Heart failure with preserved ejection fraction in older adults

Adult Cardiac Stem Cell Aging: A Reversible Stochastic Phenomenon?

Aging is by far the dominant risk factor for the development of cardiovascular diseases, whose prevalence dramatically increases with increasing age reaching epidemic proportions. In the elderly, pathologic cellular and molecular changes in cardiac tissue homeostasis and response to injury result in progressive deteriorations in the structure and function of the heart. Although the phenotypes of cardiac aging have been the subject of intense study, the recent discovery that cardiac homeostasis during mammalian lifespan is maintained and regulated by regenerative events associated with endogenous cardiac stem cell (CSC) activation has produced a crucial reconsideration of the biology of the adult and aged mammalian myocardium. The classical notion of the adult heart as a static organ, in terms of cell turnover and renewal, has now been replaced by a dynamic model in which cardiac cells continuously die and are then replaced by CSC progeny differentiation. However, CSCs are not immortal. They undergo cellular senescence characterized by increased ROS production and oxidative stress and loss of telomere/telomerase integrity in response to a variety of physiological and pathological demands with aging. Nevertheless, the old myocardium preserves an endogenous functionally competent CSC cohort which appears to be resistant to the senescent phenotype occurring with aging. The latter envisions the phenomenon of CSC ageing as a result of a stochastic and therefore reversible cell autonomous process. However, CSC aging could be a programmed cell cycle-dependent process, which affects all or most of the endogenous CSC population. The latter would infer that the loss of CSC regenerative capacity with aging is an inevitable phenomenon that cannot be rescued by stimulating their growth, which would only speed their progressive exhaustion. The resolution of these two biological views will be crucial to design and develop effective CSC-based interventions to counteract cardiac aging not only improving health span of the elderly but also extending lifespan by delaying cardiovascular disease-related deaths.

Molecular and genetic aspects of guanylyl cyclase natriuretic peptide receptor-A in regulation of blood pressure and renal function

Natriuretic peptides (NPs) exert diverse effects on several biological and physiological systems, such as kidney function, neural and endocrine signaling, energy metabolism, and cardiovascular function, playing pivotal roles in the regulation of blood pressure (BP) and cardiac and vascular homeostasis. NPs are collectively known as anti-hypertensive hormones and their main functions are directed toward eliciting natriuretic/diuretic, vasorelaxant, anti-proliferative, anti-inflammatory, and anti-hypertrophic effects, thereby, regulating the fluid volume, BP, and renal and cardiovascular conditions. Interactions of NPs with their cognate receptors display a central role in all aspects of cellular, biochemical, and molecular mechanisms that govern physiology and pathophysiology of BP and cardiovascular events. Among the NPs atrial and brain natriuretic peptides (ANP and BNP) activate guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) and initiate intracellular signaling. The genetic disruption of Npr1 (encoding GC-A/NPRA) in mice exhibits high BP and hypertensive heart disease that is seen in untreated hypertensive subjects, including high BP and heart failure. There has been a surge of interest in the NPs and their receptors and a wealth of information have emerged in the last four decades, including molecular structure, signaling mechanisms, altered phenotypic characterization of transgenic and gene-targeted animal models, and genetic analyses in humans. The major goal of the present review is to emphasize and summarize the critical findings and recent discoveries regarding the molecular and genetic regulation of NPs, physiological metabolic functions, and the signaling of receptor GC-A/NPRA with emphasis on the BP regulation and renal and cardiovascular disorders.

Hypertension-induced remodelling: on the interactions of cardiac risk factors

Hypertension induces considerable cardiac remodelling, such as hypertrophy, interstitial fibrosis, and abnormal activity of the cardiac sympathetic nervous system, which are established risk factors in several highly dangerous heart diseases, such as ventricular fibrillation and congestive heart failure. All these risk factors and heart diseases are studied extensively in isolation, but to our knowledge, there is no comprehensive review of their interactions. At the same time, there is growing evidence suggesting that such interactions are numerous and that a successful therapy against a particular condition may have unexpectedly weak effects on mortality, as treated patients may die of a different cause exacerbated by the therapy. In this article, we present a multiscale review of the literature focusing on the relationships between the above‐mentioned risk factors and heart diseases, and introduce a framework that gives insight into their possible interactions. We use this framework to demonstrate that conditions such as fibrosis and elevated activity of the sympathetic nervous system may be compensatory, rather than purely pathological, mechanisms in certain contexts. Finally, we show why the described mechanisms are relevant not only in hypertension, but also in the case of healed myocardial infarction.

