bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 606: Antithrombin Nanoparticle Therapy Safely Restores Endothelial Barrier Integrity and Reduces Vessel Hypercoagulability in Atherosclerotic Mice
Authors: Palekar Rohun U , Jallouk Andrew P , Pan Hua , Wickline Samuel A
Published: July 2021

Introduction:
Thrombin plays a major role in regulating signaling pathways responsible for atherogenesis, hypercoagulability and plaque permeability. Herein, we report the therapeutic effects of perfluorocarbon core nanoparticles (PFC-NP) conjugated to the thrombin inhibitor D-phenylalanyl-L-prolyl-L-chloromethylketone (PPACK-NP) on vascular barrier integrity and hypercoagulability.

Methods and Results:
ApoE-/- mice were fed a Western diet for 4 months, and received 3 doses/week of saline or 1 ml/kg PPACK-NP for the final month of feeding. Endothelial barrier integrity was assessed by quantifying the ability of atherosclerotic aortas to take up circulating semipermeable PFC-NP (~250 nm diameter). Whole aortas (arch to iliacs) were excised after 2 hour in vivo exposure to PFC-NP and underwent fluorine magnetic resonance spectroscopy (
19
F-MRS) to quantify plaque-permeating PFC-NP.
19
F-MRS data revealed a significant decrease in plaque permeability to PFC-NP after PPACK-NP treatment compared to saline control (0.081 ± 0.011 μl PFC-NP/g aorta, N = 5 vs. 0.122 ± 0.014 μl PFC-NP/g aorta, N = 8 for PPACK-NP treated vs. saline control, p = 0.027). To assess hypercoagulability, carotid artery injury was induced photochemically to measure the time to complete occlusion as an index of thrombotic risk. Occlusion times were significantly prolonged with PPACK-NP treatment compared to untreated mice (49.8 ± 6.7 min, N = 5 vs. 26.1 ± 4.6 min, N = 9 for PPACK-NP treated vs. saline control, p = 0.019), indicating a
decrease
in vessel hypercoagulability after therapeutic intervention. Furthermore, PPACK-NP treatment of human aortic endothelial cells
in vitro
abrogated thrombin-mediated activation of surface PAR-1 receptors as measured by flow cytometry, suggesting a potential dual role for PPACK-NP in the localized modulation of both thrombosis and PAR-1 signaling. Moreover, this sustained therapeutic benefit is obtained without systemic anticoagulation as all clotting parameters and bleeding times are completely normalized within 60 minutes after i.v. injection.

Conclusion:
Thrombin inhibition with PPACK-NP is effective in restoring vascular barrier integrity and reducing focal thrombotic risk within a single month without incurring bleeding risk.
Abstract 608: A locus on Chromosome 6 in Diversity Outbred Mice Suggests Osteogenic Regulation of Dystrophic Cardiac Calcinosis
Authors: Elnagheeb Marwa , Smallwood Tangi , O’Connor Annalouise , Bennett Brian
Published: July 2021

Introduction:
Dystrophic cardiac calcinosis (DCC) is an age-related cardiomyopathy that involves myocardial injury, necrosis, and calcification. The genetic factors contributing to myocardial calcification are complex, and several loci for DCC have been identified. However, only 1 gene, Abcc6, has been cloned and confirmed to regulate DCC. Our current studies were designed to study the genetic architecture of DCC.

Methods and Results:
Recently, the Diversity Outbred (DO) population was developed from 8 inbred strains of mice. The DO mice are mosaics of 8 progenitor strains: C57BL6/J, A/J, NOD/ShiLtJ, NZO/HiLtJ, WSB/EiJ, CAST/EiJ, PWK/PhJ and 129S1/SvImJ. Our initial studies examined the effects of diet and genetic background on the development of DCC in the 8 progenitor strains. At 24 weeks of age, the hearts of mice from these 8 strains were collected, and a colorimetric assay was used to measure calcium levels in heart tissue. ANOVA tests indicated a significant effect (p < 0.05) of the underlying genetics on DCC.

To identify genes and pathways contributing to DCC, we next performed QTL mapping using 300 DO mice. Our QTL mapping analysis was carried out using a genetic model that incorporates reconstructed haplotypes and accounts for population structure. We identify a significant (LOD 7.10) QTL on chromosome 6 (94.7 Mb - 97.3 Mb) associated with DCC. Detailed analysis identified the CAST/EiJ and PWK/PhJ founder alleles as the greatest genetic contributors to the chromosome 6 peak. Myocardial calcification involves a highly regulated process of mineralization similar to osteogenesis, and several of the positional candidates mediate calcification, including: Fam19a4, Fam19a1, Eogt, and Arl6ip5.

Conclusions:
This data identifies genes that may regulate the mineralization underlying both DCC and osteogenesis. They may yield new therapeutic targets for DCC and serve as indicators of atherosclerosis.
Abstract 611: AP-1 and ETS Family Transcription Factors Co-localize at Enhancers in Human Aortic Endothelial Cells
Authors: Hogan Nicholas T , Romanoski Casey E , Lam Michael T , Glass Christopher K
Published: July 2021

Introduction:
Sequence-specific transcription factors bind DNA regulatory elements and play a key role in establishing cellular identity. Studies comparing macrophages to B cells have revealed that small numbers of such collaborative or lineage-determining transcription factors (LDTF) establish distinct enhancers in each cell type. These factors also allow for the binding of signal dependent transcription factors. Here we present data which suggest members of the AP-1, ETS, and STAT transcription factor families serve as collaborative transcriptional regulators in human aortic endothelial cells (HAEC).

Hypothesis:
We hypothesize that a set of AP-1 and ETS transcription factors collaborate to establish key endothelial cell enhancers.

Methods:
Working in HAEC, we measured poised and active enhancers using ChIP-seq for the epigenetic histone modifications H3K4me2 and H3K27Ac, performed motif analysis, and measured transcription factor binding for candidate factors. Knockdowns of JUN, ERG, and STAT3 followed by RNA-seq were used to evaluate altered enhancer function and gene targets of candidate factors.

