Ventricular Pressure Research Articles

Abstract 2131: Bone Marrow-derived Macrophages May Contribute To Elevation Of Et-1 And Pulmonary Hypertension In Female Bmpr2 +/r899x Mutant Mice

Introduction: Mutation that causes loss of function of bone morphogenetic protein receptor 2 (BMPR2) has been implicated in the pathogenesis of Pulmonary Arterial Hypertension (PAH), a disease that currently has no cure and is characterized by elevated right ventricular systolic pressure and right ventricle hypertrophy. Females experience thrice more incidence of PAH. Elevation in the expression of ET-1, Endothelin-1, has been linked to the development of PAH. It is unclear what is contributing to the elevation of ET-1 observed in female mutants. Hypothesis: Macrophage activation in the microvasculature contributes to ET-1 elevation and PH pathogenesis in female BMPR2 +/R899X mice. Materials/Methods: Lung samples from 12-month-old male and female wild-type and BMPR2 +/R899X mutants were used for analysis of the ET-1 expression via Western Blot (WB). Accumulation of CD45+ET-1+ cells in the lungs was evaluated by immunohistochemistry (IHC). Finally, bone marrow-derived macrophages (BMDM) isolated from male and female mutant mice underwent a 24-hour treatment with 100 ng/mL Lipopolysaccharide (LPS) and vehicle (control) and ET-1 expression was measured in the cell lysate by WB. Results/Discussion: In exploring the source of ET-1, our initial findings indicated an accumulation in inflammatory perivascular cells. A double-blind analysis of the CD45 pan-leukocyte marker revealed a substantial increase in CD45+ cells in female mutants (4.09 +/- 0.68 and 10.46 +/- 1.15 CD45+ cells/microvessel, male and female, respectively; 8 micrographs/animal; 3 mice/group). Colocalization between CD45+ cells and ET-1 suggests these cells may be a source or contribute to ET-1 clearance in the lungs of female mutants. While the identity of CD45+ cells remain unclear, their morphology suggests they are likely macrophages. Indeed, preliminary results indicate a significant rise in ET-1 expression in BMDM from female mutants at baseline and upon LPS exposure. Conclusion: Accumulation of CD45+ cells in female mutant lungs, along with colocalization with ET-1, may contribute to PAH development. Additionally, increased ET-1 expression in macrophages from female mutant mice suggests macrophage activation as a potential factor in ET-1 elevation in female mutant lungs.

Sex Dependent Exacerbation of Salt Sensitive Hypertension and Cardiac Dysfunction Is Associated With Upregulation of miRNA Targeting ADAM17 and ACE2 in the Brain

Background: The DOCA-salt model has been widely used to study salt-sensitive hypertension and we previously reported that it is associated with ADAM17-mediated ACE2 shedding in the central nervous system. However, previously reported data are mainly from male mice, and it is unclear whether female mice exhibit the same phenotypes. Objective: We aimed to compare sex specific development of salt sensitive hypertension and cardiac dysfunction and investigate miRNA regulation associated with these changes. Methods: C57 mice (male and females, n = 8 -15) underwent uninephrectomy and telemetry implantation (DSI Inc.) for blood pressure (BP) conscious recording. After baseline recording, a DOCA pellet (50 mg, 21 days, Innovative Research of America) was implanted subcutaneously and drinking water was replaced by 1% NaCl solution to induce salt sensitive hypertension. Cerebral Spinal fluid (CSF) was collected at baseline and after 3 weeks of DOCA-salt treatment for exosome miRNA sequencing (Creative Biolab). In another set of mice, cardiac function was assessed by echocardiography (Visualsonics Vevo F2) and invasive left ventricular hemodynamics (Transonic). Mortality from each group was analyzed as well. Results: Baseline BP was not different between male and female mice. Following DOCA-salt treatment for 3 weeks, BP was increased in both sexes, with higher systolic BP observed in males compared to females (active phase: 173.0 ± 19.6 vs. 154.2 ± 19.1 mmHg, p<0.05). Although ejection fraction was not changed in either male or female mice, mitral peak early diastolic filling velocity and tissue doppler showed that E/E’ was increased in both sexes compared to baselines (Male: 33.4 ± 4 vs. 26.6 ± 1.9; Female: 30.3 ± 5.0 vs. 26.4 ± 4), with a greater increase in males (25.3% vs. 14.4%). In addition, hemodynamics revealed increased left ventricular end-diastolic pressure (11.1 ± 1.9 vs. 4.5 ± 0.5 mmHg, p<0.01) and relaxation time constant Tau (6.7 ± 1.0 vs. 4.9 ± 0.5 msec, p<0.01) in DOCA-salt treated males compared to non-treated controls, with no changes shown in female mice. These data suggest worsened cardiac diastolic function in males compared to females following DOCA-salt treatment. Moreover, a 20% mortality was observed in males while no death occured in females, confirming a more severe phenotype in males. Furthermore, miRNAseq analysis of CSF exosomes showed several upregulated miRNA in males but not in females following DOCA-salt treatment. Notably, miR206 associated with increased ADAM17 activity was increased by 8-fold in males but only 3-fold n females. Conclusion: DOCA-salt treatment promotes exacerbated hypertension, impaired cardiac function and mortality in a sex dependent manner, associated with upregulation of key miRNA targeting the brain renin-angiotensin system. The changes of ADAM17 and ACE2 targeted exosome miRNAs in the central nervous system might contribute to the sex difference in the cardiovascular dysfunction phenotypes in this model. This work was supported in part by a research grant from the National Institutes of Health (HL163588). 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.

