Peak Cardiac Output Research Articles

Exercise training affects hemodynamics and exercise capacity in cases of heart failure with preserved ejection fraction: a non-randomized controlled trial in individuals aged 65-80 years.

Exercise training is an established intervention method for improving exercise capacity and survival rates in patients with heart failure with preserved ejection fraction (HFpEF). However, most reports have focused on European and American patients, with limited data regarding the effects of exercise training on cardiac function, hemodynamics, and exercise capacity in East Asian patients. This study investigated the effects of exercise training on cardiac function, hemodynamics, and exercise capacity in Japanese patients aged 65-80 years with HFpEF. This single-center, open-label, non-randomized, controlled trial prospectively enrolled 99 outpatients. Eligibility criteria for HFpEF patients were an HFA score ≥5 in addition to clinical symptoms of heart failure and left ventricular diastolic dysfunction. Exercise training in the intervention group consisted of aerobic exercise and strength training thrice weekly for 5 months. Patients in the control group continued the usual treatment for 5 months. Resting cardiac function was evaluated using echocardiography. Peak oxygen uptake (peakVO2), ventilatory equivalent (VE) vs. carbon dioxide output (VCO2) slope, peak cardiac output index, and arteriovenous oxygen difference were calculated using cardiopulmonary exercise testing combined with impedance cardiography. After 5 months of exercise training, remarkable interactions were observed, with peakVO2 as the primary outcome. Additionally, significant interactions were observed between hemodynamic indices and some echocardiographic parameters. The mean percentage change in peakVO2 from baseline was 8.3% in the intervention group. Fifteen study participants (30.1%) in the intervention group achieved a clinically meaningful change of 3.0 ml/min/kg (10% improvement) in peakVO2 from baseline. The group with 3.0 ml/min/kg or 10% improvement in peakVO2 from baseline had a considerably lower prevalence of diabetes mellitus and VE vs. VCO2 slope and considerably higher left atrial-global longitudinal strain values than the group without any notable improvements. Although exercise training can help improve exercise intolerance in Japanese patients aged 65-80 years with HFpEF, its benefits are limited. Our results suggest that HFpEF, complicated by diabetes mellitus and decreased ventilatory efficiency during exercise, may require reconsideration of intervention strategies. This trial was registered with the University Hospital Medical Information Network, a trial registry in Japan (registration number: UMIN000045474).

Proteomics and Precise Exercise Phenotypes in Heart Failure With Preserved Ejection Fraction: A Pilot Study.

While exercise impairments are central to symptoms and diagnosis of heart failure with preserved ejection fraction (HFpEF), prior studies of HFpEF biomarkers have mostly focused on resting phenotypes. We combined precise exercise phenotypes with cardiovascular proteomics to identify protein signatures of HFpEF exercise responses and new potential therapeutic targets. We analyzed 277 proteins (Olink) in 151 individuals (N=103 HFpEF, 48 controls; 62±11 years; 56% women) with cardiopulmonary exercise testing with invasive monitoring. Using ridge regression adjusted for age/sex, we defined proteomic signatures of 5 physiological variables involved in HFpEF: peak oxygen uptake, peak cardiac output, pulmonary capillary wedge pressure/cardiac output slope, peak pulmonary vascular resistance, and peak peripheral O2 extraction. Multiprotein signatures of each of the exercise phenotypes captured a significant proportion of variance in respective exercise phenotypes. Interrogating the importance (ridge coefficient magnitude) of specific proteins in each signature highlighted proteins with putative links to HFpEF pathophysiology (eg, inflammatory, profibrotic proteins),and novel proteins linked to distinct physiologies (eg, proteins involved in multiorgan [kidney, liver, muscle, adipose] health) were implicated in impaired O2 extraction. In a separate sample (N=522, 261 HF events), proteomic signatures of peak oxygen uptake and pulmonary capillary wedge pressure/cardiac output slope were associated with incident HFpEF (odds ratios, 0.67 [95% CI, 0.50-0.90] and 1.43 [95% CI, 1.11-1.85], respectively) with adjustment for clinical factors and B-type natriuretic peptides. The cardiovascular proteome is associated with precision exercise phenotypes in HFpEF, suggesting novel mechanistic targets and potential methods for risk stratification to prevent HFpEF early in its pathogenesis.

Cardiopulmonary response to exercise in adults born very preterm.

