Exercise cardiac output is maintained with advancing age in healthy human subjects: cardiac dilatation and increased stroke volume compensate for a diminished heart rate

Effects of medical therapy and age on cardiac output changes following balloon pulmonary angioplasty: Implications for combination therapy in chronic thromboembolic pulmonary hypertension

BACKGROUND

Some patients with chronic thromboembolic pulmonary hypertension (CTEPH) exhibit exercise intolerance due to reduced cardiac output (CO) even after successful balloon pulmonary angioplasty (BPA). Medical therapy is a potential option for such cases; however, it is unclear which patients necessitate it even after BPA.

METHODS

This study included 286 patients with CTEPH who underwent BPA and right heart catheterization 1 year after the final BPA and classified them into no-medication and withdrawal groups. The no-medication group comprised patients without pulmonary hypertension (PH) medications before and after BPA, while the withdrawal group included patients who received PH medications before BPA and discontinued them after BPA. We assessed differences in the changes in CO after BPA from baseline (ΔCO) between the 2 groups. Additionally, we evaluated the ΔCO among different age categories within each group: younger (<60 years), middle-aged (60-70 years), and older adults (≥70 years).

RESULTS

After adjusting baseline covariates, overall CO did not differ significantly. However, ΔCO was significantly positive in the no-medication group but negative in the withdrawal group (0.32 and -0.33, difference in ΔCO: -0.65, 95% confidence intervals: -0.90 to -0.40). A significantly positive effect on ΔCO was observed in younger and middle-aged individuals, with a significant interaction between age and ΔCO in no-medication groups.

CONCLUSIONS

Increasing CO with BPA alone may be challenging with age in patients with CTEPH. Given that discontinuation of PH medication after BPA decreased CO more than the effect of BPA, medical therapy might be necessary even after successful BPA.

Impact of 12-Month Late-in-Life Exercise Training on Cardiopulmonary Reserve, Static Cardiac Structure, and Function: A Randomized Clinical Trial

OBJECTIVE

Although the cardiac benefits of maintaining a lifelong exercise routine are undisputed, to what extent late-in-life exercise training can ameliorate cardiac aging remains unclear. We examined the impact of a 12-month exercise training program on cardiac reserve, static cardiac structure, and cardiac function in older adults.

DESIGN

This study was a single-center, randomized trial using Zelen design. Participants in the center-based exercise (CBE) group underwent an individualized multicomponent exercise training program.

SETTING AND PARTICIPANTS

In total, 120 community-dwelling older adults aged 65-85 years were evenly divided into a CBE group and a control group.

METHODS

The primary outcome indicator was absolute change in peak oxygen uptake (peakVO2) per kilogram from baseline to 12 months. The secondary outcome indicators were the absolute changes in other cardiopulmonary exercise test indices and cardiac magnetic resonance parameters. This study has been registered at the Chinese Clinical Trial Registry Network (ChiCTR2400081824).

RESULTS

In total, 47 older adults in the control group and 49 in the CBE group ultimately completed the 12-month follow-up and were analyzed. Of all participants, 52 (46.4%) were men, and the mean age was 71.22 ± 4.55 years. The absolute change in peakVO2/kg was significantly different between the CBE and control groups by +3.32 mL/kg/min (95% CI 2.10-4.53; P < .001), and a sex-related difference was observed. Additionally, the right ventricular peak filling and ejection rate improved to a greater degree in the CBE than control group (+65.57 mL/s, P = .006; +56.39 mL/s, P = .026, respectively).

CONCLUSIONS AND IMPLICATIONS

A 12-month exercise training program started later in life was effective in improving cardiopulmonary reserve, and men showed a better response to training than women. The right ventricular function increased after late-in-life exercise training.

Effects of aging and endurance exercise training on cardiorespiratory fitness and cardiac structure and function in healthy midlife and older women

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in women in developed societies. Unfavorable structural and functional adaptations within the heart and central blood vessels with sedentary aging in women can act as the substrate for the development of debilitating CVD conditions such as heart failure with preserved ejection fraction (HFpEF). The large decline in cardiorespiratory fitness, as indicated by maximal or peak oxygen uptake (V̇o2max and V̇o2peak, respectively), that occurs in women as they age significantly affects their health and chronic disease status, as well as the risk of cardiovascular and all-cause mortality. Midlife and older women who have performed structured endurance exercise training for several years or decades of their adult lives exhibit a V̇o2max and cardiac and vascular structure and function that are on par or even superior to much younger sedentary women. Therefore, regular endurance exercise training appears to be an effective preventative strategy for mitigating the adverse physiological cardiovascular adaptations associated with sedentary aging in women. Herein, we narratively describe the aging and short- and long-term endurance exercise training adaptations in V̇o2max, cardiac structure, and left ventricular systolic and diastolic function at rest and exercise in midlife and older women. The role of circulating estrogens on cardiac structure and function is described for consideration in the timing of exercise interventions to maximize beneficial adaptations. Current research gaps and potential areas for future investigation to advance our understanding in this critical knowledge area are highlighted.

Bio-SHARPE: Bioinspired Soft and High Aspect Ratio Pumping Element for Robotic and Medical Applications

The advent of soft robots has solved many issues posed by their rigid counterparts, including safer interactions with humans and the capability to work in narrow and complex environments. While much work has been devoted to developing soft actuators and bioinspired mechatronic systems, comparatively little has been done to improve the methods of actuation. Hydraulically soft actuators (HSAs) are emerging candidates to control soft robots due to their fast responses, low noise, and low hysteresis compared to compressible pneumatic ones. Despite advances, current hydraulic sources for large HSAs are still bulky and require high power availability to drive the pumping plant. To overcome these challenges, this work presents a new bioinspired soft and high aspect ratio pumping element (Bio-SHARPE) for use in soft robotic and medical applications. This new soft pumping element can amplify its input volume to at least 8.6 times with a peak pressure of at least 40 kPa. The element can be integrated into existing hydraulic pumping systems like a hydraulic gearbox. Naturally, an amplification of fluid volume can only come at the sacrifice of pumping pressure, which was observed as a 19.1:1 reduction from input to output pressure. The new concept enables a large soft robotic body to be actuated by smaller fluid reservoirs and pumping plant, potentially reducing their power and weight, and thus facilitating drive source miniaturization. The high amplification ratio also makes soft robotic systems more applicable for human-centric applications such as rehabilitation aids, bioinspired untethered soft robots, medical devices, and soft artificial organs. Details of the fabrication and experimental characterization of the Bio-SHARPE and its associated components are given. A soft robotic squid and an artificial heart ventricle are introduced and experimentally validated.

Estimated standard values of aerobic capacity according to sex and age in a Japanese population: A scoping review

Aerobic capacity is a fitness measure reflecting the ability to sustain whole-body physical activity as fast and long as possible. Identifying the distribution of aerobic capacity in a population may help estimate their health status. This study aimed to estimate standard values of aerobic capacity (peak oxygen uptake [Formula: see text] and anaerobic threshold [AT]/kg) for the Japanese population stratified by sex and age using a meta-analysis. Moreover, the comparison of the estimated standard values of the Japanese with those of other populations was performed as a supplementary analysis. We systematically searched original articles on aerobic capacity in the Japanese population using PubMed, Ichushi-Web, and Google Scholar. We meta-analysed [Formula: see text] (total: 78,714, men: 54,614, women: 24,100) and AT (total: 4,042, men: 1,961, women: 2,081) data of healthy Japanese from 21 articles by sex and age. We also searched, collected and meta-analysed data from other populations. Means and 95% confidence intervals were calculated. The estimated standard values of [Formula: see text] (mL/kg/min) for Japanese men and women aged 4-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 47.6, 51.2, 43.2, 37.2, 34.5, 31.7, 28.6, and 26.3, and 42.0, 43.2, 33.6, 30.6, 27.4, 25.6, 23.4, and 23.1, respectively. The AT/kg (mL/kg/min) for Japanese men and women aged 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 21.1, 18.3, 16.8, 15.9, 15.8, and 15.2, and 17.4, 17.0, 15.7, 15.0, 14.5, and 14.2, respectively. Herein, we presented the estimated standard values of aerobic capacity according to sex and age in a Japanese population. In conclusion, aerobic capacity declines with ageing after 20-29 years of age. Additionally, aerobic capacity is lower in the Japanese population than in other populations across a wide range of age groups. Standard value estimation by meta-analysis can be conducted in any country or region and for public health purposes.