ECHOCARDIOGRAPHIC AND ELECTROCARDIOGRAPHIC PREDICTORS OF NEW ATRIAL FIBRILLATION IN END-STAGE RENAL DISEASE PATIENTS WITH PRESERVED LEFT VENTRICULAR SYSTOLIC FUNCTION

Objective: We investigated the echocardiographic and electrocardiographic predictors for future development of AF in patients with ESRD and preserved LV EF who had never diagnosed AF. Design and method: Atrial fibrillation (AF) is a common cause which leads to adverse cardiovascular outcome in patients with end-stage renal disease (ESRD). AF is common arrhythmia in patients with reduced left ventricular (LV) ejection fraction (EF). It is unclear the predictor of new AF in patients with preserved LV EF. We enrolled 226 patients with ESRD who has performed transthoracic echocardiography. We excluded the 1) 16 patients who has been received a diagnosis of AF, and 2) 19 patients with LV EF < 50%, and 191 patients (121 males, mean 62 ± 14 years) Results: During a mean follow-up period of 885 ± 720 days, AF occurred in 20 (10.5%) patients. The patients with AF development was older (69 ± 12 vs. 61 ± 14 years, p=0.023). There were no differences in history of hypertension, diabetes, stroke and coronary artery disease between two groups. In univariate Cox regression analysis, left atrial volume index (LAVI), right ventricular systolic pressure, age and QRS duration were associated with future AF events. After multivariate Cox regression analysis, age (HR: 1.015, 95% CI: 1.008-1.105, p value: 0.022) and QRS duration (HR: 1.025, 95% CI: 1.001-1.049, p value: 0.043) significantly predicted the future development of AF. Conclusions: QRS duration is well known predictor of cardiovascular outcome in patients with reduced LV EF. In this study, we demonstrated QRS duration predicted new AF events in ESRD patients with preserved LV EF.

Naltrindole attenuates irreversible Hypercontracture during Myocardial Ischemia by a Novel Mechanism and elicits robust cardioprotective effects in Myocardial Ischemia/Reperfusion Injury

Introduction: Previous studies have shown that naltrindole (NTI) produced robust cardioprotective effects (e.g.~80% reduction of infarct size) in both ex-vivo (2.5-5μM) and in-vivo (3.75-7.5 mg/kg) rat myocardial ischemia-reperfusion (MIR) injury models. We recently showed that NTI 100-200μM attenuated phorbol 12-myristate 13-acetate (PMA) induced polymorphonuclear leukocytes (PMNs) superoxide (SO) release by a novel mechanism of action (MOA) devoid of opioid receptors. We hypothesize NTI’s novel MOA is a reduction of intracellular calcium (Ca2+). To test this hypothesis, we conducted PMN SO release and isolated perfused MIR assays using KB-R7943(KB). KB is known to reduce intracellular Ca2+ via inhibition of reverse mode Na+/Ca2+ exchanger and therefore should attenuate PMN SO release, myocardial ischemic hypercontracture, infarct size, and left ventricular end diastolic pressure (LVEDP). Methods: PMNs and hearts isolated from anesthetized male Sprague Dawley (SD) rats (~400g SO release assay, ~300g for perfused hearts). PMN SO release was stimulated using PMA (100nM) ± NTI 10-200 μM, KB 5-20 μM, or vehicle (0.5% DMSO; controls) and measured spectrophotometrically as a change in absorbance @ 550nm over 390 secs and cell viability was determined using 0.2% Trypan blue exclusion. We then infused NTI 1.25-5μM, KB 10-20μM, or naloxone (NX; negative control) 10μM for 5 min into perfused hearts, just prior to global I (30min)/R(45min). Cardiac LV function was measured via a pressure transducer and infarct size using 1% triphenyltetrazolium chloride staining in MIR assay. Data were analyzed using ANOVA and Fischers post-hoc analysis, with p<0.05 considered statistically significant. Results: PMN SO release assay: KB 10 μM, KB 20 μM, NTI 100 μM (~3.75 mg/kg), and NTI 200 μM(~7.5 mg/kg) significantly attenuated PMA induced PMN SO release by ~40% (KB 10μM, n=7, p<0.05), ~50% ((KB 20μM, n=7, p<0.05), ~30% (NTI 100 μM, n=7, p<0.05), 75% (NTI 200μM, n=7, p<0.05) respectively when compared to untreated control (n=10). MIR assay: NTI 5μM, 2.5μM, 1.25μM and KB 20 μM reduced infarct size (4.8±3%, n=5, p<0.05), (6.8±0.8%, n=6, p<0.05), (12.2±3%, n=5), and (2.9±2%, n=5, p<0.05) respectively compared to vehicle (14.1±2%, n=9) and NX 10μM controls (18±3%, n=3). NTI 5 μM and KB 20 μM had significantly improved LVEDP to (32.4±11%, n=5, p<0.05) and (22.8±4%, n=5, p<0.05) respectively compared to vehicle control (72.4±6%, n=9) and NX 10μM controls(54.2±8%, n=3) Conclusion: NTI and KB showed concentration-dependent effects on reducing PMN SO release. Both NTI (2.5μM, 5μM) and KB (20μM) reduced infarct size and improved LVEDP. The novel MOA of NTI is most likely mediated via a reduction in intracellular Ca2+ and subsequent hypercontracture during myocardial ischemia. The infarct reducing effect of NTI can benefit patients who will undergo elective PCI, CABG, and transplants. Funding: This study was funded by the Philadelphia College of Osteopathic Medicine, Department of Biomedical Sciences, Division of Research, and the Center for Chronic Diseases of Aging and Young Therapeutics, LLC. 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.

