Vibrational spectroscopy identifies myocardial chemical modifications in heart failure with preserved ejection fraction.

BACKGROUND: Vibrational spectroscopy can be a valuable tool to monitor the markers of cardiovascular diseases. In the present work, we explored the vibrational spectroscopy characteristics of the cardiac tissue in an experimental model of heart failure with preserved ejection fraction (HFpEF). The goal was to detect early cardiac chemical modifications associated with the development of HFpEF. METHODS: We used the Fourier-transform infrared (FTIR) and Raman micro-spectroscopic techniques to provide complementary and objective tools for the histological assessment of heart tissues from an animal model of HFpEF. A new sampling technique was adopted (tissue print on a CaF2 disk) to characterize the extracellular matrix. RESULTS: Several spectroscopic markers (lipids, carbohydrates, and glutamate bands) were recognized in the cardiac ventricles due to the comorbidities associated with the pathology, such as obesity and diabetes. Besides, abnormal collagen cross-linking and a decrease in tryptophan content were observed and related to the stiffening of ventricles and to the inflammatory state which is a favourable condition for HFpEF. CONCLUSIONS: By the analyses of tissues and tissue prints, FTIR and Raman techniques were shown to be highly sensitive and selective in detecting changes in the chemistry of the heart in experimental HFpEF and its related comorbidities. Vibrational spectroscopy is a new approach that can identify novel biomarkers for early detection of HFpEF.

FTIR Analysis of Renal Tissue for the Assessment of Hypertensive Organ Damage and proANP31-67 Treatment.

The kidneys are one of the main end organs targeted by hypertensive disease. Although the central role of the kidneys in the regulation of high blood pressure has been long recognized, the detailed mechanisms behind the pathophysiology of renal damage in hypertension remain a matter of investigation. Early renal biochemical alterations due to salt-induced hypertension in Dahl/salt-sensitive rats were monitored by Fourier-Transform Infrared (FTIR) micro-imaging. Furthermore, FTIR was used to investigate the effects of proANP31-67, a linear fragment of pro-atrial natriuretic peptide, on the renal tissue of hypertensive rats. Different hypertension-induced alterations were detected in the renal parenchyma and blood vessels by the combination of FTIR imaging and principal component analysis on specific spectral regions. Changes in amino acids and protein contents observed in renal blood vessels were independent of altered lipid, carbohydrate, and glycoprotein contents in the renal parenchyma. FTIR micro-imaging was found to be a reliable tool for monitoring the remarkable heterogeneity of kidney tissue and its hypertension-induced alterations. In addition, FTIR detected a significant reduction in these hypertension-induced alterations in the kidneys of proANP31-67-treated rats, further indicating the high sensitivity of this cutting-edge imaging modality and the beneficial effects of this novel medication on the kidneys.

Renal sympathetic denervation lowers systemic vascular resistance in true treatment-resistant hypertension.

PURPOSE: Renal sympathetic denervation (RDN) is again gaining interest as recent well-designed trials have demonstrated reduced ambulatory blood pressure (BP) after RDN. However, the hemodynamic mechanisms have not been elucidated. We aimed for the first time to investigate the effect of RDN on the "Hallmark of Hypertension" namely increased systemic vascular resistance index (SVRI). MATERIALS AND METHODS: We investigated SVRI change in patients with true treatment-resistant hypertension randomised to RDN (n = 9) or drug adjusted control (n = 9). Treatment-resistant hypertension was defined as office systolic BP ≥ 140 mmHg despite ≥ 3 antihypertensive drugs including a diuretic. True treatment-resistant hypertension was confirmed prior to inclusion with ambulatory daytime systolic BP ≥ 135 mmHg immediately after witnessed intake of antihypertensive drugs. Hemodynamic variables were recorded with thoracic impedance cardiography at baseline and at three and six months follow-up after RDN. This non-invasive method also guided further tailoring of drug treatment in the control group aiming to normalise hemodynamic variables and BP. RESULTS: From three to six months follow-up after RDN, SVRI decreased with a median of -611 dyn*s*m2/cm5 [IQR -949 to -267] (p < 0.01), while supine mean BP decreased with a median of -11 mmHg [IQR -21 to -3] (p = 0.02). In the same period, SVRI in the control group was reduced with -674 dyn*s*m2/cm5 [IQR -1,309 to -340] (p < 0.01), while supine mean BP decreased with -15 mmHg [IQR -29 to -6] (p = 0.01). Thus, hemodynamic variables and BP in the two groups normalised in parallel. CONCLUSION: Our data suggest that in patients with true treatment-resistant hypertension, renal sympathetic denervation lowers BP by reducing systemic vascular resistance of similar size as in the control group with careful individual selection of antihypertensive drugs and dose titration.

