Regionalization or Access to Care? A Joint Pediatric Heart Care Program That Achieves Both: One Program-Two Sites.

Background: Regionalization of care for children with congenital heart disease has been proposed as a method to improve outcomes. This has raised concerns about limiting access to care. We present the details of a joint pediatric heart care program (JPHCP) which utilized regionalization and actually improved access to care. Methods: In 2017, Kentucky Children's Hospital (KCH) launched the JPHCP with Cincinnati Children's Hospital Medical Center (CCHMC). This unique satellite model was the product of several years of planning, leading to a comprehensive strategy with shared personnel, conferences, and a robust transfer system; "one program-two sites." Results: Between March 2017 and the end of June 2022, 355 operations were performed at KCH under the auspices of the JPHCP. As of the most recent published Society of Thoracic Surgeons (STS) outcome report (through the end of June 2021), for all STAT categories, the JPHCP at KCH outperformed the STS overall in postoperative length of stay, and the mortality rate was lower than expected for the case mix. Of the 355 operations, there were 131 STAT 1, 148 STAT 2, 40 STAT 3, and 36 STAT 4 operations, with two operative mortalities: an adult undergoing surgery for Ebstein anomaly, and a premature infant who died from severe lung disease many months after aortopexy. Conclusions: With a select case mix, and by affiliating with a large volume congenital heart center, the creation of the JPHCP at KCH was able to achieve excellent congenital heart surgery results. Importantly, access to care was improved for those children at the more remote location utilizing this one program-two sites model.

Prevalence of ICU Delirium in Postoperative Pediatric Cardiac Surgery Patients.

OBJECTIVES: The objective of this study was to determine the prevalence of ICU delirium in children less than 18 years old that underwent cardiac surgery within the last 30 days. The secondary aim of the study was to identify risk factors associated with ICU delirium in postoperative pediatric cardiac surgical patients. DESIGN: A 1-day, multicenter point-prevalence study of delirium in pediatric postoperative cardiac surgery patients. SETTING: Twenty-seven pediatric cardiac and general critical care units caring for postoperative pediatric cardiac surgery patients in North America. PATIENTS: All children less than 18 years old hospitalized in the cardiac critical care units at 06:00 on a randomly selected, study day. INTERVENTIONS: Eligible children were screened for delirium using the Cornell Assessment of Pediatric Delirium by the study team in collaboration with the bedside nurse. MEASUREMENT AND MAIN RESULTS: Overall, 181 patients were enrolled and 40% (n = 73) screened positive for delirium. There were no statistically significant differences in patient demographic information, severity of defect or surgical procedure, past medical history, or postoperative day between patients screening positive or negative for delirium. Our bivariate analysis found those patients screening positive had a longer duration of mechanical ventilation (12.8 vs 5.1 d; p = 0.02); required more vasoactive support (55% vs 26%; p = 0.0009); and had a higher number of invasive catheters (4 vs 3 catheters; p = 0.001). Delirium-positive patients received more total opioid exposure (1.80 vs 0.36 mg/kg/d of morphine equivalents; p < 0.001), did not have an ambulation or physical therapy schedule (p = 0.02), had not been out of bed in the previous 24 hours (p < 0.0002), and parents were not at the bedside at time of data collection (p = 0.008). In the mixed-effects logistic regression analysis of modifiable risk factors, the following variables were associated with a positive delirium screen: 1) pain score, per point increase (odds ratio, 1.3; 1.06-1.60); 2) total opioid exposure, per mg/kg/d increase (odds ratio, 1.35; 1.06-1.73); 3) SBS less than 0 (odds ratio, 4.01; 1.21-13.27); 4) pain medication or sedative administered in the previous 4 hours (odds ratio, 3.49; 1.32-9.28); 5) no progressive physical therapy or ambulation schedule in their medical record (odds ratio, 4.40; 1.41-13.68); and 6) parents not at bedside at time of data collection (odds ratio, 2.31; 1.01-5.31). CONCLUSIONS: We found delirium to be a common problem after cardiac surgery with several important modifiable risk factors.

Myocardial fibrosis, diastolic dysfunction and elevated liver stiffness in the Fontan circulation.

