Deep breathing heart rate variability is associated with inspiratory muscle weakness in chronic heart failure

Electrocardiographic features of children with Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a clinically common X-linked recessive myopathy, which is caused by mutation of the gene encoding dystrophin on chromosome Xp21. The onset of heart injury in children with DMD is inconspicuous, and the prognosis is poor once it develops to the stage of heart failure. Cardiovascular complications remain an important cause of death in this patient population. At present, population and animal studies have suggested that Electrocardiogram (ECG) changes may be the initial manifestation of cardiac involvement in children with DMD. Relevant clinical studies have also confirmed that significant abnormal ECG changes already exist in DMD patients before cardiomegaly and/or LVEF decrease. With increases in age and decreases in cardiac function, the proportion of ECG abnormalities in DMD patients increase significantly. Some characteristic ECG changes, such as ST-segment changes, T wave inversion, Q wave at the inferolateral leads, LBBB and SDANN, have a certain correlation with the indexes of cardiac remodeling or impaired cardiac function in DMD patients, while VT and LBBB have demonstrated relatively good predictive value for the occurrence of long-term DCM and/or adverse cardiovascular events or even death in DMD patients. The present review discusses the electrocardiographic features in children with DMD.

Impact of chronic obstructive pulmonary disease on linear and nonlinear dynamics of heart rate variability in patients with heart failure

The objective of this study was to investigate the impact of chronic obstructive pulmonary disease (COPD)-heart failure (HF) coexistence on linear and nonlinear dynamics of heart rate variability (HRV). Forty-one patients (14 with COPD-HF and 27 HF) were enrolled and underwent pulmonary function and echocardiography evaluation to confirm the clinical diagnosis. Heart rate (HR) and R-R intervals (iRR) were collected during active postural maneuver (APM) [supine (10 min) to orthostasis (10 min)], respiratory sinus arrhythmia maneuver (RSA-M) (4 min), and analysis of frequency domain, time domain, and nonlinear HRV. We found expected autonomic response during orthostatic changes with reduction of mean iRR, root mean square of successive differences between heart beats (RMSSD), RR tri index, and high-frequency [HF (nu)] and an increased mean HR, low-frequency [LF (nu)], and LF/HF (nu) compared with supine only in HF patients (P<0.05). Patients with COPD-HF coexistence did not respond to postural change. In addition, in the orthostatic position, higher HF nu and lower LF nu and LF/HF (nu) were observed in COPD-HF compared with HF patients. HF patients showed an opposite response during RSA-M, with increased sympathetic modulation (LF nu) and reduced parasympathetic modulation (HF nu) (P<0.05) compared with COPD-HF patients. COPD-HF directly influenced cardiac autonomic modulation during active postural change and controlled breathing, demonstrating an autonomic imbalance during sympathetic and parasympathetic maneuvers compared with isolated HF.

Inspiratory Muscle Training in Patients with Heart Failure

Background: Prior systematic reviews and meta-analysis addressed that inspiratory muscle training (IMT) improved inspiratory muscle weakness, cardiorespiratory fitness and quality of life similar to conventional exercise training as a first alternative in deconditioned patients with heart failure (HF) lead to a better adaptation to posterior exercise training. The heterogeneity and variability in a wide range of new studies about this topic led to the necessity of an updated and comprehensive narrative review. The present review aimed to analyze and update the most relevant studies about IMT in patients who suffer from HF. Methods: A narrative review was carried out about IMT in HF patients including 26 experimental studies divided into 21 clinical trials and 5 quasi-experimental studies identified through database searching in PubMed, Cochrane and PEDro. Results: There is enough evidence to state that IMT produces improvements in functional capacity of patients with HF. Nevertheless, there is not enough evidence to support that IMT could improve cardiovascular parameters, blood biomarkers or quality of life in these patients. Conclusions: Thus, IMT may be recommended to improve functional capacity in patients who suffer from HF; nevertheless, more evidence is needed regarding cardiovascular parameters, biomarkers and quality of life. Furthermore, mortality or HF hospitalization was not evaluated and most studies were not longer than 3 months. According to IMT protocols and study designs heterogeneity and mid-term follow-up, further investigations through high-quality long-term randomized clinical trials should be performed to achieve systematic reviews and meta-analysis to support strong evidence for IMT in HF patients.

