RESUMO
Pathological cardiac hypertrophy is a key contributor to heart failure, and the molecular mechanisms underlying honokiol (HNK)-mediated cardioprotection against this condition remain worth further exploring. This study aims to investigate the effect of HNK on angiotensin II (Ang II)-induced myocardial hypertrophy and elucidate the underlying mechanisms. Sprague-Dawley rats were exposed to Ang II infusion, followed by HNK or vehicle treatment for 4 weeks. Our results showed that HNK treatment protected against Ang II-induced myocardial hypertrophy, fibrosis and dysfunction in vivo and inhibited Ang II-induced hypertrophy in neonatal rat ventricular myocytes in vitro. Mechanistically, HNK suppressed the Ang II-induced Nur77 expression at the transcriptional level and promoted ubiquitination-mediated degradation of Nur77, leading to dissociation of the Nur77-LKB1 complex. This facilitated the translocation of LKB1 into the cytoplasm and activated the LKB1-AMPK pathway. Our findings suggest that HNK attenuates pathological remodelling and cardiac dysfunction induced by Ang II by promoting dissociation of the Nur77-LKB1 complex and subsequent activation of AMPK signalling. This study uncovers a novel role of HNK on the LKB1-AMPK pathway to protect against cardiac hypertrophy.
Assuntos
Proteínas Quinases Ativadas por AMP , Compostos Alílicos , Angiotensina II , Compostos de Bifenilo , Fenóis , Ratos , Animais , Angiotensina II/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Ratos Sprague-Dawley , Cardiomegalia/metabolismo , Miócitos Cardíacos/metabolismoRESUMO
OBJECTIVE: The aim of the work described here was to evaluate strain and morphological change of the left ventricle in Sprague Dawley (SD) rats at different exercise intensities by 2-D speckle tracking imaging (STI). METHODS: Seventy-two 8-wk-old SD rats were divided into four groups on the basis of exercise intensity: sedentary (SED), low-intensity running, medium-intensity running (MIR) and high-intensity running (HIR). Each group was further sub-divided into three groups of different exercise lengths: 1, 4 and 8 wk. The structural measurements of the left ventricle and left ventricular ejection fraction (LVEF) were obtained by echocardiography. Systolic peak values of global longitudinal, circumferential and radial strains (GLS, GCS and GRS) were obtained. Histopathological results of the cross-sectional area (CSA) of myocardial cells, collagen volume fraction (CVF) of the myocardium and perivascular collagen area (PVCA) were also observed. RESULTS: Structural measurements of the left ventricle and LVEF did not change with different exercise intensities or lengths. GLS of the HIR8 wk sub-group was significantly lower than those of the SED8 wk and MIR8 wk sub-groups. Conversely, the GLS and GCS of the HIR8 wk sub-group were lower than those of the HIR1 wk and HIR4 wk sub-groups. Histopathologically, the CSA of myocardial cells significantly increased across all HIR sub-groups and the MIR4 wk and MIR8 wk sub-groups. CVFendo and PVCA were also significantly increased in the HIR4 wk and HIR8 wk sub-groups. The HIR8 wk group also had regional swelling and ill-defined boundaries of myocardial cells. CONCLUSION: Prolonged, high-intensity exercise may lead to exercise-induced injury of the myocardium. Two-dimensional STI can be used as a non-invasive early detection method for exercise-induced injury of myocardial function, compared with LVEF.