B-type natriuretic peptide overexpression ameliorates hepatorenal fibrocystic disease in a rat model of polycystic kidney disease.

Polycystic kidney disease (PKD) involves progressive hepatorenal cyst expansion and fibrosis, frequently leading to end-stage renal disease. Increased vasopressin and cAMP signaling, dysregulated calcium homeostasis, and hypertension play major roles in PKD progression. The guanylyl cyclase A agonist, B-type natriuretic peptide (BNP), stimulates cGMP and shows anti-fibrotic, anti-hypertensive, and vasopressin-suppressive effects, potentially counteracting PKD pathogenesis. Here, we assessed the impacts of guanylyl cyclase A activation on PKD progression in a rat model of PKD. Sustained BNP production significantly reduced kidney weight, renal cystic indexes and fibrosis, in concert with suppressed hepatic cystogenesis in vivo. In vitro, BNP decreased cystic epithelial cell proliferation, suppressed fibrotic gene expression, and increased intracellular calcium. Together, our data demonstrate multifaceted effects of sustained activation of guanylyl cyclase A on polycystic kidney and liver disease. Thus, targeting the guanylyl cyclase A-cGMP axis may provide a novel therapeutic strategy for hepatorenal fibrocystic diseases.

Serum sodium correction rate and the outcome in severe hyponatremia.

STUDY OBJECTIVE: We investigated the serum sodium correction rate on length of hospitalization and survival rate, in severe chronic hyponatremic patients at the Emergency Department (ED). DESIGN: An observational study using clinical chart review. SETTING: The ED of the University Hospital of Marcianise, Caserta, Italy with approximately 30,000 patients visits a year. TYPE OF PARTICIPANTS: We reviewed sixty-seven patients with severe hyponatremia subdivided in 2 subgroups: group A consisting of 35 patients with serum sodium correction rate<0.3mmol/h and group B consisting of 32 patients with serum sodium correction rate between <0.5 and ≥0.3mmol/h. INTERVENTION: Emergency patients were evaluated for serum sodium correction rate for hyponatremia by clinical chart review. MEASUREMENTS AND MAIN RESULTS: Severe hyponatremia was defined as a serum sodium level<120mmol/l. Mean serum sodium correction rate of hyponatremia was of 0.17±0.09% in group A and 0.41±0.05% in group B (p<0.001 vs group A). The length of hospital stay was 10.7±3.7days for group A, and it was significantly decreased to 3.8±0.4days for group B (p<0.005 vs group A). In addition we observed that correction rate of hyponatremia in group A was associated with a significantly lower survival rate (25%) in comparison to group B (60%) (p<0.001 vs group A). CONCLUSION: We observed that serum sodium correction rate ≥0.3 and <0.5mmol/h was associated with a shorter length of hospital stay and a major survival rate.

Seasonal variations of hyponatremia in the emergency department: Age-related changes.

