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1.
Am J Cardiol ; 125(5): 678-684, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31948661

RESUMO

Insulin resistance early after acute myocardial infarction is associated with increased heart failure and mortality. OMEGA-REMODEL was a prospective double-blind 1:1 randomized control trial of patients with AMI. We reported that 6-month treatment with omega-3 fatty acid (O-3FA) 4 g/day attenuated cardiac remodeling accompanied by reduction in inflammation. We hypothesized that insulin resistance modifies the therapeutic effect of O-3FA on post-MI cardiac remodeling. The OMEGA-REMODEL study group was dichotomized according to cohort- and gender-specific median cutoff value of leptin-to-adiponectin ratio (LAR) at baseline (LAR-Hi vs LAR-Lo). Mixed model regression analyses were used to evaluate effect modification of O-3FA on reduction of left ventricular end-systolic volume index (LVESVI) by LAR status. Baseline LAR was evaluated on 325 patients (59 ± 11 years, 81% male). A total of 168 patients were categorized in LAR-Lo, and 157 in LAR-Hi. O-3FA treatment resulted in significant LVESVI reduction in patients with LAR-Lo but not with LAR-Hi (p = 0.0002 vs 0.66, respectively). Mixed model regression analysis showed significant modification of LAR on O-3FA's treatment effect in attenuating LVESVI (p = 0.021). In conclusion, this post-hoc efficacy analysis suggests that LAR status significantly modified O-3FA's treatment effect in attenuating cardiac remodeling. During the convalescent phase of acute infarct healing, patients with lower insulin resistance estimated by LAR appear to derive more therapeutic response from O-3FA toward improvement of LVESVI.

2.
Circulation ; 141(1): 21-33, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31779467

RESUMO

BACKGROUND: Cardiac dysfunction and cardiovascular events are prevalent among patients with chronic kidney disease without overt obstructive coronary artery disease, but the mechanisms remain poorly understood. Coronary microvascular dysfunction has been proposed as a link between abnormal renal function and impairment of cardiac function and cardiovascular events. We aimed to investigate the relations between chronic kidney disease, coronary microvascular dysfunction, cardiac dysfunction, and adverse cardiovascular outcomes. METHODS: Patients undergoing cardiac stress positron emission tomography, echocardiogram, and renal function ascertainment at Brigham and Women's Hospital were studied longitudinally. Patients free of overt coronary (summed stress score <3 and without a history of ischemic heart disease), valvular, and end-organ disease were followed up for the adverse composite outcome of death or hospitalization for myocardial infarction or heart failure. Coronary flow reserve (CFR) was determined from positron emission tomography. Echocardiograms were used to measure cardiac mechanics: diastolic (lateral and septal E/e') and systolic (global longitudinal, radial, and circumferential strain). Image analyses and event adjudication were blinded. The associations between estimated glomerular filtration rate (eGFR), CFR, diastolic and systolic indices, and adverse cardiovascular outcomes were assessed in adjusted models and mediation analyses. RESULTS: Of the 352 patients (median age, 65 years; 63% female; 22% black) studied, 35% had an eGFR <60 mL·min-1·1.73 m-2, a median left ventricular ejection fraction of 62%, and a median CFR of 1.8. eGFR and CFR were associated with diastolic and systolic indices, as well as future cardiovascular events (all P<0.05). In multivariable models, CFR, but not eGFR, was independently associated with cardiac mechanics and cardiovascular events. The associations between eGFR, cardiac mechanics, and cardiovascular events were partly mediated via CFR. CONCLUSIONS: Coronary microvascular dysfunction, but not eGFR, was independently associated with abnormal cardiac mechanics and an increased risk of cardiovascular events. Coronary microvascular dysfunction may mediate the effect of chronic kidney disease on abnormal cardiac function and cardiovascular events in those without overt coronary artery disease.

