Post-exercise heart rate recovery and its speed are associated with cardiac autonomic responsiveness following orthostatic stress test in men.

Objective: The present study sought to expand upon prior investigations of the relationship between the post-exercise heart rate recovery (HRR) and the cardiac autonomic responsiveness after orthostatic stress test.Method: HRR at the 1st, 3rd, and 5th min after maximal exercise test were correlated with relative change (Δ%) of time-domain (CV, pNN50, and rMSSD) and frequency-domain (TP, LF, HF, and LF/HF ratio) indices of heart rate variability (HRV) after active orthostatic test in 46 healthy men. Statistical analysis employed non-parametric tests with a p-value set at 5%.Results: HRR at 1st min correlated with Δ%pNN50 (rs:0.36 - p = .02). In the 3rd and 5th min, these measures correlated with Δ%pNN50, Δ%rMSSD, Δ%CV, Δ%TP, and Δ%HF indices (rs:0.33, 0.59 - p ≤ .05). Coefficient of HRR at the 1st min correlated with Δ%pNN50, Δ%rMSSD, and Δ%HF (rs:0.28, 0.45 - p ≤ .05). The 3rd and 5th min showed correlation with Δ%pNN50, Δ%rMSSD, Δ%HF, Δ%CV, and Δ%TP (rs:0.37, 0.64 - p ≤ .05). No correlation was found with indices combined sympathetic-parasympathetic modulation and HRR. After the sample was divided into high and low parasympathetic responsiveness subgroups after the orthostatic test, faster HRR was associated with the degree of parasympathetic responsiveness (reduction) following postural change (p ≤ .05).Conclusion: HRR throughout the 1st to 5th min is positively correlated with parasympathetic responsiveness and overall cardiac autonomic modulation of HRV after the orthostatic stress test, and faster HRR is positively correlated with the relative degree of parasympathetic responsiveness after the active postural change at rest in healthy men.

Firefighters' basal cardiac autonomic function and its associations with cardiorespiratory fitness.

BACKGROUND: Firefighters' activities require constant adjustments of the cardiovascular system with cardiac autonomic function (CAF) playing an important role. Despite the crucial role of CAF in regulating stress response, little is known about firefighters' CAF. OBJECTIVE: We aimed to characterize the resting on-duty and off-duty CAF of male firefighters, in association with cardiorespiratory fitness (CRF). METHODS: We evaluated 38 firefighters in an on-duty rest condition and 26 firefighters in an off-duty laboratory-controlled condition. CAF was addressed by means of heart rate variability (HRV). We compared HRV measurements between CRF categories (<12METs vs ≥12METs). Wilcoxon, Mann-Whitney texts and Spearman correlation were used and General Linear Model was applied for age and BMI adjustments. RESULTS: Firefighters' resting CAF is characterized by a predominant sympathetic modulation and a large inter-individual dispersion in all HRV indices, in both groups. We found a positive correlation between a higher CRF, the overall CAF and the higher parasympathetic activity (p <  0,03). Firefighters with CRF ≥12 METs showed a higher parasympathetic modulation. CONCLUSIONS: Firefighters' resting CAF is characterized by a predominant sympathetic modulation and a large inter-individual dispersion in all HRV indices, in both groups. Our results support mandatory physical training focused in improving firefighters' CAF as a cardiopretective effect.

Resting Bradycardia, Enhanced Postexercise Heart Rate Recovery and Cardiorespiratory Fitness in Recreational Ballroom Dancers.

