Increase In End-diastolic Pressure Research Articles

Intact DNA repair in differentiated cardiomyocytes is essential for maintaining cardiac function in response to pressure overload in mice

Abstract Introduction DNA in every cell is continuously damaged and DNA repair mechanisms are essential for protection against DNA damage-induced aging-related diseases. For example, deficient repair of endogenously generated DNA damage in mice with cardiomyocyte-restricted inactivation of Xpg, is associated with progressive heart failure. Purpose Here we tested the hypothesis that unrepaired DNA damage in differentiated cardiomyocytes increases cardiac vulnerability in response to hemodynamic overload. Methods To increase the burden of spontaneous DNA damage, we generated mice with cardiomyocyte-restricted inactivation of DNA repair endonuclease XPG. At 8 weeks of age, αMHC-Xpgc/- and control (Ctrl) mice were subjected to pressure overload by transverse aortic constriction (TAC). Eight weeks after TAC, left ventricular (LV) function was assessed using echocardiography and hemodynamic measurements, followed by molecular and histological analyses. Results Cardiomyocyte-restricted inactivation of Xpg resulted in systolic as well as diastolic LV dysfunction (Table). TAC-induced LV hypertrophy is similar in both groups (Ctrl 38%; αMHC-Xpgc/- 34%). In Ctrl mice, LV hypertrophy was accompanied by minimal LV dilation and modest changes in systolic and diastolic LV function. Conversely, TAC in αMHC-Xpgc/- produced severe LV dysfunction and resulted in overt congestive heart failure, demonstrated by aggravation of LV dilation, and marked increases in LV end-diastolic pressure, left atrial weight and lung fluid weight, which was accompanied by further increases in the expression levels of the hypertrophic marker genes atrial natriuretic peptide and beta-myosin heavy chain (Table). Moreover, lectin staining revealed a decrease in capillary density and TUNEL staining revealed further elevated levels of myocardial apoptosis. In addition, a significant increase of myocardial collagen content was observed. Conclusion Cardiomyocyte-restricted loss of DNA repair protein XPG increases cardiac vulnerability to develop heart failure in response to pressure overload. These findings underscore the importance of genomic stability for maintenance of cardiac function, not only during basal conditions, but also in response to a pathological stimulus.

A less-invasive left atrial assist device concept for diastolic heart failure: First in vitro and in vivo assessment

ObjectiveA less-invasive left atrial assist device (LAADx) is a novel and implantable, extracardiac blood pump concept, intended for the treatment of diastolic heart failure, represented by heart failure with preserved ejection fraction. MethodsA mixed-flow pump was used as the working LAADx model. Its performance was evaluated at 3 speeds, using an in vitro pulsatile mock circulatory loop, with a pneumatic pump that can simulate diastolic heart failure conditions by adjusting the diastolic drive pressure. The LAADx model was implanted in 4 healthy calves. The pump's inflow and outflow cannulas were inserted into the left atrium (LA) and left ventricle (LV), respectively, without cardiopulmonary bypass. The LAADx was operated at 3 speeds, and diastolic heart failure-like conditions were induced by inflating a balloon, inserted into the LV. ResultsWith the in vitro study, diastolic heart failure-like conditions were successfully induced, exhibiting decreased cardiac output and aortic pressure as well as increased mean LA pressure both mitigated with the LAADx support. With regard to the in vivo study, simulated diastolic heart failure conditions showed a decrease in aortic pressure and an increase in LA pressure and LV end-diastolic pressure, which were again mitigated by the LAADx. Echocardiography showed good positioning of the outflow cannula and neither cardiac dysfunction nor mitral interference was observed. ConclusionsInitial in vitro and in vivo results confirmed that the LAADx model, a device concept driven by creating an extracardiac route from the LA to LV, has the potential to mitigate high LA pressure and improve LV filling of heart failure with preserved ejection fraction pathology.

Analysis of the significance of echocardiographic signs of right ventricular dysfunction for predicting the outcome of heart failure with reduced left ventricular ejection fraction

