 3D echocardiography (3DE) in healthy subjects to determine whether 2DE speckle tracking analysis overestimates the reference value of LALS. METHODS AND RESULTS: In this study, 4 types of cohorts were included: 1. 105 normal subjects (retrospectively), 2. 53 patients with cardiovascular diseases (retrospectively), 3. 15 patients who received cardiac magnetic resonance (prospectively), and 4. 20 normal subjects (prospectively). LALS and LA length were measured using both 2DE and 3DE in 105 healthy subjects (median age: 42 years). Biplane LALS was measured in apical four- and two-chamber views using 2DE speckle tracking software, and 3DE LALS was measured using new 3DE LA strain software. To determine sensitivity, we also performed the same analysis in 53 patients with cardiovascular disease. The mean value of biplane LALS was 39.6%. LA length at both end-diastole (r = -0.43) and end-systole (r = -0.54) was negatively correlated with biplane LALS. Multivariate regression analysis revealed that both end-diastolic and end-systolic LA length had significant negative relationships with biplane LALS after adjusting for anthropometric and echocardiographic image quality parameters. 3DE LALS (23.7±7.6%) gave significantly lower values than 2DE LALS (39.5±12.0%, p<0.001) with a weak correlation (r = 0.33). LA length measured by 2DE was significantly shorter than that measured by 3DE. The same trend was observed in diseased patients. CONCLUSIONS: Our results revealed that in 2DE, the LA cavity consistently appears longitudinally foreshortened in apical views, potentially overestimating LALS. 3DE may overcome this limitation.


Assuntos
Função Atrial/fisiologia , Ecocardiografia Tridimensional/métodos , Adulto , Apêndice Atrial/fisiologia , Estudos de Coortes , Diástole/fisiologia , Ecocardiografia/métodos , Feminino , Átrios do Coração/patologia , Ventrículos do Coração/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Reprodutibilidade dos Testes , Estudos Retrospectivos
17.
J Am Heart Assoc ; 10(6): e017519, 2021 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-33666093

RESUMO

Background Sustained atrial high-rate episodes (SAHREs) among individuals with a cardiac implantable electronic device are associated with an increased risk of adverse outcomes. Risk stratification for the development of SAHREs has never been investigated. We aimed to assess the performance of the C2HEST (coronary artery disease or chronic obstructive pulmonary disease [1 point each], hypertension [1 point], elderly [age ≥75 years, 2 points], systolic heart failure [2 points], thyroid disease [1 point]) score in predicting SAHREs in patients with cardiac implantable electronic devices without atrial fibrillation. Methods and Results Five Hundred consecutive patients with cardiac implantable electronic devices in the West Birmingham Atrial Fibrillation Project in the United Kingdom were followed since the procedure to observe the development of SAHREs, defined by atrial high-rate episodes lasting >24 hours. Risk factors and incidence of SAHREs were analyzed. The predictive value of the C2HEST score for SAHRE prediction was evaluated. Over a mean follow-up of 53.1 months, 44 (8.8%) patients developed SAHREs. SAHREs were associated with higher all-cause mortality (P<0.001) and ischemic stroke (P=0.001). Age and heart failure were associated with SAHRE occurrence. The incidence of SAHREs increased by the C2HEST score (39% higher risk per point increase). Among patients with a C2HEST score ≥4, the incidence of SAHREs was 3.62% per year (95% CI, 2.14-5.16). The C2HEST score had moderate predictive capability (area under the curve, 0.73; 95% CI, 0.64-0.81) and discriminative ability (log-rank P=0.003), which was better than other clinical scores (CHA2DS2-VASc, CHADS2, HATCH). Conclusions The C2HEST score predicted SAHRE incidence in patients without atrial fibrillation who had an cardiac implantable electronic device, with the highest risk seen in patients with a C2HEST score ≥4 The benefit of using the C2HEST score in clinical practice in this patient population needs further investigation.


Assuntos
Fibrilação Atrial/diagnóstico , Função Atrial/fisiologia , Átrios do Coração/fisiopatologia , Frequência Cardíaca/fisiologia , Medição de Risco/métodos , Acidente Vascular Cerebral/epidemiologia , Idoso , Fibrilação Atrial/epidemiologia , Fibrilação Atrial/fisiopatologia , Feminino , Seguimentos , Humanos , Incidência , Masculino , Estudos Retrospectivos , Fatores de Risco , Acidente Vascular Cerebral/etiologia , Reino Unido/epidemiologia
18.
Int J Cardiovasc Imaging ; 37(6): 1891-1902, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33547622

RESUMO

High altitude (HA) exposure has been considered as a cardiac stress and might impair ventricular diastolic function. Atrial contraction is involved in ventricular passive filling, however the atrial performance to HA exposure is poorly understood. This study aimed to evaluate the effect of short-term HA exposure on bi-atrial function. Physiological and 2D-echocardiographic data were collected in 82 healthy men at sea level (SL, 400 m) and 4100 m after an ascent within 7 days. Atrial function was measured using volumetric and speckle-tracking analyses during reservoir, conduit and contractile phases of cardiac cycle. Following HA exposure, significant decreases of reservoir and conduit function indexes were observed in bi-atria, whereas decreases of contractile function indexes were observed in right atrium (RA), estimated via RA active emptying fraction (SL 41.7 ± 13.9% vs. HA 35.4 ± 12.2%, p = 0.001), strain during the contractile phase [SL 13.5 (11.4, 17.8) % vs. HA 12.3 (9.3, 15.9) %, p = 0.003], and peak strain rate during the contractile phase [SL - 1.76 (- 2.24, - 1.48) s-1 vs. HA - 1.57 (- 2.01, - 1.23) s-1, p = 0.002], but not in left atrium (LA). In conclusion, short-term HA exposure of healthy individuals impairs bi-atrial performance, mostly observed in RA. Especially, atrial contractile function decreases in RA rather than LA, which seems not to compensate for decreased ventricular filling after HA exposure. Our findings may provide a novel evidence for right-sided heart dysfunction to HA exposure.