Results:
Our de novo motif analysis revealed that motifs for ETS and AP-1 transcription factors are highly enriched at HAEC enhancers. ChIP-seq experiments for JUN, JUNB, ERG, and STAT3 showed between 8,000 and 55,000 intergenic peaks for each factor. Together these peaks bind 50% of poised enhancers, with a subset co-localizing at these sites. Gene ontology analysis showed that gene targets of these enhancers are involved in endothelial-specific functions. Further, knockdown of JUN, ERG, and STAT3 resulted in a twofold or greater change in expression of hundreds of HAEC transcripts.

Conclusion:
The genome-wide pattern of JUN, JUNB, ERG, and STAT3 co-localization at enhancers in HAEC suggests these factors serve as key regulators that collaboratively modulate endothelial-specific gene expression. Further investigation of candidate lineage-determining transcription factors using pro-atherogenic signals could reveal regulatory mechanisms of disease-relevant endothelial transcriptional programs.
Abstract 616: Diminished K Channel Inhibition Impairs Serotonin-Mediated Vasoconstriction in the Middle Cerebral Arteries From the Fawn Hooded Hypertensive Rat
Authors: Pabbidi Mallikarjuna R , Roman Richard
Published: July 2021

Fawn Hooded Hypertensive (FHH) rat exhibit impaired pressure-mediated myogenic response (MR) in the middle cerebral arteries (MCAs) that is associated with an increase in large conductance potassium (BK) channel function. Introgression of 2.4 Mbp region of BN (Brown Norway) chromosome 1 into FHH rats (FHH.1BN) restored MR and BK channel function. The present study assessed the hypothesis that FHH rats also exhibit impaired serotonin (5-HT)-mediated vasoconstriction due to diminished BK channel inhibition compared to FHH.1BN rats. We used pressure myography and patch-clamp to measure vessel response and K channel function respectively and Fluo 4 method to measure cytosolic calcium. Basal myogenic tone of MCAs as measured by change in diameter from 22oC to 37oC temperature was ~2.6 fold lower in FHH rats compared to FHH.1BN rats (FHH, 8.1 ± 2% and FHH.1BN, 21.7 ± 3%, n = 4; p<0.05). Vascular smooth muscle cells (VSMCs) of FHH rats have significantly more negative membrane potentials (Em) (–32 ± 1 mV; n=9) compared to FHH.1BN rats (-16 ± 2mV; n=10). 5-HT-mediated vasoconstriction was lower in MCAs isolated from FHH rats compared to FHH.1BN rats (5-HT: 1μM; FHH, 36 ± 5%; FHH.1BN rats, 58 ± 9%; n = 4; p<0.05). 5-HT-mediated BK channel inhibition was less in FHH rats (3μM 5-HT: FHH, 8 ± 3%; FHH.1BN, 39 ± 4%; n = 4; p<0.05). 5-HT did not affect VSMC membrane potential in FHH rats compared to FHH.1BN rats (delta change in Em: FHH, -2 ± 2mV; n = 4; FHH.1BN, -9 ± 1 mV; n = 5; p<0.05). 5-HT-mediated increase in calcium fluorescence (F/Fo) during plateau phase was blunted in the VSMCs isolated from FHH rats compared to FHH.1BN rats (FHH: 1 + 0.01% Vs 1.22 + 0.02% in FHH.1BN (3 rats)). Finally, inhibition of BK channel restored 5-HT-mediated vasoconstriction in MCAs of FHH rats but did not affect FHH.1BN vessels (5-HT + Paxilline; FHH, 2.6 ± 0.6 fold; FHH.1BN, 1.4 ± 0.4 fold; n = 5; p<0.05). In conclusion, mutation in the genes located in 2.4 Mbp region of FHH rats disrupts 5-HT-mediated BK channel inhibition that prevents the raise in [Ca2+]i and this may contribute to impaired 5HT-mediated vasoconstriction.
Abstract 650: Characterization of Microparticles Formed by ABCA1
Authors: Hafiane Anouar , Bielicki John K , Johansson Jan O , Genest Jacques
Published: July 2021

Microparticles (MPS) are lipoprotein-sized structures created by the ABCA1 transporter. Their biological roles in health and in disease remain unknown. Here, we study MPS released from baby hamster kidney (BHK) cells stably expressing ABCA1 and human THP-1 cells also expressing ABCA1.

Media cell culture was first collected from BHK-ABCA1 expressing cells after (45min, 2, 4, 8, and 24h) incubation. After centrifugation (4000xg for 15min and 10000xg for 30min) to remove cell debris, the supernatant was passed through a 10kDa cutoff filter and subsequently subjected to analytical FPLC. FPLC analysis shows creation of a single peak in the presence of ABCA1 but not in mock-transfected BHK cells. In a time-course study, the estimated hydrodynamic diameter remained stable (≥20nm).

After 8h incubation of BHK cell with apoA-I or an apo-E mimetic peptide, CS-6253 (1μM), ABCA1 mediated formation of MPS of similar size with a significant increase in 3[H]-FC content than those generated by ABCA1 alone, (373±23 % cpm, P<0.05) and (277±60 % cpm, P<0.05) respectively. This was associated with highly lipidated nHDL-CS-6253 compararely to nHDL-apoA-I (4535±72 % cpm, P<0.001 versus 1059±14 % cpm) respectively. This data suggests that MPS formations are an integral component of cellular cholesterol efflux. Also, MPS do not contain CS-6253 when ABCA1 cells were incubated with the peptide as confirmed by western blotting similar to MPS generated from ABCA1 cells generated by apoA-I incubation. Cholesterol is effluxed more to nHDL-CS-6253 (14±7.68, % cpm, P<0.01 than to MPS 1±0.10, % cpm, 24h; P<0.01) similar to apoA-I. Depletion of membrane cholesterol by methyl-β-cyclodextrin treatment impaired HDL genesis and decrease MPS release. Detection of flotellin-2 protein enriched in MPS in total cell lysate indicated that these MPS may be related to exosomes. MPS generation was also characterized in THP-1 cells for further molecular characterization. We conclude that MPS are formed by ABCA1 in diverse cell types and the cholesterol content is dependent on activation by apo A-I or mimetic peptides. The physiological role of MPS remains to be understood. These particles may be transporters of lipids and nucleic acids.
Abstract 652: Coronary Capillaries in Ischemic Congestive Heart Failure in Rats Exhibit Significant Morphological Disorder
Authors: Kagan Heather J , Chen Jiqiu , Backeris Peter , Turnbull Irene C , Costa Kevin D , Liang Lifan , Hajjar Roger J
Published: July 2021

