Simvastatin restores pulmonary endothelial function in the setting of pulmonary over-circulation.

Statin therapy is a cornerstone in the treatment of systemic vascular diseases. However, statins have failed to translate as therapeutics for pulmonary vascular disease. Early pulmonary vascular disease in the setting of congenital heart disease (CHD) is characterized by endothelial dysfunction, which precedes the more advanced stages of vascular remodeling. These features make CHD an ideal cohort in which to re-evaluate the potential pulmonary vascular benefits of statins, with a focus on endothelial biology. However, it is critical that the full gamut of the pleiotropic effects of statins in the endothelium are uncovered. The purpose of this investigation was to evaluate the therapeutic potential of simvastatin for children with CHD and pulmonary over-circulation, and examine mechanisms of simvastatin action on the endothelium. Our data demonstrate that daily simvastatin treatment preserves endothelial function in our shunt lamb model of pulmonary over-circulation. Further, using pulmonary arterial endothelial cells (PAECs) isolated from Shunt and control lambs, we identified a new mechanism of statin action mediated by increased expression of the endogenous Akt1 inhibitor, C-terminal modifying protein (CTMP). Increases in CTMP were able to decrease the Akt1-mediated mitochondrial redistribution of endothelial nitric oxide synthase (eNOS) which correlated with increased enzymatic coupling, identified by increases in NO generation and decreases in NOS-derived superoxide. Together our data identify a new mechanism by which simvastatin enhances NO signaling in the pulmonary endothelium and identify CTMP as a potential therapeutic target to prevent the endothelial dysfunction that occurs in children born with CHD resulting in pulmonary over-circulation.

Respiratory mechanics and gas exchange in an ovine model of congenital heart disease with increased pulmonary blood flow and pressure.

In a model of congenital heart disease (CHD), we evaluated if chronically increased pulmonary blood flow and pressure were associated with altered respiratory mechanics and gas exchange. Respiratory mechanics and gas exchange were evaluated in 6 shunt, 7 SHAM, and 7 control age-matched lambs. Lambs were anesthetized and mechanically ventilated for 15 min with tidal volume of 10 mL/kg, positive end-expiratory pressure of 5 cmH2O, and inspired oxygen fraction of 0.21. Respiratory system, lung and chest wall compliances (Crs, CL and Ccw, respectively) and resistances (Rrs, RL and Rcw, respectively), and the profile of the elastic pressure-volume curve (%E2) were evaluated. Arterial blood gases and volumetric capnography variables were collected. Comparisons between groups were performed by one-way ANOVA followed by Tukey-Kramer test for normally distributed data and with Kruskal-Wallis test followed by Steel-Dwass test for non-normally distributed data. Average Crs and CL in shunt lambs were 30% and 58% lower than in control, and 56% and 68% lower than in SHAM lambs, respectively. Ccw was 52% and 47% higher and Rcw was 53% and 40% lower in shunt lambs compared to controls and SHAMs, respectively. No difference in %E2 was identified between groups. No difference in respiratory mechanics was observed between control and SHAM lambs. In shunt lambs, Rcw, Crs and CL were decreased and Ccw was increased when compared to control and SHAM lambs. Pulmonary gas exchange did not seem to be impaired in shunt lambs when compared to controls and SHAMs.

Utility of Routine Head Ultrasounds in Infants on Extracorporeal Life Support: When is it Safe to Stop Scanning?

Intracranial hemorrhage (ICH) can be a devastating complication of extracorporeal life support (ECLS); however, studies on the timing of ICH detection by head ultrasound (HUS) are from 2 decades ago, suggesting ICH is diagnosed by day 5 of ECLS. Given advancements in imaging and critical care, our aim was to evaluate if the timing of ICH diagnosis in infants on ECLS support has changed. Patients <6 months old undergoing ECLS 2011-2020 at a tertiary care children's hospital were included. Primary outcome was timing of ICH diagnosis on HUS. Seventy-four infants underwent ECLS for cardiac (54%) or pulmonary (46%) indications. Venoarterial ECLS was most common (88%). Median ECLS duration was 6 days (range 1-26). Sixteen patients were diagnosed with ICH (21.6%), at a median of 2 days postcannulation (range 1-4). Nearly all were <4 weeks old at cannulation (93.8%). In conclusion, one-fifth of infants developed ICH diagnosed by HUS while on ECLS, all within the first 4 days of ECLS, consistent with previous literature. Despite advances in critical care and imaging technology, the temporality of ICH diagnosis in infants on ECLS is unchanged.

