bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 373: A Novel Haplotype In The G(alpha)s Gene Alters Gene Expression And Responsiveness To Receptor Stimulation And Predicts Cardiac Performance In Humans
Authors: Frey Ulrich H , Leineweber Kirsten , Adamzik Michael , Kottenberg-Assenmacher Eva , Jakob Heinz , Siffert Winfried , Peters Juergen
Published: July 2021

Background: Transgenic mice with cardiac Gαs overexpression exhibit enhanced inotropic and chronotropic responses to sympathetic stimulation, but develop cardiomyopathy with age. In contrast, chronic beta-adrenergic receptor blockade (beta-AR) mitigates cardiac dilation and depressed left ventricular function in these models. We tested the hypothesis that naturally occurring variants in regulatory regions of the human gene GNAS encoding Gαs result in altered Gαs expression and signal transduction properties in humans.

Methods and results: Sequencing the promoter and intron 1 of GNAS revealed 11 single nucleotide polymorphisms resulting in three common haplotypes. In reporter assays haplotype *3 constructs exhibited significantly higher promoter activity compared to haplotype *1 and *2 constructs. In hearts from 54 patients under chronic beta-AR blockade scheduled for coronary artery bypass grafting (CABG) Gαs mRNA expression was more than 50% higher in homozygous *3 carriers (*3/*3) than in heterozygous (*3/−) and negative *3 (−/−) carriers (Gαs/Actin, 0.16±0.06 vs. 0.10±0.03 vs. 0.09±0.04; p=0.002). Consistent with increased Gαs expression, functional studies showed that *3/*3 carriers had higher basal activities of adenylyl cyclase (AC, 32.4±12.9 vs. 29.1±7.9 vs. 25.5±5.3 pmol/min/mg; p=0.019) and maximal isoproterenol-stimulated activities were markedly higher for the *3/*3 compared to *3/− and −/− carriers (79.3±29.7 vs. 66.7±16.2 vs. 57.3±11.1 pmol/min/mg; p=0.002). Direct AC stimulation with Forskolin was unaffected by GNAS haplotypes. Hemodynamic measurements in 137 bypass patients under chronic beta-AR blockade revealed a higher cardiac index (2.2±0.2 vs. 1.9±0.1 vs. 1.8±0.1 l min-1 m-2; p=0.025) in *3/*3 carriers. This was also in line with a lower NYHA functional class (1.8±0.2 vs. 2.2±0.1 vs. 2.3±0.1; p=0.040) and NT-proBNP levels (339±87 vs. 746±110 vs. 1365±259 pg/ml; p=0.002).

Summary: Increased Gαs expression due to a functional haplotype results in altered signal transduction properties and may have salutary effects on cardiac performance in CABG patients under chronic beta-AR blockade. Our data therefore could help to translate results from transgenic mice to genotype-phenotype correlations in humans.
Abstract 2626: Intramyocardial High-Energy Phosphate Depletion during Ventricular Fibrillation Correlates with Electrocardiographic Change
Authors: Salcido David D , Menegazzi James J , Logue Eric S , Suffoletto Brian P , Sherman Lawrence D
Published: July 2021

Background: Ventricular fibrillation (VF) is highly energy-wasteful, producing no perfusion. High-energy phosphates (HEPs) deplete rapidly during VF, adding to metabolic/ischemic stress and adversely affecting VF. We have shown that the scaling exponent (ScE) of the VF waveform predicts rescue shock outcome and can be used to guide decision-making during CPR.

Hypotheses: We hypothesized that intramyocardial HEPs would rapidly diminish during untreated VF, and that this decrease would correlate with changes in the ScE.

Methods: We anesthetized and instrumented 18 domestic swine (26.6 ± 1.9 kgs). We systematically assigned them (6 per group) to 5, 10, or 15 minutes of untreated VF, which was induced with a transthoracic shock. At the predetermined timepoint open-chest biopsies were taken from the left ventricle. Biopsied tissue samples were immediately flash frozen in a slurry of dry ice and isopentane (-90
o
C), and HEPs were extracted with 1% trichloroacetic acid. Levels of ATP and ADP were measured luminometrically with an ADP/ATP ratio kit. ATP and ADP levels were assayed in duplicate, and the average recorded (reported in nmol/mg myocardial tissue). Fifteen seconds of ECG signal was digitally recorded (for ScE analysis) immediately prior to biopsy. ScE values were paired with ATP and ADP for calculation of linear regression. HEPs vs. time were compared with ANOVA.

Results: Mean ATP/ADP were 1.20/0.21 at 5 min, 0.94/0.12 at 10 min, and 0.45/0.11 at 15 min. ATP correlated with ScE (r=.63, p=0.009) but ADP did not (r=.35, p=0.17). Both ATP (p=0.004) and ADP (p=0.024) differed over time.

Conclusions: HEPs rapidly diminish during untreated VF. ATP depletion correlates with ScE change.
Abstract 2629: High Dose Erythropoietin Improves the Postresuscitation Myocardial Dysfunction and Survival in an Appropriate Therapeutic Time Window
Authors: Huang Chien-Hua , Hsu Chiung-Yuan , Chen Huei-Wen , Chang Wei-Tien , Chen Wen-Jone
Published: July 2021

Introduction:
The myocardial dysfunction carries high mortality rate in the postresuscitation period. Interventions for improving myocardial dysfunction may improve the outcomes of resuscitated victims. The erythropoietin (EPO) provides protective effects for the myocardium with ischemia-reperfusion injuries. However, its effects on the treatment of cardiopulmonary arrest and post-resuscitation myocardial dysfunction remain unknown.

Hypothesis:
EPO can improve the postresuscitation myocardial dysfunction in an appropriate therapeutic time window.

