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1.
J Cardiovasc Magn Reson ; 24(1): 36, 2022 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-35692049

RESUMO

BACKGROUND: The right ventricle (RV) in hypertrophic cardiomyopathy (HCM) tends to be neglected, as previous efforts have predominantly focused on examining the prognostic value of left ventricular (LV) abnormalities. The objectives of this study were to assess RV function in HCM, changes over time, and association with clinical outcomes. METHODS: Two hundred and ninety HCM patients with preserved LV ejection fraction (LVEF ≥ 55%) and 30 age- and sex-matched controls underwent cardiovascular magnetic resonance (CMR). All patients were followed up for clinical events for a median duration of 4.4 years. Sixty-three patients had a follow-up CMR undertaken at a median interval of 5.4 years. Main study measures and outcomes were RV function (RV ejection fraction (RVEF) and RV strain) at baseline, temporal changes in RV function over time and prognostic value of RV dysfunction for predicting cardiovascular outcomes in HCM. RESULTS: When compared to controls, HCM patients exhibited lower RV and LV peak global longitudinal systolic strains on feature-tracking analysis of cine images, while RVEF and LVEF were within the normal range. On follow-up CMR, both RV and LV strain parameters decreased over time. RVEF decreased at follow-up (65 ± 7% to 62 ± 7%, P < 0.001) but the change in LVEF was not significant (68 ± 10% to 66 ± 8%, P = 0.30). On clinical follow up, reduced RVEF was an independent predictor of non-sustained ventricular tachycardia (NSVT) [HR 1.10 (95% CI 1.06-1.15), P < 0.001] and composite cardiovascular events (NSVT, stroke, heart failure hospitalisation and cardiovascular death) [HR 1.07 (95% CI 1.03-1.10), P < 0.001]. RV longitudinal strain was an independent predictor of NSVT [HR 1.05 (95% CI 1.01-1.09), P = 0.029]. Patients with RVEF < 55% showed an increased risk of NSVT and composite cardiovascular events. In contrast, LVEF and LV global longitudinal strain were not predictive of such events on multivariable analysis. CONCLUSIONS: In HCM, RV function, including RV strain, and LV strain decrease over time despite preserved LVEF. Reduction in RV but not LV function is associated with adverse cardiovascular outcomes. Assessing RV function in early HCM disease might have a role in risk stratification to prevent future cardiovascular events.


Assuntos
Cardiomiopatia Hipertrófica , Função Ventricular Direita , Cardiomiopatia Hipertrófica/complicações , Cardiomiopatia Hipertrófica/diagnóstico por imagem , Humanos , Imagem Cinética por Ressonância Magnética/métodos , Valor Preditivo dos Testes , Volume Sistólico , Função Ventricular Esquerda
2.
J Cardiovasc Magn Reson ; 20(1): 88, 2018 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-30580760

RESUMO

BACKGROUND: Heart failure (HF) is characterized by altered myocardial substrate metabolism which can lead to myocardial triglyceride accumulation (steatosis) and lipotoxicity. However its role in mild HF with preserved ejection fraction (HFpEF) is uncertain. We measured myocardial triglyceride content (MTG) in HFpEF and assessed its relationships with diastolic function and exercise capacity. METHODS: Twenty seven HFpEF (clinical features of HF, left ventricular EF >50%, evidence of mild diastolic dysfunction and evidence of exercise limitation as assessed by cardiopulmonary exercise test) and 14 controls underwent 1H-cardiovascular magnetic resonance spectroscopy (1H-CMRS) to measure MTG (lipid/water, %), 31P-CMRS to measure myocardial energetics (phosphocreatine-to-adenosine triphosphate - PCr/ATP) and feature-tracking cardiovascular magnetic resonance (CMR) imaging for diastolic strain rate. RESULTS: When compared to controls, HFpEF had 2.3 fold higher in MTG (1.45 ± 0.25% vs. 0.64 ± 0.16%, p = 0.009) and reduced PCr/ATP (1.60 ± 0.09 vs. 2.00 ± 0.10, p = 0.005). HFpEF had significantly reduced diastolic strain rate and maximal oxygen consumption (VO2 max), which both correlated significantly with elevated MTG and reduced PCr/ATP. On multivariate analyses, MTG was independently associated with diastolic strain rate while diastolic strain rate was independently associated with VO2 max. CONCLUSIONS: Myocardial steatosis is pronounced in mild HFpEF, and is independently associated with impaired diastolic strain rate which is itself related to exercise capacity. Steatosis may adversely affect exercise capacity by indirect effect occurring via impairment in diastolic function. As such, myocardial triglyceride may become a potential therapeutic target to treat the increasing number of patients with HFpEF.