The aorta in humans and African great apes, and cardiac output and metabolic levels in human evolution

Humans have a larger energy budget than great apes, allowing the combination of the metabolically expensive traits that define our life history. This budget is ultimately related to the cardiac output, the product of the blood pumped from the ventricle and the number of heart beats per minute, a measure of the blood available for the whole organism physiological activity. To show the relationship between cardiac output and energy expenditure in hominid evolution, we study a surrogate measure of cardiac output, the aortic root diameter, in humans and great apes. When compared to gorillas and chimpanzees, humans present an increased body mass adjusted aortic root diameter. We also use data from the literature to show that over the human lifespan, cardiac output and total energy expenditure follow almost identical trajectories, with a marked increase during the period of brain growth, and a plateau during most of the adult life. The limited variation of adjusted cardiac output with sex, age and physical activity supports the compensation model of energy expenditure in humans. Finally, we present a first study of cardiac output in the skeleton through the study of the aortic impression in the vertebral bodies of the spine. It is absent in great apes, and present in humans and Neanderthals, large-brained hominins with an extended life cycle. An increased adjusted cardiac output, underlying higher total energy expenditure, would have been a key process in human evolution.

The Time Course of Cardiorespiratory Adaptations to Rowing Indoor Training in Post-Menopausal Women

BACKGROUND

Post-menopausal women have impaired cardiorespiratory responses to exercise compared to young women. Exercise training may counterbalance impairments, but the time-dependent effects of exercise training remain unclear. The current study aims to investigate the effects of rowing training on maximal aerobic capacity and time-course cardiorespiratory adaptations in older women.

METHODS

Female participants (n = 23) were randomly allocated to the experimental group (EXP; n = 23; 66 ± 5 years old) enrolled in rowing exercise training and control group (CON; n = 10; 64 ± 4 years old). The cardiopulmonary exercise test (CET) was performed in a cycle ergometer pre- and post-interventions. Oxygen uptake (VO2), stroke volume (SV), cardiac output (CO), and HR were recorded during CET and analyzed at the peak of the exercise. HR was monitored during exercise recovery, and the index of HRR was calculated by ΔHRR (HRpeak-HR one-minute recovery). Every two weeks, Rowing Stepwise Exercise (RSE) in a rowing machine was performed to track specific adaptations to the exercise modality. HR was continuously recorded during RSE and corrected for the average power of each step (HR/watts). The rowing training protocol consisted of three weekly sessions of 30 min at an intensity corresponding to 60-80% of peak HR for ten weeks.

RESULTS

Rowing exercise training increased VO2, SV, and CO at the peak of the CET, and ΔHRR. Increased workload (W) and reduced HR response to a greater achieved workload (HR/W) during RSE were observed after six weeks of training.

CONCLUSIONS

Rowing exercise training is a feasible method to improve cardiorespiratory performance, vagal reactivation and heart rate adjustments to exercise in older women.

Naked mole-rats maintain cardiac function and body composition well into their fourth decade of life

The prevalence of cardiovascular disease increases exponentially with age, highlighting the contribution of aging mechanisms to cardiac diseases. Although model organisms which share human disease pathologies can elucidate mechanisms driving disease, they do not provide us with innate examples how cardiac aging might be slowed or attenuated. The identification of animal models that preserve cardiac function throughout most of life offers an alternative approach to study mechanisms which might slow cardiac aging. One such species may be the naked mole-rat (NMR), a mouse-sized (40 g) rodent with extraordinary longevity (> 37 years), and constant mortality hazard over its four decades of life. We used a cross-sectional study design to measure a range of physiological parameters in NMRs between 2 and 34 years of age and compared these findings with those of mice aged between 3 months and 2.5 years. We observed a rapid decline in body fat content and bone mineral density in old mice, but no changes in NMRs. Similarly, rhythm disorders (premature atrial and ventricular complexes) occurred in aged mice but not in NMRs. Magnetic resonance and ultrasound imaging showed age-dependent increases in cardiac hypertrophy and diastolic dysfunction in mice which were absent in NMRs. Finally, cardiac stress tests showed an age-dependent decline in normalized cardiac output in mice, which was absent in NMRs. Unlike mice, that manifest several aspects of human cardiac aging, NMRs maintain cardiac function and reserve capacity throughout their long lives and may offer insights on how to delay or prevent cardiac aging.

Systolic and diastolic function during cycling at the respiratory threshold between elderly and young healthy individuals

The hemodynamic consequences of aging have been extensively investigated during maximal incremental exercise. However, less is known about the effects of aging on hemodynamics during submaximal steady-state exercise. The aim of the present investigation was to compare the hemodynamics of healthy elderly and young subjects during an exercise bout conducted at the gas threshold (GET) intensity. Two groups of healthy, physically active subjects were studied: the elderly group—EG (n = 11; > 60 years old) and the young group—YG (n = 13; < 35 years old). Both groups performed a 5-min rectangular exercise test at the GET intensity. Hemodynamics were measured using echocardiography. The main finding was that stroke volume responses were higher in the YG than the EG (72.5 ± 16.7 vs. 52.4 ± 8.4 ml, respectively). The increased stroke volume capacity in the YG was the consequence of a greater capacity to increase cardiac preload and contractility and, to a lesser extent, to reduce systemic vascular resistance. Importantly, the atrial contribution to ventricular diastolic filling was substantially higher in the YG when compared to the EG.

Regenerative strategies for the consequences of myocardial infarction: Chronological indication and upcoming visions

Heart muscle injury and an elevated troponin level signify myocardial infarction (MI), which may result in defective and uncoordinated segments, reduced cardiac output, and ultimately, death. Physicians apply thrombolytic therapy, coronary artery bypass graft (CABG) surgery, or percutaneous coronary intervention (PCI) to recanalize and restore blood flow to the coronary arteries, albeit they were not convincingly able to solve the heart problems. Thus, researchers aim to introduce novel substitutional therapies for regenerating and functionalizing damaged cardiac tissue based on engineering concepts. Cell-based engineering approaches, utilizing biomaterials, gene, drug, growth factor delivery systems, and tissue engineering are the most leading studies in the field of heart regeneration. Also, understanding the primary cause of MI and thus selecting the most efficient treatment method can be enhanced by preparing microdevices so-called heart-on-a-chip. In this regard, microfluidic approaches can be used as diagnostic platforms or drug screening in cardiac disease treatment. Additionally, bioprinting technique with whole organ 3D printing of human heart with major vessels, cardiomyocytes and endothelial cells can be an ideal goal for cardiac tissue engineering and remarkable achievement in near future. Consequently, this review discusses the different aspects, advancements, and challenges of the mentioned methods with presenting the advantages and disadvantages, chronological indications, and application prospects of various novel therapeutic approaches.

Wave Intensity Analysis Combined With Machine Learning can Detect Impaired Stroke Volume in Simulations of Heart Failure

Heart failure is treatable, but in the United Kingdom, the 1-, 5- and 10-year mortality rates are 24.1, 54.5 and 75.5%, respectively. The poor prognosis reflects, in part, the lack of specific, simple and affordable diagnostic techniques; the disease is often advanced by the time a diagnosis is made. Previous studies have demonstrated that certain metrics derived from pressure-velocity-based wave intensity analysis are significantly altered in the presence of impaired heart performance when averaged over groups, but to date, no study has examined the diagnostic potential of wave intensity on an individual basis, and, additionally, the pressure waveform can only be obtained accurately using invasive methods, which has inhibited clinical adoption. Here, we investigate whether a new form of wave intensity based on noninvasive measurements of arterial diameter and velocity can detect impaired heart performance in an individual. To do so, we have generated a virtual population of two-thousand elderly subjects, modelling half as healthy controls and half with an impaired stroke volume. All metrics derived from the diameter-velocity-based wave intensity waveforms in the carotid, brachial and radial arteries showed significant crossover between groups-no one metric in any artery could reliably indicate whether a subject's stroke volume was normal or impaired. However, after applying machine learning to the metrics, we found that a support vector classifier could simultaneously achieve up to 99% recall and 95% precision. We conclude that noninvasive wave intensity analysis has significant potential to improve heart failure screening and diagnosis.

Hill Runner's Physiology, Performance and Nutrition: A Descriptive Study

Objectives: The aim of this descriptive study was to characterise anthropometric variables, aerobic capacity, running performance and energy intake and expenditure of hill runners in free-living conditions, and to investigate the relationship between age, anthropometric variables, aerobic capacity and running performance.

Methods: Twenty-eight hill runners participated in this study (17 males and 11 females; aged 18–65 years). Body fat percentage estimate, sum of eight skinfolds (triceps, subscapular, biceps, iliac crest, supraspinale, abdominal, front thigh and medial calf) and maximal oxygen capacity (VO₂max) were assessed in a laboratory setting. Participants also completed a timed hill run (Dumyat Hill, Scotland, ascent: 420 m, distance: 8 km) while wearing a portable gas analyzer to assess oxygen consumption (VO₂). Energy intake and energy expenditure were assessed in free-living conditions over three consecutive days different from the testing days through self-reported food diaries and accelerometers.

