RESUMEN
BACKGROUND: Cardiac rehabilitation (CR) is an important tool for the secondary prevention of cardiac disease. Despite its proven effectiveness, CR remains vastly under-utilised especially amongst the most disadvantaged patients. As an adjunct to CR, the St Vincent's Heart Health website (SVHHH) was created by the St Vincent's Hospital CR team to provide information via simplified medical text, videos and animations. We evaluated the effectiveness of the website in educating patients about their heart condition. METHODS: Patients with a newly diagnosed cardiac condition were recruited from St Vincent's Hospital inpatient wards and outpatient clinics (n=67, age 63+/-11) and given 30minutes to interact with our online resource. Using a pre-test post-test design we evaluated the success of the website in improving patients' knowledge of their condition using a modified Brief Illness Perception Questionnaire and Patient Activation Questionnaire. RESULTS: After interacting with the website, participants rated a 50% improvement in the control they felt over their heart condition (p<0.01). Understanding of investigations, medications and management improved by 38%, 31% and 38%, respectively (all p<0.01). Subjects' understanding of their heart condition improved by 34% and confidence improved by more than 18% (p<0.01). These improvements were seen irrespective of age and primary place of residence. While older subjects had the lowest confidence using the internet, they demonstrated the greatest self-reported improvement in knowledge. There was no improvement in patients' perceived concern about their illness. CONCLUSIONS: The St Vincent's Heart Health website shows real promise as an educational tool for patients, as an adjunct to standard CR and for patients in remote settings. Online health resources will likely become an important adjunct to traditional teaching methods across all medical specialties to improve patient outcomes.
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Rehabilitación Cardiaca/métodos , Enfermedades Cardiovasculares/prevención & control , Conocimientos, Actitudes y Práctica en Salud , Recursos en Salud/tendencias , Internet , Educación del Paciente como Asunto/métodos , Prevención Secundaria/métodos , Enfermedades Cardiovasculares/diagnóstico , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Nueva Gales del Sur , Proyectos Piloto , Estudios RetrospectivosRESUMEN
AIMS: Patients with type 2 diabetes mellitus (T2DM) are known to have impaired resting myocardial energetics and impaired myocardial perfusion reserve, even in the absence of obstructive epicardial coronary artery disease (CAD). Whether or not the pre-existing energetic deficit is exacerbated by exercise, and whether the impaired myocardial perfusion causes deoxygenation and further energetic derangement during exercise stress, is uncertain. METHODS AND RESULTS: Thirty-one T2DM patients, on oral antidiabetic therapies with a mean HBA1c of 7.4 ± 1.3%, and 17 matched controls underwent adenosine stress cardiovascular magnetic resonance for assessment of perfusion [myocardial perfusion reserve index (MPRI)] and oxygenation [blood-oxygen level-dependent (BOLD) signal intensity change (SIΔ)]. Cardiac phosphorus-MR spectroscopy was performed at rest and during leg exercise. Significant CAD (>50% coronary stenosis) was excluded in all patients by coronary computed tomographic angiography. Resting phosphocreatine to ATP (PCr/ATP) was reduced by 17% in patients (1.74 ± 0.26, P = 0.001), compared with controls (2.07 ± 0.35); during exercise, there was a further 12% reduction in PCr/ATP (P = 0.005) in T2DM patients, but no change in controls. Myocardial perfusion and oxygenation were decreased in T2DM (MPRI 1.61 ± 0.43 vs. 2.11 ± 0.68 in controls, P = 0.002; BOLD SIΔ 7.3 ± 7.8 vs. 17.1 ± 7.2% in controls, P < 0.001). Exercise PCr/ATP correlated with MPRI (r = 0.50, P = 0.001) and BOLD SIΔ (r = 0.32, P = 0.025), but there were no correlations between rest PCr/ATP and MPRI or BOLD SIΔ. CONCLUSION: The pre-existing energetic deficit in diabetic cardiomyopathy is exacerbated by exercise; stress PCr/ATP correlates with impaired perfusion and oxygenation. Our findings suggest that, in diabetes, coronary microvascular dysfunction exacerbates derangement of cardiac energetics under conditions of increased workload.