B-18 | Elevated Right Ventricular Systolic Pressure is an Independent Predictor of Mortality in Pediatric Pulmonary Vein Stenosis

B-18 | Elevated Right Ventricular Systolic Pressure is an Independent Predictor of Mortality in Pediatric Pulmonary Vein Stenosis

Role of aortic valve replacement in moderate aortic stenosis: a 10-year outcomes study

ObjectivePatients with moderate aortic stenosis (AS) exhibit high morbidity and mortality. Limited evidence exists on the role of aortic valve replacement (AVR) in this patient population. To investigate the benefit...

Sex Differences in Alcohol-related Cardiomyopathy

Alcohol-related Cardiomyopathy (ACM) manifests in humans with a significant history of alcohol use and is characterized by ventricular dilation and cardiac function impairment. Although the most common age group for ACM is males between the ages of 30-55, women require a lesser lifetime alcohol exposure to develop ACM than men. The objective of this study is to assess sexual differences in a mouse model of chronic plus binge alcohol consumption. We hypothesize that female mice exposed to chronic plus binge alcohol will not develop as severe cardiac dysfunction as their male counterparts. In this study, male (n=19) and female (n=14) C57BL/6J mice were provided chronic plus binge alcohol feeding. After 5 days of acclimation to the liquid diet, mice are fed ad libitum 5% ethanol (EtOH) liquid or isocaloric control liquid diet for 30 days. At 10 and 30 days, mice received an oral binge dose of EtOH (5 g/kg body weight), or isocaloric maltose dextrin solution (9 g/kg body weight). Noninvasive cardiac structural and functional data were obtained via echocardiography at baseline and following binges. After 30 days, cardiac hemodynamics was measured by open chest left ventricle catheterization. Two-way ANOVA with Tukey’s post hoc analysis was performed for each cardiac parameter, and significance was defined as p<0.05. Male EtOH mice exhibited a significant decrease in stroke work (1119 ± 297 mmHg/mL when compared to male controls, 1622 ± 365 mmHg/mL; p= 0.03). Female EtOH mice had a nonsignificant decrease in stroke work (1242 ± 374 mmHg/mL when compared to female controls, 1423 ± 469 mmHg/mL; p= 0.80). Maximum left ventricular pressure was decreased 20% in male EtOH mice (p=0.003) but increased 10% in female EtOH mice (p=0.46). The maximum rate of pressure change within the ventricle was 24% lower in the male EtOH mice (p=0.02) and 9% higher in female EtOH mice (p=0.87). The minimum rate of pressure change within the ventricle was 24% higher in male EtOH mice (p=0.02) and 17% lower in female ETOH mice (p=0.44). After 30 days of EtOH exposure, male mice showed significant systolic and diastolic dysfunction. Female mice on the other hand, did not show substantial cardiac dysfunction after chronic plus binge ethanol exposure. Further experiments involving qPCR of proinflammatory and profibrotic markers will elucidate the molecular mechanism of sex differences in ACM development. R21AA029747 (JG & CB) & T32AA007577. 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.

LOXL2 inhibition ameliorates pulmonary artery remodeling in pulmonary hypertension

Background: Conduit pulmonary arterial stiffening and the resultant increase in pulmonary vascular impedance has emerged as an important underlying driver of pulmonary arterial hypertension (PAH). Given that matrix deposition is central to vascular remodeling, we evaluated the role of the collagen crosslinking enzyme lysyl oxidase like 2 (LOXL2) in this study. Methods and Results: Human pulmonary artery smooth muscle cells (PASMCs) subjected to hypoxia showed increased LOXL2 secretion. LOXL2 activity and expression were markedly higher in primary PASMCs isolated from pulmonary arteries of the rat Sugen 5416 + hypoxia (SuHx) model of severe PH. Similarly, LOXL2 protein and mRNA levels were increased in pulmonary arteries (PA) and lungs of rats with PH (SuHx and monocrotaline (MCT) models). Pulmonary arteries (PAs) isolated from rats with PH exhibited hypercontractility to phenylephrine and attenuated vasorelaxation elicited by acetylcholine, indicating severe endothelial dysfunction. Tensile testing revealed a a significant increase in PA stiffness in PH. Treatment with PAT-1251, a novel small-molecule LOXL2 inhibitor, improved active and passive properties of the PA ex vivo. There was an improvement in right heart function as measured by right ventricular pressure volume loops in-vivo with PAT-1251. Importantly PAT-1251 treatment ameliorated PH, resulting in improved pulmonary artery pressures, right ventricular remodeling, and survival. Conclusion: Hypoxia induced LOXL2 activation is a causal mechanism in pulmonary artery stiffening in PH, as well as pulmonary artery mechanical and functional decline. LOXL2 inhibition with PAT-1251 is a promising approach to improve pulmonary artery pressures, right ventricular elastance, cardiac relaxation, and survival in PAH. This work was supported by a NHLBI grant R01HL105296 (to D.E.B.), a NHLBI grant R01HL148112 01 (to L.S.), two Stimulating and Advancing ACCM Research (StAAR) grants from the Department of Anesthesiology and Critical Care Medicine, JHU (to L.S. and J.S.), NHLBI grants R01HL073859 and R01HL126514 (to L.A.S) and a NHLBI K08 grant K08HL145132 (to J.S.). 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.