This study aims to compare cardiopulmonary response to aerobic exercise between young adults born very preterm, including a subgroup with bronchopulmonary dysplasia (BPD), and term controls.Seventy-one adults (18-29 years) born <30 weeks' gestational age (24 with BPD) and 73 term controls were recruited. Assessment included cardiopulmonary exercise testing with impedance cardiography. We compared group differences in peak O2 consumption (peak VO2) and in ventilatory and cardiovascular responses to exercise using linear regression analyses.Preterm participants had reduced peak VO2 (mean difference -2.7; 95% CI -5.3, -0.1 mL·kg-1 lean body mass·min-1) versus controls. Those with BPD achieved lower peak work-rate compared to term controls (-21; 95% CI -38, -5 watts). There was no difference across groups in breathing reserve, ventilatory efficiency, peak heart rate and cardiac output. VO2 to work-rate relationship (ΔVO2/ΔWR) was reduced in preterm versus term. Peak systolic blood pressure and circulatory power (systolic blood pressure*VO2) were also lower in BPD versus term controls. In the preterm group, longer NICU stay and lower peak cardiac output were associated with lower peak VO2Results suggest limitations with peripheral O2 uptake in the muscle with reduced ΔVO2/ΔWR and peak circulatory power, but normal cardiac output. Investigations into skeletal muscle perfusion and O2 use during exercise are warranted to better understand mechanisms of exercise limitation.

Sex differences in hemodynamic response to high-intensity interval exercise.

Sex differences in the cardiorespiratory and hemodynamic response to exercise exist due to differences in heart size, blood volume, and hemoglobin mass, eliciting higher maximal oxygen uptake (VO2max ) in men versus women. Data are equivocal whether sex differences in training responsiveness occur. This study investigated potential sex differences in the hemodynamic response (stroke volume (SV) and cardiac output (CO)) to high-intensity interval exercise (HIIE). Habitually active men (n = 15) and women (n = 13) underwent VO2max testing, followed by three HIIE sessions consisting of the 4 × 4, 10 × 1, and reduced exertion high-intensity training (REHIT), whose order was randomized. During exercise, oxygen uptake (VO2 ) and hemodynamic responses were determined. Results showed no sex difference in peak relative VO2 (p = 0.263), CO (p = 0.277), or SV (p = 0.116), although absolute values were higher in men (p < 0.05). Peak absolute (127.3 ± 20.6 vs. 115.2 ± 16.6 mL/beat, p = 0.004, d = 0.66) and relative SV (111.0 ± 15.5 vs. 100.7 ± 11.1% max, p = 0.005, d = 0.78) were higher with REHIT versus 4 × 4. No sex differences in mean relative VO2 , CO, or SV occurred (p > 0.05). Data showed lower mean VO2 during REHIT versus 4 × 4 (59.3 ± 6.8 vs. 65.8 ± 5.8 %VO2max , p < 0.001, d = 1.05) and 10 × 1 (59.3 ± 6.8 vs. 69.1 ± 7.4 %VO2max , p < 0.001, d = 1.4). Mean CO was lower in REHIT than 10 × 1 (79.8 ± 8.6 vs. 84.0 ± 7.4% max, p = 0.012, d = 0.53). Previously reported differences in VO2max response to HIIE may not be due to unique hemodynamic responses.

Haemodynamic and metabolic phenotyping of patients with aortic stenosis and preserved ejection fraction: A specific phenotype of heart failure with preserved ejection fraction?

Degenerative aortic valve stenosis with preserved ejection fraction (ASpEF) and heart failure with preserved ejection fraction (HFpEF) display intriguing similarities. This study aimed to provide a non-invasive, comparative analysis of ASpEF versus HFpEF at rest and during exercise. We prospectively enrolled 148 patients with HFpEF and 150 patients with degenerative moderate-to-severe ASpEF, together with 66 age- and sex-matched healthy controls. All subjects received a comprehensive evaluation at rest and 351/364 (96%) performed a combined cardiopulmonary exercise stress echocardiography test. Patients with ASpEF eligible for transcatheter aortic valve replacement (n = 125) also performed cardiac computed tomography (CT). HFpEF and ASpEF patients showed similar demographic distribution and biohumoral profiles. Most patients with ASpEF (134/150, 89%) had severe high-gradient aortic stenosis; 6/150 (4%) had normal-flow, low-gradient ASpEF, while 10/150 (7%) had low-flow, low-gradient ASpEF. Both patient groups displayed significantly lower peak oxygen consumption (VO2 ), peak cardiac output, and peak arteriovenous oxygen difference compared to controls (all p < 0.01). ASpEF patients showed several extravalvular abnormalities at rest and during exercise, similar to HFpEF (all p < 0.01 vs. controls). Epicardial adipose tissue (EAT) thickness was significantly greater in ASpEF than HFpEF and was inversely correlated with peak VO2 in all groups. In ASpEF, EAT was directly related to echocardiography-derived disease severity and CT-derived aortic valve calcium burden. Functional capacity is similarly impaired in ASpEF and HFpEF due to both peripheral and central components. Further investigation is warranted to determine whether extravalvular alterations may affect disease progression and prognosis in ASpEF even after valve intervention, which could support the concept of ASpEF as a specific sub-phenotype of HFpEF.

