Genetic deletion or pharmacologic inhibition of HDAC6 protects the heart against ischemia/reperfusion injury by limiting TNFα-induced mitochondrial injury in experimental diabetes.

AIMS: The histone deacetylase 6 (HDAC6) inhibitor, tubastatin A, reduces myocardial ischemia/reperfusion injury (MIRI) in type 1 diabetic rats. It remains unclear whether HDAC6 regulates MIRI in type 2 diabetic animals. Diabetes augments activity of HDAC6 and generation of tumor necrosis factor α (TNFα) and impairs mitochondrial complex I (mCI). Here we examined how HDAC6 regulates TNFα production, mCI activity, mitochondria, and cardiac function in type 1 and type 2 diabetic mice undergoing MIRI. METHODS AND RESULTS: HDAC6 knockout, streptozotocin-induced type 1 diabetic, and obese type 2 diabetic db/db mice underwent MIRI in vivo or ex vivo in a Langendorff-perfused system. We found that MIRI and diabetes additively augmented myocardial HDAC6 activity and generation of TNFα, along with cardiac mitochondrial fission, low bioactivity of mCI, and low production of ATP. Importantly, genetic disruption of HDAC6 or tubastatin A decreased TNFα levels, mitochondrial fission, and myocardial mitochondrial NADH levels in ischemic/reperfused diabetic mice, concomitant with augmented mCI activity, decreased infarct size, and improved cardiac function. Moreover, HDAC6 knockout or tubastatin A treatment decreased left ventricular dilation and improved cardiac systolic function 28 days after MIRI. H9c2 cardiomyocytes with and without HDAC6 knockdown were subjected to hypoxia/reoxygenation injury in the presence of high glucose. Hypoxia/reoxygenation augmented HDAC6 activity and TNFα levels and decreased mCI activity. These negative effects were blocked by HDAC6 knockdown. CONCLUSIONS: HDAC6 is an essential negative regulator of MIRI in diabetes. Genetic deletion or pharmacologic inhibition of HDAC6 protects the heart from MIRI by limiting TNFα-induced mitochondrial injury in experimental diabetes.

Partial heart xenotransplantation: A research protocol in non-human primates.

Partial heart transplantation is a new type of transplant that delivers growing heart valve replacements for babies. Partial heart transplantation differs from orthotopic heart transplantation because only the part of the heart containing the heart valve is transplanted. It also differs from homograft valve replacement because viability of the graft is preserved by tissue matching, minimizing donor ischemia times, and recipient immunosuppression. This preserves partial heart transplant viability and allows the grafts to fulfill biological functions such as growth and self-repair. These advantages over conventional heart valve prostheses are balanced by similar disadvantages as other organ transplants, most importantly limitations in donor graft availability. Prodigious progress in xenotransplantation promises to solve this problem by providing an unlimited source of donor grafts. In order to study partial heart xenotransplantation, a suitable large animal model is important. Here we describe our research protocol for partial heart xenotransplantation in nonhuman primates.

Augmentation of Histone Deacetylase 6 Activity Impairs Mitochondrial Respiratory Complex I in Ischemic/Reperfused Diabetic Hearts.