A Randomized, 8-Week Study of the Effects of Extended-Release Paliperidone and Olanzapine on Heart Rate Variability in Patients With Schizophrenia

PURPOSE

This study aimed to explore the effect of extended-release paliperidone (paliperidone ER) and olanzapine on heart rate variability (HRV) in patients with schizophrenia.

METHODS

A total of 106 patients with schizophrenia diagnosed by the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) were randomly divided into the paliperidone ER group or the olanzapine group for an 8-week clinical trial, with 53 patients in each group. The time domain and frequency domain analyses including the SD of all the R-R intervals in 24 hours (SDNN), the SD of the mean value of all the normal R-R intervals in every 5-minute interval within 24 hours (SDANN index), the mean value of the SD of all the normal R-R intervals in every 5-minute interval within 24 hours (SDNN index), the root mean square of successive R-R differences, the percentage of adjacent R-R intervals that differ by more than 50 milliseconds, high-frequency power (HF), low-frequency power (LF), and LF/HF were adopted to assess the HRV of patients at baseline and after treatment for 8 weeks in each group. The Positive and Negative Symptom Scale was used to evaluate the clinical efficacy. The incidence rates of adverse reactions were also calculated.

RESULTS

In total, 48 patients in the paliperidone ER group and 45 patients in the olanzapine group completed the entire 8-week treatment. The SDNN, SDNN index, and SDANN index in the olanzapine group were significantly lower than those in the paliperidone ER group (P < 0.05) after treatment for 8 weeks, whereas their mean LF level was higher than that in the paliperidone ER group (P < 0.05) after completion of treatment. Patients in the olanzapine group showed a significant decrease in the SDNN, SDANN index, and SDNN index as well as a statistical increase in the LF and LF/HF in comparison with the pretreatment values (P < 0.05), whereas patients in the paliperidone ER group showed a decrease in the SDANN index and a statistical increase in the LF in comparison with the pretreatment values (P < 0.05).

CONCLUSION

The HRV of patients with schizophrenia changes when they are administered with paliperidone ER or olanzapine, and more attention should be paid to their cardiac autonomic function when using these 2 antipsychotics.

Cardiorespiratory interactions in humans and animals: rhythms for life

The cardiorespiratory system exhibits oscillations from a range of sources. One of the most studied oscillations is heart rate variability, which is thought to be beneficial and can serve as an index of a healthy cardiovascular system. Heart rate variability is dampened in many diseases including depression, autoimmune diseases, hypertension, and heart failure. Thus, understanding the interactions that lead to heart rate variability, and its physiological role, could help with prevention, diagnosis, and treatment of cardiovascular diseases. In this review, we consider three types of cardiorespiratory interactions: respiratory sinus arrhythmia (variability in heart rate at the frequency of breathing), cardioventilatory coupling (synchronization between the heart beat and the onset of inspiration), and respiratory stroke volume synchronization (the constant phase difference between the right and the left stroke volumes over one respiratory cycle). While the exact physiological role of these oscillations continues to be debated, the redundancies in the mechanisms responsible for its generation and its strong evolutionary conservation point to the importance of cardiorespiratory interactions. The putative mechanisms driving cardiorespiratory oscillations as well as the physiological significance of these oscillations will be reviewed. We suggest that cardiorespiratory interactions have the capacity to both dampen the variability in systemic blood flow as well as improve the efficiency of work done by the heart while maintaining physiological levels of arterial CO2. Given that reduction in variability is a prognostic indicator of disease, we argue that restoration of this variability via pharmaceutical or device-based approaches may be beneficial in prolonging life.