Total anomalous origin of the coronary arteries from the pulmonary artery: a systematic review.

BACKGROUND: Although rare, coronary artery anomalies can have significant clinical implications. Total anomalous origin of the coronary arteries from the pulmonary artery (TCAPA) represents a rare subtype of coronary artery anomaly for which little is known. The aim of this review was to characterise the presentation, utilised diagnostic modalities, associated cardiac lesions, and treatment strategies in patients with TCAPA. METHODS: A systematic review was performed for cases of TCAPA using PubMed, Embase, and Web of Science. Keywords searched included "total anomalous origin of the coronary arteries from the pulmonary artery," "single ostium anomalous coronary artery from the pulmonary artery," and "anomalous origin of both coronary arteries from the pulmonary artery." RESULTS: Fifty-seven cases of TCAPA were identified in 50 manuscripts. Fifty-eight per cent of patients were male and the median age at presentation was 10 days (mean 1.71 ± 6.6 years, range 0 days-39 years). Most patients were symptomatic at the time of presentation; cyanosis (n = 22) and respiratory distress (n = 14) were the most common symptoms. Cases were most commonly diagnosed at autopsy (n = 26, 45.6%), but operative intervention was pursued in 22 cases (45.6%); aortic re-implantation (n = 14) and a Takeuchi-type repair (n = 7) were the most common routes of repair. CONCLUSIONS: The clinical presentation of patients with TCAPA was found to be variable, likely related to the presence of associated cardiac lesions. TCAPA should be considered in patients with suspected anomalous origin of the left coronary artery from the pulmonary artery for the serious consequences that can occur if not promptly corrected.

HIF-1α promotes cellular growth in lymphatic endothelial cells exposed to chronically elevated pulmonary lymph flow.

Normal growth and development of lymphatic structures depends on mechanical forces created by accumulating interstitial fluid. However, prolonged exposure to pathologic mechanical stimuli generated by chronically elevated lymph flow results in lymphatic dysfunction. The mechanisms that transduce these mechanical forces are not fully understood. Our objective was to investigate molecular mechanisms that alter the growth and metabolism of isolated lymphatic endothelial cells (LECs) exposed to prolonged pathologically elevated lymph flow in vivo within the anatomic and physiologic context of a large animal model of congenital heart disease with increased pulmonary blood flow using in vitro approaches. To this end, late gestation fetal lambs underwent in utero placement of an aortopulmonary graft (shunt). Four weeks after birth, LECs were isolated and cultured from control and shunt lambs. Redox status and proliferation were quantified, and transcriptional profiling and metabolomic analyses were performed. Shunt LECs exhibited hyperproliferative growth driven by increased levels of Hypoxia Inducible Factor 1α (HIF-1α), along with upregulated expression of known HIF-1α target genes in response to mechanical stimuli and shear stress. Compared to control LECs, shunt LECs exhibited abnormal metabolism including abnormalities of glycolysis, the TCA cycle and aerobic respiration. In conclusion, LECs from lambs exposed in vivo to chronically increased pulmonary lymph flow are hyperproliferative, have enhanced expression of HIF-1α and its target genes, and demonstrate altered central carbon metabolism in vitro. Importantly, these findings suggest provocative therapeutic targets for patients with lymphatic abnormalities.

Minimizing the risk of occupational Q fever exposure: A protocol for ensuring Coxiella burnetii-negative pregnant ewes are used for medical research.

