Exercise Training Reduces Inflammation and Fibrosis and Preserves Myocardial Function and Perfusion in a Model of Chronic Chagas Cardiomyopathy. / Treinamento Físico Reduz a Inflamação e a Fibrose e Preserva a Função e a Perfusão Miocárdica em um Modelo de Cardiomiopatia Chagásica Crônica.

BACKGROUND: Chronic Chagas cardiomyopathy (CCC) is caused by an inflammatory process induced by Trypanosoma cruzi, which leads to myocarditis with reactive and reparative fibrosis. CCC progresses with myocardial perfusion abnormalities and histopathological events that affect cardiorespiratory fitness (CRF). OBJECTIVES: We evaluated the effects of aerobic physical training (APT) on myocardial perfusion and on morphological and functional impairments related with inflammation and fibrosis in Syrian hamsters with CCC. As a secondary objective, we analyzed the cross-sectional areas of the skeletal muscle. METHODS: Hamsters with CCC and their respective controls were divided into four groups: CCC sedentary, CCC-APT, sedentary control and APT control. Seven months after infection, the animals underwent echocardiography, myocardial perfusion scintigraphy and cardiopulmonary exercise testing. Moderate-intensity APT was performed for fifty minutes, five times a week, for eight weeks. Subsequently, the animals were reassessed. Histopathological analysis was conducted after the above-mentioned procedures. The level of significance was set at 5% in all analyses (p<0.05). RESULTS: CCC sedentary animals presented worse myocardial perfusion defects (MPD) over time, reduced left ventricle ejection fraction (LVEF) and showed more inflammation and fibrosis when compared to other groups (mixed ANOVA analysis). Conversely, APT was able to mitigate the progression of MPD, ameliorate inflammation and fibrosis and improve CRF efficiency in CCC-APT animals. CONCLUSIONS: Our study demonstrated that APT ameliorated cardiac dysfunction, MPD, and reduced inflammation and fibrosis in CCC hamster models. Additionally, CCC-SED animals presented skeletal muscle atrophy while CCC-APT animals showed preserved skeletal muscle CSA. Understanding APT's effects on CCC's pathophysiological dimensions is crucial for future research and therapeutic interventions.

FUNDAMENTO: A Cardiomiopatia Chagásica Crônica (CCC) é causada por um processo inflamatório induzido pelo Trypanosoma cruzi, que leva à miocardite com fibrose reativa e reparativa. A CCC progride com alterações de perfusão miocárdica e eventos histopatológicos que afetam a Aptidão Cardiorrespiratória (ACR). OBJETIVOS: Avaliamos os efeitos do Treinamento Físico Aeróbico (TFA) na perfusão miocárdica e nos comprometimentos morfológicos e funcionais relacionados à inflamação e fibrose em hamsters sírios com CCC. Como objetivo secundário, analisamos as áreas de secção transversa do músculo esquelético. MÉTODOS: Hamsters com CCC e seus respectivos controles foram divididos em quatro grupos: CCC sedentário, CCC-TFA, controle sedentário e controle TFA. Sete meses após a infecção, os animais foram submetidos à ecocardiografia, à cintilografia de perfusão miocárdica e ao teste de esforço cardiopulmonar. TFA de intensidade moderada foi realizado durante cinquenta minutos, cinco vezes por semana, por oito semanas. Posteriormente, os animais foram reavaliados. A análise histopatológica foi realizada após os procedimentos acima mencionados. O nível de significância foi estabelecido em 5% em todas as análises (p<0,05). RESULTADOS: Animais com CCC sedentários apresentaram piores Defeitos de Perfusão Miocárdica (DPM) ao longo do tempo, Fração de Ejeção do Ventrículo Esquerdo (FEVE) reduzida, e apresentaram mais inflamação e fibrose quando comparados aos demais grupos (análise ANOVA mista). Por outro lado, o TFA foi capaz de mitigar a progressão do DPM, atenuar a inflamação e a fibrose e melhorar a eficiência da ACR em animais CCC-TFA. CONCLUSÃO: Nosso estudo demonstrou que o TFA melhorou a disfunção cardíaca, DPM e reduziu a inflamação e a fibrose em modelos de hamster com CCC. Além disso, os animais CCC-SED apresentaram atrofia do músculo esquelético, enquanto os animais CCC-TFA apresentaram a AST do músculo esquelético preservada. Compreender os efeitos da TFA nas dimensões fisiopatológicas da CCC é crucial para futuras pesquisas e intervenções terapêuticas.