Results: VO₂max assessed in the lab (51.2 ± 7.6 ml·min⁻¹·kg⁻¹) showed a weak negative relationship with age [rs(23) = −0.38, p = 0.08]. Neither body fat percentage (median 12.4; IQR 10.1–17.1) nor the sum of skinfolds (median 81.8; IQR 62.4–97.8 mm) correlated with age [rs(28) = 0.001, p = 0.10 and 26 rs(28) = −0.02, p = 0.94, respectively]. The observed intensity of the hill run was 89 ± 6% of the age predicted maximum heart rate and 87 ± 9% of the VO₂max observed in the lab. Hill running performance correlated with VO₂max [r(21) = 0.76, p < 0.001], age [rs(26) = −0.44, p = 0.02] and with estimated body fat percentage and sum of skinfolds [rs(26) = −0.66, p < 0.001 and rs(26) = −0.49, p = 0.01, respectively]. Energy intake negatively correlated with age [rs(26) = −0.43, p = 0.03], with the overall energy intake being significantly lower than the total energy expenditure (2273 ± 550 vs. 2879 ± 510 kcal·day⁻¹; p < 0.001; d = 1.05).

Conclusion: This study demonstrated that hill running performance is positively associated with greater aerobic capacity and negatively associated with increases in adiposity and age. Further, the study highlights that hill runners are at risk of negative energy balance.

Effects of Aging on Hemodynamic Kinetics in Different Intensities of Dynamic Exercise

Healthy aging hemodynamics is known to exhibit a time-dependent loss of function. We aimed at verifying whether older men would have a slowed cardiac output and stroke volume dynamics in response to the onset ("on") and on recovery ("off") of exercise in comparison to young men. Twenty healthy active men (10 young and 10 older) were recruited. Participants performed an incremental cardiopulmonary exercise testing on a cycle ergometer, and on another day, 3 constant workload tests in different intensities. Compared to younger, older men exhibited a slower cardiac output and stroke volume dynamics in both on and off transients for all exercise intensities (all P < 0.05). During higher intensities, both younger and older men had slower hemodynamic kinetics compared to lower intensities (all P < 0.05). There was strong negative relationship between the time constant of cardiac output on-kinetics during high-intensity with maximal exercise performance in both groups (r = -0.88, P < 0.01). We interpret these findings to mean that healthy older men have slowed hemodynamic kinetics compared to younger, but this difference becomes less evident in higher intensities of exercise.

Effect of Combined Ventricular-Arterial Stiffening on Exercise Hemodynamics in Adults With Repaired Coarctation of Aorta

Background

Patients with coarctation of aorta (COA) have arterial stiffening, and this is associated with impaired cardiac reserve and hypertensive systolic blood pressure (SBP) response during exercise. However, whether patients with COA have concomitant left ventricular (LV) stiffening and the potential impact of combined ventricular-arterial stiffening on exercise hemodynamics are unknown.

Methods

We studied 174 patients with repaired COA (aged 39 ± 11 years and male 103 [59%]) and 174 matched controls. Our study hypotheses are: (1) patients with COA have higher ventricular-arterial stiffness (end-systolic elastance [Ees] and arterial elastance [Ea]) as compared with controls; (2) ventricular-arterial stiffness was associated with LV stroke volume augmentation (ΔLVSV) and SBP augmentation (ΔSBP) during exercise among patients with COA.

Results

Despite similar systolic SBP, patients with COA had higher Ea (1.8 ± 0.4 vs 1.4 ± 0.4 mm Hg/mL, P < 0.001), higher Ees (2.41 ± 0.65 vs 2.17 ± 0.40 mm Hg/mL, P < 0.001), but similar Ea/Ees (0.87 ± 0.29 vs 0.83 ± 0.33, P = 0.2). ΔLVSV was 6.1 ± 1.4 mL/beat. Combined ventricular-arterial stiffness had a stronger correlation with ΔLVSV as compared with Ea alone (r = −0.53 vs r = −0.41, P = 0.006) and as compared with Ees alone (r = −0.53 vs r = −0.46, P = 0.02). ΔSBP was 48 ± 21 mm Hg. Combined ventricular-arterial stiffness had a stronger correlation with ΔSBP as compared with Ea alone (r = 0.57 vs r = 0.43, P < 0.001) and as compared with Ees alone (r = 0.57 vs r = −0.39, P < 0.001).

Conclusion

Patients with COA had combined ventricular-arterial stiffening, and this was associated with impaired cardiac reserve and hypertensive SBP response during exercise. These findings provide foundation for further studies to determine whether drugs that reduce both ventricular and arterial stiffness will improve exercise capacity and hemodynamics in this unique population.

The effect of age on mechanisms of exercise tolerance: Reduced arteriovenous oxygen difference causes lower oxygen consumption in older people

OBJECTIVE

To assess the effect of age on mechanisms of exercise tolerance.

METHODS

Prospective observational study recruited 71 healthy individuals divided into two groups according to their age i.e. younger (≤40 years of age, N = 43); and older (≥55 years of age, N = 28). All participants underwent maximal graded cardiopulmonary exercise stress testing using cycle ergometer with simultaneous non-invasive gas-exchange and central haemodynamic measurements. Using the Fick equation, arteriovenous O₂ difference was calculated as the ratio between measured O₂ consumption and cardiac output.

RESULTS

The mean age of younger and older participants was 26.0 ± 5.7 years, and 65.1 ± 6.6 years respectively. Peak O₂ consumption was significantly lower in older compared to the younger age group (18.8 ± 5.2 vs 34.4 ± 9.8 mL/kg/min, p < 0.01). Peak exercise cardiac output and cardiac index were not significantly different between the younger and older age groups (22.7 ± 5.0 vs 22.1 ± 3.9 L/min, p = 0.59; and 12.4 ± 2.9 vs 11.8 ± 1.9 L/min/m², p = 0.29). Despite demonstrating significantly lower peak heart rate by 33 beats/min (129 ± 18.3 vs 162 ± 19.9, p < 0.01), older participants demonstrated significantly higher stroke volume and stroke volume index compared to the younger age group (173 ± 41.5 vs 142 ± 34.9 mL/min, p < 0.01; and 92.1 ± 18.1 vs 78.3 ± 19.5 mL/m², p < 0.01). Arteriovenous O₂ difference was significantly lower in older compared to younger age group participants (9.01 ± 3.0 vs 15.8 ± 4.3 mlO₂/100 mL blood, p < 0.01).

CONCLUSION

Ability of skeletal muscles to extract delivered oxygen represented by reduced arteriovenous O₂ difference at peak exercise appears to be the key determinant of exercise tolerance in healthy older individuals.

Reduced cardiac response to the adrenergic system is a key limiting factor for physical capacity in old age

Ageing is associated with a progressive reduction in physical capacity reducing quality of life. One key physiological limitation of physical capacity that deteriorates in a progressive age-dependent manner is cardiac reserve. Peak cardiac output falls progressively with advancing age such that in extreme old age there is limited ability to enhance cardiac output beyond basal function as is required to support the increased metabolic needs of physical activity. This loss of dynamic range in cardiac output associates with a progressive reduction in the heart's response to adrenergic stimulation. A combination of decreases in the expression and functioning of beta1 adrenergic receptors partially underlies this change. Changes in end effector proteins also have a role to play in this decline. Alterations in the efficiency of excitation-contraction coupling contribute to the reduced chronotropic, inotropic and lusitropic responses of the aged heart. Moderate to vigorous endurance exercise training however has some potential to counter elements of these changes. Further studies are required to fully elucidate the key pivotal mechanisms involved in the age-related loss of response to adrenergic signalling to allow targeted therapeutic strategies to be developed with the aim of preserving physical capacity in advanced old age.

Relationship of Age With the Hemodynamic Parameters in Individuals With Elevated Blood Pressure

BACKGROUND

Age is known to be associated with the prevalence and pathophysiology of hypertension. However, there is little information on whether age stands as a good proxy for the specific hemodynamic profile of an individual with elevated blood pressure (BP), which could be important in the selection of therapy.

DESIGN

This is a cross-sectional study.

SETTING

People who underwent a noninvasive, hemodynamic assessment using impedance cardiography at 51 sites of iKang Health Checkup Centers throughout China between January 2012 and October 2018.

PARTICIPANTS

We included 116,851 individuals, aged 20 to 80 years.

MAIN OUTCOMES AND MEASURES

Relationship between age and hemodynamic parameters (cardiac index, systemic vascular resistance index [SVRI]), among individuals with elevated BP (systolic BP ≥130 mm Hg or diastolic BP ≥80 mm Hg).