Q fever is a worldwide zoonosis caused by Coxiella burnetii that can lead to abortion, endocarditis, and death in humans. Researchers utilizing parturient domestic ruminants, including sheep, have an increased risk of occupational exposure. This study evaluated the effectiveness of our screening protocol in eliminating C. burnetii-positive sheep from our facility. From August 2010 to May 2018, all ewes (N = 306) and select lambs (N = 272; ovis aries) were screened twice for C. burnetii utilizing a serum Phase I and Phase II antibody immunofluorescence assay (IFA). The first screen was performed by the vendor prior to breeding, and the second screen was performed on arrival to the research facility. Ewes that were positive on arrival screening were quarantined and retested using repeat IFA serology, enzyme-linked immunosorbent assay, buffy coat polymerase chain reaction (PCR), and amniotic fluid PCR. The overall individual seroprevalence of C. burnetii in the flocks tested by the vendor was 14.2%. Ewes with negative Phase I and Phase II IFA results were selected for transport to the research facility. Upon arrival to the facility, two (0.7%) ewes had positive Phase I IFA results. Repeat testing demonstrated seropositivity in one of these two ewes, though amniotic fluid PCR was negative in both. The repeat seropositive ewe was euthanized prior to use in a research protocol. No Q fever was reported among husbandry, laboratory or veterinary staff during the study period. Serologic testing for C. burnetii with IFA prior to transport and following arrival to a research facility limits potential exposure to research staff.

Anomalous Origin of the Circumflex or Left Anterior Descending Artery From the Pulmonary Artery.

Anomalous origin of the circumflex or left anterior descending artery from the pulmonary artery (ACxAPA and ALADAPA, respectively) are rare congenital coronary anomalies with clinical presentation varying from an asymptomatic murmur to sudden cardiac arrest. A systematic review was performed, and 46 cases of ACxAPA and 51 cases of ALADAPA were identified in 87 articles. Data were collected and analyzed from each case. A better understanding of ACxAPA/ALADAPA can provide information to providers who encounter this lesion as well as provide insight into coronary artery development which may help in the understanding of coronary artery anomalies.

Mechanical forces alter endothelin-1 signaling: comparative ovine models of congenital heart disease.

The risk and progression of pulmonary vascular disease in patients with congenital heart disease is dependent on the hemodynamics associated with different lesions. However, the underlying mechanisms are not understood. Endothelin-1 is a potent vasoconstrictor that plays a key role in the pathology of pulmonary vascular disease. We utilized two ovine models of congenital heart disease: (1) fetal aortopulmonary graft placement (shunt), resulting in increased flow and pressure; and (2) fetal ligation of the left pulmonary artery resulting in increased flow and normal pressure to the right lung, to investigate the hypothesis that high pressure and flow, but not flow alone, upregulates endothelin-1 signaling. Lung tissue and pulmonary arterial endothelial cells were harvested from control, shunt, and the right lung of left pulmonary artery lambs at 3-7 weeks of age. We found that lung preproendothelin-1 mRNA and protein expression were increased in shunt lambs compared to controls. Preproendothelin-1 mRNA expression was modestly increased, and protein was unchanged in left pulmonary artery lambs. These changes resulted in increased lung endothelin-1 levels in shunt lambs, while left pulmonary artery levels were similar to controls. Pulmonary arterial endothelial cells exposed to increased shear stress decreased endothelin-1 levels by five-fold, while cyclic stretch increased levels by 1.5-fold. These data suggest that pressure or an additive effect of pressure and flow, rather than increased flow alone, is the principal driver of increased endothelin signaling in congenital heart disease. Defining the molecular drivers of the pathobiology of pulmonary vascular disease due to differing mechanical forces will allow for a more targeted therapeutic approach.

Anomalous Origin of the Right Coronary Artery From the Pulmonary Artery: A Systematic Review.

BACKGROUND: Anomalous origin of the right coronary artery from the pulmonary artery (ARCAPA) is a rare congenital cardiac lesion that has been diagnosed in both children and adults with symptoms ranging from an asymptomatic murmur to sudden cardiac death. The aim of this review was to characterize published cases of ARCAPA to better understand this rare congenital coronary anomaly. METHODS: A systematic review was performed using PubMed, Embase, and Google Scholar for cases of ARCAPA. Keywords searched included: "anomalous origin of the right coronary artery from the pulmonary artery" and "ARCAPA." RESULTS: A total of 223 cases of ARCAPA were identified in 193 case reports. There was a slight male predominance (54.5%) and the median age at presentation was 14.0 years. Thirty-eight percent of patients were asymptomatic and most commonly identified during evaluation of a murmur. Angina and dyspnea were the most common presenting symptoms (22.4% and 17.0%, respectively). In symptomatic patients, a bimodal distribution of age at presentation was observed with a peak near birth and another between ages 40 and 60 years. The condition was most commonly diagnosed with coronary angiography (40.4%). Most cases were repaired surgically (72.6%) and reimplantation of the right coronary artery onto the aorta was the most common method of repair (62.3%). CONCLUSIONS: ARCAPA represents a rare coronary anomaly with great variability in clinical presentation. An understanding of the pathophysiology associated with the lesion is critical when determining treatment strategies.

