Would be the minute ventilation variability an alternative to the dichotomous diagnosis of exercise oscillatory ventilation?

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CAPES and FAPERGS.

Background

Exercise oscillatory ventilation (EOV) is an abnormal ventilatory phenomenon observed in chronic heart failure (HF) patients usually defined as EOV-positive or EOV-negative based on a dichotomous diagnosis. Minute ventilation variability (vVE) can quantify the presence of these oscillations and assist the prognosis of patients.

Purpose

To analyse the sensitivity and specificity of vVE to predict 2-year all-causes of death in HF patients.

Methods

Data from 233 cardiopulmonary exercise tests from HF patients performed between 2011 and 2014 at an Italian heart centre were analysed. The vVE was defined by the standard deviation (SD) of VE normalized by the number of respiratory cycles (SD/n) during the exercise tests. The cut-off to predict 2-year mortality was determined by the receiver-operating characteristic (ROC) curve.

Results

Thirty-five deaths were registered at 2-years. The ROC curve indicated ≤ 54.9 as the better cut-off for vVE (32 deaths were registered in follow-up; Figure 1). The relative risk was 3.9 (1.3 to 12.4) with a hazard ratio of 2.7 (1.3 to 5.6) for 2-year mortality.

Conclusion

The vVE appears to be a sensitive alternative to quantify EOV and stratify high-risk cases from 2-year all-cause mortality.

Brain natriuretic peptide levels are associated with cycle length average and are different between Ben-Dov and Corra exercise oscillatory ventilation definitions in heart failure patients

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CAPES e FAPERGS.

Background

The brain natriuretic peptide (BNP) is a marker of ventricular dysfunction related to severity and prognosis in heart failure patients. Exercise oscillatory ventilation (EOV) is a phenomenon in the ventilatory pattern associated with a worse prognosis in heart failure patients. EOV diagnosis is defined by the interaction among amplitude, cycle length, and the total time of the oscillations. Ben-Dov and Corrà definitions are used to identify EOV-positive cases by different criteria, which may stratify EOV patients with distinct clinical characteristics.

Purpose

To assess the BPN levels in heart failure patients and to test BNP level correlation with amplitude, cycle length, and total oscillation time according to Ben-Dov and Corrà definitions.

Methods

Data from 242 cardiopulmonary exercise tests (CPETs) performed between 2011 and 2014 at an Italian heart centre were screened for EOV identification. CPETs were done in a cycle-ergometer with gas exchange analysed breath-by-breath. EOV cases were identified according to the definitions of Ben-Dov and Corrà. Mann-Whitney test was applied to compare BPN levels between the EOV-positive and negative in each definition and between EOV-positive from Ben-Dov and Corrà definitions. Spearman coefficient (rs) evaluated the association between amplitude and length average of the oscillatory cycle, percentage of total oscillation time, and BNP levels in each EOV definition. The BNP levels from EOV-positive identified by Corrà or Ben-Dov definition alone, and from patients who have met the criteria of both definitions were compared by the Kruskal-Wallis test.

Results

Sixty-seven patients were identified as EOV-positive. From them, 19 were identified exclusively by the Ben-Dov and 26 by Corrà. Twenty-two met the criteria for both definitions. Overall, no difference in EOV prevalence between Ben-Dov and Corrà definitions was found (20.4 vs 24.2%, p = 0.482). EOV-positive identified by the Ben-Dov definition have higher BNP levels than EOV-negative (p < 0.01) and the EOV-positive by Corrà definition (p = 0.025) (Table 1). Spearman correlation showed association just between BNP levels and cycle length average from EOV-positive by the Ben-Dov (rs = 0.566; p < 0.001) and by Corrà (rs = 0.339; p = 0.011) (Figure 1). When analysed by exclusive criteria identification, the BNP levels were higher in EOV-positive identified by Ben-Dov than Corrà (737 [562 to 1,178] vs 276 [221 to 603] pg/mL; p = 0.009). BNP levels in the EOV-positive identified by both definitions (475 [347 to 852] pg/mL) were not different from those identified by the Ben-Dov and Corrà definitions alone.

Conclusion

EOV-positive identified by the Ben-Dov have higher BNP levels than EOV-negative and the EOV-positive identified by Corrà, alone or not. BNP levels also are associated with the cycle length average, with a higher correlation for the Ben-Dov EOV-positive.