Methods:
Asphyxia-induced cardiac arrest was performed in male adult Wistar rats. Cardiopulmonary resuscitation including chest compressions, mechanical ventilation and epinephrine (0.01 mg/kg) was begun after 6.5 or 9.5 minutes of asphyxia. Animals were randomized to undergo treatment with intravenous EPO (5000 U/kg) or equivalent volume of 0.9% saline placebo. These agents were administrated 3 minutes after the return of spontaneous circulation.

Results:
The better left ventricular dP/dt
40
(2958±827 vs. 1321±1200 mmHg/s, P<0.05) and maximal -dP/dt (2562±546 vs. 745±877 mmHg/s, P<0.05) at 120 minutes after cardiac arrest, and better left ventricular fraction shortening (32.0 ± 2.0 vs. 24 ± 6.7 %, P<0.05) by echocardiography at 90 minutes after cardiac arrest were noted in the EPO-treated group compared to the control group in the condition of 6.5 minutes of asphyxia. The EPO treated group had better neurological recovery at 24 hours after resuscitation. Survival rate at 72 hours after 6.5 minutes of asphyxia was better in the EPO-treated group (50% vs. 20 %, P=0.02). No animal survived 72 hours after 9.5 minutes of asphyxia either in EPO-treated or control group. More activation of cardiac Akt and ERK 42/44 signaling pathways were noted in the EPO-treated group than the control group.

Conclusions:
EPO has the potential to improve postresuscitation myocardial dysfunction and short term survival in rats after asphyxia-induced cardiac arrest in an appropriate therapeutic time window.
Abstract 2630: Evidence of Early Heart Mitochondrial Dysfunction after Resuscitation from Cardiac Arrest
Authors: Riobo Natalia A , Han Fei , Da Tong , Becker Lance B
Published: July 2021

Background:
Reperfusion injury post-resuscitation is associated with metabolic dysfunction and free radicals production. It has been hypothesized that mitochondrial permeability changes induced by calcium overload underlies this uncoupling of respiration from ATP synthesis and initiates cytochrome c-dependent apoptotic cascades. Our goal is to evaluate the intrinsic status of the mitochondrial electron transfer chain, i.e. irreversible modifications, in resuscitated animals independently of transient changes in calcium and permeability.

Methods:
Female mice were subjected to 8 min cardiac arrest by KCl injection followed by mechanical ventilation and CPR until return of spontaneous circulation (resuscitation rate: 86%, 24 h survival: 40%) under continuous blood pressure and temperature monitoring. Animals were divided in 4 groups: SHAM (instrumented, no cardiac arrest), CA (8 min cardiac arrest), R30 (30 min post-resuscitation), and R60 (60 min post-resuscitation). Heart mitochondria were immediately isolated and physically disrupted to dissipate ionic gradients in the presence of a calcium chelator. Production of hydrogen peroxide (H
2
O
2
) by Complex I and III was determined fluorometrically with the Amplex Red-HRP system and the activities of Complex I, II, and the Complex I-III and II-III segments by spectrophotometric techniques using appropriate substrates and inhibitors. Cytochrome c content and the COX IV subunit (as a loading control) were analyzed by western blot and densitometry.

Results:
A 40% increase in H
2
O
2
production by Complex I and III was evident after just 8 min of cardiac arrest (ECA group, p<0.05), which was followed by a progressive reduction in Complex I activity (ECA>R30>R60), resulting in a relative doubling of electron leak. In contrast, Complex II and II-III activities and cytochrome c content remained unaffected at all times evaluated.

Conclusions:
Using an animal model that closely mimics resuscitation in humans, we have found signs of early mitochondrial dysfunction independently of transient changes in permeability and calcium. These changes are consistent with increased ROS production at expense of impaired oxidative phosphorylation.
Abstract 2631: Reactive Oxygen Species (ROS) Generation and Recovery Of Myocardial Function After Low Flow Reperfusion In The Whole Heart
Authors: Aune Sverre E , Clanton Thomas L , Angelos Mark G
Published: July 2021

We hypothesize that some levels of CPR generated low-flow may in fact worsen myocardial recovery compared with no-flow of similar duration. To test this hypothesis we determined the effect of low-flow reperfusion simulating CPR, on myocardial ROS production, cellular redox changes and recovery of contractile function in the whole heart.

Methods:
Isolated perfused male Sprague Dawley rat hearts were subjected to either 20 minutes of global ischemia followed by full reperfusion with 85 mm Hg perfusion (Control) or 3 minutes of global ischemia followed by 17 minutes of low-flow with perfusion pressure of 20 mm Hg before full reperfusion at 20 minutes (CPR model). Full reperfusion was for 30 minutes in all hearts. A fiberoptic spectrometer measured fluorescence on the left ventricular wall. Hearts were preloaded with 2 probes, dihydrofluorescein (an intracellular probe) and amplex red (an extracellular probe), both of which are oxidized and fluoresce in the presence of reactive oxygen species (ROS). NADH autofluorescence, a measure of cellular redox state, and LV contractile function were continuously measured. Changes in fluorescence and function were normalized to baseline and compared between groups using ANOVA.

Results:
At the end of the 30 minute reperfusion period, rate pressure product (RPP in mmHg/min) was significantly reduced in CPR modeled hearts (RPP = 6,733 ± 3,720) (p<0.01) as compared to Control (RPP = 17,000 ± 1,873). CPR type low-flow resulted in a significant decrease in [NADH] compared with control (p<0.05). In CPR modeled hearts, a reduction in the intracellular ROS burst (fluorescein signal), but an increase in the extracellular ROS burst (amplex red signal) was seen at the onset of full reperfusion (20 minutes) compared with Control (p<0.01).

Conclusions:
It is well understood that under CPR conditions, the level of low-flow can be quite variable. However, at some level of low-flow, recovery of myocardial function may be worse than recovery following a similar duration of no-flow. This depressed myocardial function may be ROS mediated, as this level of low-flow alters the compartmentalizded ROS burst seen at full reperfusion.
Abstract 2652: Primary Angioplasty And Thrombolysis For ST Elevation Myocardial Infarction Result In Similar Left Ventricular Function And Rates Of Inducible Ventricular Tachycardia.
Authors: Chong James J , Gannesan Anand N , Eipper Vickie , Kovoor Pramesh
Published: July 2021

Introduction/Hypothesis.