Determining Peak Cardiac Output with Inert Gas Rebreathing: Methodological Considerations and Reporting.

Determining Peak Cardiac Output with Inert Gas Rebreathing: Methodological Considerations and Reporting.

Exercise Capacity and Ventilatory Efficiency in Patients With Pulmonary Arterial Hypertension.

Background The symptom for identification of pulmonary arterial hypertension (PAH) is dyspnea on exertion, with a concomitant decrease in exercise capacity. Even patients with hemodynamically improved PAH may have impaired exercise tolerance; however, the effect of central and peripheral factors on exercise tolerance remains unclear. We explored the factors contributing to exercise capacity and ventilatory efficiency in patients with hemodynamically normalized PAH after medical treatment. Methods and Results In total, 82 patients with PAH (age: median 46 [interquartile range, 39-51] years; male:female, 23:59) and mean pulmonary arterial pressure ≤30 mm Hg at rest were enrolled. The exercise capacity, indicated by the 6-minute walk distance and peak oxygen consumption, and the ventilatory efficiency, indicated by the minute ventilation versus carbon dioxide output slope, were assessed using cardiopulmonary exercise testing with a right heart catheter. The mean pulmonary arterial pressure was 21 (17-25) mm Hg, and the 6-minute walk distance was 530 (458-565) m, whereas the peak oxygen consumption was 18.8 (14.8-21.6) mLꞏmin-1ꞏkg-1. The multivariate model that best predicted 6-minute walk distance included peak arterial mixed venous oxygen content difference (β=0.46, P<0.001), whereas the best peak oxygen consumption predictors included peak cardiac output (β=0.72, P<0.001), peak arterial mixed venous oxygen content difference (β=0.56, P<0.001), and resting mean pulmonary arterial pressure (β=-0.25, P=0.026). The parameter that best predicted minute ventilation versus carbon dioxide output slope was the resting mean pulmonary arterial pressure (β=0.35, P=0.041). Quadriceps muscle strength was moderately correlated with exercise capacity (6-minute walk distance; ρ=0.57, P<0.001; peak oxygen consumption: ρ=0.56, P<0.001) and weakly correlated with ventilatory efficiency (ρ=-0.32, P=0.007). Conclusions Central and peripheral factors are closely related to impaired exercise tolerance in patients with hemodynamically normalized PAH.

Functional and prognostic impact of hypertensive response to exercise across the heart failure spectrum

Abstract Funding Acknowledgements Type of funding sources: None. Background Conflicting data exist regarding the prognostic significance of hypertensive response to exercise (HRE), commonly defined according to absolute peak systolic blood pressure (SBP) values. Limited evidence is available regarding the impact of workload-indexed HRE in patients at different stages of the heart failure (HF) spectrum as defined by the American College of Cardiology/American Heart Association HF staging system. Purpose We evaluated the SBP/Workload slope during exercise across the HF spectrum and investigated the haemodynamic, functional and prognostic correlates of HRE. Methods We prospectively enrolled 58 healthy controls, 201 subjects at risk of developing HF (HF Stages A-B), and 369 patients with a definite diagnosis of HF (Stage C); among the latter, 143 had preserved (HFpEF) and 226 reduced (HFrEF) left ventricular ejection fraction. All patients underwent a combined cardiopulmonary-exercise stress echocardiography test. For each patient, we recorded the first (i.e., within the first minute of exercise) and last (i.e., at peak effort) BP measurement during the ramp protocol. The SBP/Workload slope (Figure 1) was calculated as the ratio of the difference in SBP over the corresponding increment in watts (W): (SBPpeak – SBPfirst)/(Wpeak – Wfirst). In each subgroup, we divided patients according to SBP/Workload slope tertiles; HRE was defined as the highest sex-specific SBP/Workload slope tertile in each HF stage. The primary outcome was a composite of all-cause mortality and hospitalization for cardiovascular reasons. Results Median SBP/Workload slope was 0.53 mmHg/W, interquartile range 0.36-0.72 mmHg/W; the slope was 39% steeper in women than in men (p&amp;lt;0.0001). After adjusting for age and sex, SBP/Workload slope in controls (0.43, 0.35-0.57 mmHg/W) was similar to HFrEF (0.47, 0.30-0.63 mmHg/W) but significantly lower than Stages A-B (0.61, 0.47-0.75 mmHg/W) and HFpEF (0.63, 0.42-0.86 mmHg/W). In all HF stages, patients with HRE showed significantly lower peak oxygen consumption and peripheral oxygen extraction. After a median follow-up of 16 months, HRE was independently associated with adverse outcomes (Hazard Ratio 2.05, 95% confidence interval 1.81-5.18), while rest and peak SBP were not. Kaplan-Meier analysis confirmed a worse survival probability in Stages A-B (p=0.005) and HFpEF (p&amp;lt;0.001), but not HFrEF. After adjusting for age, sex, body mass index, rest and peak SBP, rest and peak cardiac output, and rest and peak left ventricular ejection fraction, patients with the highest SBP/Workload slope had a 47% higher risk of the primary outcome than subjects in the lowest tertile (Figure 2). Conclusion HRE, as evaluated by the SBP/Workload slope, is associated with distinct pathophysiological features and impaired functional capacity across the HF spectrum, especially in Stages A-B and in patients with HFpEF. Patients with HRE in these subgroups may be at increased risk of adverse cardiovascular outcomes.