3.
J Am Coll Cardiol ; 74(14): 1741-1755, 2019 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-31582133

RESUMO

BACKGROUND: Stress cardiac magnetic resonance imaging (CMR) has demonstrated excellent diagnostic and prognostic value in single-center studies. OBJECTIVES: This study sought to investigate the prognostic value of stress CMR and downstream costs from subsequent cardiac testing in a retrospective multicenter study in the United States. METHODS: In this retrospective study, consecutive patients from 13 centers across 11 states who presented with a chest pain syndrome and were referred for stress CMR were followed for a target period of 4 years. The authors associated CMR findings with a primary outcome of cardiovascular death or nonfatal myocardial infarction using competing risk-adjusted regression models and downstream costs of ischemia testing using published Medicare national payment rates. RESULTS: In this study, 2,349 patients (63 ± 11 years of age, 47% female) were followed for a median of 5.4 years. Patients with no ischemia or late gadolinium enhancement (LGE) by CMR, observed in 1,583 patients (67%), experienced low annualized rates of primary outcome (<1%) and coronary revascularization (1% to 3%), across all years of study follow-up. In contrast, patients with ischemia+/LGE+ experienced a >4-fold higher annual primary outcome rate and a >10-fold higher rate of coronary revascularization during the first year after CMR. Patients with ischemia and LGE both negative had low average annual cost spent on ischemia testing across all years of follow-up, and this pattern was similar across the 4 practice environments of the participating centers. CONCLUSIONS: In a multicenter U.S. cohort with stable chest pain syndromes, stress CMR performed at experienced centers offers effective cardiac prognostication. Patients without CMR ischemia or LGE experienced a low incidence of cardiac events, little need for coronary revascularization, and low spending on subsequent ischemia testing. (Stress CMR Perfusion Imaging in the United States [SPINS]: A Society for Cardiovascular Resonance Registry Study; NCT03192891).

4.
PLoS One ; 14(9): e0222061, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31532795

RESUMO

BACKGROUND: The double-blind OMEGA-REMODEL placebo-controlled randomized trial of high-dose omega-3 fatty acids (O-3FA) post-acute myocardial infarction (AMI) reported improved cardiac remodeling and attenuation of non-infarct myocardial fibrosis. Fatty acid desaturase 2 (FADS2) gene cluster encodes key enzymes in the conversion of essential omega-3 and omega-6 fatty acids into active arachidonic (ArA) and eicosapentaenoic acids (EPA), which influence cardiovascular outcomes. METHODS AND RESULTS: We tested the hypothesis that the genotypic status of FADS2 (rs1535) modifies therapeutic response of O-3FA in post-AMI cardiac remodeling in 312 patients. Consistent with known genetic polymorphism of FADS2, patients in our cohort with the guanine-guanine (GG) genotype had the lowest FADS2 activity assessed by arachidonic acid/linoleic acid (ArA/LA) ratio, compared with patients with the adenine-adenine (AA) and adenine-guanine (AG) genotypes (GG:1.62±0.35 vs. AA: 2.01±0.36, p<0.0001; vs. AG: 1.76±0.35, p = 0.03). When randomized to 6-months of O-3FA treatment, GG patients demonstrated significant lowering of LV end-systolic volume index (LVESVi), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and galectin-3 levels compared to placebo (-4.4 vs. 1.2 ml/m2, -733 vs. -181 pg/mL, and -2.0 vs. 0.5 ng/mL; p = 0.006, 0.006, and 0.03, respectively). In contrast, patients with either AA or AG genotype did not demonstrate significant lowering of LVESVi, NT-proBNP, or galectin-3 levels from O-3FA treatment, compared to placebo. The odds ratios for improving LVESVi by 10% with O-3FA treatment was 7.2, 1.6, and 1.2 in patients with GG, AG, and AA genotypes, respectively. CONCLUSION: Genetic profiling using FADS2 genotype can predict the therapeutic benefits of O-3FA treatment against adverse cardiac remodeling during the convalescent phase of AMI. CLINICAL TRIAL REGISTRATION INFORMATION: clinicaltrials.gov Identifier: NCT00729430.

