scholarly journals Metformin improves diastolic function in an HFpEF-like mouse model by increasing titin compliance

2018 ◽  
Vol 151 (1) ◽  
pp. 42-52 ◽  
Author(s):  
Rebecca E. Slater ◽  
Joshua G. Strom ◽  
Mei Methawasin ◽  
Martin Liss ◽  
Michael Gotthardt ◽  
...  
Keyword(s):  
Ejection Fraction ◽  
Mouse Model ◽  
Diastolic Function ◽  
Left Ventricular ◽  
Muscle Stiffness ◽  
Exercise Intolerance ◽  
Diabetic Patients ◽  
Preserved Ejection Fraction ◽  
Passive Stiffness ◽  
Diastolic Stiffness

Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome characterized by a preserved ejection fraction but increased diastolic stiffness and abnormalities of filling. Although the prevalence of HFpEF is high and continues to rise, no effective therapies exist; however, the diabetic drug metformin has been associated with improved diastolic function in diabetic patients. Here we determine the therapeutic potential of metformin for improving diastolic function in a mouse model with HFpEF-like symptoms. We combine transverse aortic constriction (TAC) surgery with deoxycorticosterone acetate (DOCA) supplementation to obtain a mouse model with increased diastolic stiffness and exercise intolerance. Echocardiography and pressure–volume analysis reveal that providing metformin to TAC/DOCA mice improves diastolic function in the left ventricular (LV) chamber. Muscle mechanics show that metformin lowers passive stiffness of the LV wall muscle. Concomitant with this improvement in diastolic function, metformin-treated TAC/DOCA mice also demonstrate preserved exercise capacity. No metformin effects are seen in sham operated mice. Extraction experiments on skinned ventricular muscle strips show that the metformin-induced reduction of passive stiffness in TAC/DOCA mice is due to an increase in titin compliance. Using phospho-site-specific antibodies, we assay the phosphorylation of titin’s PEVK and N2B spring elements. Metformin-treated mice have unaltered PEVK phosphorylation but increased phosphorylation of PKA sites in the N2B element, a change which has previously been shown to lower titin’s stiffness. Consistent with this result, experiments with a mouse model deficient in the N2B element reveal that the beneficial effect of metformin on LV chamber and muscle stiffness requires the presence of the N2B element. We conclude that metformin offers therapeutic benefit during HFpEF by lowering titin-based passive stiffness.

scholarly journals Mechanistic dissection of global proteomic changes in rats with heart failure and preserved ejection fraction

2021 ◽  
Author(s):  
Daniel Soetkamp ◽  
Aleksandra Binek ◽  
Romain Gallet ◽  
Geoffrey de Couto ◽  
Peter Kilfoil ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Diastolic Dysfunction ◽  
Diastolic Function ◽  
Left Ventricular ◽  
Exercise Intolerance ◽  
Therapeutic Effects ◽  
Preserved Ejection Fraction ◽  
Salt Diet ◽  
Upstream Regulators