Assuntos
Metabolismo Energético , Tolerância ao Exercício , Insuficiência Cardíaca/diagnóstico por imagem , Imagem Cinética por Ressonância Magnética , Contração Miocárdica , Miocárdio/metabolismo , Triglicerídeos/metabolismo , Função Ventricular Esquerda , Trifosfato de Adenosina/metabolismo , Idoso , Biomarcadores/metabolismo , Fenômenos Biomecânicos , Estudos de Casos e Controles , Teste de Esforço , Feminino , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Miocárdio/patologia , Consumo de Oxigênio , Fosfocreatina/metabolismo , Valor Preditivo dos Testes , Estudos Prospectivos , Espectroscopia de Prótons por Ressonância Magnética , Índice de Gravidade de Doença
3.
Eur Heart J ; 36(24): 1547-54, 2015 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-25990345

RESUMO

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.


Assuntos
Cardiomiopatia Hipertrófica/metabolismo , Exercício Físico/fisiologia , Disfunção Ventricular Esquerda/etiologia , Trifosfato de Adenosina/metabolismo , Adulto , Pressão Sanguínea/fisiologia , Estudos de Casos e Controles , Diástole , Metabolismo Energético , Feminino , Frequência Cardíaca/fisiologia , Humanos , Angiografia por Ressonância Magnética , Imagem Cinética por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Masculino , Fosfocreatina/metabolismo , Estudos Prospectivos , Volume Sistólico/fisiologia , Disfunção Ventricular Esquerda/fisiopatologia
4.
J Cardiovasc Magn Reson ; 16: 92, 2014 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-25410203

RESUMO

BACKGROUND: Myocardial T1 relaxation times have been reported to be markedly abnormal in diverse myocardial pathologies, ascribed to interstitial changes, evaluated by T1 mapping and calculation of extracellular volume (ECV). T1 mapping is sensitive to myocardial water content of both intra- and extracellular in origin, but the effect of intravascular compartment changes on T1 has been largely neglected. We aimed to assess the role of intravascular compartment on native (pre-contrast) T1 values by studying the effect of adenosine-induced vasodilatation in patients with severe aortic stenosis (AS) before and after aortic valve replacement (AVR). METHODS: 42 subjects (26 patients with severe AS without obstructive coronary artery disease and 16 controls) underwent cardiovascular magnetic resonance at 3 T for native T1-mapping (ShMOLLI), first-pass perfusion (myocardial perfusion reserve index-MPRI) at rest and during adenosine stress, and late gadolinium enhancement (LGE). RESULTS: AS patients had increased resting myocardial T1 (1196±47 ms vs. 1168±27 ms, p=0.037), reduced MPRI (0.92±0.31 vs. 1.74±0.32, p<0.001), and increased left ventricular mass index (LVMI) and LGE volume compared to controls. During adenosine stress, T1 in AS was similar to controls (1240±51 ms vs. 1238±54 ms, p=0.88), possibly reflecting a similar level of maximal coronary vasodilatation in both groups. Conversely, the T1 response to stress was blunted in AS (ΔT1 3.7±2.7% vs. 6.0±4.2% in controls, p=0.013). Seven months after AVR (n=16) myocardial T1 and response to adenosine stress recovered towards normal. Native T1 values correlated with reduced MPRI, aortic valve area, and increased LVMI. CONCLUSIONS: Our study suggests that native myocardial T1 values are not only influenced by interstitial and intracellular water changes, but also by changes in the intravascular compartment. Performing T1 mapping during or soon after vasodilator stress may affect ECV measurements given that hyperemia alone appears to substantially alter T1 values.