5.
JACC Cardiovasc Imaging ; 12(7 Pt 1): 1165-1173, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30121266

RESUMO

OBJECTIVES: This study sought to test whether relative apical sparing (RELAPS) of left ventricular (LV) longitudinal strain (LS) in cardiac amyloidosis (CA) is explained by regional differences in markers of amyloid burden (18F-florbetapir uptake by positron emission tomography [PET] and/or extracellular volume fraction [ECV] by cardiac magnetic resonance (CMR)]. BACKGROUND: Further knowledge of the pathophysiological basis for RELAPS can help understand the adverse outcomes associated with apical LS impairment. METHODS: This was a prospective study of 32 subjects (age 62 ± 7 years; 50% males) with light chain CA. All subjects underwent two-dimensional echocardiography for LS estimation and 18F-florbetapir PET for quantification of LV florbetapir retention index (RI). A subset also underwent CMR (n = 22) for ECV quantification. Extracellular LV mass (LV mass*ECV) and total florbetapir binding (extracellular LV mass*florbetapir RI) were also calculated. All parameters were measured globally and regionally (base, mid, and apex). RESULTS: There was a significant base-to-apex gradient in LS (-7.4 ± 3.2% vs. -8.6 ± 4.0% vs. -20.8 ± 6.6%; p < 0.0001), maximal LV wall thickness (15.7 ± 1.9 cm vs. 15.4 ± 2.9 cm vs. 10.1 ± 2.4 cm; p < 0.0001), and LV mass (74.8 ± 21.2 g vs. 60.8 ± 17.3 g vs. 23.4 ± 6.2 g; p < 0.0001). In contrast, florbetapir RI (0.089 ± 0.03 µmol/min/g vs. 0.097 ± 0.03 µmol/min/g vs. 0.085 ± 0.03 µmol/min/g; p = 0.45) and ECV (0.53 ± 0.08 vs. 0.49 ± 0.08 vs. 0.49 ± 0.07; p = 0.15) showed no significant base-to-apex gradient in the tissue concentration or proportion of amyloid infiltration, whereas markers of total amyloid load, such as total florbetapir binding (3.4 ± 1.7 µmol/min vs. 2.8 ± 1.5 µmol/min vs. 0.93 ± 0.49 µmol/min; p < 0.0001) and extracellular LV mass (40.0 ± 15.6 g vs. 30.2 ± 10.9 g vs. 11.6 ± 3.9 g; p < 0.0001), did show a marked base-to-apex gradient. CONCLUSIONS: Segmental differences in the distribution of the total amyloid mass, rather than the proportion of amyloid deposits, appear to explain the marked regional differences in LS in CA. Although these 2 matrices are clearly related concepts, they should not be used interchangeably.

6.
Int J Cardiol ; 272: 323-328, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30082119

RESUMO

BACKGROUND: Patients with chronic kidney disease are at increased risk of cardiovascular disease (CVD). Even after kidney transplant, the rate of CVD events and death remain elevated. Early detection of patients at risk would be helpful for guiding aggressive preventive therapy. The purpose of this study was to evaluate global longitudinal strain (GLS) as a predictor of CVD events and death after kidney transplant. METHOD: Among patients with successful kidney transplant between 3/2009 and 12/2012 at our institution, 111 individuals had an echocardiogram within 6 months of the transplant. Medical records were evaluated for demographics and patient characteristics. Echocardiograms were analyzed for conventional measurements, and GLS was assessed using speckle-tracking analysis. RESULTS: The median age of the study sample was 54 years. Overall, 60% were men; 35% were non-Hispanic black, and 50% Hispanic. After a mean follow-up of 3.8 ±â€¯0.5 years, there were 21 cardiovascular events or deaths. Patients who experienced an event were older, more frequently had a history of coronary artery disease, and had higher LV filling/longitudinal diastolic annular velocity (E/e') than those who did not. GLS was significantly associated with event-free survival even after adjusting for age, sex, race-ethnicity, hypertension, diabetes, history of coronary artery disease or heart failure, and E/e'. CONCLUSION: Reduced GLS peri-transplant is significantly associated with increased CVD events or death after kidney transplant. Larger studies are required to determine the incremental predictive value of GLS over clinical and other echocardiographic parameters for adverse CVD events following renal transplantation.


Assuntos
Doenças Cardiovasculares/diagnóstico por imagem , Doenças Cardiovasculares/mortalidade , Transplante de Rim/efeitos adversos , Transplante de Rim/mortalidade , Complicações Pós-Operatórias/diagnóstico por imagem , Complicações Pós-Operatórias/mortalidade , Adulto , Doenças Cardiovasculares/etiologia , Estudos de Coortes , Morte , Feminino , Humanos , Transplante de Rim/tendências , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/etiologia , Estudos Retrospectivos , Fatores de Risco
7.
J Mol Cell Cardiol ; 117: 36-48, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29481819

RESUMO

Tissue transglutaminase (tTG) is a multifunctional protein with a wide range of enzymatic and non-enzymatic functions. We have recently demonstrated that tTG expression is upregulated in the pressure-overloaded myocardium and exerts fibrogenic actions promoting diastolic dysfunction, while preventing chamber dilation. Our current investigation dissects the in vivo and in vitro roles of the enzymatic effects of tTG on fibrotic remodeling in pressure-overloaded myocardium. Using a mouse model of transverse aortic constriction, we demonstrated perivascular and interstitial tTG activation in the remodeling pressure-overloaded heart. tTG inhibition through administration of the selective small molecule tTG inhibitor ERW1041E attenuated left ventricular diastolic dysfunction and reduced cardiomyocyte hypertrophy and interstitial fibrosis in the pressure-overloaded heart, without affecting chamber dimensions and ejection fraction. In vivo, tTG inhibition markedly reduced myocardial collagen mRNA and protein levels and attenuated transcription of fibrosis-associated genes. In contrast, addition of exogenous recombinant tTG to fibroblast-populated collagen pads had no significant effects on collagen transcription, and instead increased synthesis of matrix metalloproteinase (MMP)3 and tissue inhibitor of metalloproteinases (TIMP)1 through transamidase-independent actions. However, enzymatic effects of matrix-bound tTG increased the thickness of pericellular collagen in fibroblast-populated pads. tTG exerts distinct enzymatic and non-enzymatic functions in the remodeling pressure-overloaded heart. The enzymatic effects of tTG are fibrogenic and promote diastolic dysfunction, but do not directly modulate the pro-fibrotic transcriptional program of fibroblasts. Targeting transamidase-dependent actions of tTG may be a promising therapeutic strategy in patients with heart failure and fibrosis-associated diastolic dysfunction.