Assuntos
Ecocardiografia Tridimensional , Disfunção Ventricular Esquerda , Ratos , Animais , Função Ventricular Esquerda , Volume Sistólico , Ecocardiografia Tridimensional/métodos , Ratos Sprague-Dawley , ColágenoRESUMO
BACKGROUND: Myocardial work acquired by echocardiography has emerged as a novel method to evaluate myocardial function. We investigated global and segmental myocardial work in hypertension (HT) among patients with different patterns of left ventricular (LV) geometry in order to analyze the contribution of segmental myocardial work to global myocardial work. METHODS AND RESULTS: One hundred twenty-five patients with HT were divided into 4 groups: normal geometry (NG), concentric remodeling (CR), concentric hypertrophy (CH) and eccentric hypertrophy (EH). Longitudinal strain (LS) and the following indices were obtained by echocardiography: myocardial work index (MWI), myocardial constructive work (MCW), myocardial wasted work (MWW), and myocardial work efficiency (MWE). The global longitudinal strain (GLS) decreased gradually among the groups: NG, CR, CH and EH (P < 0.001). Global MWI (GWI) and global MCW (GCW) did not change across the different LV remodeling groups. Global MWW (GWW) increased and global MWE (GWE) decreased in both CH and EH group (P < 0.001). The LS of basal and middle regions reduced gradually in all HT subgroups, while apical LS decreased only in the CH and EH groups (P < 0.001). Basal MWI and MCW decreased in the CH and EH groups (P = 0.025, 0.007, respectively). Apical MWI and MCW increased in the NG and CR groups (P = 0.015, 0.044, respectively), with a decreasing trend in the CH and EH groups. All segmental MWW elevated and MWE reduced significantly in the CH and EH groups (P < 0.001). Univariate and multivariate logistic regression analyses demonstrated a significant association between left atrial volume index (LAVI), GLS, GWE and LV hypertrophy. At the receiver operating characteristic (ROC) analysis, optimal cutoff values of GLS, Apical LS, GWE and Apical MWE discriminating LV hypertrophy were 0.9072, 0.8049, 0.8325 and 0.7414, respectively. CONCLUSION: Apical myocardial work increases in the early stages of LV remodeling, likely as a compensatory mechanism to maintain normal global myocardial work. Segmental myocardial work analysis offers a reliable means to explore the distribution of myocardial impairment in hypertensive patients at different LV remodeling stages.
Assuntos
Hipertensão , Humanos , Hipertensão/complicações , Hipertensão/diagnóstico , Miocárdio , Ecocardiografia/métodos , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Ventrículos do Coração/diagnóstico por imagem , Função Ventricular Esquerda , Volume SistólicoRESUMO
We investigated myocardial work in hypertension (HT) among patients with different left ventricular ejection fraction (LVEF) to analyze the contribution of segmental myocardial work to global myocardial work. 114 patients with HT were divided into 4 groups: HTsnEF ("supra-normal" EF, > 65%); HTnEF ("normal" EF, 60-65%); HTmEF (designed as "middle" EF, 50-60%, within an abnormal LV geometry); HTrEF (reduced EF, < 50%). Longitudinal strain (LS) and myocardial work indices were obtained by echocardiography: myocardial work index (MWI), constructive work (MCW), wasted work (MWW), myocardial work efficiency (MWE), and percentages of apical work were calculated (PApi-MWI, PApi-MCW). Global LS (GLS) and global MWE (GWE) decreased in HTmEF and HTrEF groups. Global MWI(GWI) and MCW(GCW) increased in HTsnEF and HTnEF groups, and subsequently decreased, particularly in HTrEF group (P < 0.05). GWW increased in all HT subgroups. All segmental MWI and MCW were elevated or preserved initially in HTsnEF and HTnEF groups, and subsequently decreased, obviously in basal and middle segments in HTrEF group (P < 0.05). All segmental MWW increased and MWE decreased in HTmEF and HTrEF groups (P < 0.05). PApi-MWI and PApi-MCW increased initially, and subsequently decreased in HTmEF group, and elevated significantly in HTrEF group. Correlation analysis revealed a close connection of GLS and myocardial work parameters with LVEF. Apical myocardial work increased at the early stages of hypertensive systolic dysfunction, as a compensatory mechanism. Segmental myocardial work analysis added value to explore the distribution of myocardial impairment.