INTRODUCTION: Single ventricle diastolic dysfunction and hepatic fibrosis are frequently observed in patients with a Fontan circulation. The relationship between adverse haemodynamics and end-organ fibrosis has not been investigated in adolescents and young adults with Fontan circulation. METHODS: Prospective observational study of Fontan patients who had a cardiac catheterisation. Cardiac MRI with T1 mapping was obtained to measure extracellular volume (ECV), a marker of myocardial fibrosis. Hepatic magnetic resonance elastography was performed to assess liver shear stiffness. Serum biomarkers of fibrosis including matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) were measured. Very high ECV was defined as >30% and elevated serum biomarkers as >75th percentile for each biomarker. RESULTS: 25 Fontan patients (52% female) with mean age of 16.3±6.8 years were included. Mean ECV was 28%±5%. There was a significant correlation between ECV and systemic ventricular end-diastolic pressure (r=0.42, p=0.03) and between ECV and liver stiffness (r=0.45, p=0.05). Patients with elevated ECV demonstrated elevations in MMPs and TIMPs. Similarly, patients with elevated MMPs and TIMPs had greater liver stiffness compared with patients with normal levels of these biomarkers. CONCLUSIONS: In Fontan patients, cardiac magnetic resonance evidence of myocardial fibrosis is associated with diastolic dysfunction, increased liver stiffness and elevated circulating biomarkers of fibrosis. These findings suggest the presence of a profibrotic milieu, with end-organ implications, in some patients with Fontan circulation.

Repeated Remote Ischemic Conditioning Reduces Doxorubicin-Induced Cardiotoxicity.

OBJECTIVES: This study investigated the cardioprotective effect of repeated remote ischemic preconditioning (rRIC) on doxorubicin-induced cardiotoxicity in mice. BACKGROUND: Doxorubicin is an effective chemotherapeutic agent for a wide range of tumor types but its use and dosing are limited by acute and chronic cardiotoxicity. Remote ischemic conditioning (RIC) is cardioprotective in multiple cardiovascular injury models, but the effectiveness of rRIC in doxorubicin-induced cardiotoxicity has not been fully elucidated. METHODS: rRIC was performed on mice before and after doxorubicin administration. Cardiac function was assessed by echocardiography and myocardial biology was tested by molecular approaches. RESULTS: Doxorubicin administration induced acute cardiotoxicity, as indicated by reduced cardiac function, reduced myocyte cross-section area and increased extracellular collagen deposition, increased circulating cardiac muscle damage markers, and decreased heart weight. Doxorubicin also adversely affected other organs, including the kidney, liver, and spleen, as evaluated by circulating markers or organ weight loss. rRIC not only abrogated doxorubicin-induced cardiotoxicity (left ventricular ejection fraction, doxorubicin 47.5 ± 1.1%, doxorubicin + rRIC 51.6 ± 0.7%, p = 0.017), but also was associated with multiorgan protection. Within the myocardium, rRIC attenuated doxorubicin-induced cardiomyocyte apoptosis, reduced inflammation, and increased autophagy signaling. CONCLUSIONS: rRIC may be a promising approach to reduce doxorubicin-induced cardiotoxicity.

Reduced biventricular contractility during exercise in adults with small, unrepaired ventricular septal defects: an echocardiographic study.