Exercise hemodynamics and metabolisms in (very) sportive patients after orthotopic heart transplantation

Abstract Funding Acknowledgements Type of funding sources: None. Purpose After orthotopic heart transplantation (HTX), patients benefit with improved survival and quality of life, but exercise physiology becomes complicated and exercise capacity usually remains limited at 60-70% of predicted values. However, there are also patients who return to demanding or competitive sports even after HTX. For these patients, optimal exercise hemodynamics and metabolisms are crucial. It was the aim of this study to investigate this question more closely in (very) sportive patients after HTX. Methods 6 patients after orthotopic HTX (1 female, 54±16 yrs old, BMI 23.6±2.8, 11±7 yrs post-transplant) from different sports disciplines (Cycling [2x], Triathlon, Hockey, Table-Tennis, Scuba Diving) could be included (Table 1). We performed cardiopulmonary exercise test (CPET) on a bicycle ergometer using a ramp protocol (15 watts/minute) and consecutive inertgas rebreathing (IGR) on different exercise steps (rest, light, moderate, heavy) of each 4-5 minutes. The hemodynamic measurements and blood gas analysis were conducted at the last minute of each IGR step. The study was approved by the local ethics committee. Results For CPET: one patient reached extraordinary exercise capacity with a peak load of 345 watts (182% of pred.) and a peak VO2 of 58.9 ml/kg/min (163% of pred.). Corresponding values at first ventilatory threshold (VT1) were 280 watts and 44.1 ml/kg/min. The results of the other patients showed a more homogenic profile: Mean peak load was 172±44 watts (104±14% of pred.) and peak VO2 was mean 25.6±4.5 ml/kg/min (91±14% of pred.). Values at VT1 were 108±27 watts and 18.0±2.5 ml/kg/min. Selected IGR results for all patients are displayed in Table 2. The hemodynamic measurements revealed a steadily increase in cardiac output (CO), cardiac index (CI), arteriovenous oxygen difference (avDO2), heart rate and systolic blood pressure from rest to the different exercise steps. However, an increase in stroke volume (SV) beyond light to moderate exercise often remained limited (peak SV 101±14 ml/beat). Also, peak CO (13.9±1.8 l/min) remained slightly below predicted values (89% of pred.). Conclusion Hemodynamic measurements revealed satisfying exercise adaptions and adequate prerequisites for intensive physical activities in selected patients even after HTX. However, compared to healthy athletes, SV was clearly limited to normal values (&amp;lt;120 ml/beat). The deficit in CO occurs with moderate to heavy exercise levels could be partially compensated by increased avDO2 due to excellent peripheral function. Therefore, regular exercise training is crucial for this target group.

Home-Based Buddhist Walking Meditation Mitigates Cardiotoxicity of Anthracycline Chemotherapy in Breast Cancer Patients: A Randomized Controlled Trial.

Purpose: To investigate the effect of walking meditation on vascular function, aerobic fitness, and quality of life in breast cancer patients receiving anthracycline chemotherapy and compare with the nonexercising control group. Methods: Patients aged 40-60 years with newly diagnosed, histologically confirmed resected stage I-II breast cancer were studied in a parallel randomized controlled trial. The participants were randomly assigned to either the nonexercising control group (n = 15) or the Buddhist walking meditation group (n = 15). All participants received four cycles of anthracycline chemotherapy every 3 weeks starting at 2 weeks before the start of the exercise intervention. The walking meditation group performed home-based mindfulness walking exercises at a moderate exercise intensity for 30 min/session, 3 times/week for 12 weeks. The primary outcome measures were vascular reactivity (flow-mediated dilation [FMD]) and arterial stiffness (brachial-ankle pulse wave velocity [baPWV]). Results: Eleven participants from each group completed the entire study. Analysis of variance with repeated measures indicated that FMD and peak oxygen consumption (VO2peak) decreased in both groups after the initiation of anthracycline chemotherapy (all p < 0.05). After the exercise intervention, FMD, VO2peak, peak stroke volume, and peak cardiac output remained lower in the controls, but improved in the walking meditation group (all p < 0.05). baPWV increased in the control group, while no such change was observed in the walking meditation group. There were no significant changes in blood cortisol, malondialdehyde, and interleukin-6 concentrations in both groups. Overall quality of life decreased after 2 weeks of anthracycline chemotherapy in both groups (all p < 0.05). However, the walking meditation group improved many of these symptoms significantly (all p < 0.05), while no such changes were observed in the control group. Conclusions: Buddhist walking meditation exercise was effective in mitigating cardiotoxicity of anthracycline chemotherapy on vascular function, aerobic fitness, and quality of life in breast cancer patients. Clinical trial registration number: NCT02676531.