Assuntos
Hipertensão , Função Ventricular Esquerda , Humanos , Volume Sistólico , Valor Preditivo dos Testes , Miocárdio , Hipertensão/complicações , Hipertensão/diagnósticoRESUMO
BACKGROUND AND AIMS: Vulnerable plaques are closely related to ischemic stroke. To investigate the diagnostic value of multimodal plaque vulnerability ultrasound scoring system (PV-USS) using histopathology as the gold standard. METHODS: A total of 45 subjects who would be underwent carotid endarterectomy were recruited. The postoperative specimens were examined by histopathology. All responsible plaques were scanned dynamically in multiple sections by carotid ultrasound to measure maximum thickness and lumen stenotic degree, as well as, the echo, homogeneity, surface morphology, and echo type were observed. The above two-dimensional (2D) ultrasonic features were systematically scored, that is, PV-USS2D . Combined with contrast-enhanced ultrasonography (CEUS), neovascularization grade in plaque was scored, which is PV-USS2D+CEUS . RESULTS: According to the pathological results, 45 subjects were divided into vulnerable plaque group (27 cases, 60%) and non-vulnerable plaque group (18 cases, 40%). PV-USS2D and PV-USS2D+CEUS in vulnerable plaque group were higher than those in non-vulnerable plaque group (PV-USS2D : 9.44 ± 2.10 vs 7.22 ± 1.73; PV-USS2D+CEUS: 12.37 ± 2.10 vs 8.28 ± 1.81, P < .001). ROC curve analysis showed that the AUC of PV-USS2D and PV-USSCEUS was 0.783 and 0.929, respectively (P < .001). The best cutoff values of PV-USS2D and PV-USS2D+CEUS were, respectively, 9.5 (the maximum Youden index was 0.425, the sensitivity was 48.1%, the specificity was 94.4%) and 10.5 (the maximum Youden index was 0.667, the sensitivity was 77.8%, the specificity was 88.9%). CONCLUSIONS: Ultrasound scoring system may be used as an effective method to evaluate the vulnerability of plaque. The diagnostic efficiency of PV-USS2D+CEUS is more higher than PV-USS2D .
Assuntos
Artérias Carótidas , Endarterectomia das Carótidas , Ultrassonografia das Artérias Carótidas , Humanos , Endarterectomia das Carótidas/efeitos adversos , Placa Aterosclerótica/diagnóstico por imagem , Artérias Carótidas/diagnóstico por imagem , Artérias Carótidas/patologia , Estudos Prospectivos , Masculino , FemininoRESUMO
Objective: To evaluate the effects of antiretrovirals on cardiovascular function and some biochemical indexes in gestational female rats. Methods: Nineteen 9-week-old female and six 10-week-old male SD rats were divided into normal control group (CON) and highly active antiretroviral therapy group (HARRT), 9/10 female rats and 3 male rats were combined into one cage, totally 2 cages. Female rats in CON group were intragastrically given with normal saline (NS, 10 ml/kg) every morning and evening, while female rats in HARRT group were treated with equal volume antiretrovirals (AZT 31.25 mg/kg + 3TC 15.63 mg/kg + LPV/r (41.67/10.42) mg/kg) for 3 months. The body weight and survival rate of female rats were recorded. Echocardiography and multichannel physiological recorder were used to detect arterial blood pressure and cardiac hemodynamic parameters. The levels of blood glucose, blood lipids, myocardial enzymes and liver enzymes were detected by corresponding kits. Myocardial collagen fibers were observed by Masson staining and the ultrastructure of myocardial cells were observed by transmission electron microscopy. Results: All female rats in CON group survived (9/9), while only 6 rats in HARRT group survived (6/10). Compared with CON group, the body weight of female rats in HAART group was decreased significantly(Pï¼0.01); the levels of left ventricular end diastolic diameter (LVDd), interventricular septal thickness (IVST), thickness of left ventricular posterior wall (LVPWT) , left atrial diameter (LAD) and arterial diastolic pressure were increased significantly (Pï¼0.05); the level of LVP+dP/dtmax was decreased (Pï¼0.01). The levels of triglyceride, creatine kinase, and glutamic oxaloacetic transaminase were decreased (Pï¼0.05 or Pï¼0.01), while the level of glucose was increased (Pï¼0.05). The collagen fibers were increased in myocardial tissue, and ultrastructure of myocardial cells was abnormal. Conclusion: Antiretrovirals during gestation can cause cardiovascular diseases in female rats.