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Diabetes Mellitus Tipo 2 , Circulación Coronaria , Humanos , Miocardio , Fosfocreatina , Carga de TrabajoRESUMEN
AIMS: Hypertrophic cardiomyopathy (HCM) is the commonest cause of sudden cardiac death in the young, with an excess of exercise-related deaths. The HCM sarcomere mutations increase the energy cost of contraction and impaired resting cardiac energetics has been documented by measurement of phosphocreatine/ATP (PCr/ATP) using (31)Phosphorus MR Spectroscopy ((31)P MRS). We hypothesized that cardiac energetics are further impaired acutely during exercise in HCM and that this would have important functional consequences. METHODS AND RESULTS: (31)P MRS was performed in 35 HCM patients and 20 age- and gender-matched normal volunteers at rest and during leg exercise with 2.5 kg ankle weights. Peak left-ventricular filling rates (PFRs) and myocardial perfusion reserve (MPRI) were calculated during adenosine stress. Resting PCr/ATP was significantly reduced in HCM (HCM: 1.71 ± 0.35, normal 2.14 ± 0.35 P < 0.0001). During exercise, there was a further reduction in PCr/ATP in HCM (1.56 ± 0.29, P = 0.02 compared with rest) but not in normals (2.16 ± 0.26, P = 0.98 compared with rest). There was no correlation between PCr/ATP reduction and cardiac mass, wall thickness, MPRI, or late-gadolinium enhancement. PFR and PCr/ATP were significantly correlated at rest (r = 0.48, P = 0.02) and stress (r = 0.53, P = 0.01). CONCLUSION: During exercise, the pre-existing energetic deficit in HCM is further exacerbated independent of hypertrophy, perfusion reserve, or degree of fibrosis. This is in keeping with the change at the myofilament level. We offer a potential explanation for exercise-related diastolic dysfunction in HCM.
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Cardiomiopatía Hipertrófica/metabolismo , Ejercicio Físico/fisiología , Disfunción Ventricular Izquierda/etiología , Adenosina Trifosfato/metabolismo , Adulto , Presión Sanguínea/fisiología , Estudios de Casos y Controles , Diástole , Metabolismo Energético , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Angiografía por Resonancia Magnética , Imagen por Resonancia Cinemagnética , Espectroscopía de Resonancia Magnética , Masculino , Fosfocreatina/metabolismo , Estudios Prospectivos , Volumen Sistólico/fisiología , Disfunción Ventricular Izquierda/fisiopatologíaRESUMEN
BACKGROUND: HIV infection continues to be endemic worldwide. Although treatments are successful, it remains controversial whether patients receiving optimal therapy have structural, functional, or biochemical cardiac abnormalities that may underlie their increased cardiac morbidity and mortality. The purpose of this study was to characterize myocardial abnormalities in a contemporary group of HIV-infected individuals undergoing combination antiretroviral therapy. METHODS AND RESULTS: Volunteers with HIV who were undergoing combination antiretroviral therapy and age-matched control subjects without a history of cardiovascular disease underwent cardiac magnetic resonance imaging and spectroscopy for the determination of cardiac function, myocardial fibrosis, and myocardial lipid content. A total of 129 participants were included in this analysis. Compared with age-matched control subjects (n=39; 30.23%), HIV-infected subjects undergoing combination antiretroviral therapy (n=90; 69.77%) had 47% higher median myocardial lipid levels (P <0.003) and 74% higher median plasma triglyceride levels (both P<0.001). Myocardial fibrosis, predominantly in the basal inferolateral wall of the left ventricle, was observed in 76% of HIV-infected subjects compared with 13% of control subjects (P<0.001). Peak myocardial systolic and diastolic longitudinal strain were also lower in HIV-infected individuals than in control subjects and remained statistically significant after adjustment for available confounders. CONCLUSIONS: Comprehensive cardiac imaging revealed cardiac steatosis, alterations in cardiac function, and a high prevalence of myocardial fibrosis in a contemporary group of asymptomatic HIV-infected subjects undergoing combination antiretroviral therapy. Cardiac steatosis and fibrosis may underlie cardiac dysfunction and increased cardiovascular morbidity and mortality in subjects with HIV.
