Renal function after ductus arteriosus transcatheter closure with or without angiography in very preterm infants.

AIM: Transcatheter closure of the patent ductus arteriosus (TCPDA) is increasingly used in preterm infants as an alternative to surgical ligation. However, clinically ill preterm infants are at risk of contrast nephropathy due to the angiography contrast agents used during the procedure. METHODS: We performed a single-centre before-and-after comparative study in VLBW infants to compare the kinetics of serum creatinine during the first 4 days after TCPDA with or without angiography. RESULTS: 69 patients were included and divided into two groups: TCPDA with (contrast+; n = 37) and without (contrast-, n = 32) use of contrast agent. The median dose [range] of contrast agent was 1.0 mL/kg [0.6-2.4 mL/kg]. The change in serum creatinine level between day 2 to 4 after TCPCA and baseline decreased in the contrast- group (-17% [-46%; 18%]), while it increased in the contrast+ group (7% [-24%; 202%] p = 0.002). Comparison of blood urea levels between groups showed similar significant differences. The change in serum creatinine between day 2 to 4 and baseline was significantly correlated with the dose of contrast agent (r2 = 0.682; p < 0.001). CONCLUSION: The use of contrast agents during TCPDA can potentially harm the renal function of very preterm infants. Therefore, we advise minimising or avoiding the use of contrast agents.

Upfront triple combination therapy in severe paediatric pulmonary arterial hypertension.

Treatment strategies in paediatric pulmonary arterial hypertension (PAH) have evolved over the last years, but survival is still poor. Recently, in adults with severe PAH, upfront triple combination therapy (uTCT) from diagnosis has been reported to show significant clinical improvement and excellent long-term outcome. This retrospective, observational study aimed to assess the efficacy of uTCT in paediatric PAH.Children diagnosed with PAH between 2010 and 2019 and started with uTCT were included. World Health Organization Functional Class (WHO-FC), haemodynamics, echocardiography, 6-min walking distance and serum level of N-terminal pro-brain-natriuretic-peptide were assessed at baseline, after 3 and 6 months and at last available follow-up. Events were defined as death, lung transplantation or Potts shunt.21 children (median age 4.8 years (2.5-12.8), 57% females) were included. All children except one were in WHO-FC III or IV (28% and 67%, respectively). After 3 months, one child had died and one child had received a Potts shunt. The remaining 19 children showed clinical and echocardiographic improvement, which persisted at 6 months. Children with idiopathic and heritable PAH showed one-, two- and three-year transplant-free survival estimates of 100%, 94% and 87%, albeit 47% of them receiving a Potts shunt during follow-up.Children with severe PAH, but not pulmonary veno-occlusive disease, improved significantly with uTCT and showed beneficial up to 3-year survival rates, albeit 47% of them receiving a Potts shunt during follow-up. The role of a Potts shunt in conjunction to uTCT in paediatric PAH needs to be further established.

Pulmonary hypertension after bone marrow transplantation in children.

INTRODUCTION: Pulmonary hypertension is a rare but important cause of mortality after haematopoietic stem cell transplantation (HSCT) in children. This complication is poorly characterised in the literature. We report here a series of children who developed pulmonary hypertension after HSCT. METHODS: Between January 2008 and December 2015, we retrospectively analysed 366 children who underwent HSCT (age range 0.5-252 months; median 20.3 months). During the post-HSCT course, echocardiography scans motivated by respiratory symptoms identified 31 patients with elevated tricuspid regurgitation velocity (>2.8 m·s-1), confirmed when possible by right heart catheterisation (RHC). RESULTS: 22 patients had confirmed pulmonary hypertension with mean±sd pulmonary arterial pressure 40.1±10 mmHg (range 28-62 mmHg) and pulmonary vascular resistance 17.3±9.2 Wood Units (range 8-42 Wood Units). Among the 13 responders at reactivity test, only one patient responded to calcium channel blockers. Seven patients (32%) died. 15 pulmonary hypertension patients were alive after a mean±sd follow-up of 6.5±2.3 years (range 2-10 years). All survivors could be weaned off pulmonary hypertension treatment after a median follow-up of 5 months (range 3-16). The delay between clinical symptoms and initiation of pulmonary hypertension therapy was significantly longer in patients who subsequently died (mean±sd 33.5±23 days; median 30 days) than in survivors (mean±sd 7±3 days) (p<0.001). CONCLUSION: Pulmonary hypertension is a severe complication of HSCT with an underestimated incidence and high mortality. Aggressive and timely up-front combination therapy allowed normalisation of pulmonary pressure and improved survival.

