bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 17108: Exercised-Induced eNOS-NO Modulation of Microvascular Permeability in Mouse Hindlimb by MicroCT Imaging
Authors: Zhuang Zhen W , Simons Michael , Sinusas Albert J
Published: April 2024

Introduction:
There are controversies as to whether eNOS-derived NO functions as a permeability-increasing or -decreasing factor. These disputes might result from a lack of in vivo imaging system to monitor the dynamic changes of permeability. We hypothesized that microCT (μ CT) imaging would enable noninvasive in vivo spatial, temporal, and quantitative monitoring of permeability in the hindlimb.

Methods:
To test this hypothesis, we longitudinally monitored micro-molecular leakage in hindlimb ischemic (HLI) models of wild-type (WT, n=12) and eNOS
−/−
mice (n=12) at rest [sedentary (SED)] or with physiological stimulation [swimming (SW) training] on day 3 and 14. The same animals were subsequently evaluated by specimen μ CT with 20% Bismuth gelatin as a contrast agent for arteriogenesis and macromolecular leakage. Blood flow was assessed by laser Doppler Imaging in another group of mice (n=8/group). Immunohistochemical staining for capillary density was performed in additional mice (n = 4/group).

Result:
eNOS deficiency altered the pattern of microvascular permeability in the hindlimb. On day 3 in vivo μ CT showed WT-HLI-SED mice had a marked increase of late contrast enhancement (20 min) in the calf region. Swimming training reduced severity. In contrast, eNOS
-/-
-HLI-SED mice exhibited late enhancement at the site of pre-existing collaterals. Swimming resulted in a large area of increased permeability in the upper calf region. On day 14, eNOS
-/-
mice showed a shift of extravasation from the thigh to the calf and worsened after swimming compared to remarked recovery in WT mice. Moreover specimen μ CT demonstrated eNOS deletion resulted in bismuth particles leaking outside the vasculature in eNOS-HLI-SED mice and more serious in eNOS-HLI-SW mice while WT mice kept their vascular integrity on day 14. This enhanced leakage in eNOS
-/-
-HLI-SW mice was associated with decreased angiogenesis and dysfunctional arteriogenesis (increased arterioles with less perfusion).

Conclusion:
μ CT allowed longitudinally spatial and quantitative monitoring of in vivo permeability in model of murine hindlimb ischemia, and predicted matured arteriogenesis with exercise training and is eNOS-NO dependent.
Abstract 17128: Transapical Aortic Valve Implantation (TA-AVI) Using the SYMETIS ACURATE TA™ Transapical Aortic Bioprosthesis - 1 Year Outcomes
Authors: Kempfert Joerg , Rastan Ardawan , Holzhey David , Schoenburg Markus , Treede Hendrik , Thielmann Matthias , Sorg Stefan , Mohr Friedrich , Walther Thomas , van Linden Arnaud
Published: April 2024

OBJECTIVES:
Transapical aortic valve implantation (TA-AVI) is a standard approach for high-risk elderly patients using the balloon expandable Edwards SAPIEN prosthesis. As an alternative we are evaluating a new self-expanding transapical bioprosthesis in a First-In-Man (FIM) study.

METHODS:
This novel device (SYMETIS ACURATE TA™ Transapical Aortic Bioprosthesis), composed of a porcine biologic valve attached to a self-expandable nitinol stent, is unsheathed proximally towards the apex and is designed for anatomical orientation of the commissures and for subcoronary implantation. A unique two-step implantation procedure provides simple positioning and tactile feedback during implant.

RESULTS:
40 patients have been treated, patient age was 82.8±4 years, 60% were female, NYHA Class III/IV, logistic EuroSCORE was 21.5±10.9% and STS Score was 9.0±4.6%. All implants were delivered successfully in the intra-annular and subcoronary position. Two patients required a valve-in-a-valve (SAPIEN), one of which was followed with a conversion to conventional surgery. 95% of patients were treated off-pump. Two patients required a pacemaker implantation due to new onset AV-block post-implant. At 6 months post-procedure, this novel 2nd generation TA-AVI device highlights a PV leak rate of 0 - 1 in 97% of followed patients and functional improvement from baseline in 90% with a NYHA Class I/II. The pacemaker rate remains at 5%. Seven patients expired (respiratory complications=4, right heart failure=2, unclear=1). Two patients suffered a secondary stroke.

CONCLUSIONS:
The ACURATE TA™ has demonstrated proof of concept with promising clinical results in this FIM study. The 1 year data will be available in October 2011.
Abstract 17138: Pacemaker Utilization in Cohort of 85 Children with Congenital Central Hypoventilation Syndrome (CCHS) May Impact the Risk of Sudden Death
Authors: Tsao Sabrina , Webster Gregory , Patwari Pallavi P , Deal Barbara J , Weese-Mayer Debra E
Published: April 2024

Background:
Congenital Central Hypoventilation Syndrome (CCHS) is a rare disorder characterized by alveolar hypoventilation, autonomic dysregulation, and risk for prolonged sinus pause based on type of Paired-like Homeobox 2B (
PHOX2B
) mutation. Standard of care includes annual 72-hr Holter surveillance. Utility of implanted cardiac pacemakers (PM) and all-cause mortality have not been previously described.

Hypothesis:
Cardiac PM in CCHS will have minimal utilization and adverse effects, and may reduce mortality.

Methods:
CCHS diagnosis was confirmed with comprehensive clinical evaluation and (after 2003),
PHOX2B
testing. Indications for cardiac PM implantation, pacing burden and follow-up echo (to assess left ventricular dysfunction) were reviewed.