Effects of Intravenous Pimobendan on Cardiovascular Parameters in Healthy Sedated Cats

This study aimed to investigate the effects of intravenous pimobendan on cardiovascular function and to determine the appropriate dose for clinical usage in cats. Six purpose-bred cats received one of the following treatments: intravenous pimobendan at a single dose of 0.075 mg/kg (low dose [LD] group), 0.15 mg/kg (middle dose [MD] group), 0.3 mg/kg (high dose [HD] group), or saline at 0.1 mL/kg (placebo group). Echocardiography and blood pressure measurements were performed before and 5, 15, 30, 45, and 60 minute after drug administration for each treatment. In the MD and HD groups, the fractional shortening, peak systolic velocity, cardiac output, and heart rate increased significantly. There were no significant differences in blood pressure among the groups. Intravenous pimobendan at 0.15-0.3 mg/kg increased the fractional shortening, peak systolic velocity, cardiac output in healthy cats.

Sex differences in heart failure patients assessed by combined echocardiographic and cardiopulmonary exercise testing.

We aimed to test the differences in peak VO2 between males and females in patients diagnosed with heart failure (HF), using combined stress echocardiography (SE) and cardiopulmonary exercise testing (CPET). Patients who underwent CPET and SE for evaluation of dyspnea or exertional intolerance at our institution, between January 2013 and December 2017, were included and retrospectively assessed. Patients were divided into three groups: HF with preserved ejection fraction (HFpEF), HF with mildly reduced or reduced ejection fraction (HFmrEF/HFrEF), and patients without HF (control). These groups were further stratified by sex. One hundred seventy-eight patients underwent CPET-SE testing, of which 40% were females. Females diagnosed with HFpEF showed attenuated increases in end diastolic volume index (P = 0.040 for sex × time interaction), significantly elevated E/e' (P < 0.001), significantly decreased left ventricle (LV) end diastolic volume:E/e ratio (P = 0.040 for sex × time interaction), and lesser increases in A-VO2 difference (P = 0.003 for sex × time interaction), comparing to males with HFpEF. Females diagnosed with HFmrEF/HFrEF showed diminished increases in end diastolic volume index (P = 0.050 for sex × time interaction), mostly after anaerobic threshold was met, comparing to males with HFmrEF/HFrEF. This resulted in reduced increases in peak stroke volume index (P = 0.010 for sex × time interaction) and cardiac output (P = 0.050 for sex × time interaction). Combined CPET-SE testing allows for individualized non-invasive evaluation of exercise physiology stratified by sex. Female patients with HF have lower exercise capacity compared to men with HF. For females diagnosed with HFpEF, this was due to poorer LV compliance and attenuated peripheral oxygen extraction, while for females diagnosed with HFmrEF/HFrEF, this was due to attenuated increase in peak stroke volume and cardiac output. As past studies have shown differences in clinical outcomes between females and males, this study provides an essential understanding of the differences in exercise physiology in HF patients, which may improve patient selection for targeted therapeutics.

Postexercise Oxygen Uptake Recovery Delay Among Patients with Heart Failure: A Systematic Review

Background: Peak oxygen uptake (VO2) is often the focal point of cardiopulmonary exercise testing among patients with heart failure (HF). Breath-by-breath VO2 kinetic patterns at exercise onset, during low-level and submaximal exercise, and during recovery may provide incremental insight into HF severity and etiologies of exercise limitation. Objective: The aim of this systematic review was to explore VO2 recovery delay (VO2RD) across the spectrum of left ventricular function. Methods: A systematic review was conducted using several online databases (EMBASE, Cumulative Index to Nursing and Allied Health Literature, PubMed and Web of Science). Steps outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses were followed. Search terms included VO2RD OR VO2 off kinetics AND HF, peak VO2 AND recovery. All articles were uploaded to Covidence. Results: Four studies met the inclusion criteria. The definition of VO2RD varied across studies. Recovery delay was consistently observed in HF patients compared to controls indicating VO2RD discriminates between those with and without HF. Control groups showed VO2 decline almost immediately after exercise. VO2RD had a significant positive linear relationship to N-terminal prohormone of brain natriuretic and Doppler echo E/e' while demonstrating an inverse relationship with peak cardiac output and survival duration. Conclusions: VO2RD, unlike peak VO2, is relatively cardiospecific. Oxygen recovery kinetics offer insight into disease severity and discrimination of healthy participants from those with HF.