Heart Rate Variability and Cardiopulmonary Dysfunction in Patients with Duchenne Muscular Dystrophy: A Systematic Review

Duchenne muscular dystrophy (DMD) is a genetic recessive disorder with progressive muscle weakness. Despite the general muscle wasting, degeneration and necrosis of cardiomyocytes have been the main causes of morbidity and death in individuals with DMD. Cardiac failure is generally preceded by disturbances in heart rate variability (HRV), and non-invasive measurement of the autonomic nervous system has been an important tool to predict adverse cardiovascular events. Hence, the application of HRV to study autonomic modulation in DMD individuals, and the establishment of correlations between HRV and heart/lung diseases, age, and mortality will have the potential to improve quality of life and life expectancy of individuals with DMD. In order to evaluate the state of the art in this field, we conducted a systematic search in Medline/PubMed and BVS (virtual library in health) databases. We selected 8 studies using pre-defined criteria and meta-analysis revealed decreased parasympathetic activity and increased sympathetic predominance in individuals with DMD as major observations. Moreover, there is a strong association between diminished HRV and myocardial fibrosis with DMD. These patterns are evident in patients at early-stage DMD and become more prominent as disease severity and age increase. Thus, data minning clearly indicates that HRV assessment can be used as a predictor for sudden death in individuals with DMD. The use of the HRV, which is inexpensive, ubiquitously available in clinics and hospitals, and a non-invasive analysis tool, can save lives and decrease the morbity in DMD by alerting care givers to consider autonomic nervous system intervention.

Inspiratory muscle training improves physical performance and cardiac autonomic modulation in older women

PURPOSE

Aging impairs the autonomic balance reducing the vagal and increasing the sympathetic components of heart rate variability (HRV) and this could be associated with a decline in physical capacity. Inspiratory muscle training (IMT) is a possible tool to attenuate this physical capacity decline in older women. The aim of this study was to investigate the influence of IMT in the older women on physical capacity and autonomic cardiac modulation at rest and post exercise.

METHODS

20 female participants 60-72 years old were randomly allocated in two groups. One group underwent IMT set at 50% of maximum inspiratory pressure (MIP), every day for 4 weeks (IMT-group). The placebo group performed the same training procedure but with a minimal resistance (5% MIP; PLA-group). Every week, the IMT load was readjusted and the HRV evaluated at rest. The six-minute walk test (6MWT) was performed once pre and post IMT-intervention. The IMT-group and PLA-group performed the same test and intervention procedures.

RESULTS

After a 5 weeks intervention, the MIP had significantly improved in the IMT-group but not in the PLA-group (p < 0.01; es = 1.17). The high frequency power of the HRV spectrum had already improved by the second week (p < 0.01; es = 1.13) and remained elevated until the last week of intervention (p < 0.01; es = 1.43). The same positive results were described in 6MWT distance (p = 0.04; es = 0.39) and the change (∆) of heart rate recovery (HRR) from 1 min (p = 0.02; es = 0.68).

CONCLUSION

IMT increases HRV, improves 6MWT distance and HRR.

Heart Rate Spectra Confirm the Presence of Autonomic Dysfunction in Dementia Patients

Recent data suggest autonomic dysfunction in patients suffering dementia. This study evaluated autonomic modulation in dementia patients with and without autonomic involvement, employing ECG spectral analysis in the time-frequency domain (wavelet transform) in supine resting and head-up tilt (HUT) position. Thirty-six patients were prospectively evaluated at the Department of Neurology and Psychiatry, General Hospital of the City of Linz, between 2009 and 2014. A standard cardiovascular autonomic test series (Ewing battery) was performed to screen for autonomic dysfunction. The Ewing battery diagnoses were used as reference standard and compared to the diagnostic results obtained by spectral analysis (time-frequency domain) of ECG recordings. Based on the Ewing battery results, 14 patients suffered autonomic dysfunction, while 22 did not. Time frequency domain was accessed by using the continuous wavelet transformation (CWT) with an analytical Morlet mother wavelet in supine resting and HUT position. Within each cohort the modification of spectral components from supine resting to HUT was analyzed reflecting the autonomic modulation. For patients without autonomic dysfunction, a significant increase of autonomic modulation was detected by wavelet transformed ECG recordings (8%, p < 0.05; low frequency content) during HUT compared to supine resting. There was no significant modulation between HUT and supine resting in patients suffering autonomic dysfunction. In dementia patients suffering autonomic dysfunction, CWT identified blunted autonomic regulation only by analysis of ECG recordings without the need to assess other biosignals or tests depending on the patient’s cooperation. Further studies are needed to evaluate whether CWT is a suitable method to support the standard Ewing battery in demented patients.

