Influence of O2 pulse on the β-Ga2O3 films deposited by pulsed MOCVD

Introduction: The Anti-Arrhythmic Effects of Exercise Trial reported that aerobic exercise training for 8 weeks after an implantable cardioverter defibrillator (ICD) significantly improved the primary outcome of cardiopulmonary function without ICD shocks or adverse events. This is a report on the longer term outcomes at 24 weeks of exercise maintenance that was continued after aerobic training. Hypothesis: When 8 weeks of aerobic exercise training is followed by aerobic exercise maintenance (50% reduction in the amount of walking), cardiopulmonary function [peak VO2, EX time, VO2 at AT, O2 pulse, METS, Maximum HR] will be maintained without an increase in ICD shocks or hospitalizations. Methods: 160 subjects (80/group) with a prior ICD implant (40% primary and 60% secondary prevention), mean age 55 +12 years, 78% male, 84% Caucasian, 100% beta-blocked, and mean EF%=40%, entered a RCT comparing aerobic exercise to usual care (UC). At baseline, 8 and 24 weeks, participants completed cardiopulmonary exercise testing using a modified Balke treadmill protocol. Aerobic training= 8 weeks of home walking 1 hour/day on 5 days/week at 60-80% of maximum HR using the Karvonen formula, was followed by aerobic maintenance (EX)= 16 weeks of home walking for 150 min/week. ICD shocks and hospitalizations were verified with medical records. Analysis of variance was used to determine group x time effects on study outcomes. Results: Aerobic maintenance significantly increased peak VO2 ml/kg/min, p<0.000 (EX 26.9+7.7, UC 23.4+6.0), EX minutes, p<0.000 (EX 16:27+ 6:36; UC 13:24+4:33), VO2 at AT ml/kg/min, p=0.001 (EX 23.0+6.8; UC 19.8+5.8), O2 pulse p=0.01 (EX 18.7+5.5; UC 16.8+4.9), and METS, p<0.001 (EX 7.6+2.2; UC 6.7+1.8). Maximum HR was unchanged. The number of ICD shocks related to exercise was =1: 3 in UC and 1 in exercise received an ICD shock or ATP during follow-up. There were 11 hospitalizations in each group, none were related to exercise. Conclusions: Aerobic exercise maintenance for 16 weeks that followed aerobic exercise training for 8 weeks, maintained gains in cardiopulmonary function despite reducing the amount of walking by half (300 min vs. 150 min). Aerobic exercise in patients with an ICD is safe without increasing the number of ICD shocks or hospitalizations.

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Cardiorespiratory responses of sedentary college women as a function of training intensity

Journal of Applied Physiology ◽

10.1152/jappl.1976.41.6.822 ◽

1976 ◽

Vol 41 (6) ◽

pp. 822-825 ◽

Cited By ~ 16

Author(s):

J. T. Kearney ◽

G. A. Stull ◽

J. L. Ewing ◽

J. W. Strein

Keyword(s):

Heart Rate ◽

College Women ◽

Experimental Period ◽

Exercise Heart Rate ◽

Training Intensity ◽

Treadmill Speed ◽

Training Response ◽

O2 Pulse ◽

The Difference ◽

Time Required

Twenty-seven sedentary college women trained on a treadmill 3 times weekly over a 9-wk experimental period. Subjects exercised at a heart rate (HR)of either 50 or 65% of the HR reserve added to the resting HR with the duration of each session limited to the time required to elicit 1,000 beats above the resting value. Treadmill speed was adjusted automatically to maintain the prescribed exercise heart rate (EHR) within +/- 5 beats-min(-1). A comparison of the pretraining and posttraining results revealed that both training intensities caused significant increases in VO2max (1-min(-1) and ml-kg(-1)-min(-1)), V at VO2max, and O2 pulse at VO2max, and a significant decrease in VEO2 at VO2max. There was no alteration in EHR at VO2max for either intensity. For every dependent variable in which training effects were noted, the absolute gain made by the subjects training at the 65% intensity was greater than for those exercising at 50%. In no instance, however, was the difference between groups statistically significant. It was concluded that training at an EHR of either 50 or 65% of the HR reserve plus resting HR is sufficient to elicit a training response.