Objective: to determine the ultrasound signs of right heart dysfunction, which increase the prognostic value of the recommended parameters of left ventricular (LV) dysfunction in patients with heart failure with reduced ejection fraction (HFrEF).Materials and methods. The prospective study included 79 patients with HFrEF LV with clinical manifestations of chronic heart failure functional class III according to the New York Heart Association (HF NYHA Class III) in 52 patients (65.8%) and HF NYHA Class IV in 27 (34.1%). The primary end point was death during a follow-up period of up to 3 years while waiting for heart transplantation.Results. Overall mortality was 33 patients (41.7%), 17 (21.5%) during the 1st year of follow-up. Regression analysis revealed the following independent ultrasound predictors of poor prognosis: LV ejection fraction on 3D-echocardiography (3DE LVEF), p = 0.014; global longitudinal strain of the LV (GLS LV), p = 0.010, and of the interventricular septum basal segment (IVSLS BS), p = 0.012; mean longitudinal strain of the basal segment of the right ventricle free wall (FWLS BS RV), p = 0.003. Changes in the configuration and dilatation of the LV cavity, an increase in LV end-diastolic pressure, impaired contractility, and strain of the LV myocardium can affect the function of the right ventricle (RV) through the common interventricular septum (IVS). Dilatation of the RV due to an increase in the end diastolic area (RV EDA) of more than 30 cm2 (p = 0.012) and end systolic area (RV ESA) of more than 25 cm2 (p = 0.001), an increase in the volume of the right atrium (3DE AKI) of more than 100 ml (p = 0.036), and a decrease in the % inspiratory collapse of the inferior vena cava (% IVC) less than 30% (p = 0.005) demonstrated a prognostic significance in the observed patients. A decrease in the deformation properties of the pancreas due to the longitudinal component and impaired strain of the basal segment makes a greater contribution to RV dysfunction (FWLS BS, % < -15% (p < 0.001)).Conclusions. RV dysfunction in patients with HFrEF is an unfavorable prognostic factor, independently associated with existing LV dysfunction. The most significant ultrasound sign for surveillance prediction of patients with LV HFrEF and RV dysfunction are indicators of ventricular myocardial deformation. Remodeling of the right chambers and dysfunction of the RV is a trigger for the separation of the RV and pulmonary artery, which ultimately leads to adverse outcomes.

Intact DNA Repair in Differentiated Cardiomyocytes Is Essential for Maintaining Cardiac Function in Response to Pressure Overload in Mice

Introduction: DNA in every cell is continuously damaged and DNA repair mechanisms are essential for protection against DNA damage-induced aging-related diseases. For example, deficient repair of endogenously generated DNA damage in mice with cardiomyocyte-restricted inactivation of Xpg, is associated with progressive heart failure (de Boer et al. Aging Cell 2023). Here we tested the hypothesis that unrepaired DNA damage in differentiated cardiomyocytes increases cardiac vulnerability in response to hemodynamic overload. Methods: At 8 weeks of age, αMHC-Xpgc/- and control (Ctrl) mice were subjected to pressure overload by mild transverse aortic constriction (TAC). Eight weeks after TAC, left ventricular (LV) function was assessed using echocardiography and hemodynamic measurements, followed by histological and molecular analyses. Results: Cardiomyocyte-restricted inactivation of Xpg resulted in systolic as well as diastolic LV dysfunction. TAC-induced LV hypertrophy was similar in both groups (Ctrl 38%; αMHC-Xpgc/- 34%). In Ctrl mice, LV hypertrophy was accompanied by minimal LV dilation and only modest changes in systolic and diastolic LV function. Conversely, TAC in αMHC-Xpgc/- produced severe LV dilation and dysfunction and resulted in overt backward failure, demonstrated by marked increases in LV end-diastolic pressure, left atrial weight and lung fluid weight. These changes were accompanied by further increases in the expression levels of the hypertrophic marker genes atrial natriuretic peptide and beta-myosin heavy chain. Moreover, lectin staining revealed a decrease in capillary density and TUNEL staining revealed further elevated levels of myocardial apoptosis in αMHC-Xpgc/--TAC mice as compared to Ctrl-TAC mice. In addition, a significant increase of myocardial collagen content was observed in αMHC-Xpgc/--TAC but not in Ctrl-TAC mice. Conclusion: Cardiomyocyte-restricted loss of DNA repair protein Xpg increases cardiac vulnerability to develop heart failure in response to pressure-overload. These findings underscore the importance of genomic stability for maintenance of cardiac function, not only under basal conditions, but also during increased cardiac loading conditions. Supported by the Dutch Heart Foundation [Grants 2017B018-ARENA-PRIME; 2021B008-RECONNEXT]. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Thrombosis in the coronary microvasculature may be responsible for impaired cardiac relaxation and diastolic dysfunction

Abstract Introduction Heart Failure with Preserved Ejection Fraction (HFpEF) is proposed to be caused by endothelial dysfunction in cardiac small vessels. We previously identified Hhipl1,as a gene upregulated in the coronary vasculature of Leptin receptor deficient mice (Leprdb/db) a well-established mouse model of HFpEF. Importantly, Hhipl1 encodes for a decoy receptor of Desert Hedgehog (DHH) which is known to be critical for endothelial integrity. Objective Our objective is to investigate the functional consequences of impaired Hedgehog (HH) signaling in the adult heart in order to identify novel mechanisms underlying the development of diastolic dysfunction. Method To do so, Cdh5-Cre/ERT2, DhhFlox/Flox (DhhECKO) mice and their control littermates were administered with tamoxifen at 8 weeks of age to induce Dhh KO. Their cardiac function, exercise tolerance, and the phenotype of their coronary vasculature were assessed one month later. Results DhhECKO mice presented significantly reduced exercise tolerance, increased end diastolic pressure (EDP) and Tau, with no change in their ejection fraction consistent with diastolic dysfunction. At molecular and cellular level, impaired cardiac relaxation in DhhECKO mice was associated with a significantly decreased phospholamban phosphorylation on Thr17 and an alteration of sarcomeric shortening in ex-vivo. Besides, as expected, DhhECKO mice exhibited phenotypic changes in their coronary vasculature including a prominent pro-thrombotic phenotype (63±6,2 vs 25±5,2 thrombi/mm²; p<0,001) leading to an impaired capillary perfusion and local hypoxia. Notably, antiaggregant therapies (aspirin and clopidogrel) prevented the occurrence of both diastolic dysfunction and exercise intolerance in DhhECKO mice demonstrating for the first time that thrombosis may promote diastolic dysfunction. Importantly, we confirmed the critical role of thrombosis in Leprdb/db mice which also displayed increased cardiac small vessel thrombosis in comparison to control mice. Alike DhhECKO mice, we found that antiaggregants decreased EDP (6,3±0,4 mmHg in aspirin-treated vs 11,3 ± 0,79 in control mice; p=0,001) and improved exercise tolerance in Leprdb/db mice (34 ± 2,52 min in aspirin-treated vs 24 ± 3,55 in control mice; p=0,004). Conclusion Altogether, these results demonstrate that small vessel thrombosis may participate in the pathophysiology of heart failure with preserved ejection fraction.