In ischemic congestive heart failure (CHF), the heart is damaged and undergoes compensatory remodeling, a pathological process associated with harmful effects. The goal of this study is to explore the manifestation of CHF by examining the morphological changes occurring in the coronary microvasculature in CHF versus normal rat hearts. We tested the hypothesis that coronary capillaries in rats with CHF exhibit significantly more morphological disorder than those in control rats. Methods: CHF was induced by aortic banding, ischemia/reperfusion injury two months post-banding (left coronary artery ligation for 30 minutes) and aortic debanding one month post-injury. Resin polymer containing fluorescent dye was injected into coronary vasculature of excised hearts. Muscle tissue was digested using NaOH to reveal vascular casts that were sputter coated with gold for imaging under a Scanning Electron Microscope (SEM). A total of 93 SEM images from 14 rats (7 control, 7 CHF) were analyzed for structural alignment using an automated gradient detection algorithm and circular statistics implemented using MATLAB software; Mean Vector Length (MVL) was calculated for each image as a measure of capillary organization (0<MVL<0. MVL->1 perfect alignment, MVL->0 random disarray). Results: CHF capillaries exhibit significantly more structural disorder than control (MVL 0.35±0.02 for 61 CHF, 0.58±0.02 for 32 control. p<0.01). Conclusions: Coronary capillaries in CHF rats exhibit significant abnormal morphological disarray that may impair blood flow hemodynamics and material and oxygen exchange in myocytes. Such disordered capillary remodeling could have detrimental consequences for the progression and prognosis of heart failure.
Abstract 672: Histopathological Comparison of Ascending Aortic Aneurysm: Bicuspid versus Tricuspid Aortic Valve Patients
Authors: Osada Hiroaki , Meshii Katsuaki , Ohnaka Motoaki , Kanemitsu Naoki , Nakajima Hiroyuki , Kyogoku Masahisa
Published: July 2021

Introduction:
The pathogenic mechanisms of ascending aortic aneurysm are not fully understood. The aim of this study was to identify the beginning of aortic wall dilatation based on histopathological evaluation by comparison of patients with bicuspid versus tricuspid aortic valves.

Methods:
Twenty-one patients (9 males, 12 females; mean age, 69±8.9 years) who underwent ascending aortic repair from 2008 to 2014 were divided into bicuspid aortic valve (n=8, Group B) and tricuspid aortic valve (n=13, Group T) subgroups. We compared the histopathological characteristics of the ascending aortic wall in these patients.

Results:
There were no significant differences between the two groups in age, sex, history of hypertension, and maximum diameter of the ascending aorta (Group B: 51.4±5.1 mm; Group T: 55.5±8.8 mm; p=0.247) at the time of operation. While all Group B cases exhibited aortic stenosis, there was only one case in Group T. Sclerosis or hypertrophy of the vasa vasorum was evident in both groups (Group B: 7 patients, 87.5%; Group T: 10 patients, 76.9%; p=1.000). Group B patients exhibited a much thinner aortic wall, resulting from frail smooth muscle cells of media, which induced a fragile thinner elastic lamina. The histopathological pattern of Group T was variable and included atheroma, inflammatory granulation tissue and a Marfan-like acid mucopolysaccharide pool, which produce severe fragmentation of elastic lamina.

Conclusions:
Degeneration of the vasa vasorum, which induces chronic ischemia or malnutrition of the aortic wall, is an important emerging substrate for the development of ascending aortic aneurysm. Bicuspid aortic valve patients exhibited congenital maldevelopment of the medial smooth muscle cells and elastic lamina. Tricuspid aortic valve patients exhibited severe fragmentation of elastic lamina, which induced by pathological changes including atheroma, inflammatory granuloma, and a Marfan-like acid mucopolysaccharide pool.
Abstract 678: Thoracic Aortic Dissection in Hypertensive Myh11r247c Mice Is Regulated by Gsk3β Signaling Pathway.
Authors: Wang Shanzhi , Milewicz Dianna
Published: July 2021

Acute ascending aortic dissections cause premature deaths due to pericardial tamponade. Mutations in the gene for smooth muscle specific myosin heavy chain (MYH11) causes aortic dissections with minimal aortic dilation, whereas mutations in fibrillin-1 (FBN1) causing Marfan syndrome is characterized by aneurysm formation before dissections occur. We hypothesize that distinct pathways might be responsible for the aortic dissections. Results: Mice with a homozygous Myh11 missense variant (R247C), Myh11R247C, do not have aortic enlargement and do not die prematurely of aortic dissections. Increased blood pressure induced by high salt diet and L-NAME in the Myh11R247C mice leads to sudden death that occur within 2 weeks due to acute aortic dissection and pericardial tamponade in more than 20% (9/39) of the animals (P=0.02, comparing to the death rate (1/45) in WT mice). Increased SMC proliferation and accumulation of proteoglycans are observed in the aortas of the hypertensive Myh11R247C mice. RNA Seq analysis of the Myh11R247C aortas with and without hypertension indicated targets of the Wnt pathway were increased and pathway analysis with DAVID Bioinformatics Resources identified the focal adhesion pathway was highly involved (P<0.01). Immunoblot analysis of aortic lysates confirmed increased activation of FAK and AKT, along with phosphorylation (inactivation) of GSK3β when hypertension was induced. To further inhibit GSK3β in the hypertensive Myh11R247C, the GSK3β inhibitor SB216763 was given immediately before and with hypertension induction. The death rates in Myh11R247C mutant mice but not in WT mice increased to 50% from 20% (P=0.02, N=22). Conclusion: FAK/AKT/GSK3β signaling pathway probably plays a pivotal role in acute aortic dissections in hypertensive Myh11R247C mutant mice. The SMC proliferation and proteoglycan accumulation could be important cellular pathological changes responsible for aortic dissections.
Abstract 719: PFKFB3 Mediated Glycolysis in Vascular Smooth Muscle Cells Is Essential for Arterial Neointima Formation
Authors: Wang Yong , Xu Yiming , Yan Siyuan , Liu Zhiping , Zhou Yaqi , Zeng Xianqiu , Huo Yuqing
Published: July 2021

