Neuromuscular electrical stimulation but not photobiomodulation therapy improves cardiovascular parameters of rats with heart failure.

The aim of the present study was to analyze the effect of neuromuscular electrical stimulation (NMES) and photobiomodulation (PBMT) on the cardiovascular parameters, hemodynamic function, arterial baroreflex sensitivity (BRS), and autonomic balance (ANS) of rats with heart failure (HF). Male Wistar rats (220-290 g) were organized into five groups: Sham (n = 6), Control-HF (n = 5), NMES-HF (n = 6), PBMT-HF (n = 6), and NMES + PBMT-HF (n = 6). Myocardial infarction (MI) was induced by left coronary artery ligation. Animals were subjected to an eight-week NMES and PBMT protocol. Statistical analysis included the General Linear Model (GLM) followed by a Bonferroni post-hoc test. Rats of the NMES-HF group showed a higher MI area than the Control-HF (P = 0.003), PBMT-HF (P = 0.002), and NMES + PBMT-HF (P = 0.012) groups. NMES-HF and NMES + PBMT-HF showed higher pulmonary congestion (P = 0.004 and P = 0.02) and lower systolic pressure (P = 0.019 and P = 0.002) than the Sham group. NMES + PBMT-HF showed lower mean arterial pressure (P = 0.02) than the Sham group. Control-HF showed a higher heart rate than the NMES-HF and NMES + PBMT-HF (P = 0.017 and P = 0.013) groups. There was no difference in the BRS and ANS variables between groups. In conclusion, eight-week NMES isolated or associated with PBMT protocol reduced basal heart rate, systolic and mean arterial pressure, without influence on baroreflex sensibility and autonomic control, and no effect of PBMT was seen in rats with HF.

Pterostilbene improves cardiac function in a rat model of right heart failure through modulation of calcium handling proteins and oxidative stress.

This study explored the effect of pterostilbene (PTS) complexed with hydroxypropyl-ß-cyclodextrin (HPßCD) on right heart function, glutathione and glutaredoxin systems, and the expression of redox-sensitive proteins involved with regulation calcium levels in the experimental model of pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). After 7 days of PAH induction, rats received daily doses of the PTS:HPßCD complex (corresponding to 25, 50, or 100 mg·kg-1 of PTS) or vehicle (control group, CTR0) (an aqueous solution containing HPßCD; CTR0 and MCT0 (MCT group that did not receive PTS treatment)) via oral administration for 2 weeks. The results showed that the PTS:HPßCD complex increased the content of reduced glutathione and the activity of glutathione-S-transferase and glutaredoxin in the right ventricle (RV) of MCT-treated rats in a dose-dependent manner. Additionally, at higher doses, it also prevented the reduction of stroke volume and cardiac output, prevented myocardial performance index (MPI) increase, reduced lipoperoxidation, reduced total phospholamban, and increased the expression of sarcoplasmic reticulum calcium ATPase in the RV of MCT-treated rats. These results demonstrate that the PTS:HPßCD complex has a dose-dependent antioxidant mechanism that results in improved cardiac function in experimental right heart failure. Our results open a field of possibilities to PTS administration as new therapeutic approach to conventional therapy for right ventricular dysfunction. Novelty Pterostilbene complexed with hydroxypropyl-ß-cyclodextrin could be a new therapeutic approach. Pterostilbene complexed with hydroxypropyl-ß-cyclodextrin reestablishes redox homeostasis through glutathione metabolism modulation, leading to an improved MPI in pulmonary arterial hypertension-provoked right heart failure.

Correlation of 6-min walk test with left ventricular function and quality of life in heart failure due to Chagas disease.

OBJECTIVES: To evaluate the correlation of the total distance walked during the six-minute walk test (6MWT) with left ventricular function and quality of life in patients with Chagas Disease (ChD) complicated by heart failure. METHODS: This is a cross-sectional study of adult patients with ChD and heart failure diagnosed based on Framingham criteria. 6MWT was performed following international guidelines. New York Heart Association functional class, brain natriuretic peptide (BNP) serum levels, echocardiographic parameters and quality of life (SF-36 and MLHFQ questionnaires) were determined and their correlation with the distance covered at the 6MWT was tested. RESULTS: Forty adult patients (19 male; 60 ± 12 years old) with ChD and heart failure were included in this study. The mean left ventricular ejection fraction was 35 ± 12%. Only two patients (5%) ceased walking before 6 min had elapsed. There were no cardiac events during the test. The average distance covered was 337 ± 105 metres. The distance covered presented a negative correlation with BNP (r = -0.37; P = 0.02), MLHFQ quality-of-life score (r = -0.54; P = 0.002), pulmonary artery systolic pressure (r = -0.42; P = 0.02) and the degree of diastolic dysfunction (r = -0.36; P = 0.03) and mitral regurgitation (r = -0.53; P = 0.0006) and positive correlation with several domains of the SF-36 questionnaire. CONCLUSIONS: The distance walked during the 6MWT correlates with BNP, quality of life and parameters of left ventricular diastolic function in ChD patients with heart failure. We propose this test to be adopted in endemic areas with limited resources to aid in the identification of patients who need referral for tertiary centres for further evaluation and treatment.