Epicardial adipose tissue is related to cardiac function in elderly women, but not in men

BACKGROUND AND AIM

Epicardial adipose tissue (EAT) is easily quantifiable visceral adipose tissue that is closely associated with cardiometabolic disease including heart failure with preserved left ventricular (LV) ejection fraction. As body fat distribution and metabolism are different between men and women, we evaluated the sex difference in EAT thickness and its relationship to cardiac function.

METHODS AND RESULTS

A total of 152 consecutive patients (76 men) with mean age of 62 ± 9 years were enrolled. Conventional echocardiography was performed and EAT thickness was measured perpendicularly on the right ventricular free wall at end systole. Mean EAT thickness in all patients was 6.5 ± 2.0 mm. EAT thickness was associated with patient age, body mass index, and the presence of hypertension. EAT thickness was not different by sex in patients younger than 60 years (men, 6.4 ± 2.0 mm; women, 6.2 ± 1.8 mm, p = 0.716); however, among patients aged 60 years or older, EAT thickness was significantly greater in women than men (men, 6.0 ± 1.7 mm; women 7.7 ± 2.1 mm, p < 0.001). LV function represented by E/e' and s' was significantly related to EAT thickness only in women (E/e', β = 0.330, p = 0.002; lateral s', β = -0.225, p = 0.042).

CONCLUSION

EAT thickness was greater in women than men after 60 years old and its relationship with LV function was significant only in women. Greater increase in EAT thickness in elderly women after menopause might partially account for this difference.

Structural remodeling of coronary resistance arteries: effects of age and exercise training

Age is known to induce remodeling and stiffening of large-conduit arteries; however, little is known of the effects of age on remodeling and mechanical properties of coronary resistance arteries. We employed a rat model of aging to investigate whether 1) age increases wall thickness and stiffness of coronary resistance arteries, and 2) exercise training reverses putative age-induced increases in wall thickness and stiffness of coronary resistance arteries. Young (4 mo) and old (21 mo) Fischer 344 rats remained sedentary or underwent 10 wk of treadmill exercise training. Coronary resistance arteries were isolated for determination of wall-to-lumen ratio, effective elastic modulus, and active and passive responses to changes in intraluminal pressure. Elastin and collagen content of the vascular wall were assessed histologically. Wall-to-lumen ratio increased with age, but this increase was reversed by exercise training. In contrast, age reduced stiffness, and exercise training increased stiffness in coronary resistance arteries from old rats. Myogenic responsiveness was reduced with age and restored by exercise training. Collagen-to-elastin ratio (C/E) of the wall did not change with age and was reduced with exercise training in arteries from old rats. Thus age induces hypertrophic remodeling of the vessel wall and reduces the stiffness and myogenic function of coronary resistance arteries. Exercise training reduces wall-to-lumen ratio, increases wall stiffness, and restores myogenic function in aged coronary resistance arteries. The restorative effect of exercise training on myogenic function of coronary resistance arteries may be due to both changes in vascular smooth muscle phenotype and expression of extracellular matrix proteins.

Diverse geometric changes related to dynamic left ventricular outflow tract obstruction without overt hypertrophic cardiomyopathy

BACKGROUND

Dynamic left ventricular (LV) outflow tract (LVOT) obstruction (DLVOTO) is not infrequently observed in older individuals without overt hypertrophic cardiomyopathy (HCM). We sought to investigate associated geometric changes and then evaluate their clinical characteristics.

METHODS

A total of 168 patients with DLVOTO, which was defined as a trans-LVOT peak pressure gradient (PG) higher than 30 mmHg at rest or provoked by Valsalva maneuver (latent LVOTO) without fixed stenosis, were studied. Patients with classical HCM, acute myocardial infarction, stress induced cardiomyopathy or unstable hemodynamics which potentially induce transient-DLVOTO were excluded.

RESULTS

Their mean age was 71 ± 11 years and 98 (58%) patients were women. Patients were classified as pure sigmoid septum (n = 14) if they have basal septal bulging but diastolic thickness less than 15 mm, sigmoid septum with basal septal hypertrophy for a thickness ≥15 mm (n = 85), prominent papillary muscle (PM) (n = 20) defined by visually large PMs which occluded the LV cavity during systole or 1/2 LVESD, or as having a small LV cavity with concentric remodelling or hypertrophy (n = 49). The prominent PM group was younger, had a higher S' and lower E/e' than other groups. In all groups, a higher peak trans-LVOT PG was related (p < 0.10) to higher E/e', systolic blood pressure, relative wall thickness, and pulmonary arterial systolic pressure. In multivariate analysis, resting trans-LVOT PG correlated to pulmonary arterial pressure (ß = 0.226, p = 0.019) after adjustment for systolic blood pressure, relative wall thickness, and E/e'.