The talk test"s responsiveness to an 8-week exercise-training program in cardiovascular disease patients

Funding Acknowledgements

Type of funding sources: None.

Background

Talk test (TT) is an alternative and accessible tool for prescribing and monitoring aerobic training intensity. Although the TT is reliable and valid for cardiorespiratory assessment, its responsiveness to exercise training remains unexplored.

Purpose

To evaluate the responsiveness of TT in cardiovascular disease (CVD) patients who underwent an exercise training program.

Methods

Twenty-one CVD patients (61.7 ± 8.4 years) performed an exercise-training program on phase II of cardiac rehabilitation (45-min 3-times a week). The six-minute walk test (6MWT) and TT were done to assess functional capacity at baseline and after 8 weeks. In the individualized TT the treadmill’s speed and/or grade were increased every 2-min, with speed changes based on a reference equation for the 6MWT distance (6MWD). The subjects were asked to read a 38 words standard paragraph at the last 30s of each stage and to answer if they could talk comfortably. Answer options were i) YES (TT+), ii) UNCERTAIN (TT±), or iii) NO (TT-). The first ventilatory threshold (VT1) was identified by two reviewers using the heart rate variability analysis. A paired t-test was applied to analyze the TT duration and 6MWD. The VT1 and TT workload were analyzed by the Wilcoxon test. Spearman correlation was adopted to compare the TT± and VT1 stages.

Results

Improvement in the VT1 (2.9 ± 1.2 vs 4.4 ± 1.4 min; p < 0.001), duration (12.1 ± 4.4 vs 14.9 ± 5.2 min; p < 0.001), workload at TT- (67.8 ± 48.4 vs 104.5 ± 65.9 w; p < 0.001), and in the 6MWD (471.5 ± 100.3 vs 533.7 ± 92.9 m; p < 0.001) were observed. There was strong correlation between TT± and VT1 in pre (r = 0.613; p < 0.05) and post-rehabilitation (r = 0.678; p < 0.05).

Conclusion

Talk test performed on a treadmill showed responsiveness after eight weeks of exercise training, being sensitive to the physiological changes provided by the rehabilitation program in CVD patients.

Exercise test with constant workload versus incremental test in individuals with cardiovascular disease: systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

Research Group on Cardiovascular Health and Exercise - gepCARDIO

Introduction

Cardiovascular disease is the main cause of morbidity and mortality worldwide, accounting for about 31% of deaths, in addition to leading to disabilities and worsening quality of life. The diagnosis of the disease and the response to treatments can be evaluated with functional tests. The most used are the incremental tests, such as the cardiopulmonary exercise test, a reference standard for diagnostic evaluation and exercise prescription. Constant workload tests or endurance tests report the efforts in daily activities and are especially applied to assess the effects of therapeutic procedures, such as physical training and drug therapy. Porpuse: Compare incremental exercise tests with constant workload tests for the assessment of functional performance in response to therapeutic interventions in individuals with cardiovascular disease. Methods: The systematic review was registered on the PROSPERO (CRD42020190214). The search was conducted in July 2020, in ten databases (PubMed, Scopus, Web of Science, Embase, CINAHL, LILACS, PEDro, SPORTDiscus, Livivo and Cochrane Library), and the Google Scholar search. Combinations of terms of related to the PECO strategy were used: (P) individuals with cardiovascular disease undergoing therapeutic procedure; (E) who were exposed to the evaluation with constant workload test; (C) compared to an incremental exercise test; (O) to assess functional capacity outcomes.  Results: 9.453 studies were identified, of which 24 were included in the qualitative analysis and 19 in the meta-analysis. The interventions found were exercise training (71%) and drug therapy (29%). Heart failure was the prevalent diagnosis (54%), followed by coronary artery disease (17%). The constant workload test showing an improvement of 83% (MD 8.62, 95% CI 5.85–11.38) in test duration. The incremental tests showed changes of 12% (MD 1.98, 95% CI 5.85–11.38) for oxygen uptake, and 23% (MD 2.15, 95% CI 1.60–2.71) in oxygen uptake at the anaerobic threshold. In the comparisons between the tests performed in the meta-analysis, the duration of the constant workload test was more responsive than the oxygen uptake in the incremental test (SMD 1.59, 95% CI 0.88 - 2.29). In the analysis of subgroups of clinical diagnosis, the constant workload test was more responsive in the groups of heart failure, coronary artery disease and peripheral arterial disease. In the analysis by type of intervention, the studies with constant workload test also showed superior results. Conclusion: Tests with constant workload are more responsive in detecting changes in functional capacity in individuals with cardiovascular disease after a therapeutic intervention. Future studies with better methodological quality are recommended to increase the certainty of the evaluated evidence. Constant workload tests may have more use in clinical practice, facilitating the assessment of functional outcomes for cardiac patients.