Treinamento Físico Reduz a Inflamação e a Fibrose e Preserva a Função e a Perfusão Miocárdica em um Modelo de Cardiomiopatia Chagásica Crônica / Exercise Training Reduces Inflammation and Fibrosis and Preserves Myocardial Function and Perfusion in a Model of Chronic Chagas Cardiomyopathy

Resumo Fundamento: A Cardiomiopatia Chagásica Crônica (CCC) é causada por um processo inflamatório induzido pelo Trypanosoma cruzi, que leva à miocardite com fibrose reativa e reparativa. A CCC progride com alterações de perfusão miocárdica e eventos histopatológicos que afetam a Aptidão Cardiorrespiratória (ACR). Objetivos: Avaliamos os efeitos do Treinamento Físico Aeróbico (TFA) na perfusão miocárdica e nos comprometimentos morfológicos e funcionais relacionados à inflamação e fibrose em hamsters sírios com CCC. Como objetivo secundário, analisamos as áreas de secção transversa do músculo esquelético. Métodos: Hamsters com CCC e seus respectivos controles foram divididos em quatro grupos: CCC sedentário, CCC-TFA, controle sedentário e controle TFA. Sete meses após a infecção, os animais foram submetidos à ecocardiografia, à cintilografia de perfusão miocárdica e ao teste de esforço cardiopulmonar. TFA de intensidade moderada foi realizado durante cinquenta minutos, cinco vezes por semana, por oito semanas. Posteriormente, os animais foram reavaliados. A análise histopatológica foi realizada após os procedimentos acima mencionados. O nível de significância foi estabelecido em 5% em todas as análises (p<0,05). Resultados: Animais com CCC sedentários apresentaram piores Defeitos de Perfusão Miocárdica (DPM) ao longo do tempo, Fração de Ejeção do Ventrículo Esquerdo (FEVE) reduzida, e apresentaram mais inflamação e fibrose quando comparados aos demais grupos (análise ANOVA mista). Por outro lado, o TFA foi capaz de mitigar a progressão do DPM, atenuar a inflamação e a fibrose e melhorar a eficiência da ACR em animais CCC-TFA. Conclusão: Nosso estudo demonstrou que o TFA melhorou a disfunção cardíaca, DPM e reduziu a inflamação e a fibrose em modelos de hamster com CCC. Além disso, os animais CCC-SED apresentaram atrofia do músculo esquelético, enquanto os animais CCC-TFA apresentaram a AST do músculo esquelético preservada. Compreender os efeitos da TFA nas dimensões fisiopatológicas da CCC é crucial para futuras pesquisas e intervenções terapêuticas.

Abstract Background: Chronic Chagas cardiomyopathy (CCC) is caused by an inflammatory process induced by Trypanosoma cruzi, which leads to myocarditis with reactive and reparative fibrosis. CCC progresses with myocardial perfusion abnormalities and histopathological events that affect cardiorespiratory fitness (CRF). Objectives: We evaluated the effects of aerobic physical training (APT) on myocardial perfusion and on morphological and functional impairments related with inflammation and fibrosis in Syrian hamsters with CCC. As a secondary objective, we analyzed the cross-sectional areas of the skeletal muscle. Methods: Hamsters with CCC and their respective controls were divided into four groups: CCC sedentary, CCC-APT, sedentary control and APT control. Seven months after infection, the animals underwent echocardiography, myocardial perfusion scintigraphy and cardiopulmonary exercise testing. Moderate-intensity APT was performed for fifty minutes, five times a week, for eight weeks. Subsequently, the animals were reassessed. Histopathological analysis was conducted after the above-mentioned procedures. The level of significance was set at 5% in all analyses (p<0.05). Results: CCC sedentary animals presented worse myocardial perfusion defects (MPD) over time, reduced left ventricle ejection fraction (LVEF) and showed more inflammation and fibrosis when compared to other groups (mixed ANOVA analysis). Conversely, APT was able to mitigate the progression of MPD, ameliorate inflammation and fibrosis and improve CRF efficiency in CCC-APT animals. Conclusions: Our study demonstrated that APT ameliorated cardiac dysfunction, MPD, and reduced inflammation and fibrosis in CCC hamster models. Additionally, CCC-SED animals presented skeletal muscle atrophy while CCC-APT animals showed preserved skeletal muscle CSA. Understanding APT's effects on CCC's pathophysiological dimensions is crucial for future research and therapeutic interventions.

What do we know about the role of menopause in cardiovascular autonomic regulation in hypertensive women?