Assuntos
Adenosina , Estenose da Valva Aórtica/diagnóstico , Circulação Coronária , Imagem Cinética por Ressonância Magnética/métodos , Contração Miocárdica , Imagem de Perfusão do Miocárdio/métodos , Vasodilatação , Vasodilatadores , Função Ventricular Esquerda , Idoso , Valva Aórtica/fisiopatologia , Valva Aórtica/cirurgia , Estenose da Valva Aórtica/patologia , Estenose da Valva Aórtica/fisiopatologia , Estenose da Valva Aórtica/cirurgia , Estudos de Casos e Controles , Meios de Contraste , Feminino , Fibrose , Gadolínio DTPA , Implante de Prótese de Valva Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Miocárdio/patologia , Valor Preditivo dos Testes , Estudos Prospectivos , Índice de Gravidade de Doença , Resultado do Tratamento
5.
J Cardiovasc Magn Reson ; 16: 29, 2014 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-24779370

RESUMO

BACKGROUND: Left ventricular (LV) hypertrophy in aortic stenosis (AS) is characterized by reduced myocardial perfusion reserve due to coronary microvascular dysfunction. However, whether this hypoperfusion leads to tissue deoxygenation is unknown. We aimed to assess myocardial oxygenation in severe AS without obstructive coronary artery disease, and to investigate its association with myocardial energetics and function. METHODS: Twenty-eight patients with isolated severe AS and 15 controls underwent cardiovascular magnetic resonance (CMR) for assessment of perfusion (myocardial perfusion reserve index-MPRI) and oxygenation (blood-oxygen level dependent-BOLD signal intensity-SI change) during adenosine stress. LV circumferential strain and phosphocreatine/adenosine triphosphate (PCr/ATP) ratios were assessed using tagging CMR and 31P MR spectroscopy, respectively. RESULTS: AS patients had reduced MPRI (1.1 ± 0.3 vs. controls 1.7 ± 0.3, p < 0.001) and BOLD SI change during stress (5.1 ± 8.9% vs. controls 18.2 ± 10.1%, p = 0.001), as well as reduced PCr/ATP (1.45 ± 0.21 vs. 2.00 ± 0.25, p < 0.001) and LV strain (-16.4 ± 2.7% vs. controls -21.3 ± 1.9%, p < 0.001). Both perfusion reserve and oxygenation showed positive correlations with energetics and LV strain. Furthermore, impaired energetics correlated with reduced strain. Eight months post aortic valve replacement (AVR) (n = 14), perfusion (MPRI 1.6 ± 0.5), oxygenation (BOLD SI change 15.6 ± 7.0%), energetics (PCr/ATP 1.86 ± 0.48) and circumferential strain (-19.4 ± 2.5%) improved significantly. CONCLUSIONS: Severe AS is characterized by impaired perfusion reserve and oxygenation which are related to the degree of derangement in energetics and associated LV dysfunction. These changes are reversible on relief of pressure overload and hypertrophy regression. Strategies aimed at improving oxygen demand-supply balance to preserve myocardial energetics and LV function are promising future therapies.


Assuntos
Estenose da Valva Aórtica/diagnóstico , Circulação Coronária , Metabolismo Energético , Hipertrofia Ventricular Esquerda/diagnóstico , Imagem Cinética por Ressonância Magnética , Imagem de Perfusão do Miocárdio/métodos , Miocárdio/metabolismo , Consumo de Oxigênio , Disfunção Ventricular Esquerda/diagnóstico , Função Ventricular Esquerda , Adenosina , Trifosfato de Adenosina/metabolismo , Idoso , Estenose da Valva Aórtica/complicações , Estenose da Valva Aórtica/metabolismo , Estenose da Valva Aórtica/fisiopatologia , Biomarcadores/metabolismo , Estudos de Casos e Controles , Feminino , Humanos , Hipertrofia Ventricular Esquerda/etiologia , Hipertrofia Ventricular Esquerda/metabolismo , Hipertrofia Ventricular Esquerda/fisiopatologia , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Fosfocreatina/metabolismo , Valor Preditivo dos Testes , Índice de Gravidade de Doença , Vasodilatadores , Disfunção Ventricular Esquerda/etiologia , Disfunção Ventricular Esquerda/metabolismo , Disfunção Ventricular Esquerda/fisiopatologia
6.
Eur Heart J ; 34(4): 292-9, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23053174

RESUMO

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.