Background:
Mature vascular smooth muscle cells (VSMCs) exhibit limited proliferation and migration ability. However, in response to stresses, VSMCs undergo phenotypic modulation characterized by increased proliferation and motility. This phenotypic modulation is associated with several vascular diseases, including atherosclerosis, arterial neointima formation. Elevated glycolysis has been described in proliferative VSMCs. The isoform 3 of 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase (PFKFB3) is a regulatory factor for VSMC glycolysis. PFKFB3 catalyze the synthesis of fructose 2, 6-bishosphate (F2, 6 BP). The latter is a powerful activator of 6-phosphofructo-1-kinase, the rate-limiting enzyme in glycolytic flux. It is unclear whether PFKFB3 mediated glycolysis play a role in VSMC phenotypic modulation andarterial neointima formation.

Methods and results:
PDGF treatment increased PFKFB3 expression in human aortic smooth muscle cells (HASMCs). This was accompanied with enhanced proliferation and migration of HASMCs. Knockdown of PFKFB3 with adenovirus carrying PFKFB3 short hairpin RNA suppressed PDGF-induced HASMC proliferation and migration. Examination of intracellular signaling indicated PI3K/Akt participated into PFKFB3-mediated glycolysis, and further cooperated with PFKFB3 to modulate phenotype of HASMCs. In a model of the left common carotid artery ligation, both PFKFB3 heterozygotes and mice with deficiency of PFKFB3 in VSMCs showed the decreased arterial neointima compared with controls mice.

Conclusions:
PFKFB3 mediates glycolysis and cooperates with PI3K/AKT, thereafter promoting proliferation and migration of VSMCs and leading to the formation of an increased arterial neointima. Thus, PFKFB3 is a promising therapeutic target for the treatment of atherosclerosis, arterial neointima and other peripheral arterial diseases.
Developmental Outcome After Surgical Versus Interventional Closure of Secundum Atrial Septal Defect in Children
Authors: Visconti Karen J. , Bichell David P. , Jonas Richard A. , Newburger Jane W. , Bellinger David C.
Published: July 2021

Background
—The assessment of the impact of cardiopulmonary bypass (CPB) on developmental outcomes in children who undergo open heart surgery is hampered by the absence of a suitable comparison group. The development of interventional catheterization techniques for the repair of certain types of congenital heart lesions provides the opportunity to study children who have not been exposed to CPB.

Methods and Results
—We performed standardized neuropsychological testing on children after closure of a secundum atrial septal defect through the use of surgery (n=26) or a transcatheter device (n=19). Device patients, compared with surgical patients, were similar in age at defect closure (mean, 6 years) but older at follow-up testing (12.3 versus 10.6 years). The mean weight percentile at closure was greater and the defect size was smaller in the device patients. Families of device patients tended to have a higher parent IQ, higher level of maternal education, and higher level of maternal occupation. In general, however, children’s IQ and achievement scores were in the normal range for both groups. In regression analyses with adjustment for age at testing and parent IQ, surgical repair was associated with a 9.5-point deficit in Full-Scale IQ (
P
=0.03) and a 9.7-point deficit in Performance IQ (
P
=0.05). Block Design was the IQ subtest on which treatment groups differed the most (
P
=0.01). Surgical patients achieved significantly better scores on errors of commission (
P
=0.05) and attentiveness index (
P
=0.03) on a continuous performance test of attention. Scores on tests of achievement and other neuropsychological domains did not differ significantly between the groups. Regression analyses within the surgical group failed to identify significant CPB-related risk factors.

Conclusions
—A prospective randomized trial or a study that includes prerepair and postrepair assessments is necessary to establish whether the observed advantages of device closure in neuropsychological outcome represent deleterious effects of CPB or a methodological artifact.
Early Survival of Infants Weighing 2.5 Kilograms or Less Undergoing First-Stage Reconstruction for Hypoplastic Left Heart Syndrome
Authors: Weinstein Samuel , Gaynor J. William , Bridges Nancy D. , Wernovsky Gil , Montenegro Lisa M. , Godinez Rodolfo I. , Spray Thomas L.
Published: July 2021

Background
—Results of staged palliation for hypoplastic left heart syndrome (HLHS) have improved in recent years; however, certain risk factors have been associated with decreased survival rates.

Methods and Results
—We retrospectively reviewed the medical records of 67 patients weighing ≤2.5 kg undergoing the first stage of reconstructive surgery at our institution between January 1, 1990, and December 31, 1997. HLHS was present in 45 patients, complex double-outlet right ventricle in 10, unbalanced AV canal in 5, tricuspid atresia with transposition of the great vessels in 4, and other diagnoses in 3. Mean age at surgery was 10.1±10.7 days (median, 8 days), and mean weight was 2.2±0.3 kg (median, 2.2 kg). Fourteen patients weighed ≤2.0 kg, and 2 patients weighed ≤1.5 kg. Early mortality (death within 30 days or before hospital discharge) was 51% (34 of 67). No patient, procedural, or time-related variables correlated with increased mortality. However, there was a trend toward increased mortality with increased cardiopulmonary bypass time (
P
=0.076) and decreased preoperative ventricular performance (
P
=0.139).