OBJECTIVE: We investigated the systemic arterial hypertension effects on cardiovascular autonomic modulation and baroreflex sensitivity (BRS) in women with or without preserved ovarian function. METHODS: A total of 120 women were allocated into two groups: middle-aged premenopausal women (42 ± 3 y old; n = 60) and postmenopausal women (57 ± 4 y old; n = 60). Each group was also divided into two smaller groups (n = 30): normotensive and hypertensive. We evaluated hemodynamic and anthropometric parameters, cardiorespiratory fitness, BRS, heart rate variability (HRV), and blood pressure variability. The effects of hypertension and menopause were assessed using a two-way analysis of variance. Post hoc comparisons were performed using the Student-Newman-Keuls test. RESULTS: Comparing premenopausal groups, women with systemic arterial hypertension showed lower BRS (9.1 ± 4.4 vs 13.4 ± 4.2 ms/mm Hg, P < 0.001 ) and HRV total variance (1,451 ± 955 vs 2,483 ± 1,959 ms 2 , P = 0.005) values than normotensive; however, the vagal predominance still remained. On the other hand, both postmenopausal groups showed an expressive reduction in BRS (8.3 ± 4.2 vs 11.3 ± 4.8 ms/mm Hg, P < 0.001) and HRV characterized by sympathetic modulation predominance (low-frequency oscillations; 56% ± 17 vs 44% ± 17, P < 0.001), in addition to a significant increase in blood pressure variability variance (28.4 ± 14.9 vs 22.4 ± 12.5 mm Hg 2 , P = 0.015) compared with premenopausal groups. Comparing both postmenopausal groups, the hypertensive group had significantly lower values ​​of HRV total variance (635 ± 449 vs 2,053 ± 1,720 ms 2 , P < 0.001) and BRS (5.3 ± 2.8 vs 11.3 ± 3.2 ms/mm Hg) than the normotensive. CONCLUSIONS: Hypertensive middle-aged premenopausal women present HRV autonomic modulation impairment, but they still maintain a vagal predominance. After menopause, even normotensive women show sympathetic autonomic predominance, which may also be associated with aging. Furthermore, postmenopausal women with hypertension present even worse cardiac autonomic modulation.

Multifaceted Strategy Based on Automated Text Messaging After a Recent Heart Failure Admission: The MESSAGE-HF Randomized Clinical Trial.

Importance: Readmissions after an index heart failure (HF) hospitalization are a major contemporary health care problem. Objective: To evaluate the feasibility and efficacy of an intensive telemonitoring strategy in the vulnerable period after an HF hospitalization. Design, Setting, and Participants: This randomized clinical trial was conducted in 30 HF clinics in Brazil. Patients with left ventricular ejection fraction less than 40% and access to mobile phones were enrolled up to 30 days after an HF admission. Data were collected from July 2019 to July 2022. Intervention: Participants were randomly assigned to a telemonitoring strategy or standard care. The telemonitoring group received 4 daily short message service text messages to optimize self-care, active engagement, and early intervention. Red flags based on feedback messages triggered automatic diuretic adjustment and/or a telephone call from the health care team. Main Outcomes and Measures: The primary end point was change in N-terminal pro-brain natriuretic peptide (NT-proBNP) from baseline to 180 days. A hierarchical win-ratio analysis incorporating blindly adjudicated clinical events (cardiovascular deaths and HF hospitalization) and variation in NT-proBNP was also performed. Results: Of 699 included patients, 460 (65.8%) were male, and the mean (SD) age was 61.2 (14.5) years. A total of 352 patients were randomly assigned to the telemonitoring strategy and 347 to standard care. Satisfaction with the telemonitoring strategy was excellent (net promoting score at 180 days, 78.5). HF self-care increased significantly in the telemonitoring group compared with the standard care group (score difference at 30 days, -2.21; 95% CI, -3.67 to -0.74; P = .001; score difference at 180 days, -2.08; 95% CI, -3.59 to -0.57; P = .004). Variation of NT-proBNP was similar in the telemonitoring group compared with the standard care group (telemonitoring: baseline, 2593 pg/mL; 95% CI, 2314-2923; 180 days, 1313 pg/mL; 95% CI, 1117-1543; standard care: baseline, 2396 pg/mL; 95% CI, 2122-2721; 180 days, 1319 pg/mL; 95% CI, 1114-1564; ratio of change, 0.92; 95% CI, 0.77-1.11; P = .39). Hierarchical analysis of the composite outcome demonstrated a similar number of wins in both groups (telemonitoring, 49 883 of 122 144 comparisons [40.8%]; standard care, 48 034 of 122 144 comparisons [39.3%]; win ratio, 1.04; 95% CI, 0.86-1.26). Conclusions and Relevance: An intensive telemonitoring strategy applied in the vulnerable period after an HF admission was feasible, well-accepted, and increased scores of HF self-care but did not translate to reductions in NT-proBNP levels nor improvement in a composite hierarchical clinical outcome. Trial Registration: ClinicalTrials.gov Identifier: NCT04062461.

Prospective analysis of myocardial strain through the evolution of Chagas disease in the hamster animal model.