Diastolic dysfunction is associated with cardiac small vessel disease in ovariectomized females but not in males

Abstract Introduction Coronary microvascular disease has been proposed to be responsible for heart failure with preserved ejection fraction (HFpEF) about 10 years ago. However, to date the role and phenotype of the coronary microvasculature has still been poorly considered and investigated in animal models of HFpEF. Objective To characterize the phenotype of the coronary microvasculature in male and female mice with diastolic dysfunction. Method We assessed cardiac function and characterized the coronary microvasculature in two mouse models of HFpEF: mice fed with a high fat diet (HFD) + L-NAME regimen and Leptin receptor deficient (Leprdb/db) mice. Notably, our study was done in males, females and ovariectomized (OVX) female mice in order to search for possible sexual dimorphisms. Results Upon a HFD + L-NAME regimen, both males and OVX females but not non OVX females develop diastolic dysfunction attested by an increased end diastolic pressure. In Leprdb/db mice, both Male and non OVX female mice develop diastolic dysfunction. Notably female mice have reduced estradiol and progesterone level mice mimicking ovariectomy. We found that both OVX and non OVX females but not males display increased endothelial activation attested by increased ICAM1 expression, endothelium leakage attested by increased Fibrinogen and IgG extravasation and decreased arteriole diameter suggesting vasoconstriction. The same results were found in Leprdb/db mice. Conclusion: Diastolic dysfunction is not always associated with cardiac small vessel disease since Leprdb/db males and C57BL/6J males fed with a high fat diet (HFD) + L-NAME regimen develop diastolic dysfunction in the absence of endothelial dysfunction. Also endothelial dysfunction may not be sufficient to induce diastolic dysfunction since non OVX female mice fed with a high fat diet (HFD) + L-NAME regimen display endothelial dysfunction while they do not develop diastolic dysfunction.

Long-acting CRF2 peptide agonist improves cardiac function in a rat heart failure model

Abstract Introduction Corticotropin-releasing factor receptor type 2 (CRF2) is a G protein-coupled receptor largely expressed in the cardiorenal system. Upon CRF2 activation, endogenous ligands such as urocortin-2 (UCN-2) or urocortin-3 (UCN-3) have been reported to increase cardiac function, decrease vascular resistance and improve natriuresis and diuresis in heart failure (HF) patients and in various experimental heart failure settings. However UCN-2 or -3 suffer from a very short half-life which markedly limit further clinical investigations in HF patients. For this purpose, a very long acting CRF2 peptide agonist has been developed. Objectives The aim of this study is to determine the acute effect on cardiac hemodynamic of a long acting CRF2 peptide agonist, COR-1167, in a rat model of chronic heart failure. Methods In 10-week-old Wistar rats, a total occlusion of the left anterior descending coronary artery was performed to induce myocardial infarction. Twelve weeks after myocardial infarction, rats had developed heart failure and received COR-1167 at the dose of 0.3 µg/kg or 1 µg/kg, or placebo, administered SC. Left ventricular dimensions and function were then assessed by echocardiography and left ventricular pressure-volume analysis. Results Three months after left coronary artery ligation rats displayed the classical features of heart failure as illustrated by an increase in left ventricular diastolic diameter and reduced ejection fraction, and decreases in LV end-systolic pressure, dP/dtmax and LV end-systolic pressure volume relationship. Major LV diastolic dysfunction developed, as shown by the increases in LV end-diastolic pressure, and LV end-diastolic pressure volume relationship and the decrease in dP/dtmin. Echocardiography and left ventricular pressure-volume analysis showed that COR-1167 at 0.3 and 1 µg/kg SC improved in a dose-dependent manner cardiac contractility and relaxation as assessed by LVESPVR and LVEDPVR, respectively. In addition, stroke volume and cardiac output were significantly ameliorated by COR-1167 at 1.0 µg/kg SC, with no change in heart rate. Conclusion Single acute administration of COR-1167 improved cardiac function in a rat model of heart failure with reduced ejection fraction. Altogether these results confirm that CRF2 agonism is an attractive therapeutic target for the treatment of heart failure.

