Hareld M. C. Kemps

Evaluation of two methods for continuous cardiac output assessment during exercise in chronic heart failure patients.

The purpose of this study was to evaluate the accuracy of two techniques for the continuous assessment of cardiac output in patients with chronic heart failure (CHF): a radial artery pulse contour analysis method that uses an indicator dilution method for calibration (LiDCO) and an impedance cardiography technique (Physioflow), using the Fick method as a reference. Ten male CHF patients (New York Heart Association class II-III) were included. At rest, cardiac output values obtained by LiDCO and Physioflow were compared with those of the direct Fick method. During exercise, the continuous Fick method was used as a reference. Exercise, performed on a cycle ergometer in upright position, consisted of two constant-load tests at 30% and 80% of the ventilatory threshold and a symptom-limited maximal test. Both at rest and during exercise LiDCO showed good agreement with reference values [bias +/- limits of agreement (LOA), -1% +/- 28% and 2% +/- 28%, respectively]. In contrast, Physioflow overestimated reference values both at rest and during exercise (bias +/- LOA, 48% +/- 60% and 48% +/- 52%, respectively). Exercise-related within-patient changes of cardiac output, expressed as a percent change, showed for both techniques clinically acceptable agreement with reference values (bias +/- LOA: 2% +/- 26% for LiDCO, and -2% +/- 36% for Physioflow, respectively). In conclusion, although the limits of agreement with the Fick method are pretty broad, LiDCO provides accurate measurements of cardiac output during rest and exercise in CHF patients. Although Physioflow overestimates cardiac output, this method may still be useful to estimate relative changes during exercise.

Cardiac rehabilitation and survival in a large representative community cohort of Dutch patients.

AIMS To assess the effects of multi-disciplinary cardiac rehabilitation (CR) on survival in the full population of patients with an acute coronary syndrome (ACS) and patients that underwent coronary revascularization and/or heart valve surgery. METHODS AND RESULTS Population-based cohort study in the Netherlands using insurance claims database covering ∼22% of the Dutch population (3.3 million persons). All patients with an ACS with or without ST elevation, and patients who underwent coronary revascularization and/or valve surgery in the period 2007-10 were included. Patients were categorized as having received CR when an insurance claim for CR was made within the first 180 days after the cardiac event or revascularization. The primary outcome was survival time from the inclusion date, limited to a total follow-up period of 4 years, with a minimum of 180 days. Propensity score weighting was used to control for confounding by indication. Among 35 919 patients with an ACS and/or coronary revascularization or valve surgery, 11 014 (30.7%) received CR. After propensity score weighting, the adjusted hazard ratio (HR) associated with receiving CR was 0.65 (95% CI 0.56-0.77). The largest benefit was observed for patients who underwent coronary artery bypass grafting (CABG) and/or valve surgery (HR = 0.55, 95% CI 0.42-0.74). CONCLUSION In a large and representative community cohort of Dutch patients with an ACS and/or intervention, CR was associated with a substantial survival benefit up to 4 years. This survival benefit was present regardless of age, type of diagnosis, and type of intervention.

Cardiac rehabilitation uptake and its determinants in the Netherlands.

Aims: Despite its documented efficacy, cardiac rehabilitation (CR) is still not well implemented in current clinical practice. The aims of the present study were to assess CR uptake rates in the Netherlands, and to identify factors that determine uptake. Methods: The cohort consisted of persons insured with Achmea Zorg en Gezondheid. Based on insurance claims, we assessed CR uptake rates in 2007 among patients with an acute coronary syndrome (ACS), patients who underwent coronary artery bypass graft surgery, percutaneous coronary intervention (PCI), or valvular surgery, and patients with stable angina pectoris (AP) or chronic heart failure (CHF). In addition, we evaluated the relation between CR uptake and demographic, disease-related, and geographic factors for patients with an ACS and/or intervention. Results: The CR uptake rate in the entire cohort (n = 35,752) was 11.7%. The uptake rate among patients with an ACS and/or intervention (n = 12,201) was 28.5%, as opposed to 3.0% among patients with CHF or stable AP (n = 23,551). The highest CR uptake rate was observed in patients who underwent cardiac surgery (58.7%). Factors associated with lower CR uptake were female gender, older age, elective PCI (as compared to acute PCI), unstable AP (as compared to myocardial infarction), larger distance to the nearest provider of CR, and comorbidity. Conclusion: A minority of Dutch patients eligible for CR received CR. Future implementation strategies should focus on females, elderly patients, patients with unstable AP and/or after elective PCI, patients with long travelling distances to the nearest CR provider, and patients with comorbidities.