Conclusions
—These findings suggest that low weight alone in a patient with HLHS or an anatomic variant should not be considered a contraindication to staged reconstructive surgery.
Aortic Valve Replacement With the Freestyle Stentless Bioprosthesis
Authors: Yun Kwok L. , Sintek Colleen F. , Fletcher Alden D. , Pfeffer Thomas A. , Kochamba Gary S. , Hyde Manly R. , Torpoco Jesus O. , Khonsari Siavosh
Published: July 2021

Background
—Stentless aortic valves were designed to provide a more physiological flow pattern and lower transvalvular gradient, which may have an important bearing on postoperative left ventricular function and remodeling. In this study, we prospectively analyzed the 5-year clinical results with the Freestyle valve (Medtronic, Inc) and its hemodynamic performance by serial echocardiography.

Methods and Results
—Between January 1993 and August 1997, 95 patients with a mean age of 75 years underwent aortic valve replacement with the Freestyle prosthesis. Sixty-four percent of patients received valves ≤23 mm, and 37% had concomitant coronary artery bypass grafting. Average follow-up was 44±18 months (mean±SD), and echocardiography was performed preoperatively, at discharge, at 3 to 6 months, and annually thereafter. The 30-day operative mortality rate was 3%, with an overall actuarial survival rate of 80±6% (mean±SEM) at 5 years. Of the 10 late deaths, only 2 were cardiac related, thereby yielding a freedom from cardiac mortality of 94±3% after 5 years. No patient required reoperation on the aortic valve for any reason, including structural degeneration, nonstructural dysfunction, or prosthetic valve endocarditis. There were 9 thromboembolic and 3 anticoagulant-related bleeding events, none of which was fatal. The actuarial freedom from valve-related morbidity and mortality was 79±4% at 5 years. Hemodynamically, the mean transvalvular gradient significantly decreased after valve replacement and was reduced further by 41% by 6 months with a corresponding increase in effective orifice area. Left ventricular mass index fell to 75% of the preoperative value by 2 years.

Conclusions
—The Freestyle stentless valve can be implanted safely in the elderly with excellent midterm clinical results. It has superb hemodynamics in terms of residual transvalvular gradient, effective orifice area, and regression of left ventricular hypertrophy.
Intravenous Immunoglobulin Reduces Anti-HLA Alloreactivity and Shortens Waiting Time to Cardiac Transplantation in Highly Sensitized Left Ventricular Assist Device Recipients
Authors: John Ranjit , Lietz Katherine , Burke Elizabeth , Ankersmit Jan , Mancini Donna , Suciu-Foca Nicole , Edwards Niloo , Rose Eric , Oz Mehmet , Itescu Silviu
Published: July 2021

Background
—Recipients of left ventricular assist devices (LVADs) develop prominent B-cell hyperreactivity. We investigated the influence of anti-HLA antibodies on waiting time to cardiac transplantation in LVAD recipients and compared the effects of 2 immunomodulatory regimens on anti-HLA serum reactivity.

Methods and Results
—Fifty-five previously nonsensitized LVAD recipients of a TCI device implanted between 1990 and 1996 were studied. Patients with anti-HLA antibodies received monthly courses of either intravenous immunoglobulin (IVIg) or plasmapheresis, in conjunction with cyclophosphamide. The effects of these regimens on anti-HLA alloreactivity and waiting time to transplantation were then determined by Kaplan-Meier log-rank statistics, nonparametric Wilcoxon rank-sum test, and Student’s
t
test. Prolongation in transplant waiting time was related to serum IgG anti–HLA class I alloreactivity. Infusion of IVIg (2 g/kg) caused a mean reduction of 33% in anti–HLA class I alloreactivity within 1 week. Waiting time to transplantation was significantly reduced by IVIg therapy and subsequently approximated that in nonsensitized patients. Side effects of IVIg (2 g/kg) were minimal and related primarily to immune complex disease. Although plasmapheresis caused a similar reduction in alloreactivity to IVIg, this effect was achieved after longer treatment. Moreover, plasmapheresis was associated with an unacceptably high frequency of infectious complications. In patients resistant to low-dose (2 g/kg) IVIg therapy, high-dose (3 g/kg) IVIg was effective in reducing alloreactivity but was associated with a high incidence of reversible renal insufficiency.

Conclusions
—These results indicate that IVIg is an effective and safe modality for sensitized recipients awaiting cardiac transplantation, reducing serum anti-HLA alloreactivity and shortening the duration to transplantation. The therapeutic and safety profile of IVIg would appear to be superior to plasmapheresis.
Early and Long-Term Results of a Valve-Sparing Operation for Marfan Syndrome
Authors: Birks Emma J. , Webb Carole , Child Anne , Radley-Smith Rosemary , Yacoub Magdi H.
Published: July 2021

Background
—We have previously described the experience, rationale, and development of a valve preserving technique, but its role in patients with Marfan syndrome has not previously been defined. Here, we attempt to determine the early and long-term results, timing, and determinants of outcome of this operation in patients with Marfan syndrome.

Methods and Results
—Since 1979, 82 patients (73.2% of all patients with Marfan syndrome undergoing resection of aneurysm of the ascending aorta) were operated on using this technique. Ages ranged from 2 to 69 years (mean, 33.9 years). In all, there were 4 early deaths (4.9%), 2 with acute dissection and 2 with chronic aneurysm operated on as emergencies. There were no early deaths in 67 patients operated on electively. Actuarial survival for patients operated for chronic aneurysm was 94.2%, 94.2%, and 94.2% at 1, 5, and 10 years, respectively; that for acute dissection was 72.7%, 63.6%, and 63.6%; and that for chronic dissection was 100%, 85.7%, and 75.0%. The probability of needing reoperation was 5.7%, 17.3%, and 17.3% at 1, 5, and 10 years. There were no instances of infective endocarditis or thromboembolic complications except in 2 patients operated on early in the series who had cusp extension. At the end of the follow-up, trivial or no aortic regurgitation was demonstrated in 33.3%, mild in 45.6%, moderate in 21.1%, and severe in 0.