The effects of cloth face masks on cardiorespiratory responses and VO2 during maximal incremental running protocol among apparently healthy men

We aimed to determine the effects of wearing a cloth face mask on cardiorespiratory response, peak oxygen uptake (Vo2), respiratory muscle effort, and exercise tolerance during incremental exercise. The study had a randomized crossover design: 11 apparently healthy young men performed the Bruce protocol treadmill test in two conditions, wearing a cloth face mask (CFM) and without CFM (CON), in random order. Minute ventilation and oxygen uptake were measured using a mass spectrometry metabolic analyzer; cardiac output (CO) was measured using an impedance CO monitor; and mouth pressure (Pm) was measured and calculated as an integral Pm to assess respiratory muscle effort. Maximal minute ventilation was 13.4 ± 10.7% lower in the CFM condition than in the CON condition (P < 0.001). The peak Vo2 (52.4 ± 5.6 and 55.0 ± 5.1 mL/kg/min in CFM and CON, respectively) and CO were not significantly different between the two conditions. However, the integral value of Pm was significantly higher (P = 0.02), and the running time to exhaustion was 2.6 ± 3.2% lower (P = 0.02) in the CFM condition than in the CON condition. Our results suggest that wearing a cloth face mask increased respiratory muscle effort and decreased ventilatory volume in healthy young men; however, Vo2 remained unchanged. Exercise tolerance also decreased slightly.

Dynamic Indices for the Prediction of Fluid Responsiveness in Laparoscopic Urologic Surgery under General Anaesthesia: An Interventional Study

Objective: This study aims to evaluate the ability of stroke volume variation (SVV), pulse pressure variation (PPV), and change in PVV and SVV after tidal volume challenge testing (ΔPPV and ΔSVV) aiming to predict fluid responsiveness in patients undergoing laparoscopic urologic surgery. Material and Methods: A prospective interventional study was performed with 23 patients undergoing urologic surgery while they were placed in Trendelenburg positions. A Vigileo/FloTrac system was used for the analysis. Hemodynamic data such as: arterial pressure (MAP), heart rate (HR), peak airway pressure (PIP), stroke volume (SV), cardiac output (CO), SVV, and PPV were recorded at the tidal volume settings of 8 mL/kg and 12 mL/kg before, and after a fluid challenge (FC). Fluid responsiveness was defined as an increase in SV(ΔSV) ≥15.0%. Results: After tidal volume challenge tests, there were significant increases in PIP in both groups. PPV increased only in the responders, as opposed to SVV, which increased significantly only in non-responders after tidal volume challenge test. After fluid challenge, PVV and SVV decreased gradually and significantly in both groups. The area under the ROC curves of patients undergoing laparoscopic urologic surgery was 0.872 (95% CI: 0.57-0.96) for ΔPPV, this change was the highest compared to other parameters. The threshold of the ΔPPV of patients undergoing laparoscopic urologic surgery was 4% with a sensitivity at 0.75 and specificity at 0.93. Conclusion: Change in PPV after the tidal volume challenge test from 8 mL/kg to 12 mL/kg can be used as an effective indicator to monitor fluid responsiveness in regards to patients undergoing urologic surgery.

Exercise-Induced Excessive Blood Pressure Elevation Is Associated with Cardiac Dysfunction in Male Patients with Essential Hypertension.

Cardiopulmonary exercise testing (CPET) has been used to explore the blood pressure response and potential cardiovascular system structure and dysfunction in male patients with essential hypertension during exercise, to provide a scientific basis for safe and effective exercise rehabilitation and improvement of prognosis. A total of 100 male patients with essential hypertension (aged 18-60) who were admitted to the outpatient department of the Center for Diagnosis and Treatment of Cardiovascular Diseases of Jilin University from September 2018 to January 2021 were enrolled in this study. The patients had normal cardiac structure in resting state without clinical manifestations of heart failure or systematic regularization of treatment at the time of admission. Symptom-restricted CPET was performed and blood pressure was measured during and after exercise. According to Framingham criteria, male systolic blood pressure (SBP) ≥210 mmHg during exercise was defined as exercise hypertension (EH), and the subjects were divided into EH group (n = 47) and non-EH group (n = 53). Based on whether the oxygen pulse (VO2/HR) plateau appeared immediately after anaerobic threshold (AT), the EH group was further divided into the VO2/HR plateau immediately after AT (EH-ATP) group (n = 19) and EH-non-ATP group (n = 28). The basic clinical data and related parameters, key CPET indicators, were compared between groups. Body mass index (BMI) visceral fat, resting SBP, and SBP variability in EH group were significantly higher than those in non-EH group. Moreover, VO2/HR at AT and the ratio of VO2/HR plateau appearing immediately after AT in EH group were significantly higher than those in the non-EH group. The resting SBP, 15-minute SBP variability, and the presence of VO2/HR plateau were independent risk factors for EH. In addition, work rate (WR) at AT but also WR, oxygen consumption per minute (VO2), VO2/kg, and VO2/HR at peak were significantly lower in the EH-ATP group compared to the EH-non-ATP group. Peak diastolic blood pressure (DBP) increment and decreased △VO2/△WR for AT to peak were independent risk factors for VO2/HR plateau appearing immediately after AT in EH patients. EH patients have impaired autonomic nervous function and are prone to exercise-induced cardiac dysfunction. EH patients with exercise-induced cardiac dysfunction have reduced peak cardiac output and exercise tolerance and impaired vascular diastolic function. CPET examination should be performed on EH patients and EH patients with exercise-induced cardiac dysfunction to develop precise drug therapy and effective individual exercise prescription, to avoid arteriosclerosis and exercise-induced cardiac damage. The retrospective study protocol was approved by medical ethics committee of the First Hospital of Jilin University (AF-IRB-032-06 No. 2021-015). The study was registered with the Chinese Clinical Trials Register, registration number: ChiCTR2100053140.