Electrophysiological studies (EPS) predict risk of sudden death after myocardial infarction. Primary angioplasty has become the preferred method of treatment for STEMI due to improved patency rates of the infarct related artery, along with decreased rates of reinfarction and death. Despite this, intravenous thrombolysis remains the first line treatment in 30 –70% of cases worldwide. We assessed the hypothesis that the left ventricular ejection fraction (LVEF) and rates of inducible VT would be more favorable in patients treated with primary angioplasty compared to thrombolysis.

Methods/Results.

Consecutive patients receiving primary angioplasty (n=225) or thrombolysis (n=195) for STEMI were included. Mean LVEF assessed predominantly by gated blood heart pool scan was 47.7 ±12.1% for the primary angioplasty group and 46.3 ±13.0% for the thrombolysis group (p=0.30). The proportion of patients with LVEF less than 40% was 29.7% in the primary angioplasty group and 29.6% in the thrombolysis group (p=0.98). Patients with LVEF less than 40% underwent EPS. VT was inducible in 10% of patients who had primary angioplasty versus 11% of patients who had thrombolysis (p=0.69). Mean cycle length (CL) of inducible VT in milliseconds (ms) was 246 ± 48 for the angioplasty group and 261 ± 62 for thrombolysis group (p=0.65). Implantable cardiac defibrillators were inserted in 30 patients of which 8 (27%) had appropriate device activations. The mean time from infarction to first spontaneous activation was 387 ± 458 days. Mean CL of spontaneous VT was 314 ± 62 ms.

Conclusions.

In conclusion patients treated with thrombolysis or primary angioplasty for STEMI are likely to have similar resultant left ventricular function and rates of inducible ventricular tachycardia. There was a surprisingly high rate of spontaneous defibrillator activations often occurring late after myocardial infarction.

Table 1:

Patient and treatment characteristics for each group.
Abstract 2670: Time to Granulocyte-Colony Stimulating Factor Treatment after Acute Myocardial Infarction Does Not Affect Left Ventricular Recovery: Results from the STEMMI Trial
Authors: Ripa Rasmus S , Yongzhong Wang , Jørgensen Erik , Kastrup Jens
Published: July 2021

Introduction:
Granulocyte-colony stimulating factor (G-CSF) therapy after a STEMI does not affect left ventricular systolic function when compared to placebo. However, recent human and animal studies suggest that the timing of G-CSF therapy is crucial.

Hypothesis:
G-CSF improves recovery of left ventricular ejection fraction if administered very early after a STEMI.

Methods:
The STEMMI trial MRI-subpopulation was analyzed. The trial included 58 patients (47 men; 56 [SD 9] years) with STEMI treated with primary PCI <12 hours after symptom onset. Patients were randomized to double blind treatment with G-CSF (10 μg/kg/day) or placebo for 6 days. Treatment with G-CSF (time to G-CSF) was initiated 30 hours (range 17 – 65) after PCI. Left ventricular function was evaluated with cardiac MRI and analyzed by an independent blinded core laboratory.

Results:
Circulating CD34+ cells increased during G-CSF therapy. However, there was no correlation between time to G-CSF and maximum plasma concentration of CD34+ cells (r=-0.3, p=0.2). Baseline ejection fraction was independent of time to G-CSF. The recovery of ejection fraction from baseline to 6 months was not associated with time to G-CSF (regression coefficient 0.2/hour, 95% CI -0.2 to 0.5), an identical improvement was found in the placebo group (p=0.8). There was no association between plasma concentrations of CD34+ cells and improvement in left ventricular function.

Conclusions:
We found no indication that early initiation of treatment with G-CSF improves recovery of left ventricular ejection fraction as compared to both late G-CSF and placebo. It remains to be determined if treatment initiation <17 hours after PCI improves recovery.
Abstract 2677: Reduction In
Tie-2+/flk-1+
Vascular Stem Cells In Thoracic Aortic Aneurysm With Dissections: A Novel Contributor To Acellular Lesion Development
Authors: Geng Yong-Jian , Guo Dongchun , Milewicz Dianna M , Buja L. Maximillian , Wang Jinjie , Ge Shuping
Published: July 2021

Background.
Ascending thoracic aortic aneurysms leading to type A dissections (TAAD) are a life-threatening disease triggered by a complex interactions between environmental and genetic factors. Pathologically, this disease is characterized by a progressive loss of vascular smooth muscle cells (SMCs) and extracellular elastic fibers in the aortic media. Apoptosis, a form of programmed cell death, has been shown to contribute to the loss of medial SMCs. However, little is known about the role of vascular progenitor or stem cells in the pathogenesis of aortic aneurysms.

Methods and Results.
In this study we examined expression of Tie-2 (receptor for angiopoietin) and Flk-1 (receptor for vascular endothelial cell growth factor), two receptors critical for regulation of vascular stem cell survival and growth in the aortic lesions of patients with TAAD. Immunohistochemistry with specific antibodies against Tie-2 and Flk-1 showed a marked reduction in the numbers of Tie+/Flk+ cells in TAAD when compared to control aortas. There was also a change in the distribution pattern of vascular progenitor cells positive for both Tie-2 and Flk-1 in TAAD patients’ aortic tissues. Compared to normal control aortas, the Tie-2 and Flk-1 immunostained cells were much lower in intensity and scattered. In the regions with paucity of Tie-2+/Flk-1+ cells, there was an increased number of apoptotic cells as determined by in situ DNA end-labeling (TUNEL). Many of the Tie-2 and Flk-1 positive cells in TAAD showed poor morphology with nuclear degeneration and cytoplasmic fragmentation and disarray.