Exercise-based cardiac rehabilitation in patients with coronary heart disease: a practice guideline

BackgroundTo improve the quality of exercise-based cardiac rehabilitation (CR) in patients with coronary heart disease (CHD) the CR guideline from the Dutch Royal Society for Physiotherapists (KNGF) has been updated. This guideline can be considered an addition to the 2011 Dutch Multidisciplinary CR guideline, as it includes several novel topics.MethodsA systematic literature search was performed to formulate conclusions on the efficacy of exercise-based interventions during all CR phases in patients with CHD. Evidence was graded (1–4) according the Dutch evidence-based guideline development (EBRO) criteria. In case of insufficient scientific evidence, recommendations were based on expert opinion. This guideline comprised a structured approach including assessment, treatment and evaluation.ResultsRecommendations for exercise-based CR were formulated covering the following topics: preoperative physiotherapy, mobilisation during the clinical phase, aerobic exercise, strength training, and relaxation therapy during the outpatient rehabilitation phase, and adoption and monitoring of a physically active lifestyle after outpatient rehabilitation.ConclusionsThere is strong evidence for the effectiveness of exercise-based CR during all phases of CR. The implementation of this guideline in clinical practice needs further evaluation as well as the maintenance of an active lifestyle after supervised rehabilitation.

Skeletal muscle metabolic recovery following submaximal exercise in chronic heart failure is limited more by O2 delivery than O2 utilization

CHF (chronic heart failure) is associated with a prolonged recovery of skeletal muscle energy stores following submaximal exercise, limiting the ability to perform repetitive daily activities.However, the pathophysiological background of this impairment is not well established. The aim of the present study was to investigate whether muscle metabolic recovery following submaximal exercise in patients with CHF is limited by O2 delivery or O2 utilization. A total of 13 stable CHF patients (New York Heart Association classes II-III) and eight healthy subjects, matched for age and BMI (body mass index), were included. All subjects performed repetitive submaximal dynamic single leg extensions in the supine position. Post-exercise PCr (phosphocreatine) resynthesis was assessed by 31P-MRS (magnetic resonance spectroscopy). NIRS (near-IR spectroscopy) was applied simultaneously, using the rate of decrease in HHb (deoxygenated haemoglobin) as an index of post-exercise muscle re-oxygenation. As expected, PCr recovery was slower in CHF patients than in control subjects (time constant, 47+/-10 compared with 35+/-12 s respectively; P=0.04). HHb recovery kinetics were also prolonged in CHF patients (mean response time, 74+/-41 compared with 44+/-17 s respectively; P=0.04). In the patient group, HHb recovery kinetics were slower than PCr recovery kinetics (P=0.02), whereas no difference existed in the control group(P=0.32). In conclusion, prolonged metabolic recovery in CHF patients is associated with an even slower muscle tissue re-oxygenation, indicating a lower O(2) delivery relative to metabolic demands. Therefore we postulate that the impaired ability to perform repetitive daily activities in these patients depends more on a reduced muscle blood flow than on limitations in O(2) utilization.

Are oxygen uptake kinetics in chronic heart failure limited by oxygen delivery or oxygen utilization

BACKGROUND The delay in O(2) uptake kinetics during and after submaximal physical activity (O(2) onset and recovery kinetics, respectively) correlates well with the functional capacity of patients with chronic heart failure (CHF). This study examined the physiological background of this delay in moderately impaired CHF patients by comparing kinetics of cardiac output (Q) and O(2) uptake (V(O(2))). METHODS Fourteen stable CHF patients (New York Heart Association class II-III) and 8 healthy subjects, matched for age and body mass index, were included. All subjects performed a submaximal constant-load exercise test to assess O(2) uptake kinetics. Furthermore, in 10 CHF patients Q was measured by a radial artery pulse contour analysis method, which enabled the simultaneous modelling of exercise-related kinetics of Q and V(O(2)). RESULTS Both O(2) onset and recovery kinetics were delayed in the patient group. There were no significant differences between the time constants of Q and V(O(2)) during exercise-onset (62+/-25 s versus 59+/-28 s, p=0.51) or recovery (61+/-25 s versus 57+/-20 s, p=0.38) in the patient group, indicating that O(2) delivery was not in excess of the metabolic demands in these patients. CONCLUSION The delay in O(2) onset and recovery kinetics in moderately impaired CHF patients is suggested to be due to limitations in O(2) delivery. Therefore, strategies aimed at improving exercise performance of these patients should focus more on improvements of O(2) delivery than on O(2) utilization.

Predicting Effects of Exercise Training in Patients With Heart Failure Secondary to Ischemic or Idiopathic Dilated Cardiomyopathy

The purpose of this study was to investigate which patient characteristics may predict training effects on maximal and submaximal exercise performance in patients with heart failure. Together with commonly used clinical and performance-related variables, oxygen uptake kinetics during exercise recovery were included as possible predictors. Fifty patients with heart failure (New York Heart Association class II or III) performed a 12-week training program (cycle interval and resistance training). Training effects were expressed as changes in peak oxygen uptake (Vo(2)), Vo(2) at ventilatory threshold (VT), and the time constant of Vo(2) recovery after submaximal exercise (tau-rec). After training, peak Vo(2), Vo(2) at VT, and tau-rec improved significantly, with a wide variety in training responses. Changes in peak Vo(2) were related to changes in VT (r = 0.79, p <0.001), but both changes were not related to changes in tau-rec. Using multivariate regression analyses, post-training changes in peak Vo(2) could be predicted by recovery halftime of peak Vo(2) (T1/2), peak Vo(2) (percentage of predicted), and peak respiratory exchange ratio (R(2) = 36%). Post-training changes in VT could be predicted by T1/2 and VT (predicted) (R(2) = 29%), whereas changes in tau-rec could be predicted only by tau-rec at baseline (R(2) = 34%). In conclusion, oxygen recovery kinetics after maximal and submaximal exercise substantially add to the prediction of training effects in patients with heart failure, presumably because of their relations with, respectively, central and peripheral impairments of exercise capacity. However, the explained variance in training effects is not sufficient to make a definite distinction between training responders and nonresponders.