BACKGROUND: Diabetes augments activity of histone deacetylase 6 (HDAC6) and generation of tumor necrosis factor α (TNFα) and impairs the physiological function of mitochondrial complex I (mCI) which oxidizes reduced nicotinamide adenine dinucleotide (NADH) to nicotinamide adenine dinucleotide to sustain the tricarboxylic acid cycle and ß-oxidation. Here we examined how HDAC6 regulates TNFα production, mCI activity, mitochondrial morphology and NADH levels, and cardiac function in ischemic/reperfused diabetic hearts. METHODS: HDAC6 knockout, streptozotocin-induced type 1 diabetic, and obese type 2 diabetic db/db mice underwent myocardial ischemia/reperfusion injury in vivo or ex vivo in a Langendorff-perfused system. H9c2 cardiomyocytes with and without HDAC6 knockdown were subjected to hypoxia/reoxygenation injury in the presence of high glucose. We compared the activities of HDAC6 and mCI, TNFα and mitochondrial NADH levels, mitochondrial morphology, myocardial infarct size, and cardiac function between groups. RESULTS: Myocardial ischemia/reperfusion injury and diabetes synergistically augmented myocardial HDCA6 activity, myocardial TNFα levels, and mitochondrial fission and inhibited mCI activity. Interestingly, neutralization of TNFα with an anti-TNFα monoclonal antibody augmented myocardial mCI activity. Importantly, genetic disruption or inhibition of HDAC6 with tubastatin A decreased TNFα levels, mitochondrial fission, and myocardial mitochondrial NADH levels in ischemic/reperfused diabetic mice, concomitant with augmented mCI activity, decreased infarct size, and ameliorated cardiac dysfunction. In H9c2 cardiomyocytes cultured in high glucose, hypoxia/reoxygenation augmented HDAC6 activity and TNFα levels and decreased mCI activity. These negative effects were blocked by HDAC6 knockdown. CONCLUSIONS: Augmenting HDAC6 activity inhibits mCI activity by increasing TNFα levels in ischemic/reperfused diabetic hearts. The HDAC6 inhibitor, tubastatin A, has high therapeutic potential for acute myocardial infarction in diabetes.

Palliation of a Heterotaxy Single Ventricle Neonate with Pulmonary Atresia and Obstructed TAPVR.

Patients born with obstructed total anomalous pulmonary venous return have a high risk of morbidity and mortality in the neonatal period, which only increases when combined with single ventricle physiology and non-cardiac congenital anomalies such as heterotaxy syndrome. Despite advances in management of congenital heart disease, surgery within the first weeks of life to repair the pulmonary venous connection and establish pulmonary blood flow with a systemic-to-pulmonary shunt has historically led to disappointing outcomes. A multidisciplinary approach with pediatric interventional cardiology and cardiac surgery is required to reduce morbidity and mortality in this extremely high-risk patient population. Extending the time between birth and cardiac surgery can lessen postoperative complications and mortality risk, especially in patients with abnormal thoracoabdominal relationships. Our team was able to successfully utilize transcatheter stent placement in a vertical vein and patent ductus arteriosus to delay and stage cardiac surgeries in an infant born with obstructed total anomalous pulmonary venous return, unbalanced atrioventricular septal defect with pulmonary atresia and heterotaxy, thus reducing the morbidity and mortality associated with this diagnosis.

Demographics of Current and Aspiring Integrated Six-year Cardiothoracic Surgery Trainees.

BACKGROUND: The integrated 6-year thoracic surgery (I-6) residency model was developed in part to promote early interest in cardiothoracic surgery in diverse trainees. To determine gaps in and opportunities for recruitment of women and minority groups in the pipeline for I-6 residency, we quantified rates of progression at each training level and trends over time. METHODS: We obtained 2015 to 2019 medical student, I-6 applicant, and I-6 resident gender and race/ethnicity demographic data from the American Association of Medical Colleges and Electronic Residency Application Service public databases and Accreditation Council for Graduate Medical Education Data Resource Books. We performed χ2, Fisher exact, and Cochran-Armitage tests for trend to compare 2015 and 2019. RESULTS: Our cross-sectional analysis found increased representation of women and all non-White races/ethnicities, except Native American, at each training level from 2015 to 2019 (P < .001 for all). The greatest trends in increases were seen in the proportions of women (28% vs 22%, P = .46) and Asian/Pacific Islander (25% vs 15%, P = .08) applicants. There was also an increase in the proportions of women (28% vs 24%, P = .024) and White (61% vs 58%, P = .007) I-6 residents, with a trend for Asian/Pacific Islanders (20% vs 17%, P = .08). The proportions of Hispanic (5%) and Black/African American (2%) I-6 residents in 2019 remained low. CONCLUSIONS: I-6 residency matriculation is not representative of medical student demographics and spotlights a need to foster early interest in cardiothoracic surgery among all groups underrepresented in medicine while ensuring that we mitigate bias in residency recruitment.