Introduction: Heart failure with preserved ejection fraction (HFpEF) is characterized by diastolic dysfunction, pulmonary congestion and exercise intolerance. Previous preclinical studies show that treatment with cardiosphere-derived cells (CDCs) improves diastolic function, attenuates arrhythmias and prolongs survival in a rat HFpEF model. Here we characterize the myocardial proteome and diastolic function in HFpEF, with and without CDC therapy. As an initial strategy for identifying pathways worthy of further mechanistic dissection, we correlated CDC-responsive proteomic changes with functional improvements. Methods and Results: Dahl salt-sensitive rats fed high-salt diet, with verified diastolic dysfunction, were randomly assigned to intracoronary CDCs or placebo. Dahl rats fed a low salt diet served as controls. Phenotyping was by echocardiography (E/A ratio) and invasive hemodynamic monitoring (time constant of relaxation Tau, and left ventricular end-diastolic pressure [LVEDP]). CDC treatment improved diastolic function as indicated by a normalized E/A ratio, a 33.3% reduction in Tau, and a 47% reduction of LVEDP. Mass spectrometry of left ventricular tissues (n=6/group) revealed changes in transcription and translation pathways in this rat HFpEF model and was also recapitulated in human HFpEF. These pathways were enhanced following CDC treatment in the animal model (205 proteins and 32 phosphorylated residues accounting for 37% and 19% of all changes, respectively). Among all CDC-sensitive pathways, 65% can be linked to at least 1 of 7 upstream regulators, among which several are of potential relevance for regulating protein expression. To probe newly-synthesized proteins AHA labeling was carried out in isolated rat cardiomyocytes obtained from HFpEF groups, with and without CDC therapy. Five of the initial upstream regulators (HNF4A, MTOR, MYC, TGFβ1, and TP53) were linked to proteins expressed exclusively (or increased) with CDC treatment. All 32 phosphorylated residues of proteins involved in transcription/translation altered specifically by CDC treatment had predicted kinases (Protein kinase C (PKC) being the most dominant) and known to be regulated by MYC, TGFβ1 and/or TP53. Western blot analysis of those 5 upstream regulators showed that TGFβ1, TP53, and Myc were significantly decreased in LV from CDC treated animals, whereas MTOR and HNF4A showed a significant increase compared to HFpEF alone. The cellular quantities of several upstream regulator correlated with indices of diastolic function (E/A ratio, Tau and/or LVEDP). Since CDCs act via the secretion of exosomes laden with signaling cargo, it is relevant that all 7 upstream regulators could, in principle, be regulated by proteins or miRNA that are present in CDC-derived exosomes. Conclusion: We identified key cellular regulators of transcription and translation that underlie the therapeutic effects of CDCs in HFpEF, whose levels correlate quantitatively with measures of diastolic function. Among the multifarious proteomic changes associated with rat model of HFpEF which were also observed in human HFpEF samples, we propose that these regulators, and downstream effector kinases, be prioritized for further dedicated mechanistic dissection.

scholarly journals Linking diastolic function to cardiac exercise performance in heart failure with preserved ejection fraction: a virtual patient study

2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
T Van Loon ◽  
C Knackstedt ◽  
R Cornelussen ◽  
KD Reesink ◽  
HP Brunner-La-Rocca ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Diastolic Function ◽  
Exercise Performance ◽  
Left Atrial ◽  
Relaxation Function ◽  
Left Ventricular ◽  
Preserved Ejection Fraction ◽  
Passive Stiffness ◽  
Wide Range

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NWO-ZonMw Background The relative impact of left ventricular (LV) diastolic dysfunction (LVDD) and impaired left atrial (LA) function on cardiac exercise performance (CEP) in heart failure with preserved ejection fraction (HFpEF) remains largely unknown Purpose To elucidate the relative effects of LVDD and impaired LA function on hemodynamics at rest and on cardiac performance during exercise by performing virtual HFpEF patient simulations. Methods Using a well-validated cardiovascular system model (CircAdapt), impaired LV relaxation was simulated by increasing the rate of myocardial relaxation (tau) from 35 to 65 ms. To study the effect of moderate and sever LV myocardial stiffness increase, LV end-diastolic elastance was increased from 0.15 mmHg/ml to 0.60 mmHg/ml and 2.00 mmHg/ml, respectively. In each simulation, LV diastolic function at rest (cardiac output (CO) and heart rate (HR) of 5.1 l/min and 70 bpm, respectively) was assessed using LV ejection fraction (LVEF), mitral E/A ratio, maximum LA volume (LAV), and mean left atrial (LA) pressure (mLAP). To investigate the relative effect of these cardiac abnormalities on exercise capacity, CO and HR were gradually increased using a fixed CO-HR relationship until mLAP exceeded a threshold pressure of 35 mmHg, which was assumed to be a physiological limit of exercise intensity. Results Simulations showed that regardless of the modelled LV and LA function, LVEF was preserved (>50%). Impaired LV relaxation function was associated with decreased E/A-ratio and a small increase in mLAP at rest, regardless of LA function. Increased LV passive stiffness resulted in increased E/A-ratio, LA dilation and markedly elevated mLAP at rest, regardless of LA function (Figure: top-left). Impaired LA function resulted in reduced A-peak velocity, and increased E/A–ratio, LAV and mLAP at rest regardless of LV function (Figure: top-right) Exercise simulations showed that increased LV passive stiffness exerts a stronger exercise-limiting effect than impaired LV relaxation function, in particular when LA function is impaired (Figure: bottom). Conclusions Through simple and well-controlled variations in LV and LA function, we were able to simulate virtual HFpEF patients with a wide range of LVDD severities at rest, preserved LVEF, and reduced cardiac exercise performance. In general, our simulations suggest that increased LV passive stiffness, rather than impaired LV relaxation function, reduces exercise tolerance, especially in the presence of LA dysfunction. Abstract Figure. Simulating rest & exercise hemodynamics