Assuntos
Altitude , Átrios do Coração , Função Atrial , Voluntários Saudáveis , Átrios do Coração/diagnóstico por imagem , Humanos , Masculino , Valor Preditivo dos Testes
19.
PLoS One ; 16(2): e0247107, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33600469

RESUMO

BACKGROUND: High altitude exposure induces overload of right-sided heart and may further predispose to supraventricular arrhythmia. It has been reported that atrial mechanical dyssynchrony is associated with atrial arrhythmia. Whether high altitude exposure causes higher right atrial (RA) dyssynchrony is still unknown. The aim of study was to investigate the effect of high altitude exposure on right atrial mechanical synchrony. METHODS: In this study, 98 healthy young men underwent clinical examination and echocardiography at sea level (400 m) and high altitude (4100 m) after an ascent within 7 days. RA dyssynchrony was defined as inhomogeneous timing to peak strain and strain rate using 2D speckle-tracking echocardiography. RESULTS: Following high altitude exposure, standard deviation of the time to peak strain (SD-TPS) [36.2 (24.5, 48.6) ms vs. 21.7 (12.9, 32.1) ms, p<0.001] and SD-TPS as percentage of R-R' interval (4.6 ± 2.1% vs. 2.5 ± 1.8%, p<0.001) significantly increased. Additionally, subjects with higher SD-TPS (%) at high altitude presented decreased right ventricular global longitudinal strain and RA active emptying fraction, but increased RA minimal volume index, which were not observed in lower group. Multivariable analysis showed that mean pulmonary arterial pressure and tricuspid E/A were independently associated with SD-TPS (%) at high altitude. CONCLUSION: Our data for the first time demonstrated that high altitude exposure causes RA dyssynchrony in healthy young men, which may be secondary to increased pulmonary arterial pressure. In addition, subjects with higher RA dyssynchrony presented worse RA contractile function and right ventricular performance.


Assuntos
Função Atrial/fisiologia , Altitude , Ecocardiografia , Humanos , Modelos Lineares , Masculino , Artéria Pulmonar/fisiologia , Estudos Retrospectivos , Adulto Jovem
20.
Circ Genom Precis Med ; 14(2): e003144, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33629867

RESUMO

BACKGROUND: KCNMA1 encodes the α-subunit of the large-conductance Ca2+-activated K+ channel, KCa1.1, and lies within a linkage interval for atrial fibrillation (AF). Insights into the cardiac functions of KCa1.1 are limited, and KCNMA1 has not been investigated as an AF candidate gene. METHODS: The KCNMA1 gene was sequenced in 118 patients with familial AF. The role of KCa1.1 in normal cardiac structure and function was evaluated in humans, mice, zebrafish, and fly. A novel KCNMA1 variant was functionally characterized. RESULTS: A complex KCNMA1 variant was identified in 1 kindred with AF. To evaluate potential disease mechanisms, we first evaluated the distribution of KCa1.1 in normal hearts using immunostaining and immunogold electron microscopy. KCa1.1 was seen throughout the atria and ventricles in humans and mice, with strong expression in the sinus node. In an ex vivo murine sinoatrial node preparation, addition of the KCa1.1 antagonist, paxilline, blunted the increase in beating rate induced by adrenergic receptor stimulation. Knockdown of the KCa1.1 ortholog, kcnma1b, in zebrafish embryos resulted in sinus bradycardia with dilatation and reduced contraction of the atrium and ventricle. Genetic inactivation of the Drosophila KCa1.1 ortholog, slo, systemically or in adult stages, also slowed the heartbeat and produced fibrillatory cardiac contractions. Electrophysiological characterization of slo-deficient flies revealed bursts of action potentials, reflecting increased events of fibrillatory arrhythmias. Flies with cardiac-specific overexpression of the human KCNMA1 mutant also showed increased heart period and bursts of action potentials, similar to the KCa1.1 loss-of-function models. CONCLUSIONS: Our data point to a highly conserved role of KCa1.1 in sinus node function in humans, mice, zebrafish, and fly and suggest that KCa1.1 loss of function may predispose to AF.


Assuntos
Fibrilação Atrial/patologia , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta/genética , Nó Sinoatrial/metabolismo , Potenciais de Ação/efeitos dos fármacos , Animais , Fibrilação Atrial/genética , Função Atrial/efeitos dos fármacos , Função Atrial/fisiologia , Embrião não Mamífero/metabolismo , Átrios do Coração/metabolismo , Átrios do Coração/patologia , Humanos , Indóis/química , Indóis/metabolismo , Indóis/farmacologia , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta/antagonistas & inibidores , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta/metabolismo , Camundongos , Contração Miocárdica , Linhagem , Polimorfismo Genético , Interferência de RNA , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/farmacologia , Peixe-Zebra , Proteínas de Peixe-Zebra/antagonistas & inibidores , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
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