Reliability and validity of six-minute step test in patients with heart failure

Exercise intolerance is the hallmark consequence of advanced chronic heart failure (HF). The six-minute step test (6MST) has been considered an option for the six-minute walk test because it is safe, inexpensive, and can be applied in small places. However, its reliability and concurrent validity has still not been investigated in participants with HF with reduced ejection fraction (HFrEF). Clinically stable HFrEF participants were included. Reliability and error measurement were calculated by comparing the first with the second 6MST result. Forty-eight hours after participants underwent the 6MST, they were invited to perform a cardiopulmonary exercise test (CPET) on a cycle ergometer. Concurrent validity was assessed by correlation between number of steps and peak oxygen uptake (V̇O2 peak) at CPET. Twenty-seven participants with HFrEF (60±8 years old and left ventricle ejection fraction of 41±6%) undertook a mean of 94±30 steps in the 6MST. Intra-rater reliability was excellent for 6MST (ICC=0.9), with mean error of 4.85 steps and superior and inferior limits of agreement of 30.6 and -20.9 steps, respectively. In addition, strong correlations between number of steps and CPET workload (r=0.76, P<0.01) and peak V̇O2 (r=0.71, P<0.01) were observed. From simple linear regression the following predictive equations were obtained with 6MST results: V̇O2 peak (mL/min) = 350.22 + (7.333 × number of steps), with R2=0.51, and peak workload (W) = 4.044 + (0.772 × number of steps), with R2=0.58. The 6MST was a reliable and valid tool to assess functional capacity in HFrEF participants and may moderately predict peak workload and oxygen uptake of a CPET.

Effect of continuous positive airway pressure associated to exercise on the breathing pattern and heart rate variability of patients undergoing coronary artery bypass grafting surgery: a randomized controlled trial

Continuous positive airway pressure (CPAP) has been used to improve gas exchange and diaphragmatic function, among others benefits. Moreover, it can be used to increase exercise tolerance and positively influence ventilatory function and breathing pattern (BP) during exercise. However, there is no information about the long-term effects of CPAP, as an adjunct to an inpatient cardiac rehabilitation (CR) program, on BP and heart rate variability (HRV) of patients after coronary artery bypass grafting surgery (CABG). Twenty patients were allocated to receive, after randomization, standard inpatient CR without CPAP (control group - CG) or CR with CPAP between 10 to 12 cmH2O (CPAP group - CPG) associated with the exercises. Participants were assessed preoperatively and on the discharge day, in the sitting rest position. Outcome measurements included BP variables, collected by respiratory inductive plethysmography, and HRV, collected by polar precision performance. The CPG presented lower values of percent rib cage inspiratory and expiratory contributions to tidal volume (%RCi and %RCe) at discharge time, compared to CG. No statistical differences between groups were observed for HRV variables and both groups presented lower values of these indices, compared to preoperative ones. In this context, the patients who received CPAP throughout the whole rehabilitation program were discharged with a better BP, which could indicate more synchronized breathing. CPAP did not influence cardiac autonomic modulation in the long term.

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.

Cardiorespiratory and metabolic determinants during moderate and high resistance exercise intensities until exhaustion using dynamic leg press: comparison with critical load

The objective of this study was to assess cardiovascular, respiratory, and metabolic responses during a commonly used dynamic leg press resistance exercise until exhaustion (TEx) at different intensities and compare with critical load (CL). This was a prospective, cross-sectional, controlled, and crossover study. Twelve healthy young men (23±2.5 years old) participated. The subjects carried out three bouts of resistance exercise in different percentages of 1 repetition maximum (60, 75, and 90% 1RM) until TEx. CL was obtained by means of hyperbolic model and linearization of the load-duration function. During all bout intensities, oxygen uptake (VO2), carbon dioxide production (VCO2), ventilation (VE), and respiratory exchange ratio (RER) were obtained. Variations (peak-rest=Δ) were corrected by TEx. In addition, systolic and diastolic blood pressure (SBP and DBP), blood lactate concentration [La-] and Borg scores were obtained at the peak and corrected to TEx. CL induced greater TEx as well as number of repetitions when compared to all intensities (P<0.001). During CL, Borg/TEx, ΔSBP/TEx, ΔDBP/TEx, and [La-] were significantly lower compared with 90% load (P<0.0001). In addition, VO2, VCO2, VE, and RER were higher during CL when compared to 90 or 75%. TEx was significantly correlated with VO2 on CL (r=0.73, P<0.05). These findings support the theory that CL constitutes the intensity that can be maintained for a very long time, provoking greater metabolic and ventilatory demand and lower cardiovascular and fatigue symptoms during resistance exercise.