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Maximal exercise responses of tetraplegics and paraplegics

Journal of Applied Physiology ◽

10.1152/jappl.1983.55.2.479 ◽

1983 ◽

Vol 55 (2) ◽

pp. 479-482 ◽

Cited By ~ 82

Author(s):

K. D. Coutts ◽

E. C. Rhodes ◽

D. C. McKenzie

Keyword(s):

Maximal Exercise ◽

International System ◽

Maximal Heart Rate ◽

O2 Uptake ◽

Maximal Power Output ◽

Wheelchair Athletes ◽

Ventilatory Equivalent ◽

Lower Maximum ◽

O2 Pulse ◽

O2 Delivery

Eight tetraplegic and 13 paraplegic subjects performed a continuous progressive loading exercise test to exhaustion on a wheelchair ergometer. Their cardiorespiratory responses at maximal O2 uptake were analyzed after initially grouping subjects according to the international system for classification of wheelchair athletes. Analysis of variance provided a basis for regrouping the subjects into tetraplegic (T), high-lesion paraplegic (HLP), and low-lesion paraplegic (LLP) groups and indicated significant differences (P less than 0.05) in maximal power output (24, 47, and 80 W) and O2 uptake (0.97, 1.62, and 2.42 l/min) for T, HLP, and LLP, respectively. T had a significantly lower maximal heart rate (110) compared with the paraplegic values (175 and 190), whereas the HLP, in contrast to the LLP, had a lower maximum ventilation (66 vs. 101 l/min) and a lower O2 pulse (9.3 vs. 12.7 ml/beat). The ventilatory equivalent for O2 was similar in all groups to values for able-bodied subjects in maximal arm crank ergometry, however, suggesting a lack of any respiratory limit to maximal O2 delivery. No differences were noted in respiratory exchange ratio or net efficiency between the groups. In addition to limitations of functional muscle mass, the data suggested that the reduced cardiac capacity of T and HLP may also be linked to their lower maximal exercise capacity and O2 uptake.

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Decline in VO2max with aging in master athletes and sedentary men

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.5.2195 ◽

1990 ◽

Vol 68 (5) ◽

pp. 2195-2199 ◽

Cited By ~ 196

Author(s):

M. A. Rogers ◽

J. M. Hagberg ◽

W. H. Martin ◽

A. A. Ehsani ◽

J. O. Holloszy

Keyword(s):

Heart Rate ◽

Exercise Training ◽

Maximal Heart Rate ◽

Master Athletes ◽

Endurance Exercise Training ◽

Age Related ◽

O2 Pulse ◽

Rate Of Decline ◽

Sedentary Subjects

Fifteen well-trained master endurance athletes [62.0 +/- 2.3 (SE) yr] and 14 sedentary control subjects (61.4 +/- 1.4 yr) were reevaluated after an average follow-up period of approximately 8 yr to obtain information regarding the effects of physical activity on the age-related decline in maximal O2 uptake capacity (VO2max). The master athletes had been training for 10.2 +/- 2.9 yr before initial testing and continued to train during the follow-up period. The sedentary subjects' VO2max declined by an average of 3.3 ml.kg-1.min-1 (33.9 +/- 1.7 vs. 30.6 +/- 1.6, P less than 0.001) over the course of the study, a decline of 12% per decade. In these subjects maximal heart rate declined 8 beats/min (171 vs. 163) and maximal O2 pulse decreased from 0.20 to 0.18 ml.kg-1.beat (P less than 0.05). The master athletes' VO2 max decreased by an average of 2.2 ml.kg-1.min-1 (54.0 +/- 1.7 vs. 51.8 +/- 1.8, P less than 0.05), a 5.5% decline per decade. The master athletes' maximal heart rate was unchanged (171 +/- 3 beats/min) and their maximal O2 pulse decreased from 0.32 to 0.30 ml.kg-1.beat (P less than 0.05). These findings provide evidence that the age-related decrease in VO2max of master athletes who continue to engage in regular vigorous endurance exercise training is approximately one-half the rate of decline seen in age-matched sedentary subjects. Furthermore our results suggest that endurance exercise training may reduce the rate of decline in maximal heart rate that typically occurs as an individual ages.

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Developmental patterns of O2 consumption, heart rate and O2 pulse in unturned eggs

Respiration Physiology ◽

10.1016/0034-5687(95)00061-5 ◽

1996 ◽

Vol 103 (1) ◽

pp. 83-87 ◽

Cited By ~ 16

Author(s):

J.T. Pearson ◽

M.A. Haque ◽

P-C.L. Hou ◽

H. Tazawa

Keyword(s):

Heart Rate ◽

O2 Consumption ◽

Developmental Patterns ◽

O2 Pulse

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53 Exercise oxygen kinetic in hypertrophic cardiomyopathy: results from a multicentre cardiopulmonary exercise testing study

European Heart Journal Supplements ◽

10.1093/eurheartj/suab133.012 ◽

2021 ◽

Vol 23 (Supplement_G) ◽

Author(s):

Massimo Mapelli ◽

Simona Romani ◽

Damiano Magrì ◽

Marco Merlo ◽

Marco Cittar ◽

...