Cardio-omentopexy requires a cardioprotective innate immune response to promote myocardial angiogenesis in mice.

Objective: The pedicled greater omentum, when applied onto stressed hearts using omentopexy, has been shown to be protective in humans and animals. The mechanisms underlying cardioprotection using omentopexy remain elusive. This study examined whether macrophage-mediated angiogenesis accounts for the cardioprotective effect of omentopexy in mice. Methods: C57BL/6 mice were subjected to minimally invasive transverse aortic constriction for 6 weeks and subsequent cardio-omentopexy for 8 weeks. Control mice underwent the same surgical procedures without aortic constriction or cardio-omentopexy. Results: Transverse aortic constriction led to left ventricular concentric hypertrophy, reduced mitral E/A ratio, increased cardiomyocyte size, and myocardial fibrosis in the mice that underwent sham cardio-omentopexy surgery. The negative effects of transverse aortic constriction were prevented by cardio-omentopexy. Myocardial microvessel density was elevated in the mice that underwent aortic constriction and sham cardio-omentopexy surgery, and cardio-omentopexy further enhanced angiogenesis. Nanostring gene array analysis uncovered the activation of angiogenesis gene networks by cardio-omentopexy. Flow cytometric analysis revealed that cardio-omentopexy triggered the accumulation of cardiac MHCIIloLyve1+TimD4+ (Major histocompatibility complex class IIlow lymphatic vessel endothelial hyaluronan receptor 1+ T cell immunoglobulin and mucin domain conataining 4+) resident macrophages at the omental-cardiac interface. Intriguingly, the depletion of macrophages with clodronate-liposome resulted in the failure of cardio-omentopexy to protect the heart and promote angiogenesis. Conclusions: Cardio-omentopexy protects the heart from pressure overload-elicited left ventricular hypertrophy and dysfunction by promoting myocardial angiogenesis. Cardiac MHCIIloLyve1+TimD4+ resident macrophages play a critical role in the cardioprotective effect and angiogenesis of cardio-omentopexy.

Single-Stage Surgical Management of Atrioventricular Septal Defects with Coarctation of the Aorta.

Surgical options for coarctation of aorta (CoA) with atrioventricular septal defect (AVSD) include single-stage repair vs. staged approach with neonatal CoA repair and delayed AVSD repair. The durability of left atrioventricular valve (LAVV) function after neonatal repair is questioned, and the optimal approach remains controversial. Eighteen CoA-AVSD patients who underwent single-stage repair 2005-2015 by a single surgeon were retrospectively analyzed. Fifteen patients had complete and three had partial AVSD. Birth weight was 3.19 kg (2.17-4.08). Age at surgery was 16 days (6-127). One- and ten-year survival were 80% and 69%. Freedom from reintervention was 60% and 40% at one and ten-year respectively. Reinterventions included relief of left ventricular outflow tract obstruction (LVOTO) (n = 4), repair of cleft LAVV (n = 3), and LAVV and aortic valve replacement (n = 1). Freedom from LAVV reintervention was 85.6% and 66% at 1 and 10 years respectively. There were four deaths: two post-operative and two following hospital discharge. Mortality was due to sepsis in three patients, and heart failure related to LVOTO and LAVV insufficiency in one. At 68-month (0.6-144) follow-up the majority had mild or less LAVV regurgitation, and all had normal LV dimension and systolic function. There was no recurrent arch obstruction. Single-stage surgical repair of CoA-AVSD is feasible and reasonable. Survival and freedom from reintervention in our cohort approximate those outcomes of two-stage repair with durable left AV valve function and no recurrent arch obstruction. These patients are frequently syndromic and demonstrate mortality risk from non-cardiac causes. Consideration of a single-staged approach is warranted for appropriate patients with CoA-AVSD.