Assuntos
Antirretrovirais , Cardiotoxicidade , Miócitos Cardíacos , Animais , Antirretrovirais/efeitos adversos , Peso Corporal , Colágeno , Feminino , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/ultraestrutura , Gravidez , Ratos , Ratos Sprague-DawleyRESUMO
OBJECTIVE: Transthoracic echocardiography (TTE) is generally recognized as the top choice for detecting myocardial and cardiac cavity lesions. Sonographers mostly focus on myocardium, cardiac cavity and cardiac hemodynamics, whereas the abnormal extra-cardiac lesions are easily remain unrecognized. The aim of this study was to investigate the ultrasonic image features in abnormal extra-cardiac lesions and the value of TTE in the detection of extra-cardiac lesions. METHODS: 49 cases of abnormal extra-cardiac lesion detected by TTE from January 2014 to December 2019 were collected, which were confirmed by surgical pathology. The two-dimensional ultrasonic characteristics and the relationships with the cardiac and great vessels were summarized on the basis of multi-view by TTE. All patients were also examined by computed tomography (CT). RESULTS: In 49 patients with abnormal extra-cardiac lesions, 37 malignant cases and 12 benign cases were included. There were 41 cases (41/49, 86.67%) of mediastinal lesions and 8 cases (8/49, 16.33%) of lung lesions. The maximum diameter ranged from 3.2 cm to 13.66 cm, and the median diameter was about 7.4 cm, among which 29 cases (29/49, 59.18%) were larger than 5 cm. 4 cases (4/49, 8.16%) of cystic anechoic lesions were pericardial cyst. 2 cases (2/49, 4.08%) of cystic-solid echogenic lesions were teratoma. The remaining 43 cases (43/49, 87.76%) presented as solid hypoechoic or heterogeneous masses. 6 cases compressed the heart and 21 cases encroached on the heart and vessels. Diagnosis coincidence rates of TTE and CT were respectively 77.55% and 93.88%, with a statistical difference (p = 0.012). CONCLUSION: Although the diagnostic coincidence rate of TTE is slightly lower than that of CT, TTE has certain diagnostic value for extra-cardiac lesions.
Assuntos
Ecocardiografia , Tomografia Computadorizada por Raios X , Ecocardiografia/métodos , Hemodinâmica , HumanosRESUMO
BACKGROUND: Myocardial fibrosis plays an important role in the pathogenesis of hypertensive cardiac dysfunction, and myocardial strain could detect early systolic abnormalities when left ventricular ejection fraction (LVEF) is preserved. The aim of this study was to investigate the characteristics of left ventricular multidirectional strain during different stages of heart dysfunction and the possible morphological basis in spontaneously hypertensive rats (SHRs). METHODS: SHRs and Wistar-Kyoto (WKY) rats were randomly divided into cages and observed for 3-25 months. Echocardiographic measurements, LV + dp/dtmax and left ventricular end-diastolic pressure (LVEDP), and histological collagen volume fraction (CVF) were observed in all rats. RESULTS: According to LVEF and LVEDP, SHRs were divided into normal cardiac function group (group A), diastolic dysfunction group (group B1), and systolic dysfunction group (group B2). In group A, myocardial strain and CVF showed no difference compared with the control group. In group B1, global longitudinal strain (GLS) and endocardial longitudinal strain (SL-endo) were lower than those in group A CVF-endo was increased (all P < 0.05). In group B2, global and layer-specific strain decreased significantly, along with the increased CVF-endo and CVF-epi (all P < 0.05). The decrease of GLS and SL-endo was moderately correlated with the increase of CVF-endo. The reduction of LVEF was correlated with the decrease of SC-endo (r = 0.65, P < 0.01). CONCLUSIONS: Pathological myocardial fibrosis associated with hypertension develops from the inner to outer layer of myocardium, which is coincident with the impairment of myocardial deformation, where longitudinal strain is involved firstly and LVEF declines when all directions of strain are reduced.
Assuntos
Cardiomiopatias , Hipertensão , Disfunção Ventricular Esquerda , Animais , Fibrose , Hipertensão/complicações , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Volume Sistólico , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/etiologia , Função Ventricular EsquerdaRESUMO
BACKGROUND: Cardiac remodeling is one of the major risk factors for heart failure. In patients with type 2 diabetes, sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of the first hospitalization for heart failure, possibly through glucose-independent mechanisms in part, but the underlying mechanisms remain largely unknown. This study aimed to shed light on the efficacy of dapagliflozin in reducing cardiac remodeling and potential mechanisms. METHODS: Sprague-Dawley (SD) rats, induced by chronic infusion of Angiotensin II (Ang II) at a dose of 520 ng/kg per minute for 4 weeks with ALZET® mini-osmotic pumps, were treated with either SGLT2 inhibitor dapagliflozin (DAPA) or vehicle alone. Echocardiography was performed to determine cardiac structure and function. Cardiac fibroblasts (CFs) were treated with Ang II (1 µM) with or without the indicated concentration (0.5, 1, 10 µM) of DAPA. The protein levels of collagen and TGF-ß1/Smad signaling were measured along with body weight, and blood biochemical indexes. RESULTS: DAPA pretreatment resulted in the amelioration of left ventricular dysfunction in Ang II-infused SD rats without affecting blood glucose and blood pressure. Myocardial hypertrophy, fibrosis and increased collagen synthesis caused by Ang II infusion were significantly inhibited by DAPA pretreatment. In vitro, DAPA inhibit the Ang II-induced collagen production of CFs. Immunoblot with heart tissue homogenates from chronic Ang II-infused rats revealed that DAPA inhibited the activation of TGF-ß1/Smads signaling. CONCLUSION: DAPA ameliorates Ang II-induced cardiac remodeling by regulating the TGF-ß1/Smad signaling in a non-glucose-lowering dependent manner.