Cardiac autonomic modulation during progressive upper limb exercise by patients with coronary artery disease

The purpose of this study was to investigate the behavior of heart rate (HR) and HR variability (HRV) during different loads of resistance exercise (incline bench press) in patients with coronary artery disease (CAD) and healthy sedentary controls. Ten healthy men (65 ± 1.2 years, control group, CG) and 10 men with clinically stable CAD (66 ± 2.4 years, CADG) were recruited. A discontinuous progressive protocol was applied with an initial load of 10 percent of the maximum load achieved in the 1RM (1 repetition maximum) with increases of 10 percent until 30 percent 1RM was reached, which was followed by subsequent increases of 5 percent 1RM until exhaustion. HRV was analyzed by linear and non-linear methods. There was a significant reduction in rMSSD (CG: 20 ± 2 to 11 ± 3 ms; CADG: 19 ± 3 to 9 ± 1 ms) and SD1 indexes (CG: 14 ± 2 to 8 ± 1 ms; CADG: 14 ± 2 to 7 ± 1 ms). An increase in HR (CG: 69 ± 5 to 90 ± 5 bpm; CADG: 62 ± 4 to 75 ± 4 bpm) and in systolic blood pressure (CG: 124 ± 3 to 138 ± 3 mmHg; CADG: 122 ± 6 to 126 ± 9 bpm) were observed (P < 0.05) when comparing pre-effort rest and 40 percent 1RM in both groups. Furthermore, an increase in RMSM index was also observed (CG: 28 ± 3 to 45 ± 9 ms; CADG: 22 ± 2 to 79 ± 33 ms), with higher values in CADG. We conclude that loads up to 30 percent 1RM during incline bench press result in depressed vagal modulation in both groups, although only stable CAD patients presented sympathetic overactivity at 20 percent 1RM upper limb exercise.

Effects of different levels of positive airway pressure on breathing pattern and heart rate variability after coronary artery bypass grafting surgery

The application of continuous positive airway pressure (CPAP) produces important hemodynamic alterations, which can influence breathing pattern (BP) and heart rate variability (HRV). The aim of this study was to evaluate the effects of different levels of CPAP on postoperative BP and HRV after coronary artery bypass grafting (CABG) surgery and the impact of CABG surgery on these variables. Eighteen patients undergoing CABG were evaluated postoperatively during spontaneous breathing (SB) and application of four levels of CPAP applied in random order: sham (3 cmH2O), 5 cmH2O, 8 cmH2O, and 12 cmH2O. HRV was analyzed in time and frequency domains and by nonlinear methods and BP was analyzed in different variables (breathing frequency, inspiratory tidal volume, inspiratory and expiratory time, total breath time, fractional inspiratory time, percent rib cage inspiratory contribution to tidal volume, phase relation during inspiration, phase relation during expiration). There was significant postoperative impairment in HRV and BP after CABG surgery compared to the preoperative period and improvement of DFAα1, DFAα2 and SD2 indexes, and ventilatory variables during postoperative CPAP application, with a greater effect when 8 and 12 cmH2O were applied. A positive correlation (P < 0.05 and r = 0.64; Spearman) was found between DFAα1 and inspiratory time to the delta of 12 cmH2O and SB of HRV and respiratory values. Acute application of CPAP was able to alter cardiac autonomic nervous system control and BP of patients undergoing CABG surgery and 8 and 12 cmH2O of CPAP provided the best performance of pulmonary and cardiac autonomic functions.