Conclusions
—Valve-sparing operations are feasible in most patients with Marfan syndrome; they are applicable to patients with both dissection and chronic aneurysm. The early and long-term results are encouraging. Results are better in the absence of dissection, and prophylactic operation is warranted in some cases.
Evidence for Preconditioning by Isoflurane in Coronary Artery Bypass Graft Surgery
Authors: Belhomme Denis , Peynet Jacqueline , Louzy Moez , Launay Jean-Marie , Kitakaze Masafumi , Menasché Philippe
Published: July 2021

Background
—Experimentally, isoflurane, a commonly used volatile anesthetic agent, mimics the cardioprotective effects of ischemic preconditioning via a mechanism that could involve the activation of protein kinase C. The present study was designed to assess the clinical relevance of this observation in patients undergoing elective CABG.

Methods and Results
—Twenty patients were included in the study. In 10 of them, preconditioning was elicited after the onset of cardiopulmonary bypass via a 5-minute exposure to isoflurane (2.5 minimum alveolar concentration), followed by a 10-minute washout before aortic cross-clamping and cardioplegic arrest. Ten case-matched control patients underwent an equivalent period (15 minutes) of prearrest isoflurane-free bypass. Outcome measurements included troponin I and creatine kinase–MB isoenzyme (until the third postoperative day) levels and the activity of ecto-5′-nucleotidase, which contributes to adenosine production and is considered to be a reporter of protein kinase C activation, as assessed in right atrial biopsy samples taken before bypass and at the end of the preconditioning protocol (or after 15 minutes of bypass in control patients). Aortic cross-clamping times did not differ between the 2 groups: 52±14 and 48±14 minutes (mean±SD) in control and isoflurane-preconditioned patients, respectively. Likewise, prebypass values of ecto-5′-nucleotidase were similar in control (3.54±0.86 nmol · mg protein
−1
· min
−1
) and isoflurane-treated (2.98±1.08 nmol · mg protein
−1
· min
−1
) patients. The values subsequently remained unchanged in control patients (3.62±0.94 nmol · mg protein
−1
· min
−1
), whereas they significantly increased after isoflurane preconditioning (4.74±0.50 nmol · mg protein
−1
· min
−1
;
P
<0.002 versus baseline values,
P
<0.004 versus time-matched values in control patients). This was paralleled by a consistently smaller release of troponin I, which yielded an area under the curve and a peak value of 204±147 ng · mL
−1
· min
−1
and 3.98±2.83 ng/mL, respectively, versus 284±136 ng · mL
−1
· min
−1
and 5.88±3.64 ng/mL, respectively, in control patients. The release of creatine kinase–MB featured a similar pattern. There were no adverse effects related to isoflurane.

Conclusions
—These data support a cardioprotective effect of isoflurane and, more generally, demonstrate the feasibility of pharmacologically preconditioning the human heart during cardiac surgery.
Opiate Drugs and δ-Receptor–Mediated Myocardial Protection
Authors: Benedict Patrick E. , Benedict Mary B. , Su Tsung-Ping , Bolling Steven F.
Published: July 2021

Background
—Hypothermic myocardial arrest is necessary to complete most cardiac surgery, which limits the success of such operations. Similarly, cold, inhospitable environments limit the survival of warm-blooded animals. Animals have successfully adapted to this challenge through hibernation. Hibernation is an energy-conserving state, now known to be governed by cyclical variation in endogenous opiate compounds. It may also be induced in nonhibernators via hibernating animal serum factors or δ-opiate peptides. Furthermore, hibernation-induction triggers extend organ preservation in many models. This study examined whether opiate drugs with an affinity for the δ-opiate receptor confer similar protection.

Methods and Results
—Isolated hearts harvested from New Zealand White rabbits were treated with either cardioplegia alone or δ-opiate drugs (fentanyl, morphine, buprenorphine, pentazocine) followed by 2 hours of 34°C ischemia. Hearts were then reperfused, and functional and metabolic indices of treated groups were compared with untreated controls. Isovolumic developed pressure, coronary flow, and oxygen consumption were compared as a percent of preischemia versus 45 minutes after reflow. Developed pressure and oxygen consumption were better preserved in the morphine, buprenorphine, and pentazocine groups when compared with cardioplegia alone.

Conclusions
—Drugs with δ-opiate activity confer myocardial protection, which is additive to cardioplegia. Use of δ-opiate drugs in this context may have important clinical implications.
Ischemic Preconditioning Reduces Apoptosis By Upregulating Anti-Death Gene Bcl-2
Authors: Maulik Nilanjana , Engelman Richard M. , Rousou John A. , Flack Joseph E. , Deaton David , Das Dipak K.
Published: July 2021

Background
—Reperfusion of ischemic myocardium causes cardiomyocyte apoptosis in concert with downregulation of Bcl-2 gene. Ischemic preconditioning (PC) mediated by cyclic episodes of short-term ischemia and reperfusion reduces apoptotic cell death. PC also triggers a signaling pathway by potentiating tyrosine kinase phosphorylation leading to the activation of p38 MAP kinase and MAPKAP kinase 2. The nuclear transcription factor, NFκB, plays a crucial role in this signaling process. Because NFκB is a target of oxygen free radicals and Bcl-2 is an antioxidant gene, we hypothesized that reactive oxygen species might play a role in the signaling process.