Combined analysis of cross-reacting antibodies anti-ß1AR and anti-B13 in advanced stages of Chagas heart disease.

OBJECTIVE: Autoantibodies cross-reacting with the ß1 adrenergic receptor (anti-ß1AR and anti-p2ß) and cardiac myosin antigens (anti-B13) have been related to the pathogenesis of chronic Chagas heart disease (CCHD). Studies exploring their levels in different stages are scarce. We aimed to evaluate the relationship of these autoantibodies with the clinical profile of chronic patients, especially regarding their classificatory accuracy in severe presentation with heart failure. METHODS AND RESULTS: We conducted a cross-sectional study of 155 T. cruzi-seropositive patients and 26 age- and gender-matched healthy controls. They were categorised in three stages of CCHD. Serum antibodies were measured by specific immunoassays. Symptomatic individuals showed increased levels of anti-ß1AR and anti-B13, while anti-p2ß antibodies were similar between groups. A composite logistic regression model including anti-B13, anti-ß1AR antibody levels and age was able to predict systolic heart failure yielding an area under the curve of 83% (sensitivity of 67% and specificity of 89%). CONCLUSIONS: In our study, anti-ß1AR and anti-B13 antibodies were higher in individuals with chronic Chagas heart disease stage III, mainly in those with dilated cardiomyopathy associated with systolic heart failure. Logistic regression analysis showed that both antibodies were good predictors of severe CCHD. As well as being involved in disease progression, anti-ß1AR and anti-B13 antibodies may be used as a serum marker of poor prognosis in terms of heart compromise.

Exercise training attenuates the pressor response evoked by peripheral chemoreflex in rats with heart failure.

The effects of exercise training (ExT) on the pressor response elicited by potassium cyanide (KCN) in the rat model of ischemia-induced heart failure (HF) are unknown. We evaluated the effects of ExT on chemoreflex sensitivity and its interaction with baroreflex in rats with HF. Wistar rats were divided into four groups: trained HF (Tr-HF), sedentary HF (Sed-HF), trained sham (Tr-Sham), and sedentary sham (Sed-Sham). Trained animals underwent to a treadmill running protocol for 8 weeks (60 m/day, 5 days/week, 16 m/min). After ExT, arterial pressure (AP), baroreflex sensitivity (BRS), peripheral chemoreflex (KCN: 100 µg/kg body mass), and cardiac function were evaluated. The results demonstrate that ExT induces an improvement in BRS and attenuates the pressor response to KCN relative to the Sed-HF group (P < 0.05). The improvement in BRS was associated with a reduction in the pressor response following ExT in HF rats (P < 0.05). Moreover, ExT induced a reduction in left ventricular end-diastolic pressure and pulmonary congestion compared with the Sed-HF group (P < 0.05). The pressor response to KCN in the hypotensive state is decreased in sedentary HF rats. These results suggest that ExT improves cardiac function and BRS and attenuates the pressor response evoked by KCN in HF rats.

Digitoxin improves cardiovascular autonomic control in rats with heart failure.

The effects of chronic treatment with digitoxin on arterial baroreceptor sensitivity for heart rate (HR) and renal sympathetic nerve activity (rSNA) control, cardiopulmonary reflex, and autonomic HR control in an animal model of heart failure (HF) were evaluated. Wistar rats were treated with digitoxin, which was administered in their daily feed (1 mg/kg per day) for 60 days. The following 3 experimental groups were evaluated: sham, HF, and HF treated with digitoxin (HF + DIG). We observed an increase in rSNA in the HF group (190 ± 29 pps, n = 5) compared with the sham group (98 ± 14 pps, n = 5). Digitoxin treatment prevented an increase in rSNA (98 ± 14 pps, n = 7). Therefore, arterial baroreceptor sensitivity was decreased in the HF group (-1.24 ± 0.07 bpm/mm Hg, n = 8) compared with the sham group (-2.27 ± 0.23 bpm/mm Hg, n = 6). Digitoxin did not alter arterial baroreceptor sensitivity in the HF + DIG group. Finally, the HF group showed an increased low frequency band (LFb: 23 ± 5 ms(2), n = 8) and a decreased high frequency band (HFb: 77 ± 5 ms(2), n = 8) compared with the sham group (LFb: 14 ± 3 ms(2); HFb: 86 ± 3 ms(2), n = 9); the HF+DIG group exhibited normalized parameters (LFb: 15 ± 3 ms(2); HFb: 85 ± 3 ms(2), n = 9). In conclusion, the benefits of decreasing rSNA are not directly related to improvements in peripheral cardiovascular reflexes; such occurrences are due in part to changes in the central nuclei of the brain responsible for autonomic cardiovascular control.