Software development to standardize the clinical diagnosis of exercise oscillatory ventilation in heart failure

BACKGROUND

Exercise oscillatory ventilation (EOV) is characterized by periodic oscillations of minute ventilation during cardiopulmonary exercise testing (CPET). Despite its prognostic value in chronic heart failure (HF), its diagnosis is complex due to technical limitations. An easier and more accurate way of EOV identification can contribute to a better approach and clinical diagnosis. This study aims to describe a software development to standardize the EOV diagnosis from CPET's raw data in heart failure patients and test its reliability (intra- and inter-rater).

METHODS

The software was developed in the "drag-and-drop" G-language using LabVIEW®. Five EOV definitions (Ben-Dov, Corrà, Kremser, Leite, and Sun definitions), two alternative approaches, one smoothing technique, and some basic statistics were incorporated into the interface to visualize four charts of the ventilatory response. EOV identification was based on a set of criteria verified from the interaction between amplitude, cycle length, and oscillation time. Two raters analyzed the datasets. In addition, repeated measurements were verified after six months using about 25% of the initial data. Cohen's kappa coefficient (κ) was used to investigate the reliability.

RESULTS

Overall, 391 tests were analyzed in duplicate (inter-rater reliability) and 100 tests were randomized for new analysis (intra-rater reliability). High inter-rater (κ > 0.80) and intra-rater (κ > 0.80) reliability of the five EOV diagnoses were observed.

CONCLUSION

The present study proposes novel semi-automated software to detect EOV in HF, with high inter and intra-rater agreements. The software project and its tutorial are freely available for download.

Sensitivity and specificity of different exercise oscillatory ventilation definitions to predict 2-year major adverse cardiovascular outcomes in chronic heart failure patients

BACKGROUND

Exercise oscillatory ventilation (EOV) shows a four-fold greater risk of adverse events. This study aims to analyze the sensitivity and specificity of three EOV diagnostic definitions to predict adverse outcomes at a 2-year follow-up and to compare its EOV prevalence and relations with the patient's profile.

METHODS

Cardiopulmonary exercise tests from 233 heart failure patients were analyzed. Two blinded reviewers used a semiautomated software to identify EOV cases pattern according to the definitions of Ben-Dov, Corrà, and Leite. Data were grouped in EOV-positive or EOV-negative according to each definition. Baseline characteristics, EOV prevalence, relative risk, sensitivity, and specificity to predict 2-years of major adverse cardiovascular outcomes were analyzed.

RESULTS

The Corrà definition led to the best prediction of 2-year major cardiovascular adverse outcomes (HR 2.46 [1.16 to 5.25]; p = 0.019, AUC = 0.618; p = 0.007). EOV prevalence was 17.2%, 17.2%, and 9.4% applying Ben-Dov, Corrà, and Leite definition, respectively. The main clinical differences between EOV-positive and EOV-negative patients were: MECKI score and VE/VCO₂ slope (all definitions), and BNP levels (Ben-Dov and Leite). BNP levels were correlated with amplitude (rho = 0.255; p = 0.033) and cycle length (rho = 0.388; p = 0.002).

CONCLUSION

Corrà definition was the only one that exhibited the capacity to predict major adverse cardiovascular outcomes at a 2-year follow-up. Regardless of its definition, EOV was more often prevalent in patients with a greater MECKI score and VE/VCO₂ slope values.

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.

Agreement between heart rate at first ventilatory threshold on treadmill and at 6-min walk test in coronary artery disease patients on β-blockers treatment