Left Ventricle to Right Atrial Shunt Associated With Ventricular-Atrial Malalignment, Double Outlet Right Atrium, and Subaortic Membrane.

We describe an asymptomatic 7-year-old boy who was taken to the operating room for repair of a subaortic membrane and possible Gerbode's defect. He was found to have a double outlet right atrium associated with an accessory atrioventricular valve in addition to a small atrial septal defect and subaortic membrane. Regurgitant flow through this accessory valve led to the left ventricle to right atrial shunt that was seen on preoperative ECHO. The atrial septal defect was repaired and a baffle was used to isolate blood flow across the accessory valve from the left atrium to the left ventricle. The patient was discharged on postoperative day 4 and has been doing well 2 years postoperatively.

Ovine Models of Congenital Heart Disease and the Consequences of Hemodynamic Alterations for Pulmonary Artery Remodeling.

The natural history of pulmonary vascular disease associated with congenital heart disease (CHD) depends on associated hemodynamics. Patients exposed to increased pulmonary blood flow (PBF) and pulmonary arterial pressure (PAP) develop pulmonary vascular disease more commonly than patients exposed to increased PBF alone. To investigate the effects of these differing mechanical forces on physiologic and molecular responses, we developed two models of CHD using fetal surgical techniques: 1) left pulmonary artery (LPA) ligation primarily resulting in increased PBF and 2) aortopulmonary shunt placement resulting in increased PBF and PAP. Hemodynamic, histologic, and molecular studies were performed on control, LPA, and shunt lambs as well as pulmonary artery endothelial cells (PAECs) derived from each. Physiologically, LPA, and to a greater extent shunt, lambs demonstrated an exaggerated increase in PAP in response to vasoconstricting stimuli compared with controls. These physiologic findings correlated with a pathologic increase in medial thickening in pulmonary arteries in shunt lambs but not in control or LPA lambs. Furthermore, in the setting of acutely increased afterload, the right ventricle of control and LPA but not shunt lambs demonstrates ventricular-vascular uncoupling and adverse ventricular-ventricular interactions. RNA sequencing revealed excellent separation between groups via both principal components analysis and unsupervised hierarchical clustering. In addition, we found hyperproliferation of PAECs from LPA lambs, and to a greater extent shunt lambs, with associated increased angiogenesis and decreased apoptosis in PAECs derived from shunt lambs. A further understanding of mechanical force-specific drivers of pulmonary artery pathology will enable development of precision therapeutics for pulmonary hypertension associated with CHD.

Analysis of the microRNA signature driving adaptive right ventricular hypertrophy in an ovine model of congenital heart disease.

The right ventricular (RV) response to pulmonary arterial hypertension (PAH) is heterogeneous. Most patients have maladaptive changes with RV dilation and RV failure, whereas some, especially patients with PAH secondary to congenital heart disease, have an adaptive response with hypertrophy and preserved systolic function. Mechanisms for RV adaptation to PAH are unknown, despite RV function being a primary determinant of mortality. In our congenital heart disease ovine model with fetally implanted aortopulmonary shunt (shunt lambs), we previously demonstrated an adaptive physiological RV response to increased afterload with hypertrophy. In the present study, we examined small noncoding microRNA (miRNA) expression in shunt RV and characterized downstream effects of a key miRNA. RV tissue was harvested from 4-wk-old shunt and control lambs ( n = 5), and miRNA, mRNA, and protein were quantitated. We found differential expression of 40 cardiovascular-specific miRNAs in shunt RV. Interestingly, this miRNA signature is distinct from models of RV failure, suggesting that miRNAs might contribute to adaptive RV hypertrophy. Among RV miRNAs, miR-199b was decreased in the RV with eventual downregulation of nuclear factor of activated T cells/calcineurin signaling. Furthermore, antifibrotic miR-29a was increased in the shunt RV with a reduction of the miR-29 targets collagen type A1 and type 3A1 and decreased fibrosis. Thus, we conclude that the miRNA signature specific to shunt lambs is distinct from RV failure and drives gene expression required for adaptive RV hypertrophy. We propose that the adaptive RV miRNA signature may serve as a prognostic and therapeutic tool in patients with PAH to attenuate or prevent progression of RV failure and premature death. NEW & NOTEWORTHY This study describes a novel microRNA signature of adaptive right ventricular hypertrophy, with particular attention to miR-199b and miR-29a.