Speckle tracking echocardiography (STE) enables early diagnosis of myocardial damage by evaluating myocardial strain. We aimed to study sequential changes in structural and ventricular functional parameters during Chagas disease (CD) natural history in an animal model. 37 Syrian hamsters were inoculated intraperitoneally with Trypanosoma cruzi (Chagas) and 20 with saline (Control). Echocardiography was performed before the infection (baseline), at 1 month (acute phase), 4, 6, and 8 months (chronic phase) using Vevo 2100 (Fujifilm Inc.) ultrasound system. Left ventricular end-diastolic diameter, Left ventricular end-systolic diameter (LVESD), Left ventricular ejection fraction (LVEF), Global longitudinal (GLS), circumferential (GCS) and radial (GRS) strain were evaluated. Tricuspid annular plane systolic excursion (TAPSE) was used to assess right ventricular function. At 8 months, animals were euthanized and LV myocardial samples were analyzed for quantitation of inflammation and fibrosis. LVEF decreased over time in Chagas group and a difference from Control was detected at 6 months (p-value of groups#time interaction = 0.005). There was a pronounced decrease in GLS, GCS and TAPSE in Chagas group (p-value of groups#time interaction = 0.003 for GLS, < 0.001 for GCS and < 0.009 for TAPSE vs Control) since the first month. LVESD, LVEF and GLS were significantly correlated to the number of inflammatory cells (r = 0.41, p = 0.046; r = - 0.42, p = 0.042; r = 0.41, p = 0.047) but not to fibrosis. In the Syrian hamster model of CD STE parameters (GLS and GCS) showed an early decrease. Changes in LVEF, LVESD, and GLS were correlated to myocardial inflammation but not to fibrosis.

Design of a multifaceted strategy based on automated text messaging in patients with recent heart failure admission.

AIMS: To evaluate a telemonitoring strategy based on automated text messaging and telephone support after heart failure (HF) hospitalization. METHODS AND RESULTS: The MESSAGE-HF study is a prospective multicentre, randomized, nationwide trial enrolling patients from 30 clinics in all regions of Brazil. HF patients with reduced left ventricular ejection fraction (<40%) and access to mobile phones are eligible after an acute decompensated HF hospitalization. Patients meeting eligibility criteria undergo an initial feasibility text messaging assessment and are randomized to usual care or telemonitoring intervention. All patients receive a HF booklet with basic information and recommendations about self-care. Patients in the intervention group receive four daily short text messages (educational and feedback) during the first 30 days of the protocol to optimize self-care; the feedback text messages from patients could trigger diuretic adjustments or a telephone call from the healthcare team. After 30 days, the frequency of text messages can be adjusted. Patients are followed up after 30, 90, and 180 days, with final status ascertained at 365 days by telephone. Our primary endpoint is the change in N-terminal pro-brain natriuretic peptide (NT-proBNP) levels after 180 days. Secondary endpoints include changes in NT-proBNP after 30 days; health-related quality of life, HF self-care, and knowledge scales after 30 and 180 days; and a composite outcome of HF hospitalization and cardiovascular death, adjudicated by a blinded and independent committee. CONCLUSIONS: The MESSAGE-HF trial is evaluating an educational and self-care promotion strategy involving a simple, intensive, and tailored telemonitoring system. If proven effective, it could be applied to a broader population worldwide.

Feasibility and reference intervals assessed by conventional and speckle-tracking echocardiography in normal hamsters.

OBJECTIVES: This study aimed to determine feasibility, reference intervals, and reproducibility of left ventricular ejection fraction (LVEF) and speckle-tracking echocardiography (STE) in adult Syrian hamsters. BACKGROUND: Syrian hamster is an experimental model for several heart diseases. Echocardiography allows the evaluation of structure and function with bidimensional conventional techniques and STE. However, there is no data regarding reference values for bidimensional LVEF and myocardial strain in hamsters. METHODS: A total of 135 female Syrian hamsters were anesthetized and studied with a small animal dedicated echocardiography system. Echocardiography measurements were obtained from M-mode and B-mode images. Feasibility and 95% reference intervals were obtained for LVEF using three different approaches: LVEF_Teichholz (from M-mode linear measurements), LVEF_BMode (from area-length method), and LVEF_ STE (from strain), and for global longitudinal (GLS), circumferential (GCS), and radial (GRS) endocardial strain. Reproducibility was assessed as intra-class correlation coefficients. RESULTS: Feasibility of LVEF and endocardial strain was high (95% in FEVE_Teichholz, 93% in the LVEF_BMode, 84% in the LVEF_STE, 84% from PSLAX, and 80% from PSSAX). Values of LVEF_Teichholz were significantly higher than values of LVEF_BMode, and LVEF_STE-derived methods (59.0 ± 5.8, 53.8 ± 4.7, 46.3 ± 5.7, p < 0.0001). The 95% reference intervals for GLS, GCS, and GRS were respectively -13.6(-7.5;-20.4)%, -20.5 ± 3.1%, and + 34,7 ± 7.0%. Intra-class correlation coefficients were 0.49 - 0.91 for LVEF measurements, 0.73 - 0.92 for STE, with better results for LVEF_Teichholz and GLS. CONCLUSIONS: Evaluation of LVEF by several methods and STE parameters is feasible in hamsters. Reference intervals for LVEF and STE obtained for this experimental animal model can be applied at future research.