Applicability and Durability of Valve-Sparing Tetralogy of Fallot Repair.

BACKGROUND: Although valve-sparing repair remains ideal for patients with tetralogy of Fallot, the durability of valve-sparing repair and which patients may have been better served with a transannular patch remain unclear. METHODS: Retrospective review was performed of tetralogy of Fallot operations at our institution from January 2008 to December 2018. Standard demographic data were collected, including echocardiographic parameters, operative details, and clinical outcomes. Statistical analysis was performed comparing the transannular patch and valve-sparing repair groups. RESULTS: Sixty-seven patients underwent tetralogy of Fallot repair with a median age of 4.5 (3.2-6.0) months and weight of 5.8 (5.2, 6.7) kg. Seventeen (25%) patients underwent transannular patch repair and 50 (75%) patients underwent valve-sparing repair. There was no difference in age or weight between patients who underwent a transannular patch repair and those who underwent a valve-sparing repair. At last follow-up (median 42 months), there was a trend of a higher peak pulmonary valve/right ventricular outflow tract gradient (P = .06) in the valve-sparing group, but no difference in the pulmonary valve annulus z-scores. Additionally, the pulmonary valve z-scores in the valve-sparing group decreased from -2.3 ± 1.0 on predischarge echocardiogram of to -1.2 ± 1.6 on last follow-up, with the peak gradient on predischarge 23 (0-37) mm Hg remaining stable on last follow-up at 18 (0-29) mm Hg. There was one reoperation: pulmonary valve replacement six years after a transannular patch. CONCLUSIONS: Obtaining a postrepair pulmonary valve z-score of -2 yields satisfactory, stable valve-sparing repair with pulmonary valve growth, acceptable gradients, minimal regurgitation, and high freedom from reintervention during follow-up.

Bioresorbable Stent to Manage Congenital Heart Defects in Children.

Intravascular stents for pediatric patients that degrade without inhibiting vessel growth remain a clinical challenge. Here, poly(L-lactide) fibers (DH-BDS) at two thicknesses, 250 µm and 300 µm, were assembled into large, pediatric-sized stents (Ø10 - Ø20 mm). Fibers were characterized mechanically and thermally, then stent mechanical properties were compared to metal controls, while mass loss and degradation kinetics modeling estimated total stent degradation time. Thicker fibers displayed lower stiffness (1969 ± 44 vs 2126 ± 37 MPa) and yield stress (117 ± 12 vs 137 ± 5 MPa) than thinner counterparts, but exhibited similar fail strength (478 ± 28 vs 476 ± 16 MPa) at higher strains (47 ± 2 vs 44 ± 2%). Stents all exhibited crystallinity between 51.3 - 54.4% and fiber glass transition temperatures of 88.6 ± 0.5 °C and 84.6 ± 0.5 °C were well above physiological ranges. Radial strength (0.31 ± 0.01 - 0.34 ± 0.02 N/mm) in thinner stents was similar to metal stents (0.24 - 0.41 N/mm) up to Ø14 mm with no foreshortening and thicker coils granted comparable radial strength (0.32 ± 0.02 - 0.34 ± 0.02 N/mm) in stents larger than Ø14 mm. Both 10 mm (1.17 ± 0.02 % and 0.86 ± 0.1 %) and 12 mm (1.1 ± 0.03% and 0.89 ± 0.1%) stents exhibited minimal weight loss over one year. Degradation kinetics models predicted full stent degradation within 2.8 - 4.5 years depending on thickness. DH-BDS exhibiting hoop strength similar to metal stents and demonstrating minimal degradation and strength loss over the first year before completely disappearing within 3 to 4.5 years show promise as a pediatric interventional alternative to current strategies.

Cardiopulmonary Bypass-Induced Inflammation and Myocardial Ischemia and Reperfusion Injury Stimulates Accumulation of Soluble MER.