Abstract P3107: Sexual Dimorphism In Diastolic Dysfunction And Cardiac Small Vessel Disease In Heart Failure With Preserved Ejection Fraction Mouse Models

Introduction: Coronary microvascular disease has been proposed to be responsible for heart failure with preserved ejection fraction (HFpEF) about 10 years ago. However, to date the role and phenotype of the coronary microvasculature has still been poorly investigated in animal models of HFpEF and sex differences are not always considered. Objective: To characterize the phenotype of the coronary microvasculature in male and female mice with diastolic dysfunction in two HFpEF mouse models. Method: We assessed cardiac function and characterized the coronary microvasculature in mice fed with a high fat diet (HFD) + L-NAME regimen and in Leptin receptor deficient ( Lepr db/db ) mice. Notably, our study was done in males, females and ovariectomized (OVX) female mice in order to search for possible sexual dimorphisms. Results: Upon a HFD + L-NAME regimen, both males and OVX females but not non OVX females develop diastolic dysfunction attested by an increased end diastolic pressure. In Lepr db/db mice, both Male and non OVX female mice develop diastolic dysfunction. Notably female mice have reduced estradiol and progesterone level mice mimicking ovariectomy. We found that both OVX and non OVX females but not males display increased endothelial activation attested by increased ICAM1 expression, endothelium leakage attested by increased Fibrinogen and IgG extravasation and decreased arteriole diameter suggesting vasoconstriction. The same results were found in Lepr db/db mice. Conclusion: Diastolic dysfunction is not always associated with cardiac small vessel disease since Lepr db/db males and C57BL/6J males fed with a high fat diet (HFD) + L-NAME regimen develop diastolic dysfunction in the absence of endothelial dysfunction. Also endothelial dysfunction may not be sufficient to induce diastolic dysfunction since non OVX female mice fed with a high fat diet (HFD) + L-NAME regimen display endothelial dysfunction while they do not develop diastolic dysfunction.

Abstract P2082: Thrombosis In The Coronary Microvasculature May Be Responsible For Impaired Cardiac Relaxation And Diastolic Dysfunction

Introduction: Heart Failure with Preserved Ejection Fraction (HFpEF) is proposed to be caused by endothelial dysfunction in cardiac small vessels. We previously identified Hhipl1,as a gene upregulated in the coronary vasculature of Leptin receptor deficient mice (Leprdb/db) a well-established mouse model of HFpEF. Importantly, Hhipl1 encodes for a decoy receptor of Desert Hedgehog (DHH) which is known to be critical for endothelial integrity. Objective: Our objective is to investigate the functional consequences of impaired Hedgehog (HH) signaling in the adult heart in order to identify novel mechanisms underlying the development of diastolic dysfunction. Method: Cdh5-Cre/ERT2, DhhFlox/Flox (DhhECKO) mice and their control littermates were administered with tamoxifen at 8 weeks of age to induce Dhh KO. Their cardiac function, exercise tolerance, and the phenotype of their coronary vasculature were assessed one month later. Results: DhhECKO mice presented significantly reduced exercise tolerance, increased end diastolic pressure (EDP) and Tau, with no change in their ejection fraction consistent with diastolic dysfunction. At molecular and cellular level, impaired cardiac relaxation in DhhECKO mice was associated with a significantly decreased phospholamban phosphorylation on Thr17 and an alteration of sarcomeric shortening in ex-vivo. Besides, as expected, DhhECKO mice exhibited phenotypic changes in their coronary vasculature including a prominent pro-thrombotic phenotype leading to an impaired capillary perfusion and local hypoxia. Notably, antiaggregant therapies (aspirin and clopidogrel) prevented the occurrence of both diastolic dysfunction and exercise intolerance in DhhECKO mice demonstrating for the first time that thrombosis may promote diastolic dysfunction. Importantly, we confirmed the critical role of thrombosis in Leprdb/db mice which also displayed increased cardiac small vessel thrombosis in comparison to control mice. Alike DhhECKO mice, we found that antiaggregants decreased EDP and improved exercise tolerance in Leprdb/db mice. Conclusion: Altogether, these results demonstrate that small vessel thrombosis may participate in the pathophysiology of heart failure with preserved ejection fraction.

Diastolic dysfunction is associated with cardiac small vessel disease in ovariectomized females but not in males