OBJECTIVES: Small ventricular septal defects are often considered to be without long-term haemodynamic consequences and so the majority remains unrepaired. However, we recently showed reduced functional capacity and altered right ventricular morphology in adults with small, unrepaired ventricular septal defects. The underlying mechanisms behind these findings remain unclear, and so, biventricular contractility during exercise was evaluated. METHODS: Adults with small, unrepaired ventricular septal defects and healthy controls were examined with echocardiography during supine bicycle exercise with increasing workload. Tissue velocity Doppler was used for evaluating isovolumetric acceleration and systolic velocities during exercise. RESULTS: In total, 34 patients with ventricular septal defects, a median shunt- ratio of 1.2 (26 ± 6 years), and 28 healthy peers (27 ± 5 years) were included. Right ventricular isovolumetric acceleration was lower in patients as compared with controls at rest (97 ± 40 vs 158 ± 43 cm/s2, P = 0.01) and at peak heart rate (222 ± 115 vs 410 ± 120 cm/s2, P < 0.01). Peak systolic velocities were similar at rest, but differed with exercise (13 ± 3 vs 16 ± 3 cm/s, P = 0.02). Left ventricular isovolumetric acceleration was lower in patients as compared with controls throughout the test (P < 0.01). Septal isovolumetric acceleration was similar at rest, but reduced during increasing exercise as compared with controls (220 ± 108 vs 303 ± 119 cm/s2, P = 0.03). Left ventricular isovolumetric acceleration was negatively correlated with the shunt- ratio, and right ventricular and septal peak systolic velocities were positively correlated with lower functional capacity. CONCLUSIONS: Altered biventricular contractility is present during exercise in adults with small, unrepaired ventricular septal defects. These results add to the growing number of studies showing that long-term outcome in unrepaired ventricular septal defects may not be benign.

Dynamic Myocardial Response to Exercise in Childhood Cancer Survivors Treated with Anthracyclines.

BACKGROUND: Anthracycline cardiotoxicity can cause significant long-term morbidity in childhood cancer survivors (CCS), but many CCS do not manifest clinical symptoms until adulthood. The aims of this study were to characterize the dynamic myocardial response to exercise of CCS at long-term follow-up by combining semisupine bicycle exercise stress echocardiography with myocardial imaging techniques and to establish whether semisupine bicycle exercise stress echocardiography could identify CCS with abnormal exercise response. METHODS: This was a single-center prospective cross-sectional study. One hundred CCS and 51 control subjects underwent semisupine bicycle exercise stress echocardiography. Color Doppler tissue imaging peak systolic (s') and diastolic (e') velocities, myocardial acceleration during isovolumic contraction, and longitudinal strain were measured at rest and at incremental heart rates in the left ventricular (LV) lateral wall, basal septum, and right ventricle. The relationship with increasing heart rate was evaluated for each parameter by plotting the values against heart rate at each stage of exercise. Kernel density estimate was used to establish the normality of the individual CCS exercise responses. RESULTS: At rest, no significant differences were found for LV lateral wall, right ventricular (RV), and basal septal systolic and diastolic velocities between CCS and control subjects. Only septal e' was lower in CCS. LV longitudinal strain was similar between groups, while RV longitudinal strain was lower in CCS. At peak exercise, LV lateral wall, RV, and septal s' were not different between groups, while e' were significantly lower in CCS. LV lateral wall and septal isovolumic acceleration were also reduced in CCS. LV longitudinal strain was different between groups, while RV longitudinal strain was similar. The dynamic response of Doppler tissue imaging velocities, isovolumic acceleration, and strain was similar between CCS and control subjects. Kernel density estimate analysis confirmed that most CCS responses were within the normal range. CONCLUSIONS: At 10-year follow-up, anthracycline-treated CCS with normal baseline ejection fractions have LV and RV systolic and diastolic myocardial exercise response comparable with that of control subjects. Minor differences were observed between CCS and control subjects at rest and at peak exercise, but the dynamic response is within the normal range.

Fontan Failure and Death in Contemporary Fontan Circulation: Analysis From the Last Two Decades.

BACKGROUND: We sought to evaluate the incidence of Fontan failure or complication and its relation to death in patients having contemporary Fontan strategies over 2 decades. METHODS: Five hundred patients who underwent Fontan completion (extracardiac, n = 326; lateral tunnel, n = 174) from 1985 to 2012 were reviewed. Patient characteristics, modes of Fontan failure/complication and death, and predictors for Fontan failure/complication and death were analyzed. RESULTS: There were 23 early deaths (4.6%) and 17 late deaths (3.4%), with no early death since 2000. Survival has improved over time (p < 0.001). Twenty-three of 40 patients who died were identified as Fontan failure before death, including ventricular dysfunction (n = 14), pulmonary vascular dysfunction (n = 4), thromboembolism (n = 2), and arrhythmia (n = 4). Mode of death was circulatory failure (n = 18), multiorgan failure (n = 6), pulmonary failure (n = 3), cerebral/renal (n = 5), and sudden death (n = 4). Modes of failure/complication were directly (65%) or conceivably (10%) related to death in 30 of 40 patients (75%). Forty-eight percent of survivors had late Fontan complication(s). Five-year freedom from late Fontan complication was lower among patients who died compared with patients who survived (29.4% versus 53.3%, p < 0.001). Ventricular dysfunction (p = 0.001) and higher pulmonary artery pressures (p < 0.001) after Fontan were predictors for death. Longer cardiopulmonary bypass time (p = 0.032) and reinterventions (p < 0.001) were predictors for late Fontan complication. CONCLUSIONS: Early death in the early era has been overcome. Yet the incidence and causes of late death remain unchanged. There was a strong causative relationship between the mode of Fontan failure/complication and death, indicating the importance of early recognition and treatment of Fontan failure/complication.