Keyword(s):

Cardiac Output ◽

Hypertrophic Cardiomyopathy ◽

Exercise Testing ◽

Cardiopulmonary Exercise Testing ◽

Systolic Pressure ◽

Carbon Dioxide Production ◽

Temporal Behaviour ◽

Cardiopulmonary Exercise ◽

O2 Pulse ◽

Dynamic Relationships

Abstract Aims Reduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). We evaluated the cardiopulmonary exercise testing (CPET) response in HCM focusing on parameters strongly associated with stroke volume (SV) and cardiac output (CO), such as oxygen uptake (VO2) and O2-pulse, considering both their absolute values and temporal behaviour during physical exercise. Methods and results We enrolled 312 non-end stage HCM patients, divided according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva manoeuver (72% with LVOTO < 30; 10% between 30 and 49; and 18% ≥50 mmHg). Peak VO2 (percent of predicted), O2-pulse, and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety-six (31%) HCM patients presented an abnormal O2-pulse temporal behaviour, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106 ± 45 vs. 130 ± 49 W), VO2 (74 ± 17% vs. 80 ± 20%) and O2-pulse (12 [9–14] vs. 14 [11–17]ml/beat), with higher VE/VCO2 slope (28 [25–31] vs. 27 [24–31]) (P < 0.005 for all). Only two patients had an abnormal VO2/work slope. Conclusions None of CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal O2-pulse exercise behaviour, which is strongly related to inadequate SV during exercise, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, helping identifying more advanced disease irrespectively of LVOTO. Adding O2-pulse kinetics evaluation to standard CPET could lead to a potential incremental benefit in terms of HCM prognostic stratification and, then, therapeutic management.

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Functional capacity and gender-related differences in Fabry disease

European Heart Journal ◽

10.1093/eurheartj/ehab724.1818 ◽

2021 ◽

Vol 42 (Supplement_1) ◽

Author(s):

G Guglielmi ◽

A Mollo ◽

F Bandera ◽

A Camporeale ◽

M Frigelli ◽

...

Keyword(s):

Heart Rate ◽

Fabry Disease ◽

Functional Capacity ◽

Cardiac Involvement ◽

Beta Blockers ◽

Left Ventricular ◽

Lower Percentage ◽

Chronotropic Incompetence ◽

Chronotropic Response ◽

O2 Pulse

Abstract Background Fabry disease (FD) is a rare x-linked lysosomal storage disease characterized by accumulation of glicosphingolipids in several organs, including the heart. Cardiac involvement manifests as left ventricular (LV) hypertrophy, often complicated by myocardial fibrosis. The impact of disease on functional capacity is not well defined, as well as the potential gender-related differences. Aim To evaluate the functional capacity in a cohort of FD patients with different degree of cardiac involvement. Methods Seventy-two patients were prospectively enrolled from March 2015 to December 2019. Patients underwent cardiac magnetic resonance (CMR) and cardiopulmonary exercise test (CPET) with cycle ergometer. In addition to standard CPET parameters, Chronotropic Index (CI) was calculated as (HR max − HR rest) / (HR max predicted − HR rest), adjusting with HR max predicted calculated as 119 + (HR rest/2) − (age/2) in case of beta-blockers treatment. Results CMR showed left ventricle (LV) hypertrophy (LV mass greater than normal reference value) in 36.1% of patients, LGE and reduced T1 values were detected in 30.6% and 59.7% of subjects respectively. Twenty-eight patients were males (39%), the median age was 40 (28–54) [median (25th–75th)] years and only 11 (15%) subjects were on beta-blockers. All subjects performed a maximal test [RQ max = 1.21 (1.14–1.26)] using a ramp protocol of 15 (15–20) Watt. The absolute peakVO2 was 18.2 (15.75–24.08) mL/min/kg, whilst the percentage of predicted peakVO2 was 67.7 (57.3–76.6)%. The chronotropic response of the overall population was characterized by reduced peak heart rate (HRmax) [80.3 (73.8–87.6)% of predicted], and diminished chronotropic index (CI) [0.67 (0.55–0.77) normal value: 0.80], but preserved heart rate reserve (HRR) [21 (12–28) bpm]. Ventilatory efficiency was preserved [VE/VCO2 = 25.70 (23.18–28.00)]. At gender analysis, men showed higher absolute peakVO2 [men vs females: 19.95 (17.20–28.28) vs 17.80 (15.50–21.28) mL/min/kg, p=0.02] but lower percentage of predicted [64.24 (52.58–70.61) vs 70.75 (59.05–78.02)%, p<0.001] than females. No differences between genders were observed in chronotropic response [HRmax = 138 (108–154) vs 142 (135–153) bpm, p=0.38; HRR = 22 (13–36) vs 20 (11–26), p=0.097; CI: 0.67 (0.51–0.76) vs 0.67 (0.58–0.79), p=0.33], whilst females showed a lower peak O2 pulse (VO2/HR) than males [men vs females: 12.08 (10.04–13.64) vs 7.76 (6.88–9.22), p<0.001], possibly related to gender differences in LV dimensions and stroke volume. Conclusions This large cohort of FD patients with different degree of cardiac involvement showed a significantly impaired functional capacity, mainly characterized by relevant chronotropic incompetence (independent from the use of beta-blockers), consistent with systemic autonomic dysfunction. The degree of chronotropic incompetence was similar between the genders, but females showed higher predicted peakVO2 despite a lower peak O2 pulse. FUNDunding Acknowledgement Type of funding sources: None.