Coronary microvascular disease has been proposed to be responsible for heart failure with preserved ejection fraction (HFpEF) about 10 years ago. However, to date the role and phenotype of the coronary microvasculature have still been poorly considered and investigated in animal models of HFpEF. To characterize the phenotype of the coronary microvasculature in male and female mice with diastolic dysfunction. We assessed cardiac function and characterized the coronary microvasculature in two mouse models of HFpEF: mice fed with a high fat diet (HFD) + L-NAME regimen and Leptin receptor deficient (Leprdb/db) mice. Notably, our study was done in males, females and ovariectomized (OVX) female mice in order to search for possible sexual dysmorphism. Upon a HFD + L-NAME regimen, both males and OVX females but not non OVX females develop diastolic dysfunction attested by an increased end diastolic pressure. In Leprdb/db mice, both male and non OVX female mice develop diastolic dysfunction. Notably, female mice have reduced estradiol and progesterone level mice mimicking ovariectomy. We found that both OVX and non OVX females but not males display increased endothelial activation attested by increased ICAM1 expression, endothelium leakage attested by increased Fibrinogen and IgG extravasation and decreased arteriole diameter suggesting vasoconstriction. The same results were found in Leprdb/db mice. Diastolic dysfunction is not always associated with cardiac small vessel disease since Leprdb/db males and C57BL/6 J males fed with a high fat diet (HFD) + L-NAME regimen develop diastolic dysfunction in the absence of endothelial dysfunction. Also endothelial dysfunction may not be sufficient to induce diastolic dysfunction since non OVX female mice fed with a high fat diet (HFD) + L-NAME regimen display endothelial dysfunction while they do not develop diastolic dysfunction.

Contemporary Management Strategies of Baffle Leaks in Adults with a Failing Systemic Right Ventricle Late after Atrial Switch: A Case Series and Literature Overview

Baffle leaks are a frequently encountered and often overlooked complication after the atrial switch procedure for transposition of the great arteries. Baffle leaks are present in up to 50% of non-selected patients, and while they initially may not cause clear symptoms, they can complicate the hemodynamic course and influence the prognosis in this complex patient group. A shunt from the pulmonary venous atrium (PVA) to the systemic venous atrium (SVA) can lead to pulmonary overflow and subpulmonary left ventricular (LV) volume overload, while a shunt from the SVA to the PVA can result in (exercise-associated) cyanosis and paradoxical embolism. We report three cases of baffle leaks in patients with systemic right ventricular (sRV) failure late after the atrial switch procedure. Two symptomatic patients who presented with exercise-associated cyanosis due to SVA to PVA shunting over the baffle leak underwent successful percutaneous baffle leak closure with a septal occluder device. One patient with overt sRV failure and signs of subpulmonary LV volume overload due to PVA to SVA shunting was managed conservatively, as baffle leak closure was expected to lead to an increase in sRV end-diastolic pressure and aggravation of sRV dysfunction. These three cases illustrate the considerations made, challenges faced, and necessity of a patient-tailored approach when addressing baffle leaks.

Transient Increase in the Terminal Negative Deflection of the P Wave in Lead V1 during Treadmill Testing Identifies Exercise Induced Aggravated Left Ventricular Dysfunction

Terminal negative deflection of the P wave in lead V1 is produced by posteriorly directed depolarization of the left atrium. A value of more than 0.04 mm sec suggests increase in left atrial pressure. Transient new appearance of this finding during treadmill testing suggests transient exercise induced increase in left atrial pressure. Indirectly it suggests transient exercise induced/aggravated increase in left ventricular end diastolic pressure. In presence of clinical and/or electrocardiographic findings of myocardial ischemia, this finding suggest ischemia induced left ventricular dysfunction. Earlier this finding appears during exercise and longer it lasts during recovery, more severe is the left ventricular dysfunction.

A total closed chest swine model of acute myocardial infarction-related cardiogenic shock: A critical double coronary sub-occlusion approach

The management of acute myocardial infarction-related cardiogenic shock (AMICS) represents a significant challenge, with mortality rates remaining high (40–60%), despite recent advances. Current animal models of myocardial infarction are either associated with a very high rate of per-procedure malignant arrhythmia, or with very low impairment of hemodynamic parameters, or with the inability to have complete coronary reperfusion. We sought to develop a closed chest and clinically relevant large animal model of severe AMICS, with high survival rate. Adult pigs were anaesthetized and mechanically ventilated. Percutaneous cardiac catheterization was performed under fluoroscopy. Advanced left ventricular dysfunction was induced by 120 minutes of critical sub-occlusion of the proximal left anterior descending coronary artery and the mid circumflex artery. A thorough hemodynamic assessment was obtained by invasive and non-invasive monitoring devices. Repeated blood samples were obtained to determine blood gas parameters, lactate, and haemoglobin concentration. After death, the heart was retrieved for further histological analyses. All animals (n = 12) developed significant circulatory failure associated with AMICS upon reperfusion and beyond. No animal died during the ischemia process. However, all animals that did not benefited from vasopressor support (“sham” group, n = 4) spontaneously died within 30 minutes of reperfusion, confirming the severity of the model. Cardiogenic shock was characterized by a drop in mean arterial pressure below 60 mmHg (58 ± 5 mmHg at 120 min of ischemia), a significant decrease in mean cardiac output (−44% from 5.7 ± 0.4 at baseline to 3.2 ± 0.4 at 120 minutes of ischemia) and SvO2 (−32% from 57 ± 8 at baseline to 39 ± 6 at 120 minutes of ischemia) and a significant increase in left ventricle end-diastolic pressure (LVEDP) (+110% from 10 ± 3 at baseline to 21 ± 3 at 120 minutes of ischemia). CO2 gap and coronary sinus venous oxygen saturation increased significantly upon ischemia and reperfusion and remained elevated throughout (P ≤ 0.001 for all comparisons). Myocardial samples corroborated extensive cellular necrosis and inflammatory infiltrates. We present, for the first time, a stable and clinically relevant model of severe AMICS obtained by critical double coronary sub-occlusion. The greater severity of the model did not lead to an increase in the frequency of malignant arrythmias and per-procedure mortality.