RESULTS

Final study population included 45,082 individuals with elevated BP: 29,194 men and 15,888 women with a mean (±SD) age of 48 (±13) and 54 (±12) years, respectively. Cardiac index was negatively associated with age with an adjusted, per decade decrease of 0.17 (95% confidence interval [CI] = 0.17-0.18) L/min/m² in men and 0.24 (95% CI = 0.23-0.25) L/min/m² in women. SVRI was positively associated with age with an adjusted, per-decade increase of 174.2 (95% CI = 168.8-179.7) dynes·s·cm^-5 ·m² in men and 214.1 (95% CI = 204.3-223.8) dynes·s·cm^-5 ·m² in women. However, there was substantial overlap in the distribution of these parameters across different age groups in both sexes.

CONCLUSIONS

In this large study, we observed that cardiac index decreased and SVRI increased with age among individuals with elevated BP. Even though there was a general trend with age, we observed heterogeneity within age strata, suggesting that age alone is inadequate to indicate the hemodynamic profile for an individual. J Am Geriatr Soc 68:1520-1528, 2020.

Echocardiographic evaluation of cardiac function in cynomolgus monkeys over a wide age range

Various cardiovascular diseases can be detected and diagnosed using echocardiography. The demand for cardiovascular system research using nonhuman primates is increasing, but echocardiographic references for nonhuman primates are limited. This report describes the first comparison of echocardiographic reference values in 247 normal cynomolgus monkeys (135 females, 112 males) over a wide age range. Echocardiography, electrocardiography, blood pressure and chest X-ray images were acquired under immobilization with intramuscular ketamine hydrochloride, then cardiac structure, function, and flow velocity were assessed. Cardiac hormone levels were also tested. We found that cardiac structures positively correlated with weight, that the size of these structures stabilized after reaching maturity and that cardiac output increased according to heart size. In contrast, fractional shortening of the left ventricle, ejection fraction and flow velocity showed no significant correlations with weight or age, and age and E wave correlated negatively. These findings appear sufficiently similar to those in humans to suggest that cynomolgus monkeys can serve as a suitable model of human cardiac disease. Our data should also prove useful for surveying cardiac dysfunction in monkeys.

Impaired neuronal sodium channels cause intranodal conduction failure and reentrant arrhythmias in human sinoatrial node

Mechanisms for human sinoatrial node (SAN) dysfunction are poorly understood and whether human SAN excitability requires voltage-gated sodium channels (Nav) remains controversial. Here, we report that neuronal (n)Nav blockade and selective nNav1.6 blockade during high-resolution optical mapping in explanted human hearts depress intranodal SAN conduction, which worsens during autonomic stimulation and overdrive suppression to conduction failure. Partial cardiac (c)Nav blockade further impairs automaticity and intranodal conduction, leading to beat-to-beat variability and reentry. Multiple nNav transcripts are higher in SAN vs atria; heterogeneous alterations of several isoforms, specifically nNav1.6, are associated with heart failure and chronic alcohol consumption. In silico simulations of Nav distributions suggest that I_Na is essential for SAN conduction, especially in fibrotic failing hearts. Our results reveal that not only cNav but nNav are also integral for preventing disease-induced failure in human SAN intranodal conduction. Disease-impaired nNav may underlie patient-specific SAN dysfunctions and should be considered to treat arrhythmias.

The role of of voltage-gated sodium channels (Nav) in pacemaking and conduction of the human sinoatrial node is unclear. Here, the authors investigate existence and function of neuronal and cardiac Nav in human sinoatrial nodes, and demonstrate their alterations in explanted human diseased hearts.

Aging and Physiological Lessons from Master Athletes

Sedentary aging is often characterized by physical dysfunction and chronic degenerative diseases. In contrast, masters athletes demonstrate markedly greater physiological function and more favorable levels of risk factors for cardiovascular disease, osteoporosis, frailty, and cognitive dysfunction than their sedentary counterparts. In many cases, age-related deteriorations of physiological functions as well as elevations in risk factors that are typically observed in sedentary adults are substantially attenuated or even absent in masters athletes. Older masters athletes possess greater functional capacity at any given age than their sedentary peers. Impressive profiles of older athletes provide insight into what is possible in human aging and place aging back into the domain of "physiology" rather than under the jurisdiction of "clinical medicine." In addition, these exceptional aging athletes can serve as a role model for the promotion of physical activity at all ages. The study of masters athletes has provided useful insight into the positive example of successful aging. To further establish and propagate masters athletics as a role model for our aging society, future research and action are needed. © 2020 American Physiological Society. Compr Physiol 10:261-296, 2020.

Dyspnea Postpulmonary Embolism From Physiological Dead Space Proportion and Stroke Volume Defects During Exercise

BACKGROUND

Many patients with pulmonary embolism (PE) report dyspnea on exertion following long-term treatment. Increased physiological dead space proportion (V_D/V_T) and decreased cardiac stroke volume reserve may distinguish persistent effects of PE itself from symptoms reflecting comorbid conditions or deconditioning.

METHODS

This retrospective study analyzed a consecutive series of incremental symptom-limited cardiopulmonary exercise tests that had been ordered to evaluate persistent dyspnea on exertion following long-term treatment for acute PE. Physiological V_D/V_T was determined at anaerobic threshold from exhaled CO₂ and transcutaneous Pco₂ (validated against Paco₂ measurements). Cardiac stroke volume reserve was estimated at rest and at anaerobic threshold by using oxygen consumption/pulse and previously validated estimates of the arteriovenous oxygen content difference.

RESULTS

Cardiopulmonary exercise tests were performed on 40 patients with post-PE dyspnea. In 65.0% (95% CI, 50.2-79.8), V_D/V_T at anaerobic threshold was abnormally elevated, stroke volume reserve was decreased, or both defects occurred. V_D/V_T at anaerobic threshold was abnormally elevated (≥ 0.27) in 35.0% (95% CI, 20.2-49.8). V_D/V_T at anaerobic threshold significantly correlated with the extent of unmatched perfusion defects on subsequent ventilation-perfusion scans (P = .0085). In 55.0% (95% CI, 39.6-70.4), stroke volume reserve at anaerobic threshold was abnormally decreased (≤ 128% of the resting value). Both defects were present in 25.0% (95% CI, 11.6-38.4).

CONCLUSIONS

Increased V_D/V_T at anaerobic threshold and decreased stroke volume reserve during exercise are common among patients with dyspnea on exertion after long-term treatment of PE. The defects can be disclosed noninvasively by using cardiopulmonary exercise testing.

Healthy Aging and Cardiovascular Function: Invasive Hemodynamics During Rest and Exercise in 104 Healthy Volunteers

OBJECTIVES

The aim of this study was to evaluate the association between age and invasive cardiovascular hemodynamics during upright exercise among healthy adults.

BACKGROUND

The marked age-related decline in maximal exercise oxygen uptake (peak VO₂) may contribute to the high burden of heart failure among older individuals and their greater severity of exertional symptoms. However, the mechanisms underlying this decline are not well understood.

METHODS

A total of 104 healthy community-dwelling volunteers age 20 to 76 years well screened for cardiovascular disease underwent exhaustive upright exercise with brachial and pulmonary artery catheters; radionuclide ventriculography; and expired gas analysis for the measurement of peak VO₂, cardiac output, left ventricular stroke volume, end-diastolic volume, end-systolic volume, ejection fraction, pulmonary capillary wedge pressure, and arteriovenous oxygen difference.

RESULTS

Over a 5.5-decade age range, there was a 40% decline in peak VO₂ due primarily to reduced peak exercise cardiac output; peak arteriovenous oxygen difference was unaffected by age. The lower age-related exercise cardiac output was related to lower peak exercise heart rate and stroke volume. Aging was also associated with lower peak exercise ejection fraction, indicating reduced inotropic reserve. Peak exercise end-diastolic volume was lower with aging despite similar left ventricular filling pressure, suggesting age-related reduced diastolic compliance limiting the use of the Frank-Starling mechanism to compensate for reduced chronotropic and inotropic reserves. These age relationships were unaffected by sex.

CONCLUSIONS

The age-related decline in exercise capacity among healthy persons is due predominantly to cardiac mechanisms, including reduced chronotropic and inotropic reserve and possibly reduced Frank-Starling reserve. Peak exercise left ventricular filling pressure and arteriovenous oxygen difference are unchanged with healthy aging.