OBJECTIVES: Soluble MER has emerged as a potential biomarker for delayed resolution of inflammation after myocardial injury and a therapeutic target to reduce cardiac-related morbidity and mortality in adults. The significance of soluble MER in pediatric populations, however, is unclear. We sought to investigate if soluble MER concentrations change in response to myocardial ischemia and reperfusion injury in pediatric patients. In parallel, we also sought to investigate for correlations between the change in soluble MER concentration and specific patient, bypass, and postoperative data. DESIGN: We quantified the change in plasma soluble MER concentration post- compared with precardiopulmonary bypass for each patient in a cohort of pediatric patients. Linear regression, correlation coefficients, and t tests were used to compare innate patient characteristics (i.e., sex, age, cyanotic vs acyanotic cardiac lesion), cardiac bypass data (i.e., total cardiac bypass time, total aortic cross-clamp time, perioperative steroid administration), and postcardiac bypass data (total postoperative ventilator days, total postoperative vasoactive medication days, and total postoperative ICU days) with change in soluble MER concentrations. SETTING: Whole blood samples were obtained intraoperatively at a single tertiary care children's hospital from April to October 2019. SUBJECTS: Our patient cohort included 24 pediatric patients ages ranging from birth to 19 years old with both cyanotic and acyanotic cardiac lesions. INTERVENTIONS: Retrospective analyses of pediatric blood specimens, as well as patient, bypass, and postoperative data, were performed. MEASUREMENTS AND MAIN RESULTS: We observed a statistically significant increase in soluble MER concentration post cardiac bypass in 17 of 24 patients (71%). CONCLUSIONS: Soluble MER concentrations increase with cardiopulmonary bypass-induced inflammation and myocardial ischemia and reperfusion injury in pediatric patients. The utility of soluble MER as a clinical biomarker to identify pediatric patients at risk for exacerbated postoperative outcomes after bypass-induced myocardial ischemia and reperfusion injury requires further investigation.

Bone marrow-derived AXL tyrosine kinase promotes mitogenic crosstalk and cardiac allograft vasculopathy.

Cardiac Allograft Vasculopathy (CAV) is a leading contributor to late transplant rejection. Although implicated, the mechanisms by which bone marrow-derived cells promote CAV remain unclear. Emerging evidence implicates the cell surface receptor tyrosine kinase AXL to be elevated in rejecting human allografts. AXL protein is found on multiple cell types, including bone marrow-derived myeloid cells. The causal role of AXL from this compartment and during transplant is largely unknown. This is important because AXL is a key regulator of myeloid inflammation. Utilizing experimental chimeras deficient in the bone marrow-derived Axl gene, we report that Axl antagonizes cardiac allograft survival and promotes CAV. Flow cytometric and histologic analyses of Axl-deficient transplant recipients revealed reductions in both allograft immune cell accumulation and vascular intimal thickness. Co-culture experiments designed to identify cell-intrinsic functions of Axl uncovered complementary cell-proliferative pathways by which Axl promotes CAV-associated inflammation. Specifically, Axl-deficient myeloid cells were less efficient at increasing the replication of both antigen-specific T cells and vascular smooth muscle cells (VSMCs), the latter a key hallmark of CAV. For the latter, we discovered that Axl-was required to amass the VSMC mitogen Platelet-Derived Growth Factor. Taken together, our studies reveal a new role for myeloid Axl in the progression of CAV and mitogenic crosstalk. Inhibition of AXL-protein, in combination with current standards of care, is a candidate strategy to prolong cardiac allograft survival.

Identification and analysis of circulating long non-coding RNAs with high significance in diabetic cardiomyopathy.