Atividade autonômica em uma adolescente com ventrículo único submetida à intervenção fisioterapêutica: relato de caso / Autonomic activity in an adolescent with a single ventricle who underwent physical therapy intervention: case report

OBJETIVO: Avaliar a atividade autonômica de uma adolescente com ventrículo único (VU), sem correção cirúrgica, participante de um programa de fisioterapia. MATERIAIS E MÉTODOS: Paciente do sexo feminino, 14 anos, com diagnóstico de VU tipo esquerdo, sem correção cirúrgica. A atividade autonômica foi avaliada pela variabilidade da freqüência cardíaca (VFC) nas posições supina e sentada, e pela manobra para acentuar a arritmia sinusal respiratória (M-ASR) no início do primeiro (A1), segundo (A2) e terceiro anos (A3) de tratamento fisioterapêutico cardiovascular (TFC) ambulatorial. Os intervalos RR e a freqüência cardíaca batimento a batimento foram calculados e armazenados para posterior análise. A VFC foi avaliada pelos índices RMSSD e RMSM e no domínio da freqüência pelas bandas de alta e baixa freqüência em unidades normalizadas (AFun e BFun, respectivamente) e pela razão BF/AF. O TFC constou de exercícios respiratórios associados a exercícios ativos e resistidos gerais, durante dois anos. RESULTADOS: De A1 para A3, o RMSM reduziu (14,5 por cento), a banda de BFun (42,2 por cento) e a razão BF/AF aumentou (117,0 por cento), e a banda AFun diminuiu (35,2 por cento). Em todas as situações, a banda BFun foi maior e a AFun foi menor na posição sentada. Além disso, a resposta parassimpática à M-ASR aumentou da situação A1 para A3 em 7,4 e 47,3 por cento, respectivamente. CONCLUSÕES: Concluímos que, na paciente estudada, a redução da VFC parece estar associada com o avanço da doença, porém, não houve prejuízos frente à mudança postural. Adicionalmente, o TFC proposto incrementou a resposta parassimpática durante a M-ASR.

OBJECTIVE: To evaluate the autonomic activity of an adolescent with a single ventricle without surgical correction who participated in a physical therapy program. METHODS: This was a 14-year-old female patient with a left-type single ventricle who had not undergone any surgical intervention. The autonomic activity was evaluated according to the heart rate variability in the supine and seated positions and by means of the respiratory sinus arrhythmia accentuation maneuver (RSA-M) in the beginning of the first, second and third years of outpatient cardiovascular physical therapy treatment. The RR intervals and beat-to-beat heart rate were calculated and stored for subsequent analysis. The heart rate variability was evaluated by means of the RMSSD and RMSM indexes and in the frequency domain with high and low frequency bands in normalized units (HFnu and LFnu, respectively) and using the LF/HF ratio. The cardiovascular physical therapy consisted of respiratory exercises associated with active and general resistance exercises, for two years. RESULTS: From the first to the third year, the RMSM decreased (14.5 percent), LFnu band increased (42.2 percent), LF/HF ratio increased (117.0 percent) and HFnu decreased (35.2 percent). In all of the situations, the LFnu band was higher and HFnu was lower in the seated position. Additionally, the parasympathetic response to RSA-M increased from the first to the third years in 7.4 percent and 47.3 percent, respectively. CONCLUSIONS: We concluded that, for the patient studied, the reduction in heart rate variability seemed to be associated with the advance of the disease. Nevertheless, there was no damages related to postural change. In addition, the cardiovascular physical therapy proposed increased the parasympathetic response during RSA-M.

Eficácia da intervenção fisioterapêutica associada ou não à respiração por pressão positiva intermitente (RPPI) após cirurgia cardíaca com circulação extracorpórea / Efficacy of physiotherapy intervention associated to intermitent posiitive pressure breathing after cardiac surgery with cardiopulmonary bypass