Assuntos
Obesidade/fisiopatologia , Remodelação Ventricular/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Feminino , Humanos , Hipertrofia Ventricular Esquerda/patologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Angiografia por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Obesidade/patologia , Caracteres Sexuais , Volume Sistólico/fisiologia , Função Ventricular Esquerda/fisiologia , Adulto Jovem
7.
Eur Heart J Cardiovasc Imaging ; 20(2): 157-167, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30358845

RESUMO

Aims: Myocardial fibrosis as detected by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is a powerful prognostic marker in hypertrophic cardiomyopathy (HCM) and may be progressive. The precise mechanisms underlying fibrosis progression are unclear. We sought to assess the extent of LGE progression in HCM and explore potential causal mechanisms and clinical implications. Methods and results: Seventy-two HCM patients had two CMR (CMR1-CMR2) at an interval of 5.7 ± 2.8 years with annual clinical follow-up for 6.3 ± 3.6 years from CMR1. A combined endpoint of heart failure progression, cardiac hospitalization, and new onset ventricular tachycardia was assessed. Cine and LGE imaging were performed to assess left ventricular (LV) mass, function, and fibrosis on serial CMR. Stress perfusion imaging and cardiac energetics were undertaken in 38 patients on baseline CMR (CMR1). LGE mass increased from median 4.98 g [interquartile range (IQR) 0.97-13.48 g] to 6.30 g (IQR 1.38-17.51 g) from CMR1 to CMR2. Substantial LGE progression (ΔLGE ≥ 4.75 g) occurred in 26% of patients. LGE increment was significantly higher in those with impaired myocardial perfusion reserve (

Assuntos
Cardiomiopatia Hipertrófica/diagnóstico por imagem , Cardiomiopatia Hipertrófica/patologia , Imagem Cinética por Ressonância Magnética/métodos , Miocárdio/patologia , Meios de Contraste , Progressão da Doença , Feminino , Fibrose/patologia , Gadolínio DTPA , Humanos , Masculino , Meglumina , Pessoa de Meia-Idade , Compostos Organometálicos , Prognóstico , Estudos Retrospectivos , Fatores de Risco
8.
Circ Heart Fail ; 8(6): 1088-93, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26333351

RESUMO

BACKGROUND: Whether the myocardium in nonischemic heart failure experiences oxygen limitation remains a long-standing controversy. We addressed this question in patients with dilated cardiomyopathy (DCM) using a dual approach. First, we tested the changes in myocardial oxygenation between rest and stress states, using oxygenation-sensitive cardiovascular magnetic resonance. Second, we sought to assess the functional consequences of oxygen limitation at rest by measuring myocardial energetics before and after short-term oxygen supplementation. METHODS AND RESULTS: Twenty-six subjects (14 DCM and 12 normal) underwent cardiac magnetic resonance imaging at 3 Tesla to assess cardiac volumes, function, oxygenation, and first-pass perfusion (0.03 mmol/kg Gd-DTPA bolus) at stress and rest (4-6 minutes IV adenosine, 140 µg/kg per minute). Signal intensity change (SIΔ) and myocardial perfusion reserve index (MPRI) were measured from oxygenation and perfusion images, respectively. Furthermore, the effect of oxygen supplementation on resting myocardial energy metabolism was tested using (31)P MR spectroscopy, measuring PCr/ATP ratios in both groups at baseline and after 4 hours of oxygen via facemask in the DCM group. During stress, there were equivalent rises in rate pressure product in both groups (DCM, 76±15% and normal, 79±9%; P=0.84). MPRI was significantly reduced in DCM (1.51±0.11 versus normal 1.86±0.10; P=0.03). However, there was no difference in oxygenation between groups: SIΔ in DCM 17±3% versus normal 20±2% (P=0.38). Furthermore, at a left ventricular segmental level, there was no correlation between oxygenation-sensitive SIΔ and MPRI (R=0.06; P=0.43). Resting PCr/ATP was reduced in DCM (1.66±0.07 versus normal 2.12±0.06; P=0.002). With oxygen supplementation, there was no change in PCr/ATP (1.61±0.08; P=0.58; Δ=0.04±0.05). There was also no effect of oxygen on systolic function (ejection fraction pre oxygen, 34±1%; post oxygen, 36±2%; P=0.46; Δ 2±1%). CONCLUSIONS: Our results demonstrate dissociation between microvascular dysfunction and oxygenation in DCM, suggesting that the impairment of perfusion is not sufficient to cause deoxygenation during stress. Cardiac energetics are unaffected by oxygen supplementation, indicating the absence of relevant myocardial hypoxia at rest. Our study suggests that novel treatments for nonischemic heart failure should focus on efforts to directly target cardiomyocyte function and metabolism rather than oxygen delivery and microvascular function.