Diabetic cardiomyopathy (DCM) lacks diagnostic biomarkers. Circulating long non-coding RNAs (lncRNAs) can serve as valuable diagnostic biomarkers in cardiovascular disease. To seek potential lncRNAs as a diagnostic biomarker for DCM, we investigated the genome-wide expression profiling of circulating lncRNAs and mRNAs in type 2 diabetic db/db mice with and without DCM and performed bioinformatic analyses of the deregulated lncRNA-mRNA co-expression network. Db/db mice had obesity and hyperglycemia with normal cardiac function at 6 weeks of age (diabetes without DCM) but with an impaired cardiac function at 20 weeks of age (DCM) on an isolated Langendorff apparatus. Compared with the age-matched controls, 152 circulating lncRNAs, 127 mRNAs and 3355 lncRNAs, 2580 mRNAs were deregulated in db/db mice without and with DCM, respectively. The lncRNA-mRNA co-expression network analysis showed that five deregulated lncRNAs, XLOC015617, AK035192, Gm10435, TCR-α chain, and MouselincRNA0135, have the maximum connections with differentially expressed mRNAs. Bioinformatic analysis revealed that these five lncRNAs were highly associated with the development and motion of myofilaments, regulation of inflammatory and immune responses, and apoptosis. This finding was validated by the ultrastructural examination of myocardial samples from the db/db mice with DCM using electron microscopy and changes in the expression of myocardial tumor necrosis factor-α and phosphorylated p38 mitogen-activated protein kinase in db/db mice with DCM. These results indicate that XLOC015617, AK035192, Gm10435, TCR-α chain, and MouselincRNA0135 are crucial circulating lncRNAs in the pathogenesis of DCM. These five circulating lncRNAs may have high potential as a diagnostic biomarker for DCM.

Use of a Dilatable exGraft Conduit in Single-Ventricle Palliation.

Surgically paced prosthetic conduits are commonly used in the treatment of congenital heart disease. A major limitation of available prosthetic grafts is that they do not grow with the patient. We describe a human case of percutaneous balloon dilation of a surgically placed exGraft conduit (PECA Labs, Inc, Pittsburgh, PA) in a neonate with single-ventricle disease. The use of dilatable conduits could change the management of many congenital heart defects and greatly reduce both the morbidity of repeat cardiac reoperations and the deleterious effects of prolonged conduit dysfunction that accrue between surgical conduit revisions.

Pediatric Tracheal Surgery: A 25-Year Review of Slide Tracheoplasty and Tracheal Resection.

BACKGROUND: The purpose of this study was to assess the outcomes of slide tracheoplasty and tracheal resection in pediatric patients and analyze the data for predictors of outcomes. METHODS: A retrospective review of tracheal surgery from January 1, 1993 to May 1, 2018 was performed. Demographic data, operative details, perioperative data, and clinical outcomes were collected. The study investigators' management strategy has evolved over time, with less rigid bronchoscopy, more reliance on postoperative computed tomographic imaging, and the use of inhaled Ciprodex (combination of ciprofloxacin and dexamethasone) since 2007. RESULTS: The study included 41 patients, with a median age of 4.1 months and a median weight of 4.2 kg. There were 6 neonates and 24 infants. Slide tracheoplasty was performed in 27 patients (66%), and resection with end-to-end anastomosis was performed in 14 (34%). Eleven patients (27%) had a pulmonary artery sling. Simultaneous intracardiac repairs requiring cross-clamp and cardioplegia were performed in 9 patients (22%). Lung agenesis (n = 6) or severe hypoplasia (n = 2) was present in 8 patients (20%). Complications included tracheostomy in 5 patients (12%) and in-hospital death in 3 patients (7%). There were no cases of mediastinitis. Inhaled Ciprodex was used to decrease granulation tissue at suture lines. Median intubation time was 7 days, and median length of stay was 25.0 days. There was no difference in outcomes when comparing intracardiac repairs with the remaining patients, lung agenesis or hypoplasia vs the remaining cohort, or neonates vs infants. CONCLUSIONS: Slide tracheoplasty and tracheal resection are effective operative strategies for infants and children with tracheal stenosis, including patients with lung agenesis/hypoplasia. Simultaneous repair of intracardiac anomalies and pulmonary artery sling is recommended.