Effects of home-based training with telemonitoring guidance in low to moderate risk patients entering cardiac rehabilitation: short-term results of the FIT@Home study

Background Home-based exercise training in cardiac rehabilitation (CR) has the potential to improve CR uptake, decrease costs and increase self-management skills. The FIT@Home study evaluates home-based CR with telemonitoring guidance using coaching interventions including strategies for behavioural changes with the aim to maintain adherence to a healthy lifestyle and to improve long-term effects. In this interim analysis we provide short-term results on exercise capacity, quality of life and training adherence of the first 50 patients included in the FIT@Home study. Design The study design was a randomised controlled trial. Methods Low to moderate risk CR patients were randomised to a 12-week home-based training (HT) programme or a 12-week centre-based training (CT) programme. In both groups, training was performed at 70–85% of maximal heart rate (HRmax) for 45–60 min, 2–3 times per week. The HT group received three supervised training sessions, before commencing training with a heart rate monitor in their home environment. These patients received individual coaching by telephone weekly, based on training data uploaded on the Internet. The CT programme was performed under the direct supervision of a physical therapist. Exercise capacity and health-related quality of life were assessed at baseline and at 12 weeks. Results CT (n = 25) and HT (n = 25) both showed a significant improvement in peak oxygen uptake (peak VO2) (10% and 14% respectively) and quality of life after 12 weeks of training, without significant between-group differences. The average training intensity of the HT group was 73.3 ± 3.5% of HRmax. Training adherence was similar between groups. Conclusion This analysis shows that HT with telemonitoring guidance has similar short-term effects on exercise capacity and quality of life as CT in CR patients.

The influence of training characteristics on the effect of aerobic exercise training in patients with chronic heart failure: A meta-regression analysis

Although aerobic exercise training has shown to be an effective treatment for chronic heart failure patients, there has been a debate about the design of training programs and which training characteristics are the strongest determinants of improvement in exercise capacity. Therefore, we performed a meta-regression analysis to determine a ranking of the individual effect of the training characteristics on the improvement in exercise capacity of an aerobic exercise training program in chronic heart failure patients. We focused on four training characteristics; session frequency, session duration, training intensity and program length, and their product; total energy expenditure. A systematic literature search was performed for randomized controlled trials comparing continuous aerobic exercise training with usual care. Seventeen unique articles were included in our analysis. Total energy expenditure appeared the only training characteristic with a significant effect on improvement in exercise capacity. However, the results were strongly dominated by one trial (HF-action trial), accounting for 90% of the total patient population and showing controversial results compared to other studies. A repeated analysis excluding the HF-action trial confirmed that the increase in exercise capacity is primarily determined by total energy expenditure, followed by session frequency, session duration and session intensity. These results suggest that the design of a training program requires high total energy expenditure as a main goal. Increases in training frequency and session duration appear to yield the largest improvement in exercise capacity.

Improving guideline adherence for cardiac rehabilitation in the Netherlands

BackgroundIn 2004, the Netherlands Society of Cardiology released the current guideline on cardiac rehabilitation. Given its complexity and the involvement of various healthcare disciplines, it was supplemented with a clinical algorithm, serving to facilitate its implementation in daily practice. Although the algorithm was shown to be effective for improving guideline adherence, several shortcomings and deficiencies were revealed. Based on these findings, the clinical algorithm has now been updated. This article describes the process and the changes that were made.MethodsThe revision consisted of three phases. First, the reliability of the measurement instruments included in the 2004 Clinical Algorithm was investigated by evaluating between-centre variations of the baseline assessment data. Second, based on the available evidence, a multidisciplinary expert advisory panel selected items needing revision and provided specific recommendations. Third, a guideline development group decided which revisions were finally included, also taking practical considerations into account.ResultsA total of nine items were revised: three because of new scientific insights and six because of the need for more objective measurement instruments. In all revised items, subjective assessment methods were replaced by more objective assessment tools (e.g. symptom-limited exercise instead of clinical judgement). In addition, four new key items were added: screening for anxiety/depression, stress, cardiovascular risk profile and alcohol consumption.ConclusionBased on previously determined shortcomings, the Clinical Algorithm for Cardiac Rehabilitation was thoroughly revised mainly by incorporating more objective assessment methods and by adding several new key areas.