Assuntos
Cardiomegalia/enzimologia , Cardiomegalia/patologia , Proteínas de Ligação ao GTP/antagonistas & inibidores , Miocárdio/patologia , Miócitos Cardíacos/enzimologia , Miócitos Cardíacos/patologia , Pressão , Transglutaminases/antagonistas & inibidores , Animais , Cardiomegalia/genética , Cardiomegalia/fisiopatologia , Colágeno/metabolismo , Diástole/efeitos dos fármacos , Matriz Extracelular/metabolismo , Feminino , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/patologia , Fibrose , Proteínas de Ligação ao GTP/metabolismo , Hipertrofia Ventricular Esquerda/patologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Isoxazóis/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Miócitos Cardíacos/efeitos dos fármacos , Pirrolidinas/farmacologia , Quinolinas/farmacologia , Proteínas Recombinantes/farmacologia , Volume Sistólico/efeitos dos fármacos , Inibidores Teciduais de Metaloproteinases/genética , Inibidores Teciduais de Metaloproteinases/metabolismo , Transcrição Genética/efeitos dos fármacos , Transglutaminases/metabolismo , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genética , Remodelação Ventricular/efeitos dos fármacos
9.
Echocardiography ; 34(9): 1374-1375, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28752531

RESUMO

A 66-year-old woman presented with frequent premature ventricular contractions (PVC) and akinesis of the basal septum on echocardiography. Coronary angiography was normal. Cardiac magnetic resonance showed mid-wall enhancement. Positron emission tomography showed a perfusion defect at the same location using 13N-ammonia, but increased 18-fluorodeoxyglucose uptake. These findings supported the diagnosis of cardiac sarcoidosis. High-dose steroids initially reduced frequency of PVCs but had to be withdrawn due to severe side effects. An ICD was implanted. Our case demonstrates the utility of multimodality imaging to diagnose and guide management of this entity.


Assuntos
Cardiomiopatias/diagnóstico , Ecocardiografia/métodos , Imagem Cinética por Ressonância Magnética/métodos , Imagem Multimodal , Tomografia por Emissão de Pósitrons/métodos , Sarcoidose/diagnóstico , Idoso , Diagnóstico Diferencial , Feminino , Humanos
10.
Am J Cardiovasc Dis ; 5(2): 119-26, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26309775

RESUMO

BACKGROUND: During a healthy pregnancy women experience cardiovascular and hemodynamic changes and normal ranges of left ventricular (LV) function on two-dimensional speckle tracking echocardiography (STE) are not well defined. The aim of this study was to describe the cardiovascular changes that occur during the second and third trimesters of a healthy pregnancy using STE. METHODS: Pregnant subjects were enrolled retrospectively if they underwent a transthoracic echocardiography (TTE) between 2011-2014. Subjects with abnormal TTE findings, hypertension, diabetes, preeclampsia, prior cardiac surgery, poor imaging quality or in the 1st trimester were excluded. A total of 74 pregnant subjects were categorized into the 2nd or 3rd trimesters. Twenty-one healthy age-matched females were selected as a control group. RESULTS: The heart undergoes extensive remodeling during pregnancy with increased LV septal thickness, posterior wall thickness, cavity size and mass (p=0.045, p=0.002, p<0.001, p=0.018, respectively). However, myocardial mechanical function measured by: global longitudinal strain, radial strain, circumferential strain, systolic and diastolic global longitudinal strain rate (GLSR), global radial strain rate (GRSR) and global circumferential strain rate, remains preserved. Only time to peak strain rate corrected for heart rate for diastolic GRSR and diastolic GLSR were significantly increased in the third trimester (p=0.016 for both). CONCLUSION: Despite extensive heart remodeling, many STE derived parameters of LV function in healthy pregnant women remain unchanged and valid for women in the 2nd and 3rd trimester. Future studies investigating early detection of pregnancy related heart disease can refer to these parameters as reference ranges.