Cardiac catheterisation in infants weighing less than 2500 grams.

OBJECTIVES: The aim of the study was to report the outcome of cardiac catheterisation in low-weight patients. BACKGROUND: Data regarding cardiac catheterisation in infants weighing <2500 g are scarce. METHODS: We reviewed all cardiac catheterisations performed in infants weighing <2500 g between January 2000 and May 2016. An analysis with respect to the type of procedure, the complexity of procedure (procedure type risk), and haemodynamic vulnerability index was finally carried out. We report the occurrence of deaths and complications using the adverse event severity score. RESULTS: A total of 218 procedures were performed on 211 patients. The mean age and weight were, respectively, 15 ± 26 days (range, 0-152) and 2111 ± 338 g (range, 1000-2500). Procedures were interventional and diagnostic, respectively, in 174 (80%) and 44 (20%) patients. Out of 218, 205 (94%) were successful. Eleven complications (5%) occurred - six with an adverse event severity score of 4 and five with an adverse event severity score of 3. Ten patients (91%) showed a favourable outcome, and one died (stent thrombosis few hours after patent ductus arteriosus stenting). No correlation was found between lower weight and occurrence of death (p = 0.68) or complications (p = 0.23). The gravity scores (procedure type risk and haemodynamic vulnerability index) were not predictive of complications. CONCLUSIONS: Cardiac catheterisation in infants weighing <2500 g appears feasible and effective with low risk. The weight should not discourage from performing cardiac catheterisation in this population.

Genetic analyses in a cohort of children with pulmonary hypertension.

The prevalence of germline mutations in paediatric pulmonary hypertension (PH) is poorly documented. The objective of this study was to determine the mutation frequency in PH genes in a paediatric cohort and describe the clinical characteristics of mutation carriers.The study involved 66 index cases with PH: 35 children with idiopathic pulmonary arterial hypertension (IPAH); five children with familial PAH (FPAH); three children with pulmonary veno-occlusive disease (PVOD); and 23 children with PAH associated with congenital heart disease (APAH-CHD).No mutations were found in the 23 children with APAH-CHD. In the 40 children with IPAH or FPAH, 12 mutations were found: five on BMPR2; four on ACVRL1; and three on TBX4. In the three PVOD cases, two carried the EIF2AK4 mutation. Mutation carriers had a more severe disease at diagnosis and more aggressive first-line therapy was required. The three patients with PVOD had a very severe disease at diagnosis and required a lung transplantation.The genetic architecture of paediatric PAH is enriched in ACVRL1 and TBX4 mutations compared to adult PAH, but further studies are required to confirm these results. Childhood-onset PAH in children carrying a mutation in one of the genes tested has a more severe presentation at diagnosis but a similar outcome to that observed in non-carriers.

Monitoring of Hemodynamics With Right Heart Catheterization in Children With Pulmonary Arterial Hypertension.