Results:
CCHS was confirmed in 85 pts (45% female). PM were implanted in 21 pts (mean age: 9 yr; range 0.8-22.6), all with
PHOX2B
20/26 or 20/27 genotypes (known to heighten risk for cardiac pauses). Nineteen of the 21 PM pts (90.5%) had mild, atypical symptoms; 6/19 (32%) had overt symptoms including life-threatening events or seizures. Subsequent to the 2008
PHOX2B
genotype/sinus pause risk publication (Pediatr Pulm 43:77-86), PM implantation was based on sinus pauses of ≥3 sec. In the pre-2008 cohort, all-cause mortality rate was 19.7% (12/61). In the 2008-present cohort, mortality rate was 2.9% (1/35)(p=0.03). Eleven pts overlapped cohorts; the 1 recently deceased PM pt had diffuse vasomotor instability, total gut aganglionosis, and continuous ventilator dependence. No device complications were observed in any pt. Mean burden of ventricular-pacing was 0.5% (range 0-2.4%). No ventricular dysfunction was noted in the 16/21 PM pts who had echo follow-up (mean follow-up 5.8 yrs, range 0.1-16.5).

Conclusions:
A strategy of annual 72-hr Holter monitoring and PM implantation for symptoms and/or asymptomatic pauses ≥ 3 sec is associated with reduced mortality in CCHS, though the reduction may be in part due to enhanced overall care during the study period. Devices had low utilization and complication rates and were not associated with ventricular dysfunction. We propose consideration of CCHS as a new category of pts who may require cardiac pacing to impact the risk of sudden death.
Abstract 17144: Assessment of Tissue Heating During Cardiac Radiofrequency Ablation Using Referenceless MRI Thermography
Authors: Kolandaivelu Aravindan , Zviman Menekem , Sena-Weltin Valeria , Halperin Henry
Published: April 2024

Introduction:
Imaging tissue heating during RF ablation may permit more accurate placement and titration of ablation lesions. Standard proton resonance frequency shift MRI thermography, however, is limited by sensitivity to physiologic motion and scanner phase drift between acquisition of ablation and reference pre-heating images. The aim of this study is to assess the feasibility of referenceless MRI thermography which addresses this limitation by eliminating need for a separate pre-heating image but has not yet been applied to cardiac ablation.

Methods:
An MRI compatible copper electrode catheter was inserted into the left ventricle in 6 dogs. Gradient recalled echo images were acquired while applying RF power in 3W increments until high impedance was reached. Gross pathology was obtained. The pre-heating image was estimated from the ablation image phase component (A) by unwrapping phase (B), masking the catheter tip region where heating was expected (C), and extrapolating phase from unmasked regions of the heart using a fourth order polynomial fit (D). Thermography images were then computed using standard methods (E). Thermography lesion extent was defined by tissue temperature above 50°C. Electrode artifact was defined by darkened myocardium adjacent to the catheter tip on the magnitude component of the ablation image.

Results:
Transmural lesion extent by referenceless MR thermography was within 20% of that obtained by pathology (inset F) in the four cases where the electrode artifact transmurality was less than 25%. However, thermography and pathology lesion extent differed by over 60% in the two cases where electrode artifact transmurality was greater than 40%.

Conclusion:
Referenceless MR thermography of cardiac RF ablation is possible and may permit more practical MR thermography monitoring of cardiac ablation. Reducing electrode artifact by using lower magnetic susceptibility materials appears required for more reliable temperature assessment.
Abstract 17170: Acute Aortic Intramural Hematoma: an Analysis from the International Registry of Acute Aortic Dissection
Authors: Harris Kevin M , Braverman Alan C , Pyeritz Reed , Myrmel Truls , Peterson Mark , Voehringer Matthias , Fattori Rossella , Januzzi James L , Gilon Dan , Montgomery Daniel , Eagle Kim A , Nienaber Christoph A , Isselbacher Eric M , Evangelista Arturo
Published: April 2024

Background:
Acute aortic intramural hematoma (IMH) represents an important subgroup of aortic dissection though controversy continues to surround the appropriate management.

Methods:
We evaluated patients with acute aortic syndromes in the IRAD registry (between 1996 and 2011) and examined differences between patients (based on the initial imaging test) with IMH or classic dissection (AD).

Results:
Of 2908 patients, 182 had IMH (72 type A (TA), 39.6%, 110 type B (TB), 60.4%). Patients with IMH were older in both TA (68.9 years vs. 61.4, p<0.001) and TB (69.3 vs 62.7, p<0.001), and more frequently female in TA (44.4% vs 32.3%, p=.031). Patients presented with similar symptoms such as severe pain in TA (98.4% vs 91.6%, p=NS) and TB (95.7% vs 93.0%, p=NS). Patients with TA IMH were less likely to present with aortic regurgitation (37.3% vs 54.8%, p=.008) or pulse deficits (16.7% vs31.5%, p=.015). Patients with TA IMH were more likely to have periaortic hematoma (47.5% vs 19.9%, p<0.001) and pericardial effusion (60.0% vs 41.2%, p=.002). Patients with IMH were more likely than classic AD to be managed medically (TA, 22.2% vs 12.6%, p=.017, type B 85.5% vs 62.9%, p<0.001). Overall in-hospital mortality was similar for type A IMH (26.4% vs 26.4%, p=NS); those with type A IMH managed medically had significant mortality (37.5%) though less than those with classic AD (58.5%, p=NS). Those with type B IMH had lower in hospital mortality (4.5% vs 10.9%, p=.043) than classic AD. One year mortality was similar for both groups.