Assuntos
Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/fisiopatologia , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/fisiopatologia , Cardiomiopatia Dilatada/terapia , Estudos de Casos e Controles , Circulação Coronária/fisiologia , Teste de Esforço , Feminino , Insuficiência Cardíaca/terapia , Humanos , Imageamento por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio/fisiologia , Oxigenoterapia
10.
J Am Coll Cardiol ; 61(11): 1169-76, 2013 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-23498131

RESUMO

OBJECTIVES: This study sought to assess myocardial perfusion and tissue oxygenation during vasodilator stress in patients with overt hypertrophic cardiomyopathy (HCM), as well as in HCM mutation carriers without left ventricular (LV) hypertrophy, and to compare findings to those in athletes with comparable hypertrophy and normal controls. BACKGROUND: Myocardial perfusion under vasodilator stress is impaired in patients with HCM. Whether this is associated with impaired myocardial oxygenation and tissue ischemia is unknown. Furthermore, it is not known whether perfusion and oxygenation are impaired in HCM mutation carriers without left ventricular hypertrophy (LVH). METHODS: A total of 27 patients with overt HCM, 10 HCM mutation carriers without LVH, 11 athletes, and 20 healthy controls underwent cardiovascular magnetic resonance (CMR) scanning at 3-T. Myocardial function, perfusion (perfusion reserve index [MPRI]), and oxygenation (blood-oxygen level dependent signal intensity [SI] change) under adenosine stress were assessed. RESULTS: MPRI was significantly reduced in HCM (1.3 ± 0.1) compared to controls (1.8 ± 0.1, p < 0.001) and athletes (2.0 ± 0.1, p < 0.001), but remained normal in HCM mutation carriers without LVH (1.7 ± 0.1; p = 0.61 vs. controls, p = 0.02 vs. overt HCM). Oxygenation response was attenuated in overt HCM (SI change 6.9 ± 1.4%) compared to controls (18.9 ± 1.4%, p < 0.0001) and athletes (18.7 ± 2.0%, p < 0.001). Interestingly, HCM mutation carriers without LVH also showed an impaired oxygenation response to adenosine (10.4 ± 2.0%; p = 0.001 vs. controls, p = 0.16 vs. overt HCM, p = 0.003 vs. athletes). CONCLUSIONS: In overt HCM, both perfusion and oxygenation are impaired during vasodilator stress. However, in HCM mutation carriers without LVH, only oxygenation is impaired. In athletes, stress perfusion and oxygenation are normal. CMR assessment of myocardial oxygenation has the potential to become a novel risk factor in HCM.


Assuntos
Cardiomiopatia Hipertrófica/metabolismo , Cardiomiopatia Hipertrófica/fisiopatologia , Circulação Coronária , Miocárdio/metabolismo , Consumo de Oxigênio , Adenosina , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Vasodilatadores
11.
Circ Cardiovasc Imaging ; 6(5): 808-16, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23833283

RESUMO

BACKGROUND: Aortic stenosis (AS) leads to left ventricular (LV) hypertrophy and dysfunction. We hypothesized that cardiac steatosis is involved in the pathophysiology and also assessed whether it is reversible after aortic valve replacement. METHODS AND RESULTS: Thirty-nine patients with severe AS (symptomatic=25, asymptomatic=14) with normal LV ejection fraction and no significant coronary artery disease and 20 age- and sex-matched healthy controls underwent cardiac 1H-magnetic resonance spectroscopy and imaging for the determination of steatosis (myocardial triglyceride content) and cardiac function, including circumferential strain (measured by magnetic resonance tagging). Strain was lower in both symptomatic and asymptomatic AS (-16.4 ± 2.5% and -18.1 ± 2.9%, respectively, versus controls -20.7 ± 2.0%, both P<0.05). Myocardial steatosis was found in both symptomatic and asymptomatic patients with AS (0.89 ± 0.42% in symptomatic AS; 0.75 ± 0.36% in asymptomatic AS versus controls 0.45 ± 0.17, both P<0.05). Importantly, multivariable analysis indicated that steatosis was an independent correlate of impaired LV strain. Spectroscopic measurements of myocardial triglyceride content correlated significantly with histological analysis of biopsies obtained during aortic valve replacement. At 8.0 ± 2.1 months after aortic valve replacement, steatosis and strain had recovered toward normal. CONCLUSIONS: Pronounced myocardial steatosis is present in severe AS, regardless of symptoms, and is independently associated with the degree of LV strain impairment. Myocardial triglyceride content measured by magnetic resonance spectroscopy correlates with histological quantification. Steatosis and strain impairment are reversible after aortic valve replacement. Our findings suggest a novel pathophysiological mechanism in AS, myocardial steatosis, which may be amenable to treatment, thus potentially delaying onset of LV dysfunction.