Abstract 215: The Role of Titin in Cardiac Function: Studies in Two Genetically Engineered Mouse Models With Disparate Titin’s Size

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Mei Methawasin ◽  
Kirk R Hutchinson ◽  
John E Smith ◽  
Henk L Granzier
Keyword(s):  
Mouse Model ◽  
Diastolic Dysfunction ◽  
Diastolic Function ◽  
Exercise Capacity ◽  
Mouse Models ◽  
Wheel Running ◽  
Left Ventricular ◽  
Genetically Engineered ◽  
Passive Stiffness ◽  
Genetically Engineered Mouse Models

Titin, a myofilament that acts as a molecular spring in the sarcomere, is considered the main contributor to passive stiffness of cardiomyocytes and is responsible for cardiac diastolic function. Increased titin stiffness is related to diastolic dysfunction and HFpEF (Heart Failure with preserved Ejection Fraction). Alteration in size of titin’s spring region leads to changes in cardiomyocyte and left ventricular (LV) chamber stiffness. We tested the effect of alteration in titin’s size in two genetically engineered mouse models. We investigated the effect of shortening titin’s spring region in a mouse model in which I-band/A-band region of titin’s spring has been deleted (TtnΔIAjxn ), in comparison to the effect of lengthening titin’s spring region in a mouse model deficient in titin splicing factor (Rbm20ΔRRM). Integrative approaches were used from single cardiomyocyte mechanics to pressure-volume analysis and exercise study. Study of skinned LV cardiomyocytes revealed that cellular passive stiffness was inversely related to the size of titin. Cellular passive stiffness was increased in TtnΔIAjxn homozygous (-/-) (~ 110 % higher than wildtype (WT)) and was reduced in a graded manner in Rbm20ΔRRM heterozygous (+/-) and -/- cardiomyocytes (~61% and ~87% less than WT). This effect was carried through at the LV chamber level which could be demonstrated in pressure volume (PV) analysis as an increased end-diastolic pressure-volume relationship (EDPVR) in TtnΔIAjxn -/- (~110% higher than WT’s hearts) and reduced EDPVR in Rbm20ΔRRM +/- and -/- (~57% and ~48% less than WT’s hearts). Free-wheel running studies revealed a running deficiency in TtnΔIAjxn -/- mice but an increase in exercise capacity in Rbm20ΔRRM +/– mice. Conclusions: Functional studies from the cellular to in-vivo LV chamber levels showed that mice with shortening of titin’s spring region had increased LV stiffness, diastolic dysfunction and reduced exercise capacity, while mice with lengthening titin’s spring region had compliant LV and increased exercise capacity. Thus, our work supports titin’s important roles in LV diastolic function and suggests that modification of the size of titin’s spring region could be a potential therapeutic strategy for HFpEF.

scholarly journals Application of the current HFA-ESC consensus guidelines on diagnosis of heart failure with preserved ejection fraction to a population referred for echocardiography

2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
K Liang ◽  
R Hearse-Morgan ◽  
S Fairbairn ◽  
Y Ismail ◽  
AK Nightingale
Keyword(s):  
Heart Failure ◽  
Atrial Fibrillation ◽  
Ejection Fraction ◽  
Diastolic Function ◽  
Global Longitudinal Strain ◽  
Diagnostic Algorithm ◽  
Left Ventricular ◽  
Lv Function ◽  
Preserved Ejection Fraction ◽  
Consensus Guidelines