Reduced Cardiac Beta 1 Receptor Expression and Function in a Mouse Model of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disorder. HCMis characterized by cardiac hypertrophy, fibrosis, and an increased risk of fatalarrhythmias and sudden cardiac death. Previous studies in humans with HCM havedemonstrated increased cardiac norepinephrine spillover and reduced beta-1 receptor(B1R) expression in the left ventricle (LV). We have previously demonstrated thatcardiac sympathetic tone is elevated in an alpha-tropomyosin mutant mouse model ofHCM. We hypothesized that HCM mice would demonstrate reduced B1R expression inthe LV and attenuated heart rate (HR) and dP/dt max responses to ramped infusion of theB1R agonist, dobutamine. First, we utilized western blot to measure B1R proteinexpression in LV tissue from HCM and littermate wild-type (WT) mice (n=4 male micein each group). B1R expression was significantly reduced in the LV of HCM micecompared to WT littermate controls (HCM 60±1% vs. WT 100±4%; paired t-test, p<0.05). Next, we recorded left ventricular pressure in male and female HCM andlittermate WT control (n=5 male mice, each group; n=6 female mice, each group) miceanesthetized with isoflurane (2% in O2). Data were analyzed by 2-way ANOVA withgenotype and sex as factors. Baseline HR and dP/dt max were significantly lower inHCM compared to WT mice (genotype p<0.05), however, there were no sex differencesin either variable (sex p>0.05). Next, in order to assess cardiac B1R function, we firstinfused the ganglionic blocker chlorisondamine (6ug/g) to eliminate autonomic reflexfunction in HCM and littermate WT mice (n=4 mice, each group). Then, we performed adobutamine stress test via ramped infusion of dobutamine starting at 2ng/g/min andincreasing the dose in 2ng/g/min increments every 2 minutes up to 12ng/g/min via aprogrammable syringe pump. Data were analyzed by 2-way ANOVA with dose andgenotype as factors. Contrary to our hypothesis, ramped infusion of dobutamine resultedin a similar, significant (dose p<0.05) increase in HR in both HCM and WT mice(genotype p>0.05). Peak increases in HR occurred during the highest dose ofdobutamine (12ng/g/min; ΔHR HCM 58±19 vs. WT 70±20 beats/min) in both groups.Consistent with our hypothesis, increases in dP/dt max were significantly blunted inHCM mice compared to littermate WT controls (dose x genotype p<0.05). Peakincreases in dP/dt max occurred at a lower dose of dobutamine for HCM (4ng/g/min;ΔdP/dt max 1129±767 mmHg/s) compared to WT (8ng/g/min; ΔdP/dt max 4882±499mmHg/s). In summary, LV B1R expression is reduced in HCM mice. Increases in HR inresponse to ramped infusion of dobutamine were similar between HCM and WT micewhereas increases in dP/dt max were attenuated in HCM mice. We speculate that thedifferential inotropic and chronotropic responses to dobutamine could be due to regionaldifferences in B1R expression or contractile dysfunction in HCM mice. Michigan Technological University Startup. 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.

MORIN, A BIOFLAVONOID, ATTENUATES MYOCARDIAL ISCHEMIA-REPERFUSION INJURY BY ATTENUATING RISK/SAPK PATHWAY

Objective: It is important to address the impact of rising incidence of mortality and morbidity associated with myocardial infarction (MI). There is need to explore new safer and efficacious drugs with novel mechanisms to manage MI. Morin, (2-(2,4-Dihydroxyphenyl)-3, is a bioflavanoid which is found in Maclura cochinchinensis, Maclura tinctoria, Maclura pomifera and leaves of Psidium guajava. It possesses good anti-apoptotic, anti-inflammatory, and antioxidant activity. Hence, we have evaluated the cardio-protective effect of Morin in Myocardial Ischemia-Reperfusion (IR) injury model of rat. Design and method: Male albino Wistar rats were pre-treated with Morin (40 and 80 mg/kg; p.o.) for 28 days and on the 29th day, the chest cavity was opened and myocardial ishemia was induced for 45 minutes by ligatiing the LAD coronary artery. Thereafter, reperfusion was carried out for 60 minutes. The hemodynamic parameters as well as left ventricular pressures (±LV dp/dt and LVEDP) were recorded throughout the ischemia and reperfusion. At the end of the procedure, the blood and heart were collected for evaluation of cardiac-injury markers, antioxidant-oxidant parameters, inflammatory markets, histopathological evaluation and molecular signalling pathway protein expressions. Results: Morin pretreatment for 28 days at 40 mg/kg and 80 mg/kg doses significantly controlled hemodynamic parameters, reduced cardiac injury markers, inflammation and apoptosis and reduced oxidative stress and mitigated histological changes following IR injury in rat heart. Morin also downregulated expression of pro-inflammatory and pro-apoptotic SAPK pathway proteins (p38 and JNK), and upregulated the survival kinase protein expression i.e. RISK pathway (ERK, eNOS). Conclusions: Morin reduced myocardial oxidative stress, inflammation and apoptosis in ischemia-reperfusion induced cardiac injury through upregulation of RISK and downregulation of SAPK pathways proteins.