11.
Expert Rev Cardiovasc Ther ; 13(7): 853-66, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26058981

RESUMO

Strain and strain rate imaging (also known as deformation imaging) are techniques used to measure myocardial deformation. These newer echocardiographic modalities overcome the limitations of conventional echocardiography and provide a sensitive means of objectively quantifying regional and global myocardial function. It has enabled us to better understand regional myocardial function and risk stratify patients with coronary artery disease, cardiomyopathies and valvular heart disease. Also, they have been used to assess left ventricular dyssynchrony, predict responders and optimize cardiac resynchronization therapy. However, the lack of standardization and inter-vendor variability in measurements are major roadblocks to using deformation imaging in routine clinical practice. This article discusses the fundamental concept of deformation, in particular relating to strain and strain rate imaging using speckle tracking imaging and tissue Doppler imaging, the clinical applications and its prognostic implications.


Assuntos
Ecocardiografia Doppler/métodos , Cardiopatias/diagnóstico por imagem , Cardiopatias/etiologia , Cardiopatias/terapia , Humanos , Modelos Biológicos , Prognóstico , Sobrevivência de Tecidos
14.
Echocardiography ; 30(8): 880-8, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23488864

RESUMO

BACKGROUND: Echocardiography (echo)-quantified LV stroke volume (SV) is widely used to assess systolic performance after acute myocardial infarction (AMI). This study compared 2 common echo approaches - predicated on flow (Doppler) and linear chamber dimensions (Teichholz) - to volumetric SV and global infarct parameters quantified by cardiac magnetic resonance (CMR). METHODS: Multimodality imaging was performed as part of a post-AMI registry. For echo, SV was measured by Doppler and Teichholz methods. Cine-CMR was used for volumetric SV and LVEF quantification, and delayed-enhancement (DE) CMR for infarct size. RESULTS: Overall, 142 patients underwent same day echo and CMR. On echo, mean SV by Teichholz (78 ± 17 mL) was slightly higher than Doppler (75 ± 16 mL; Δ = 3 ± 13 mL; P = 0.02). Compared to SV on CMR (78 ± 18 mL), mean difference by Teichholz (Δ = -0.2 ± 14; P = 0.89) was slightly smaller than Doppler (Δ = -3 ± 14; P = 0.02), but limits of agreement were similar between CMR and echo methods (Teichholz: -28, 27 mL, Doppler: -31, 24 mL). For Teichholz, differences with CMR SV were greatest among patients with anteroseptal or lateral wall hypokinesis (P < 0.05). For Doppler, differences were associated with aortic valve abnormalities or root dilation (P = 0.01). SV by both echo methods decreased stepwise in relation to global LV injury as assessed by CMR-quantified LVEF and infarct size (P < 0.01). CONCLUSIONS: Teichholz and Doppler calculated SV yield similar magnitude of agreement with CMR. Teichholz differences with CMR increase with septal or lateral wall contractile dysfunction, whereas Doppler yields increased offsets in patients with aortic remodeling.


Assuntos
Ecocardiografia/estatística & dados numéricos , Interpretação de Imagem Assistida por Computador/métodos , Angiografia por Ressonância Magnética/estatística & dados numéricos , Imagem Cinética por Ressonância Magnética/estatística & dados numéricos , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/epidemiologia , Volume Sistólico , Algoritmos , Meios de Contraste , Ecocardiografia/métodos , Feminino , Humanos , Aumento da Imagem/métodos , Angiografia por Ressonância Magnética/métodos , Imagem Cinética por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , New York/epidemiologia , Prevalência , Reprodutibilidade dos Testes , Fatores de Risco , Sensibilidade e Especificidade
15.
Proc Natl Acad Sci U S A ; 108(21): 8565-70, 2011 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-21571641

RESUMO

Cardiac conduction abnormalities remain a major cause of death and disability worldwide. However, as of today, there is no standard clinical imaging modality that can noninvasively provide maps of the electrical activation. In this paper, electromechanical wave imaging (EWI), a novel ultrasound-based imaging method, is shown to be capable of mapping the electromechanics of all four cardiac chambers at high temporal and spatial resolutions and a precision previously unobtainable in a full cardiac view in both animals and humans. The transient deformations resulting from the electrical activation of the myocardium were mapped in 2D and combined in 3D biplane ventricular views. EWI maps were acquired during five distinct conduction configurations and were found to be closely correlated to the electrical activation sequences. EWI in humans was shown to be feasible and capable of depicting the normal electromechanical activation sequence of both atria and ventricles. This validation of EWI as a direct, noninvasive, and highly translational approach underlines its potential to serve as a unique imaging tool for the early detection, diagnosis, and treatment monitoring of arrhythmias through ultrasound-based mapping of the transmural electromechanical activation sequence reliably at the point of care, and in real time.