Modeling arterial pulse waves in healthy aging: a database for in silico evaluation of hemodynamics and pulse wave indexes

The arterial pulse wave (PW) is a rich source of information on cardiovascular (CV) health. It is widely measured by both consumer and clinical devices. However, the physical determinants of the PW are not yet fully understood, and the development of PW analysis algorithms is limited by a lack of PW data sets containing reference CV measurements. Our aim was to create a database of PWs simulated by a computer to span a range of CV conditions, representative of a sample of healthy adults. The typical CV properties of 25-75 yr olds were identified through a literature review. These were used as inputs to a computational model to simulate PWs for subjects of each age decade. Pressure, flow velocity, luminal area, and photoplethysmographic PWs were simulated at common measurement sites, and PW indexes were extracted. The database, containing PWs from 4,374 virtual subjects, was verified by comparing the simulated PWs and derived indexes with corresponding in vivo data. Good agreement was observed, with well-reproduced age-related changes in hemodynamic parameters and PW morphology. The utility of the database was demonstrated through case studies providing novel hemodynamic insights, in silico assessment of PW algorithms, and pilot data to inform the design of clinical PW algorithm assessments. In conclusion, the publicly available PW database is a valuable resource for understanding CV determinants of PWs and for the development and preclinical assessment of PW analysis algorithms. It is particularly useful because the exact CV properties that generated each PW are known.NEW & NOTEWORTHY First, a comprehensive literature review of changes in cardiovascular properties with age was performed. Second, an approach for simulating pulse waves (PWs) at different ages was designed and verified against in vivo data. Third, a PW database was created, and its utility was illustrated through three case studies investigating the determinants of PW indexes. Fourth, the database and tools for creating the database, analyzing PWs, and replicating the case studies are freely available.

Can the shock index be a reliable predictor of early mortality after trauma in older patients? A retrospective cohort study

Aim

Older patients have different physiological characteristics; thus, the reliability of the shock index (SI) to predict mortality could depend on age. We investigated whether the SI is a reliable predictor of early mortality in older patients and evaluated the clinical benefit of age in the interpretation of the SI.

Methods

Using data from the Japan Trauma Data Bank, we identified injured patients aged 20–84 years. Area under the receiver operating characteristic curve (AUC) was used to evaluate the discrimination ability of the SI to predict early mortality. A formula to determine the cut‐off for each age was derived using linear regression analysis. Performance of the new method was compared with that of the traditional SI cut‐off of ≥0.9 AUC.

Results

We analyzed data from 146,802 patients. Early mortality was observed in 4% of patients. The AUC showed a significant negative correlation with age (Spearman's ρ = –0.97, P < 0.001), and it decreased from 0.788 (95% confidence interval [CI], 0.761–0.815) in the 20–24 years age group to 0.660 (95% CI, 0.643–0.676) in those aged 80–84 years. By adjusting for age in the SI interpretation, AUC significantly improved from 0.681 (95% CI, 0.675–0.688) to 0.695 (95% CI, 0.688–0.701) (P < 0.001).

Conclusions

The performance of the SI to predict mortality after trauma was significantly worse in older patients. Even if the SI cut‐off value was adjusted based on age, the decrease in performance was not sufficiently prevented. Our results indicated that clinicians should be cautious when using the SI in older patients.

Quantification of porcine myocardial perfusion with modified dual bolus MRI - a prospective study with a PET reference

BACKGROUND

The reliable quantification of myocardial blood flow (MBF) with MRI, necessitates the correction of errors in arterial input function (AIF) caused by the T1 saturation effect. The aim of this study was to compare MBF determined by a traditional dual bolus method against a modified dual bolus approach and to evaluate both methods against PET in a porcine model of myocardial ischemia.

METHODS

Local myocardial ischemia was induced in five pigs, which were subsequently examined with contrast enhanced MRI (gadoteric acid) and PET (O-15 water). In the determination of MBF, the initial high concentration AIF was corrected using the ratio of low and high contrast AIF areas, normalized according to the corresponding heart rates. MBF was determined from the MRI, during stress and at rest, using the dual bolus and the modified dual bolus methods in 24 segments of the myocardium (total of 240 segments, five pigs in stress and rest). Due to image artifacts and technical problems 53% of the segments had to be rejected from further analyses. These two estimates were later compared against respective rest and stress PET-based MBF measurements.

RESULTS

Values of MBF were determined for 112/240 regions. Correlations for MBF between the modified dual bolus method and PET was r_s = 0.84, and between the traditional dual bolus method and PET r_s = 0.79. The intraclass correlation was very good (ICC = 0.85) between the modified dual bolus method and PET, but poor between the traditional dual bolus method and PET (ICC = 0.07).

CONCLUSIONS

The modified dual bolus method showed a better agreement with PET than the traditional dual bolus method. The modified dual bolus method was found to be more reliable than the traditional dual bolus method, especially when there was variation in the heart rate. However, the difference between the MBF values estimated with either of the two MRI-based dual-bolus methods and those estimated with the gold-standard PET method were statistically significant.

Clinical pharmacology of old age

Introduction: With the majority of elderly persons consuming multiple drugs, inappropriate drug use is a major issue in geriatric medicine. Areas covered: We reviewed PubMed, Embase, and Cochrane from inception to 1 May 2019 for potentially inappropriate use of medications, polypharmacy, and age-dependent changes in pharmacokinetics and pharmacodynamics. We selected to highlight new aspects that have emerged in recent years: appropriate monitoring of drug adherence and the introduction of Big Data analysis in advancing geriatric pharmacology. Expert opinion: There are major gaps in the pharmacological treatment of the elderly. Most drugs were designed and tested in adults, with no pharmacokinetic and pharmacodynamic data on changes in old age. This void must be corrected through systematic and well-designed research programs. Potentially inappropriate use of medications (PIM) in the elderly is a serious issue in advanced age. Analysis of PIM shows relatively low predictive value in real life medicine. Most physicians continue to prescribe to the elderly medicines which should not be given at all, or not combined. Polypharmacy is a complex issue in old age, and in many cases treating physicians are not conducting critical assessment of the need for numerous medications.

In vitro assessment of pacing as therapy for aortic regurgitation

Background and objective

Clinical evaluation of pacing therapy in mitigating the aortic insufficiency after transchateter aortic valve implantation often gives contradictory outcomes. This study presents an in vitro investigation aimed at clarifying the effect of pacing on paravalvular leakage.

Methods

A series of in vitro tests reproducing the heart operating changes clinically obtained by pacing was carried out in a 26 mm Edwards Sapien XT prosthesis with mild paravalvular leakage. The effect of pacing on the regurgitant volumes per cycle and per minute was quantified, and the energy and power consumed by the left ventricle were calculated.

Results

Results indicate that though pacing results in some reduction in the total regurgitation per cycle, the volume of fluid regurgitating per minute increases substantially, causing overload of left ventricle.

Conclusions

Our tests indicate no effective haemodynamic benefit from pacing, suggesting a prudential clinical use of this therapy for the treatment of postoperative aortic regurgitation.

Cardiac function is not associated with glucose control in older women

The present study evaluated the effect of age on glucose tolerance and cardiac function and assessed the relationship between metabolic control and cardiac function and performance. Thirty-four healthy women aged 40 to 81 years were divided into two age groups: younger (≤50 years of age, N = 19) and older (≥60 years of age, N = 15). Participants performed an oral glucose tolerance test and a graded cardiopulmonary exercise test with non-invasive haemodynamic measurements. Compared to younger, older women demonstrated significantly higher 2-hour glucose (4.67 ± 1.01 vs 6.08 ± 1.54 mmol/l, P < 0.01), but lower peak exercise O₂ consumption (1.96 ± 0.44 vs 1.38 ± 0.26 l/min, P < 0.01) and cardiac power output (4.06 ± 0.76 vs 3.35 ± 0.73 W, P = 0.01). When data from all study participants were combined, there was a significant negative relationship between 2-hour glucose and peak cardiac power (r = -0.39, P = 0.02), and peak O₂ consumption (r = -0.40, P = 0.02). The strength of these relationships was affected by age, with moderate negative relationship identified between 2-hour glucose and peak cardiac power output in younger compared to older participants (r = -0.38, P = 0.11 vs. r = -0.09, P = 0.75). Metabolic control and cardiac function decline with age. The lack of relationship between glucose control and cardiac power may suggest that metabolic control does not influence cardiac function and performance in older women.

Muscle morphology and performance in master athletes: A systematic review and meta-analyses

INTRODUCTION

The extent to which chronic exercise training preserves age-related decrements in physical function, muscle strength, mass and morphology is unclear. Our aim was to conduct a systematic review of the literature to determine to what extent chronically trained master athletes (strength/power and endurance) preserve levels of physical function, muscle strength, muscle mass and morphology in older age, compared with older and younger controls and young trained individuals.

METHODS

The systematic data search included Medline, EMBASE, SPORTDiscus, CINAHL and Web of Science databases.

INCLUSION CRITERIA

i) master athletes mean exercise training duration ≥20 years ii) master athletes mean age of cohort >59 years) iii) at least one measurement of muscle mass/volume/fibre-type morphology and/or strength/physical function.