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Cardiomiopatías/diagnóstico , Cardiomiopatías/epidemiología , Infecciones por VIH/complicaciones , Imagen por Resonancia Magnética , Espectroscopía de Resonancia Magnética , Adulto , Antirretrovirales/uso terapéutico , Cardiomiopatías/patología , Estudios de Casos y Controles , Estudios Transversales , Femenino , Fibrosis , Infecciones por VIH/tratamiento farmacológico , Corazón/fisiopatología , Humanos , Metabolismo de los Lípidos/fisiología , Masculino , Persona de Mediana Edad , Miocardio/metabolismo , Miocardio/patología , PrevalenciaRESUMEN
OBJECTIVE: As inspired oxygen availability falls with ascent to altitude, some individuals develop high-altitude headache (HAH). We postulated that HAH results when hypoxia-associated increases in cerebral blood flow occur in the context of restricted venous drainage, and is worsened when cerebral compliance is reduced. We explored this hypothesis in 3 studies. METHODS: In high-altitude studies, retinal venous distension (RVD) was ophthalmoscopically assessed in 24 subjects (6 female) and sea-level cranial magnetic resonance imaging was performed in 12 subjects ascending to 5,300m. Correlation of headache burden (summed severity scores [0-4]≤24 hours from arrival at each altitude) with RVD, and with cerebral/cerebrospinal fluid (CSF)/venous compartment volumes, was sought. In a sea-level hypoxic study, 11 subjects underwent gadolinium-enhanced magnetic resonance venography before and during hypoxic challenge (fraction of inspired oxygen=0.11, 1 hour). RESULTS: In the high-altitude studies, headache burden correlated with both RVD (Spearman rho=0.55, p=0.005) and with the degree of narrowing of 1 or both transverse venous sinuses (r=-0.56, p=0.03). It also related inversely to both the lateral+third ventricle summed volumes (Spearman rho=-0.5, p=0.05) and pericerebellar CSF volume (r=-0.56, p=0.03). In the hypoxic study, cerebral and retinal vein engorgement were correlated, and rose as the combined conduit score fell (a measure of venous outflow restriction; r=-0.66, p<0.05 and r=-0.75, p<0.05, respectively). INTERPRETATION: Arterial hypoxemia is associated with cerebral and retinal venous distension, whose magnitude correlates with HAH burden. Restriction in cerebral venous outflow is associated with retinal distension and HAH. Limitations in cerebral venous efferent flow may predispose to headache when hypoxia-related increases in cerebral arterial flow occur.
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Altitud , Venas Cerebrales/patología , Venas Cerebrales/fisiopatología , Circulación Cerebrovascular/fisiología , Cefalea/etiología , Cefalea/patología , Adulto , Anciano , Causalidad , Estudios de Cohortes , Femenino , Humanos , Hipoxia/metabolismo , Angiografía por Resonancia Magnética , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Retina/patología , Índice de Severidad de la Enfermedad , Adulto JovenRESUMEN
BACKGROUND: Patients with treated Human Immunodeficiency Virus-1 (HIV) infection are at increased risk of cardiovascular events. Traditionally much of this risk has been attributed to metabolic and anthropometric abnormalities associated with HIV, which are similar to the metabolic syndrome (MS), an established risk factor for cardiovascular mortality. It remains unclear whether treated HIV infection is itself associated with increased risk, via increase vascular stiffness. METHODS: 226 subjects (90 with HIV) were divided into 4 groups based on HIV and MS status: 1) HIV-ve/MS-ve, 2) HIV-ve/MS + ve, 3) HIV + ve/MS-ve and 4)HIV + ve/MS + ve. CMR was used to determine aortic pulse wave velocity (PWV) and regional aortic distensibility (AD). RESULTS: PWV was 11% higher and regional AD up to 14% lower in the HIV + ve/MS-ve group when compared to HIV-ve/MS-ve (p < 0.01 all analyses). PWV and AD in the HIV + ve/MS-ve group was similar to that observed in the HIV-ve/MS + ve group (p > 0.99 all analyses). The HIV + ve/MS + ve group had 32% higher PWV and 30-34% lower AD than the HIV-ve/MS-ve group (all p < 0.001), and 19% higher PWV and up to 31% lower AD than HIV + ve/MS-ve subjects (all p < 0.05). On multivariable regression, age, systolic blood pressure and treated HIV infection were all independent predictors of both PWV and regional AD. CONCLUSION: Across multiple measures, treated HIV infection is associated with increased aortic stiffness and is also an independent predictor of both PWV and regional AD. The magnitude of the effect of treated HIV and MS are similar, with additive detrimental effects on central vascular elasticity.