Short-term diuretic withdrawal in stable outpatients with mild heart failure and no fluid retention receiving optimal therapy: a double-blind, multicentre, randomized trial.

AIMS: Although loop diuretics are widely used to treat heart failure (HF), there is scarce contemporary data to guide diuretic adjustments in the outpatient setting. METHODS AND RESULTS: In a prospective, randomized and double-blind protocol, we tested the safety and tolerability of withdrawing low-dose furosemide in stable HF outpatients at 11 HF clinics in Brazil. The trial had two blindly adjudicated co-primary outcomes: (i) symptoms assessment quantified as the area under the curve (AUC) of a dyspnoea score on a visual-analogue scale evaluated at 4 time-points (baseline, Day 15, Day 45, and Day 90) and (ii) the proportion of patients maintained without diuretic reuse during follow-up. We enrolled 188 patients (25% females; 59 ± 13 years old; left ventricular ejection fraction = 32 ± 8%) that were randomized to furosemide withdrawal (n = 95) or maintenance (n = 93). For the first co-primary endpoint, no significant difference in patients' assessment of dyspnoea was observed in the comparison of furosemide withdrawal with continuous administration [median AUC 1875 (interquartile range, IQR 383-3360) and 1541 (IQR 474-3124), respectively; P = 0.94]. For the second co-primary endpoint, 70 patients (75.3%) in the withdrawal group and 77 patients (83.7%) in the maintenance group were free of furosemide reuse during follow-up (odds ratio for additional furosemide use with withdrawal 1.69, 95% confidence interval 0.82-3.49; P = 0.16). Heart failure-related events (hospitalizations, emergency room visits, and deaths) were infrequent and similar between groups (P = 1.0). CONCLUSIONS: Diuretic withdrawal did not result in neither increased self-perception of dyspnoea nor increased need of furosemide reuse. Diuretic discontinuation may deserve consideration in stable outpatients with no signs of fluid retention receiving optimal medical therapy. CLINICALTRIALS.GOV IDENTIFIER: NCT02689180.

Physical training improves myocardial perfusion but not left ventricular function response to exercise in patients with microvascular angina.

BACKGROUND: Patients with primary microvascular angina (PMA) commonly exhibit abnormal left ventricular function (LVF) during exercise, potentially owing to myocardial ischemia. Herein, we investigated in PMA patients the effect of the reduction of myocardial perfusion disorders, by using aerobic physical training, upon LVF response to exercise. METHODS: Overall, 15 patients (mean age, 53.7±8.9 years) with PMA and 15 healthy controls (mean age, 51.0±9.4 years) were studied. All subjects were subjected to baseline resting and exercise ventriculography, myocardial perfusion scintigraphy (MPS), and cardiopulmonary testing. PMA group members then participated in a 4-month physical training program and were reevaluated via the same methods applied at baseline. RESULTS: Baseline left ventricular ejection fraction (LVEF) determinations by ventriculography were similar for both groups (PMA, 67.7±10.2%; controls, 66.5±5.4%; P=0.67). However, a significant rise in LVEF seen in control subjects during exercise (75.3±6.2%; P=0.0001) did not materialize during peak exercise in patients with PMA (67.7±10.2%; P=0.47). Of the 12 patients in the PMA group who completed the training program, 10 showed a significant reduction in reversible perfusion defects during MPS. Nevertheless, LVEF at rest (63.5±8.7%) and at peak exercise (67.3±15.9%) did not differ significantly (P=0.30) in this subset. CONCLUSIONS: In patients with PMA, reduced left ventricular inotropic reserve observed during exercise did not normalize after improving myocardial perfusion through aerobic physical training.

Rational and design of a randomized, double-blind, multicenter trial to evaluate the safety and tolerability of furosemide withdrawal in stable chronic outpatients with heart failure: The ReBIC-1 trial.

AIMS: Furosemide is commonly prescribed for symptom relief in heart failure (HF) patients. Although few data support the continuous use of loop diuretics in apparently euvolemic HF patients with mild symptoms, there is concern about safety of diuretic withdrawal in these patients. The ReBIC-1 trial was designed to evaluate the safety and tolerability of withdrawing furosemide in stable, euvolemic, chronic HF outpatients. This multicenter initiative is part of the Brazilian Research Network in Heart Failure (ReBIC) created to develop clinical studies in HF and composed predominantly by university tertiary care hospitals. METHODS: The ReBIC-1 trial is currently enrolling HF patients in NYHA functional class I-II, left ventricular ejection fraction ≤45%, without a HF-related hospital admission within the last 6 months, receiving a stable dose of furosemide (40 or 80 mg per day) for at least 6 months. Eligible patients will be randomized to maintain or withdraw furosemide in a double-blinded protocol. The trial has two co-primary outcomes: (1) dyspnea assessment using a visual-analogue scale evaluated at 4 time points and (2) the proportion of patients maintained without diuretics during the follow-up period. Total sample size was calculated to be 220 patients. Enrolled patients will be followed up to 90 days after randomization, and diuretic will be restarted if clinical deterioration or signs of congestion are detected. Pre-defined sub-group analysis based on NT-proBNP levels at baseline is planned. PERSPECTIVE: Evidence-based strategies aiming to simplify HF pharmacotherapy are needed in clinical practice. The ReBIC-1 trial will determine the safety of withdrawing furosemide in stable chronic HF patients.