Macrophage to Myofibroblast Transition Promotes Hypertension-Induced Cardiac Diastolic Dysfunction

Cardiac diastolic dysfunction is a pathological continuum of hypertension eventually leading to heart failure—which is responsible for ~13% of all deaths in the United States. A hallmark of this disease is cardiac fibrotic remodeling, in which excessive extracellular matrix components are deposited into the myocardium. Recent studies have shown the novel ability of macrophages to differentiate into a fibrotic myofibroblast-like phenotype—termed macrophage to myofibroblast transition (MMT). This phenomenon has been implicated in renal fibrosis but, has not been investigated in the heart during hypertension or diastolic dysfunction. Therefore, we hypothesize that MMT plays a causal role in cardiac fibrotic remodeling in hypertension, promoting diastolic dysfunction. As such, we seek to investigate the prevalence of myofibroblast-transitioned macrophages in the heart, as well as determine the gravity of MMT-mediated fibrotic cardiac remodeling. To understand the pathological progression of hypertension to diastolic dysfunction, we utilized the classic DOCA + NaCl model of hypertension in C57BL/6 mice. This investigation is multi-pronged, in that, we seek to gauge diastolic function in vivo, as well as investigate the microenvironment of the heart in primary in vitro experiments. To achieve this, we employ echocardiography and direct left ventricular pressure and volume measurements to determine the progression of hypertension to diastolic dysfunction in the adult mouse heart. For primary in vitro analyses, mouse hearts were isolated and digested, and leukocytes were isolated by Percoll gradient. Cells were stained with α-SMA (myofibroblast) and CD68 (monocyte/macrophage). Finally, the deposition of fibrotic collagen was assessed by both Masson’s trichrome and picrosirius red tissue stains. Mice were subjected to DOCA + salt to induce hypertension. Ten days after this treatment, the left ventricular pressure change as a function of time was measured in the left ventricle. This analysis revealed degraded heart function, realized by a significant decrease in -dp/dt as soon as ten days following the onset of hypertension. Following, another cohort of hypertensive WT mouse hearts was isolated for staining. The results of these assays revealed increased cardiac fibrosis in the hearts of hypertensive mice—likely contributing to the deficit in cardiac function. Finally, in addition to this, flow cytometric analyses of isolated cardiac leukocytes revealed that hypertensive mice had a significant increase in the α-SMA+/CD68+ population of cells in the hypertensive mouse heart, implicating MMT in the rapid pathological progression of hypertension to diastolic dysfunction. These results characterize the presence of MMT cells in the hypertensive mouse heart. Furthermore, the increase of myofibroblast transition is accompanied by decreased cardiac diastolic function and enhanced fibrotic remodeling in the heart—alluding to the role of MMT in the pathological progression of hypertension to diastolic dysfunction. Future efforts into this phenomenon involve the real-time progression of hypertension to diastolic dysfunction via echocardiography, as well as a final, definitive measurement of diastolic function by PV loop. Finally, we will employ an angiotensin II model of hypertension to ensure that this phenomenon is encapsulated in other forms of hypertension, rather than just the DOCA + Salt model. We thank our sources of funding:NIG R01-HL146713, AHA 23TPA1076467. 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.

Long-term outcomes in patients with bicuspid valve stenosis and aortic dilation undergoing transcatheter valve implantation

BackgroundTo date, whether ascending aorta dilation (AAD) should be considered a contraindication for transcatheter aortic valve replacement (TAVR) remains a topic of debate.. ObjectiveThe study investigated the clinical outcome of TAVR in patients with bicuspid aortic valve stenosis (BAV-AS) complicated by AAD. MethodsWe included patients with BAV-AS who underwent TAVR between 2012 and 2019. We collected patient perioperative clinical data., tracked clinical outcomes for over four years post-TAVR, and obtained echocardiography images one year postoperatively. The Kaplan-Meier method was employed for analyzing both unadjusted and adjusted survival data, which was compared using the log-rank test. COX regression and nomograms were used to assess the impact of AAD on post-TAVR clinical outcomes in patients with aortic stenosis (AS), with all-cause mortality as the primary clinical endpoint. ResultsA total of 111 BAV patients were included in this study. Long-term follow-up showed an increased mortality risk in patients with BAV-AAD (adjusted Kaplan–Meier analysis: P = .02/0.001). Cox correlation analysis indicated that age (OR = 1.137; P = .034), AAD (OR = 3.51; P = .038), and postoperative left ventricular pressure (LVSP) (OR: 0.959; P = .044) were predictive factors for mortality more than four years after TAVR in patients with BAV. The area under the curve of the Nomogram predicting long-term survival for the training set of patients based on the above metrics was 0.845 (95% CI: 0.696–0.994). Short-term cardiac ultrasound follow-up showed a more rapid rate of AA expansion (0.29 [0–0.34] vs. -1 [−3.3–1] mm/month, P = .001) and a smaller proportion of AA diameter reduction (7.1% vs. 53.7%, P = .001) in patients who died. ConclusionsPatients with BAV-AAD-AS treated with TAVR have an increased risk of long-term mortality, and clinical prediction models, including AAD age and postoperative LVSP, may predict long-term patient survival. Condensed abstractThe study investigated the clinical outcome of transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic valve stenosis (BAV-AS) complicated by ascending aorta dilation (AAD). Patients with BAV-AAD-AS treated with TAVR have an increased risk of long-term mortality. AAD, age and postoperative LVSP, may predict long-term patient survival. Short-term cardiac ultrasound follow-up showed a more rapid rate of AA expansion and a smaller proportion of AA diameter reduction in patients who died. A high postoperative AAD expansion rate may indicate an adverse clinical outcome. Surgery regimens for tolerable BAV-AADs and can be considered as a treatment option.