Conclusion:
The IRAD registry includes 182 cases of IMH and represents the largest series to date on this important variant of AD. Acute IMH has similar presentation to classic AD but is more frequently complicated with pericardial effusions and periaortic hematoma. Patients with IMH have similar mortality to those with classic AD. Although a substantial subgroup of type A patients with IMH are managed medically, they do have a significant hospital mortality.
Abstract 17173: Caloric Restriction Protects Against Aging Cardiomyopathy, But Not Longevity
Authors: Yan Lin , Gao Shumin , Ho David , Ge Hui , Wang Chunbo , Tian Yimin , Vatner Dorothy E , Vatner Stephen F
Published: April 2024

Caloric restriction (CR) is the most common model of enhanced longevity. However, this has been questioned in some mouse models. The goal of this study was to determine if CR protected against aging cardiomyopathy and whether this could account for the enhanced longevity of CR. We studied 2 models of CR, both with 40% calorie reduction; one initiated in 2 month old 129 SVJ mice and continued for 24 months, long term (LT) CR; and the other initiated in mice at 20 months of age, when cardiomyopathy was already developing, and continued for 2 months, short term (ST) CR. The older mice at 2 yrs on normal diet (ND) developed aging cardiomyopathy, compared to young ND mice: left ventricular (LV) systolic function, i.e. LV ejection fraction, was depressed (58±4%
vs
71±1%, p<0.05). In addition the cardiomyopathy was characterized by increased myocyte apoptosis (0.29±0.04
vs
0.05±0.02 cells/mm
2
, p<0.05) and LV hypertrophy (LVH), as evidenced by increased LV/ tibial length (TL) (5.7±0.4
vs
4.6±0.1, p<0.05), compared to young ND mice. With LT CR, aging cardiomyopathy did not develop; LV ejection fraction (71±1%), myocyte apoptosis (0.14±0.07 cells/mm
2
), and LV/TL (4.2±0.2) were significantly improved compared to old ND mice. Surprisingly, ST CR induced similar salutary effects as LT CR with preserved LV ejection fraction (74±1%), reduced myocyte apoptosis (0.07±0.02 cells/mm
2
) and LV/TL (5.0±0.2). There were also significant decreases in α-tublin (48%), β-tublin (67%) and cleaved desmin (43%), with an increase in intact desmin (32%), reflecting altered cytoskeletal proteins, as well as an increase in antioxidants MnSOD (31%) and catalase (51%). Even more surprisingly, neither LT, nor ST CR improved longevity; in fact, more mice died with CR (55%), than with ND (45%) over the 2 year monitoring period. Thus, CR prevents the development of aging induced cardiomyopathy, potentially by correcting aging induced alterations in cardiac cytoskeletal proteins and increased resistance to oxidative stress. Of therapeutic relevance, instituting this intervention even in later life can rapidly correct the cardiomyopathy of aging. Surprisingly, CR does not enhance longevity in this mouse model, despite prevention of aging cardiomyopathy.
Abstract 17179: Tissue Factor Pathway Inhibitor Regulates Vascular Patterning in the Developing Zebrafish
Authors: Hoffman Scott J , Holroyd Eric W , Pierret Christopher K , Bedell Victoria M , Ekker Stephen C , Simari Robert D
Published: April 2024

Background:
The tissue factor pathway regulates vascular structure in the adult through regulation of thrombin generation and signaling. Deletion of tissue factor pathway inhibitor (TFPI) in the mouse results in early intrauterine lethality, precluding study of vascular development. In addition, the carboxyl terminus of TFPI may have a TF-independent effect on vascular structure. We sought to determine the role of TFPI and its carboxyl terminus in vascular development of zebrafish.

Methods and results:
TFPI mRNA localization studies demonstrated expression in the developing kidney, gut, and vasculature of the zebrafish. We further assessed the role of TFPI in zebrafish angiogenesis, by injecting translational and splice-inhibiting morpholino (MO) oligonucleotides directed against zebrafish TFPI mRNA into embryos from the double transgenic zebrafish
Tg(Fli1GFP); Tg(GATA1dsRed)
expressing GFP in vascular endothelium and dsRed in erythroid cells. Knockdown of TFPI protein expression was subsequently confirmed by immunoblotting. In a dose-dependent manner, multiple non-overlapping MOs targeting the translation initiation site of TFPI independently and synergistically led to the formation of abnormally targeted intersegmental arteries which crossed somite boundaries by 48 hours post fertilization (hpf). Additionally, a plethoric caudal vein plexus with increased honeycombing was present by 24 hpf. This latter aspect of the phenotype was most striking after a MO targeted against a splice site involving the Kunitz 3 and carboxyl terminus domains of zebrafish TFPI was injected alone.

Conclusions:
TFPI is expressed during zebrafish development. Morpholino knockdown of TFPI expression alters both arterial and venous patterning in the developing zebrafish, indicating a fundamental role for TFPI in targeting of newly-formed blood vessels. Moreover, different domains of the TFPI protein may preferentially act on distinct vascular networks.
Abstract 17184: Depression Recognition and 1-Year Survival in Acute Myocardial Infarction Patients
Authors: Smolderen Kim G , Buchanan Donna M , Gosch Kensey , Whooley Mary , Chan Paul S , Vaccarino Viola , Parashar Susmita , Shah Amit , Ho Michael , Spertus John A
Published: April 2024

Background:
Depression among acute myocardial infarction (AMI) patients is prevalent and associated with an adverse prognosis. Although depression often remains undetected in AMI patients, there is still debate about the importance of screening for depression at the time of AMI. Defining the prognostic importance of unrecognized depression may support better efforts to increase its recognition.

Methods:
In the prospective TRIUMPH study, 4062 AMI patients from 24 US hospitals completed the Patient Health Questionnaire-9 (PHQ-9) during their index AMI admission. Depression was defined by a PHQ-9 score of ≥10. Depression was considered to be recognized by the treating team if it was documented in the patient's chart (discharge depression diagnosis, discharge anti-depressants, referrals for counseling). Follow-up interview data on use of anti-depressants and/or counseling was collected at 1 and 6 months. One-year mortality was compared between: (1) recognized depressed; (2) unrecognized depressed; and (3) non-depressed (PHQ-9<10; reference) patients, adjusting for demographics, AMI severity, and clinical factors. Sensitivity analysis additionally adjusted for follow-up depression treatment.