Effect of remote ischemic conditioning on myocardial perfusion in patients with suspected ischemic coronary artery disease.

BACKGROUND: Remote ischemic conditioning (RIC) confers protection against myocardial ischemia-reperfusion injury and may modulate coronary blood flow. We investigated whether RIC affects resting myocardial perfusion (MP) in patients with suspected ischemic coronary artery disease by quantitative MP imaging. METHODS AND RESULTS: We included 49 patients with suspected ischemic coronary artery disease. Resting MP was quantified by 82Rubidium positron emission tomography/computed tomography (82Rb-PET/CT) imaging before and after RIC, performed as four cycles of 5 minutes upper arm ischemia and reperfusion. Subsequent adenosine 82Rb-PET/CT stress-imaging identified non-ischemic and reversibly ischemic myocardial segments. MicroRNA-144 plasma levels were measured before and after RIC. Normalized for rate pressure product, RIC did not affect MP globally (P = .64) or in non-ischemic myocardial segments (P = .58) but decreased MP in reversibly ischemic myocardial segments (-0.11 mL/min/g decrease in MP following RIC; 95% CI -0.17 to -0.06, P < .001). However, we found no effect of RIC when MP was normalized for cardiac work. MicroRNA-144 plasma levels increased following RIC (P = .006) but did not correlate with a change in global MP in response to RIC (P = .40). CONCLUSIONS: RIC did not substantially affect resting MP globally or in non-ischemic and reversibly ischemic myocardial territories in patients with suspected ischemic coronary artery disease.

A rabbit model of progressive chronic right ventricular pressure overload.

OBJECTIVES: Right ventricular (RV) failure from increased pressure loading is a frequent consequence of acquired and congenital heart diseases. However, the mechanisms involved in their pathophysiology are still unclear, and few data exist on RV pressure-loading models and early versus late effects on RV and left ventricular responses. We characterized a rabbit model of chronic RV pressure overload and early-late effects on biventricular function. METHODS: Twenty-one New Zealand white rabbits were randomized into 3 groups: (i) sham, (ii) pulmonary artery (PA) banding (PAB) for 3 weeks (PAB3W) and (iii) PAB for 6 weeks (PAB6W). Progressive RV pressure overload was created by serial band inflation using an adjustable device. Molecular, echocardiographic and haemodynamic studies were performed. RESULTS: RV pressure overload was achieved with clinical manifestations of RV failure. Heart and liver weights were significantly higher after PAB. PAB-induced echocardiographic ventricular remodelling increased wall thickness and stress and ventricular dilation. Cardiac output (ml/min) (sham 172.4 ± 42.86 vs PAB3W 103.1 ± 23.14 vs PAB6W 144 ± 60.9, P = 0.0027) and systolic and diastolic functions decreased; with increased RV end-systolic and end-diastolic pressures (mmHg) (sham 1.6 ± 0.66 vs PAB3W 3.9 ± 1.8 vs PAB6W 5.2 ± 2.2, P = 0.0103), despite increased contractility [end-systolic pressure-volume relationship (mmHg/ml), sham 3.76 ± 1.76 vs PAB3W 12.21 ± 3.44 vs PAB6W 19.4 ± 6.88, P < 0.0001]. Functional parameters further worsened after PAB6W versus PAB3W. LV contractility increased in both the PAB groups, despite worsening of other invasive measures of systolic and diastolic functions. CONCLUSIONS: We describe a novel, unique model of chronic RV pressure overload leading to early biventricular dysfunction and fibrosis with further progression at 6 weeks. These findings can aid in guiding management.

