Impact of cardiac rehabilitation on ventricular-arterial coupling and left ventricular function in patients with acute myocardial infarction.

To maintain efficient myocardial function, optimal coordination between ventricular contraction and the arterial system is required. Exercise-based cardiac rehabilitation (CR) has been demonstrated to improve left ventricular (LV) function. This study aimed to investigate the impact of CR on ventricular-arterial coupling (VAC) and its components, as well as their associations with changes in LV function in patients with acute myocardial infarction (AMI) and preserved or mildly reduced ejection fraction (EF). Effective arterial elastance (EA) and index (EAI) were calculated from the stroke volume and brachial systolic blood pressure. Effective LV end-systolic elastance (ELV) and index (ELVI) were obtained using the single-beat method. The characteristic impedance (Zc) of the aortic root was calculated after Fourier transformation of both aortic pressure and flow waveforms. Pulse wave separation analysis was performed to obtain the reflection magnitude (RM). An exercise-based, outpatient cardiac rehabilitation (CR) program was administered for up to 6 months. Twenty-nine patients were studied. However, eight patients declined to participate in the CR program and were subsequently classified as the non-CR group. At baseline, E' velocity showed significant associations with EAI (beta -0.393; P = 0.027) and VAC (beta -0.375; P = 0.037). There were also significant associations of LV global longitudinal strain (LV GLS) with EAI (beta 0.467; P = 0.011). Follow-up studies after a minimum of 6 months demonstrated a significant increase in E' velocity (P = 0.035), improved EF (P = 0.010), and LV GLS (P = 0.001), and a decreased EAI (P = 0.025) only in the CR group. Changes in E' velocity were significantly associated with changes in EAI (beta -0.424; P = 0.033). Increased aortic afterload and VA mismatch were associated with a negative impact on both LV diastolic and systolic function. The outpatient CR program effectively decreased aortic afterload and improved LV diastolic and systolic dysfunction in patients with AMI and preserved or mildly reduced EF.

Significance of Cycle Ergometer as a Measure of Peak Aerobic Capacity in the Disabled.

BACKGROUND: To compare different physiological responses between treadmill and cycle ergometer in stroke patients in regard to community ambulation, and to determine strong predictors of equipment-dependent VO2peak and its related factors among physical fitness parameters and finally to establish the significance of cycle ergometer as a measure of VO2peak in the disabled according to gait function. METHODS: Sixty-three stroke survivors were enrolled in this study and were grouped according to the gait speed (32 non-community ambulators <0.8 m/s:31 community ambulators ≥0.8 m/s). All participants performed exercise stress test (EST) with treadmill and cycle ergometer and rehabilitation function tests. RESULTS: Community ambulators achieved higher VO2peak by treadmill, but non-community ambulators showed similar VO2peak between treadmill and cycle ergometer due to gait problems. The gait speed and endurance were strong predictors of difference of peak aerobic capacity between treadmill and cycle ergometer (multiple regression analysis, adjusted R2=0.458). CONCLUSION: Cycle ergometer might be more appropriate for non-community ambulatory stroke patients to assess the peak aerobic capacity. Gait speed and gait distance could affect equipment-dependent cardiopulmonary performance significantly in the disabled. Therefore, the careful consideration of comprehensive and objective physical function including gait endurance, and speed and prescription of appropriate exercise intensity and equipment depending on the severity should be needed to improve the cardiopulmonary fitness and physical function adequately in stroke rehabilitation.

Hemiparetic Knee Extensor Strength and Balance Function Are Predictors of Ambulatory Function in Subacute Stroke Patients.