RESULTS

Fifty-five eligible studies were identified. Meta-analyses were carried out on maximal aerobic capacity, maximal voluntary contraction and body composition. Master endurance athletes (42.0 ± 6.6 ml kg^-1 min^-1) exhibited VO_2max values comparable with young healthy controls (43.1 ± 6.8 ml kg^-1 min^-1, P = .84), greater than older controls (27.1 ± 4.3 ml kg^-1 min^-1, P < 0.01) and master strength/power athletes (26.5 ± 2.3 mlkg^-1 min^-1, P < 0.01), and lower than young endurance trained individuals (60.0 ± 5.4 ml kg^-1 min^-1, P < 0.01). Master strength/power athletes (0.60 (0.28-0.93) P < 0.01) and young controls (0.71 (0.06-1.36) P < 0.05) were significantly stronger compared with the other groups. Body fat% was greater in master endurance athletes than young endurance trained (-4.44% (-8.44 to -0.43) P < 0.05) but lower compared with older controls (7.11% (5.70-8.52) P < 0.01).

CONCLUSION

Despite advancing age, this review suggests that chronic exercise training preserves physical function, muscular strength and body fat levels similar to that of young, healthy individuals in an exercise mode-specific manner.

3D bioprinting for cardiovascular regeneration and pharmacology

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Compared to traditional therapeutic strategies, three-dimensional (3D) bioprinting is one of the most advanced techniques for creating complicated cardiovascular implants with biomimetic features, which are capable of recapitulating both the native physiochemical and biomechanical characteristics of the cardiovascular system. The present review provides an overview of the cardiovascular system, as well as describes the principles of, and recent advances in, 3D bioprinting cardiovascular tissues and models. Moreover, this review will focus on the applications of 3D bioprinting technology in cardiovascular repair/regeneration and pharmacological modeling, further discussing current challenges and perspectives.

A regulated multiscale closed-loop cardiovascular model, with applications to hemorrhage and hypertension

A computational tool is developed for simulating the dynamic response of the human cardiovascular system to various stressors and injuries. The tool couples 0-dimensional models of the heart, pulmonary vasculature, and peripheral vasculature to 1-dimensional models of the major systemic arteries. To simulate autonomic response, this multiscale circulatory model is integrated with a feedback model of the baroreflex, allowing control of heart rate, cardiac contractility, and peripheral impedance. The performance of the tool is demonstrated in 2 scenarios: neurogenic hypertension by sustained stimulation of the sympathetic nervous system and an acute 10% hemorrhage from the left femoral artery.

Daily muscle stretching enhances blood flow, endothelial function, capillarity, vascular volume and connectivity in aged skeletal muscle

KEY POINTS

In aged rats, daily muscle stretching increases blood flow to skeletal muscle during exercise. Daily muscle stretching enhanced endothelium-dependent vasodilatation of skeletal muscle resistance arterioles of aged rats. Angiogenic markers and capillarity increased in response to daily stretching in muscles of aged rats. Muscle stretching performed with a splint could provide a feasible means of improving muscle blood flow and function in elderly patients who cannot perform regular aerobic exercise.

ABSTRACT

Mechanical stretch stimuli alter the morphology and function of cultured endothelial cells; however, little is known about the effects of daily muscle stretching on adaptations of endothelial function and muscle blood flow. The present study aimed to determine the effects of daily muscle stretching on endothelium-dependent vasodilatation and muscle blood flow in aged rats. The lower hindlimb muscles of aged Fischer rats were passively stretched by placing an ankle dorsiflexion splint for 30 min day^-1 , 5 days week^-1 , for 4 weeks. Blood flow to the stretched limb and the non-stretched contralateral limb was determined at rest and during treadmill exercise. Endothelium-dependent/independent vasodilatation was evaluated in soleus muscle arterioles. Levels of hypoxia-induced factor-1α, vascular endothelial growth factor A and neuronal nitric oxide synthase were determined in soleus muscle fibres. Levels of endothelial nitric oxide synthase and superoxide dismutase were determined in soleus muscle arterioles, and microvascular volume and capillarity were evaluated by microcomputed tomography and lectin staining, respectively. During exercise, blood flow to plantar flexor muscles was significantly higher in the stretched limb. Endothelium-dependent vasodilatation was enhanced in arterioles from the soleus muscle from the stretched limb. Microvascular volume, number of capillaries per muscle fibre, and levels of hypoxia-induced factor-1α, vascular endothelial growth factor and endothelial nitric oxide synthase were significantly higher in the stretched limb. These results indicate that daily passive stretching of muscle enhances endothelium-dependent vasodilatation and induces angiogenesis. These microvascular adaptations may contribute to increased muscle blood flow during exercise in muscles that have undergone daily passive stretch.

Cardiorespiratory responses and myocardial function within incremental exercise in healthy unmedicated older vs. young men and women

BACKGROUND

Age-related differences concerning cardiorespiratory responses and myocardial function during exercise have not been extensively investigated in healthy populations.

AIMS

To compare cardiorespiratory performance and myocardial function during maximal exercise in healthy/unmedicated men (older, n = 24, 63-75 years; young, n = 22, 19-25 years) and women (older, n = 18, age = 63-74 years; young, n = 23, 19-25 years).

METHODS

Oxygen uptake (VO₂), ventilation minute (V _E), heart rate (HR), stroke volume (SV), cardiac output (Q), O₂ pulse (O₂p), preejection period (PEP), and left ventricular ejection time (LVET) were assessed during cycle incremental exercise.

RESULTS

HR and SV remained equivalent between age groups until 75 and 50% peak workload, respectively. Q increased by 2.5 and 4.5 times in older and young groups, respectively. However, Q/VO₂ ratio was always similar across age and sex groups (∼0.50). The energetic efficiency ratio (W/VO₂) was also alike in older and young men, but slightly lower in women. At maximal exercise, cardiorespiratory responses were lower in older than young men and women: VO₂ (-40 to 50%), V _E (-35 to 37%), HR (-23%), SV (-26 to 29%), Q (-43 to 45%), and O₂p (-15 to 20%). Cardiac and SV indices were lower in older than young groups by approximately 42 and 25%, respectively. LVET was longer in the older individuals, while PEP was similar across age groups. Hence, PEP/LVET was lowered among older vs. young men and women.

CONCLUSION

Submaximal work capacity was preserved in healthy and unmedicated older individuals. Age-related lessening of maximal performance in both sexes was due to poor chronotropic and, particularly, inotropic properties of the heart.

Responsiveness of Noninvasive Continuous Cardiac Output Monitoring During the Valsalva Maneuver

To describe the baseline hemodynamic variables and response time of hemodynamic changes associated with the Valsalva maneuver using noninvasive continuous cardiac output monitoring (Nexfin). Hemodynamic monitoring provides an integral component of advanced clinical care and the ability to monitor response to treatment interventions. The emergence of noninvasive hemodynamic monitoring provides clinicians with an opportunity to monitor and assess patients rapidly with ease of implementation. However, the responsiveness of this method in tracking dynamic changes that occur has not been fully elucidated. A prospective observational study was conducted involving 44 healthy volunteers (age = 38 ±12 years). Participants performed a Valsalva maneuvers to illicit dynamic changes in blood pressure, cardiac output, cardiac index, systemic vascular resistance index (SVRI), and stroke volume. Changes in these hemodynamic parameters were monitored while performing repeated standardized Valsalva maneuvers. Baseline hemodynamic values were obtained in all 44 participants, and showed an interaction with age, accompanying a significant decline in cardiac index (r = -.66, p < .05) and stroke volume (r = -.68,p < .05), and an increase in SVRI (r = .67, p < .05) with increasing age. The Valsalva maneuver, performed in 20 participants, resulted in a change of 10% from baseline blood pressure and cardiac index, which was detected within 4.53 s (SD = 4.36) and 3.31 s (SD = 2.21), respectively. Noninvasive continuous cardiac monitoring demonstrated the ability to rapidly detect logical and predictable hemodynamic changes. These observations suggest that such Nexfin technology may have useful clinical applications.

The Impact of Aging on Cardio and Cerebrovascular Diseases

A growing number of evidences report that aging represents the major risk factor for the development of cardio and cerebrovascular diseases. Understanding Aging from a genetic, biochemical and physiological point of view could be helpful to design a better medical approach and to elaborate the best therapeutic strategy to adopt, without neglecting all the risk factors associated with advanced age. Of course, the better way should always be understanding risk-to-benefit ratio, maintenance of independence and reduction of symptoms. Although improvements in treatment of cardiovascular diseases in the elderly population have increased the survival rate, several studies are needed to understand the best management option to improve therapeutic outcomes. The aim of this review is to give a 360° panorama on what goes on in the fragile ecosystem of elderly, why it happens and what we can do, right now, with the tools at our disposal to slow down aging, until new discoveries on aging, cardio and cerebrovascular diseases are at hand.