Neutrophils orchestrate early cardiac remodeling after cardiac pressure overload

Cardiac pressure overload is a chronic condition where the left ventricle undergoes pathological hypertrophy and fibrosis ultimately causing heart failure. Increased myocardial stretch in left ventricular pressure overload initiates activation of an inflammatory and fibrotic response within resident cells leading to infiltration of immune cells. Neutrophils and monocytes are among the first responders during cardiac injury. While the role of monocytes and macrophages in pressure overload has been somewhat elucidated by multiple groups, including our lab, the role of neutrophils in chronic cardiac injury such as pressure overload is still unclear. We hypothesized that, like acute ischemic injury, neutrophils infiltrate to the heart early in pressure overload and initiate an inflammatory cascade which worsens cardiac dysfunction after TAC and that depletion of neutrophils in the first week of TAC would improve cardiac function. Our published single cell RNAseq dataset of immune cells (CD45+) cells from sham and TAC heart at day (D) 7 shows a distinct clustering of neutrophils with S100a9 (34-fold) , S100a8 (31-fold) , Retnlg (9-fold) , Il1b (5-fold) , and Slpi (5-fold) as top 5 differentially expressed genes (DEGs). Geneset enrichment analysis of top 58 DEGs (≥1.5-folds), shows significant association with pathways such as innate immune system, neutrophil degranulation, and signaling by interleukins by Reactome 2022 pathway. Using a murine model of transaortic constriction (TAC) to induce left ventricular pressure overload, we evaluated cardiac neutrophil counts by flow cytometry over the first week of TAC at D 2, 4 and 7. We observed that neutrophils (CD45+Ly6G+CD11b+) numbers consistently increase until D4, with a 7-fold increase at D2 to a 17-fold increase at D4 before returning to sham levels by D7. Using antibody (Anti Gr-1, 4 ug/g) mediated depletion of neutrophils, we observed that neutrophil depletion showed a protective effect in females compared to isotype controls with decreased cardiac hypertrophy and improved ejection fraction; while in male mice no change was observed between isotype and antibody treated groups. In conclusion, our data show that neutrophils peak early in pressure overload and orchestrate early cardiac remodeling with a potential for a sexually dimorphic role. We acknowledge funding from National Institute of Health under the awards numbers HL155993 and HL160665. 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.

Short-Chain Fatty Acid Butyrate Is an Inotropic Agent With Vasorelaxant and Cardioprotective Properties.

The heart can metabolize the microbiota-derived short-chain fatty acid butyrate. Butyrate may have beneficial effects in heart failure, but the underlying mechanisms are unknown. We tested the hypothesis that butyrate elevates cardiac output by mechanisms involving direct stimulation of cardiac contractility and vasorelaxation in rats. We examined the effects of butyrate on (1) invivo hemodynamics using parallel echocardiographic and invasive blood pressure measurements, (2) isolated perfused hearts in Langendorff systems under physiological conditions and after ischemia and reperfusion, and (3) isolated coronary arteries mounted in isometric wire myographs. We tested Na-butyrate added to injection solutions or physiological buffers and compared its effects with equimolar doses of NaCl. Butyrate at plasma concentrations of 0.56 mM increased cardiac output by 48.8±14.9%, stroke volume by 38.5±12.1%, and left ventricular ejection fraction by 39.6±6.2%, and lowered systemic vascular resistance by 33.5±6.4% without affecting blood pressure or heart rate invivo. In the range between 0.1 and 5 mM, butyrate increased left ventricular systolic pressure by up to 23.7±3.4% in isolated perfused hearts and by 9.4±2.9% following ischemia and reperfusion, while reducing myocardial infarct size by 81.7±16.9%. Butyrate relaxed isolated coronary septal arteries concentration dependently with an EC50=0.57 mM (95% CI, 0.23-1.44). We conclude that butyrate elevates cardiac output through mechanisms involving increased cardiac contractility and vasorelaxation. This effect of butyrate was not associated with adverse myocardial injury in damaged hearts exposed to ischemia and reperfusion.

Normothermic Ex Vivo Heart Perfusion With Exosomes From Human Umbilical Cord Mesenchymal Stem Cells Improves Graft Function in Donation After Circulatory Death Hearts.

This study aimed to investigate the cardioprotective effect of exosomes derived from human umbilical cord mesenchymal stem cells on donation after circulatory death (DCD) hearts preserved with normothermic ex vivo heart perfusion (EVHP) in a rat heart transplantation model. Thirty-two male Lewis rats were divided into 2 groups: the control group and the exosome group. The donor-heart rats were subjected to the DCD procedure by suffering a 15-min warm ischemia injury, subsequently preserved with EVHP for 90 min, and then transplanted into recipients via abdominal heterotopic heart transplantation. Vehicle or exosome was added into the perfusate of normothermic EVHP in the control or exosome group. We evaluated left ventricular graft function, myocardial inflammation, and myocardial apoptosis of the donor heart 1.5 h after heart transplantation. Furthermore, we investigate the alternation of myocardial gene expression in the donor hearts between both groups by transcriptome sequencing. The treatment with exosome significantly enhanced cardiac function through increasing left ventricular developed pressure, dp/dtmax, and dp/dtmin of DCD hearts at 90 min after heart transplantation compared with the control group. The myocardial cells in the exosome group exhibited an orderly arrangement without obvious edema. Furthermore, exosome added into perfusate in the exosome group significantly attenuated the level of inflammatory response and apoptosis. Transcriptome sequencing and RT-qPCR showed the phosphoinositide 3-kinase/protein kinase B pathway was activated after exosome treatment. Normothermic EVHP combined with exosome can be a promising and novel DCD heart preservation strategy, alleviating myocardial ischemia-reperfusion injury in the DCD heart.