Zika Virus Meningoencephalitis in an Immunocompromised Patient.

The World Health Organization considers the Zika virus (ZIKV) outbreak in the Americas a global public health emergency. The neurologic complications due to ZIKV infection comprise microcephaly, meningoencephalitis, and Guillain-Barré syndrome. We describe a fatal case of an adult patient receiving an immunosuppressive regimen following heart transplant. The patient was admitted with acute neurologic impairment and experienced progressive hemodynamic instability and mental deterioration that finally culminated in death. At autopsy, a pseudotumoral form of ZIKV meningoencephalitis was confirmed. Zika virus infection was documented by reverse trancriptase-polymerase chain reaction, immunohistochemistry, and immunofluorescence and electron microscopy of the brain parenchyma and cerebral spinal fluid. The sequencing of the viral genome in this patient confirmed a Brazilian ZIKV strain. In this case, central nervous system involvement and ZIKV propagation to other organs in a disseminated pattern is quite similar to that observed in other fatal Flaviviridae viral infections.

Short-term and long-term models of doxorubicin-induced cardiomyopathy in rats: A comparison of functional and histopathological changes.

OBJECTIVES: Doxorubicin (DXR), an anthracyclic antineoplastic agent, is one of the most commonly drug utilized to induce dilated cardiomyopathy (DCM) and heart failure (HF), but the well optimized protocol for cardiomyopathy induction leading to development of cardiac systolic dysfunction is unclear. This study aims to critically compare short-term and long-term DXR injection protocols for the induction of DCM in rats. METHODS: Animals were allocated into 3 experimental groups: a ST (short-term DXR injection) group, in which animals received 6 intraperitoneal (i.p.) injections of DXR (2.5mg/kg per dose) over a period of 2 weeks (cumulative dose of 15mg/kg); a LT (long-term DXR injection) group in which animals received weekly i.p. injections of DXR (2mg/kg per dose) over a period of 9 weeks (cumulative dose of 18mg/kg); and a control group in which animals received an appropriate volume of 0.9% saline i.p. All animals were submitted to echocardiography analysis at baseline and after completion treatment. Afterwards, the hearts were collected for conventional light microscopy and collagen quantification. RESULTS: Morphological myocardial analysis of both DXR-treated groups showed an identical pattern of swollen and vacuolated cardiomyocytes and disorganization of myofibrils. There was pronounced interstitial fibrosis in both groups of DXR-treated hearts as compared to controls, as assessed by the interstitial collagen volume fraction. There was no difference in interstitial fibrosis between the ST and LT groups. The echocardiography analysis of the LT group showed structural and functional findings compatible with DCM, including increased left ventricular systolic (5.02±0.96mm) and diastolic (7.68±0.96mm) dimensions and reduction of ejection fraction (69.40±8.51%) as compared to the ST group (4.10±0.89mm, 7.32±0.84, and 79.68±7.23%, respectively) and control group (4.07±0.72mm, 7.17±0.68mm and 80.08±4.71%, respectively), ANOVA p<0.01. CONCLUSIONS: These results indicate that LT injection of DXR is more effective than ST injection in inducing left ventricular dysfunction and structural cardiac changes resembling those found in dilated cardiomyopathy.

Chronic cholinergic stimulation promotes changes in cardiovascular autonomic control in spontaneously hypertensive rats.

Hypertension is often accompanied by autonomic dysfunction, which is detrimental to cardiac regulation. On the other hand, cholinergic stimulation through inhibition of acetylcholinesterase appears to have beneficial effects on cardiac autonomic control. Thus, our objective was to investigate the effects of chronic cholinergic stimulation on hemodynamic and cardiovascular autonomic control parameters in spontaneously hypertensive rats (SHR). For this, 26-week-old SHR (N = 32) and Wistar Kyoto rats (WK; N = 32) were divided into two groups: one treated with vehicle (H2O; N = 16) and the other treated with pyridostigmine bromide (PYR; N = 16) in drinking water (25 mg/kg/day) for 2 weeks. All groups were subjected to recording of arterial pressure (AP) and heart rate (HR), quantification of ejection fraction (EF), evaluation of cardiac tonic autonomic balance by means of double autonomic blockade with methylatropine and propranolol, analysis of systolic AP (SAP) and HR variability (HRV), and evaluation of baroreflex sensitivity (BRS). AP, HR, and EF were reduced in the SHR-PYR group compared with the SHR-H2O group. Evaluation of autonomic parameters revealed an increase in vagal tone participation in cardiac tonic autonomic balance and reduced SAP variability; however, no changes were observed in HRV or BRS. These results suggest that chronic cholinergic stimulation with pyridostigmine bromide promotes reduction in the hemodynamic parameters AP, HR, and EF. Additionally, tonic autonomic balance was improved and a reduction in LF oscillations of SAP variability was observed that could not be attributed to BRS, as the latter did not change. Further studies should be conducted to identify the mechanisms involved in the observed responses.