PURPOSE: In a cross-sectional study design, we evaluated the resting heart rate (HRbaseline) and exercise and postexercise stress test-related chronotropic responses in male practitioners of recreational ballroom dancing (BD; n = 25, Mage = 26.6 ± 6.1 years) compared to a control group of insufficiently active nondancers (CG; n = 25, Mage = 25.9 ± 4.5 years). METHOD: All participants underwent a submaximal exercise test. At 85% of the maximal predicted HR, the recovery protocol was started, and heart rate recovery (HRR) was recorded during 1-min intervals for 5 min. RESULTS: Compared with CG, BD showed lower HRbaseline (70 beats per minute [bpm] vs. 62 bpm, respectively, U = 143, p < .05, ES = .46), lower preexercise HR (94 bpm vs. 86 bpm, U = 157, p < .05, ES = .42), longer exercise test duration (346 s vs. 420 s, U = 95.5, p < .05, ES = .59), and higher HRR for 5 min postexercise (U = 1.29-1.89, p < .05, ES = .33-.50) as follows: 1st min (32 bpm vs. 40 bpm), 2nd min (45 bpm vs. 53 bpm), 3rd min (51 bpm vs. 58 bpm), 4th min (55 bpm vs. 59 bpm), and 5th min (59 bpm vs. 63 bpm). The coefficient of HRR from the 1st min to the 5th min postexercise was similar in both groups (U = 229-311, p > .05, ES = < .10-.22). CONCLUSION: Heightened cardiovascular functional status characterized by favorable enhanced chronotropic dynamics appears to occur in practitioners of recreational ballroom dancing, which suggests that this modality of exercise may result in health benefits.

Agreement between BMI and body fat obesity definitions in a physically active population.

OBJECTIVES: Body mass index (BMI) is a widely used proxy of body composition (BC). Concerns exist regarding possible BMI misclassification among active populations. We compared the prevalence of obesity as categorized by BMI or by skinfold estimates of body fat percentage (BF%) in a physically active population. SUBJECTS AND METHODS: 3,822 military firefighters underwent a physical fitness evaluation including cardiorespiratory fitness (CRF) by the 12 min-Cooper test, abdominal strength by sit-up test (SUT) and body composition (BC) by BF% (as the reference), as well as BMI. Obesity was defined by BF% > 25% and BMI ≥ 30 kg/m2. Agreement was evaluated by sensitivity and specificity of BMI, positive and negative predictive values (PPV/NPV), positive and negative likelihood (LR+/LR-), receiver operating characteristic (ROC) curves and also across age, CRF and SUT subgroups. RESULTS: The prevalence of obesity estimated by BMI (13.3%) was similar to BF% (15.9%). Overall agreement was high (85.8%) and varied in different subgroups (75.3-94.5%). BMI underestimated the prevalence of obesity in all categories with high specificity (≥ 81.2%) and low sensitivity (≤ 67.0). All indices were affected by CRF, age and SUT, with better sensitivity, NPV and LR- in the less fit and older groups; and higher specificity, PPV and LR+ among the fittest and youngest groups. ROC curves showed high area under the curve (≥ 0.77) except for subjects with CRF ≥ 14 METs (= 0.46). CONCLUSION: Both measures yielded similar obesity prevalences, with high agreement. BMI did not overestimate obesity prevalence. BMI ≥ 30 was highly specific to exclude obesity. Because of systematic under estimation, a lower BMI cut-off point might be considered in this population.

Post-exercise heart-rate recovery correlates to resting heart-rate variability in healthy men.

JUSTIFICATIVE: The relationship between post-exercise heart-rate recovery (HRR) and resting cardiac autonomic modulation is an incompletely explored issue. OBJECTIVE: To correlate HRR with resting supine and orthostatic autonomic status. METHOD: HRR at the 1st, 3th, and 5th min following maximal treadmill exercise were correlated with 5-min time-domain (CV, pNN50 and rMSSD) and frequency-domain (TP, LF, HF, LFn, HFn, and LF/HF ratio) indices of heart-rate variability (HRV) in both supine and standing positions in 31 healthy physically active non-athletes men. Statistical analysis employed non-parametric tests with two-tailed p value set at 5 %. RESULTS: Absolute HRR and Δ %HRR at each post-exercise time did not correlated with HRV in supine position, as well as at 1st min in standing position. At the 3rd min and 5th min, these measures negatively correlated with pNN50, rMSSD, TP, and HF indices, and only in the 5th min, they showed negative correlation with HFn and positive correlation with LF, LFn, and LF/HF ratio in the standing position. Coefficient of HRR (CHRR) at the 1st min negatively correlated with pNN50 and rMSSD and at 3rd and 5th min showed positive correlation with LFn and LF/HF ratio in supine position. With HRV indices in standing position CHRR from the 1st to 5th min showed the same respective negative and positive correlations as the other measures. CONCLUSION: HRR from the 1st to 5th min post-exercise negatively correlated with parasympathetic modulation in resting orthostatic, but showed no correlation in supine position. At the 3rd and 5th min, a positive correlation with combined sympathetic-parasympathetic modulation in both positions was observed.