Effects of strict prolonged bed rest on cardiorespiratory fitness: systematic review and meta-analysis

The aim of this systematic review and meta-analysis [International Prospective Register of Systematic Reviews (PROSPERO) CRD42017055619] was to assess the effects of strict prolonged bed rest (without countermeasures) on maximal oxygen uptake (V̇o2max) and to explore sources of variation therein. Since 1949, 80 studies with a total of 949 participants (>90% men) have been published with data on strict bed rest and V̇o2max. The studies were conducted mainly in young participants [median age (interquartile range) 24.5 (22.4–34.0) yr]. The duration of bed rest ranged from 1 to 90 days. V̇o2max declined linearly across bed rest duration. No statistical difference in the decline among studies reporting V̇o2max as l/min (−0.3% per day) compared with studies reporting V̇o2max normalized to body weight (ml·kg−1·min−1; −0.43% per day) was observed. Although both total body weight and lean body mass declined in response to bed rest, we did not see any associations with the decline in V̇o2max. However, 15–26% of the variation in the decline in V̇o2max was explained by the pre-bed-rest V̇o2max levels, independent of the duration of bed rest (i.e., higher pre-bed-rest V̇o2max levels were associated with larger declines in V̇o2max). Furthermore, the systematic review revealed a gap in the knowledge about the cardiovascular response to extreme physical inactivity, particularly in older subjects and women of any age group. In addition to its relevance to spaceflight, this lack of data has significant translational implications because younger women sometimes undergo prolonged periods of bed rest associated with the complications of pregnancy and the incidence of hospitalization including prolonged periods of bed rest increases with age.

NEW & NOTEWORTHY Large interindividual responses of maximal oxygen uptake (V̇o2max) to aerobic exercise training exist. However, less is known about the variability in the response of V̇o2max to prolonged bed rest. This systematic review and meta-analysis showed that pre-bed-rest V̇o2max values were inversely associated with the change in V̇o2max independent of the duration of bed rest. Moreover, we identified a large knowledge gap about the causes of decline in V̇o2max, particularly in postmenopausal women, which may have clinical implications.

Biochemical and biomechanical properties of the pacemaking sinoatrial node extracellular matrix are distinct from contractile left ventricular matrix

Extracellular matrix plays a role in differentiation and phenotype development of its resident cells. Although cardiac extracellular matrix from the contractile tissues has been studied and utilized in tissue engineering, extracellular matrix properties of the pacemaking sinoatrial node are largely unknown. In this study, the biomechanical properties and biochemical composition and distribution of extracellular matrix in the sinoatrial node were investigated relative to the left ventricle. Extracellular matrix of the sinoatrial node was found to be overall stiffer than that of the left ventricle and highly heterogeneous with interstitial regions composed of predominantly fibrillar collagens and rich in elastin. The extracellular matrix protein distribution suggests that resident pacemaking cardiomyocytes are enclosed in fibrillar collagens that can withstand greater tensile strength while the surrounding elastin-rich regions may undergo deformation to reduce the mechanical strain in these cells. Moreover, basement membrane-associated adhesion proteins that are ligands for integrins were of low abundance in the sinoatrial node, which may decrease force transduction in the pacemaking cardiomyocytes. In contrast to extracellular matrix of the left ventricle, extracellular matrix of the sinoatrial node may reduce mechanical strain and force transduction in pacemaking cardiomyocytes. These findings provide the criteria for a suitable matrix scaffold for engineering biopacemakers.

Assessment of a noninvasive optical photoplethysmography imaging device with dynamic tissue phantom models

Noncontact photoplethysmography (PPG) has been studied as a method to provide low-cost, noninvasive, two-dimensional blood oxygenation measurements and medical imaging for a variety of near-surface pathologies. To evaluate this technology in a laboratory setting, dynamic tissue phantoms were developed with tunable parameters that mimic physiologic properties of the skin, including blood vessel volume change, pulse wave frequency, and tissue scattering and absorption. Tissue phantoms were generated using an elastic tubing to represent a blood vessel where the luminal volume could be modulated with a pulsatile fluid flow. The blood was mimicked with a scattering and absorbing motility standard, and the tissue with a gelatin-lipid emulsion hydrogel. A noncontact PPG imaging system was then evaluated using the phantoms. Noncontact PPG imaging accurately identified pulse frequency, and PPG signals from these phantoms suggest that the phantoms can be used to evaluate noncontact PPG imaging systems. Such information may be valuable to the development of future PPG imaging systems.

Distribution of cardiac output to the brain across the adult lifespan

A widely accepted dogma is that about 15-20% of cardiac output is received by the brain in healthy adults under resting conditions. However, it is unclear if the distribution of cardiac output directed to the brain alters across the adult lifespan and is modulated by sex or other hemodynamic variables. We measured cerebral blood flow/cardiac output ratio index in 139 subjects (88 women, age 21-80 years) using phase-contrast magnetic resonance imaging and echocardiography. Body mass index, cardiac systolic function (eject fraction), central arterial stiffness (carotid-femoral pulse wave velocity), arterial pressure, heart rate, physical fitness (VO2 max), and total brain volume were measured to assess their effects on the cardiac output-cerebral blood flow relationship. Cerebral blood flow/cardiac output ratio index decreased by 1.3% per decade associated with decreases in cerebral blood flow ( P < 0.001), while cardiac output remained unchanged. Women had higher cerebral blood flow, lower cardiac output, and thus higher cerebral blood flow/cardiac output ratio index than men across the adult lifespan. Age, body mass index, carotid-femoral pulse wave velocity, and arterial pressure all had negative correlations with cerebral blood flow and cerebral blood flow/cardiac output ratio index ( P < 0.05). Multivariable analysis adjusted for sex, age showed that only body mass index was negatively associated with cerebral blood flow/cardiac output ratio index (β = -0.33, P < 0.001). These findings demonstrated that cardiac output distributed to the brain has sex differences and decreases across the adult lifespan and is inversely associated with body mass index.

Dynamic bicycle exercise to assess cardiac output at multiple exercise levels during magnetic resonance imaging

PURPOSE

The aim was to establish a method for performing dynamic exercise during magnetic resonance imaging (MRI) using a slowly increasing workload protocol.

METHODS

An ergometer bicycle with a step-wise, exercise protocol was used. Real-time phase-contrast MRI images of the aorta were obtained at each exercise step.

RESULTS

In total, 40 participants completed the exercise protocol to reach a mean maximum cardiac output of 13.7±3.7l/min and a heart rate of 150±16beats/min at the highest exercise level. Less than 1% of scans were discarded due to poor quality.

CONCLUSIONS

Dynamic, high intensity exercise is feasible during MRI.

Chlorhexidine and silver sulfadiazine coating on central venous catheters is not sufficient for protection against catheter-related infection: Simulation-based laboratory research with clinical validation

Objective The efficacy of chlorhexidine- and silver sulfadiazine-coated central venous catheters (CSS-CVC) against catheter-related infection remains controversial. We hypothesized that the loss of silver nanoparticles may reduce the antibacterial efficacy of CSS-CVCs and that this loss could be due to the frictional force between the surface of the CVC and the bloodstream. The objective of this study was to investigate whether the antimicrobial effect of CSS-CVCs decreases with increasing exposure time in a bloodstream model and quantitatively assay the antimicrobial effect of CSS-CVCs compared with polyurethane and antiseptic-impregnated CVCs. Methods Each CVC was subjected to 120 hours of saline flow and analyzed at intervals over 24 hours. The analyses included energy-dispersive X-ray spectroscopy, scanning electron microscopy, and optical density after a Staphylococcus aureus incubation test. Results The weight percentage of silver in the CSS-CVCs significantly decreased to 56.18% (44.10% ± 3.32%) with 48-hour catheterization and to 18.88% (14.82% ± 1.33%) with 120-hour catheterization compared with the initial weight percentage (78.50% ± 6.32%). In the S. aureus incubation test, the antibacterial function of CSS-CVCs was lost after 48 hours [3 (N/D) of OD]. Similar results were observed in a pilot clinical study using 18 CSS-CVCs. Conclusions We found that the efficacy of CSS-CVCs decreased over time and that the antibacterial function was lost after 48 hours of simulated wear-out. Therefore, antibiotic-impregnated CVCs may be a better option when longer (>48 hours) indwelling is needed.

Sympathetic neural and cardiovascular responses during static handgrip exercise in women with a history of hypertensive pregnancy

PURPOSE

Women with a history of hypertensive pregnancy are at greater risk for future cardiovascular events; however, the mechanisms for this increased risk are unknown. Evidence suggests that an exercise stimulus unmasks latent hypertensive tendencies, identifying individuals at the greatest risk for developing cardiovascular disease. The current study examined the hypothesis that women with a hypertensive pregnancy history exhibit an augmented exercise pressor response.