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SO066IS OXYGEN-PULSE A GOOD SURROGATE MARKER OF STROKE VOLUME DURING PEAK EXERCISE IN CHRONIC KIDNEY DISEASE?

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gfaa139.so066 ◽

2020 ◽

Vol 35 (Supplement_3) ◽

Author(s):

Shanmugakumar Chinnappa ◽

Andrew Mooney

Keyword(s):

Chronic Kidney Disease ◽

Kidney Disease ◽

Stroke Volume ◽

Healthy Volunteers ◽

Surrogate Marker ◽

Cross Sectional Study ◽

Peak Exercise ◽

Cross Sectional ◽

Cardiopulmonary Fitness ◽

O2 Pulse

Abstract Background and Aims As there is growing interest in the benefits of exercise training in chronic kidney disease (CKD), it is important to understand the utility of conventional exercise test parameters in quantifying the cardiopulmonary fitness of patients with CKD. Merely extrapolating information from studies of healthy volunteers and heart failure (HF) patients would not suffice. In the present study we evaluated one such parameter, the peak O2-pulse [the rate of peak O2 consumption (VO2max) to peak heart rate (HR)] which is widely used as a surrogate for peak stroke volume (SV) in HF. We tested the hypothesis that peak O2-pulse is a good surrogate marker for peak stroke volume in CKD. Method A cross sectional study of 70 asymptomatic male non-diabetic CKD patients [CKD stages 2-5 (pre dialysis)] without primary cardiac disease. Data from 35 healthy volunteers & 25 HF patients was used for comparison. Specialised cardiopulmonary exercise (CPX) test with CO2 rebreathing technique was utilised to measure peak cardiac output (Qt) and peak SV non-invasively. VO2max was simultaneously measured. Peak O2-pulse was calculated as VO2max/Peak HR. Peripheral O2 extraction [C(a-v)O2] was derived using Fick’s equation, VO2 = Qt x C(a-v)O2. Pearson’s correlation, univariate and multivariate analyses were applied. Results are presented as mean±SD. P<0.05 is considered as significant. Results CKD patients had a mean age of 48.4±12.6 years and a mean eGFR of 33.8±25.5 ml/min. Whereas there was a very strong correlation between peak O2-pulse and peak SV in HF (R2= 0.81), the correlation was less robust in CKD (R2 = 0.49) (Fig 1). On multivariate analysis, in HF, peak SV was the major determinant of O2 pulse (β=1.03). The β for peak C(a-v)O2 was 0.44, both P < 10-3. However, in CKD both peak SV (β =0.76, P<10-3) and peak C(a-v)O2 (β=0.70, P<10-3) were significant determinants of O2-pulse rendering O2-pulse a poor surrogate of SV in CKD. Conclusion Based on the above results we reject the hypothesis that peak O2-pulse is a good surrogate marker of peak SV in CKD. The results highlight the pitfalls in the application of conventional CPX parameters in evaluating cardiopulmonary fitness in CKD. In view of the unique pathophysiology of the uraemic state further CKD-specific studies evaluating the central and peripheral determinants of aerobic exercise capacity are required.