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Enfermedades Cardiovasculares/fisiopatología , Infecciones por VIH/complicaciones , Rigidez Vascular , Adulto , Factores de Edad , Terapia Antirretroviral Altamente Activa , Presión Sanguínea , Enfermedades Cardiovasculares/diagnóstico , Enfermedades Cardiovasculares/virología , Estudios de Casos y Controles , Infecciones por VIH/diagnóstico , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/virología , VIH-1/patogenicidad , Humanos , Imagen por Resonancia Cinemagnética , Síndrome Metabólico/diagnóstico , Síndrome Metabólico/terapia , Síndrome Metabólico/virología , Persona de Mediana Edad , Análisis Multivariante , Valor Predictivo de las Pruebas , Análisis de la Onda del Pulso , Factores de RiesgoRESUMEN
BACKGROUND: Cardiovascular magnetic resonance (CMR) is regarded as the gold standard for clinical assessment of the aorta, but normal dimensions are usually referenced to echocardiographic and computed tomography data and no large CMR normal reference range exists. As a result we aimed to 1) produce a normal CMR reference range of aortic diameters and 2) investigate the relationship between regional aortic size and body surface area (BSA) in a large group of healthy subjects with no vascular risk factors. METHODS: 447 subjects (208 male, aged 19-70 years) without identifiable cardiac risk factors (BMI range 15.7-52.6 kg/m2) underwent CMR at 1.5 T to determine aortic diameter at three levels: the ascending aorta (Ao) and proximal descending aorta (PDA) at the level of the pulmonary artery, and the abdominal aorta (DDA), at a level 12 cm distal to the PDA. In addition, 201 of these subjects had aortic root imaging, allowing for measurements at the level of the aortic valve annulus (AV), aortic sinuses and sinotubular junction (STJ). RESULTS: Normal diameters (mean ±2 SD) were; AV annulus male(â) 24.4 ± 5.4, female (â) 21.0 ± 3.6 mm, aortic sinusâ 32.4 ± 7.7, â27.6 ± 5.8 mm, ST-junction â25.0 ± 7.4, â21.8 ± 5.4 mm, Ao â26.7 ± 7.7, â25.5 ± 7.4 mm, PDA â20.6 ± 5.6, +18.9 ± 4.0 mm, DDA â17.6 ± 5.1, â16.4 ± 4.0 mm. Aortic root and thoracic aortic diameters increased at all levels measured with BSA. No gender difference was seen in the degree of dilatation with increasing BSA (p>0.5 for all analyses). CONCLUSION: Across both genders, increasing body size is characterized by a modest degree of aortic dilatation, even in the absence of traditional cardiovascular risk factors.
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Aorta/patología , Aneurisma de la Aorta/etiología , Tamaño Corporal , Imagen por Resonancia Magnética , Nomogramas , Obesidad/complicaciones , Adulto , Factores de Edad , Anciano , Aneurisma de la Aorta/patología , Índice de Masa Corporal , Superficie Corporal , Estudios Transversales , Dilatación Patológica , Femenino , Humanos , Imagen por Resonancia Magnética/normas , Masculino , Persona de Mediana Edad , Obesidad/diagnóstico , Variaciones Dependientes del Observador , Valor Predictivo de las Pruebas , Valores de Referencia , Reproducibilidad de los Resultados , Factores Sexuales , Adulto JovenRESUMEN
AIMS: As obesity-related cardiovascular mortality, although elevated when compared with normal weight, is lower in females than in males at every body mass index (BMI) level, we aimed to investigate gender-specific differences in left ventricular (LV) hypertrophy in obesity, which themselves have been shown to have varying prognostic value. METHOD AND RESULTS: In total, 741 subjects (female, n = 399) without identifiable cardiovascular risk factors (BMI 15.7-59.2 kg/m(2)) underwent cardiovascular magnetic resonance (1.5 T) to determine LV mass, end-diastolic volume (EDV, mL), and LV mass/volume ratio (LVM/VR). Across both sexes, there was a strong positive correlation between BMI and LV mass (male r = 0.44, female r = 0.57, both P < 0.001), with males showing a greater LV hypertrophic response (male +2.3 vs. female +1.6 g per BMI point increase, P = 0.001). Concentric hypertrophy was present in both sexes and LVM/VR positively correlated to BMI (male r = 0.45, female r = 0.29, both P < 0.001) on linear regression analysis. However, the degree of concentric hypertrophy was greater in males (male +0.13 vs. female +0.06 LVM/VR increase per BMI point increase, P = 0.001). On the other hand, females showed a greater LV cavity dilatory response (female +1.1 vs. male +0.3 mL per BMI point increase, P < 0.001). Indeed, in contrast to females, where BMI and LV-EDV were positively correlated (r = 0.38, P < 0.001), BMI did not correlate with EDV in men (r = 0.03, P = 0.62). CONCLUSION: In the absence of traditional cardiovascular risk factors, obese men show predominantly concentric hypertrophy, whereas obese women exhibit both eccentric and concentric hypertrophy. As concentric hypertrophy is more strongly related to cardiovascular mortality than eccentric hypertrophy, our observations may explain the observed gender difference in obesity-related mortality.