The purpose of this study was to verify the accuracy of the agreement between heart rate at the first ventilatory threshold (HR_VT1) and heart rate at the end of the 6-min walk test (HR_6MWT) in coronary artery disease (CAD) patients on β-blockers treatment. This was a cross-sectional study with stable CAD patients, which performed a cardiopulmonary exercise test (CPET) on a treadmill and a 6-min walk test (6MWT) on nonconsecutive days. The accuracy of agreement between HR_VT1 and HR_6MWT was evaluated by Bland–Altman analysis and Lin’s concordance correlation coefficient (r_c), mean absolute percentage error (MAPE), and standard error of estimate (SEE). Seventeen stable CAD patients on β-blockers treatment (male, 64.7%; age, 61±10 years) were included in data analysis. The Bland–Altman analysis revealed a negative bias of −0.41±6.4 bpm (95% limits of agreements, −13 to 12.2 bpm) between HR_VT1 and HR_6MWT. There was acceptable agreement between HR_VT1 and HR_6MWT (r_c=0.84; 95% confidence interval, 0.63 to 0.93; study power analysis=0.79). The MAPE of the HR_6MWT was 5.1% and SEE was 6.6 bpm. The ratio HR_VT1/HR_peak and HR_6MWT/HR_peak from CPET were not significantly different (81%±5% vs. 81%±6%, P=0.85); respectively. There was a high correlation between HR_VT1 and HR_6MWT (r=0.85, P<0.0001). Finally, the results of the present study demonstrate that there was an acceptable agreement between HR_VT1 and HR_6MWT in CAD patients on β-blockers treatment and suggest that HR_6MWT may be useful to prescribe and control aerobic exercise intensity in cardiac rehabilitation programs.

Short-term aerobic training improves heart rate variability in men living with HIV: a pre-post pilot study

BACKGROUND

Heart rate variability (HRV) a feasible predictor of prognosis in cardiovascular outcomes shown to be reduced in people living with HIV (PLWH).

OBJECTIVE

This study sought to understand the effects of short-term aerobic training (AT) on the resting HRV and endothelial function in this population.

METHODS

PLWH performed 24 sessions of AT protocol. The protocol consists of 40 min of treadmill (60 to 80% of the VO_2max), 3 times per week, for 8 weeks. HRV (standard deviation of all normal RR intervals - SDNN; root mean square of the successive differences - rMSSD; low frequency - LF; high frequency - HF; LF:HF ratio) and endothelial function parameters were evaluated by EndoPAT system pre and post intervention.

RESULTS

7 men, the median age of the sample was 49 years (range, 38-68 years), completed the protocol. AT improved resting HRV parameters: SDNN (p = 0.02, power analysis (PA) 0.54), rMSSD (p = 0.02, PA = 0.99), LF (p = 0.02, PA = 0.85). HF, LF:HF ratio and endothelial function parameters showed no changes.

CONCLUSIONS

The results suggest the short-term AT may improve HRV in men living with HIV.

[Dietary intake and cardiovascular risk among people living with HIV/AIDS]

This cross-sectional study evaluated the food intake patterns related to cardiovascular risk disease among people living with HIV/AIDS (PLWHA) with viral suppression and receiving highly active antiretroviral therapy (HAART). Food intake was obtained by the annual food frequency questionnaire, separated into two groups, healthy and unhealthy food related intake and cardiovascular disease. Data were analyzed using Student's t Test for independent samples or the Mann-Whitney U Test and Fisher's exact test, with a significance level of p < 0.05. The sample consisted of 45 individuals with HIV/AIDS (60% female). The intake of unhealthy foods for cardiovascular risk was greater compared to the intake of healthy foods, both in men (3.91 ± 0.26 vs. 2.79 ± 0.32 p = 0.01) and women (3.40 ± 0.23 vs. 2.60 ± 0.29 p = 0.04). Metabolic syndrome prevalence was 33.3% in men and 37% in women. Men presented hypertriglyceridemia (50%) and low HDL (44%) and women presented central obesity (54%, p = 0.05 vs. men) hypercholesterolemia (66.7% p = 0.02 vs. men) and hypertriglyceridemia (46%). Study results indicate the presence of unhealthy food intake patterns and a high prevalence of cardiovascular risk factors in the evaluated subjects.

Exercise training reduces oxidative stress in people living with HIV/AIDS: a pilot study

BACKGROUND

Exercise training has been shown to be an effective strategy to balance oxidative stress status; however, this is underexplored in people living with HIV/AIDS (PLWHA).

OBJECTIVE

To evaluate the effects of exercise training on oxidative stress in PLWHA receiving antiretroviral therapy.