Methods and Results
—Isolated rat hearts were perfused in the absence or presence of either dimethyl thiourea (DMTU), a hydroxyl radical scavenger, or SN50 peptide, a NFκB blocker. Hearts were then subjected to PC by 4 repeated episodes of 5-minute ischemia, each followed by 10 minutes reperfusion. All hearts were then made globally ischemic at normothermia for 30 minutes followed by 2 hours of normothermic reperfusion. Creatine kinase release and malonaldehyde formation were determined in the coronary effluent collected during reperfusion. At the end of each experiment, hearts were processed for infarct size determination and analyses of apoptosis, DNA fragmentation, NFκB, and Bcl-2. Myocardial infarction was reduced by PC. DMTU and SN50 abolished this cardioprotective effect of PC. PC resulted upregulation of Bcl-2 gene which was partially prevented by DMTU and SN50. Both ischemia/reperfusion and PC caused nuclear translocation and activation of NFκB, which was blocked by both DMTU and SN50. PC reduced cardiomyocyte apoptosis which was partially inhibited by DMTU and SN50. A substantial number of apoptotic cardiomyocytes were identified in the hearts subjected to 30 minutes ischemia and 2-hour reperfusion. PC significantly inhibited the extent of cardiomyocyte apoptosis and DMTU and SN50 reversed it only minimally.

Conclusions
—The results demonstrate that reactive oxygen species play a crucial role in signal transduction mediated by PC. This signaling process appears to involve NFκB. NFκB becomes translocated and activated by both ischemia/reperfusion, which induces apoptosis and PC which reduces apoptosis. However, the amount of NFκB binding activity is significantly higher in the PC hearts compared with ischemic reperfused hearts. The upregulation of the antioxidant gene, Bcl-2, is inversely correlated with the reduction of cardiomyocyte apoptosis associated with PC.
Adenosine-Supplemented Blood Cardioplegia Attenuates Postischemic Dysfunction After Severe Regional Ischemia
Authors: Thourani Vinod H. , Ronson Russell S. , Van Wylen David G.L. , Shearer Steven T. , Katzmark Sara L. , Zhao Zhi-Qing , Han David C. , Guyton Robert A. , Vinten-Johansen Jakob
Published: July 2021

Background
—Various studies have reported that the administration of adenosine (ADO) in cardioplegia reduces myocardial ischemic injury, but this timing may not utilize ADO’s potential against myocardial reperfusion injury. This study tested the hypothesis that ADO-supplemented blood cardioplegia (BCP) or ADO administered during reperfusion reduces postischemic dysfunction after severe regional ischemia.

Methods and Results
—After 75 minutes of left anterior descending coronary artery occlusion, total cardiopulmonary bypass was initiated; cold (4°C) antegrade BCP (8:1 blood:crystalloid) was delivered every 20 minutes for the first 3 doses, and 27°C BCP was delivered for the terminal infusion. Dogs (n=6 per group) received unsupplemented BCP, ADO (100 μmol/L/L) supplemented in all infusions of BCP (ADO-CP), or ADO (100 μmol · L
−1
· L
−1
) supplemented only in the terminal infusion of BCP followed by intravenous ADO (140 μg · kg
−1
· min
−1
) infusion for the first 30 minutes of reperfusion (ADO-R). Postischemic regional systolic shortening was significantly greater in the ADO-R group (5±2.0%) than in the BCP group (−3±1.0%), but not in the ADO-CP group (2±0.2%). Postischemic regional diastolic stiffness in the area at risk during end reperfusion was lower with ADO-R (1.8±0.3%) than with ADO-CP (2.7±0.3%) or BCP (4.4±0.5%). Infarct size was reduced in the ADO-CP (29±2%) and ADO-R (21±2%) groups compared with the BCP group (42±4%). Edema in the myocardial area at risk was decreased in the ADO-CP (82±0.2%) and ADO-R (80±0.4%) groups compared with the BCP group (86±0.7%). Adherence of fluorescently labeled neutrophils (PMNs) to postischemic coronary artery endothelium was attenuated by ADO-R (55±2 PMNs/mm
2
), but not by ADO-CP (114±5 PMNs/mm
2
), compared with BCP (118±3 PMNs/mm
2
).

Conclusions
—The results show that BCP supplemented with ADO reduces infarct size, preserves postischemic systolic and diastolic regional function but does not attenuate coronary artery endothelial dysfunction unless administered during reperfusion.
Survival and Function of Bioengineered Cardiac Grafts
Authors: Li Ren-Ke , Jia Zhi-Qiang , Weisel Richard D. , Mickle Donald A. G. , Choi Angel , Yau Terrence M.
Published: July 2021

Introduction
—Patients with congenital heart disease frequently require graft material for repair of cardiac defects. However, currently available grafts lack growth potential and are noncontractile and thrombogenic. We have developed a viable cardiac graft that contracts spontaneously in tissue culture by seeding cells derived from fetal rat ventricular muscle into a biodegradable material. We report our investigations of the in vitro and in vivo survival and function of this bioengineered cardiac graft.

Methods and Results
—A cardiomyocyte-enriched cell inoculum derived from fetal rat ventricular muscle was seeded into a piece of Gelfoam (Upjohn, Ontario, Canada), a biodegradable gelatin mesh, to form the graft. For in vitro studies, growth patterns of the cells within the graft were evaluated by constructing growth curves and by histologic examination; in in vivo studies, the graft was cultured for 7 days and then implanted either into the subcutaneous tissue of adult rat legs or onto myocardial scar tissue in a cryoinjured rat heart. Five weeks later, the graft was studied histologically. The inoculated cells attached to the gelatin mesh and grew in 3 dimensions in tissue culture, forming a beating cardiac graft. In both the subcutaneous tissue and the myocardial scar, blood vessels grew into the graft from the surrounding tissue. The graft implanted into the subcutaneous tissue contracted regularly and spontaneously. When implanted onto myocardial scar tissue, the cells within the graft survived and formed junctions with the recipient heart cells.

Conclusions
—Fetal rat ventricular cells can grow 3-dimensionally in a gelatin mesh. The cells in the graft formed cardiac tissue and survived and contracted spontaneously both in tissue culture and after subcutaneous implantation. Future versions of this bioengineered cardiac graft may eventually be used to repair cardiac defects.
Mitral Valve Replacement or Repair After Previous Coronary Artery Bypass Grafting
Authors: Izhar Uzi , Daly Richard C. , Dearani Joseph A. , Orszulak Thomas A. , Schaff Hartzell V. , Mullany Charles J.
Published: July 2021

Background
—Patients who have had previous CABG may subsequently develop significant mitral valve (MV) dysfunction that requires surgical intervention.