Conclusion
. These results indicate a paucity of Tie-2+/Flk-1+ vascular stem cells in the aortic wall of patients with TAAD, implying that the stem cell capacity to regenerate SMCs is exhausted. Similar loss of stem cells is observed with Duchenne muscular dystrophy, where the regenerated capacity is significantly compromised. Stem cells loss may similarly impair the capacity of SMCs in aortic tissue in repair and regeneration, and ultimately lead to TAAD formation.
Abstract 2687: Arterial Stiffness Determines Baseline Coronary Flow And Flow Reserve In Untreated Patients With Arterial Hypertension
Authors: Ikonomidis Ignatios , Lekakis John , Triantafyllidi Helen , Papadopoulos Costas , Georgoula Georgia , Paraskevaidis Ioannis , Kremastinos Dimitrios T
Published: July 2021

Arterial stiffness is a marker of subclinical atherosclerosis with prognostic significance. Coronary microcirculation is disturbed in patients with arterial hypertension. We investigated whether the arterial stiffness may determine baseline coronary flow and flow reserve (CFR) in never-treated hypertensives.

METHODS: We studied 100 untreated consecutive patients (mean age: 55±11 years 53 male and 47 females), with newly diagnosed arterial hypertension and 20 controls matched for sex, age and atherosclerotic factors, Exclusion criteria were history of diabetes, familiar hyperlipidemia, CAD, cardiomyopathy and chronic obstructive pulmonary disease. We measured a) Carotid to femoral artery pulse wave velocity (PWV) as an estimate of arterial stiffness using the Complior apparatus b) Peak Systolic (Vs) and diastolic (Vd) coronary blood flow velocity , Vd/Vs ratio, Deceleration Time (DT-Vd) and time integral (VTI-Vd) of Vd using a 7MHZ transducer by means of colour-guided Doppler echocardiography at the distal tract of the LAD c) Ratio of VTI-Vd after adenosine infusion (140μg/kg/min) to VTI-Vd at baseline to assess coronary flow reserve (CFR)

RESULTS: All patients had normal LVmass (men<134gr/m2, women <110gr/m2) and had higher PWV (10.4±1.7 vs. 8.2±1.4 m/s, p<0.001) and lower CFR, Vd/Vs and DT-Vd (2.6±0.6 vs 3.4±0.7, p<0.001, 1.78±0.31 vs. 1.97±0.38, p=0.04 and 973±226 vs. 1113±332 ms, p<0.001 respectively) than controls. Increasing PWV was related to decreasing Vd/Vs (r=-0.65, p<0.001) , DT-Vd (r=-0.8, p<0.001), CFR (r=-0.7, p<0.001) and VTI-Vd post adenosine (r=-0.24, p=0.034). In multivariate regression analysis, PWV and smoking were the most important determinants of CFR among age, sex, body mass index, mean blood pressure and hyperlipidemia (b: - 2.21, p<0.001 and b: - 2.68, p=0.032 respectively). Patients with CFR>2 had significantly lower PWV, than those with CFR<2 (n=20) (10±1.5 vs. 12±2 m/s p<0.001). By ROC analysis, a PWV>10.7 m/sec predicted a CFR < 2 with a 84% and 80% sensitivity and specificity respectively.

CONCLUSIONS: Arterial stiffness determines with baseline coronary flow and flow reserve in never treated hypertensives with no evidence of LV hypertrophy.
Abstract 2688: Can Stress Echocardiography With Tissue Characterization Evaluate Noncritical Coronary Stenosis? A Validation Study Against Simultaneous Measurement of Fractional Flow Reserve
Authors: Poerner Tudor , Vilardi Sisi , Goebel Björn , Figulla Hans R , Süselbeck Tim
Published: July 2021

Aim of this study
was to evaluate the ability of different echocardiographic modalities to detect myocardial ischemia due to non-critical coronary stenosis, compared to the fractional flow reserve (FFR) as gold standard.

Material and Methods:
We investigated 22 consecutive patients presenting with stable angina, negative exercise tests and coronary 1-vessel disease with 50–75% diameter stenosis. TDE/SRI was performed at baseline and at peak hyperemia during 0.14 mg/kg/min adenosine infusion simultaneously with intracoronary FFR measurements. Angioplasty was carried out if FFR < 0.75, repeating TDE/SRI during first balloon inflation. Visual wall motion score, peak systolic values for myocardial velocity (Vs), strain rate (SRs), strain (Ss) and peak overall strain (Smax) were determined in the region of interest. Postsystolic shortening (PSS), accepted as typical marker of acute myocardial ischemia, was defined as (Smax-Ss)/Smax > 0.3, with reduced Ss < 15%.

Results:
Pathologic FFR < 0.75 was found in 11 patients (Table 1

), who underwent angioplasty. Myocardial contractility reflected by SRs increased during hyperemia only in the patient group with FFR > 0.75 and decreased markedly during balloon inflation. Hyperemic SRs variation correlated with FFR (r = 0.5, p = 0.018) and predicted significantly pathologic FFR with an area under ROC curve of 0.86 (p <0.01). PSS was identified in 10 of 11 patients during vessel occlusion, but had a low sensitivity (2 of 11 patients with FFR < 0.75) for the more subtle changes during hyperemia.

Conclusion:
Functional assessment of moderate-to-severe coronary stenosis remains a diagnostic challenge. PSS occurrence cannot serve as a reliable noninvasive alternative to FFR. However, the blunted hyperemic variation of systolic strain rate was able to predict a pathologic FFR, even in this small group of patients. Therefore, TDE/SRI emerges as a promising tool to enhance the diagnostic accuracy of adenosine stress echocardiography.

Table 1
Abstract 2702: Changes in Filling Pressures Rather than in Daily Weights Predict Heart Failure Events with Active Heart Failure Disease Management
Authors: Renlund Dale G , Aaron Mark F , Magalski Anthony , Cho Yong K , Jessup Mariell , Bourge Robert C , Zile Michael R , Stevenson Lynne W
Published: July 2021

Introduction
: While active heart failure (HF) disease management (HFM) that includes frequent patient contact and education about symptoms, daily weights, and medication adjustment has been shown to decrease HF events, recurrent HF hospitalization for fluid overload remains frequent. To determine whether HF events that occur despite HFM can still be predicted from changes in serial weights and filling pressures, HF events were analyzed from the COMPASS-HF trial.