Assuntos
Diagnóstico por Imagem/métodos , Técnicas Eletrofisiológicas Cardíacas/métodos , Sistema de Condução Cardíaco/diagnóstico por imagem , Modelos Cardiovasculares , Sistema de Condução Cardíaco/fisiologia , Ventrículos do Coração/diagnóstico por imagem , Humanos , Ultrassonografia , Função Ventricular
16.
Phys Med Biol ; 56(4): 1155-72, 2011 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-21285479

RESUMO

The capability of currently available echocardiography-based strain estimation techniques to fully map myocardial abnormality at early stages of myocardial ischemia is yet to be investigated. In this study, myocardial elastography (ME), a radio-frequency (RF)-based strain imaging technique that maps the full 2D transmural angle-independent strain tensor in standard echocardiographic views at both high spatial and temporal resolution is presented. The objectives were to (1) evaluate the performance of ME on mapping the onset, extent and progression of myocardial ischemia at graded coronary constriction levels (from partial to complete coronary flow reduction), and (2) validate the accuracy of the strain estimates against sonomicrometry (SM) measurements. A non-survival canine ischemic model (n = 5) was performed by gradually constricting the left anterior descending (LAD) coronary blood flow from 0% (baseline blood flow) to 100% (zero blood flow) at 20% increments. An open-architecture ultrasound system was used to acquire RF echocardiograms in a standard full short-axis view at the frame rate of 211 fps, at least twice higher than what is typically used in conventional echocardiographic systems, using a previously developed, fully automated composite technique. Myocardial deformation was estimated by ME and validated against sonomicrometry. ME estimates and maps transmural (1) 2D displacements using RF cross-correlation and recorrelation; and (2) 2D polar (radial and circumferential) strains, derived from 2D (i.e. both lateral and axial) displacement components, at high accuracy. Full-view strain images were shown and found to reliably depict decreased myocardial function in the region at risk at increased levels of coronary flow reduction. The ME radial strain was deemed to be a more sensitive, quantitative, regional measure of myocardial ischemia as a result of coronary flow reduction when compared to the conventional wall motion score index and ejection fraction. Good agreement (0.22% strain bias, 95% limits of agreement) using Bland-Altman analysis and good correlation (r = 0.84) were found between the ME and SM measurements. These findings demonstrate for the first time that ME could map angle-independent strains to non-invasively detect, localize and characterize the early onset of myocardial ischemia, i.e. at 40%, and possibly as low as 20%, LAD flow reduction, which could be further associated with the severity of coronary stenosis.


Assuntos
Ecocardiografia/métodos , Técnicas de Imagem por Elasticidade/métodos , Isquemia Miocárdica/diagnóstico por imagem , Isquemia Miocárdica/fisiopatologia , Animais , Circulação Coronária , Cães , Coração/fisiopatologia , Processamento de Imagem Assistida por Computador , Masculino , Movimento , Reprodutibilidade dos Testes , Estresse Fisiológico , Volume Sistólico
17.
Ultrasonics ; 50(2): 208-15, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19863987

RESUMO

Electromechanical wave imaging is a novel technique for the noninvasive mapping of conduction waves in the left ventricle through the combination of ECG gating, high frame rate ultrasound imaging and radio-frequency (RF)-based displacement estimation techniques. In this paper, we describe this new technique and characterize the origin and velocity of the wave under distinct pacing schemes. First, in vivo imaging (30 MHz) was performed on anesthetized, wild-type mice (n=12) at high frame rates in order to take advantage of the transient electromechanical coupling occurring in the myocardium. The RF signal acquisition in a long-axis echocardiographic view was gated between consecutive R-wave peaks of the mouse electrocardiogram (ECG) and yielded an ultra-high RF frame rate of 8000 frames/s (fps). The ultrasound RF signals in each frame were digitized at 160 MHz. Axial, frame-to-frame displacements were estimated using 1D cross-correlation (window size of 240 microm, overlap of 90%). Three pacing protocols were sequentially applied in each mouse: (1) sinus rhythm (SR), (2) right-atrial (RA) pacing and (3) right-ventricular (RV) pacing. Pacing was performed using an eight-electrode catheter placed into the right side of the heart with the capability of pacing from any adjacent bipole. During a cardiac cycle, several waves were depicted on the electromechanical wave images that propagated transmurally and/or from base to apex, or apex to base, depending on the type of pacing and the cardiac phase. Through comparison between the ciné-loops and their corresponding ECG obtained at different pacing protocols, we were able to identify and separate the electrically induced, or contraction, waves from the hemodynamic (or, blood-wall coupling) waves. In all cases, the contraction wave was best observed along the posterior wall starting at the S-wave of the ECG, which occurs after Purkinje fiber, and during myocardial, activation. The contraction wave was identified based on the fact that it changed direction only when the pacing origin changed, i.e., it propagated from the apex to the base at SR and RA pacing and from base to apex at RV pacing. This reversal in the wave propagation direction was found to be consistent in all mice scanned and the wave velocity values fell within the previously reported conduction wave range with statistically significant differences between SR/RA pacing (0.85+/-0.22 m/s and 0.84+/-0.20 m/s, respectively) and RV pacing (-0.52+/-0.31 m/s; p<0.0001). This study thus shows that imaging the electromechanical function of the heart noninvasively is feasible. It may therefore constitute a unique noninvasive method for conduction wave mapping of the entire left ventricle. Such a technology can be extended to 3D mapping and/or used for early detection of dyssynchrony, arrhythmias, left-bundle branch block, or other conduction abnormalities as well as diagnosis and treatment thereof.