Complexity of autonomic nervous system function in individuals with COPD

OBJECTIVE

To evaluate autonomic modulation in individuals with COPD, compared with healthy controls, via recurrence plots (RPs) and linear heart rate variability (HRV) indices.

METHODS

We analyzed data on 74 volunteers, who were divided into two groups: COPD (n = 43) and control (n = 31). For calculation of HRV indices, heart rate was measured beat-by-beat during 30 min of supine rest using a heart-rate meter. We analyzed linear indices in the time and frequency domains, as well as indices derived from the RPs.

RESULTS

In comparison with the control group, the COPD group showed significant increases in the indices derived from the RPs, as well as significant reductions in the linear indices in the time and frequency domains. No significant differences were observed in the linear indices in the frequency domains expressed in normalized units or in the low frequency/high frequency ratio.

CONCLUSIONS

Individuals with COPD show a reduction in both sympathetic and parasympathetic activity, associated with decreased complexity of autonomic nervous system function, as identified by RPs, which provide important complementary information in the detection of autonomic changes in this population.

The role of the inspiratory muscle weakness in functional capacity in hemodialysis patients

Introduction

Inspiratory muscle function may be affected in patients with End-Stage Renal Disease (ESRD), further worsening the functional loss in these individuals. However, the impact of inspiratory muscle weakness (IMW) on the functional capacity (FC) of hemodialysis patients remains unknown. Thus, the present study aimed to evaluate the impact of IMW on FC in ESRD patients undergoing hemodialysis.

Materials and methods

ESRD patients on hemodialysis treatment for more than six months were evaluated for inspiratory muscle strength and FC. Inspiratory muscle strength was evaluated based on maximal inspiratory pressure (MIP). IMW was defined as MIP values less than 70% of the predicted value. FC was evaluated using the Incremental Shuttle Walk test (ISWT). Patients whose predicted peak oxygen uptake (VO₂peak) over the distance walked during the ISWT was less than 16mL/kg/min were considered to have FC impairment. Associations between variables were assessed by linear and logistic regression, with adjustment for age, sex, body mass index (BMI), presence of diabetes and hemoglobin level. Receiver-operating characteristic (ROC) analysis was used to determine different cutoff values of the MIP for normal inspiratory muscle strength and FC.

Results

Sixty-five ERSD patients (67.7% male), aged 48.2 (44.5–51.9) years were evaluated. MIP was an independent predictor of the distance walked during the ISWT (R² = 0.44). IMW was an independent predictor of VO₂peak < 16mL/kg/min. (OR = 5.7; p = 0.048) in adjusted logistic regression models. ROC curves showed that the MIP cutoff value of 82cmH₂O had a sensitivity of 73.5% and specificity of 93.7% in predicting normal inspiratory strength and a sensitivity and specificity of 76.3% and 70.4%, respectively, in predicting VO₂peak ≥ 16mL/kg/min.

Conclusions

IMW is associated with reduced FC in hemodialysis patients. Evaluation of the MIP may be important to functional monitoring in clinical practice and can help in the stratification of patients eligible to perform exercise testing.

Respiratory Muscle Training Improves Chemoreflex Response, Heart Rate Variability, and Respiratory Mechanics in Rats With Heart Failure

BACKGROUND

The aim of the present report was to evaluate respiratory muscle training (RMT) effects on hemodynamic function, chemoreflex response, heart rate variability, and respiratory mechanics in rats with heart failure (HF rats).