STUDY OBJECTIVE: We investigated seasonal prevalence of hyponatremia in the emergency department (ED). DESIGN: A cross-sectional study using clinical chart review. SETTING: University Hospital ED, with approximately 28 000 patient visits a year. TYPE OF PARTICIPANTS: We reviewed 15 049 patients, subdivided in 2 groups: the adult group consisting of 9822 patients aged between 18 and 64years old and the elderly group consisting of 5227 patients aged over 65years presenting to the ED between January 1st, 2014 and December 31st, 2015. INTERVENTION: Emergency patients were evaluated for the presence of hyponatremia by clinical chart review. MEASUREMENTS AND MAIN RESULTS: Hyponatremia was defined as a serum sodium level<135mmol/l. Mean monthly prevalence of hyponatremia was of 3.74±0.5% in the adult group and it was significantly increased to 10.3±0.7% in the elderly group (p<0.05 vs adults). During the summer, hyponatremia prevalence was of 4.14±0.2% in adult and markedly increased to 12.52±0.7% (zenith) in elderly patients (p<0.01 vs adult group; p<0.05 vs other seasons in elderly group). In the elderly group, we reported a significant correlation between weather temperature and hyponatremia prevalence (r: 0.491; p<0.05). CONCLUSION: We observed a major influence of climate on the prevalence of hyponatremia in the elderly in the ED. Decline in renal function, salt loss, reduced salt intake and increased water ingestion could all contribute to developing hyponatremia in elderly patients during the summer. These data could be useful for emergency physicians to prevent hot weather-induced hyponatremia in the elderly.

Influence of glycosylation on diagnostic and prognostic accuracy of N-terminal pro-B-type natriuretic peptide in acute dyspnea: data from the Akershus Cardiac Examination 2 Study.

BACKGROUND: The N-terminal part of pro-B-type natriuretic peptide (NT-proBNP) is glycosylated, but whether glycosylation influences the diagnostic and prognostic accuracy of NT-proBNP measurements is not known. METHODS: We measured NT-proBNP concentrations of 309 patients with acute dyspnea by use of standard EDTA tubes and EDTA tubes pretreated with deglycosylation enzymes. The primary cause of dyspnea was classified as heart failure (HF) or non-HF, and the diagnosis was adjudicated by 2 independent physicians. We collected information on all-cause mortality during follow-up. RESULTS: In all, 142 patients (46%) were diagnosed with HF. NT-proBNP concentrations in nondeglycosylated samples distinguished HF patients from patients with non-HF related dyspnea [median 3588 (quartiles 1-3 1578-8404) vs 360 (126-1139) ng/L, P < 0.001], but concentrations were markedly higher in samples pretreated with deglycosylation enzymes (total NT-proBNP) [7497 (3374-14 915) vs 798 (332-2296) ng/L, P < 0.001]. The AUC to separate HF patients from patients with non-HF related dyspnea was 0.871 (95% CI 0.829-0.907) for total NT-proBNP compared with 0.852 (0.807-0.890) for NT-proBNP measurements in standard EDTA plasma. During a median follow-up of 816 days, 112 patients (36%) died. Both NT-proBNP and total NT-proBNP concentrations were associated with mortality in separate multivariate models, but only total NT-proBNP concentrations provided added value to the basic risk model of our dataset as assessed by the net reclassification index: 0.24 (95% CI 0.003-0.384). There was a graded increase in risk across total NT-proBNP quartiles, in contrast with the results for NT-proBNP measurements. CONCLUSIONS: NT-proBNP concentrations were higher, and diagnostic and prognostic accuracy was improved, by pretreating tubes with deglycosylation enzymes.

Neutral endopeptidase inhibition and the natriuretic peptide system: an evolving strategy in cardiovascular therapeutics.

Hypertension and heart failure (HF) are common diseases that, despite advances in medical therapy, continue to be associated with high morbidity and mortality. Therefore, innovative therapeutic strategies are needed. Inhibition of the neutral endopeptidase (NEPinh) had been investigated as a potential novel therapeutic approach because of its ability to increase the plasma concentrations of the natriuretic peptides (NPs). Indeed, the NPs have potent natriuretic and vasodilator properties, inhibit the activity of the renin-angiotensin-aldosterone system, lower sympathetic drive, and have antiproliferative and antihypertrophic effects. Such potentially beneficial effects can be theoretically achieved by the use of NEPinh. However, studies have shown that NEPinh alone does not result in clinically meaningful blood pressure-lowering actions. More recently, NEPinh has been used in combination with other cardiovascular agents, such as angiotensin-converting enzyme inhibitors, and antagonists of the angiotensin receptor. Another future possible combination would be the use of NEPinh with NPs or their newly developed chimeric peptides. This review summarizes the current knowledge of the use and effects of NEPinh alone or in combination with other therapeutic agents for the treatment of human cardiovascular disease such as HF and hypertension.