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Obesidad/fisiopatología , Remodelación Ventricular/fisiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Índice de Masa Corporal , Femenino , Humanos , Hipertrofia Ventricular Izquierda/patología , Hipertrofia Ventricular Izquierda/fisiopatología , Angiografía por Resonancia Magnética , Masculino , Persona de Mediana Edad , Obesidad/patología , Caracteres Sexuales , Volumen Sistólico/fisiología , Función Ventricular Izquierda/fisiología , Adulto JovenAsunto(s)
Angiografía Coronaria/métodos , Anomalías de los Vasos Coronarios , Vasos Coronarios/diagnóstico por imagen , Enfermedades Vasculares/congénito , Procedimientos Quirúrgicos Vasculares/métodos , Causas de Muerte/tendencias , Anomalías de los Vasos Coronarios/diagnóstico , Anomalías de los Vasos Coronarios/epidemiología , Anomalías de los Vasos Coronarios/cirugía , Vasos Coronarios/cirugía , Salud Global , Humanos , Incidencia , Tasa de Supervivencia/tendencias , Enfermedades Vasculares/diagnóstico , Enfermedades Vasculares/epidemiología , Enfermedades Vasculares/cirugíaRESUMEN
We recently showed that a short-term high-fat diet blunted exercise performance in rats, accompanied by increased uncoupling protein levels and greater respiratory uncoupling. In this study, we investigated the effects of a similar diet on physical and cognitive performance in humans. Twenty sedentary men were assessed when consuming a standardized, nutritionally balanced diet (control) and after 7 d of consuming a diet comprising 74% kcal from fat. Efficiency was measured during a standardized exercise task, and cognition was assessed using a computerized assessment battery. Skeletal muscle mitochondrial function was measured using (31)P magnetic resonance spectroscopy. The diet increased mean ± se plasma free fatty acids by 44% (0.32±0.03 vs. 0.46±0.05 mM; P<0.05) and decreased whole-body efficiency by 3% (21±1 vs. 18±1%; P<0.05), although muscle uncoupling protein (UCP3) content and maximal mitochondrial function were unchanged. High-fat diet consumption also increased subjects' simple reaction times (P<0.01) and decreased power of attention (P<0.01). Thus, we have shown that a high-fat diet blunts whole-body efficiency and cognition in sedentary men. We suggest that this effect may be due to increased respiratory uncoupling.
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Cognición/fisiología , Grasas de la Dieta/efectos adversos , Metabolismo Energético/fisiología , Ejercicio Físico/fisiología , Mitocondrias/metabolismo , Adulto , Grasas de la Dieta/farmacocinética , Prueba de Esfuerzo , Humanos , Canales Iónicos/metabolismo , Espectroscopía de Resonancia Magnética , Masculino , Persona de Mediana Edad , Proteínas Mitocondriales/metabolismo , Modelos Biológicos , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Consumo de Oxígeno/fisiología , Fósforo/metabolismo , Conducta Sedentaria , Proteína Desacopladora 3RESUMEN
We postulated that changes in cardiac high-energy phosphate metabolism may underlie the myocardial dysfunction caused by hypobaric hypoxia. Healthy volunteers (n=14) were studied immediately before, and within 4 d of return from, a 17-d trek to Mt. Everest Base Camp (5300 m). (31)P magnetic resonance (MR) spectroscopy was used to measure cardiac phosphocreatine (PCr)/ATP, and MR imaging and echocardiography were used to assess cardiac volumes, mass, and function. Immediately after returning from Mt. Everest, total body weight had fallen by 3% (P<0.05), but left ventricular mass, adjusted for changes in body surface area, had disproportionately decreased by 11% (P<0.05). Alterations in diastolic function were also observed, with a reduction in peak left ventricular filling rates and mitral inflow E/A, by 17% (P<0.05) and 24% (P<0.01), respectively, with no change in hydration status. Compared with pretrek, cardiac PCr/ATP ratio had decreased by 18% (P<0.01). Whether the abnormalities were even greater at altitude is unknown, but all had returned to pretrek levels after 6 mo. The alterations in cardiac morphology, function, and energetics are similar to findings in patients with chronic hypoxia. Thus, a decrease in cardiac PCr/ATP may be a universal response to periods of sustained low oxygen availability, underlying hypoxia-induced cardiac dysfunction in healthy human heart and in patients with cardiopulmonary diseases.