Results:
Although 759 (19%) patients were depressed, only 231 (30%) were recognized. As compared with non-depressed patients, recognized depressed AMI patients had similar 1-year mortality rates (6.7% vs. 6.1%, adjusted HR=1.12, 95%CI 0.63-2.00), whereas those with unrecognized depression had increased mortality (10.8% vs. 6.1%, HR=1.92, 95%CI 1.39-2.64). Recognized vs. unrecognized depressed patients received more depression treatment after discharge (70% vs. 24%), but this did not attenuate the increased hazard for the unrecognized patients.

Conclusion:
AMI patients with recognized depression had similar survival compared with non-depressed patients, but patients with unrecognized depression had worse survival. These findings raise the possibility that recognizing depression during AMI care may be crucial to better risk-stratify depressed AMI patients so that more aggressive cardiac treatments can be considered to reduce their elevated mortality risk.
Abstract 17191: Bolus Administration T1 Mapping as a Marker of Interstitial Myocardial Fibrosis in Severe Aortic Stenosis
Authors: Jabbour Andrew , Ettles Callum , Ismail Tevfik , Gulati Ankur , Ferreira Pedro , Wage Ricardo , Zaman Saman , Croisille Pierre , Shakespeare Carl , Mohiaddin Raad , He Taigang , Pennell Dudley , Firmin David , Prasad Sanjay
Published: April 2024

Introduction:
Aortic stenosis (AS) is associated with increased interstitial myocardial fibrosis (IMF). This is detectable by cardiovascular magnetic resonance (CMR) after gadolinium infusion. T1-mapping-derived partition coefficients (λ) and extracellular volume fractions (Ve) have also been shown to correlate with IMF after a simple bolus administration of gadolinium. We hypothesized that the λ and Ve would also detect interstitial expansion in severe AS patients compared to healthy controls and that these measures would correlate with abnormal myocardial strain using a high temporal-resolution tagging sequence.

Methods:
A Modified Look-Locker Inversion Recovery (MOLLI) sequence was used to generate eleven T1-weighted images. Myocardial and blood pool T1 values were derived by fitting a signal intensity-time curve using CMR42®. The λ was determined by plotting (1/T1
myo
vs. 1/T1
blood pool
) at various time points once contrast equilibrium was reached. Ve was derived accounting for the hematocrit. Short-axis T1 maps were acquired using a 1.5T scanner (Siemens) before and 1,2,5,8,15,20,25 and 30 minutes after contrast. Myocardial tagging images were acquired using single- and multiple-breath-hold CSPAMM sequences in multiple planes and analysed with inTag® (Lyon, France).

Results:
Twenty-three subjects (age 57 (16), mean (SD); male n=13; severe AS n= 8, healthy control n=15) were recruited. Subjects with severe AS displayed higher λ (0.35 (0.11) vs 0.27 (0.04); P=0.02) and Ve (0.19 (0.08) vs 0.13 (0.03)).The λ and Ve correlated with indices of reduced myocardial function including reduced circumferential δ strain (r=-0.69, p=0.001), angle peak strain (r=-0.48, p=0.04) and radial δ strain (r=-0.59, p=0.03); and increased left atrial dilatation (r=0.64, p=0.001).

Conclusions:
T1-mapping-derived λ and Ve are significantly elevated in patients with AS compared to healthy controls and correlate well with indices of reduced myocardial performance. This difference was quantifiable after a simple bolus administration of gadolinium. Further histological validation is required; however, T1-mapping λ and Ve derivation after bolus gadolinium administration is clinically practical and holds promise for the detection of IMF in severe AS.
Abstract 17197: Closure of Multiple Atrial Septal Defects with the Helex Device
Authors: Mehta Smita , Hill James A , Qureshi Athar M , Latson Larry A , Prieto Lourdes R
Published: April 2024

Background:
The performance of the Helex Septal Occluder (HSO) for closure of fenestrated atrial septum/multiple ASDs (mASDs) has not been evaluated. We sought to review our experience with closure of mASDs with the HSO.

Methods:
We identified 48 patients with mASDs who underwent percutaneous closure between 6/2001 and 5/2011. Number and size of ASDs, number of implanted HSOs, residual shunt, and complications were recorded.

Results:
Of 48 patients, 27 had defect closure with ≥ 1 HSO. Indication for closure was RV enlargement (RVE) in 24 (89%) and cryptogenic neurologic event in 3 (11%). Median age was 9.1 (1.9-66.2) years, median weight 30.7 (12.2-99.5) kg. Six patients (22%) weighed < 20 kg. Median number of ASDs was 2 (2-≥5). Median stop-flow diameter in 25/27 patients was 12 (6-24) mm. Two patients had multiple small defects that were not sized. One HSO was implanted in 21 patients (78%), and 2 HSOs in 6 patients (22%). Procedural complications included device embolization in 2 patients, and both were retrieved percutaneously with successful deployment of another HSO. Residual shunt immediately post-closure was absent in 5/27 (19%), trivial in 15/27 (55%), small in 6/27 (22%), and moderate in 1/27 (4%). The median length of follow-up was 2 (0-9) years. Residual shunt at last follow-up was absent in 13/27 (48%), trivial in 8/27 (30%), small in 5/27 (18%), and moderate in 1/27 (4%). No complication occurred during follow-up. Of the 24 patients with RVE before closure, 2 are recent without follow-up and 1 is lost to follow-up. RV size normalized in 20/21 (95%) patients. No patient with a prior neurological event had a recurrence. The patient with moderate residual shunt and RVE had 1 HSO, and placement of a second HSO is planned.

Conclusions:
We conclude that closure of mASDs with 1 or more HSOs is effective with a low complication rate. The complication observed, embolization, did not significantly affect outcome in this series, as percutaneous retrieval was successful. In addition, the low profile of the HSO may facilitate safe implantation of multiple devices in smaller patients.
Abstract 17218: ATP Binding to Akt Kinases Confer Dephosphorylation Resistence in Caveolin 3/ Membrane Rafts
Authors: Chan Tung , Myers Valerie , Zhang Jin , Dumitru Calin , Spring Maureen , Song Jianliang , Li Xue , Pascal John , Rodeck Ulrich , Cheung Joseph , Feldman Arthur
Published: April 2024

Introduction:
Akt kinase activation loop phosphorylation (T308 in Akt1) in vivo is regulated by the opposing activities of kinases and phosphatases. To investigate this regulation balance, we showed that the translocation of Akt1 to caveolin-3 (Cav3) containing membrane caveolar/rafts markedly reduced its dephosphorylation by cellular phosphatases. Furthermore, this dephosphorylation resistence was regulated by Akt kinase binding to ATP or ATP-competitive inhibitors.