Risk factors for prolonged hospital stay after isolated coronary artery bypass grafting.

INTRODUCTION: Characteristics of the patient and the coronary artery bypass grafting may predispose individuals to prolonged hospitalization, increasing costs and morbidity and mortality. OBJECTIVE: The objective of this study was to evaluate individual and perioperative risk factors of prolonged hospitalization in intensive care units and wards. METHODS: We conducted a case-control study of 104 patients undergoing isolated coronary artery bypass grafting with cardiopulmonary bypass. Patients hospitalized >3 days in the intensive care unit or >7 days in the ward were considered for the study. The association between variables was estimated by the chi-square test, odds ratio and logistic regression; P <0.05 was considered statistically significant. RESULTS: Hospital stay >3 days in the intensive care unit occurred for 22.1% of patients and >7 days in the ward for 27.9%. Among preoperative factors, diabetes (OR=3.17) and smoking (OR=4.07) were predictors of prolonged intensive care unit stay. Combining the pre-, intra-and postoperative variables, only mechanical ventilation for more than 24 hours (OR=6.10) was predictive of intensive care unit outcome. For the ward outcome, the preoperative predictor was left ventricular ejection fraction <50% (OR=3.04). Combining pre- and intraoperative factors, diabetes (OR=2.81), and including postoperative factors, presence of infection (OR=4.54) were predictors of prolonged hospitalization in the ward. CONCLUSION: Diabetes and smoking were predictors of intensive care unit outcome, and ejection fraction <50% of ward outcome. For the set of perioperative factors, prolonged hospitalization after isolated coronary artery bypass grafting was associated with mechanical ventilation >24 hours for the intensive care unit and presence of infection for the ward.

Insights into the clinical and functional significance of cardiac autonomic dysfunction in Chagas disease.

INTRODUCTION: Exclusive or associated lesions in various structures of the autonomic nervous system occur in the chronic forms of Chagas disease. In the indeterminate form, the lesions are absent or mild, whereas in the exclusive or combined heart and digestive disease forms, they are often more pronounced. Depending on their severity these lesions can result mainly in cardiac parasympathetic dysfunction but also in sympathetic dysfunction of variable degrees. Despite the key autonomic effect on cardiovascular functioning, the pathophysiological and clinical significance of the cardiac autonomic dysfunction in Chagas disease remains unknown. METHODS: Review of data on the cardiac autonomic dysfunction in Chagas disease and their potential consequences, and considerations supporting the possible relationship between this disturbance and general or cardiovascular clinical and functional adverse outcomes. RESULTS: We hypothesise that possible consequences that cardiac dysautonomia might variably occasion or predispose in Chagas disease include: transient or sustained arrhythmias, sudden cardiac death, adverse overall and cardiovascular prognosis with enhanced morbidity and mortality, an inability of the cardiovascular system to adjust to functional demands and/or respond to internal or external stimuli by adjusting heart rate and other hemodynamic variables, and immunomodulatory and cognitive disturbances. CONCLUSIONS: Impaired cardiac autonomic modulation in Chagas disease might not be a mere epiphenomenon without significance. Indirect evidences point for a likely important role of this alteration as a primary predisposing or triggering cause or mediator favouring the development of subtle or evident secondary cardiovascular functional disturbances and clinical consequences, and influencing adverse outcomes.

Cardiac autonomic and ventricular mechanical functions in asymptomatic chronic chagasic cardiomyopathy.