Caloric Restriction Rejuvenates Skeletal Muscle Growth in Heart Failure With Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is a major clinical problem, with limited treatments. HFpEF is characterized by a distinct, but poorly understood, skeletal muscle pathology, which could offer an alternative therapeutic target. In a rat model, we identified impaired myonuclear accretion as a mechanism for low myofiber growth in HFpEF following resistance exercise. Acute caloric restriction rescued skeletal muscle pathology in HFpEF, whereas cardiac therapies had no effect. Mechanisms regulating myonuclear accretion were dysregulated in patients with HFpEF. Overall, these findings may have widespread implications in HFpEF, indicating combined dietary with exercise interventions as a beneficial approach to overcome skeletal muscle pathology.

Novel enhancers of guanylyl cyclase-A activity acting via allosteric modulation.

BACKGROUND AND PURPOSE: Guanylyl cyclase-A (GC-A), activated by endogenous atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), plays an important role in the regulation of cardiovascular and renal homeostasis and is an attractive drug target. Even though small molecule modulators allow oral administration and longer half-life, drug targeting of GC-A has so far been limited to peptides. Thus, in this study we aimed to develop small molecular activators of GC-A. EXPERIMENTAL APPROACH: Hits were identified through high-throughput screening and optimized by in silico design. Cyclic GMP was measured in QBIHEK293A cells expressing GC-A, GC-B or chimerae of the two receptors using AlphaScreen technology. Binding assays were performed in membrane preparations or whole cells using 125 I-ANP. Vasorelaxation was measured in aortic rings isolated from Wistar rats. KEY RESULTS: We have identified small molecular allosteric enhancers of GC-A, which enhanced ANP or BNP effects in cellular systems and ANP-induced vasorelaxation in rat aortic rings. The mechanism of action appears novel and not mediated through previously described allosteric binding sites. In addition, the selectivity and activity depend on a single amino acid residue that differs between the two similar receptors GC-A and GC-B. CONCLUSION AND IMPLICATIONS: We describe a novel allosteric binding site on GC-A, which can be targeted by small molecules to enhance ANP and BNP effects. These compounds will be valuable tools in further development and proof-of-concept of GC-A enhancement for the potential use in cardiovascular therapy.

Long-term cardiac pro-B-type natriuretic peptide gene delivery prevents the development of hypertensive heart disease in spontaneously hypertensive rats.

BACKGROUND: Diastolic dysfunction associated with high blood pressure (BP) leads to cardiac remodeling and fibrosis and progression to congestive heart failure. B-type natriuretic peptide (BNP) has BP-lowering, antifibrotic, and antihypertrophic properties, which makes BNP an attractive agent for attenuating the adverse cardiac remodeling associated with hypertension. In the current study, we tested the effects of sustained cardiac proBNP gene delivery on BP, cardiac function, and remodeling in spontaneously hypertensive rats (SHR). METHODS AND RESULTS: We used the myocardium-tropic adeno-associated virus serotype 9 (AAV9) vector to achieve continuously enhanced cardiac rat proBNP expression. In SHR, a single systemic administration of AAV9 vector allowed long-term cardiac BNP overexpression, resulting in reductions in systolic and diastolic BP for 9 months after injection. Left ventricular (LV) thickness, LV end-systolic dimensions, and LV mass were reduced, whereas ejection fraction was significantly increased, in BNP-treated compared with untreated SHR. Circumferential systolic strain and strain rate of the early phase of diastole were improved in BNP-treated compared with untreated SHR. Noncardiac overexpression of BNP via AAV2 vector was not associated with changes in BP and plasma BNP in SHR. Furthermore, normal Wistar rats injected with AAV9 proBNP vector showed significantly reduced heart weights 4 weeks after injection without BP reduction. CONCLUSIONS: AAV9 vector facilitates sustained cardiac proBNP overexpression and improves LV function in hypertensive heart disease. Long-term proBNP delivery improved both systolic and diastolic function. The effects on cardiac structure and function occurred independently of BP-lowering effects in normal Wistar rats.