PDZ-Binding Kinase, a Novel Regulator of Vascular Remodeling in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is high blood pressure in the lungs that originates from structural changes in small resistance arteries. A defining feature of PAH is the inappropriate remodeling of pulmonary arteries (PA) leading to right ventricle failure and death. Although treatment of PAH has improved, the long-term prognosis for patients remains poor, and more effective targets are needed. Gene expression was analyzed by microarray, RNA sequencing, quantitative polymerase chain reaction, Western blotting, and immunostaining of lung and isolated PA in multiple mouse and rat models of pulmonary hypertension (PH) and human PAH. PH was assessed by digital ultrasound, hemodynamic measurements, and morphometry. Microarray analysis of the transcriptome of hypertensive rat PA identified a novel candidate, PBK (PDZ-binding kinase), that was upregulated in multiple models and species including humans. PBK is a serine/threonine kinase with important roles in cell proliferation that is minimally expressed in normal tissues but significantly increased in highly proliferative tissues. PBK was robustly upregulated in the medial layer of PA, where it overlaps with markers of smooth muscle cells. Gain-of-function approaches show that active forms of PBK increase PA smooth muscle cell proliferation, whereas silencing PBK, dominant negative PBK, and pharmacological inhibitors of PBK all reduce proliferation. Pharmacological inhibitors of PBK were effective in PH reversal strategies in both mouse and rat models, providing translational significance. In a complementary genetic approach, PBK was knocked out in rats using CRISPR/Cas9 editing, and loss of PBK prevented the development of PH. We found that PBK bound to PRC1 (protein regulator of cytokinesis 1) in PA smooth muscle cells and that multiple genes involved in cytokinesis were upregulated in experimental models of PH and human PAH. Active PBK increased PRC1 phosphorylation and supported cytokinesis in PA smooth muscle cells, whereas silencing or dominant negative PBK reduced cytokinesis and the number of cells in the G2/M phase of the cell cycle. PBK is a newly described target for PAH that is upregulated in proliferating PA smooth muscle cells, where it contributes to proliferation through changes in cytokinesis and cell cycle dynamics to promote medial thickening, fibrosis, increased PA resistance, elevated right ventricular systolic pressure, right ventricular remodeling, and PH.

Clinical Features and Multimodality Diagnostic Tools of Pulmonary Hypertension

Pulmonary hypertension (PH) is defined as an increase in mean pulmonary arterial pressure (mPAP) above normal (> 20 mmHg) and an increase in pulmonary vascular resistance (pulmonary vascular resistance / PVR) above normal in resting settings. The pathophysiology of PH involves remodeling of the pulmonary vessels, from the main pulmonary arteries, lobar arteries, segmental arteries, distal arteries, pulmonary arterioles, capillaries to the postcapillary pulmonary veins. In general, the epidemiological figures for PH are not known with certainty. The United Kingdom reported a PH prevalence of 97 cases per one million people, with a female-to-male ratio of 1.8. The diagnostic strategy for PH focuses primarily on two issues. The primary objective is to improve the early detection of PH and expedite the transfer of patients at high risk for PAH, CTEPH, or other forms of severe PH to a PH center. The second objective is to identify the underlying disease, including left heart disease (Group 2 PH) and lung disease (Group 3 PH), as well as comorbidities, in order to assure proper classification, risk assessment, and therapy. The gold standard for detecting and categorizing pulmonary hypertension is right heart catheterization (RHC). Clinical scoring in the form of shortness of breath without any obvious cause accompanied by physical examination, ECG and Thorax X-ray images which depict an enlarged right heart have good specificity and sensitivity for the diagnosis of pulmonary hypertension in patients with congenital heart disease. A high right ventricular pressure, mean PAP, and BNP values during observation, as well as heart size on chest X-ray can be predictors of a poorer prognosis in this population. Keyword: Clinical Risk Scoring, Pulmonary Hypertension, Right Heart Catheterization.

The American Association for Thoracic Surgery (AATS) 2024 expert consensus document: Management of neonates and infants with Ebstein anomaly