METHODS

Wistar rats were divided into 4 groups: sedentary-sham (Sed-Sham, n = 8), respiratory muscle trained-sham (RMT-Sham, n = 8), sedentary-HF (Sed-HF, n = 8) and respiratory muscle trained-HF (RMT-HF, n = 8). Animals were submitted to an RMT protocol performed 30 minutes per day, 5 days per week for 6 weeks, whereas the sedentary animals did not exercise.

RESULTS

In HF rats, RMT promoted the reduction of left ventricular end-diastolic pressure, right ventricular hypertrophy, and pulmonary edema. Moreover, RMT produced a reduction in pressure response during chemoreflex activation, sympathetic modulation, and sympathetic vagal balance in addition to an increase in parasympathetic modulation. Also after RMT, HF rats demonstrated a reduction in respiratory system resistance, tissue resistance, Newtonian resistance, respiratory system compliance, and quasistatic compliance.

CONCLUSIONS

These findings suggested that 6 weeks of RMT in HF rats promoted beneficial adaptations in hemodynamics, autonomic function, and respiratory mechanics and attenuated pressure response evoked by chemoreflex activation in HF rats.

High-Intensity Inspiratory Protocol Increases Heart Rate Variability in Myocardial Revascularization Patients

Objective:

To evaluate heart rate variability during an inspiratory muscle endurance protocol at three different load levels [30%, 60% and 80% of maximal inspiratory pressure], in patients who had previously undergone coronary artery bypass grafting.

Methods:

Nineteen late postoperative myocardial revascularization patients participating in a cardiovascular rehabilitation program were studied. Maximal inspiratory pressure maneuvers were performed. An inspiratory muscle endurance protocol at 30%, 60% and 80% of maximal inspiratory pressure was applied for four minutes each, in random order. Heart rate and RR intervals were recorded and heart rate variability was analyzed by time (RMSSD-the mean of the standard deviations for all R-R intervals, and RMSM-root-mean square differences of successive R-R intervals) and frequency domains indices (high and low frequency) in normalized units. ANOVA for repeated measurements was used to compare heart rate variability indices and Student t-test was used to compare the maximal inspiratory pressure and maximal expiratory pressure values.

Results:

Heart rate increased during performance of maximal respiratory pressures maneuvers, and the maximal inspiratory pressure and maximal expiratory pressure mean values were significantly lower than predicted values (P<0.05). RMSSD increased significantly at 80% in relation to rest and 30% of maximal inspiratory pressure and RMSM decreased at 30% and 60% of maximal inspiratory pressure in relation to rest (P<0.05). Additionally, there was significant and progressive decrease in low frequency and increase in high frequency at 30%, 60% and 80% of maximal inspiratory pressure in relation to the resting condition.

Conclusion:

These results suggest that respiratory muscle training at high intensities can promote greater parasympathetic activity and it may confer important benefits during a rehabilitation program in post-coronary artery bypass grafting.

Respiratory muscle strength effect on linear and nonlinear heart rate variability parameters in COPD patients

Introduction

Chronic obstructive pulmonary disease (COPD) is recognized as a multisystemic inflammatory disease associated with extrapulmonary comorbidities, including respiratory muscle weakness and cardiovascular and cardiac autonomic regulation disorders. We investigated whether alterations in respiratory muscle strength (RMS) would affect cardiac autonomic modulation in COPD patients.

Methods

This study was a cross-sectional study done in ten COPD patients affected by moderate to very severe disease. The heart rate variability (HRV) signal was recorded using a Polar cardiofrequencimeter at rest in the sitting position (10 minutes) and during a respiratory sinus arrhythmia maneuver (RSA-M; 4 minutes). Linear analysis in the time and frequency domains and nonlinear analysis were performed on the recorded signals. RMS was assessed using a digital manometer, which provided the maximum inspiratory pressure (PImax) and the maximum expiratory pressure (PEmax).