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Altitud , Metabolismo Energético/fisiología , Ventrículos Cardíacos/anatomía & histología , Miocardio/metabolismo , Función Ventricular/fisiología , Aclimatación , Adulto , Femenino , Humanos , Masculino , Montañismo , Tamaño de los Órganos , Fosfatos/metabolismoRESUMEN
Pulmonary hypertension (PH) is characterized by progressive dyspnea, fatigue, and reduced exercise capacity. Despite medical treatment, outcomes remain poor. While exercise training is well established in patients with heart failure, it is less established in patients with PH. This single-blind, randomized controlled pilot study examined the feasibility and effect of 12-week outpatient exercise (multidisciplinary rehabilitation or home walking program) on hemodynamics using cardiac magnetic resonance imaging (cMRI) and right heart catheterization (RHC) in patients with pulmonary arterial hypertension (PAH), a subset of PH. Sixteen participants were randomized to either multidisciplinary outpatient rehabilitation or a home walking program for 12 weeks. Primary outcome measures were changes in right ventricular ejection fraction and stroke volume index on cMRI. Secondary outcome measures included hemodynamics on RHC, quality of life (QOL), muscle strength (handgrip and vital capacity) and 6-min walk test. This preliminary, pilot study suggests that outpatient exercise interventions may be associated with improved hemodynamic function (mean pulmonary artery wedge pressure, stroke volume, and stroke volume index), QOL (PH symptoms, depression, and anxiety), and muscular strength (vital capacity and handgrip strength) for people with PAH, but was not adequately powered to make any formal conclusions. However, our outpatient programs were feasible, safe, and acceptable to participants. Future studies are required to further explore the potential hemodynamic benefits of exercise in PAH.
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We recently showed that a week-long, high-fat diet reduced whole body exercise efficiency in sedentary men by >10% (Edwards LM, Murray AJ, Holloway CJ, Carter EE, Kemp GJ, Codreanu I, Brooker H, Tyler DJ, Robbins PA, Clarke K. FASEB J 25: 1088-1096, 2011). To test if a similar dietary regime would blunt whole body efficiency in endurance-trained men and, as a consequence, hinder aerobic exercise performance, 16 endurance-trained men were given a short-term, high-fat (70% kcal from fat) and a moderate carbohydrate (50% kcal from carbohydrate) diet, in random order. Efficiency was assessed during a standardized exercise task on a cycle ergometer, with aerobic performance assessed during a 1-h time trial and mitochondrial function later measured using (31)P-magnetic resonance spectroscopy. The subjects then underwent a 2-wk wash-out period, before the study was repeated with the diets crossed over. Muscle biopsies, for mitochondrial protein analysis, were taken at the start of the study and on the 5th day of each diet. Plasma fatty acids were 60% higher on the high-fat diet compared with moderate carbohydrate diet (P < 0.05). However, there was no change in whole body efficiency and no change in mitochondrial function. Endurance exercise performance was significantly reduced (P < 0.01), most probably due to glycogen depletion. Neither diet led to changes in citrate synthase, ATP synthase, or mitochondrial uncoupling protein 3. We conclude that prior exercise training blunts the deleterious effect of short-term, high-fat feeding on whole body efficiency.