Assuntos
Ecocardiografia/métodos , Técnicas de Imagem por Elasticidade/métodos , Ventrículos do Coração/diagnóstico por imagem , Animais , Estimulação Cardíaca Artificial , Eletrocardiografia , Estudos de Viabilidade , Processamento de Imagem Assistida por Computador , Camundongos , Ondas de Rádio , Estresse Mecânico , Função Ventricular
18.
IEEE Trans Med Imaging ; 29(3): 625-35, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19709966

RESUMO

Electromechanical wave imaging (EWI) has recently been introduced as a noninvasive, ultrasound-based imaging modality, which could map the electrical activation of the heart in various echocardiographic planes in mice, dogs, and humans in vivo. By acquiring radio-frequency (RF) frames at very high frame rates (390-520 Hz), the onset of small, localized, transient deformations resulting from the electrical activation of the heart, i.e., generating the electromechanical wave (EMW), can be mapped. The correlation between the EMW and the electrical activation speed and pacing scheme has previously been reported. In this study, we pursue the development of EWI using both displacements and strains and analysis of the EMW properties in dogs in vivo for early detection of ischemia. EWI was performed in normal and ischemic open-chest dogs during sinus rhythm. Ischemia of increasing severity was obtained by gradually obstructing the left-anterior descending (LAD) coronary artery flow. We also introduce the novel method of motion-matching that achieves the reconstruction of the full EWI ciné-loop at very high frame rates even when the ECG may be irregular or unavailable. Incremental displacements were previously used by our group to map the EMW. This paper focuses on the associated incremental strains, which facilitate the interpretation of the EMW by relating it directly to contraction. Moreover, we define the onset of the EMW as the time, at which the incremental strains change sign after the onset of the QRS complex of the ECG. Based on this definition, isochronal representations of the EMW were generated using a semi-automated method. The isochronal representation of the EMW during sinus rhythm was reproducible and shown similar to electrical activation maps previously reported in the literature. After segmentation using a contour-tracking method, the two- and four-chamber views were imaged and displayed in bi-plane views, allowing a 3-D interpretation of the EMW. EWI was shown to be sensitive to the presence of intermediate ischemia. EWI localized the ischemic region when the LAD flow was obstructed at 60% and beyond and was capable of mapping the increase of the ischemic region size as the LAD occlusion level increased. In conclusion, the activation maps and wave patterns obtained with EWI were similar to the electrical equivalents previously reported in the literature. Moreover, EWI was found to be sensitive enough to detect and map intermediate ischemia. Those results indicate that EWI could be used to assess the conduction properties of the myocardium, and detect its ischemic onset and disease progression entirely noninvasively.


Assuntos
Ecocardiografia/métodos , Sistema de Condução Cardíaco/diagnóstico por imagem , Isquemia/diagnóstico por imagem , Processamento de Sinais Assistido por Computador , Algoritmos , Animais , Cães , Sistema de Condução Cardíaco/fisiologia , Humanos , Isquemia/fisiopatologia , Masculino , Contração Miocárdica/fisiologia
19.
IEEE Trans Med Imaging ; 28(4): 477-86, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19272985