Methods and Results:
In H9C2 cells or in adult cardiac myocytes, we showed that Cav3 overexpression cooperated with insulin to increase T308 phosphorylation by inhibiting Akt dephosphorylation. Cav3 overexpression is known to increase membrane caveolar/raft density. Conversely, treating cells with the cholesterol-depleting lipid raft inhibitor, methyl cyclodextrin (MβCD), enhanced Akt1 dephosphorylation. MβCD also enhanced the dephosphorylation of constitutively phosphorylated myristylated-Akt (Myr-Akt), suggesting that Cav3/lipid rafts protected Akt1 from dephosphorylation. Similarly, an Akt-specific ATP competitive inhibitor (A443654) also cooperated with insulin to increase T308 phosphorylation. Pharmacological and genetic data determined that dephosphorylation resistance depended on the binding of ATP or ATP-competitive inhibitors to Akt kinases. Finally, an in vitro reconstitution assay and mutational analysis revealed that R273 in Akt1 and corresponding R274 in Akt2 were essential for shielding the activation loop against dephosphorylation.

Conclusion:
R274 in AKT2, when mutated, is associated with causing autosomal-dominant severe insulin resistance and diabetes mellitus in humans. Our in vitro reconstitution system unambiguously reveals that after Akt binding to membrane Cav3 caveolar or rafts, these ATP and ATP-competitive inhibitors prevent activation loop dephosphorylation via phosphatase access restriction.
Abstract 17221: AMPK Regulation of Microtubule Dynamics in Cardiac Hypertrophy
Authors: Fassett John T , Xu Xin , Lu Zhongbing , Hu Xinli , Zhang Ping , Chen Yingjie , Bache Robert
Published: April 2024

Cardiomyocyte hypertrophy requires increased protein synthesis as well as remodeling/growth of the cytoskeletal networks necessary to support cell enlargement. AMPK is a metabolic sensor that couples cell growth to ATP levels. Whether AMPK regulates cardiomyocyte cytoskeletal dynamics and how this influences hypertrophy is not known. Here we used cultured neonatal cardiomyocytes and AMPK KO mice to examine the role of AMPK in cytoskeletal remodeling that occurs during hypertrophy. In cardiomyocytes exposed to hypertrophic stress (phenylephrine or constitutively active Raf), AMPK activation (AICAR 0.1-0.2 mM) or constitutively active AMPK had little effect on intermediate filaments or myofilaments, but did attenuate accumulation and stabilization of microtubules (AICAR reduced MT levels to 38% +/- 3.6 % and detyrosinated MTs to 14% +/- 11% of PE treated; p<.001). Importantly, AMPK reduction of microtubule stability occurred at low doses of AICAR that did not block mTOR/p70S6k signaling or translation, suggesting microtubule dynamics are an extremely sensitive target of AMPK. Interestingly, AMPK reduction of microtubules limited cardiomyocyte elongation, suggesting a mechanism by which AMPK influences cell morphology. In mice exposed to pressure overload (transverse aortic constriction;TAC), microtubule levels were exacerbated by AMPK alpha 2 KO as compared to WT mice (202 % +/- 42%; p=.047). Furthermore, microtubule levels exhibited a significant inverse correlation with LV ejection fraction (R
2
=.752; p<.001), suggesting microtubule densification may contribute to reduced contractile function in AMPK KO mice. Mechanistically, AMPK activation increased phosphorylation of Microtubule Associated Protein 4 (MAP4) at serine 768, which prevents its ability to stabilize microtubules. Phosphorylation of MAP4
Ser768
was reduced in AMPK KO mice, but increased in WT mice exposed to metformin, which also reduced MT stability. RNAi depletion of MAP4 in isolated cardiomyocytes further confirmed its important role in stabilizing microtubules during hypertrophy. Together, our data identify a novel protective role for AMPK in preventing aberrant stabilization and accumulation of cardiac microtubules in response to hypertrophic stress.
Abstract 17230: BMP9 Regulates Endothelin-1 Gene Transcription in Cooperation With TGF-β Signaling
Authors: Bagarova Jana , Paskin-Flerlage Samuel D , Lai Carol S , Bloch Kenneth D , Yu Paul B
Published: April 2024