Methods and Results
: After a recent HF hospitalization and COMPASS-HF study enrollment at 28 experienced HF centers, 274 patients received HF education and averaged 24.7 staff contacts/6 months. HF event rates decreased from 1.9 in the 6 months prior to enrollment to 0.85 and 0.67 during 6 months after enrollment in the study (control and treatment arms, respectively). For 66 HF events, home weights and invasively measured right ventricular diastolic pressures (RVDP) transmitted from home were available from 7 weeks previously and were defined as baseline. RVDP rose steadily from 4 weeks to 1 day prior to the HF event, while weights varied without major increase until 1 day prior (figure

). RVDP increased by ≥ 2 mm Hg at least 1 week prior to 39/66 events (59%), while weight gain increased by ≥ 2 pounds at least 1 week prior to 19/66 events (29%).

Conclusions
: Events occurring despite HFM, which includes diuretic adjustment for symptoms and weight gain, were predicted by increasing cardiac filling pressures but not by weight gain. In addition to changes in daily weights, increases in filling pressures may guide interventions to avert HF events otherwise not anticipated from routine weights and frequent HFM contact.
Abstract 143: Caveolae Regulate PI3K/Akt/RhoA-Mediated p38 MAPK Nuclear Translocation in Leptin-Induced Cardiomyocyte Hypertrophy
Authors: Zeidan Asad , Javadov Sabzali , Chakrabarti Subrata , Karmazyn Morris
Published: July 2021

Background
: Obesity is associated with increased leptin production which may contribute to cardiac hypertrophy. However, the mechanism of leptin-induced cardiac hypertrophy remains incompletely understood. Previous studies have shown that the RhoA/ROCK/cofilin pathway and p38 MAPK but not ERK1/2 activation are major contributors to leptin-induced cardiac hypertrophy. In this study we explored the roles of caveolae and the PI3K/Akt pathway in regulating RhoA and p38 MAPK activation during leptin-induced cardiomyocyte hypertrophy.

Methods and Results
: Neonatal rat ventricular myocytes were cultured with 3.1 nmol/L leptin for 24 hours. Caveolae number and expression of caveolin-3 were significantly increased after leptin treatment (2 and 3 fold, respectively; p<0.01). These effects were associated with a 29% (p<0.05) increase in cell surface area and a 40% (p<0.05) increase in leucine incorporation, indicating cardiomyocyte hypertrophy. Disruption of cardiomyocyte caveolae with 5 mM methyl-beta-cyclodextrin (MβCD) significantly inhibited leptin-induced hypertrophy. RhoA was detected in caveolae fractions of a sucrose gradient after cardiomyocytes were treated with leptin for 5 min, demonstrating subcellular translocation of RhoA. Treatment with MβCD, 50 ng/ml C3 exoenzyme (a RhoA inhibitor) or 50 nM latrunculin B (actin filaments depolymerization agent) significantly attenuated leptin-induced RhoA translocation into caveolae fractions. Moreover, Western blot analysis showed that leptin-dependent activation of PI3K (116%; p<0.05), Akt (115%; p<0.05) and RhoA (330%; p<0.05) were significantly inhibited by 50 μM LY294002, a specific PI3K inhibitor. In addition, LY294002 significantly attenuated leptin-induced increases in cell surface area and in leucine incorporation. Furthermore, we found that leptin-induced activation of p38 (189%; p<0.05) and ERK1/2 (220%; p<0.05) was associated with p38 MAPK but not ERK1/2 nuclear translocation. MβCD, C3 exoenzyme and LY294002 potently attenuated leptin-induced p38 MAPK nuclear translocation.

Conclusions
: Our results demonstrate that caveolae, the PI3K/Akt/RhoA pathway and p38 MAPK nuclear translocation play a pivotal role in leptin-induced cardiomyocyte hypertrophy.
Abstract 144: Erythropoietin Induces Positive Inotropy And Lusitropy Mediated By Phosphatidylinositol 3-kinase And Novel PKC Isoforms In Murine Cardiomyocytes
Authors: Hefer David , Fishbaugher David E , Tremble Sarah M , LeWinter Martin , Palmer Bradley M , VanBuren Peter
Published: July 2021

Introduction

Clinical studies indicate a potentially beneficial effect of erythropoietin (EPO) in patients with anemia and heart failure. Moreover, EPO is known to be cardioprotective in ischemia-reperfusion models, an effect mediated through a cardiac EPO receptor. However it is not known if EPO has a direct effect on cardiac contractility.

Methods

Isolated cardiomyocytes were obtained from C57BL/6 mice and exposed to either 50 U/mL of EPO or to a buffer solution. Cells were paced at 8 Hz. Sarcomere shortening dynamics were measured using a Fourier video transformation method. Global intracellular Ca
2+
dynamics were determined after loading cells with fura 2-AM. EPO concentrations from 0.1 – 50 U/mL and exposure times from 0 – 90 min were used for dose finding and time course experiments. The phosphatidylinositol 3-kinase (PI3K) blocker Wortmannin, the non-isozyme specific PKC blocker Chelerythrine or the PKC α and β blocker Gö6976 were administered concurrently with EPO to determine the signaling pathways involved.