Abstract Funding Acknowledgements Type of funding sources: None. BACKGROUND The recent Heart Failure Association (HFA) of the European Society of Cardiology (ESC) consensus guidelines on diagnosis of heart failure with preserved ejection fraction (HFpEF) have developed a simple diagnostic algorithm for clinical use. PURPOSE To assess whether echocardiogram (echo) parameters needed to assess diastolic function are routinely collected in patients referred for assessment of heart failure symptoms. METHODS Retrospective analysis of echo referrals in January 2020 were assessed for parameters of diastolic function as per step 2 of the HF-PEFF diagnostic algorithm.  Echo images and clinical reports were reviewed. Electronic records were utilised to obtain clinical history, blood results (NT-proBNP) and demographic data. RESULTS 1330 patients underwent an echo in our department during January 2020. 83 patients were referred with symptoms of heart failure without prior history of cardiac disease; 20 patients found to have impaired left ventricular (LV) function were excluded from analysis. Of the 63 patients with possible HFpEF, HF-PEFF score was low in 18, intermediate in 33 and high in 12. Median age was 68 years (range 32 to 97 years); 25% had a BMI >30. There was a high prevalence of hypertension (52%), diabetes (19%) and atrial fibrillation (40%) (cf. Table 1). Body surface area (BSA) was documented in 65% of echo reports. Most echo parameters were recorded with the exception of global longitudinal strain (GLS) and indexed LV mass (cf. image 1). NT-proBNP was recorded in only 20 patients (31.7%). 12 patients with an intermediate HF-PEFF score could have been re-categorised to a high score depending on GLS and NT-proBNP (which were not recorded). CONCLUSION More than three quarters of echoes acquired in our department obtained the relevant parameters to assess diastolic function. The addition of BSA, and inclusion of NT-proBNP, and GLS would have been additive to a third of ‘intermediate’ patients to determine definite HFpEF. Our study demonstrates that the current HFA-ESC diagnostic algorithm and HF-PEFF scoring system are easy to use, highly relevant and applicable to current clinical practice. Age >70 years 29 (46.0%) Obesity (BMI >30) 16 (25.4%) Diabetes 12 (19%) Hypertension 33 (52.4%) Atrial Fibrillation 25 (39.7%) ECG abnormalities 18 (28.5%) Table 1. Prevalence of Clinical Risk Factors Abstract Figure. Image 1. HFPEFF score & echo parameters

scholarly journals Features of heart failure with preserved ejection fraction (HFpEF) in diabetic patients with resistant hypertension

2021 ◽  
Vol 24 (4) ◽  
pp. 304-314
Author(s):  
M. A. Manukyan ◽  
A. Y. Falkovskaya ◽  
V. F. Mordovin ◽  
T. R. Ryabova ◽  
I. V. Zyubanova ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Heart Failure ◽  
Blood Pressure ◽  
Blood Flow ◽  
Ejection Fraction ◽  
Diastolic Dysfunction ◽  
Diastolic Function ◽  
Resistant Hypertension ◽  
Diabetic Patients ◽  
Preserved Ejection Fraction