Pulmonary arterial hypertension (PAH) is characterized by abnormal pulmonary vasoreactivity and pulmonary angiopathy, leading to progressively increased pulmonary resistance, right heart failure and high mortality. The mechanisms of PAH have not been fully elucidated, although dysregulated bone morphogenetic protein (BMP) signaling due to loss-of-function mutations in the gene encoding the BMP type II receptor (BMPRII) are implicated in heritable PAH. It has been recently reported that BMP9, a BMPRII ligand, regulates transcription of the potent vasoconstrictor and smooth muscle mitogen endothelin-1 (ET-1), an important mediator of PAH. BMP9 functions as a circulating vascular quiescence factor that promotes endothelial survival while inhibiting angiogenesis. We hypothesized that altered BMP signaling in pulmonary vascular endothelium may affect the regulation of ET-1 and thereby contribute to the pathophysiology of PAH. We found that stimulation of cultured human and murine lung microvascular endothelial cells with BMP9 activates both canonical BMP and TGF-β pathways via their respective effector molecules, SMAD1/5/8 and SMAD2/3. BMP9-induced transcription of ET-1 appeared to require coordinated activation of both BMP and TGF-β signaling pathways, based on the finding that ET-1 gene transcription was inhibited by selective small molecule inhibitors of BMP or TGF-β receptor kinases, by recombinant BMP receptor ectodomains, or by siRNA-mediated suppression of BMP or TGF-β type I receptor expression. In addition, functional analysis of the human ET-1 gene promoter revealed the presence of distinct
cis
-regulatory elements involved in BMP9- versus TGF-β-mediated activation of ET-1 gene transcription. Mutational inactivation of a novel BMP-responsive regulatory element, as well as known TGF-β-responsive elements, abolished ET-1 gene promoter activity in response to BMP9, underscoring further the cooperative nature of BMP and TGF-β signaling in ET-1 regulation. These results suggest that perturbation of BMP signaling may alter the regulation of ET-1 in the endothelium, impact endothelial and vascular homeostasis, and thus contribute to the pathogenesis of PAH.
Abstract 17263: Healthcare Contacts Before Sudden Out-of-Hospital Cardiac Arrest Can Help Identify Young Patients at Risk of Sudden Cardiac Death
Authors: Weeke Peter , Folke Fredrik , Gislason Gunnar H , Lippert Freddy K , Olesen Jonas B , Andersson Charlotte , Wissenberg Mads , Poulsen Henrik E , Nielsen Søren L , Køber Lars , Torp-Pedersen Christian
Published: April 2024

Background
The underlying etiology of sudden cardiac death varies with age and is likely to be reflected in type and number of healthcare contacts. We aimed to determine the specific type of healthcare contact shortly before out-of-hospital cardiac arrest (OHCA) across ages.

Methods
Patients with OHCA were identified in the nationwide Danish Cardiac Arrest Register and Copenhagen Medical Emergency Care Unit from 2001-2006. We matched every OHCA patients with 10 controls on sex and age. Healthcare contacts were evaluated 30 days before event by individual-level-linkage of nationwide registers. Healthcare contact associations to OHCA were evaluated using conditional multivariate logistic regression.

Results
We identified 16,924 OHCA patients, median age was 70.0 years (IQR: 59-80) and 65.8% were male. In general, the association between OHCA and hospital admissions and pharmacotherapy was more pronounced among the youngest (14-34 years) OHCA patients 30 days before OHCA compared to older patients (≥75 years): antidepressants (OR=4.5, CI:2.7-7.5 and OR=1.1; CI:1.0-1.2), sedatives and anxiolytics (OR=11.1, CI:6.8-18.4 and OR=1.1, CI:1.0-1.2), anti-psychotic medication (OR=5.6, CI:2.9-11.7 and OR=1.5, CI:1.3-1.7), bronchial dilators (OR=3.4, CI:1.9-6.0 and OR=2.1, CI:1.9-2.3), and corticosteroids (OR=4.0, CI:1.0-16.4 and OR=1.8, CI:1.6-2.0). Furthermore, patients aged <40 years were >6 times more likely to be in contact with the healthcare services (than the control population whereas OHCA patients >60 years were only 2 times more likely to be in contact with the healthcare services shortly before OHCA compared to the control population (Figure 1).

Conclusion
Young OHCA patients are far more likely to be in contact with the healthcare services compared with an age and sex matched control population suggestive of traits that make them stand out from the general population and make them potentially identifiable before cardiac arrest.
Abstract 17265: The Relationship Between Subclinical Coronary Artery Atheroscelrosis and Brain Ischemic White Matter Disease in Healthy Individuals from High Risk Families
Authors: Nyquist Paul A , Kral Brian G , Vaidya Dhananjay , Yanek Lisa R , Moy Taryn F , Fishman Elliot K , Becker Lewis C , Becker Diane M
Published: April 2024

Background:
Ischemic white matter disease (IWMD) is associated with incident stroke. Similarly subclinical coronary artery disease is associated with incident coronary artery disease (CAD) events. Although, atherogenesis in both vascular beds likely shares common mechanisms, the extent to which subclinical CAD is associated with preclinical IWMD in a young to middle-aged healthy asymptomatic high risk population with a family history of premature CAD remains unknown.

Methods:
We screened 405 apparently healthy participants in Genetic Study of Atherosclerotic Risk (GeneSTAR) (mean age 51.6 ± 10.6 years, 60% female, 36% African American) for CAD risk factors, and for the presence of calcified and noncalcified coronary plaque using dual-source 256 multi-detector cardiac CT angiography. The presence of IWMD was assessed by 3 Tesla brain MRI and the ischemic white-matter volume to brain volume (WVBV) ratio was calculated using direct measurements. A multivariate linear regression analysis predicting WVBV was performed for the presence of CAD, adjusting for age, sex, race, traditional CAD risk factors, and intrafamilial correlations using a generalized estimating equation (GEE).

Results:
Subclinical CAD was highly prevalent (43.0%). Individuals with coronary plaque had a higher ratio of WVBV (median 0.11, interquartile range [0.04 to 0.33]) as compared to those without coronary plaque (median 0.05 [0.01 to 0.14], p<0.001). In the fully adjusted analysis, the presence of subclinical CAD was a significant predictor of WVBV (p=0.05), as was age (p<0.001).

Conclusion:
This is the first study to show a strong association of subclinical CAD and occult ischemic white mater disease in healthy high-risk young to middle aged individuals, independent of traditional CAD risk factors, including age. The findings support the premise of shared causal pathways in the two vascular beds in families at increased risk for both CAD and stroke.
Abstract 17267: Enhanced Engraftment and Therapeutic Benefit of Human Cardiosphere-Derived Cells Delivered in an
In Situ
Polymerizable Hydrogel
Authors: Cheng Ke , Blusztajin Agnieszka , Shen Deliang , Smith Rachel R , Makkar Raj , Marbán Eduardo , Marbán Linda
Published: April 2024

Background:
The vast majority of cells delivered into the heart by conventional means are lost within the first 24 hours. Cardiosphere-derived cells (CDCs) face the same fate, suggesting that novel methods are needed to enhance retention.