Results

In control cells peak sarcomere shortening was 2.3 ± 0.3 %, while in EPO treated cells it was 4.4 ± 0.5 % (P=0.007, N=40 cells in each group from 5 hearts). Baseline sarcomere length was 1.55 ± 0.04 μm in controls compared with 1.72 ± 0.04 μm in EPO cells (P=0.008). Both shortening velocity [2.2 ± 0.3 μm/s versus 4.2 ± 0.5 μm/s (P=0.01)] and relengthening velocity [1.3 ± 0.2 μm/s versus 3.5 ± 0.5 μm/s (P=0.002)] were higher with EPO treatment. Ca
2+
dynamics studied in 25 cells in each group showed no differences between EPO treated and control cells. Positive inotropic and lusitropic effects occurred at EPO concentrations above 1 U/mL and after an incubation period of at least 30 min. The EPO mediated increase in peak sarcomere shortening was abrogated by concurrent PI3K blockade or by non-isozyme specific PKC blockade. However, it was preserved if only the classical PKC isozymes αand β were blocked.

Conclusions

In addition to its antiapoptotic and cytoprotective effects, EPO has direct positive inotropic and lusitropic effects in single murine cardiomyocytes. These are mediated by PI3K and novel PKC isoforms and are independent of changes in intracellular Ca
2+
handling, suggesting a PKC δor PKC ϵ mediated increase in myofilament contractile function.
Abstract 383: Heart-Kidney: Myocardial Infarction Mediates Renal Fibrosis and Activates Renal Molecular Remodeling in the Absence of Heart Failure
Authors: Martin Fernando L , Huntley Brenda K , Harders Gerald E , Sandberg Sharon M , Chen Horng H , Burnett John C
Published: July 2021

Background
: Studies in human myocardial infarction (MI) suggest that even in the absence of heart failure (HF) alterations in renal function may occur and contribute to poor outcomes. After MI a decline in renal function may be seen acutely by mechanisms which are unclear. The long term consequences of MI upon renal function and structure remain poorly defined. We hypothesized that even without pre-existing renal disease, renal functional and structural changes would be present following MI.

Methods
: Cardiorenal function and structure were assessed in Wistar rats, Sham (S; n=10) and MI groups (n=9) 3 weeks after MI. GFR was determined by inulin clearance. Blood was obtained for PRA and aldosterone. Hearts and kidneys were harvested for histological analysis. Cardiac function was assessed by echo. Genome-wide microarray analysis was performed on kidney cortex (KC) and medulla (KM) (Affymetrix GeneChip® Rat Genome 230 2.0).

Results
: EF decreased after MI (S:62.8±2.3, MI:42.8±6.5 %, p<0.01) and LVEDd increased (p<0.005) PRA and aldosterone activation were absent. Blood pressure (BP) was not different between groups. There was no HF as sodium and water excretion was maintained. GFR tended to decrease (S:2.9±0.3, MI:2.4±0.2 ml/min, NS). Picrosirius Red staining for collagen in the KC and KM after MI showed greater fibrosis especially in the RM (KC S:1.1±0.2, MI:3.5±0.6 %, p<0.001 and KM S:1±0.2, MI:18.8±6 %, p<0.005). Microarray analysis revealed that 303 genes significantly changed in KM and 407 genes in the KC after MI (1.5 fold, P<0.05). Gene dysregulation was related to cell proliferation, metabolic processes and cell communication (Z value>2).

Conclusion
: We conclude that experimental MI results in renal structural remodeling characterized by renal cortical and medullary fibrosis with a mild reduction in GFR and extensive modulation of molecular pathways related to renal growth and metabolism. This investigation provides evidence for a heart-kidney connection after MI by mechanisms which remain to be defined. We also conclude that therapies for MI targeting the heart also should be evaluated for properties of renoprotection.
Abstract 2706: Neurocognitive Deficits Associated with Advanced Heart Failure
Authors: Ginsberg J. P , Black A. T , Laws F. A , Fridriksson J. , Bonilha L.
Published: July 2021

The measures of general cognition which have previously been used to demonstrate cognitive impairment in patients with congestive heart failure (CHF) provide only broad indications of what cognitive function(s) in particular are impaired. The objectives of this study are:

quantify the severity of neurocognitive impairment;

use specific neurocognitive subtests to identify what functions are impaired;

use fMRI to identify brain regions putatively involved in neurocognitive impairments of patients with advanced CHF.

Hypoperfusion associated with CHF has been thought to be the primary cause of neuropathology in this population. We tested the hypothesis, suggested by our own preliminary data, that Verbal Fluency is impaired relative to Picture Naming and pathology of frontal lobe function is involved. Veterans with NYHA class III or IV CHF from our Advanced Heart Failure Clinic were given several cognitive tests, including the Addenbrooke Cognitive Exam (ACE). The ACE is a validated indicator of dementia comprised of four indices: Verbal Fluency, Language (Naming), Orientation, and Immediate Memory. Follow-up fMRI while performing Verbal Fluency and Picture Naming tasks was conducted to localize abnormalities of brain activation. Results showed that 64.5% of the group (n = 31, age = 62.3 (11.4) years) met the ACE cut-off score criterion of probable dementia (Total Score less than or equal to 88). Significantly lower scores on Verbal Fluency (p = .01), Language (p = .02), and Immediate Memory (p = .00), but not Orientation, were found in the probable dementia subgroup compared to the cognitively intact subgroup. After partialling out dementia status, ACE Total Score significantly correlated (r(31) = .31, p = .05) with cardiac output (measured with bioimpedance plethysmograhy). The fMRI procedure was administered on 7 patients. Activation patterns revealed absence of frontal activation (Brodmann Area 46) on Verbal Fluency relative to Picture Naming. In conclusion, many advanced heart failure patients appear to be undergoing a dementing process, and neurocognitive and neuroimaging results are consistent in suggesting impairment of explicit word generation and retrieval, but not semantic knowledge, with associated frontal lobe dysfunction.
Abstract 2711: The Modification Of Collagen Type I Turnover Is Associated With Long-term Response To Cardiac Resynchronization Therapy
Authors: Lopez-Salazar Begoña , Macias Alfonso , Gavira Juan Jose , Diez-Martinez Javier , Garcia-Bolao Ignacio
Published: July 2021

We investigated whether modification of collagen type I turnover is related to the long-term response to cardiac resynchronization therapy (CRT).