BACKGROUND: The association of variably altered cardiac autonomic and ventricular systolic and diastolic functions is still controversial and little explored in chronic Chagas' disease. OBJECTIVE: To evaluate the extent to which cardiac autonomic and mechanical ventricular functions are altered and whether they are associated in asymptomatic chagasic cardiomyopathy. METHODS: A total of 13 patients with asymptomatic chagasic cardiomyopathy and 15 normal subjects (control group) were evaluated and the autonomic modulation of heart rate variability for five minutes, in the temporal and spectral domains, in the supine and orthostatic positions, as well as ventricular function based on morphological-functional variables obtained by Doppler echocardiography were correlated. Statistical analysis used the Mann-Whitney test and Spearman's correlation. RESULTS: In both positions, the temporal index (p = 0.0004 to 0.01) and total (p = 0.0007-0.005) and absolute spectral areas, of low and high frequencies (p = 0.0001 to 0.002), were lower in the chagasic group. The vagal-sympathetic balance was similar in both positions (p = 0.43 to 0.89). The echocardiographic variables did not differ between groups (p = 0.13 to 0.82), except the left ventricular end-systolic diameter, which was larger (p = 0.04) and correlated directly with reduced rates of global (p = 0.01 to 0.04) and parasympathetic (p = 0.002 to 0.01) autonomic modulation in patients with Chagas disease in the orthostatic position. CONCLUSION: The sympathetic and parasympathetic depressions with preserved balance were associated with only one ventricular dysfunction indicator. This suggests that cardiac autonomic dysfunction may precede and be independently more severe than ventricular dysfunction, with no causal association between both disorders in chronic chagasic cardiomyopathy.

Cardiac autonomic modulation and cognitive status in Alzheimer's disease.

INTRODUCTION: Although nervous structures affected in Alzheimer's disease are also implicated in autonomic nervous system function, the relationship between autonomic and cognitive functions was not still investigated. METHODS: The cardiac autonomic modulation of 5-min heart interval variability evaluated by time- and frequency-domain indexes, in supine and standing positions, of 22 Alzheimer's disease patients (90.9% women) aged 79.6 +/- 1.4 years (mean +/- SE) was correlated with mild to severe cognitive impairment scored by the CAMCOG and MMSE subset tests, by the Spearman's correlation analysis. RESULTS: Age and level of education were not correlated with the heart interval variability indexes and the cognitive scores. Significantly positive (r (s) = 0.43-0.47, P = 0.03-0.04) or trend (r (s) = 0.36-0.40, P = 0.06-0.10) correlation was observed in both positions between the cognitive performance and pNN50%, rMSSD and absolute and normalised high-frequency power, considered to express parasympathetic modulation. Negative trend correlation (r (s) = -0.35 to -0.39, P = 0.07-0.10) was observed between absolute sympathetic modulation (low-frequency power and low-to-high frequency power ratio) in supine posture. CONCLUSION: The cognitive status and the cardiac sympathovagal modulation appear to be correlated and hypothetically may influence one another in mild to severe Alzheimer's disease. Individuals with more severe cognitive deficiency showed suggestive lower cardiac parasympathetic modulation and trend for higher cardiac sympathetic modulation.

Distinctive impaired cardiac autonomic modulation of heart rate variability in chronic Chagas' indeterminate and heart diseases.

INTRODUCTION: Cardiac autonomic dysfunction occurs in Chagas' indeterminate and heart disease, but comparison of this disturbance between both forms was not yet performed. METHODS: Time- and frequency-domain 5-minute heart rate variability in supine and standing positions were evaluated in 17 subjects with Chagas' disease with the indeterminate form, 13 with heart disease and 15 controls. Trend of variability indices across the groups was also tested. RESULTS: In the supine position, reduced time-domain and absolute frequency-domain indices reflecting overall autonomic modulation were observed in both Chagas' disease groups. In the standing position, the coefficient of variation and those frequency-domain indices were also reduced, and the other time-domain indices were reduced only in the cardiac group. Heart rate variability indices hypothesized to reflect relative sympathetic and parasympathetic activity showed no alteration. A significant graded reduction was observed in the altered indices in both postures, from the control to the Chagas' indeterminate and heart disease groups. CONCLUSION: Cardiac autonomic dysfunction, with preserved putative measures of sympathetic and parasympathetic modulation in relative terms, was less severe or absent in the indeterminate and pronounced in cardiac form of Chagas' disease.

Cardiac sympathovagal modulation evaluated by short-term heart interval variability is subtly impaired in Alzheimer's disease.