Prevention of contrast-induced nephropathy by limb ischemic preconditioning: underlying mechanisms and clinical effects.

Contrast-induced nephropathy (CIN) is an important complication following diagnostic radiographic imaging and interventional therapy. It results from administration of intravascular iodinated contrast media (CM) and is currently the third most common cause of hospital-acquired acute kidney injury. CIN is associated with increased morbidity, prolonged hospitalization, and higher mortality. Although the importance of CIN is widely appreciated, and its occurrence can be mitigated by the use of pre- and posthydration protocols and low osmolar instead of high osmolar iodine-containing CM, specific prophylactic therapy is lacking. Remote ischemic preconditioning (RIPC), induced through short cycles of ischemia-reperfusion applied to the limb, is an intriguing new strategy that has been shown to reduce myocardial infarction size in patients undergoing emergency percutaneous coronary intervention. Furthermore, multiple proof-of-principle clinical studies have suggested benefit in several other ischemia-reperfusion syndromes, including stroke. Perhaps somewhat surprisingly, RIPC also is emerging as a promising strategy for CIN prevention. In this review, we discuss current clinical and experimental developments regarding the biology of CIN, concentrating on the pathophysiology of CIN, and cellular and molecular mechanisms by which limb ischemic preconditioning may confer renal protection in clinical and experimental models of CIN.

Intravenous miR-144 inhibits tumor growth in diethylnitrosamine-induced hepatocellular carcinoma in mice.

Previous in vitro studies have demonstrated that miR-144 inhibits hepatocellular carcinoma cell proliferation, invasion, and migration. We have shown that miR-144, injected intravenously, is taken up by the liver and induces endogenous hepatic synthesis of miR-144. We hypothesized that administered miR-144 has tumor-suppressive effects on liver tumor development in vivo. The effects of miR-144 on tumorigenesis and tumor growth were tested in a diethylnitrosamine-induced hepatocellular carcinoma mouse model. MiR-144 injection had no effect on body weight but significantly reduced diethylnitrosamine-induced liver enlargement compared with scrambled microRNA. MiR-144 had no effect on diethylnitrosamine-induced liver tumor number but reduced the tumor size above 50%, as evaluated by magnetic resonance imaging (scrambled microRNA 23.07 ± 5.67 vs miR-144 10.38 ± 2.62, p < 0.05) and histological analysis (scrambled microRNA 30.75 ± 5.41 vs miR-144 15.20 ± 3.41, p < 0.05). The levels of miR-144 was suppressed in tumor tissue compared with non-tumor tissue in all treatment groups (diethylnitrosamine-phosphate-buffered saline non-tumor 1.05 ± 0.09 vs tumor 0.54 ± 0.08, p < 0.01; diethylnitrosamine-scrambled microRNA non-tumor 1.23 ± 0.33 vs tumor 0.44 ± 0.10, p < 0.05; diethylnitrosamine-miR-144 non-tumor 54.72 ± 11.80 vs tumor 11.66 ± 2.75, p < 0.01), but injection of miR-144 greatly increased miR-144 levels both in tumor and non-tumor tissues. Mechanistic studies showed that miR-144 targets epidermal growth factor receptor and inhibits the downstream Src/AKT signaling pathway which has previously been implicated in hepatocellular carcinoma tumorigenesis. Exogenously delivered miR-144 may be a therapeutic strategy to suppress tumor growth in hepatocellular carcinoma.

Endothelial Function and Arterial Stiffness Relate to Functional Outcomes in Adolescent and Young Adult Fontan Survivors.