RESUMO

The abdominal aortic aneurysm (AAA) is a common vascular disease. The current clinical criterion for treating AAAs is an increased diameter above a critical value. However, the maximum diameter does not correlate well with aortic rupture, the main cause of death from AAA disease. AAA disease leads to changes in the aortic wall mechanical properties. The pulse-wave velocity (PWV) may indicate such a change. Because of limitations in temporal and spatial resolution, the widely used foot-to-foot method measures the global, instead of regional, PWV between two points at a certain distance in the circulation. However, mechanical properties are nonuniform along the normal and pathological (e.g., the AAA and atherosclerosis) arteries; thus, such changes are typically regional. Pulse-wave imaging (PWI) has been developed by our group to map the pulse-wave propagation along the abdominal aorta in mice in vivo. By using a retrospective electrocardiogram (ECG) gating technique, the radio-frequency (RF) signals over one cardiac cycle were obtained in murine aortas at the extremely high frame rate of 8 kHz and with a field-of-view (FOV) of 12 x 12 mm(2). The velocities of the aortic wall were estimated using an RF-based speckle tracking method. An Angiotensin II (AngII) infusion-based AAA model was used to simulate the human AAA case. Sequences of wall velocity images can noninvasively and quantitatively map the propagation of the pulse wave along the aortic wall. In the normal and sham aortas, the propagation of the pulse wave was relatively uniform along the wall, while in the AngII-treated aortas, the propagation was shown to be nonuniform. There was no significant difference ( p > 0.05) in the PWV between sham (4.67 +/- 1.15 m/s, n=5) and AngII-treated (4.34 +/- 1.48 m/s, n=17) aortas. The correlation coefficient of the linear regression was significantly higher ( p < 0.005) in the sham aortas (0.89 +/- 0.03, n=5 ) than in the AngII-treated ones (0.61 +/- 0.15, n=17). The wall velocities induced by the pulse wave were lower and the pulse wave moved nonuniformly along the AngII-treated aorta ( p < 0.005), with the lowest velocities at the aneurysmal regions. The discrepancy in the regional wall velocity and the nonuniform pulse-wave propagation along the AngII-treated aorta indicated the inhomogeneities in the aortic wall properties, and the reduced wall velocities indicated stiffening of the aneurysmal wall. This novel technique may thus constitute an early detection tool of vascular degeneration as well as serve as a suitable predictor of AAA rupture, complementary to the current clinical screening practice.


Assuntos
Aorta Abdominal , Aneurisma da Aorta Abdominal , Interpretação de Imagem Assistida por Computador/métodos , Processamento de Sinais Assistido por Computador , Ultrassonografia/métodos , Angiotensina II , Animais , Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/diagnóstico , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Simulação por Computador , Interpretação Estatística de Dados , Modelos Animais de Doenças , Eletrocardiografia , Humanos , Modelos Lineares , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Tempo
20.
Echocardiography ; 25(5): 482-8, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18279402

RESUMO

BACKGROUND: Noninvasive and accurate assessment of mitral valve anatomy has become integral in the presurgical evaluation of patients with mitral valve prolapse (MVP). Recently developed real time three-dimensional (RT3D) ultrasound allows online acquisition, rendering, and can provide accurate information on cardiac structures. We sought to evaluate the feasibility of RT3D for the assessment of MVP segments when compared with transesophageal echocardiography (TEE) and intraoperative findings. METHODS: We examined 42 patients with MVP using RT3D, two-dimensional (2D) transthoracic echocardiography (TTE) and TEE. For RT3D analysis, cropping planes were used to slice the 3D volume on line to visualize the prolapsed segments of the mitral valve leaflets. The mitral valve was divided into six segments based on the American Society of Echocardiography's recommendations. Two experienced cardiologists evaluated echocardiographic images. RESULTS: Adequate RT3D images of the mitral valve were acquired in 40 out of 42 patients. The sensitivity and specificity of RT3D for defining prolapsed segments when compared with TEE were 95% and 99%, respectively (anterior leaflet: 96% and 99%, posterior leaflets: 93% and 100%, respectively). The sensitivity and specificity of TTE were 93% and 97%, respectively (anterior leaflet: 96% and 98%, posterior leaflets: 90% and 97%, respectively). Interobserver agreement for RT3D (Kappa 0.95, 95% confidence interval [CI] 0.91-1.00) was significantly greater than for TTE (Kappa 0.85, 95% CI 0.78-0.93) (P < 0.05). The elapsed time for completion of RT3D (14.4 +/- 2.8 min) was shorter than for TEE (26.4 +/- 4.7 min, P < 0.0001) and TTE (19.0 +/- 3.1 min, P< 0.0001). CONCLUSIONS: RT3D is fast, accurate, and highly reproducible for assessing MVP.


Assuntos
Ecocardiografia Tridimensional/instrumentação , Prolapso da Valva Mitral/diagnóstico por imagem , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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