AIM: Alzheimer's disease affects several nervous structures involved with the autonomic nervous system. Therefore, the still scarce evaluation of the cardiac autonomic function in this disease is of great functional, clinical, prognostic and therapeutic relevance. METHODS: Time- and frequency-domain variability of 5-min R-R interval series in supine and standing positions was comparatively evaluated in 22 Alzheimer's disease subjects, aged 60-87 years (mean +/- standard error of the mean, 79.6 +/- 1.4) with variable cognitive impairment, and 24 healthy individuals, aged 60-91 years (68.6 +/- 1.6). The Student's t-test was used to compare the variability indices between the groups and logistic regression excluded the effects on these indices in the Alzheimer's group of confounding variables different from the control group (age, physical activity and caffeinated intake), at a significance level of P

Teaching cardiac autonomic function dynamics employing the Valsalva (Valsalva-Weber) maneuver.

In this report, a brief history of the Valsalva (Valsalva-Weber) maneuver is outlined, followed by an explanation on the use of this approach for the evaluation of cardiac autonomic function based on underlying heart rate changes. The most important methodological and interpretative aspects of the Valsalva-Weber maneuver are critically updated, and some guidelines are established for simple application of the maneuver in a teaching or research laboratory setting. These include the hemodynamic and cardiac autonomic mechanisms involved, technical aspects such as the intensity and duration of the expiratory straining, frequency of maneuver sessions, training and posture of the individuals tested, different time- and grade change-dependent indexes of heart interval variation, and clinical application of the maneuver.

Cardiac autonomic modulation evaluated by heart interval variability is unaltered but subtly widespread in the indeterminate Chagas' disease.

BACKGROUND: Cardiac autonomic function in the indeterminate chronic form of Chagas' disease deserves better clearing-up and understanding, since the existing findings are scarce and controversial. This work analyzed the short-term heart interval variability in order to verify the cardiac autonomic modulation in indeterminate Chagas' disease subjects examined in a Brazilian endemic area. METHODS: Variability in time and frequency domain of 5-minute electrocardiogram (ECG) series of R-R intervals in supine and active standing positions were obtained from 18 age-, gender-, body mass index-, lifestyle-, and physical activity-matched chagasics and 18 control healthy subjects examined in Agua Comprida city, MG, Brazil. Mann-Whitney test was used for analysis of the data and spread of the individual indices in both groups. RESULTS: The median of the all variability indices in the chagasic group were statistically similar (P= 0.17-0.87) to that in the control group. A wide dispersion of the almost all individual indices values, ranging from normal to variably reduced or increased ones, was noted in the majority of the chagasics in relation to the control interquartile range, in both postural positions. CONCLUSION: As a group, indeterminate Chagas' disease subjects showed unaltered short-term heart interval variability. Individual somewhat widespread of majority of time- and frequency-domain indices, from depressed to exacerbated ones appears to exist. This conforms to a variable cardiac autonomic modulation in this form of disease, suggesting that the majority of chagasics has no lesions, and a minority has subtle lesions of the efferent innervation-sinus node complex.

Effects of pravastatin on the in vitro phagocytic function and hydrogen peroxide production by monocytes of healthy individuals.

Macrophages play a part in pathogenesis of atherosclerosis, oxidizing LDL-cholesterol and transforming themselves in foam cells and producing free radicals of oxygen that may also oxidize LDL-cholesterol. HMG-CoA reductase inhibitors are very efficient in long-term control of atherogenesis acting by different mechanisms not fully established. Thus, we investigated the in vitro influence of pravastatin on phagocytosis and hydrogen peroxide production by monocytes of healthy individuals. Phagocytosis of Saccharomyces erevisiae by peripheral blood monocytes of 20 healthy individuals was assessed in the absence or presence of pravastatin. Hydrogen peroxide production was assessed based on the horseradish peroxidase-dependent oxidation of phenol red method. Pravastatin had no influence on phagocytosis through scavenger receptors, while it decreased by 20% the mean+/-SD phagocytic index of monocytes through complement receptors, from 141+/-77 to 113+/-56 (p=0.017), due to a decrease in the number of particles ingested by monocytes, from 2.1+/-0.5 to 1.7+/-0.3 (p=0.003). This statin also decreased the baseline production of hydrogen peroxide, by 7.7%, from 0.098+/-0.013 to 0.091+/-0.013 (OD by 2x10(5) monocytes per hour) (p=0.025). Pravastatin was able to decrease the phagocytosis through complement receptors and caused a decrease in the production of hydrogen peroxide by monocytes. It is possible this statin may directly inhibit the development of atherosclerotic plaque and its instability dependent on phagocytosis and the presence of reactive species of oxygen.