Experimental mild renal insufficiency mediates early cardiac apoptosis, fibrosis, and diastolic dysfunction: a kidney-heart connection.

Impaired renal function with loss of nephron number in chronic renal disease (CKD) is associated with increased cardiovascular morbidity and mortality. However, the structural and functional cardiac response to early and mild reduction in renal mass is poorly defined. We hypothesized that mild renal impairment produced by unilateral nephrectomy (UNX) would result in early cardiac fibrosis and impaired diastolic function, which would progress to a more global left ventricular (LV) dysfunction. Cardiorenal function and structure were assessed in rats at 4 and 16 wk following UNX or sham operation (Sham); (n = 10 per group). At 4 wk, blood pressure (BP), aldosterone, glomerular filtration rate (GFR), proteinuria, and plasma B-type natriuretic peptide (BNP) were not altered by UNX, representing a model of mild early CKD. However, UNX was associated with significantly greater LV myocardial fibrosis compared with Sham. Importantly, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining revealed increased apoptosis in the LV myocardium. Further, diastolic dysfunction, assessed by strain echocardiography, but with preserved LVEF, was observed. Changes in genes related to the TGF-ß and apoptosis pathways in the LV myocardium were also observed. At 16 wk post-UNX, we observed persistent LV fibrosis and impairment in LV diastolic function. In addition, LV mass significantly increased, as did LVEDd, while there was a reduction in LVEF. Aldosterone, BNP, and proteinuria were increased, while GFR was decreased. The myocardial, structural, and functional alterations were associated with persistent changes in the TGF-ß pathway and even more widespread changes in the LV apoptotic pathway. These studies demonstrate that mild renal insufficiency in the rat results in early cardiac fibrosis and impaired diastolic function, which progresses to more global LV remodeling and dysfunction. Thus, these studies importantly advance the concept of a kidney-heart connection in the control of myocardial structure and function.

Diagnostic performance of microRNAs in the detection of heart failure with reduced or preserved ejection fraction: a systematic review and meta-analysis.

AIM: Chronic heart failure (CHF) can be classified as heart failure with preserved ejection fraction (HFpEF) or with reduced ejection fraction (HFrEF). Currently, there is an unmet need for a minimally invasive diagnostic tool for different forms of CHF. We aimed to investigate the diagnostic potential of circulating microRNAs (miRNAs) for the detection of different CHF forms via a systematic review and meta-analysis approach. METHODS AND RESULTS: Comprehensive search on Medline, Web of Science, Scopus, and EMBASE identified 45 relevant studies which were used for qualitative assessment. Out of these, 29 studies were used for qualitative and quantitative assessment and allowed to identify a miRNA panel able to detect HFrEF and HFpEF with areas under the curve (AUC) of 0.86 and 0.79, respectively. A panel of eight miRNAs (hsa-miR-18b-3p, hsa-miR-21-5p, hsa-miR-22-3p, hsa-miR-92b-3p, hsa-miR-129-5p, hsa-miR-320a-5p, hsa-miR-423-5p, and hsa-miR-675-5p) detected HFrEF cases with a sensitivity of 0.85, specificity of 0.88 and AUC of 0.91. A panel of seven miRNAs (hsa-miR-19b-3p, hsa-miR-30c-5p, hsa-miR-206, hsa-miR-221-3p, hsa-miR-328-5p, hsa-miR-375-3p, and hsa-miR-424-5p) identified HFpEF cases with a sensitivity of 0.82 and a specificity of 0.61. CONCLUSIONS: Although conventional biomarkers (N-terminal pro-B-type natriuretic peptide and B-type natriuretic peptide) presented a better performance in detecting CHF patients, the results presented here pointed towards specific miRNA panels with potential additive values to circulating natriuretic peptides in the diagnosis of different classes of CHF. Equally important, miRNAs alone showed a reasonable capacity for 'ruling out' patients with HFrEF or HFpEF. Additional studies with large populations are required to confirm the diagnostic potential of miRNAs for sub-classes of CHF.