BACKGROUND: It is expected that a steady increase in the incidence of diabetes and resistant hypertension (RHTN), along with an increase in life expectancy, will lead to a noticeable increase in the proportion of patients with heart failure with preserved ejection fraction (HFpEF). At the same time, data on the frequency of HFpEF in a selective group of patients with RHTN in combination with diabetes are still lacking, and the pathophysiological and molecular mechanisms of its formation have not been yet studied sufficiently.AIM: To assess the features of the development HFpEF in diabetic and non-diabetic patients with RHTN, as well as to determine the factors associated with HFpEF.MATERIALS AND METHODS: In the study were included 36 patients with RHTN and type 2 diabetes mellitus (DM) (mean age 61.4 ± 6.4 years, 14 men) and 33 patients with RHTN without diabetes, matched by sex, age and level of systolic blood pressure (BP). All patients underwent baseline office and 24-hour BP measurement, echocardiography with assess diastolic function, lab tests (basal glycemia, HbA1c, creatinine, aldosterone, TNF-alpha, hsCRP, brain naturetic peptide, metalloproteinases of types 2, 9 (MMP-2, MMP-9) and tissue inhibitor of MMP type 1 (TIMP-1)). HFpEF was diagnosed according to the 2019 AHA/ESC guidelines.RESULTS: The frequency of HFpEF was significantly higher in patients with RHTN with DM than those without DM (89% and 70%, respectively, p=0.045). This difference was due to a higher frequency of such major functional criterion of HFpEF as E/e’≥15 (p=0.042), as well as a tendency towards a higher frequency of an increase in left atrial volumes (p=0.081) and an increase in BNP (p=0.110). Despite the comparable frequency of diastolic dysfunction in patients with and without diabetes (100% and 97%, respectively), disturbance of the transmitral blood flow in patients with DM were more pronounced than in those without diabetes. Deterioration of transmitral blood flow and pseudo-normalization of diastolic function in diabetic patients with RHTN have relationship not only with signs of carbohydrate metabolism disturbance, but also with level of pulse blood pressure, TNF-alfa, TIMP-1 and TIMP-1 / MMP-2 ratio, which, along with the incidence of atherosclerosis, were higher in patients with DM than in those without diabetes.CONCLUSIONS: Thus, HFpEF occurs in the majority of diabetic patients with RHTN. The frequency of HFpEF in patients with DN is significantly higher than in patients without it, which is associated with more pronounced impairments of diastolic function. The progressive development of diastolic dysfunction in patients with diabetes mellitus is associated not only with metabolic disorders, but also with increased activity of chronic subclinical inflammation, profibrotic state and high severity of vascular changes.

Abstract 14648: Interleukin-18 Blockade Prevents Diastolic Dysfunction in a Mouse Model of Heart Failure With Preserved Ejection Fraction

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Jessica A Regan ◽  
Adolofo G Mauro ◽  
Salvatore Carbone ◽  
Carlo Marchetti ◽  
Eleonora Mezzaroma ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Ejection Fraction ◽  
Mouse Model ◽  
Diastolic Dysfunction ◽  
Diastolic Function ◽  
Low Dose ◽  
Preserved Ejection Fraction ◽  
Interleukin 18 ◽  
Lv Diastolic Function

Background: Heart failure with preserved ejection fraction (HFpEF) is characterized by elevated left ventricular (LV) filling pressures due to impaired LV diastolic function. Low-dose infusion of angiotensin 2 (AT2) in the mouse induces a HFpEF phenotype without increasing blood pressure. AT2 infusion induces expression of Interleukin-18 (IL-18) in the heart. We therefore tested whether IL-18 mediated AT2-induced LV diastolic dysfunction in this model. Methods: We infused subcutaneously AT2 (0.2 mg/Kg/day) or a matching volume of vehicle via osmotic pumps surgically implanted in the interscapular space in adult wild-type (WT) male mice and IL-18 knock-out mice (IL-18KO). We also treated WT mice with daily intraperitoneal injections of recombinant murine IL-18 binding protein (IL-18bp, a naturally occurring IL-18 blocker) at 3 different doses (0.1, 0.3 and 1.0 mg/kg) or vehicle for 25 days starting on day 3. We performed a Doppler-echocardiography study before implantation and at 28 days to measure LV dimensions, mass, and systolic and diastolic function in all mice. LV catheterization was performed prior to sacrifice to measure LV end-diastolic pressure (LVEDP) using a Millar catheter. Results: AT2 induces a significant increase in isovolumetric relaxation time (IRT) and myocardial performance index (MPI) at Doppler echocardiography and elevation of LVEDP at catheterization, indicative of impaired LV diastolic function, in absence of any measurable effects on systolic blood pressure nor LV dimensions, mass, or systolic function. Mice with genetic deletion of IL-18 (IL-18 KO) or WT mice treated with IL-18bp had no significant increase in IRT, MPI or LVEDP with AT2 infusion. Conclusion: Genetic or pharmacologic IL-18 blockade prevent diastolic dysfunction in a mouse model of HFpEF induced by low dose AT2 infusion, suggesting a critical role of IL-18 in the pathophysiology of HFpEF.

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