Assuntos
Antifibróticos/farmacologia , Compostos Benzidrílicos/farmacologia , Fibroblastos/efeitos dos fármacos , Glucosídeos/farmacologia , Hipertrofia Ventricular Esquerda/prevenção & controle , Proteínas Smad/metabolismo , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Fator de Crescimento Transformador beta1/metabolismo , Disfunção Ventricular Esquerda/prevenção & controle , Função Ventricular Esquerda/efeitos dos fármacos , Remodelação Ventricular/efeitos dos fármacos , Angiotensina II , Animais , Células Cultivadas , Modelos Animais de Doenças , Fibroblastos/metabolismo , Fibroblastos/patologia , Fibrose , Hipertrofia Ventricular Esquerda/induzido quimicamente , Hipertrofia Ventricular Esquerda/metabolismo , Hipertrofia Ventricular Esquerda/patologia , Masculino , Miocárdio/metabolismo , Miocárdio/patologia , Ratos Sprague-Dawley , Transdução de Sinais , Disfunção Ventricular Esquerda/induzido quimicamente , Disfunção Ventricular Esquerda/metabolismo , Disfunção Ventricular Esquerda/patologiaRESUMO
Diabetic cardiac fibrosis increases ventricular stiffness and facilitates the occurrence of diastolic dysfunction. Retinoid X receptor (RXR) plays an important role in cardiac development and has been implicated in cardiovascular diseases. In the present study, we investigated the effects of RXR agonist treatment on streptozotocin (STZ)-induced diabetic cardiomyopathy (DCM) and the underlying mechanism. Sprague-Dawley (SD) rats induced by STZ injection were treated with either RXR agonist bexarotene (Bex) or vehicle alone. Echocardiography was performed to determine cardiac structure and function. Cardiac fibroblasts (CFs) were treated with high glucose (HG) with or without the indicated concentration of Bex or the RXR ligand 9-cis-retinoic acid (9-cis-RA). The protein abundance levels were measured along with collagen, body weight (BW), blood biochemical indexes and transforming growth factor-ß (TGF-ß) levels. The effects of RXRα down-regulation by RXRα small interfering RNA (siRNA) were examined. The results showed that bexarotene treatment resulted in amelioration of left ventricular dysfunction by inhibiting cardiomyocyte apoptosis and myocardial fibrosis. Immunoblot with heart tissue homogenates from diabetic rats revealed that bexarotene activated liver kinase B1 (LKB1) signaling and inhibited p70 ribosomal protein S6 kinase (p70S6K). The increased collagen levels in the heart tissues of DCM rats were reduced by bexarotene treatment. Treatment of CFs with HG resulted in significantly reduced LKB1 activity and increased p70S6K activity. RXRα mediated the antagonism of 9-cis-RA on HG-induced LKB1/p70S6K activation changes in vitro. Our findings suggest that RXR agonist ameliorates STZ-induced DCM by inhibiting myocardial fibrosis via modulation of the LKB1/p70S6K signaling pathway. RXR agonists may serve as novel therapeutic agents for the treatment of DCM.