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Abstract 17002: Assessment of Exercise Function in Children With Hypertrophic Cardiomyopathy

Circulation ◽

10.1161/circ.142.suppl_3.17002 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Robert Przybylski ◽

Mark E Alexander ◽

Steven D Colan ◽

Christa Miliaresis ◽

Jonathan Rhodes

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Exercise Performance ◽

Normal Values ◽

Ventricular Outflow Tract ◽

Cardiopulmonary Exercise Test ◽

Left Ventricular ◽

Peak Exercise ◽

Peak Vo2 ◽

O2 Pulse ◽

Established Population

Introduction: Hypertrophic cardiomyopathy (HCM) accounts for nearly half of pediatric cardiomyopathies. While impaired exercise function has been described in adults with HCM, little is known about exercise function in children with HCM. Hypothesis: Children with HCM have impaired exercise function. Methods: A retrospective cohort study was performed. Pts <21 years with a diagnosis of HCM with a cardiopulmonary exercise test (CPET) between November 1, 2002 and May 31, 2019 were included. Pts with syndromic HCM were excluded. CPETs with respiratory exchange ratio <1.09 were excluded. We compared indices of exercise performance to established population normal values using one-sample T-tests. In pts with multiple CPETs, we compared indices of exercise performance from the first to last CPET using paired T-tests. Results: We identified 124 pts with 240 CPETs. The average age at time of CPET was 14.8 ± 3.0 years. Average %predicted peak VO2 (78 ± 20%) was significantly less than the population average (p <0.01), though there was wide variability (range 35-152% predicted). Peak VO2 was <85% predicted in 67%, <50% predicted in 7%, and absolute peak VO2 was <25 cc/kg/min in 30% of tests. However, %predicted peak VO2 was >100% in 13% of tests. The %predicted peak O2 pulse (88 ± 21%; p <0.01; a surrogate for the forward stroke volume at peak exercise) and the %predicted peak heart rate (88.0 ± 12%; p <0.01) were significantly lower than established population normal values. In 63 pts with multiple CPETs, significant declines in %predicted peak VO2 (83 ± 20% v. 75 ± 19%; p <0.01) and O2 pulse (92 ± 22% v. 86 ± 21%; p <0.01) were observed at an average interval of 4.5 years. We found no statistically significant association between %predicted peak VO2 and interventricular septal thickness, resting left ventricular outflow tract gradient or echocardiographic indices of diastolic left ventricular function. Conclusions: Exercise function is at least moderately impaired in a substantial portion of children with HCM and this impairment tends to worsen over time. However, there is a significant subset of patient with remarkably well-preserved exercise function. Echocardiographic measurements did not correlate with exercise function in our cohort.

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Developmental patterns of heart rate in altricial avian embryos and hatchlings

Journal of Experimental Biology ◽

10.1242/jeb.202.11.1545 ◽

1999 ◽

Vol 202 (11) ◽

pp. 1545-1550

Author(s):

J.T. Pearson ◽

Y. Noma ◽

H. Tazawa

Keyword(s):

Heart Rate ◽

Stroke Volume ◽

Direct Proportion ◽

Developmental Patterns ◽

Avian Embryos ◽

Rate Of Increase ◽

Nymphicus Hollandicus ◽

O2 Pulse ◽

Mean Heart Rate

The aims of this study were to determine the patterns of development of heart rate (fH) in altricial avian embryos and hatchlings, and then to examine how fH is regulated to meet metabolic requirements in altricial embryos. Embryonic mean heart rate (fH-) in 12 altricial species (Passeriformes and Psittaciformes) increased during pre-pipping incubation in all species except the cockatiel (Nymphicus hollandicus), in which fH- tended to decrease prior to pipping. The rate of increase in fH- tripled during the pipping phase in all species, and fH- was significantly higher during the pipping period and in hatchlings than during pre-pipping development. The O2 pulse (O2 consumed per cardiac beat) of altricial embryos increased in direct proportion to embryo mass (loge/loge base), although fH- was often low prior to pipping, implying that stroke volume increases in the second half of incubation. We conclude that fH contributes more than other factors towards supplying the metabolic demands of the embryo during the middle of incubation and the final pipping phase, but less during the intervening period of late incubation.

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