Abstract 15530: Renal Outer Medullary Potassium (Kir 1.1) is not the Kir Subunit of a Cardioprotective, Diazoxide - Mediated Mitochondrial Adenosine Triphosphate - Sensitive Potassium Channel

Objective: The adenosine triphosphate-sensitive potassium (K ATP ) channel opener diazoxide (DZX) mimics ischemic preconditioning and is cardioprotective. The molecular mechanism of action is unknown, although several mitochondrial candidate protein targets have been proposed. We suggested that cardioprotection occurs at a non-sarcolemmal channel, requires the inhibition of succinate dehydrogenase, and involves K ATP channel subunit SUR1. The renal outer medullary potassium channel (ROMK, or Kir1.1) subunit was proposed as the Kir subunit of a mitochondrial (m)K ATP channel. We tested the hypothesis that genetic deletion of ROMK will result in loss of DZX cardioprotection in a model of prolonged ischemia with cardioplegia. Methods: Mice lacking ROMK in cardiac myocytes (cKO) and wild-type (WT) litter mates were randomly assigned to 90 min. global ischemia in a Langendorff model following hypothermic hyperkalemic cardioplegia (CPG) or CPG + DZX (100 μM/L) (N=6-9 per group). Left ventricular developed pressure (LVDP), end diastolic pressure (EDP), and coronary flow were compared before and after global ischemia. Data acquisition and interpretation were blinded to group. Results: Similar to previous results, prolonged global ischemia was associated with a reduction in LVDP and an increase in EDP with CPG that was prevented by DZX in WT. Unexpectedly, ROMK (cKO) mice were equally responsive to DZX (Figure), indicating that DZX protection is not mediated by ROMK channels. Conclusions: Genetic deletion of ROMK in cardiac myocytes does not negate cardioprotection provided by DZX, indicating ROMK is not a subunit of a cardioprotective mK ATP channel. Alternate proposed DZX-sensitive target channels or mechanisms of action remain to be tested. Identification of the specific subunits of a mK ATP channel would allow for targeted pharmacologic therapy to reduce myocardial stunning following prolonged ischemia, similar to that seen following cardiac surgery.

Diastolic dysfunction in late postmenopausal patients with undifferentiated connective tissue disease and hypertension

Aim. To assess myocardial diastolic function (DF) in late postmenopausal women with undifferentiated connective tissue disease (UCTD) and hypertension (HTN).Material and methods. This cross-sectional study included 135 postmenopausal women, the median age of which was 68 years (65÷70,5 years). The anamnesis was collected using a standardized questionnaire. Verification of UCTD was carried out according to clinical guidelines. All patients underwent standard transthoracic echocardiography. The assessment of left ventricular (LV) DF was carried out according to the transmitral flow. LV diastolic dysfunction (DD) was classified into three types: rigid, pseudonormal, and restrictive. Statistical processing was carried out in the STATISTICA 13.0 environment. The measure of data averaging is the median, the measure of dispersion is 25%÷75%. The significance of differences was assessed using the Mann-Whitney test. Differences were considered significant at p˂0,05.Results. Group 1 — 20 (14,8%) patients with verified UCTD and HTN, group 2 — 88 (65,2%) patients with HTN without UCTD, control group — 23 (30%) patients without HTN and UCTD. There were no differences in age, duration of postmenopause and body mass index between the groups. In the first group, a significant decrease in the ratio of peak early to late diastolic LV filling velocity was revealed (p˂0,01). A significant increase in left ventricular end-systolic wall stress revealed in group 1. In 108 (100%) patients, LVDD was detected; among the patients of the control group, DD was not detected. In 8 (40%) patients in group 1, a pseudo-normal type of DD was detected, while in 12 out of 20 patients (60%) — rigid type of DD. When assessing DF in patients of group 2, a significant decrease was found in the ratio of peak early to late diastolic LV filling velocity, a significant increase in LV end-diastolic wall stress and end-diastolic pressure. In 2 out of 3 (57,80%) patients of group 2, DD of the rigid type was detected, while pseudonormal type — in 32,2% of patients in this group. Group 2 patients had a significant decrease in the early diastolic mitral annular velocity (p˂0,01).Conclusion. The analysis of myocardial echocardiographic characteristics indicates a significant contribution of HTN-associated UCTD to the development of LVDD in postmenopausal women.