METHODS

Normotensive women with a history of healthy pregnancy (CON; n = 9) and hypertensive pregnancy (HP+; n = 12) were studied during the mid-luteal phase of the menstrual cycle. Heart rate (HR), systolic and diastolic blood pressure (SBP, DBP), and muscle sympathetic nerve activity (MSNA) were measured during a cold pressor test (CPT), and, following a sufficient period of recovery, during static handgrip to fatigue (SHG) and post-exercise circulatory arrest (PECA).

RESULTS

The BP, HR, and MSNA responses to the CPT were similar between groups. The SBP response to SHG and PECA was similar between groups, but DBP and HR were significantly greater in HP+ women (both p < 0.05). MSNA burst frequency, but not burst incidence or total activity, tended to be elevated in HP+ women during the stressor (peak Δ from baseline 31 ± 13 vs. 23 ± 13 bursts/min; p for group = 0.06).

CONCLUSION

Despite no clinical signs of cardiovascular disease or hypertension, women with a history of hypertensive pregnancy display an enhanced cardiovascular reactivity to an exercise stimulus compared to women with a healthy pregnancy history. This response may be indicative of impaired cardiovascular control that precedes the clinical manifestation of hypertension or cardiovascular events.

The Role of Exercise in Cardiac Aging: From Physiology to Molecular Mechanisms

Aging induces structural and functional changes in the heart that are associated with increased risk of cardiovascular disease and impaired functional capacity in the elderly. Exercise is a diagnostic and therapeutic tool, with the potential to provide insights into clinical diagnosis and prognosis, as well as the molecular mechanisms by which aging influences cardiac physiology and function. In this review, we first provide an overview of how aging impacts the cardiac response to exercise, and the implications this has for functional capacity in older adults. We then review the underlying molecular mechanisms by which cardiac aging contributes to exercise intolerance, and conversely how exercise training can potentially modulate aging phenotypes in the heart. Finally, we highlight the potential use of these exercise models to complement models of disease in efforts to uncover new therapeutic targets to prevent or treat heart disease in the aging population.

Right Ventricular Functional Reserve in Pulmonary Arterial Hypertension

BACKGROUND

Right ventricular (RV) functional reserve affects functional capacity and prognosis in patients with pulmonary arterial hypertension (PAH). PAH associated with systemic sclerosis (SSc-PAH) has a substantially worse prognosis than idiopathic PAH (IPAH), even though many measures of resting RV function and pulmonary vascular load are similar. We therefore tested the hypothesis that RV functional reserve is depressed in SSc-PAH patients.

METHODS AND RESULTS

RV pressure-volume relations were prospectively measured in IPAH (n=9) and SSc-PAH (n=15) patients at rest and during incremental atrial pacing or supine bicycle ergometry. Systolic and lusitropic function increased at faster heart rates in IPAH patients, but were markedly blunted in SSc-PAH. The recirculation fraction, which indexes intracellular calcium recycling, was also depressed in SSc-PAH (0.32±0.05 versus 0.50±0.05; P=0.039). At matched exercise (25 W), SSc-PAH patients did not augment contractility (end-systolic elastance) whereas IPAH did (P<0.001). RV afterload assessed by effective arterial elastance rose similarly in both groups; thus, ventricular-vascular coupling declined in SSc-PAH. Both end-systolic and end-diastolic RV volumes increased in SSc-PAH patients to offset contractile deficits, whereas chamber dilation was absent in IPAH (+37±10% versus +1±8%, P=0.004, and +19±4% versus -1±6%, P<0.001, respectively). Exercise-associated RV dilation also strongly correlated with resting ventricular-vascular coupling in a larger cohort.

CONCLUSIONS

RV contractile reserve is depressed in SSc-PAH versus IPAH subjects, associated with reduced calcium recycling. During exercise, this results in ventricular-pulmonary vascular uncoupling and acute RV dilation. RV dilation during exercise can predict adverse ventricular-vascular coupling in PAH patients.

The aging influence on cardiorespiratory, metabolic, and energy expenditure adaptations in head-out aquatic exercises: Differences between young and elderly women

The purpose of this study was to: (1) establish the relationship between acute physiological responses and musical cadence; and (2) compare physiologic responses between young and older women. Eighteen older (mean = 65.06 ± 5.77 years) and 19 young (mean = 22.16 ± 2.63 years) women underwent an intermittent and progressive protocol performing the head-out aquatic exercise the "rocking horse." Results showed that older women demonstrated lower mean heart rate, blood lactate concentration (bLa), and oxygen uptake (VO₂) at rest. Hierarchical linear modeling showed that variations in the rating of perceived effort and individual metabolic equivalent of task did not differ significantly by age group. However, during exercise, physiological responses of younger women were significantly different than for older women: in mean values, for each increased musical beat per minute, mean bLa was 0.003 mmol/l, VO₂ was 0.024 ml/kg/min, and energy expenditure was 0.0001 kcal/kg/min higher for younger women. This study shows that increases in musical cadence increased the cardiorespiratory, metabolic, and energy expenditure responses. However, these responses during increasing intensity seemed to differ between young and older women, with lower values for the elderly group, when performing head-out aquatic exercises.

Altered left ventricular performance in aging physically active mice with an ankle sprain injury

We assessed the impact of differing physical activity levels throughout the lifespan, using a musculoskeletal injury model, on the age-related changes in left ventricular (LV) parameters in active mice. Forty male mice (CBA/J) were randomly placed into one of three running wheel groups (transected CFL group, transected ATFL/CFL group, SHAM group) or a SHAM Sedentary group (SHAMSED). Before surgery and every 6 weeks after surgery, LV parameters were measured under 2.5 % isoflurane inhalation. Group effects for daily distance run was significantly greater for the SHAM and lesser for the ATLF/CFL mice (p = 0.013) with distance run decreasing with age for all mice (p < 0.0001). Beginning at 6 months of age, interaction (group × age) was noted with LV posterior wall thickness-to-radius ratios (h/r) where h/r increased with age in the ATFL/CFL and SHAMSED mice while the SHAM and CFL mice exhibited decreased h/r with age (p = 0.0002). Passive filling velocity (E wave) was significantly greater in the SHAM mice and lowest for the ATFL/CFL and SHAMSED mice (p < 0.0001) beginning at 9 months of age. Active filling velocity (A wave) was not different between groups (p = 0.10). Passive-to-active filling velocity ratio (E/A ratio) was different between groups (p < 0.0001), with higher ratios for the SHAM mice and lower ratios for the ATFL/CFL and SHAMSED mice in response to physical activity beginning at 9 months of age. Passive-to-active filling velocity ratio decreased with age (p < 0.0001). Regular physical activity throughout the lifespan improved LV structure, passive filling velocity, and E/A ratio by 6 to 9 months of age and attenuated any negative alterations throughout the second half of life. The diastolic filling differences were found to be significantly related to the amount of activity performed by 9 months and at the end of the lifespan.

Adverse Left Ventricular Remodeling and Age Assessed with Cardiac MR Imaging: The Multi-Ethnic Study of Atherosclerosis

PURPOSE

To evaluate age-related left ventricular (LV) remodeling during longitudinal observation of a large cohort of asymptomatic individuals who were free of clinical cardiovascular disease at baseline.

MATERIALS AND METHODS

The applicable institutional review boards approved this study, and all participants gave informed consent. Cardiac magnetic resonance (MR) imaging was used to identify longitudinal changes in LV structure and function in 2935 participants who underwent baseline and follow-up cardiac MR imaging in the Multi-Ethnic Study of Atherosclerosis. Participants were free of clinical cardiovascular disease at baseline. Participants who experienced an incident coronary heart disease event were excluded. Data were analyzed with multivariable mixed-effects regression models in which the outcome was cardiac MR imaging measurement, and the covariates included follow-up time and cardiac risk factors.

RESULTS

Participants were aged 54-94 years at follow-up, and 53% of the participants were women. Median time between baseline and follow-up cardiac MR imaging was 9.4 years. Over this period, LV mass increased in men and decreased slightly in women (8.0 and -1.6 g per decade, respectively; P < .001). In both men and women, LV end-diastolic volume decreased (-9.8 and -13.3 mL per decade, respectively; P < .001), stroke volume decreased (-8.8 and -8.6 mL per decade, respectively; P < .001), and mass-to-volume ratio increased (0.14 and 0.11 g/mL per decade, respectively; P < .001). Change in LV mass was positively associated with systolic blood pressure and body mass index and negatively associated with treated hypertension and high-density lipoprotein cholesterol level. In men, the longitudinal LV mass increase was in contrast to a cross-sectional pattern of LV mass decrease.

CONCLUSION

As patients age, the LV responds differently in its mass and volume between men and women, although both men and women experience increased concentric LV remodeling with age. In men, the opposition of longitudinal and cross-sectional changes in LV mass highlights the importance of longitudinal study.