Methods and Results:
We tested a cell-hydrogel delivery strategy. CDCs were grown from adult human cardiac biopsy specimens (n=7).
In situ
polymerizable hydrogels made of hyaluronan and porcine gelatin (HyStem-C™, Glycosan Biosciences) were formulated as a liquid at room temperature so as to gel within 20 minutes at 37°C. We verified that such a formulation could be passed through human injection catheters with full cell product recovery and viability.
In vitro
, average CDC viability in HyStem-C assayed using WST-8 was 87±9% after 72 hrs in culture, and remained high after one week (84±19%). Trans-membrane migration assays showed the migration capacity of CDCs was not compromised in the HyStem-C. Myocardial infarction was created in SCID mice and CDCs were injected intramyocardially in the infarct border zone. 24 hours after injection, real time PCR revealed a small fraction (5.8±2.2%, n=4) of CDCs delivered in conventional vehicle (PBS) engrafted. In contrast, engraftment of CDCs delivered in HyStem-C was increased by nearly an order of magnitude (35.0±25.2%, n=5, p<0.05). The superior engraftment persisted for at least 3 weeks (n=3; 1.2±0.4% vs. 5.9±0.5%, p<0.05). Cardiac echos (n=7-8 per group), analyzed in a blinded manner, revealed comparable LVEFs two hours post-MI, indicating similar ischemic injury among groups. At 3 weeks, LVEF deteriorated in the control (PBS only) group (-9.4±4.4%). In contrast, HyStem-C alone or CDC alone preserved LVEF (+0.5±8.6% and +5.8±5.3%, respectively), while HyStem-C + CDC resulted in a sizable boost in LVEF (+16.6±4.3%). Three weeks after treatment, the highest cardiac function was seen in the HyStem-C + CDC group (p<0.05 vs others). Quantitative morphometry revealed the greatest attenuation of LV remodeling in the HyStem-C + CDC group, with smallest infarct size and thickest infarct walls (n=4; p<0.05).

Conclusions:
A CDC/hydrogel formulation suitable for catheter-based intramyocardial injection exhibits superior engraftment and functional benefits relative to naked CDCs.
Abstract 17288: GTP Cyclohydrolase I Rescues microRNA-34a Impairment of Endothelial Progenitor Cell Angiogenesis in Aging
Authors: Chen Dandan , Zhao Ting , Li Jian , Chen Alex F
Published: April 2024

Introduction:
Endothelial progenitor cells (EPCs) are critically regulated by eNOS for their angiogenic functions. eNOS and its essential cofactor tetrahydrobiopterin (BH4) are reduced during aging, and aged EPCs exhibit decreased proliferation, migration and survival. We recently reported that microRNA 34a (miR-34a) induces EPC senescence and inhibits its angiogenesis by targeting silent information regulator 1 (SIRT1). However, whether miR-34a regulation of EPC angiogenesis involves eNOS and BH4 in aging is unknown. We hypothesized that miR-34a promotes impairment of EPC angiogenesis in aging, which could be rescued by GTP cyclohydrolase I (GTPCH I, the rate-limiting enzyme for BH4 biosynthesis).

Methods:
Bone marrow-derived EPCs from young (8-10 weeks) C57BL/6 (wild type, WT), GTPCH I transgenic (Tg-GCH, endothelial-specific GTPCH I overexpression), hph-1 (BH4-deficient), aged (18-20 months) C57BL/6 (WT) and eNOS/GCH double-transgenic (Tg-eNOS/GCH) mice (all males) were used.

Results:
Aged WT mice showed significantly impaired recovery of hindlimb ischemia, compared with young WT mice (0.40±0.13 vs. 0.68±0.12, n=3, p<0.05). Consistently, EPCs from aged WT mice showed impaired Matrigel angiogenesis (0.46±0.03 vs. 1.00±0.04, n=4, p<0.01). Reactive oxygen species (ROS) level was significantly elevated in EPCs from aged WT mice (~1.6 folds vs. young WT mice, n=3, p<0.05), accompanied by reduced GTPCH I expression (0.63±0.07 vs. 1.00±0.08, n=3, p<0.05). Suppression of miR-34a in EPCs from aged WT mice rescued their impaired angiogenesis, while overexpression of miR-34a in EPCs from young WT mice impaired their angiogenesis in vitro. Moreover, miR-34a expression was decreased in EPCs from aged Tg-eNOS/GCH double-transgenic mice vs. aged WT mice (0.83±0.07 vs. 1.91±0.07, n=3, p<0.01), with a concomitant augmentation of SIRT1 level (1.14±0.02 vs. 0.54±0.06, n=3, p<0.01). Finally, miR-34a expression was down-regulated in EPCs from Tg-GCH mice with an increase in SIRT1 level, and was up-regulated in EPCs from BH4-deficient hph-1 mice with a decrease in SIRT1 level vs. WT mice.

Conclusion:
These findings demonstrate, for the first time, that miR-34a promotes impairment of EPC angiogenesis in aging, which could be rescued by GTPCH I/BH4.
Abstract 17294: Medication Discrepancies in Heart Failure: an Independent Predictor of Hospitalizations
Authors: Small Katherine E , Prendergast Kathleen A , Shah Sanjiv
Published: April 2024

Background:
One advantage of the recent mandate by the U.S. government for electronic medical records (EMR) is the ability to reconcile medications in order to limit adverse effects of polypharmacy, thereby potentially improving outcomes. High-risk patients on multiple medications, such as those with heart failure (HF), stand to benefit greatly from the EMR. While medication discrepancies still occur in the EMR, their association with adverse outcomes in HF has not previously been examined. Hypothesis: The number of medication discrepancies in the EMR of HF patients is associated with adverse outcomes.