Early cardiac-chamber-specific fingerprints in heart failure with preserved ejection fraction detected by FTIR and Raman spectroscopic techniques.

The pathophysiology of heart failure with preserved ejection fraction (HFpEF) is a matter of investigation and its diagnosis remains challenging. Although the mechanisms that are responsible for the development of HFpEF are not fully understood, it is well known that nearly 80% of patients with HFpEF have concomitant hypertension. We investigated whether early biochemical alterations were detectable during HFpEF progression in salt-induced hypertensive rats, using Fourier-transformed infrared (FTIR) and Raman spectroscopic techniques as a new diagnostic approach. Greater protein content and, specifically, greater collagen deposition were observed in the left atrium and right ventricle of hypertensive rats, together with altered metabolism of myocytes. Additionally, Raman spectra indicated a conformational change, or different degree of phosphorylation/methylation, in tyrosine-rich proteins. A correlation was found between tyrosine content and cardiac fibrosis of both right and left ventricles. Microcalcifications were detected in the left and right atria of control animals, with a progressive augmentation from six to 22 weeks. A further increase occurred in the left ventricle and right atrium of 22-week salt-fed animals, and a positive correlation was shown between the mineral deposits and the cardiac size of the left ventricle. Overall, FTIR and Raman techniques proved to be sensitive to early biochemical changes in HFpEF and preceded clinical humoral and imaging markers.

Urinary C-type natriuretic peptide excretion: a potential novel biomarker for renal fibrosis during aging.

Renal aging is characterized by structural changes in the kidney including fibrosis, which contributes to the increased risk of kidney and cardiac failure in the elderly. Studies involving healthy kidney donors demonstrated subclinical age-related nephropathy on renal biopsy that was not detected by standard diagnostic tests. Thus there is a high-priority need for novel noninvasive biomarkers to detect the presence of preclinical age-associated renal structural and functional changes. C-type natriuretic peptide (CNP) possesses renoprotective properties and is present in the kidney; however, its modulation during aging remains undefined. We assessed circulating and urinary CNP in a Fischer rat model of experimental aging and also determined renal structural and functional adaptations to the aging process. Histological and electron microscopic analysis demonstrated significant renal fibrosis, glomerular basement membrane thickening, and mesangial matrix expansion with aging. While plasma CNP levels progressively declined with aging, urinary CNP excretion increased, along with the ratio of urinary to plasma CNP, which preceded significant elevations in proteinuria and blood pressure. Also, CNP immunoreactivity was increased in the distal and proximal tubules in both the aging rat and aging human kidneys. Our findings provide evidence that urinary CNP and its ratio to plasma CNP may represent a novel biomarker for early age-mediated renal structural alterations, particularly fibrosis. Thus urinary CNP could potentially aid in identifying subjects with preclinical structural changes before the onset of symptoms and disease, allowing for the initiation of strategies designed to prevent the progression of chronic kidney disease particularly in the aging population.

Secretion of glycosylated pro-B-type natriuretic peptide from normal cardiomyocytes.