METHODS

Patients performed 24 sessions (3 times per week, 8 weeks) of either aerobic (AT), resistance (RT), or concurrent training (CT). Glutathione disulphide to glutathione ratio (GSSG/GSH) in circulating erythrocytes and thiobarbituric acid-reactive substances (TBARS) in plasma samples were assessed as oxidative stress markers. Eight PLWAH completed the training protocol (AT =3, RT =3, CT =2). The GSSG/GSH and TBARS values were logarithmically transformed to approximate a normal distribution. A paired t-test was used to determine the differences between baseline and post-training values.

RESULTS

Data-pooled analysis showed a decrease in GSSG/GSH and TBARS after the training period: log GSSG/GSH= -1.26 ± 0.57 versus -1.54 ± 0.65, p = .01 and log TBARS =0.73 ± 0.35 versus 0.43 ± 0.21, p = .01. This was paralleled by a rise in peak oxygen uptake (VO_2peak = 29.14 ± 5.34 versus 32.48 ± 5.75 ml kg^-1 min^-1, p = .04). All the subjects who performed resistance exercises showed an average gain of 37 ± 8% in muscle strength with no difference between performing single or multiple sets in terms of muscle strength gain. The results reinforce the clinical importance of exercise as a rehabilitation intervention for PLWHA and emphasizes the safety of exercise at the physiological level with the potential to mediate health outcomes.

Functional capacity and ventilatory efficiency are preserved in well-controlled people living with human immunodeficiency virus/acquired immunodeficiency syndrome

To verify and compare the responses of the cardiopulmonary variables to the incremental test in physically inactive people living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) (PLWHA) with well-controlled disease and physically inactive healthy subjects (non-HIV/AIDS). Participants performed a cardiopulmonary exercise test (CPX) on a treadmill. Data were analyzed using the Mann–Whitney test and Spearman correlation. Nine PLWHA (5 women) and 9 non-HIV/AIDS gender and activity level-matched controls were included in the data analysis. Data are expressed in median (range). No difference was shown in the PLWHA group when compared to the control group in functional capacity (peak oxygen consumption [VO_2peak]: 29.9 (20.9–36.4) mL/kg/min vs. 32.2 (24.5–39.4) mL/kg/min) and ventilatory efficiency (oxygen uptake efficiency slope [OUES]: 2,058 [1,474–3,204] vs. 2,612 [1,383–4,119]; minute ventilation carbon dioxide production slope: 27.4 [22.5–33.6] vs. 27.5 [20.4–38.1]). The results are also similar to maximal heart rate, oxygen pulse, gas exchange threshold, respiratory compensation point, heart rate recovery, and half-time of VO_2peak recovery. OUES had a strong correlation with VO_2peak in the PLWHA group (r_s=0.70, P=0.04) and control group (r_s=0.78, P=0.02). The results of this study indicate that functional capacity and ventilatory efficiency in PLWHA with well-controlled disease are preserved and are not different from sedentary subjects. In this sense, when CPX is unavailable, the aerobic assessment and prescription could be based on simpler procedures used in healthy subjects.

Can RR intervals editing and selection techniques interfere with the analysis of heart rate variability?

BACKGROUND

Oscillation between successive sinus beats or RR intervals, termed heart rate variability, is an important marker of autonomic function of the heart. However, its analysis may be influenced by the database recorded based on the occurrence of interference.

OBJECTIVE

To evaluate if the techniques of identification and editing of artifacts, as well as the selection methods of RR intervals, can interfere with heart rate variability analysis.

METHODS

The RR intervals of 56 subjects (30 aortic stenosis patients, 14 physically active individuals, 12 amateur athletes) were recorded for 10min using a heart rate monitor. Values with differences greater than 20%, higher than three standard deviations or outside of the normal curve (95% confidence interval) were considered artifacts. These points were corrected through data replacement, adjacent, linear and polynomial interpolation, or excluded. Then, the 256 highest stability points and the last 5min of recordings were chosen. The software programs, Kubios HRV and GraphPAD, were used to calculate and to analyze the indices of heart rate variability, respectively.