Assuntos
Estenose da Valva Aórtica/complicações , Contração Miocárdica , Miocárdio/metabolismo , Triglicerídeos/metabolismo , Disfunção Ventricular Esquerda/etiologia , Função Ventricular Esquerda , Idoso , Estenose da Valva Aórtica/diagnóstico , Estenose da Valva Aórtica/cirurgia , Biópsia , Estudos de Casos e Controles , Distribuição de Qui-Quadrado , Ecocardiografia , Feminino , Implante de Prótese de Valva Cardíaca , Humanos , Modelos Lineares , Imagem Cinética por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Miocárdio/patologia , Valor Preditivo dos Testes , Fatores de Risco , Índice de Gravidade de Doença , Resultado do Tratamento , Disfunção Ventricular Esquerda/diagnóstico , Disfunção Ventricular Esquerda/fisiopatologia
12.
Circ Cardiovasc Imaging ; 5(6): 726-33, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23071146

RESUMO

BACKGROUND: Noncontrast magnetic resonance T1 mapping reflects a composite of both intra- and extracellular signal. We hypothesized that noncontrast T1 mapping can characterize the myocardium beyond that achieved by the well-established late gadolinium enhancement (LGE) technique (which detects focal fibrosis) in both hypertrophic (HCM) and dilated (DCM) cardiomyopathy, by detecting both diffuse and focal fibrosis. METHODS AND RESULTS: Subjects underwent Cardiovascular Magnetic Resonance imaging at 3T (28 HCM, 18 DCM, and 12 normals). Matching short-axis slices were acquired for cine, T1 mapping, and LGE imaging (0.1 mmol/kg). Circumferential strain was measured in the midventricular slice, and (31)P magnetic resonance spectroscopy was acquired for the septum of the midventricular slice. Mean T1 relaxation time was increased in HCM and DCM (HCM 1209±28 ms, DCM 1225±42 ms, normal 1178±13 ms, P<0.05). There was a weak correlation between mean T1 and LGE (r=0.32, P<0.001). T1 values were higher in segments with LGE than in those without (HCM with LGE 1228±41 ms versus no LGE 1192±79 ms, P<0.01; DCM with LGE 1254±73 ms versus no LGE 1217±52 ms, P<0.01). However, in both HCM and DCM, even in segments unaffected by LGE, T1 values were significantly higher than normal (P<0.01). T1 values correlated with disease severity, being increased as wall thickness increased in HCM; conversely, in DCM, T1 values were highest in the thinnest myocardial segments. T1 values also correlated significantly with circumferential strain (r=0.42, P<0.01). Interestingly, this correlation remained statistically significant even for the slices without LGE (r=0.56, P=0.04). Finally, there was also a statistically significant negative correlation between T1 values and phosphocreatine/adenosine triphosphate ratios (r=-0.59, P<0.0001). CONCLUSIONS: In HCM and DCM, noncontrast T1 mapping detects underlying disease processes beyond those assessed by LGE in relatively low-risk individuals.