Cardiometabolic determinants of cardiorespiratory fitness at rest, during exercise and post-exercise periods

We aimed to assess the relationship between cardiorepiratory fitness (CRF) and cardiometabolic parameters among young Nigerian adults. 100 young adults (50 males, 50 females) aged 20-30 years, selected from College of Health Sciences, Nnamdi Azikiwe University, Nigeria, participated in the study. Subjects’ demographic data and medical information were obtained through the use of structured pre-exercise health and lifestyle screening questionnaire, physical examination and morphometric measurements. Exercise test was carried out using a mechanically braked magnetic ergometer bicycle at an incremental workload of 30 W every 2 min until the subject reached a volitional exhaustion. Blood pressure (BP) and heart rate (HR) were measured at rest, during exercise and at post-exercise periods. Data indicated a significantly (Ρ&lt;0.05) lower resting HR and rate pressure product (RPP), but higher targeted HR reserve, %RPP increase, peak oxygen pulse, cardiac output, exercise duration and work rate compared with the intermediate and unfit groups in both sexes. Age and BMI adjusted correlation test also indicated significant associations between peak oxygen consumption (VO2) and resting HR, resting RPP, targeted HR reserve, oxygen pulse, cardiac output, % RPP increase, actual HR reserve, exercise duration, and work rate. In contrast, resting BP, resting pulse pressure, peak systolic blood pressure (SBP), peak HR, percentage maximum HR, SBP recovery and HR recovery did not correlate with peak VO2. The present findings suggest that a multiple approach involving both metabolic and cardiovascular interventions might be appropriate when implementing strategies to enhance CRF and improve general well-being.

Mitochondrial Sensitivity To Submaximal ADP Concentrations Following Bed Rest: A Double Exponential Model Analysis

We recently demonstrated that a 10-day exposure to inactivity/microgravity (bed rest, BR) determined impairments of peak oxygen uptake (V̇O2), peak cardiac output, peripheral and microvascular function, whereas maximal ADP-stimulated mitochondrial respiration ex vivo in isolated permeabilized fibers and muscle V̇O2 off-kinetics in vivo were unaffected. PURPOSE: To evaluate mitochondrial sensitivity to submaximal [ADP]. METHODS: Isolated permeabilized vastus lateralis fibers were analyzed by high-resolution respirometry, before (PRE) and after (POST) a 10-day BR in 10 young males. 11 submaximal titrations of ADP (from 12.5 to 10,000 μM) were utilized to assess complex I + II-linked ADP sensitivity which was analyzed by both a Michaelis-Menten (MM) kinetics equation, with the calculation of the apparent Km by standard methods, and by applying a double-exponential function, with the calculation of [ADP] corresponding to 50% of the maximal mitochondrial respiration ([ADP] at 50% JO2max). RESULTS: The double-exponential function provided a better fitting of the data according to AIC model selection. The sum of squared residuals was substantially lower with the double-exponential vs. MM fitting (411 ± 419 and 1209 ± 495 [pmol/s/mg]2, respectively). R2 was higher with the double-exponential vs. the MM fitting (0.97 ± 0.04 and 0.90 ± 0.05, respectively). Analysis of residuals showed that the fitting by MM markedly overestimated JO2 from 1000 to 2000 μM, and underestimated JO2 from 6000 to 10,000 μM. The apparent Km for MM was lower than the [ADP] at 50% JO2max, both in PRE (843 ± 706 and 1270 ± 1015 μM, respectively) and in POST (375 ± 173 and 409 ± 398 μM, respectively). Only for the [ADP] at 50% JO2max the difference between POST vs. PRE was statistically significant (P = 0.046). CONCLUSIONS: The double-exponential function provided a better fit of experimental data. It might also give insights into cellular mechanisms regulating mitochondrial respiration, possibly related to the transport of nucleotides and phosphate across external and internal mitochondrial membranes, ATP synthase activity and respiratory chain activity. The enhanced mitochondrial sensitivity to submaximal [ADP] after BR could represent an attempt to maintain metabolic homeostasis in the presence of impairments upstream of mitochondria.