A transgenic mouse model mimicking human cardiac amyloidosis

Abstract Background Heart failure (HF) pathophysiology complicating cardiac amyloidosis (CA) is poorly explored due to the lack of relevant animal model. A recently transgenic mouse expressing an amyloidogenic variant of human apolipoprotein AII was developed that showed ubiquitous amyloid deposit but limited data on cardiac involvement. Purpose To investigate heart structure and function in transgenic mice expressing an amyloidogenic variant of human apolipoprotein AII Methods Seventy-nine mice ageing 2 to 3 months were included in this study as follow: amyloidosis group (n=44) and sham (i.e. genetic mutation without phenotypic expression, n=35). Both were serially imaged by echocardiography (Vevo3100 Fujifilm) and cardiac magnetic resonance imaging (CMR, Biospec 4.7 tesla), and invasively explored by left–sided catheterization (pressure-volume loop [PV loop], Millar Catheterization), before sacrifice and histological investigations. Results As soon as 2–3 months of age, the amyloidosis group demonstrated significant left ventricular (LV) hypertrophy, diastolic dysfunction and left atrial dilatation compared with sham group (p<0.01). Left ventricular ejection fraction was initially normal in both groups but deteriorated in amyloidosis mice (p<0.001) before right ventricular function collapses (p<0.001). In amyloidosis group, PV loops showed significant LV end-diastolic pressure increase (p<0.001), stiffer LV (p<0.01) and reduced systolic function LV elastance (p<0.05). Invasive and non-invasive abnormalities paralleled severe CA deposits and subendocardial fibrosis matrix remodeling, both labeling by Congo red and Red Sirius coloration (p<0.001). CMR analysis showed significant T1 (p<0.05) and T2 (p<0.01) signal increase and significant decrease in myocardial perfusion (p<0.01) in the amyloidosis group. Clinically, mice with amyloidosis covered less distance during exercise test (p<0.001) and died earlier (log-rank test, p<0.01). Conclusion By mimicking human cardiac amyloidosis, the model of transgenic mouse expressing an amyloidogenic variant of human apolipoprotein AII is promising to investigate the underlying pathophysiology of heart failure due to amyloidosis. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Pfizer grant

Dissecting the progression of cardiac dysfunction in tumor-bearing mice

Abstract Funding Acknowledgements Type of funding sources: None. Background Cancer patients undergoing heart-related complications result in high incidences of mortality. Nevertheless, it is still not fully understood whether localized tumors affect heart function prior to the onset of cachexia, hence, making the heart more vulnerable for functional abnormalities in later stages of the disease. In addition to analyse heart function, we focus on the expression BCL-2–associated athanogene 3 (BAG3), a co-chaperone protein and Hsp70, which are highly expressed in tumor but decrease in cardiomyocytes (CM) in heart failure (HF). Methods Colon-26 adenocarcinoma cells (C26; n=22) with/without shIL-6 (C26 shIL-6; n=22) were injected subcutaneously into the right flank of 10-11 weeks old BALB/c male mice. Control mice were injected with vehicle (PBS; n=8). Cardiac function was assessed by echocardiography and invasive hemodynamic measurements 10 (early) and 20 (late) days after the injection, respectively. In addition, the expression of BAG3 and Hsp70 were determined by Western blot as well as the extend of cardiac fibrosis was determined by Masson-Goldner's trichrome staining. Results The tumor size was comparable between the two injected groups. However, only C26 group showed a significant loss of subcutaneous fat and skeletal muscle (p<0.05, respectively), suggesting cachexia. Heart weight normalized to tibia length was not changed in the injected groups as compared to controls (day 20). However, left ventricular ejection fraction (LVEF) showed a tendency to decline in the early phase (p~0.08) in both injected group and it reached significance at late stage (p<0.05). Invasive hemodynamic assessment also confirmed the contractile dysfunction, resulting in a decrease in LV systolic pressure and increase of LV end-diastolic pressure (p<0.05, respectively). Importantly, these functional changes in the heart in tumor-bearing mice were associated with a marked reduction in both BAG3 and Hsp70 in the myocardium. Furthermore, there was no sign of cardiac fibrosis in the injected groups. Discussion Our study shows for the first time that tumor rather than cancer cachexia plays a significant maladaptive role in the progression of cardiac dysfunction in a mouse model of C26 injection-induced cachexia. The progression of cardiac contractile dysfunction was associated with a decline in BAG3 and Hsp70 in tumor-bearing mice, suggesting changes of BAG3/Hsp 70 signalling may be a critical component as well as target.

Endothelial protection does not prevent diastolic dysfunction in high fat diet + L-NAME treated mice

Schiattarella et al. introduced a new mouse model mimicking heart failure with preserved ejection fraction (HFpEF). In this model, diastolic dysfunction is induced by a high fat diet (HFD) regimen with L-NAME treatment. Small vessel disease is currently proposed to be responsible for HFpEF. Moreover, blocking Cdon, a negative co-receptor of Hedgehog signalling pathway, in endothelial cells in mice promote endothelium integrity in inflammatory conditions. Consequently, CdonECKO mice represent a good model of endothelial protection. To determine whether prevent endothelial dysfunction prevent diastolic dysfunction. Ovariectomized CdonECKO female mice were fed with HFD from 8 weeks of age. L-NAME treatment was initiated 2 weeks later. Cardiac function was assessed via echocardiography and left ventricle (LV) catheterization at 20 weeks of age. Immediately after, mice were sacrificed for histological and gene expression analyses. Consistently with our previous results, CdonECKO mice treated with HFD and L-NAME display a decreased permeability, a decreased expression of ICAM1 and a decreased infiltration of CD45+ leukocytes compared to their controls. Capillary density and mural cell coverage were not modified. Despite their endothelial improvement, mice displayed increased end diastolic pressure with a preserved LV ejection fraction. Diastolic dysfunction was associated with cardiac hypertrophy and fibrosis as in their controls. Prevention of endothelial dysfunction observed in HFpEF mice models does not prevent diastolic dysfunction in HFD + L-NAME treated mice supporting that small vessel disease is not the only key factor in the pathophysiology of HFpEF.