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Grasas de la Dieta/efectos adversos , Metabolismo Energético/efectos de los fármacos , Resistencia Física/fisiología , Grasas de la Dieta/administración & dosificación , Ejercicio Físico , Ácidos Grasos/sangre , Humanos , Masculino , Mitocondrias Musculares/metabolismo , Adulto JovenRESUMEN
INTRODUCTION: Adenosine is the most widely used vasodilator stress agent for cardiovascular magnetic resonance (CMR) perfusion studies. With the standard dose of 140 mcg/kg/min some patients fail to demonstrate characteristic haemodynamic changes: a significant increase in heart rate (HR) and mild decrease in systolic blood pressure (SBP). Whether an increase in the rate of adenosine infusion would improve peripheral and, likely, coronary vasodilatation in those patients is unknown. The aim of the present study was to assess the tolerance and safety of a high-dose adenosine protocol in patients with inadequate haemodynamic response to the standard adenosine protocol when undergoing CMR perfusion imaging. METHODS: 98 consecutive patients with known or suspected coronary artery disease (CAD) underwent CMR perfusion imaging at 1.5 Tesla. Subjects were screened for contraindications to adenosine, and an electrocardiogram was performed prior to the scan. All patients initially received the standard adenosine protocol (140 mcg/kg/min for at least 3 minutes). If the haemodynamic response was inadequate (HR increase < 10 bpm or SBP decrease < 10 mmHg) then the infusion rate was increased up to a maximum of 210 mcg/kg/min (maximal infusion duration 7 minutes). RESULTS: All patients successfully completed the CMR scan. Of a total of 98 patients, 18 (18%) did not demonstrate evidence of a significant increase in HR or decrease in SBP under the standard adenosine infusion rate. Following the increase in the rate of infusion, 16 out of those 18 patients showed an adequate haemodynamic response. One patient of the standard infusion group and two patients of the high-dose group developed transient advanced AV block. Significantly more patients complained of chest pain in the high-dose group (61% vs. 29%, p = 0.009). On multivariate analysis, age > 65 years and ejection fraction < 57% were the only independent predictors of blunted haemodynamic responsiveness to adenosine. CONCLUSIONS: A substantial number of patients do not show adequate peripheral haemodynamic response to standard-dose adenosine stress during perfusion CMR imaging. Age and reduced ejection fraction are predictors of inadequate response to standard dose adenosine. A high-dose adenosine protocol (up to 210 mcg/kg/min) is well tolerated and results in adequate haemodynamic response in nearly all patients.
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Adenosina , Enfermedad de la Arteria Coronaria/diagnóstico , Circulación Coronaria/efectos de los fármacos , Hemodinámica/efectos de los fármacos , Imagen por Resonancia Magnética , Imagen de Perfusión Miocárdica/métodos , Vasodilatadores , Adenosina/administración & dosificación , Adenosina/efectos adversos , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Bloqueo Atrioventricular/inducido químicamente , Presión Sanguínea/efectos de los fármacos , Dolor en el Pecho/inducido químicamente , Distribución de Chi-Cuadrado , Enfermedad de la Arteria Coronaria/fisiopatología , Relación Dosis-Respuesta a Droga , Electrocardiografía , Inglaterra , Estudios de Factibilidad , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Infusiones Intravenosas , Modelos Logísticos , Imagen por Resonancia Magnética/efectos adversos , Masculino , Persona de Mediana Edad , Imagen de Perfusión Miocárdica/efectos adversos , Valor Predictivo de las Pruebas , Medición de Riesgo , Factores de Riesgo , Volumen Sistólico , Vasodilatación/efectos de los fármacos , Vasodilatadores/administración & dosificación , Vasodilatadores/efectos adversos , Adulto JovenRESUMEN
OBJECTIVE: Using high resolution cardiovascular magnetic resonance (CMR), we aimed to detect new details of left ventricular (LV) systolic and diastolic function, to explain the twisting and longitudinal movements of the left ventricle. METHODS: Using CMR phase contrast velocity mapping (also called Tissue Phase Mapping) regional wall motion patterns and longitudinally and circumferentially directed movements of the left ventricle were studied using a high temporal resolution technique in healthy male subjects (n = 14, age 23 +/- 3 years). RESULTS: Previously undescribed systolic and diastolic motion patterns were obtained for left ventricular segments (based on the AHA segmental) and for basal, mid and apical segments. The summation of segmental motion results in a complex pattern of ventricular twisting and longitudinal motion in the normal human heart which underlies systolic and diastolic function. As viewed from the apex, the entire LV initially rotates in a counter-clockwise direction at the beginning of ventricular systole, followed by opposing clockwise rotation of the base and counter-clockwise rotation at the apex, resulting in ventricular torsion. Simultaneously, as the entire LV moves in an apical direction during systole, the base and apex move towards each other, with little net apical displacement. The reverse of these motion patterns occur in diastole. CONCLUSION: Left ventricular function may be a consequence of the relative orientations and moments of torque of the sub-epicardial relative to the sub-endocardial myocyte layers, with influence from tethering of the heart to adjacent structures and the directional forces associated with blood flow. Understanding the complex mechanics of the left ventricle is vital to enable these techniques to be used for the evaluation of cardiac pathology.