KLF2-mediated disruption of PPAR-γ signaling in lymphatic endothelial cells exposed to chronically increased pulmonary lymph flow.

Lymphatic abnormalities associated with congenital heart disease are well described, yet the underlying mechanisms remain poorly understood. Using a clinically relevant ovine model of congenital heart disease with increased pulmonary blood flow, we have previously demonstrated that lymphatic endothelial cells (LECs) exposed in vivo to chronically increased pulmonary lymph flow accumulate ROS and have decreased bioavailable nitric oxide (NO). Peroxisome proliferator-activated receptor-γ (PPAR-γ), which abrogates production of cellular ROS by NADPH oxidase, is inhibited by Krüppel-like factor 2 (KLF2), a flow-induced transcription factor. We hypothesized that chronically increased pulmonary lymph flow induces a KLF2-mediated decrease in PPAR-γ and an accumulation of cellular ROS, contributing to decreased bioavailable NO in LECs. To better understand the mechanisms that transduce the abnormal mechanical forces associated with chronically increased pulmonary lymph flow, LECs were isolated from the efferent vessel of the caudal mediastinal lymph node of control ( n = 5) and shunt ( n = 5) lambs. KLF2 mRNA and protein were significantly increased in shunt compared with control LECs, and PPAR-γ mRNA and protein were significantly decreased. In control LECs exposed to shear forces in vitro, we found similar alterations to KLF2 and PPAR-γ expression. In shunt LECs, NADPH oxidase subunit expression was increased, and bioavailable NO was significantly lower. Transfection of shunt LECs with KLF2 siRNA normalized PPAR-γ, ROS, and bioavailable NO. Conversely, pharmacological inhibition of PPAR-γ in control LECs increased ROS equivalent to levels in shunt LECs at baseline. Taken together, these data suggest that one mechanism by which NO-mediated lymphatic function is disrupted after chronic exposure to increased pulmonary lymph flow is through altered KLF2-dependent PPAR-γ signaling, resulting in increased NADPH oxidase activity, accumulation of ROS, and decreased bioavailable NO. NEW & NOTEWORTHY Lymphatic endothelial cells, when exposed in vivo to chronically elevated pulmonary lymph flow in a model of congenital heart disease with increased pulmonary blood flow, demonstrate Krüppel-like factor 2-dependent disrupted peroxisome proliferator-activated receptor-γ signaling that results in the accumulation of reactive oxygen species and decreased bioavailable nitric oxide.

Subcutaneous local anesthetic infusion could eliminate use of epidural analgesia after the Nuss procedure.

AIM: To compare outcomes of continuous subcutaneous infusion of local anesthetic and epidural analgesia following the Nuss procedure. PATIENTS & METHODS: A retrospective chart review compared patients managed with subcutaneous local anesthetic infusion (n = 12) versus thoracic epidural (n = 19) following the Nuss procedure from March 2013 to June 2015. RESULTS: There was no difference in hospital length of stay or days on intravenous narcotics. Epidural catheter placement prolonged operating room time (146.58 ± 28.30 vs 121.42 ± 21.98 min, p = 0.01). Average pain scores were slightly higher in the subcutaneous infusion group (3.72 ± 1.62 vs 2.35 ± 0.95, p = 0.02), but of negligible clinical significance. CONCLUSION: Continuous subcutaneous infusion of local anesthetic could eliminate the need for thoracic epidural for pain management after the Nuss procedure.