Assuntos
Bexaroteno/administração & dosagem , Cardiomiopatias/tratamento farmacológico , Diabetes Mellitus Tipo 1/complicações , Proteínas Serina-Treonina Quinases/metabolismo , Receptores X de Retinoides/agonistas , Quinases Proteína-Quinases Ativadas por AMP , Animais , Cardiomiopatias/etiologia , Cardiomiopatias/genética , Cardiomiopatias/metabolismo , Fibrose/tratamento farmacológico , Fibrose/etiologia , Fibrose/genética , Fibrose/metabolismo , Humanos , Masculino , Proteínas Serina-Treonina Quinases/genética , Ratos , Ratos Sprague-Dawley , Receptores X de Retinoides/genética , Receptores X de Retinoides/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/genética , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , EstreptozocinaRESUMO
BACKGROUND: This study is aimed at investigating myocardial multi-directional systolic deformation in hypertensive with different left ventricular ejection fraction (LVEF), and exploring its contribution to LVEF. METHODS: One hundred and twenty-three patients with primary hypertension (HT) were divided into group A (LVEF ≥ 55%), group B (45% ≤ LVEF < 50%, or 50% ≤ LVEF < 55% + LVEDVI ≥ 97 ml/m2), and group C (LVEF < 45%). Two-dimensional strain echocardiography (2DSE) including LV longitudinal strain (SL), radial strain (SR) and circumferential strain (SC) were measured. RESULTS: SL decreased gradually from group A, B to C (all p < 0.05) while SR and SC were reduced only in group B and C (all p < 0.05). All strain measurements correlated to LVEF, with the strongest correlation in SC (r = -0.82, p < 0.01) and the second in SL (r = -0.76). The diastolic E/e increased from group A, B to C. CONCLUSIONS: Left ventricular multi-directional deformation correlated well to LVEF in hypertension and particularly SC, indicating that it was SC, not SL or SR, that makes the prominent contribution to left ventricular pump function.
Assuntos
Hipertensão/fisiopatologia , Volume Sistólico/fisiologia , Função Ventricular Esquerda/fisiologia , Adulto , Idoso , Estudos de Casos e Controles , Ecocardiografia , Feminino , Humanos , Hipertensão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Resistência Vascular/fisiologiaRESUMO
OBJECTIVES: To explore expressions of matrix metalloproteinase-1 (MMP-1), tissue inhibitor of metalloproteinases-1 (TIMP-1) and transforming growth factor-ß1 (TGF-ß1) in valve tissue of rheumatic heart disease (RHD), and to analyzed their roles in RHD. METHODS: The expressions of MMP-1, TIMP-1 and TGF-ß1 proteins and mRNAs were tested by Western blot and RT-PCR methods in valve tissues in participants with (experimental group, n=30) and without RHD (control group, n=15). Collagen fibers were detected by Masson staining, and collagen volume fraction (CVF) was caculated. The correlations of CVF and the expressions of MMP-1, TIMP-1 and TGF-ß1 were analyzed. RESULTS: The collagen fibers, CVF, and the protein and mRNA expressions of MMP-1 and TGF-ß1 in experimental group were higher than those in control group, while the protein and mRNA expressions of TIMP-1 in experimental group were lower than those in control group. The expression of TIMP-1 was negatively correlated with TGF-ß1 and CVF in valve tissues, while MMP-1 was positively correlated with them. The expression of TGF-ß1 was positively correlated with CVF in valve tissues. CONCLUSIONS: MMP-1, TIMP-1 and TGF-ß1 contribute to the progression of fibrosis in RHD.
Assuntos
Valvas Cardíacas/metabolismo , Metaloproteinase 1 da Matriz/metabolismo , Cardiopatia Reumática/metabolismo , Inibidor Tecidual de Metaloproteinase-1/metabolismo , Fator de Crescimento Transformador beta1/metabolismo , Fibrose , Humanos , RNA MensageiroRESUMO
OBJECTIVES: Two-dimensional strain echocardiography (2DSE) technique has enabled accurate quantification of regional myocardial function. This experimental study was aimed to investigate the value of 2DSE in detection of segmental regional myocardial dysfunction induced by fibrosis following myocardial infarction in a small animal (rat) model. METHODS: A rat model of myocardial infarction was established by ligation of the proximal left anterior descending coronary artery in 17 SD rats. Regional myocardial function was detected by 2DSE at baseline and 4-weeks post-infarction, including end-systolic radial strain and strain rate (SR and SrR) and end-systolic circumferential strain and strain rate (SC and SrC) of each of six segments at papillary level. According to the size of scar found by histologic Masson staining, the optimal cutoff points of parameters for detecting scar area were analyzed and the sensitivity and specificity of every parameter to detect myocardial scar were obtained using ROC. RESULTS: (1) Comparing with parameters measured at baseline, there were significant decreases in SR, SrR, SC and SrC of each segment at 4 weeks post-infarction, with the worst in the infarct area (32.90 ± 8.79 vs 11.18 ± 3.89, 6.28 ± 1.35 vs 3.18 ± 0.47, -14.46 ± 2.21 vs -6.30 ± 2.17 and 4.93 ± 0.95 vs 2.59 ± 1.16, respectively) (all P < 0.05). (2)By 4 weeks, the myocardium of infarct area (anteroseptum, anterior and anterolateral) had fibrosis (31.33 ± 9.89, 73.42 ± 13.21 and 13.99 ± 3.24%, respectively) with minimal fibrosis in inferoseptal segment (0.32 ± 0.19%), no fibrosis was found in the inferior and inferolateral segments. (3)Significant negative correlations were found between the size of segmental scar and 2DSE parameters (r-value -0.61 ~ -0.80, all P < 0.01) with the strongest correlation in SR. SR less than 10% has 84% sensitivity and 98% specificity for detecting segments of scar area greater than 30% with AUC = 0.97. CONCLUSIONS: 2DSE is able to assess regional myocardial dysfunction in a rat model of myocardial infarction and has high accuracy in detecting infarct segments with scar area greater than 30%.