Results

During the RSA-M, patients presented an HRV power increase in the low-frequency band (LFnu) (46.9±23.7 vs 75.8±27.2; P=0.01) and a decrease in the high-frequency band (HFnu) (52.8±23.5 vs 24.0±27.0; P=0.01) when compared to the resting condition. Significant associations were found between RMS and HRV spectral indices: PImax and LFnu (r=−0.74; P=0.01); PImax and HFnu (r=0.74; P=0.01); PEmax and LFnu (r=−0.66; P=0.01); PEmax and HFnu (r=0.66; P=0.03); between PEmax and sample entropy (r=0.83; P<0.01) and between PEmax and approximate entropy (r=0.74; P=0.01). Using a linear regression model, we found that PImax explained 44% of LFnu behavior during the RSA-M.

Conclusion

COPD patients with impaired RMS presented altered cardiac autonomic control, characterized by marked sympathetic modulation and a reduced parasympathetic response; reduced HRV complexity was observed during the RSA-M.

Ajustes cardiorrespiratórios durante a manobra de acentuação da arritmia sinusal respiratória: influência do tempo da manobra sobre o volume minuto, fração expirada de CO2 e variabilidade da frequência cardíaca

RESUMO A frequência cardíaca sofre variações durante o ciclo respiratório, fenômeno conhecido como arritmia sinusal respiratória. A manobra para acentuação da arritmia sinusal respiratória (M-ASR) consiste em manter ventilação educada com uma frequência respiratória de seis ciclos por minuto com relação tempo inspiração/expiração (TI:TE) de 1:1. Este estudo tem como objetivo avaliar o comportamento do volume minuto, da fração expirada de CO2 (FeCO2 infere sobre PaCO2) e do controle autonômico da frequência cardíaca durante a M-ASR com duração maior do que 90s. Foram avaliados 16 homens jovens saudáveis (de 18 a 25 anos). Todos foram orientados a realizar inspirações e expirações lentas com duração de 10 segundos por ciclo, TI:TE de 1:1 e consequente frequência respiratória de seis incursões por minuto, durante quatro minutos. Durante a avaliação foi coletada a frequência cardíaca (FC) batimento a batimento por meio de um cardiofrequencímetro, o volume minuto (VM) e a FeCO2 através de um ergoespirômetro. Para análise estatística empregou-se ANOVA one-way (com post-hoc de Tukey) ou teste de Kruskal-Wallis (com post-hoc de Dunn) quando conveniente (p<0,05). Durante a M-ASR, a FeCO2, o VM e os índices do domínio do tempo da variabilidade da frequência cardíaca (VFC) não sofreram alterações significativas ao longo do tempo. A realização da M-ASR em jovens saudáveis, por mais de 90 segundos, pode ser executada com segurança, sem o risco de hipocapnia e sem a interferência das alterações de FeCO2 nos índices do domínio do tempo da análise de VFC da M-ASR.

Slow breathing influences cardiac autonomic responses to postural maneuver: Slow breathing and HRV

Chronic slow breathing has been reported to improve Heart Rate Variability (HRV) in patients with cardiovascular disorders. However, it is not clear regarding its acute effects on HRV responses on autonomic analysis. We evaluated the acute effects of slow breathing on cardiac autonomic responses to postural change manoeuvre (PCM). The study was conducted on 21 healthy male students aged between 18 and 35 years old. In the control protocol, the volunteer remained at rest seated for 15 min under spontaneous breathing and quickly stood up within 3 s and remained standing for 15 min. In the slow breathing protocol, the volunteer remained at rest seated for 10 min under spontaneous breath, then performed slow breathing for 5 min and rapidly stood up within 3 s and remained standing for 15 min. Slow breathing intensified cardiac autonomic responses to postural maneuver.

Rehabilitation practice patterns for patients with heart failure: the South American perspective

Heart failure (HF) is an important public health issue in South America. Economic impacts are substantial. Chagas heart disease is a prevalent HF etiology; it is caused by the protozoan Trypanosoma cruzi. Cardiac rehabilitation (CR) is an integral component of HF care. The benefits of CR in HF patients need to be assessed. The effectiveness and safety of CR delivery, such as home-based interventions, should be explored. Strategies to improve adherence in CR are imperative. We describe past and current CR trends for HF patients and discuss the future of this important intervention.