Methods:
We prospectively studied 99 HF patients and compared medications lists in the EMR with patient-reported medications to determine the number of medication discrepancies. We dichotomized patients into 2 groups: “Low Discrepancies” (0-1) and “High Discrepancies” (2 or greater). Multivariable linear regression was performed to determine whether increased number of medication discrepancies was independently associated with increased number of hospitalizations over a 1-year period.

Results:
Patients with increased medication discrepancies (≥ 2) were more symptomatic based on NYHA class, had a higher number of health care providers, and had more hospitalizations over a 1 year period (Table). On multivariable linear regression analysis, the number of medication discrepancies was independently associated with the number of hospitalizations (beta-coefficient 0.17, 95% CI 0.08-0.25), p<0.0001 per each medication discrepancy after adjusting for age, sex, ethnicity, NYHA class, and total number of medications.

Conclusion:
Despite the use of a well-established EMR in HF patients, medication discrepancies still exist. The number of medications discrepancies is an independent predictor of number of hospitalizations in patients with HF. Improving EMR medication reconciliation, especially in HF patients who have multiple providers, is critical.
Abstract 17306: Right Ventricular Response to Exercise in Patients with an Obstructed Right Ventricle-to-Pulmonary Artery Conduit: Effects of Transcatheter Pulmonary Valve Replacement
Authors: Hasan Babar S , Lunze Fatima I , Brown David W , Boudreau Matthew J , Chen Ming Hui , McElhinney Doff B
Published: April 2024

Background:
In patients with repaired congenital heart disease, the clinical evaluation of right ventricular outflow tract (RVOT) conduit dysfunction (i.e. stenosis or regurgitation) has classically involved analysis of anatomic and physiologic changes of the right ventricle (RV) at rest. Such evaluation does not reflect dynamic changes that occur during exercise, or elicit functional changes in response to physiologic stress. In this study, we characterized the physiologic effects of exercise on the RV in patients with an obstructed RVOT conduit before and after transcatheter pulmonary valve replacement (TPV).

Methods:
Patients with RVOT conduit obstruction who underwent TPV between March 2010- March 2011 at Children's Hospital Boston were enrolled. Exercise echocardiograms were performed in all patients. Rest and peak exercise RVOT gradient, RV systolic pressure, and 2D global longitudinal RV strain parameters (composite of 6-segment RV strain from a 4-chamber apical view via speckled tracking) were obtained prior to and 6 months post-TPV.

Results:
A total of 12 patients, of whom 8 had Tetralogy of Fallot (67%) were enrolled and completed the study. Median age at the time of TPV was 18 yrs (range 4 - 28). Prior to TPV, the median resting maximum instantaneous gradient (MIG) was 60mmHg (range 32-85) and increased with peak exercise to 95 mmHg (range 50 -156; p<0.001). At baseline, resting global RV strain was -15% (-6, 19.6) and increased to -17% (-3, -22; p =0.005) at peak exercise. Following TPV, median MIG declined significantly at rest to 21mmHg (range 16-41; p= 0.03 vs. pre-TPV) and at peak exercise, 41mmHg (range 27-81; p=0.03 vs. pre-TPV), but still with a significant increase in MIG from rest to peak exercise (p<0.001). Following TPV, global RV strain increased at rest,-17% (-2, -24; p= 0.005), and further at peak exercise, -20% (-6, -23; p=0.01).

Conclusions:
Exercise led to a significant increase in the peak RVOT gradient and global longitudinal RV strain both before and after TPV. TPV resulted in significantly improved RVOT gradient and longitudinal RV myocardial deformation both at rest and during peak exercise.
Abstract 17337: Postconditioning with Netrin-1 Protects Against Myocardial Ischemia-Reperfusion Injury Via a DCC/ERK1/2/eNOS Mechanism
Authors: Bouhidel Jalaleddinne O , Cai Hua L
Published: April 2024

Given as a pre-conditioning mimetic, we have previously shown that netrin-1 markedly reduces myocardial ischemia-reperfusion (I/R) injury by increasing nitric oxyde (NO) bioavailability. However, its potential beneficial effect remains unknown if given as a post-conditioning agent. Langendorff perfused hearts isolated from C57BL/6 wild-type (WT) mice or DCC+/- mice underwent 20-min of global ischemia followed by 60-min of reperfusion (n=6). DCC (deleted in colorectal cancer) is one of the netrin-1 receptors we found to be however specifically involved in netrin-1 pre-conditioning induced cardioprotection. Netrin-1 was infused post-conditionally at the onset of reperfusion at 100 ng/mL concentration with and without UO126, a specific MEK1/2 inhibitor or 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a NO-scavenger. In WT mice, netrin-1 postconditioning significantly reduced infarct size to 17±2.5% from 43.3±4.6% in the untreated control I/R group. This phenomenon is now further confirmed using an in vivo model of myocardial ischemic injury, 30-min coronary occlusion followed by 24-hr reperfusion. UO126 or PTIO administration alone had no effect on infarct size (respectively 44.8±3% and 39.8±1.7% vs 43.3±4.6% in the untreated control I/R group) but abolished the effects of netrin-1, implicating intermediate roles of MEK/ERK1/2 and NO (respectively 44.8±2% and 43.5±2.9% vs 17±2.5% in the netrin-1 treated I/R group). Indeed, ERK1/2 and eNOS phosphorylation was significantly upregulated by netrin-1 treatment. Interestingly, the protective effect of netrin-1 was markedly diminished in the DCC+/- mice (infarct size increased to 44.5±2% from 15±2.6 % in the DCC+/+ group), indicating a dependency on DCC of netrin-1 post-conditoning induced cardioprotection. Netrin-1 also feed-forwardly upregulated DCC protein expression. Taken together, these results strongly suggest that netrin-1 protects against I/R injury in the murine heart as a post-conditioning mimetic by increasing NO production via activation of a ERK1/2/eNOS pathway, which also involves DCC activation and upregulation. These findings demonstrate that netrin-1 can serve as an innovative and powerful agent for acute treatment of myocardial infarction.