Use of a Modified Classic BT Shunt in a Patient With Multiple Conduit Obstructions With Positive Lupus Anticoagulant.

The use of a right ventricle-to-pulmonary artery conduit has re-emerged as a popular alternative to a systemic artery-to-pulmonary artery shunt in the Norwood procedure. Both proximal obstruction secondary to dynamic compression and distal obstruction at the anastomosis site with the pulmonary arteries are well described. In an effort to prevent complications, a technique where in the conduit is placed through the entire full thickness, or dunked, through the RV free wall has been described. We report a case of a patient with HLHS and positive lupus anticoagulant who developed recurrent conduit obstructions. The "Sano" was abandoned in favor of an autologous source of pulmonary blood flow-the modified Blalock-Taussig shunt using the "turn down" of the carotid artery.

Normalization of hemodynamics is delayed in patients with a single ventricle after pediatric heart transplantation.

OBJECTIVES: The time course for hemodynamic normalization after pediatric heart transplantation has not been well characterized. We hypothesized that patients with a single ventricle would normalize later than those with dilated cardiomyopathy. Establishing the expected course based on the underlying pathophysiology will allow identification of patients who are outliers, requiring further investigation. METHODS: We performed a retrospective review of patients with dilated cardiomyopathy, Glenn, and Fontan who underwent heart transplantation from January 2007 to December 31, 2017, and had 6-month and 1-year catheterization data. Hemodynamic data were examined for sustained normalization of pressures. Myocardial biopsies were reviewed for clinically significant rejection within the first year. RESULTS: Ninety-four patients comprised the cohort (47 dilated cardiomyopathy, 18 Glenn, 29 Fontan) with a median age of 6.8 (12) years. Patients with dilated cardiomyopathy were more likely to normalize hemodynamics by 6 months (85% vs 28% Fontan, 44% Glenn, P < .05), and 96% of patients with dilated cardiomyopathy had normalized hemodynamics by 1 year (vs 62% Fontan, 78% Glenn, P < .001). The pulmonary capillary wedge pressure at 6 months was higher in patients who underwent the Fontan and Glenn (median 12.8 [8.8] mm Hg and 11.2 [5.9] mm Hg, respectively) compared with patients with dilated cardiomyopathy (7.0 [3.3] mm Hg, P < .001). Patients with dilated cardiomyopathy demonstrated normalized hemodynamics earlier (121 ± 72 days) than patients who underwent the Fontan (329 ± 62 days) and Glenn (233 ± 11 days, P < .001). Eighteen patients (19%) experienced significant rejection, which was not increased in patients with delayed hemodynamic normalization. The 6-month pulmonary capillary wedge pressure was associated with delayed normalization (hazard ratio, 1.36; 95% confidence interval, 1.16-1.60; P < .001). CONCLUSIONS: Patients with a single ventricle demonstrated delayed hemodynamic normalization compared with dilated cardiomyopathy heart transplant recipients, without affecting survival or need for retransplantation.

Mitral Valve Surgery in the First Year of Life.

Data are limited on outcomes associated with mitral valve surgery in infants. Prior studies report high mortality and increased risk for late cardiac failure particularly for those with mitral stenosis. We sought to evaluate outcomes in patients with mitral stenosis (MS) or regurgitation (MR) who had mitral valvuloplasty or replacement in the first year of life. A retrospective analysis of all patients in a single institution who underwent mitral valvuloplasty or replacement in their first year of life from 2004 to 2016 (n = 25), excluding patients with single ventricle pathology or those undergoing surgery for atrioventricular canal defect, was carried out. Median age and weight at surgery were 76.5 days (range 2-329) and 4.5 kg (range 3.0-10.1), respectively. The primary mitral pathology was MR in 16 and MS in 9 patients. Median follow-up among living patients was 4 years (range 106 days-12.3 years). Overall survival was 96% at 30 days and 87.8% at 1, 5, and 10 years. There were three early deaths (12%), all within 6 weeks of surgery. There were no late deaths. Three patients required valve replacement, 1 of which had a primary mitral valve replacement and died within 30 days of surgery. Re-intervention-free survival (surgical and catheter based) was 83.8%, 73.3%, and 48.9% at 1, 5, and 10 years per Kaplan-Meier estimates. There was no difference in re-intervention-free survival between patients with MR versus MS. No risk factors for death or re-intervention were identified. Mitral valvuloplasty and replacement can be performed in infants under 1 year of age with acceptable survival and need for re-intervention.

