Does recovery from submaximal exercise predict response to cardiac resynchronisation therapy?

BACKGROUND: Exercise parameters are not routinely incorporated in decision making for cardiac resynchronisation therapy (CRT). Submaximal exercise parameters better reflect daily functional capacity of heart failure patients than parameters measured at maximal exertion, and may therefore better predict response to CRT. We compared various exercise parameters, and sought to establish which best predict CRT response. METHODS: In 31 patients with chronic heart failure (61% male; age 68±7 years), submaximal and maximal cycling testing was performed before and 3 months after CRT. Submaximal oxygen onset (τVO(2) onset) and recovery kinetics (τVO(2) recovery), peak oxygen uptake (VO(2) peak) and oxygen uptake efficiency slope (OUES) where measured. Response was defined as ≥15% relative reduction in end-systolic volume. RESULTS: After controlling for age, New York Heart Association and VO(2) peak, fast submaximal VO(2) kinetics were significantly associated with response to CRT, measured either during onset or recovery of submaximal exercise (area under the curve, AUC=0.719 for both; p<0.05). By contrast, VO(2) peak (AUC=0.632; p=0.199) and OUES (AUC=0.577; p=0.469) were not associated with response. Among patients with fast onset and recovery kinetics, below 60 s, a significantly higher percentage of responders was observed (91% and 92% vs 43% and 40%, respectively). CONCLUSIONS: Impaired VO(2) kinetics may serve as an objective marker of submaximal exercise capacity that is age-independently associated with non-response following CRT, whereas maximal exercise parameters are not. Assessment of VO(2) kinetics is feasible and easy to perform, but larger studies should confirm their clinical utility

O2 Pulse Patterns in Male Master Athletes with Normal and Abnormal Exercise Tests

PURPOSE: The clinical relevance of abnormal exercise testing (ET) results (at least 0.1 mV ST segment depression measured during exercise or recovery in three consecutive beats) in athletes without obstructive coronary artery disease (CAD) is not well understood. It is unknown whether this phenomenon reflects a physiological adaptation to sport or a truly ischemic response and a concomitant attenuated stroke volume (SV) response. The aim of this study was to investigate if athletes with abnormal ET results without obstructive CAD showed signs of an attenuated SV response using cardiopulmonary ET parameters. METHODS: A total of 78 male master athletes with abnormal ET results without obstructive CAD underwent cardiopulmonary ET. ΔO2 pulse/Δwork rate (WR), ΔV˙O2/ΔWR, and Δheart rate (HR)/ΔWR were assessed and compared with data from 78 male master athletes with normal ET results, matched for age, sports characteristics, and exercise capacity. RESULTS: The ΔO2 pulse/ΔWR ratio beyond anaerobic threshold in athletes with abnormal ET results was lower than that in athletes with normal ET results (0.73 ± 0.41 vs 1.12 ± 0.54, respectively, P < 0.001). The ΔV˙O2/ΔWR ratio was also lower in athletes with abnormal ET results (0.9 ± 0.2 vs 1.0 ± 0.3, respectively, P = 0.041). Furthermore, these athletes showed a greater increase in HR in the last 2 min of exercise (ΔHR/ΔWR ratio: 1.19 ± 0.5 vs 0.80 ± 0.6, P < 0.001). CONCLUSION: Athletes with abnormal ET results without obstructive CAD showed an attenuated O2 pulse slope, decreased ΔV˙O2/ΔWR ratio, and increased ΔHR/ΔWR ratio beyond anaerobic threshold when compared with athletes with a normal ET result. These results support the hypothesis that at least a part of the athletes with an abnormal ET in absence of obstructive CAD have an attenuated SV response at high-intensity exercise