Assuntos
Cicatriz/diagnóstico por imagem , Ecocardiografia/métodos , Fibrose Endomiocárdica/diagnóstico por imagem , Infarto do Miocárdio/diagnóstico por imagem , Animais , Cicatriz/etiologia , Cicatriz/fisiopatologia , Módulo de Elasticidade , Fibrose Endomiocárdica/etiologia , Fibrose Endomiocárdica/fisiopatologia , Masculino , Infarto do Miocárdio/complicações , Infarto do Miocárdio/fisiopatologia , Ratos , Ratos Sprague-Dawley , Resultado do TratamentoRESUMO
BACKGROUND: Tissue Doppler (TD) echocardiographic imaging of mitral and tricuspid annulus has been applied to assess right ventricular (RV) and left ventricular (LV) function in many cardiac diseases, but its clinical application, including response to long-term targeted therapy in patients with idiopathic pulmonary hypertension (PH), has not been addressed. METHODS: Seventy patients with idiopathic PH were compared with 35 age-matched control subjects to examine myocardial velocities by TD. Of these, 35 patients underwent repeat imaging after long-term targeted therapy. In addition, 50 consecutive patients with idiopathic PH with simultaneous right-heart catheterization and echocardiography were examined. RESULTS: No significant differences were noted between PH patients and the control group in lateral mitral annulus systolic velocity and early diastolic velocity (Ea) by TD, but septal velocities were significantly lower (p < 0.01). With targeted therapy, myocardial velocities at the septum and RV free wall increased significantly (p < 0.05). Likewise, E/Ea ratio increased, albeit still in the normal range. In all 50 patients with invasive measurements, lateral E/Ea ratio readily identified normal mean pulmonary capillary wedge pressure (PCWP). CONCLUSIONS: TD imaging of the lateral mitral annulus can reliably predict the presence of normal/reduced mean PCWP in patients with idiopathic PH, and track the improvement in RV function and LV filling with long-term targeted therapy.
Assuntos
Ecocardiografia Doppler de Pulso , Valvas Cardíacas/diagnóstico por imagem , Valvas Cardíacas/fisiopatologia , Ventrículos do Coração/fisiopatologia , Hipertensão Pulmonar/diagnóstico por imagem , Hipertensão Pulmonar/fisiopatologia , Adulto , Velocidade do Fluxo Sanguíneo/fisiologia , Débito Cardíaco/fisiologia , Feminino , Ventrículos do Coração/diagnóstico por imagem , Humanos , Hipertensão Pulmonar/terapia , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Pressão Propulsora Pulmonar/fisiologiaRESUMO
Echocardiography is the imaging modality most frequently used to assess left ventricular ejection fraction (EF). However, the accuracy of the EF can be limited by the technical quality of the examination and observer variability. Recently, tissue Doppler was applied to acquire signals of myocardial systolic function, including systolic ejection velocity (S(a)) and the systolic isovolumic acceleration rate (IVA). In that regard, IVA was reported in animal studies to be the ideal noninvasive index, because it was not affected by preload and afterload and provided a reliable assessment of contractility when examined against invasive gold standards. However, a paucity of data is available about its clinical application. We undertook this investigation to examine S(a) and IVA in 40 normal subjects and 52 patients with depressed EF referred for echocardiographic examination, aiming to identify the signal with the highest reproducibility and the most accurate detection of depressed EF. S(a) had the least inter- and intraobserver variabilities (3 +/- 1.5% and 2.5 +/- 1%, respectively), and IVA had the highest variability (8.1 +/- 2.1% and 6.8 +/- 2%, respectively). Although S(a) and IVA were significantly lower in patients with depressed EF (p <0.05), S(a) had the best correlation with EF (r = 0.65, p <0.03) and S(a) of <7 cm/s was the most accurate (p <0.05 vs IVA) in identifying patients with EF <45% (sensitivity 93%, specificity 87%). In conclusion, S(a) velocity is the most suitable signal for clinical application as a surrogate for left ventricular EF, given its accuracy and reproducibility.