Calpain-mediated dystrophin disruption may be a potential structural culprit behind chronic doxorubicin-induced cardiomyopathy.

The critical importance of dystrophin to cardiomyocyte contraction and sarcolemmal and myofibers integrity, led us to test the hypothesis that dystrophin reduction/loss could be involved in the pathogenesis of doxorubicin-induced cardiomyopathy, in order to determine a possible specific structural culprit behind heart failure. Rats received total cumulative doses of doxorubicin during 2 weeks: 3.75, 7.5, and 15 mg/kg. Controls rats received saline. Fourteen days after the last injection, hearts were collected for light and electron microscopy, immunofluorescence and western blot. The cardiac function was evaluated 7 and 14 days after drug or saline. Additionally, dantrolene (5 mg/kg), a calcium-blocking agent that binds to cardiac ryanodine receptors, was administered to controls and doxorubicin-treated rats (15 mg/kg). This study offers novel and mechanistic data to clarify molecular events that occur in the myocardium in doxorubicin-induced chronic cardiomyopathy. Doxorubicin led to a marked reduction/loss in dystrophin membrane localization in cardiomyocytes and left ventricular dysfunction, which might constitute, in association with sarcomeric actin/myosin proteins disruption, the structural basis of doxorubicin-induced cardiac depression. Moreover, increased sarcolemmal permeability suggests functional impairment of the dystrophin-glycoprotein complex in cardiac myofibers and/or oxidative damage. Increased expression of calpain, a calcium-dependent protease, was markedly increased in cardiomyocytes of doxorubicin-treated rats. Dantrolene improved survival rate and preserved myocardial dystrophin, calpain levels and cardiac function, which supports the opinion that calpain mediates dystrophin loss and myofibrils degradation in doxorubicin-treated rats. Studies are needed to further elucidate this mechanism, mainly regarding specific calpain inhibitors, which may provide new interventional pathways to prevent doxorubicin-induced cardiomyopathy.

Discinergia ventricular esquerda reversível identificada por potenciação pós-extrassistólica em miocardiopatia chagásica crônica não é causada por hibernação miocárdica / Reversible dysynergy identified by post-extrasystolic potentiation in chronic chagas cardiomyopathy is not caused by myocardial hibernation

A alteração regional da mobilidade segmentar do ventrículo esquerdo é marcador precoce de miocardiopatia chagásica crônica. Demonstramos recentemente que a discinergia em algumas regiões ventriculares pode ser revertida pela potenciação pós-extrassistólica. Apesar de angiografia coronária normal, pacientes com miocardiopatia chagásica apresentam falhas de perfusão, corroborando a hipótese de que a hibernação miocárdica pode ser responsável pelas anormalidades de mobilidade segmentar revertidas durante a potenciação pós-extrassistólica. Método: Vinte e dois pacientes consecutivos portadores de miocardiopatia chagásica foram submetidos a angiografia coronária, ventriculografia e cintilografia miocárdica com tálio-201 com o protocolo estresse-redistribuição-reinjeção para avaliação da perfusão dos segmentos do ventrículo esquerdo...

Background: Regional left ventricular segmental wall motion impairment is an early marker of chronic Chagas cardiomyopathy. We have recently shown that dysynergy may be reversed in some ventricular regions by post-extrasystolic potentiation. Despite normal epicardial coronary arteries, patients with Chagas cardiomyopathy have perfusion defects, raising the possibility that myocardial hibernation could be responsible for the wall motion abnormalities reversed during post-extrasystolic potentiation. Methods: Twentytwo consecutive patients with chronic Chagas cardiomyopathy underwent coronary angiography, left ventricular contrast angiography and stress-redistribution-reinjection thallium-201 myocardial scintigraphy for the assessment of the perfusion status in left ventricular segments showing the presence of post-extrasystolic potentiation...

Changes in myocardial perfusion correlate with deterioration of left ventricular systolic function in chronic Chagas' cardiomyopathy.