Methods and Results
—We reviewed 80 consecutive patients who had had previous CABG and who underwent MV surgery between January 1972 and March 1997. Forty-seven (59%) had initial CABG elsewhere, and 5 had had previous CABG twice. The mean interval between the previous CABG and the MV surgery was 6.3 years (range, 4.4 months to −17 years). At least 15 patients had grade 1/4 to 2/4 mitral regurgitation at initial CABG. The study group included 59 men and 21 women, with a mean study group age of 65.5 years. Ninety-four percent had symptoms of congestive heart failure, 60% had angina, 96% were in NYHA class III to IV, and 37% had an ejection fraction (EF) <50%. Origin of the MV disease was ischemic in 33 patients, myxomatous in 19, combined ischemic and myxomatous in 16, rheumatic in 5, infective in 3, and unknown in 4. MV repair was performed in 46 patients (58%) and MV replacement (MVR) in 34. Concomitant repeat CABG was performed in 38 (48%) patients. In-hospital mortality was 7 of 80 (8.8%); no early death occurred among patients with myxomatous disease. EF <50% was the only significant predictor of early mortality. Overall 1-, 5-, and 10-year survival was 83.8%, 55.6%, and 34.4% respectively. Predictors of late cardiac death were preoperative NYHA class IV (
P
=0.0006), urgent or emergency operation (
P
<0.0001), use of intra-aortic balloon pump (
P
=0.002), and EF <50% (
P
=0.01). Seven patients had an additional reoperation: 4 received CABG, 2 MVR, and 2 MV repair.

Conclusions
—Ischemic, myxomatous, rheumatic, or infective MV dysfunction may develop subsequently after CABG. MVR or MV repair after previous CABG is associated with an acceptably low operative risk and good relief of symptoms. Left ventricular function is strongly correlated with both hospital and late mortality. Surgery should be done before LV dysfunction develops.
Prospectively Randomized Comparison of Different Mechanical Aortic Valves
Authors: Autschbach Rüdiger , Walther Thomas , Falk Volkmar , Kostelka Martin , Rösler Annegret , Langebartels Georg , Krüger Martin , Diegeler Anno , Mohr Friedrich W.
Published: July 2021

Background
—The aim of this prospectively randomized study was to evaluate the hemodynamic and functional outcomes after aortic valve replacement with 3 different bileaflet mechanical valves.

Methods and Results
—Three hundred consecutive patients were randomly assigned to receive ATS (n=100), Carbomedics (n=100), or St Jude Medical Hemodynamic Plus (n=100) mechanical aortic valve replacement. There were no significant differences regarding patient age (average 61±8 years), body surface area (1.9±0.2 m
2
), left ventricular function (ejection fraction 0.59±0.17), and presence of aortic stenosis (90%, 89%, and 91%), respectively. All patients had postoperative as well as 6-month and 1-year follow-ups that included transthoracic echocardiography. Multivariate statistical analysis was performed. Implanted valve sizes were comparable at 24±2 (ATS), 23.7±1.6 (CM), and 23.6±1.9 (SJM
HP
) mm (NS). At 1-year follow-up, the following incidence of events was noted: death 3/1/1, all non–valve related; stroke 0/1/1; trivial transvalvular incompetence 3/3/2; paravalvular leak 2/3/2; and reoperation 0/1/1, respectively (NS). Transvalvular flow velocities were 2.5/2.6/2.4 m/s postoperatively (
P
=0.03) and 2.4/2.4/2.3 m/s at 6-month follow-up, respectively (NS). There was a significant decrease in left ventricular mass for all patients but no significant differences among the groups.

Conclusions
—There are no clinically relevant differences among the tested bileaflet aortic valves. Regardless of valve type, there was a low complication rate. On the basis of these findings, all 3 bileaflet prostheses are well suited for aortic valve replacement.
Factors Affecting Longevity of Homograft Valves Used in Right Ventricular Outflow Tract Reconstruction for Congenital Heart Disease
Authors: Tweddell James S. , Pelech Andrew N. , Frommelt Peter C. , Mussatto Kathleen A. , Wyman John D. , Fedderly Raymond T. , Berger Stuart , Frommelt Michele A. , Lewis David A. , Friedberg David Z. , Thomas John P. , Sachdeva Ramesh , Litwin S. Bert
Published: July 2021

Background
—Few studies have explored the long-term function of cryopreserved homograft valves used for reconstruction of the right ventricular tract (RVOT) in patients with congenital heart disease.

Methods and Results
—Among 205 patients receiving cryopreserved homografts for reconstruction of the RVOT between November 1985 and April 1999, the outcome of 220 homografts in 183 operative survivors was analyzed. There were 150 pulmonary and 70 aortic homografts used. Median age at implantation was 4.4 years (mean 6.9±7.6 years, range 3 days to 48 years). End points included (1) patient survival, (2) homograft failure (valve explant or late death), and (3) homograft dysfunction (homograft insufficiency or homograft stenosis). Survival was 88% at 10 years. Freedom from homograft failure was 74±4% at 5 years and 54±7% at 10 years. Univariable analysis identified younger age, longer donor warm ischemic time, valve
Z
value <2, and previous procedure as risk factors for homograft failure and dysfunction. Aortic homograft type and extracardiac operative technique predicted homograft failure but not dysfunction. For patients ≤1 year of age, valve type did not predict failure or dysfunction. Multivariable analysis identified younger age and longer donor warm ischemic time as risk factors for homograft failure and dysfunction, whereas,
Z
value <2 and aortic valve type predicted homograft valve failure.

Conclusions
—Homograft valves used for RVOT reconstruction provide effective intermediate palliation with excellent late survival. Factors that adversely affect graft longevity include younger age, longer donor warm ischemic time, smaller homograft size, use of aortic homograft in the older patient, and extracardiac operative technique.