OBJECTIVE: To identify the potential predictors of ambulatory function in subacute stroke patients, and to determine the contributing factors according to gait severity. METHODS: Fifty-three subacute stroke patents were enrolled. Ambulatory function was assessed by gait speed and endurance. Balance function was evaluated by the Berg Balance Scale score (BBS) and the Timed Up and Go test (TUG). The isometric muscular strengths of bilateral knee extensors and flexors were measured using an isokinetic dynamometer. Cardiovascular fitness was evaluated using an expired gas analyzer. Participants were assigned into the household ambulator group (<0.4 m/s) or the community ambulator group (≥0.4 m/s) based on gait severity. RESULTS: In the linear regression analyses of all patients, paretic knee isometric extensor strength (p=0.007) and BBS (p<0.001) were independent predictors of gait endurance (R(2)=0.668). TUG (p<0.001) and BBS (p=0.037) were independent predictors of gait speed (R(2)=0.671). Paretic isometric extensor strength was a predictor of gait endurance (R(2)=0.340, p=0.008). TUG was a predictor of gait speed (R(2)=0.404, p<0.001) in the household ambulator group, whereas BBS was a predictive factor of gait endurance (R(2)=0.598, p=0.008) and speed (R(2)=0.713, p=0.006). TUG was a predictor of gait speed (R(2)=0.713, p=0.004) in the community ambulator group. CONCLUSION: Our results reveal that balance function and knee extensor isometric strength were strong predictors of ambulatory function in subacute stroke patients. However, they work differently according to gait severity. Therefore, a comprehensive functional assessment and a different therapeutic approach should be provided depending on gait severity in subacute stroke patients.

Comparison of cardiorespiratory responses during aquatic and land treadmill exercise in patients with coronary artery disease.

PURPOSE: To investigate cardiorespiratory responses during exercise stress tests using an aquatic treadmill and a land-based treadmill in patients with coronary artery disease (CAD). METHODS: Twenty-one stable CAD patients were enrolled. All patients participated in 2 symptom-limited incremental exercise tests, using both an aquatic and a land treadmill. For the aquatic treadmill protocol, patients were submerged to the upper waist in 28°C water. The treadmill speed started at 2.0 km/h and increased 0.5 km/h every minute thereafter. For the land treadmill protocol, the speed and gradient were started at 2.4 km/h and 1.5%, respectively. The speed was increased by 0.3 km/h and grade by 1% every minute thereafter. Oxygen consumption ((Equation is included in full-text article.)O2), heart rate (HR), and respiratory exchange ratio were measured continuously and peak values recorded. Rating of perceived exertion, percentage of age-predicted maximal HR, and total exercise duration were also recorded. RESULTS: Peak cardiorespiratory responses during both protocols were compared. The peak (Equation is included in full-text article.)O2 and peak HR did not show any significant differences. The peak respiratory exchange ratio was significantly greater using the land treadmill than the aquatic treadmill protocol. Rating of perceived exertion, age-predicted maximal HR percentage, and total exercise duration were similar for both protocols. There was a significant linear relationship between HR and (Equation is included in full-text article.)O2 with both protocols. CONCLUSIONS: This study demonstrated that aquatic treadmill exercise elicits similar peak cardiorespiratory responses compared with land treadmill exercise, suggesting that aquatic treadmill exercise may be effective for CAD patients in cardiac rehabilitation.

Cardiovascular fitness as a predictor of functional recovery in subacute stroke patients.

PURPOSE: To investigate the correlation between baseline cardiovascular fitness and functional status, and whether baseline cardiovascular fitness is of predictive value in terms of functional recovery after rehabilitation in subacute stroke patients. METHOD: This study was a descriptive, observational cohort study. Fifty-five subacute stroke patients (37 males and 18 females; average age, 62.2 years) were enrolled for this study, and all subjects underwent symptom-limited low-velocity graded treadmill testing. Baseline assessments included cardiovascular fitness, 6-min walk test (6MWT), Korean-Modified Barthel Index (K-MBI) and Motricity Index (MI). Four weeks after rehabilitation, K-MBI was measured repeatedly. RESULTS: Mean peak oxygen consumption (Vo2 peak) was 19.7 ± 6.7 mL/kg/min. Baseline K-MBI correlated significantly with Vo2 peak, peak heart rate (HR), 6MWT and MI, and in regression analysis, Vo2 peak and MI were significant independent predictors of baseline K-MBI. Follow-up K-MBI correlated significantly with Vo2 peak, peak HR, peak rate pressure product, 6MWT, baseline K-MBI and MI, and in linear regression analysis, Vo2 peak and baseline K-MBI were significant independent predictors of follow-up K-MBI. CONCLUSION: These results indicate that baseline cardiovascular fitness correlates significantly with the baseline functional status, in addition to being an important prognostic factor regarding the functional recovery of subacute stroke patients.