BACKGROUND: Fontan survivors demonstrate diminished vascular function and functional outcomes, but the relationships between these measures have not been established. METHODS AND RESULTS: We performed a cross-sectional study of 60 Fontan survivors (52% male) with a mean age of 13.9±4.1 years and mean Fontan duration of 9.9±4.2 years. Multimodality assessment of endothelial function (reactive hyperemia index and flow-mediated dilation) and arterial stiffness (augmentation index and baseline pulse amplitude) was performed with peripheral arterial tonometry and brachial flow-mediated dilation. Aerobic capacity was determined using cardiopulmonary exercise testing; mean peak and percentage of predicted oxygen consumption (VO2) were 27.8±7.6 mL/kg per minute and 71.0±21.2%, respectively. Quality of life and physical activity were assessed using the Pediatric Quality of Life Inventory (PedsQL) and the Physical Activity Questionnaire. Vascular measures served as predictor variables, whereas functional measures served as outcome variables. In all cases, worse vascular measures were associated with worse functional measures. Flow-mediated dilation-derived reactive hyperemia index (P<0.05) was positively associated with VO2 at anaerobic threshold. Peripheral arterial tonometry-derived baseline pulse amplitude (P<0.05) was negatively associated with the ratio of minute ventilation to carbon dioxide at anaerobic threshold. Flow-mediated dilation-derived reactive hyperemia index and peripheral arterial tonometry-derived augmentation index (P<0.05) were positively and negatively associated, respectively, with peak VO2. Maximum flow-mediated dilation (P<0.05) was positively associated with Physical Activity Questionnaire score. Peripheral arterial tonometry-derived augmentation index and baseline pulse amplitude (P<0.05) were negatively associated with parent-reported PedsQL total and physical heath summary scores. CONCLUSIONS: Increased arterial stiffness and decreased endothelial function are associated with lower aerobic capacity, physical activity, and quality of life in adolescent and young adult Fontan survivors. Understanding the cause-effect relationship between vascular function and functional outcomes is an important next step.

Short-term remote ischemic preconditioning is not associated with improved blood pressure and exercise capacity in young adults.

We sought to determine whether a 9-day remote ischemic preconditioning (IPC) causes improvements in exercise performance, energetics, and blood pressure. Ten participants (mean age 24 ± 4 years) had no changes in aerobic capacity (preintervention: 38 ± 10 mL/(kg·min)(-1) vs. postintervention: 38 ± 10 mL/(kg·min)(-1)), blood pressure (preintervention: 112 ± 7/66 ± 6 mm Hg vs. postintervention: 112 ± 10/62 ± 5 mm Hg), cardiac phosphocreatinine-to-adenosine-triphosphate ratio (preintervention: 2.1 ± 0.5 vs. postintervention: 2.3 ± 0.4), and postexercise skeletal muscle phosphocreatine recovery (preintervention: 34 ± 11 s vs. postintervention: 31 ± 11 s). Short-term remote IPC may be ineffective in improving these outcomes.

Vicious circle between progressive right ventricular dilatation and pulmonary regurgitation in patients after tetralogy of Fallot repair? Right heart enlargement promotes flow reversal in the left pulmonary artery.

BACKGROUND: The left pulmonary artery (LPA) contributes more than the right (RPA) to total pulmonary regurgitation (PR) in patients after tetralogy of Fallot (TOF) repair, but the mechanism of this difference is not well understood. This study aimed to analyze the interplay between heart and lung size, mediastinal geometry, and differential PR. METHODS: Forty-eight Cardiovascular Magnetic Resonance (CMR) studies in patients after TOF repair were analyzed. In addition to the routine blood flow and ventricular volume quantification cardiac angle between the thoracic anterior-posterior line and the interventricular septum, right and left lung areas as well as right and left hemithorax areas were measured on an axial image. Statistical analysis was performed to compare flow parameters between RPA and LPA and to assess correlation among right ventricular volume, pulmonary blood flow parameters and lung area. RESULTS: There was no difference between LPA and RPA diameters. The LPA showed significantly less total forward flow (2.49 ± 0.87 L/min/m(2) vs 2.86 ± 0.89 L/min/m(2); p = 0.02), smaller net forward flow (1.40 ± 0.51 vs 1.89 ± 0.60 mL/min/m(2); p = <0.001), and greater regurgitant fraction (RF) (34 ± 10 % vs 43 ± 12 %; p = 0.001) than the RPA. There was no difference in regurgitant flow volume between RPA and LPA (p = 0.29). Indexed right ventricular end-diastolic volume (RVEDVi) correlated with LPA RF (R = 0.48, p < 0.001), but not with RPA RF (p = 0.09). Larger RVEDVi correlated with a more leftward cardiac axis (R = 0.46, p < 0.001) and with smaller left lung area (R = -0.58, p < 0.001). LPA RF, but not RPA RF, correlated inversely with left lung area (R = -0.34, p = 0.02). The follow-up CMRs in 20 patients showed a correlation of the rate of RV enlargement with the rates of LPA RF worsening (R = 0.50, p = 0.03), and of increasing left lung compression (R = -0.55, p = 0.012). CONCLUSION: An enlarged and levorotated heart is associated with left lung compression and impaired flow into the left lung.