Locomotor Muscle Afferent Inhibition Augments Activation Of Locomotor Muscles In Heart Failure Patients During Exercise

Exercise intolerance is a hallmark feature of heart failure with reduced ejection fraction (HFrEF). Locomotor muscle afferent feedback contributes to exercise intolerance in patients with HFrEF. Locomotor muscle afferent inhibition via intrathecal fentanyl, compared to the sham condition (SHAM), results in increased peak workload, cardiac output, and leg oxygen delivery during maximal exercise. To date, the impact of locomotor muscle afferent feedback inhibition on locomotor muscle activation responses during exercise in patients with HFrEF have not been investigated. PURPOSE: To determine the effect of intrathecal fentanyl on vastus lateralis (VL) muscle activation during incremental exercise in patients with HFrEF. METHODS: Patients with HFrEF (n = 7, EF: 35 ± 13%, age: 60 ± 9 yrs, BMI 28.7 ± 5.5 kg/m2) performed an incremental cycle test to task failure with lumbar intrathecal fentanyl (FENT) or SHAM (in randomized order). Electromyography (EMG) of the VL was measured and the root-mean square (RMS) of 10 contractions were averaged at 30 W, 50 W, 70 W, and peak workload. Changes in RMS were normalized as a percent of the SHAM response (unloaded = 0%; peak workload = 100%). RESULTS: Peak workload was significantly greater with FENT compared to SHAM (129 ± 30 vs. 114 ± 31 W, p = 0.04). VL RMS was not different at 30 W between FENT and SHAM (FENT: 44 ± 22 vs. SHAM: 17 ± 33%, p = 0.06). However, VL RMS was greater with FENT compared to SHAM at 50 W (FENT: 82 ± 61 vs. SHAM: 31 ± 24%), 70 W (FENT: 96 ± 56 vs. SHAM: 45 ± 29%), and peak workload (FENT: 167 ± 55 vs. SHAM: 92 ± 10%) (all, p < 0.04). There was no significant relationship between the change in peak workload and VL RMS with FENT with both normalized as a percent of the SHAM response (p = 0.09). CONCLUSION: These data suggest that locomotor muscle afferent feedback may contribute to exercise intolerance via inhibition of locomotor muscle activation during exercise in patients with HFrEF.

Stroke volume and cardiac output during 6 minute-walk tests are strong predictors of maximal oxygen uptake in people after stroke.

The 6-minute walk test (6MWT) is a field test commonly used to predict peak oxygen consumption (VO2peak) in people after stroke. Inclusion of cardiodynamic variables measured by impedance cardiography (ICG) during a 6MWT has been shown to improve prediction of VO2peak in healthy adults but these data have not been considered in people after stroke. This study investigates whether the prediction of VO2peak can be improved by the inclusion of cardiovascular indices derived by impedance cardiography (ICG) during the 6MWT in people after stroke. This was a cross-sectional study. Patients diagnosed with stroke underwent in random order, a maximal cardiopulmonary exercise test (CPET) and 6MWT in separate dates. Heart rate (HR), stroke volume (SV) and cardiac output (CO) were measured by ICG during all tests. Oxygen consumption was recorded by a metabolic cart during the CPET. Recorded data were subjected to multiple regression analyses to generate VO2peak prediction equations. Fifty-nine patients, mean age 50.0±11.7 years were included in the analysis. The mean distance covered in the 6MWT (6MWD) was 294±13 m, VO2peak was 19.2±3.2 ml/min/kg. Mean peak HR, SV and CO recorded during 6MWT were 109±6 bpm, 86.3±8.8 ml, 9.4±1.2 L/min and during CPET were 135±14 bpm, 86.6±9 ml, 11.7±2 L/min respectively. The prediction equation with inclusion of cardiodynamic variables: 16.855 + (-0.060 x age) + (0.196 x BMI) + (0.01 x 6MWD) + (-0.416 x SV6MWT) + (3.587 x CO 6MWT) has a higher squared multiple correlation (R2) and a lower standard error of estimate (SEE) and SEE% compared to the equation using 6MWD as the only predictor. Inclusion of SV and CO measured during the 6MWT in stroke patients further improved the VO2peak prediction power compared to using 6MWD as a lone predictor.