OBJECTIVES: This study aimed at analyzing the association between myocardial perfusion changes and the progression of left ventricular systolic dysfunction in patients with chronic Chagas' cardiomyopathy (CCC). BACKGROUND: Pathological and experimental studies have suggested that coronary microvascular derangement, and consequent myocardial perfusion disturbance, may cause myocardial damage in CCC. METHODS: Patients with CCC (n = 36, ages 57 +/- 10 years, 17 males), previously having undergone myocardial perfusion single-positron emission computed tomography and 2-dimensional echocardiography, prospectively underwent a new evaluation after an interval of 5.6 +/- 1.5 years. Stress and rest myocardial perfusion defects were quantified using polar maps and normal database comparison. RESULTS: Between the first and final evaluations, a significant reduction of left ventricular ejection fraction was observed (55 +/- 11% and 50 +/- 13%, respectively; p = 0.0001), as well as an increase in the area of the perfusion defect at rest (18.8 +/- 14.1% and 26.5 +/- 19.1%, respectively; p = 0.0075). The individual increase in the perfusion defect area at rest was significantly correlated with the reduction in left ventricular ejection fraction (R = 0.4211, p = 0.0105). Twenty patients with normal coronary arteries (56%) showed reversible perfusion defects involving 10.2 +/- 9.7% of the left ventricle. A significant topographic correlation was found between reversible defects and the appearance of new rest perfusion defects at the final evaluation. Of the 47 segments presenting reversible perfusion defects in the initial study, 32 (68%) progressed to perfusion defects at rest, and of the 469 segments not showing reversibility in the initial study, only 41 (8.7%) had the same progression (p < 0.0001, Fisher exact test). CONCLUSIONS: In CCC patients, the progression of left ventricular systolic dysfunction was associated with both the presence of reversible perfusion defects and the increase in perfusion defects at rest. These results support the notion that myocardial perfusion disturbances participate in the pathogenesis of myocardial injury in CCC.

Persistência de distúrbios perfusionais miocárdicos após intervenção coronária percutânea com êxito: dependência de fatores microcirculatórios / Myocardial perfusion disturbances persisting after successful percutaneous coronary angioplasty: relationship to microcirculatory derangements

Introdução: A persistência transitória de defeitos perfusionais imediatamente após intervenção coronária percutânea bem sucedida para correção de estenoses coronárias é bem documentada. Método: Para testar a hipótese de que tais anormalidades perfusionais sejam associadas a distúrbios microcirculatórios causados por microembolização coronária, comparou-se a intensidade e extensão desses defeitos perfusionais detectados com cintilografia miocárdica em grupos randomicamente constituídos de pacientes tratados com angioplastia coronária por balão (AB) ou submetidos a aterectomia rotacional complementada por balão (AR + B). As características clínicas e angiográficas foram comparáveis nos dois grupos, assim como o sucesso do procedimento de angioplastia coronária. Resultados: Antes da intervenção coronária percutânea, o índice de defeito miocárdico, englobando a extensão e a gravidade da hipoperfusão, foi comparável nos dois grupos, na condição de estresse (AB = 7,72±1,91 vs AR + B = 8,61±3,38) e de repouso (AB = 3,11±1,22 vs AR + B = 2,40±1,63). Após o procedimento, o índice de defeito perfusional decresceu em ambos os grupos durante o estresse, mas com significância estatística apenas no grupo AB = 3,96±1,40 vs AR + B = 3,71 ±1,89. O contraste entre os dois grupos se acentuou na condição de repouso após a intervenção coronária: o índice de defeito decresceu de forma marginalmente significante no grupo AB para 1,46±0,66 e aumentou, embora sem significância estatística, no grupo AR + B, para 3,47±1,92. Conclusão: Esses resultados são compatíveis com o conceito de que a persistência transitória de defeitos perfusionais após angioplastia coronária bem sucedida seja dependente de distúrbios microcirculatórios associados à microembolização durante o procedimento.

Introduction: The transitory persistence of perfusion defects immediately after successful percutaneous coronary interventions to correct coronary stenosis is well known. Methods: To test the hypothesis that such perfusion abnormalities are associated with microcirculatory disorders caused by coronary microembolization we compared the intensity and extent of these perfusion defects detected using myocardial scintigraphy in groups of patients randomly assigned to coronary balloon angioplasty (BA) or to rotational atherectomy plus balloon angioplasty (RA + B). The clinical and angiography characteristics were comparable in both groups, as well as the successof the coronary angioplasty procedure. Results: Before the percutaneous coronary intervention the myocardium defect index, related to the extent and severity of hypoperfusion, was comparable for the two groups, both under stress (AB =7.72±1.91 vs. RA + B = 8.61±3.38) and at rest (AB = 3.11±1.22vs. RA + B = 2.40±1.63). After the procedure, the perfusion defect index decreased for both groups during stress, but with statistical significance only in the AB Group = 3.96±1.40 vs. RA + B = 3.71±1.89. The difference between the two groups was greater at rest after the coronary intervention procedure: the defect index decreased with marginal significance for the AB Group to 1.46±0.66 and increased, though without statistical significance, for the RA + B Group to 3.47±1.92. Conclusion: These results are compatible with the notion that transitory persistence of perfusion defects after successful coronary angioplasty are dependent on microcirculatory disorders associated to microembolization during the procedure