Methods and Results: Serum carboxy-terminal propeptide of procollagen type I or PICP (a marker of collagen type I synthesis), carboxy-terminal telopeptide of collagen type I or CITP (a marker of collagen type I degradation), matrix metalloproteinase (MMP)-1, -2, -9 and tissue inhibitor of MMP (TIMP)-1, were measured in 54 patients (35 responders) at baseline and after 1 year of CRT. At baseline, PICP and the ratio PICP: CITP were higher (p < 0.01) in responders than in nonresponders. At 1-year, both PICP (p < 0.005) and the ratio PICP:CITP (p < 0.05) decreased in responders, while increased in nonresponders (p < 0.005 and p < 0.05, respectively). MMP-1 (p < 0.05), MMP-9 (p < 0.005), and the ratio MMP-1:TIMP-1 (p < 0.01) increased, while TIMP-1 decreased (p < 0.005) in responders, but remained unchanged in nonresponders. The ratio PICP:CITP correlated inversely with ejection fraction (r = -0.501, p < 0.01) and directly with left ventricular end-diastolic diameter (r = 0.376, p < 0.05) in responders after CRT. Direct correlations were found between MMP-1, and -9 and ejection fraction (r = 0.315, p < 0.05, r = 0.516, p < 0.01) in responders after CRT.

Conclusions The ability of CRT to modify collagen type I turnover (i.e. decreasing synthesis and increasing degradation) is associated with its long-term response.
Abstract 2729: Atrogin-1 and MuRF1 Mediate Degradation of Cardiac Myosin-binding Protein C by the Ubiquitin-Proteasome System
Authors: Mearini Giulia , Gedicke Christina , Krämer Elisabeth , Buck Friedrich , Cao Peirang , Witt Christian , Lecker Stewart , Labeit Siegfried , Eschenhagen Thomas , Carrier Lucie
Published: July 2021

Background.
Familial hypertrophic cardiomyopathy (FHC) is a sarcomeropathy frequently associated with cardiac myosin-binding protein C (cMyBP-C) gene mutations. Most of them result in a frameshift and C-terminal truncated proteins. However, truncated mutants were not detected in myocardial tissue of FHC patients. A recent study showed that a truncated cMyBP-C (M7t) is rapidly and quantitatively degraded by the ubiquitin-proteasome system (UPS) after adenoviral gene transfer in neonatal rat cardiac myocytes (NRCM). Since the diversity and specificity of UPS regulation lies in E3 ubiquitin ligases, which specifically target proteins and direct the ubiquitination process, the present study investigated whether the sarcomere-specific E3 ligases, atrogin-1 and MuRF1, mediate degradation of wild-type (WT) and truncated M7t cMyBP-C.

Methods and Results.
NRCM were co-infected with atrogin-1 and WT or M7t cMyBP-C adenoviruses. Both overexpressed WT and M7t were co-immunoprecipitated with atrogin-1 suggesting that both forms of cMyBP-C interact with atrogin-1. However, whereas the amount of overexpressed WT cMyBP-C did not change, the M7t protein level was 80% lower in NRCM infected with atrogin-1 than without. This suggests that atrogin-1 is the E3 ligase mediating proteasome degradation of truncated M7t cMyBP-C only. We then investigated whether MuRF1 could regulate the level of endogenous cMyBP-C in MuRF1-KO mice and compared to WT. The heart to body weight ratio and the chymotrypsine-like activity of the proteasome were similar in KO and WT mice. The mRNA levels of cMyBP-C, and other E3 ligases, atrogin-1 and MuRF3, were similar between KO and WT ventricles. Strikingly, the protein level of cMyBP-C was 150% and 30% higher in neonatal and 24 wks-old KO compared to age-matched WT mice.

Conclusion
. These data suggest that

atrogin-1, located at the Z-band, mediates the proteasome degradation of truncated M7t cMyBP-C resulting from a FHC mutation,

the lack of MuRF1 is not compensated by other E3 ligases and is not associated with hypertrophy in KO mice, and

most importantly, MuRF1, mainly located at the M-band, specifically regulates the protein level of cMyBP-C.
Abstract 386: A Novel Aquaretic and Glomerular Filtration Rate Enhancing Peptide Without Vascular Vasodilatory Actions in Experimental CHF.
Authors: Chen Horng H , Pan ShuChong , Burnett John C , Simari Robert D
Published: July 2021

BACKGROUND:
BNP is a cardiac peptide with vasodilatory, natriuretic and diuretic properties. Recent studies have suggested that its vasodilatory hypotensive properties may limit the renal actions of BNP, especially in patients with borderline low blood pressure. We have recently identified an alternatively spliced transcript for BNP (ASBNP) that includes a unique and distinct longer carboxyl-terminus consisting of 34 amino acids. Based upon preliminary studies, we generated a truncated form (ASBNP2.1) that contains the first 16 amino acids of the C-terminal of ASBNP.

METHODS:
We determined the cardiorenal and humoral actions of intravenous infusion of ASBNP2.1 at 2 pmol/Kg/min, 10 pmol/Kg/min and 100 pmol/Kg /min in 10 dogs with rapid ventricular pacing induced overt CHF (240 bpm for 10 days). * p<0.05

RESULTS:
IV infusion of ASBNP 2.1 increased aquaresis (from 0.19±0.04 to 0.32±0.07, 0.46±0.11 and 0.39±0.09 ml/min*) without a significant change in urinary sodium excretion. Importantly, ASBNP 2.1 enhanced glomerular filtration rate (GFR), from 31±4 to 47±8, 69±10 and 56±9 ml/min*. These renal actions were associated with increases in urinary BNP*, ANP* and cGMP* excretion. BNP 2.1 did not have any systemic vasodilatory action resulting in no change in mean arterial blood pressure or cardiac-filling pressures even at the highest dose. There was not change in serum sodium concentration.