RESULTS

Strong agreement was observed among the identification algorithms; there was no difference between the correction techniques (p=0.95); and the selection methods exhibited different sections (p<0.01) with a direct influence on approximated entropy (p<0.05).

CONCLUSION

With short-term recordings, selection methods may interfere with the non-linear heart rate variability analysis. The confidence interval, the replacement by the average of previous data and the selection of 256 of the highest stability points of the signal seem to be the most adequate procedures to treat the data with prior to analysis.

HIV/AIDS e Treinamento Concorrente: a Revisão Sistemática

O uso da terapia anti-retroviral combinada (TARV) aumentou a expectativa de vida dos portadores do vírus da imunodeficiência humana (HIV) e, como conseqüência, torna-se constante o estudo do processo fisiopatológico da infecção e das estratégias de intervenção que possam melhorar a qualidade de vida destes indivíduos. O treinamento concorrente, definido como a associação dos componentes aeróbios e força na mesma sessão de exercícios pode ser inserido neste contexto. O objetivo deste artigo é revisar os aspectos centrais da infecção pelo HIV e as evidências existentes sobre o treinamento concorrente com séries múltiplas e simples nos parâmetros imunológico, virológico, cardiorrespiratório e neuromuscular de pessoas infectadas pelo HIV. O método utilizado foi uma revisão sistemática, com artigos publicados entre 2000-2007, nas bases de dados scielo e pubmed e também em dissertações e teses da biblioteca digital da educação física, esporte e saúde. As evidências científicas encontradas nos 8 estudos analisados indicam que o treinamento concorrente, tanto com séries múltiplas quanto séries simples, melhora os parâmetros cardiorrespiratório e neuromuscular; no entanto, os resultados dos parâmetros imunológico e virológico ainda não estão completamente esclarecidos, principalmente sobre os protocolos com séries simples. Considerando o número restrito de trabalhos apresentados, sugere-se o desenvolvimento de estudos com treinamento concorrente em vários desfechos clínicos para pessoas infectadas pelo HIV.

O estresse oxidativo e o exercício físico em indivíduos HIV positivo

A infecção pelo vírus da imunodeficiência humana (HIV) é acompanhada por alterações estruturais e funcionais relacionadas ao sistema imunológico. Além disso, o aumento do estresse oxidativo (EO) nos portadores do HIV, caracterizado por diminuição nos níveis de glutationa (GSH), aumentos na glutationa oxidada (GSSG), na razão GSSG/GSH e lipoperoxidação, bem como redução da atividade de enzimas antioxidantes - catalase, superóxido dismutase (SOD) e glutationa peroxidase (GPx) - é uma conseqüência da evolução dos pacientes infectados com HIV. As células do sistema imunológico necessitam de altas concentrações de antioxidantes para manter o balanço redox e preservar a sua integridade e função. Quando ocorre a depleção dos antioxidantes, há diminuição da resposta imunológica e aumento na replicação do HIV. O uso da terapia anti-retroviral combinada (TARV) melhorou significativamente a evolução clínica dos pacientes, porém, mesmo assim, alguns continuam apresentando EO aumentado e outros efeitos da TARV, como alterações no metabolismo lipídico e muscular. O treinamento físico é utilizado como intervenção não farmacológica nos pacientes infectados pelo HIV para proporcionar melhoria nos parâmetros antropométricos, aeróbios, musculares e psicológicos, porém, há carência de estudos sobre a sua utilização em relação ao estresse oxidativo. Nesta revisão, foram analisados os tópicos referentes ao estresse oxidativo nos pacientes HIV positivos e os possíveis benefícios do exercício físico na capacidade antioxidante. O treinamento físico é uma estratégia auxiliar para os pacientes, com ou sem uso da TARV, uma vez que melhora os aspectos cardiorrespiratórios, musculares, antropométricos e psicológicos sem induzir a imunossupressão. Referindo-se ao estresse oxidativo, infere-se, a partir dos dados em indivíduos HIV negativos, que o treinamento físico pode gerar adaptações que minimizam os efeitos deletérios provocados pelo EO através de melhorias nos níveis das defesas antioxidantes enzimáticas e não enzimáticas.