Assuntos
Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/fisiopatologia , Ecocardiografia Doppler/métodos , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/fisiopatologia , Volume Sistólico/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Função Ventricular , Pressão Ventricular/fisiologiaRESUMO
We sought to examine the hemodynamic determinants and clinical application of the peak acceleration rate of early (Ea) diastolic velocity of the mitral annulus by tissue Doppler. Simultaneous left atrial and left ventricular (LV) catheterization and Doppler echocardiography were performed in 10 dogs. Preload was altered using volume infusion and caval occlusion, whereas myocardial lusitropic state was altered with dobutamine and esmolol. The clinical application was examined in 190 consecutive patients (55 control, 41 impaired relaxation, 46 pseudonormal, and 48 restrictive LV filling). In addition, in 60 consecutive patients, we examined the relation between it and mean wedge pressure with simultaneous Doppler echocardiography and right heart catheterization. In canine studies, a significant positive relation was present between peak acceleration rate of Ea and transmitral pressure gradient only in the stages with normal or enhanced LV relaxation, but with no relation in the stages where the time constant of LV relaxation (tau) was > or =50 ms. Its hemodynamic determinants were tau, LV minimal pressure, and transmitral pressure gradient. In clinical studies, peak acceleration rate of Ea was significantly lower in patients with impaired LV relaxation irrespective of filling pressures (P < 0.001) and with similar accuracy to peak Ea velocity (area under the curve for septal and lateral peak acceleration rates: both 0.78) in identifying these patients. No significant relation was observed between peak acceleration rate and mean wedge pressure. Peak acceleration rate of Ea appears to be a useful index of LV relaxation but not of filling pressures and can be applied to identify patients with impaired LV relaxation irrespective of their filling pressures.
Assuntos
Diástole , Valva Mitral/diagnóstico por imagem , Função Ventricular Esquerda , Animais , Velocidade do Fluxo Sanguíneo , Cães , Ecocardiografia Doppler/métodos , Humanos , Pessoa de Meia-Idade , Pressão Propulsora Pulmonar , Análise de Regressão , Fatores de Tempo , Pressão VentricularRESUMO
The aim of this study was to examine the effect of age on left ventricular (LV) systolic function in normal healthy adults. Eighty consecutive subjects without cardiovascular disease underwent standard and tissue Doppler (TD) echocardiographic imaging. LV systolic function was assessed by load-dependent indices as ejection fraction (EF) and myocardial systolic velocities by TD as well as by the load-independent index, systolic isovolumic acceleration rate (IVA). None of the echocardiographic measurements of systolic function declined with age (mean IVA for the group, 286 +/- 123 cm s(-2); IVA vs. age, r = 0.21, P = 0.1). Likewise, LV end diastolic dimension, wall thickness, mass and left atrial maximum volume were not significantly related to age. On the other hand, as previously reported, echocardiographic indices of diastolic function showed a significant decline with age (P < 0.05). When the group was stratified by gender, isovolumic velocity and acceleration were higher in men than women, but the differences were not significant (P = 0.12 and 0.37, respectively). No significant relation was observed between age and measurements of LV systolic function by regression analysis in women (P > 0.1). However, in men, a positive correlation was noted between average IVA and age (r = 0.63, P = 0.007). In conclusion, age is not associated with a change in cardiac structure and LV systolic function, but is accompanied by a decline in echocardiographic indices of diastolic function. With respect to gender, age does not appear to influence LV systolic function in women, but is associated with an increase in IVA and septal systolic ejection in men.