A demonstration of high field-of-view stability in hands-free echocardiography

Background: Exercise stress echocardiography is clinically used to assess cardiovascular diseases. For accurate cardiac evaluation, a stable field-of-view is required. However, transducer orientation and position are difficult to preserve. Hands-free acquisitions might provide more consistent and reproducible results. In this study, the field-of-view stability and variability of hands-free acquisitions are objectively quantified in a comparison with manually obtained images, based on image structural and feature similarities. In addition, the feasibility and consistency of hands-free strain imaging is assessed. Methods: In twelve healthy males, apical and parasternal images were acquired hands-free, using a fixation device, and manually, during semi-supine exercise sessions. In the final ten seconds of every exercise period, the image structural similarity and cardiac feature consistency were computed using a steerable pyramid employing complex, oriented wavelets. An algorithm discarding images displaying lung artifacts was created. Hands-free strain consistency was analyzed. Results: Hands-free acquisitions were possible in 9 of the 12 subjects, whereas manually 10 out of 12 could be imaged. The image structural similarity was significantly improved in the hands-free apical window acquisitions (0.91 versus 0.82), and at least equally good in the parasternal window (0.90 versus 0.82). The change in curvature and orientation of the interventricular septum also appeared to be lower in the hands-free acquisitions. The variability in field-of-view was similar in both acquisitions. Longitudinal, septal strain was shown to be at least as consistent when obtained hands-free compared to manual acquisitions. Conclusions: The field-of-view was shown to be more or equally stable and consistent in the hands-free data in comparison to manually obtained images. The variability was similar, thus respiration-and exercise-induced motions were comparable for manual and hands-free acquisitions. Additionally, the feasibility of hands-free strain has been demonstrated. Furthermore, the results suggest the hands-free measurements to be more reproducible, though further analysis is required

The relation between cardiac output kinetics and skeletal muscle oxygenation during moderate exercise in moderately impaired patients with chronic heart failure

Oxygen uptake (V̇O2) kinetics are prolonged in patients with chronic heart failure (CHF). This may be caused by impaired oxygen delivery or skeletal muscle derangements. We investigated whether impaired cardiac output (Q) kinetics limit skeletal muscle oxygen delivery relative to the metabolic demands at submaximal exercise in CHF patients by evaluating the relation between Q kinetics and skeletal muscle deoxygenation. Forty-three CHF patients, NYHA II-III, performed a constant-load exercise test at 80% of the VAT to assess V̇O2 kinetics (τVO2). Q kinetics (τQ) were assessed by a radial artery pulse contour analysis method. Skeletal muscle deoxygenation was assessed by near infrared spectroscopy at the m. vastus lateralis, using the minimal value of the tissue saturation index during onset of exercise (TSImin). Patients were categorized in slow and normal Q responders relative to metabolic demands (τQ/ V̇O2 ≥ 1 and τQ/ VO2 < 1, respectively) τQ (62 +/- 29s) and τV̇O2 (60+/-21s) were significantly related (r=0.66, p= 0.001). There was a significant correlation between τQ and TSImin in the slow Q responders (rs= -0.57, p=0.005, n=22 (51%)) In conclusion, in moderately impaired CHF patients with relatively slow Q kinetics, central hemodynamics may limit skeletal muscle oxygenation during moderate-intensity exercise

Image acquisition stability of fixated musculoskeletal sonography in an exercise setting: a quantitative analysis and comparison with freehand acquisition

Purpose: In dynamic musculoskeletal sonography, probe fixation can contribute to field of view (FOV) consistency, which is necessary for valid analysis of architectural parameters. In this volunteer study, the achieved FOV consistency in fixated ultrasonography was quantified and compared with freehand acquisition. Methods: During five resting periods during cycling exercise, longitudinal B-mode images of the vastus lateralis (VL) muscle were acquired on one thigh with a fixated probe, and by two trained observers on the other thigh. In each acquisition, the structural similarity compared to the first resting period was determined using the complex wavelet structural similarity index (CW-SSIM). Also, the pennation angle of the VL was measured. Both CW-SSIM and pennation angle were compared between fixated and freehand acquisition. Furthermore, the compression of tissue by the probe fixation was measured. Results: In fixated acquisition, a significantly higher structural similarity (p < 0.05) and an improved repeatability of pennation angle measurement were obtained compared to freehand acquisition. Probe fixation compressed muscle tissue by 12% on average. Conclusions: Quantification of the structural similarity showed an increase in FOV consistency with sonography compared to freehand acquisition. The demonstrated feasibility of long-term fixated acquisition might be attractive in many medical fields and sports, and for reduction of work-related ergonomic problems among sonographers

O2 Pulse Patterns in Male Master Athletes with Normal and Abnormal Exercise Tests