Frailty impairs the endothelial function of elderly with chronic heart failure

Funding Acknowledgements

Type of funding sources: None.

Background

Frailty has a high prevalence of heart failure (HF). It is believed that existing circulatory disturbance increase oxidative stress and chronic inflammation, predisposing to anabolic-catabolic imbalance. Thus, there is impairment of the efficient use of oxygen by skeletal muscles, limiting the physical-functional performance in these individuals. However, little is known about the influence of frailty on endothelial function in the elderly.

Purpose

To analyze the influence of frailty on endothelial function in the elderly with and without HF.

Methods

This was a descriptive cross-sectional study, which included individuals aged ≥60 years, with or without HF, who did not have diabetes, anemia, peripheral obstructive arterial disease and/or congenital heart disease. The Cardiovascular Health Study (CHS) frailty scale criteria were used to assess frailty (phenotype). Endothelial function at rest was evaluated by near-infrared spectroscopy ([NIRS]; slope 1, lowest tissue oxygen saturation [StO2], area under the curve [AUC] of StO2, slope 2, StO2 peak, overshoot, ΔStO2nadir_peak and Δtime nadir_peak) during arterial occlusion maneuver on the forearm. Results were grouped according to the frailty phenotype: robust, pre-frail and frail. Shapiro-Wilk test was used to assess the normality of data. Quantitative data were compared using a two-way analysis of variance plus Bonferroni post hoc test to determine the influence of the frailty or HF on endothelial function variables. A p-value <0.05 was considered statistically significant.

Results

Fifty-two elderly people (61% women) participated in the study, with a mean age of 70.3 ± 7.1 years. Of these, 52% (n = 27) had a diagnosis of HF. Among the sample, 35% (n = 18) were robust, 45% (n = 23) pre-frail, and 20% (n = 11) frail. Endothelial function analysis identified that there was an influence of frailty on reperfusion rate (slope 2 and ΔStO2 nadir-peak; p < 0.05) and desaturation during arterial occlusion (AUC StO2; p < 0.05) only in the HF group.

Conclusion

The coexistence of frailty and HF seems to impair endothelial function since frail elderly with HF had lower reperfusion rate and higher desaturation during the arterial occlusion test.

Abstract Figure. Endothelial function assessment by NIRS

Muscle oxygenation assessment during talk test to determine the anaerobic threshold in individuals with cardiovascular disease

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.

Background

Cardiopulmonary exercise test (CPET) is the reference method for assessing gas exchange threshold (GET), a surrogate of the anaerobic threshold (AnT). However, muscle oxygenation has been shown as an additional tool for AnT determination, using the lower limb threshold (LLT). Besides, Talk Test (TT), a tool used to assess, prescribe, and monitor exercise intensity through speech comfort level, has shown a correlation with GET as well.

Purpose

To identify the AnT obtained from the traditional method from CPET (GET) and the LLT; to compare heart rate (HR) and tissue saturation index (TSI) data at AnT (GET and LLT); to compare the parameters of LLT on CPET and TT, and to correlate LLT and TT stages in cardiovascular disease (CVD) patients.

Methods

CVD patients underwent CPET and TT, both on a treadmill, in two distinctive days. During those tests, peripheral muscle oxygenation was assessed by the near-infrared spectroscopy method. GET (CPET) was determined by the V-slope method; LLT (CPET and TT) was determined by the visual inspection of oxyhemoglobin and deoxyhemoglobin curves. A TT protocol based on the prediction equation for the covered distance of the six-minute walk test (6MWD) was applied. TT protocol was incremental, with two-minutes stages starting at 70% of the average velocity predicted and 2% of inclination, increasing velocity in 10 percentage points (p.p.) at each stage, until the fifth stage, at which the inclination was increased in 2 p.p. until test completion. At the end of each stage, patients read a standardized paragraph and were asked about speech comfort. Shapiro-Wilk test was performed to assess data distribution. Wilcoxon test was applied to compare physiological variables (HR and TSI) at GET and LLT. Repeated measures analysis of variance (ANOVA), followed by Bonferroni post-hoc test was assessed to compare the variables at LLT and TT stages (last TT+ and first TT±). Spearman correlation coefficient was used to assess the relationship between variables. Statistical significance was set at 5%.