Genome-wide differential expression profiling of lncRNAs and mRNAs associated with early diabetic cardiomyopathy.

Diabetic cardiomyopathy is one of the main causes of heart failure and death in patients with diabetes. There are no effective approaches to preventing its development in the clinic. Long noncoding RNAs (lncRNA) are increasingly recognized as important molecular players in cardiovascular disease. Herein we investigated the profiling of cardiac lncRNA and mRNA expression in type 2 diabetic db/db mice with and without early diabetic cardiomyopathy. We found that db/db mice developed cardiac hypertrophy with normal cardiac function at 6 weeks of age but with a decreased diastolic function at 20 weeks of age. LncRNA and mRNA transcripts were remarkably different in 20-week-old db/db mouse hearts compared with both nondiabetic and diabetic controls. Overall 1479 lncRNA transcripts and 1109 mRNA transcripts were aberrantly expressed in 6- and 20-week-old db/db hearts compared with nondiabetic controls. The lncRNA-mRNA co-expression network analysis revealed that 5 deregulated lncRNAs having maximum connections with differentially expressed mRNAs were BC038927, G730013B05Rik, 2700054A10Rik, AK089884, and Daw1. Bioinformatics analysis revealed that these 5 lncRNAs are closely associated with membrane depolarization, action potential conduction, contraction of cardiac myocytes, and actin filament-based movement of cardiac cells. This study profiles differently expressed lncRNAs in type 2 mice with and without early diabetic cardiomyopathy and identifies BC038927, G730013B05Rik, 2700054A10Rik, AK089884, and Daw1 as the core lncRNA with high significance in diabetic cardiomyopathy.

Mitral Valve Replacement in Infants Using a 15-mm Mechanical Valve.

BACKGROUND: The 15-mm mechanical valve was approved by the US Food and Drug Administration in March 2018. We review our experience in infants with this valve in the mitral position (MV), focusing on outcomes and timing to repeat MV replacement (MVR). METHODS: Between 2006 and 2017 7 patients underwent eight MVRs (one repeat) with a 15-mm mechanical valve. Retrospective chart review was performed to examine short- and long-term outcomes. RESULTS: There were no operative deaths. Mean follow-up was 5.8 ± 4.8 years (range, 0.72 to 11.1). Six patients underwent an MV operation 53 ± 39 days (range, 9 to 118) before MVR with the 15-mm valve. All patients were on mechanical ventilatory support at the time of operation. Mean age, body weight, and body surface area at time of 15-mm MVR were 0.5 ± 0.3 years (range, 0.2 to 0.9), 5.6 ± 0.8 kg (range, 4.8 to 6.6), and 0.29 ± 0.03 m2 (range, 0.27 to 0.32), respectively. Two patients required pacemaker implantation for atrioventricular block, both after their second MVR. Two patients are well at 16 and 24 months. Four patients underwent repeat MVR because of somatic growth and patient-prosthesis mismatch. Mean time to repeat MVR was 23 months (range, 6 to 40). There were two late deaths, one at 10 months unrelated to the valve in a child with a chromosomal abnormality. The other child had a congenital diaphragmatic hernia, early valve thrombosis, and died of multiple complications after a fourth MVR. CONCLUSIONS: The 15-mm mechanical valve was useful in treating MV disease in infants 2 to 12 months of age. This newly approved smallest available mechanical valve has a predicted mean time to replacement of 23 months in the mitral position.