Este artigo objetivou avaliar as alterações na função pulmonar (FP) e força muscular respiratória (FMR)e eficácia de dois protocolos distintos em pacientes submetidos à cirurgia cardíaca (CC) com circulação extracorpórea (CEC). Método: 21 pacientes foram divididos em: GPPI (n=8), realizaram exercícios respiratórios com RPPI, associados à intervenção fisioterapêutica (IF); e GIF (n=13) realizaram somente IF. A FP foi avaliada pela espirometria no pré e 5º pós-operatório (PO) e a FMR pelas pressões respiratórias máximas (PImax e PEmax) no pré, 1º e 5º PO. O teste de Wilcoxon, Friedman e Man-Whitney foram utilizados para comparãções intra e intergrupos, respectivamente. Resultados: não foram observadas diferenças significativas nos parâmetros antropométricos, aspectos clínicos e cirúrgicos entre os grupos. Foram encontrados valores significativamente menores no 5º PO em comparação à situação pré-operatória no GIF para a capacidade vital (CV), capacidade vital forçada (CVF), volume expiratório forçado no 1º segundo (VEF1), pico de fluxo (PF) e fluxo expiratório forçado (PEF). No entanto, para GPPI apenas o VEF1 permaneceu significativamente reduzido após a intervenção (p<0,05). Para a PImax e PEmax observou-se redução do pré-operatório para o 1º PO em ambos os grupos. Porém, apenas a PEmax atingiu valores próximos aos dos pré-operatório até o 5ºPO em ambos os grupos, enquanto a PImax permaneceu significativamente reduzida no GIF. Na análise intergrupos não foram observadas diferenças significativas para nenhuma das variáveis analisadas. Conclusões: concluímos que pacientes submetidos à CC com CEC sofrem prejuízos na FP e FMR, e que nenhum dostratamentos aplicados (IF ou IF+RPPI) mostrou significante superioridade com relação ao outro.

A influencia das tecnicas de intervencao fisioterapeutica e da pressao positiva continua nas vias aereas (CPAP) no pos-operatorio de cirurgia cardiaca / The influence of physical therapy intervention techniques and continuos positive airway pressure (CPAP) following cardiac surgery

A cirurgia cardiaca (CC) leva a importantes alteracoes na funcao pulmonar, sendo necessario oferecer recursos fisioterapeuticos eficazes a esses pacientes. Objetivos: avalair o comportamento da funcao pulmonar, da forca muscular inspiratoria (FMI) e da mobilidade toraco-abdominal (MTA) em dois protocolos distintos de intervencao em pacientes submetidos a CC. Metodologia: dezeseis pacientes (57+-11 anos) foram divididos aleatoriamente em 2 grupos: grupo CPAP (GCP; n=8), querealizaram 30 minutos de pressao positiva continua nas vias aereas (CPAP) com niveis pressoricos de 7 a 10 cmH2O, e grupo intervencao fisioterapeutica (GIF; n=8). Foram avaliados a capacidade vital (CV), a capacidade vital forcada (CVF), o volume expiratorio forcado no primeiro segundo (VEF1), o fluxo expiratorio forcado (FEF 25-75 por cento), o pico de fluxo expiratorio (PF) e a FMI no pre-operatorio, primeiro e quinto PO e MTA no pre-operatorio e quinto PO. Resultados: constatou-se reducoes significativas de (VEF1, FEF25-75 por cento), PF e FMI em ambos os grupos tratados, quando comparado pre-operatorio com primeiro PO. Para a CV, apenas GIF apresentou reducoes do pre-operatorio para primeiro PO(p<0,001). Analisando o retorno das variaveis do quinto PO aos valores ppre-operatorios, somente a FMI nao reverteu os valores no GIF, bem como o (FEF 25-75 por cento) nao retornou no GCP. Em relacao a MTA, foi constatada reducao significativa em ambos os grupos apenas para os niveis axilares (p<0,05). Entretanto, nao foram encontradas diferencas entre os gruos (Mann-Whitney test). Conclusoes: A CC produz alteracoes importantes da funcao pulmonar, FMI e MTA, sendo que tanto a aplicacao da CPAP como a intervencao fisioterapeutica podem levar a reversao ate a alta hospitalar

Comprometimento cardíaco na amiloidose sistêmica. Diagnóstico in vivo / Heart disease and systemic amyloidosis. In vivo diagnosis

Descrevemos o caso de um paciente masculino de 42 anos, com amiloidose sistêmica, provavelmente primária, comprometendo o coraçäo. Ressaltam-se os aspectos fisiopatológicos, clínicos e a relativa raridade do diagnoóstico in vivo. Discutem-se, ainda que limitados, os aspectos terapêuticos relacionados aos problemas cardíacos.