Assuntos
Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Hipertrófica/diagnóstico , Gadolínio DTPA , Imagem Cinética por Ressonância Magnética/métodos , Miocárdio/patologia , Meios de Contraste , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença
13.
Heart ; 98(14): 1083-90, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22739638

RESUMO

OBJECTIVE: To determine the effects of short-term exercise training on cardiac function and metabolism during rest and physical exercise in patients with heart failure from dilated cardiomyopathy (DCM). DESIGN: Patients with DCM (n=15, age 58±2 years, NYHA class I-III) were studied before and after 8 weeks of cycle exercise for 20 min, five times per week. MAIN OUTCOME MEASURES: Cardiac volumes, function and high energy phosphate metabolism were measured using cardiac magnetic resonance during rest and 7 min of acute physical exercise (leg-raising). RESULTS: At baseline, average left ventricular ejection fraction (LVEF) was 38±3%, which did not alter during 7 min of exercise. After 8 weeks of home exercise training, there was a 16% improvement in resting LVEF to 44±3% (p<0.01). Training caused a further 20% improvement in LVEF (p<0.05) during acute physical exercise. There was a negative correlation between subjects' baseline level of exercise and change in LVEF (r=-0.67, p<0.05), with sedentary patients having the greatest improvement. Cardiac phosphocreatine (PCr) to ATP ratio did not change during acute physical exercise or after exercise training. CONCLUSIONS: Short-term exercise training improves resting LVEF and LVEF with acute physical exercise with sedentary patients having the greatest improvement. There were no changes in cardiac PCr to ATP, before or after exercise training, suggesting that the improved cardiac function was not caused by improved energetics. Therefore, peripheral factors likely underlie the improved cardiac function in patients with heart failure after short-term exercise.


Assuntos
Cardiomiopatia Dilatada/terapia , Metabolismo Energético , Terapia por Exercício/métodos , Exercício Físico/fisiologia , Fosfatos/metabolismo , Descanso/fisiologia , Função Ventricular , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/fisiopatologia , Feminino , Seguimentos , Humanos , Imagem Cinética por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Volume Sistólico , Fatores de Tempo , Resultado do Tratamento
14.
Prog Cardiovasc Dis ; 54(3): 320-7, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22014498

RESUMO

Cardiac magnetic resonance spectroscopy (MRS) is a noninvasive tool for the assessment of myocardial metabolism, without the use of radiation or intravenous contrast agents. Using the intrinsic magnetic resonance signals from nuclei, including (31)Phosphorus, (1)Hydrogen, (23)Sodium, and (13)Carbon and, more recently, hyperpolarization techniques, MRS provides a comprehensive metabolic assessment of cardiac muscle. This highly versatile technique has provided insights into the pathophysiology of cardiac metabolism in a wide range of conditions, including ischemic heart disease, heart failure, genetic cardiomyopathies, heart transplantation, hypertensive heart disease, valvular heart disease, and diabetes. In addition, MRS has value in the assessment of prognosis and for monitoring therapeutic strategies in heart failure. However, because of the low temporal and spatial resolution of the technique, MRS has so far been limited to research applications. With higher field strength magnets and novel hyperpolarization techniques, the promise of using MRS for clinical applications may eventually be fulfilled.


Assuntos
Metabolismo Energético , Cardiopatias/diagnóstico , Espectroscopia de Ressonância Magnética , Miocárdio/metabolismo , Cardiopatias/metabolismo , Cardiopatias/fisiopatologia , Cardiopatias/terapia , Humanos , Valor Preditivo dos Testes , Prognóstico , Índice de Gravidade de Doença
16.
J Am Soc Echocardiogr ; 20(5): 537.e3-5, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17484996

RESUMO

Transesophageal echocardiography was requested for a 20-year-old woman admitted to the intensive care department after being involved, as a restrained driver, in a road traffic accident. During the study a striking abnormality was noted around the left atrial appendage and left upper pulmonary vein. The clinical history of blunt chest trauma, and echocardiographic appearances suggestive of a flap, indicated the diagnosis was left atrial appendage and left upper pulmonary vein dissection. The report summarizes the literature on traumatic injury to the left upper pulmonary vein and left atrial appendage and demonstrates the importance of comprehensive echocardiographic studies to identify unexpected pathology.


Assuntos
Apêndice Atrial/lesões , Ecocardiografia Transesofagiana/métodos , Traumatismos Cardíacos/diagnóstico por imagem , Veias Pulmonares/lesões , Ferimentos não Penetrantes/diagnóstico por imagem , Acidentes de Trânsito , Adulto , Apêndice Atrial/diagnóstico por imagem , Diagnóstico Diferencial , Feminino , Seguimentos , Humanos , Veias Pulmonares/diagnóstico por imagem , Ruptura , Índices de Gravidade do Trauma
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