ObjectivesSymptomatic neonates and infants with Ebstein anomaly (EA) require complex management. A group of experts was commissioned by the American Association for Thoracic Surgery to provide a framework on this topic focusing on risk stratification and management. MethodsThe EA Clinical Congenital Practice Standards Committee is a multinational and multidisciplinary group of surgeons and cardiologists with expertise in EA. A citation search in PubMed, Embase, Scopus, and Web of Science was performed using key words related to EA. The search was restricted to the English language and the year 2000 or later and yielded 455 results, of which 71 were related to neonates and infants. Expert consensus statements with class of recommendation and level of evidence were developed using a modified Delphi method, requiring 80% of members votes with at least 75% agreement on each statement. ResultsWhen evaluating fetuses with EA, those with severe cardiomegaly, retrograde or bidirectional shunt at the ductal level, pulmonary valve atresia, circular shunt, left ventricular dysfunction, or fetal hydrops should be considered high risk for intrauterine demise and postnatal morbidity and mortality. Neonates with EA and severe cardiomegaly, prematurity (<32 weeks), intrauterine growth restriction, pulmonary valve atresia, circular shunt, left ventricular dysfunction, or cardiogenic shock should be considered high risk for morbidity and mortality. Hemodynamically unstable neonates with a circular shunt should have emergent interruption of the circular shunt. Neonates in refractory cardiogenic shock may be palliated with the Starnes procedure. Children may be assessed for later biventricular repair after the Starnes procedure. Neonates without high-risk features of EA may be monitored for spontaneous closure of the patent ductus arteriosus (PDA). Hemodynamically stable neonates with significant pulmonary regurgitation at risk for circular shunt with normal right ventricular systolic pressure should have an attempt at medical closure of the PDA. A medical trial of PDA closure in neonates with functional pulmonary atresia and normal right ventricular systolic pressure (>20-25 mm Hg) should be performed. Neonates who are hemodynamically stable without pulmonary regurgitation but inadequate antegrade pulmonary blood flow may be considered for a PDA stent or systemic to pulmonary artery shunt. ConclusionsRisk stratification is essential in neonates and infants with EA. Palliative comfort care may be reasonable in neonates with associated risk factors that may include prematurity, genetic syndromes, other major medical comorbidities, ventricular dysfunction, or sepsis. Neonates who are unstable with a circular shunt should have emergent interruption of the circular shunt. Neonates who are unstable are most commonly palliated with the Starnes procedure. Neonates who are stable should undergo ductal closure. Neonates who are stable with inadequate pulmonary flow may have ductal stenting or a systemic-to-pulmonary artery shunt. Subsequent procedures after Starnes palliation include either single-ventricle palliation or biventricular repair strategies.

Patient-specific closed-loop model of the fontan circulation: Calibration and validation

The Fontan circulation, designed for managing patients with a single functional ventricle, presents challenges in long-term outcomes. Computational methods offer potential solutions, yet their application in cardiology practice remains largely unexplored. Our aim was to assess the ability of a patient-specific, closed-loop, reduced-order blood flow model to simulate pulsatile blood flow in the Fontan circulation. Using one-dimensional models, we simulated the aorta, superior and inferior venae cavae, and right and left pulmonary arteries, while lumping heart chambers and remaining vessels into zero-dimensional models. The model was calibrated with patient-specific haemodynamic data from combined cardiac catheterisation and magnetic resonance exams, using a novel physics-based stepwise methodology involving simpler open-loop models. Testing on a 10-year-old, anesthetised patient, demonstrated the model's capability to replicate pulsatile pressure and flow in the larger vessels and ventricular pressure. Average relative errors in mean pressure and flow were 2.9 % and 3.6 %, with average relative point-to-point errors (RPPE) in pressure and flow at 5.2 % and 16.0 %. Comparing simulation results to measurements, mean aortic pressure and flow values were 50.7 vs. 50.4 mmHg and 41.6 vs. 41.9 ml/s, respectively, while ventricular pressure values were 28.7 vs. 27.4 mmHg. The model accurately described time-varying ventricular volume with a RPPE of 2.9 %, with mean, minimum, and maximum ventricular volume values for simulation results vs. measurements at 59.2 vs. 58.2 ml, 38.0 vs. 37.6 ml, and 76.0 vs. 74.4 ml, respectively. It provided physiologically realistic predictions of haemodynamic changes from pulmonary vasodilation and atrial fenestration opening. The new model and calibration methodology are freely available, offering a platform to virtually investigate the Fontan circulation's response to clinical interventions and explore potential mechanisms of Fontan failure. Future efforts will concentrate on broadening the model's applicability to a wider range of patient populations and clinical scenarios, as well as testing its effectiveness.

Disproportionately high aortic valve calcium scores in atrial fibrillation: implications for transcatheter aortic valve replacement.

Doppler mean gradient (MG) can underestimate aortic stenosis (AS) severity in patients with atrial fibrillation (AF) compared with patients with sinus rhythm (SR), potentially delaying intervention in AF. This study compared outcomes in patients with AF and SR following transcatheter aortic valve replacement (TAVR) and investigated delay in TAVR based on computed tomography aortic valve calcium score (AVCS). Patients who underwent TAVR from 2013 to 2017 for native valve severe AS were identified from an institutional database. Baseline characteristics and overall survival were compared between those with SR and AF. There were 820 patients (mean age 81 years; 41.6% females) included in this study. AF was present in 356 patients. Patients with AF were older (82.2 vs. 80.5, P = 0.003) and had a lower MG compared with patients with SR (42.0 vs. 44.9, P = 0.002) with similar indexed aortic valve area (0.4 vs. 0.4, P = 0.17). Median AVCS was higher in AF (males: AF 2850.0 vs. SR 2561.0, P = 0.044; females: AF 1942.0 vs. SR 1610.5, P = 0.025). Projected AVCS, assuming the same age of diagnosis, was similar between AF and SR. Median survival post-TAVR was worse in AF compared with SR (3.2 vs. 5.4 years, log rank P < 0.001). AF, lower MG, higher right ventricular systolic pressure, dialysis, diabetes, and significant tricuspid regurgitation were associated with higher mortality (P < 0.05 for all). Older age and higher AVCS in patients with AF compared with those with SR suggest that AS was both underestimated and more advanced at TAVR referral.