Results

24 cardiovascular patients were included. Similar values of HR (GET vs. LLT: 102 ± 15 bpm vs. 99 ± 14 bpm, p = 0,08), and TSI (GET vs. LLT: 64,6 ± 8,2% vs. 66,4 ± 7,8%, p = 0,09) were observed during CPET. Regarding LLT at CPET and TT, there was no difference between HR (CPET vs. TT: 99 ± 14 bpm vs. 100 ± 12 bpm, p = 1,00) and TSI (CPET vs. TT: 66,4 ± 7,8% vs. 65,3 ± 4,9%, p = 1,00). Furthermore, good relationship between HR in LLT and TT stages (LLT vs. TT+: r = 0,79; LLT vs. TT±: r = 0,76; p < 0,05 for both) was found.

Conclusions

Our results showed similarity between LLT and GET. Besides, TT showed a similar response of muscle oxygenation and heart rate comparing to CPET, with a good correlation between LLT and TT stages. These results endorse the validity of TT as an auxiliary and low-cost tool to identify the AnT.

RXRα is upregulated in first trimester endometrial glands of spontaneous abortions unlike LXR and PPARγ

Nuclear receptors are necessary for uterine invasion of the trophoblast and therefore important for maintaining a viable pregnancy. The aim of this study was to investigate the expression pattern and frequency of LXR, PPARγ and RXRα under physiological circumstances and in spontaneous abortions in endometrial glands and decidual tissue cells. A total of 28 (14 physiologic pregnancies/14 spontaneous abortion) human pregnancies in first trimester were analyzed for expression of the nuclear receptors LXR, RXRα and PPARγ. Expression changes were evaluated by immunohistochemistry in decidual tissue and endometrial glands of the decidua. RXRα expression was up-regulated in the endometrial glands of spontaneous abortion (P<0.015). Similar up regulation of RXRα was found in decidual tissue (P<0.05). LXR and PPARγ expression was unchanged in spontaneous abortion. By Correlation analysis we found a trend to positive correlation of LXR and PPARγ (Spearman correlation coefficient r=0.56, P=0.07) in endometrial glands. In decidual tissue, we found significant negative correlation in the control group, for the combination of RXRα and PPARγ (Spearman correlation coefficient r=0.913, P=0.03). Our data show that RXRα expression is increased in miscarriage in endometrial glands and correlation analysis showed that negative correlation between RXRα and PPARγ disappears in miscarriage. This shift is supposable responsible for the loss of regular function in trophoblast and embryonic tissue.

Investigating population differentiation in a major African agricultural pest: evidence from geometric morphometrics and connectivity suggests high invasion potential

The distribution, spatial pattern and population dynamics of a species can be influenced by differences in the environment across its range. Spatial variation in climatic conditions can cause local populations to undergo disruptive selection and ultimately result in local adaptation. However, local adaptation can be constrained by gene flow and may favour resident individuals over migrants-both are factors critical to the assessment of invasion potential. The Natal fruit fly (Ceratitis rosa) is a major agricultural pest in Africa with a history of island invasions, although its range is largely restricted to south east Africa. Across Africa, C. rosa is genetically structured into two clusters (R1 and R2), with these clusters occurring sympatrically in the north of South Africa. The spatial distribution of these genotypic clusters remains unexamined despite their importance for understanding the pest's invasion potential. Here, C. rosa, sampled from 22 South African locations, were genotyped at 11 polymorphic microsatellite loci and assessed morphologically using geometric morphometric wing shape analyses to investigate patterns of population structure and determine connectedness of pest-occupied sites. Our results show little to no intraspecific (population) differentiation, high population connectivity, high effective population sizes and only one morphological type (R2) within South Africa. The absence of the R1 morphotype at sites where it was previously found may be a consequence of differences in thermal niches of the two morphotypes. Overall, our results suggest high invasion potential of this species, that area-wide pest management should be undertaken on a country-wide scale, and that border control is critical to preventing further invasions.