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Imagen por Resonancia Magnética/métodos , Función Ventricular Izquierda/fisiología , Adulto , Diástole/fisiología , Humanos , Masculino , Sístole/fisiologíaRESUMEN
Cardiovascular magnetic resonance (CMR) has increasingly become a powerful imaging technique over the past few decades due to increasing knowledge about clinical applications, operator experience and technological advances, including the introduction of high field strength magnets, leading to improved signal-to-noise ratio. Its success is attributed to the free choice of imaging planes, the wide variety of imaging techniques, and the lack of harmful radiation. Developments in CMR have led to the accurate evaluation of cardiac structure, function and tissues characterisation, so this non-invasive technique has become a powerful tool for a broad range of cardiac pathologies. This review will provide an introduction of magnetic resonance imaging (MRI) physics, an overview of the current techniques and clinical application of CMR in structural heart disease, and illustrated examples of its use in clinical practice.
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BACKGROUND: Mobile valvular masses are often considered pathognomonic for infective endocarditis. We present a case of a young patient with mobile valvular masses in the context of myocarditis likely secondary to active ileal Crohn's disease. Cardiac magnetic resonance (CMR) imaging was crucial in diagnosing and monitoring our patient. CASE SUMMARY: A 27-year-old woman presented with pleuritic chest pain, dyspnoea, and a 3-day history of fevers. She also reported a 2-month history of intermittent visual loss in her right eye. She had a history of histologically proven ileal Crohn's disease, diagnosed 5 months prior. She was haemodynamically unstable on presentation. Abnormalities on a transthoracic echocardiogram necessitated a transoesophageal echocardiogram. After blood cultures were sent, the patient was commenced on empirical treatment for infective endocarditis with gentamicin and flucloxacillin. Eight days after her initial presentation, all blood cultures remained negative and she was changed to empirical treatment for culture negative endocarditis with ceftriaxone and vancomycin, according to local protocol. Despite 8 days of treatment for infective endocarditis she remained febrile. A CMR was organized on Day 9 and this showed myocarditis, which changed the treatment paradigm. She responded swiftly to steroids and anti-coagulation. DISCUSSION: In this case, echo-dense valvular lesions are not pathognomonic for infective endocarditis and a careful diagnostic process involving multi-modality imaging, including CMR, occurred to arrive at a diagnosis of myocarditis likely secondary to Crohn's disease.
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Although people living with HIV (PLHIV) are approaching normal life expectancy, a limitation to achieving this goal is managing the higher prevalence of co-morbidities, including cardiovascular disease. Whilst ischaemic heart disease likely contributes to a large proportion of cardiac disease in the modern era of treatment, cardio-metabolic disease, including cardiac steatosis, akin to obesity-related heart disease, is also a possible mechanism of increased cardiac morbidity and mortality. HIV and other metabolic and inflammatory diseases affecting the heart, including obesity, share many cardio-metabolic abnormalities, with increased pericardial and myocardial fat content, in association with chronic systemic inflammatory changes and alterations in cardiac metabolism. Understanding the mechanisms of HIV-associated cardiac steatosis remains an important challenge, as managing the untreated metabolic and inflammatory precipitants may substantially improve cardiac outcomes for PLHIV.
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Cardiovascular disease (CVD) has a higher incidence in patients with HIV infection. This study sought to determine whether HIV-infected patients with established CVD were being managed according to national guidelines. Data were collected from Australian general practitioners for 77 HIV-infected patients with a median age of 59 (range 54-64). There was good adherence to guidelines with regards to anti-platelet (84%; n=65; 95% confidence interval (CI) 74-92%) and statin therapy (97%; n=75; 95% CI 91-100%), despite a failure to meet cholesterol targets, with only 31% (n=24; 95% CI 21-42%) of the cohort meeting low-density lipoprotein target values. Similarly, there was limited adherence to guidelines regarding the prescriptions of medications for those with established hypertension (66%; n=51; 95% CI 55-77%), body mass index targets met (40%; n=31; 95% CI 29-52%), and depression screening (32%; n=25; 95% CI 22-44%). This Australian audit provides insight into adherence to guidelines for individuals with CVD and HIV, suggesting that current screening and management practices for these patients falls short of guidelines, particularly in relation to cholesterol management.