Purpose The clinical relevance of abnormal exercise testing (ET) results (at least 0.1 mV ST segment depression measured during exercise or recovery in three consecutive beats) in athletes without obstructive coronary artery disease (CAD) is not well understood. It is unknown whether this phenomenon reflects a physiological adaptation to sport or a truly ischemic response and a concomitant attenuated stroke volume (SV) response. The aim of this study was to investigate if athletes with abnormal ET results without obstructive CAD showed signs of an attenuated SV response using cardiopulmonary ET parameters. Methods A total of 78 male master athletes with abnormal ET results without obstructive CAD underwent cardiopulmonary ET. ΔO2 pulse/Δwork rate (WR), ΔVO2/ΔWR, and Δheart rate (HR)/ΔWR were assessed and compared with data from 78 male master athletes with normal ET results, matched for age, sports characteristics, and exercise capacity. Results The ΔO2 pulse/ΔWR ratio beyond anaerobic threshold in athletes with abnormal ET results was lower than that in athletes with normal ET results (0.73 ± 0.41 vs 1.12 ± 0.54, respectively, P < 0.001). The ΔVO2/ΔWR ratio was also lower in athletes with abnormal ET results (0.9 ± 0.2 vs 1.0 ± 0.3, respectively, P = 0.041). Furthermore, these athletes showed a greater increase in HR in the last 2 min of exercise (ΔHR/ΔWR ratio: 1.19 ± 0.5 vs 0.80 ± 0.6, P < 0.001). Conclusion Athletes with abnormal ET results without obstructive CAD showed an attenuated O2 pulse slope, decreased ΔVO2/ΔWR ratio, and increased ΔHR/ΔWR ratio beyond anaerobic threshold when compared with athletes with a normal ET result. These results support the hypothesis that at least a part of the athletes with an abnormal ET in absence of obstructive CAD have an attenuated SV response at high-intensity exercise

High intensity interval training after cardiac resynchronization therapy : An explorative randomized controlled trial

BACKGROUND: CRT leads to improvement in exercise capacity, cardiac function and mortality in selected CHF patients. Exercise capacity improves even greater when combining CRT with moderate-intensity exercise training (ET). However, high-intensity interval training (HIT) as additional therapy to CRT has not yet been established. Given the complementary physiological effects of HIT, we hypothesized that HIT after CRT may have additional effects on exercise capacity. METHODS: 24 CHF patients, NYHA class II/III and accepted for CRT underwent an echocardiogram, QoL questionnaire and CPET with cardiac output (CO) measurements before implantation, at 3 and 6 months. After 3 months, patients were randomized to usual care (UC) or HIT, consisting of 36 sessions at 85-95% of peak V̇O 2. RESULTS: Peak V̇O 2 increased after CRT (17±5.3 to 18.7±6.2 ml/kg/min, p < 0.05); after HIT there was a non-significant increase of 1.4 ml/kg/min (p = 0.12). Peak workload increased after CRT (109±45 to 118±44 W, p = 0.001). An additional significant within- and between group increase after HIT was found in the intervention group (128±42 to 148±48 W, versus 110±50 to 110±50, respectively, p = 0.03). Peak CO did not change significantly after CRT or HIT. V̇O 2 recovery kinetics speeded by 27% after CRT (p = 0.04), no further improvement after HIT was observed. LVEF increased 25% after CRT (p = 0.0001), no additional increase was seen after HIT. CONCLUSION: This study demonstrates that HIT provides additional improvement of exercise capacity without a concomitant change in peak V̇O 2 or CO suggesting that the additional effect of HIT is mainly mediated by an improvement of anaerobic performance

High intensity interval training after cardiac resynchronization therapy: An explorative randomized controlled trial

Background: CRT leads to improvement in exercise capacity, cardiac function and mortality in selected CHF patients. Exercise capacity improves even greater when combining CRT with moderate-intensity exercise training (ET). However, high-intensity interval training (HIT) as additional therapy to CRT has not yet been established. Given the complementary physiological effects of HIT, we hypothesized that HIT after CRT may have additional effects on exercise capacity. Methods: 24 CHF patients, NYHA class II/III and accepted for CRT underwent an echocardiogram, QoL questionnaire and CPET with cardiac output (CO) measurements before implantation, at 3 and 6 months. After 3 months, patients were randomized to usual care (UC) or HIT, consisting of 36 sessions at 85–95% of peak V̇O 2. Results: Peak V̇O 2 increased after CRT (17±5.3 to 18.7±6.2 ml/kg/min, p < 0.05); after HIT there was a non-significant increase of 1.4 ml/kg/min (p = 0.12). Peak workload increased after CRT (109±45 to 118±44 W, p = 0.001). An additional significant within- and between group increase after HIT was found in the intervention group (128±42 to 148±48 W, versus 110±50 to 110±50, respectively, p = 0.03). Peak CO did not change significantly after CRT or HIT. V̇O 2 recovery kinetics speeded by 27% after CRT (p = 0.04), no further improvement after HIT was observed. LVEF increased 25% after CRT (p = 0.0001), no additional increase was seen after HIT. Conclusion: This study demonstrates that HIT provides additional improvement of exercise capacity without a concomitant change in peak V̇O 2 or CO suggesting that the additional effect of HIT is mainly mediated by an improvement of anaerobic performance