CONCLUSION:
We report for the first time that this novel peptide based upon ASBNP has potent aquaretic and GFR enhancing actions without the vasodilatory hypotensive properties in an experimental model of overt CHF. The lack of vasodilatation but with renal actions also suggest that the C-terminus plays a key role in the vascular actions of this peptide offering new insights into vascular-renal structure function of BNP and related peptides. This renal specific peptide may have potential therapeutic benefit in states of renal dysfunction with volume overload to enhance GFR and water excretion without the detrimental side effect of hypotension.
Abstract 2750: Multi-detector Computed Tomography Is An Accurate Screening Imaging Modality For Detection Of Thrombus In Patients Undergoing Catheter Ablation Of Atrial Fibrillation
Authors: Martinez Matthew W , Kirsch Jacobo , Williamson Eric E , Cha Yong-Mei , Friedman Paul A , Asirvatham Samuel J , Ommen Steve R , Callahan Mark J , Syed Imran S , Feng DaLi , Beinborn Douglas S , Packer Douglas L , Brady Peter A
Published: July 2021

Introduction Multi-detector computed tomography (MDCT) is commonly used to identify pulmonary vein and left atrial anatomy prior to catheter ablation for atrial fibrillation (CAAF). Additionally, transesophageal echocardiography (TEE) is utilized to exclude left atrial/left atrial appendage thrombus (ICT). Whether MDCT alone can be used to exclude thrombus obviating the need for TEE is unknown.

Methods All Pts referred for CAAF at Mayo Clinic between March 2004 and October 2006 were included. Clinical data (including CHADS score), 64 slice MDCT (non-ECG gated), TEE and intra-cardiac echocardiograph (ICE) were all performed and recorded. Image data was reviewed independently and blinded. The left atrial appendage (LAA) was defined as fully opacified or underfilled. An underfilled LAA was further interrogated using a region of interest over the filling defect and mean attenuation in Hounsfield Units (HU) were recorded.

Results In total 400 Pts (mean age 56 ± 10 yrs; 76% male; EF 56 ± 10 % ) were included. 362 had no ICT by TEE nor filling defect by MDCT. 38 patients had an underfilled LAA in whom ICT was confirmed by TEE in 7. Sensitivity and specificity of MDCT for ICT was 100% and 92% respectively with a NPV of 100%. In 19 Pts with underfilled LAA’s, a mean LAA emptying velocity was found to be significantly reduced at 26 cm/s (6 – 61 cm/s). Those with a thrombus had a mean attenuation value below 70 HU. CHADS2 score was higher (2.0 versus 1.0) in Pts with LAA filling defect versus those without LAA filling defect. All Pts with confirmed thrombus were taking Warfarin. ICT was not seen in any Pts aged <52 yrs with CHADS score ≤1.

Conclusions Sensitivity and specificity of MDCT for detection of LAA thrombus is high. LAA filling defects on MDCT correlate with low emptying velocities by TEE and low attenuation value in HU. These data would suggest that in the absence of MDCT filling defect, no further imaging is required. TEE should be utilized prior to CAAF to investigate MDCT filling defects.

Multidetector Computed Tomography for the Detection of LAA Thrombus
Abstract 2769: Impaired Skeletal Muscle Oxygen Utilization Contributes to Exercise Intolerance in Barth Syndrome
Authors: Spencer Carolyn T , Bryant Randall M , Byrne Barry , Heal Elisabeth , Margossian Renee , Cade W. Todd
Published: July 2021

Objective
s: Barth Syndrome (BTHS) is an X-linked mutation in the TAZ gene characterized by cardiolipin deficiency, mitochondrial dysfunction and cardio-skeletal myopathy. We hypothe- sized that abnormal skeletal muscle oxygen (O
2
) utilization contributes to exercise intolerance in BTHS.

Methods
: Boys with BTHS (n=13) and healthy male controls (n=7) performed a graded exercise test on a cycle ergometer with continuous metabolic and EKG monitoring. Near infrared spectroscopy (NIRS), an indirect measure of tissue O
2
saturation and index of skeletal muscle O
2
utilization, was applied to the vastus lateralis during exercise. Cardiac function in BTHS was assessed by echocardiography and serum BNP to examine the relationship between resting cardiac function and exercise capacity in BTHS.

Results
: Age (16±5 vs 13±3 years; p=0.22), BMI (17±3 vs. 20±5; p=0.14) and BSA (1.0±0.5 vs 1.2±0.6 m
2
; p=0.3) were not different between BTHS and controls. BTHS had lower peak VO
2
(19±6 vs. 52±6 ml/kg/min, p < 0.001), lower % of predicted peak VO
2
(40±10% vs. 115±12%, p=0.0004), lower peak work rate (58±18 vs. 205±69 watts, p=0.0004), and lower peak O
2
pulse (4.6±1.6 vs. 14±6 ml O
2
/kg/beat, p< 0.00001) than controls. Peak HR in BTHS was lower but remained within normal peak predicted rate (172±14 vs. 197±11 bpm, p=0.001). Vastus lateralis tissue O
2
saturation at peak exercise decreased from baseline in controls as expected (-18±16%, p<0.001) but paradoxically increased from baseline in BTHS (+17±14%, p<0.03, p=0.0005 BTHS vs. controls) indicating impaired muscle O
2
utilization. Absolute (r= - 0.70, p<0.0001) and percent (r= - 0.70, p<0.001) change in NIRS from baseline was negatively associated with peak VO
2
. There was no correlation between peak VO
2
and resting EF (55±7%; r=0.12), SF (30±4%; r= -.26), myocardial performance index (0.4±0.1; r= -.3) or serum BNP (232±381; r=0.1).

Conclusion
: O
2
consumption during exercise in BTHS is severely reduced and caused, at least in part, by impaired skeletal muscle O
2
utilization. Resting cardiac function is not related to O
2
consumption in BTHS but cardiac dysfunction during exercise in BTHS is not excluded without further studies. Mitochondrial dysfunction likely mediates skeletal muscle O
2
utilization deficits during exercise in BTHS.