BACKGROUND: B-type natriuretic peptide (BNP), a key cardiac hormone in cardiorenal homeostasis, is produced as a 108 amino acid prohormone, proBNP1-108, which is converted to a biologically active peptide BNP1-32 and an inactive N-terminal (NT)-proBNP1-76. The widely accepted model is that the normal heart releases a proteolytically processed BNP1-32 and NT-proBNP, whereas the diseased heart secretes high amounts of unprocessed/glycosylated proBNP1-108 or inappropriately processed BNPs. In contrast, circulating proBNP1-108 has recently been identified in healthy individuals, indicating that the normal heart also secretes unprocessed proBNP1-108. However, the mechanism of proBNP1-108 secretion from the normal heart remains elusive. Our goal was to determine the molecular mechanisms underlying proBNP1-108 intracellular trafficking and secretion from the normal heart. METHODS: We expressed preproBNP in cardiomyocytes, and determined the subcellular localization and dominant intracellular and extracellular forms of BNP. RESULTS: Intracellular immunoreactive BNPs were first accumulated in the Golgi apparatus, and then distributed throughout the cytoplasm as secretory vesicles. The predominant intracellular form of BNP was nonglycosylated proBNP1-108, rather than BNP1-32. Glycosylated proBNP1-108, but not nonglycosylated proBNP1-108, was detected as the major extracellular form in the culture supernatants of preproBNP-expressing cell lines and primary human cardiomyocytes. Ablation of O-glycosylation of proBNP1-108 at T71 residue, near the convertase recognition site, reduced the extracellular proBNP1-108 and increased extracellular BNP1-32. CONCLUSIONS: Intracellular proBNP trafficking occurs through a conventional Golgi-endoplasmic reticulum pathway. Glycosylation of proBNP1-108 controls the stability and processing of extracellular proBNP1-108. Our data establish a new BNP secretion model in which the normal cardiac cells secrete glycosylated proBNP1-108.

Atrial Natriuretic Peptide31-67: A Novel Therapeutic Factor for Cardiovascular Diseases.

The characterization of the cardiac hormone atrial natriuretic peptide (ANP9 9 - 1 26), synthesized and secreted predominantly by atrial myocytes under stimulation by mechanical stretch, has established the heart as an endocrine organ with potent natriuretic, diuretic, and vasodilating actions. Three additional distinct polypeptides resulting from proteolytic cleavage of proANP have been identified in the circulation in humans. The mid-sequence proANP fragment 31-67 (also known as proANP3 1 - 6 7) has unique potent and prolonged diuretic and natriuretic properties. In this review, we report the main effects of this circulating hormone in different tissues and organs, and its mechanisms of actions. We further highlight recent evidence on the cardiorenal protective actions of chronic supplementation of synthetic proANP3 1 - 6 7 in preclinical models of cardiorenal disease. Finally, we evaluate the use of proANP3 1 - 6 7 as a new therapeutic strategy to repair end-organ damage secondary to hypertension, diabetes mellitus, renal diseases, obesity, heart failure, and other morbidities that can lead to impaired cardiac function and structure.

Distorted assessment of left atrial size by echocardiography in patients with increased aortic root diameter.

BACKGROUND: Left atrial (LA) size is frequently assessed by posterior-anterior linear measurement of LA (LAD P-A) in the parasternal long axis to expedite examination. Aging, changes in body surface area, and several cardiovascular pathologies can affect aortic root (AoR) size, thereby affecting LA anatomical shape. We hypothesized that AoR dilatation influences LAD P-A and consequently correct assessment of LA size. RESULTS: We tested our hypothesis in a study of 70 patients with AoR diameter ranging from 2.7 to 4.8 cm. LA size assessed in parasternal long axis view as LAD P-A was compared to that with LA width and length acquired in the apical two and four chamber view. Simpson's method of discs was used as standard measurement to assess LA volume. We observed that LAD P-A in the parasternal long axis decreases when AoR diameter increases. Thus, the increase in LA size assessed in parasternal long axis did not correlate with the increase of LA volume. Further analysis revealed that a significant positive correlation was observed when LAV was plotted as a function of LAD P-A only for those with a normal size AoR. In contrast, LA volume increase correlated with LA diameters assessed in the apical two and four chamber view regardless of AoR size. CONCLUSIONS: Our study documents that increases in AoR impact on the linear measurement of LA, resulting in an underestimated LAD P-A. LA size ought to be calculated from the apical two and four chambers view parameters, especially in patients with AoR dilatation.