The effects of assisted ergometer training with a functional electrical stimulation on exercise capacity and functional ability in subacute stroke patients.

OBJECTIVE: To determine if assistive ergometer training can improve the functional ability and aerobic capacity of subacute stroke patients and if functional electrical stimulation (FES) of the paretic leg during ergometer cycling has additional effects. METHODS: Sixteen subacute stroke patents were randomly assigned to the FES group (n=8) or the control group (n=8). All patients underwent assistive ergometer training for 30 minutes (five times per week for 4 weeks). The electrical stimulation group received FES of the paretic lower limb muscles during assistive ergometer training. The six-minute walk test (6MWT), Berg Balance Scale (BBS), and the Korean version of Modified Barthel Index (K-MBI) were evaluated at the beginning and end of treatment. Peak oxygen consumption (Vo2peak), metabolic equivalent (MET), resting and maximal heart rate, resting and maximal blood pressure, maximal rate pressure product, submaximal rate pressure product, submaximal rate of perceived exertion, exercise duration, respiratory exchange ratio, and estimated anaerobic threshold (AT) were determined with the exercise tolerance test before and after treatment. RESULTS: At 4 weeks after treatment, the FES assistive ergometer training group showed significant improvements in 6MWT (p=0.01), BBS (p=0.01), K-MBI (p=0.01), Vo2peak (p=0.02), MET (p=0.02), and estimated AT (p=0.02). The control group showed improvements in only BBS (p=0.01) and K-MBI (p=0.02). However, there was no significant difference in exercise capacity and functional ability between the two groups. CONCLUSION: This study demonstrated that ergometer training for 4 weeks improved the functional ability of subacute stroke patients. In addition, aerobic capacity was improved after assisted ergometer training with a FES only.

Interleukin-6 but not tumour necrosis factor-alpha predicts survival in patients with advanced cancer.

PURPOSE: The purpose of this study was to evaluate the prognostic role of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) in the survival of patients with advanced cancer. METHODS: In this prospective cohort study between three hospice and palliative care centres in South Korea, we followed 98 advanced cancer patients until death or the end of the study. Approximately 60 % of the patients had poor functional status (Eastern Cooperative Oncology Group score ≥3). We investigated the symptoms of cancer cachexia anorexia syndrome, possible cytokine-related confounders such as infection and medication records. Influence from clinical variables was adjusted using the Cox proportional hazard model. RESULTS: The median survival time was 27 days. On multivariate analysis, elevated IL-6 (hazard ratio, 2.139; p = 0.003) was found to be an independent significant prognostic factor. TNF-α was not a significant factor. Poor performance status and male gender were also independently related to shortened survival. CONCLUSIONS: IL-6 level can be a useful indicator of survival time of patients with advanced cancer at the very end of life. In contrast, the prognostic role of TNF-α requires further study.

The relationship between interleukin-6, tumor necrosis factor-α, and fatigue in terminally ill cancer patients.

Although many cancer patients receiving palliative care experience distressing levels of fatigue, no well-designed studies have investigated contributing factors in Korean patients. We conducted a cross-sectional study using the Brief Fatigue Inventory-K (BFI-K) to measure fatigue while assessing a variety of possible correlates. Ninety patients with incurable cancer in the terminal stage (median survival: 27 days) participated in a structured interview and questionnaire related to their medical conditions and underwent blood sampling for laboratory data and cytokines, including interleukin (IL)-6 and tumor necrosis factor (TNF)-α. Body mass index, dyspnea, the Eastern Cooperative Oncology Group performance status, and levels of albumin, blood urea nitrogen (BUN), total bilirubin, and C-reactive protein were significantly associated with fatigue. However, levels of the two proinflammatory cytokines, IL-6 and TNF-α, were not significantly correlated with the BFI-K score. In stepwise multiple linear regression, fatigue was related to elevated BUN (ß = 0.376, p = 0.002), severe pain intensity (ß = 0.349, p = 0.004), and impaired performance status (ß = 0.268, p = 0.027), but not related to levels of inflammatory cytokines. In conclusion, the diagnostic work-up and therapeutic plan for patients with cancer-related fatigue should include an evaluation of laboratory parameters, pain severity, and physical performance.