Magnetic Mini-Mover Procedure for pectus excavatum IV: FDA sponsored multicenter trial.

PURPOSE: The Magnetic Mini-Mover Procedure (3MP) is a minimally invasive treatment for prepubertal patients with pectus excavatum. This multicenter trial sought to supplement safety and efficacy data from an earlier pilot trial. METHODS: Fifteen patients with pectus excavatum had a titanium-enclosed magnet implanted on the sternum. Externally, patients wore a custom-fitted magnetic brace. Patients were monitored closely for safety. Efficacy was determined by the Haller Index (HI) and satisfaction surveys. After 2 years, the implant was removed. RESULTS: Mean patient age was 12 years (range 8-14), and mean pretreatment HI was 4.7 (range 3.6-7.4). The device was successfully implanted in all patients. Mean treatment duration was 25 months (range 18-33). Posttreatment chest imaging in 13 patients indicated that HI decreased in 5, remained stable in 2, and increased in 6. Seven out of 15 patients had breakage of the implant's titanium cables because of fatigue fracture. Eight out of 13 patients were satisfied with their chest after treatment. CONCLUSION: The 3MP is a safe, minimally invasive, outpatient treatment for prepubertal patients with pectus excavatum. However, the magnetic implant design led to frequent device breakage, confounding analysis. The HI indicated mixed efficacy, although surveys indicated most patients perceived a benefit. STUDY TYPE/LEVEL OF EVIDENCE: Case series, treatment study. Level IV.

Novel application of a percutaneous left ventricular assist device as a bridge to transplant in a paediatric patient with severe heart failure due to viral myocarditis.

A 13-year obese female with suspected viral myocarditis presented with acute decompensated heart failure. Due to her body habitus, she was a poor candidate for immediate heart transplantation. A peripherally inserted left ventricular assist device (LVAD) was implanted via the right axillary artery. Following device insertion the patient experienced rapid improvement in symptoms. The LVAD provided effective left ventricular unloading for 50 days, promoting myocardial recovery and maintaining excellent patient performance status. The device placement strategy allowed for a high level of activity including completion of school-work and participation in a weight loss program. The patient achieved a 28-pound weight loss, thus improving candidacy for transplantation. Removal of the device was well tolerated and post-removal echocardiography revealed an improvement in the left ventricular ejection fraction (LVEF) from 21% at baseline to 38% after device removal. This case represents a successful application of a peripherally inserted LVAD as a bridge to transplant in a pediatric patient with severe heart failure due to suspected viral myocarditis. For select patients with this condition, a transaxillary LVAD should be considered as a therapeutic option as it is well tolerated and provides effective left ventricle unloading to promote myocardial recovery and maintain performance status.

Intercostal nerve cryoablation versus thoracic epidural catheters for postoperative analgesia following pectus excavatum repair: Preliminary outcomes in twenty-six cryoablation patients.

BACKGROUND: Multimodal pain management strategies are used for analgesia following pectus excavatum repair. However, the optimal regimen has not been identified. We describe our early experience with intercostal cryoablation for pain management in children undergoing the Nuss procedure and compare early cryoablation outcomes to our prior outcomes using thoracic epidural analgesia. METHODS: A multi-institutional, retrospective review of fifty-two patients undergoing Nuss bar placement with either intercostal cryoablation (n=26) or thoracic epidural analgesia (n=26) from March 2013 to January 2016 was conducted. The primary outcome was hospital length of stay. Secondary outcomes included telemetry unit monitoring time, total intravenous narcotic use, duration of intravenous narcotic use, and postoperative complications. RESULTS: Patients who underwent intercostal cryoablation had a significant reduction in the mean hospital length of stay, time in a monitored telemetry bed, total use of intravenous narcotics, and the duration of intravenous narcotic administration when compared to thoracic epidural patients. Cryoablation patients had a slightly higher rate of postoperative complications. CONCLUSION: Intercostal cryoablation is a promising technique for postoperative pain management in children undergoing repair of pectus excavatum. This therapy results in reduced time to hospital discharge, decreased intravenous narcotic utilization, and has eliminated epidurals from our practice. LEVEL OF EVIDENCE: Retrospective study - level III.