Sacubitril/valsartan ameliorates cardiac hypertrophy and preserves diastolic function in cardiac pressure overload.

AIMS: Sacubitril/valsartan (sac/val) has shown superior effect compared with blockade of the renin-angiotensin-aldosterone system in heart failure with reduced ejection fraction. We aimed to investigate effects of sac/val compared with valsartan in a pressure overload model of heart failure with preserved ejection fraction (HFpEF). METHODS AND RESULTS: Sprague-Dawley rats underwent aortic banding or sham (n = 16) surgery and were randomized to sac/val (n = 28), valsartan (n = 29), or vehicle (n = 26) treatment for 8 weeks. Sac/val reduced left ventricular weight by 11% compared with vehicle (P = 0.01) and 9% compared with valsartan alone (P = 0.04). Only valsartan reduced blood pressure compared with sham (P = 0.02). Longitudinal early diastolic strain rate was preserved in sac/val compared with sham, while it was reduced by 23% in vehicle (P = 0.03) and 24% in valsartan (P = 0.02). Diastolic dysfunction, measured by E/e'SR, increased by 68% in vehicle (P < 0.01) and 80% in valsartan alone (P < 0.001), while sac/val showed no increase. Neither sac/val nor valsartan prevented interstitial fibrosis. Although ejection fraction was preserved, we observed mild systolic dysfunction, with vehicle showing a 28% decrease in longitudinal strain (P < 0.01). Neither sac/val nor valsartan treatment improved this dysfunction. CONCLUSIONS: In a model of HFpEF induced by cardiac pressure overload, sac/val reduced hypertrophy compared with valsartan alone and ameliorated diastolic dysfunction. These effects were independent of blood pressure. Early systolic dysfunction was not affected, supporting the notion that sac/val has the largest potential in conditions characterized by reduced ejection fraction. Observed anti-hypertrophic effects in preserved ejection fraction implicate potential benefit of sac/val in the clinical setting of hypertrophic remodelling and impaired diastolic function.

Etiology-Dependent Impairment of Diastolic Cardiomyocyte Calcium Homeostasis in Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Whereas heart failure with reduced ejection fraction (HFrEF) is associated with ventricular dilation and markedly reduced systolic function, heart failure with preserved ejection fraction (HFpEF) patients exhibit concentric hypertrophy and diastolic dysfunction. Impaired cardiomyocyte Ca2+ homeostasis in HFrEF has been linked to disruption of membrane invaginations called t-tubules, but it is unknown if such changes occur in HFpEF. OBJECTIVES: This study examined whether distinct cardiomyocyte phenotypes underlie the heart failure entities of HFrEF and HFpEF. METHODS: T-tubule structure was investigated in left ventricular biopsies obtained from HFrEF and HFpEF patients, whereas cardiomyocyte Ca2+ homeostasis was studied in rat models of these conditions. RESULTS: HFpEF patients exhibited increased t-tubule density in comparison with control subjects. Super-resolution imaging revealed that higher t-tubule density resulted from both tubule dilation and proliferation. In contrast, t-tubule density was reduced in patients with HFrEF. Augmented collagen deposition within t-tubules was observed in HFrEF but not HFpEF hearts. A causative link between mechanical stress and t-tubule disruption was supported by markedly elevated ventricular wall stress in HFrEF patients. In HFrEF rats, t-tubule loss was linked to impaired systolic Ca2+ homeostasis, although diastolic Ca2+ removal was also reduced. In contrast, Ca2+ transient magnitude and release kinetics were largely maintained in HFpEF rats. However, diastolic Ca2+ impairments, including reduced sarco/endoplasmic reticulum Ca2+-ATPase activity, were specifically observed in diabetic HFpEF but not in ischemic or hypertensive models. CONCLUSIONS: Although t-tubule disruption and impaired cardiomyocyte Ca2+ release are hallmarks of HFrEF, such changes are not prominent in HFpEF. Impaired diastolic Ca2+ homeostasis occurs in both conditions, but in HFpEF, this mechanism for diastolic dysfunction is etiology-dependent.