CONCLUSIONS

DLVOTO develops from various reasons, and patients with prominent PMs have distinct characteristics. We suggest to use DLVOTO-relieving medication might reduce pulmonary pressure in this group of patients.

Characterization of echocardiographic measures of cardiac structure and function in healthy octogenarians

BACKGROUND

Currently, there is not enough echocardiographic information regarding aging-associated changes in the octogenarian population. We aimed to characterize echocardiographic measures of structure and function among a group of healthy octogenarians.

METHODS

Approximately 350 octogenarians, residing in nursing homes, were screened in Ankara, Turkey. According to inclusion criteria, 40 octogenarians were enrolled. These subjects underwent conventional and tissue Doppler echocardiography according to the guidelines of the American Society of Echocardiography (ASE). The population was also separated into various groups according to gender, body mass index (BMI, <25 vs. 25-29.9), and blood pressure (<80/120 mmHg vs. 80-89/120-139 mmHg). All measurements were indexed by dividing to body surface area (BSA) for standardization.

RESULTS

Left ventricular mass (LVM), posterior wall thickness, right ventricular diameter, tricuspid E/A ratio, and septal e'-wave velocity were significantly higher in men, which lost significance after adjusting for BSA. There was no significant difference between groups formed by BMI and blood pressure. Moreover, mild global left and right ventricular dysfunction including a prominent diastolic counterpart, however, with normal ejection fraction was revealed using conventional and tissue Doppler techniques. Finally, we checked our results with the current reference values of the ASE and observed the following differences: ventricular septum, relative wall thickness, LVM, and mass index values were above ASE reference range, posterior wall measurements were close to upper range. On the contrary, left ventricular diameters and volumes were below ASE reference range.

CONCLUSIONS

We described echocardiographic measures of structure and function in a group of healthy octogenarians.

The role of inflammatory and fibrogenic pathways in heart failure associated with aging

Heart failure is strongly associated with aging. Elderly patients with heart failure often have preserved systolic function exhibiting left ventricular hypertrophy accompanied by a decline in diastolic function. Experimental studies have demonstrated that age-related cardiac fibrosis plays an important role in the pathogenesis of diastolic heart failure in senescent hearts. Reactive oxygen species and angiotensin II are critically involved in fibrotic remodeling of the aging ventricle; their fibrogenic actions may be mediated, at least in part, through transforming growth factor (TGF)-beta. The increased prevalence of heart failure in the elderly is also due to impaired responses of the senescent heart to cardiac injury. Aging is associated with suppressed inflammation, delayed phagocytosis of dead cardiomyocytes, and markedly diminished collagen deposition following myocardial infarction, due to a blunted response of fibroblasts to fibrogenic growth factors. Thus, in addition to a baseline activation of fibrogenic pathways, senescent hearts exhibit an impaired reparative reserve due to decreased responses of mesenchymal cells to stimulatory signals. Impaired scar formation in senescent hearts is associated with accentuated dilative remodeling and worse systolic dysfunction. Understanding the pathogenesis of interstitial fibrosis in the aging heart and dissecting the mechanisms responsible for age-associated healing defects following cardiac injury are critical in order to design new strategies for prevention of adverse remodeling and heart failure in elderly patients.

Decreased cardiac functional reserve in heart failure with preserved systolic function

BACKGROUND

Heart failure in patients with preserved left ventricular systolic function (HFpEF) is a prevalent disease characterized by exercise intolerance with poorly understood pathophysiology. We hypothesized that recruitable contractility is impaired in HFpEF, accounting for the appearance of symptoms with exertion.

METHODS AND RESULTS

Echocardiographic analysis of myocardial performance was performed at baseline and after a modified dobutamine protocol (max dose 16 μg/kg/min) in participants with known HFpEF and age- and gender-matched controls. The primary outcome variable was change in contractile reserve, measured as a change in ejection fraction (EF). Recruitable contractility was decreased in HFpEF participants compared with control subjects (HFpEF 0.4 ± 1.9% vs control 19.0 ± 1.4%; P < .001). During dobutamine infusion, velocities increased in control participants but remained unchanged in the HFpEF group, yielding a significant difference between groups (P < .05) for both longitudinal displacement and velocity.

CONCLUSIONS

Patients with HFpEF have an impaired contractile response to adrenergic stimulation. The blunted response to adrenergic stimulation in the HFpEF group suggests that these patients may be unable to respond to periods of increased cardiac demand. This inability to increase contractility appropriately suggests abnormalities of systolic function in this disease and may contribute to exertional intolerance in HFpEF.