Ubiquitin Carboxyl-Terminal Hydrolase L1 of Cardiomyocytes Promotes Macroautophagy and Proteostasis and Protects Against Post-myocardial Infarction Cardiac Remodeling and Heart Failure.

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a deubiquitinase known to play essential roles in the nervous tissue. Myocardial upregulation of UCHL1 was observed in human dilated cardiomyopathy and several animal models of heart disease, but the (patho)physiological significance of UCHL1 in cardiomyocytes remains undefined. Hence, we conducted this study to fill this critical gap. We produced cardiomyocyte-restricted Uchl1 knockout (CKO) by coupling the Uchl1-floxed allele with transgenic Myh6-Cre in C57B/6J inbred mice. Mice transgenic for Myh6-Cre were used as controls (CTL). Myocardial Uchl1 proteins were markedly reduced in CKO mice but they did not display discernible abnormal phenotype. Ten-week old CTL or CKO mice were subjected to left anterior descending artery ligation (myocardial infarction, MI) or sham surgery (Sham) and characterized at 7- and 28-day after surgery. Compared with Sham mice, significant increases in myocardial UCHL1 proteins were detected in CTL MI but not in CKO MI mice. MI-induced left ventricular (LV) chamber dilation, reduction of ejection fraction (EF) and fractional shortening (FS), and LV anterior wall thinning detected by echocardiography were comparable between the CTL MI and CKO MI groups 7-day post-MI. However, by 28-day post-MI, MI-induced LV chamber dilatation, EF and FS reduction, increases of myocardial ubiquitin conjugates, and increases in the heart weight to body weight ratio and the ventricular weight to body weight ratio were significantly more pronounced in CKO MI than CTL MI mice. As further revealed by LV pressure-volume relationship analyses, CKO MI mice but not CTL MI mice displayed significant decreases in stroke volume, cardiac output, and the maximum rates of LV pressure rising or declining and of LV volume declining, as well as significant increases in LV end-diastolic pressure and Tau, compared with their respective Sham controls. LC3-II flux assays reveal that autophagic flux is decreased in CKO mouse myocardium as well as in cultured Uchl1-deficient cardiomyocytes. In conclusion, UCHL1 of cardiomyocytes is dispensable for development but promotes macroautophagy in cardiomyocytes. Upregulation of UCHL1 in post-MI hearts occurs primarily in the cardiomyocytes and protects against post-MI cardiac remodeling and malfunction likely through supporting autophagic flux and proteostasis during a stress condition.

Exercise Training Attenuates Cardiac Vulnerability and Promotes Cardiac Resistance to Isoproterenol-Induced Injury Following Hookah Smoke Inhalation in Male Rats: Role of Klotho and Sirtuins.

Hookah smoking is on the rise around the world. Present study investigated the heart resistance to harmful stress following long-term waterpipe tobacco smoking (WTS) and moderate-intensity exercise training intervention in male Wistar rats. Animals were randomly divided into a non-ischemic heart control group and four ischemic heart groups including ISO (isoproterenol-treated), Ex + ISO (subjected to exercise plus ISO), S + ISO (exposed to hookah smoke plus ISO), and Ex + S + ISO (subjected to exercise along with hookah smoke plus ISO). After eight weeks of training and WTS, heart ischemia induced by isoproterenol injections. Then, cardiac functional indices and some biochemical and histopathological parameters were assessed. WTS + ISO reduced systolic pressure, ± dP/dt max, and contractility indices (P < 0.001 vs. ISO group) and increased end diastolic pressure and Tau index (P < 0.001 vs. ISO) of the left ventricle. Also, WTS + ISO was associated with an increase in Bax protein level and Bax/Bcl-2 ratio (P < 0.05 and P < 001, respectively, vs. ISO group) as apoptotic markers of heart tissue. Hookah smoke significantly decreased SIRT1 (P < 0.05 and P < 0.001, respectively, vs. ISO) and klotho (P < 0.01 and P < 0.001, respectively, vs. ISO) in serum and heart, and SIRT3 and pS9-GSK-3β (P < 001 and P < 0.05, respectively, vs. ISO) in heart tissue. Combination of exercise with WTS prevented the hookah smoke-induced alterations in apoptotic markers, cardiac functional indices, and SIRT1, SIRT3, klotho, and pS9-GSK-3β proteins. The findings demonstrated that hookah smoke inhalation intensifies ventricular dysfunction and decreases heart resistance to harmful stresses. Moderate-intensity exercise training attenuated these complications partly through recovering the klotho and sirtuins levels and apoptosis-survival balancing.