Digitalis inhibits and furosemide does not change the in vitro phagocytic function of neutrophils of healthy subjects.

This work evaluated the in vitro influence of digitalis and furosemide on the phagocytic function of neutrophils of healthy individuals. Phagocytosis of Saccharomyces cerevisiae by peripheral blood neutrophils of 20 healthy individuals was assessed in the absence or presence of deslanoside or furosemide. The Wilcoxon test was employed to compare the data expressed as median and extreme values. Digitalis reduced the number of yeasts ingested by neutrophils (2.23, 1.23-4.01 versus 1.89, 0.87-2.79; p = 0.019). It did not influence the percentage of these cells engaged in phagocytosis, although there was a tendency for reduction (71%, 23-95% versus 57%, 8-93%; p = 0.11), which resulted in decreasing the phagocytic index from 192 (30-381) to 125 (10-218) (p = 0.028). Furosemide had no significant influence on the number of S. cerevisiae phagocytosed (2.23, 1.23-4.01 versus 1.96, 0.70-4.45; p = 0.89), the percent of phagocytosing neutrophils (71%, 23-95% versus 73%, 9-96%; p = 0.86) and the phagocytic index (192, 30-381 versus 152, 10-428; p = 0.95). These findings indicate the inhibitory influence of digitalis on in vitro neutrophil phagocytic function of healthy subjects, and suggest that this effect might impair the innate immune defense response. On this basis, they could contribute to improve digitalis therapy and advise that this drug class should not be associated with other drugs that may also impair the immune function, or might be used with caution or even avoided in subjects with infections.

Impaired autonomic control of heart interval changes to Valsalva manoeuvre in Chagas' disease without overt manifestation.

BACKGROUND: In the apparent indeterminate form of Chagas' disease, which lacks any overt clinical, electrocardiographic, and radiological manifestations of organ damage, lesions of the intrinsic autonomic innervation of heart are not striking features and evidences for cardiac autonomic dysfunction are elusive and conflicting. OBJECTIVE: To evaluate the cardiac autonomic modulation based on Valsalva manoeuvre-associated heart interval variation in Chagas' disease subjects with apparent indeterminate form. SUBJECTS AND METHODS: We examined 36 outpatient volunteers aged 15-51 years old (median: 36.5), in comparison with 52 healthy control individuals aged 17-49 years old (median: 29) (p<0.001). Each subject sequentially performed in the supine position three to four manoeuvres at an intra-oral pressure of 40 mm Hg during 20 s, under continuous DII lead electrocardiographic registration, and rate- and time-dependent indices of Valsalva manoeuvre-associated R-R interval variation were obtained. The t-test or the Mann-Whitney test was employed to compare the data between the groups. RESULTS: No correlation was found between every index and age for the control group (p=0.39-0.71). The chagasic group presented similar basal to phase IV median increment (relative bradycardia) (23.7% vs. 22.7%; p = 0.63) and smaller basal to phase III median decrement of R-R interval (relative tachycardia) (-31.7% vs. - 35%; p=0.02) in comparison to the control group, respectively. The median Valsalva ratio showed a tendency for reduction in chagasics (1.78 vs. 1.90; p = 0.08). Prolonged median time (14.2 vs. 10.3 s; p < 0.001) and slowed median velocity (5.1%/s vs. 8.9%/s; p < 0.001) of the phases III-IV bradycardia were also observed in chagasic group. The majority (58.3%) of the chagasics presented exclusively at least one depressed, and 8.3% presented at least one enhanced index of rate- and/or time-dependent heart interval responses beyond the 25th or 75th control percentiles, and 27.8% presented at least one depressed and other enhanced index, while 5.6% showed all indices within the control interquartile range. All the indices outside the 25th or 75th control percentiles were noted in 13.9% of chagasics. CONCLUSION: Chagas' disease subjects without overt manifestations presented variable and subtle depression and less frequent enhancement or normality of the rate- and time-dependent tachycardia and bradycardia reflex responses related to Valsalva manoeuvre, which demonstrates distinct patterns of finely disturbed cardiac sinus parasympathetic and sympathetic modulation, probably due to inflammatory or autoimmunological damage of intrinsic innervation and/or to autoantibodies-induced derangement in neurotransmitter receptors.