Time Dependent Distribution of MicroRNA 144 after Intravenous Delivery.

BACKGROUND: miR-144 has potential benefits in protecting against myocardial ischemia and suppression of tumor growth. We have previously shown that a single intravenous injection of miR-144 provides potent cardioprotection, but its kinetics and distribution are not known. METHODS: Single stranded mature miR-144 or Cy3-labelled-miR-144 was delivered into C57/B6 mice by tail vein injection. RESULTS: After intravenous injection, the signal of Cy3-labelled-miR-144 in the kidney, brain, heart and liver peaks at 60 minutes, and is predominantly localised to the endothelium at that stage. In the kidney and heart, Cy3-labelled-miR-144 signal is detectable within the parenchymal tissues for at least 3 days, after which it starts to decrease, but brain Cy3-miR-144 signal rapidly decreases after 1 hour, and is lost at day 1, with no parenchymal uptake detected. Cy3-miR-144 signal can be detected until day 28 in the liver. Stem loop RTPCR confirmed the temporal pattern shown by miR-144 in kidney, brain and heart, but in liver there was a continuous rise following the initial injection until day 28 with no signs of decrease, suggesting de-novo synthesis. CONCLUSION: There is early endothelial uptake of injected miR-144 followed by organ-specific distribution and kinetics. In the liver, there appears to be a positive feedback process that leads to continued accumulation of miR-144 that persists for at least 28 days. These observations should be taken into account when designing experiments utilizing parenteral miR-144 and assessing the biology of its actions.

Insulin resistance and inflammation are a cause of hyperglycemia after pediatric cardiopulmonary bypass surgery.

OBJECTIVES: Hyperglycemia is common after pediatric cardiopulmonary bypass (CPB) surgery and is attributed to a state of insulin resistance. We examined the role of CPB-induced inflammation on postoperative plasma glucose, insulin, and the glucose-to-insulin ratio, which was used as a marker of insulin resistance; a decrease in the ratio reflects increased resistance. METHODS: We conducted an ancillary study on a previously published randomized trial of children undergoing CPB surgery. Serial blood glucose, insulin, and cytokines were drawn after CPB and at selected intervals for up to 48 hours after surgery. The primary outcome was plasma insulin levels and glucose-to-insulin ratio. Glucose delivery and feeding status were monitored for potential modifying effects. RESULTS: The 299 children studied were predominantly male (55%) with a median age of 2.7 (interquartile range [IQR]: 0.5-6.5) years, and weight of 12.6 (IQR: 6.4-10.8) kg. Operations had a median Society of Thoracic Surgery-European Association for Cardio-Thoracic Surgery complexity score of 1 (IQR: 1-2) and CPB time of 82 (IQR: 58-122) minutes. Hyperglycemia occurred in 85% of subjects; odds of hyperglycemia peaked at 6 hours after CPB. Plasma glucose was associated with increased insulin and a lower glucose-to-insulin ratio. Increased interleukin (IL)-6 concentrations were associated with increased glucose (estimate [EST]: 0.55 (±0.13) mmol/L; P < .001) and insulin (EST: 1.14 (±0.12) µmol/L; P < .001) in linear regression adjusted for repeated measures. Paradoxically, increased cytokines were associated with an increased glucose-to-insulin ratio (EST: 0.21 (±0.03) mmol/µmol; P < .001). CONCLUSIONS: Hyperglycemia after pediatric CPB surgery is associated with hyperinsulinemia, which may reflect insulin resistance in some patients. Inflammation induced by CPB may play a causative role in insulin resistance.