Background Right heart catheterization (RHC) is a high-risk procedure in children with pulmonary arterial hypertension without clear guidelines for the indications and targets of invasive reassessment. Our objectives are to define the aims of repeated RHC and evaluate the correlation between noninvasive criteria and hemodynamic parameters. Methods and Results Clinical and hemodynamic characteristics from 71 incident treatment-naïve children (median age 6.2 years) with pulmonary arterial hypertension who had a baseline and reevaluation RHC were analyzed. Correlations between noninvasive predictors and hemodynamic parameters were tested. Adverse outcomes were defined as death, lung transplantation, or Potts shunt. At baseline, pulmonary vascular resistance index (hazard ratio [HR] 1.07 per 1 WU·m2 increase [95% CI, 1.02-1.12], P=0.002), stroke volume index (HR 0.95 per 1 L·min-1·m-2 increase [95% CI, 0.91-0.99], P=0.012), pulmonary artery compliance index (HR 0.16 per 1 mL·mm Hg-1·m-2 increase [95% CI, 0.051-0.52], P=0.002), and right atrial pressure (HR, 1.31 per 1 mm Hg increase [95% CI, 1.01-1.71], P=0.043) were associated with adverse outcomes. Pulmonary vascular resistance index, pulmonary artery compliance index, and right atrial pressure were still associated with a worse outcome at second RHC. Noninvasive criteria accurately predicted hemodynamic evolution; however, 70% of the patients who had improved based on noninvasive criteria still presented at least 1 "at risk" hemodynamics at second RHC. Conclusions Pulmonary vascular resistance index, pulmonary artery compliance index, and right atrial pressure are solid predictors of adverse outcomes in pediatric pulmonary arterial hypertension and potential therapeutic targets. Noninvasive criteria accurately predict the evolution of hemodynamic parameters, but insufficiently. Repeated RHC are helpful to identify children with persistent higher risk after treatment introduction.

Multifactorial pulmonary hypertension in infantile scimitar syndrome.

BACKGROUND: Pulmonary hypertension in infantile scimitar syndrome is highly prevalent at diagnosis, and has a multifactorial origin. AIMS: To analyse the constellation of anatomical anomalies and initial physiology, and their contribution to pulmonary hypertension and outcome in infantile scimitar syndrome. METHODS: Pulmonary hypertension causes were classified into five categories: associated with systemic supply to the right lung; associated with left-to-right shunt; postcapillary; related to respiratory or developmental lung disease; and "idiopathic-like" pulmonary arterial hypertension. Co-morbidities contributing to pulmonary hypertension were also classified according to the World Symposium on Pulmonary Hypertension (WSPH) and Panama classifications. RESULTS: Of 111 patients, 64 had pulmonary hypertension; 24 patients had one cause of pulmonary hypertension, 23 had two potential causes and 17 had at least three potential causes. Co-morbidities contributing to pulmonary hypertension described the multifactorial origin in>80% of patients, with associated congenital heart disease being the main contributor. Mortality was 41% in patients with and 7% in patients without pulmonary hypertension. The proportions of deaths among patients with one, two or more than two causes of pulmonary hypertension were similar. Eight of 38 survivors had persisting pulmonary hypertension at last follow-up. The risk of death was associated pulmonary hypertension at diagnosis (P=0.002) and the presence of an associated congenital heart disease requiring surgical repair (P=0.039). CONCLUSIONS: Scimitar syndrome is an archetypal example of multifactorial causes of pulmonary hypertension, with associated congenital heart disease and pulmonary vascular anomalies being the main contributors. Infants with scimitar syndrome require accurate phenotyping to guide management and predict outcome.

Long-term outcomes of transcatheter Potts shunt in children with suprasystemic pulmonary arterial hypertension.

Background: Transcatheter Potts shunt (TPS) is a palliation alternative for children with severe pulmonary arterial hypertension (PAH). Debates on the long-term outcomes remain unsolved. Objectives: To evaluate long-term clinical and procedural outcomes of TPS intervention. Methods: Single-center retrospective data review of children with severe PAH who had TPS between 2009 and 2018. Patients who died per-operatively and early post-procedure were excluded. Long-term outcomes of survivors were evaluated. Results: Out of 13 identified patients (53.8% males), 7 had endovascular stenting of probe/patent arterial ducts, while 6 individuals had aorta-to-pulmonary radiofrequency perforation and covered stent placement. Compared to baseline, the overall clinical condition significantly improved at discharge (p < 0.001) and stayed better at the last visit (p < 0.05) despite frequent clinical worsening events across follow-up. Improvement in functional class across follow-up was significant (p < 0.001). There was, however, no significant improvement in other disease markers (TPASE, 6MWD z-scores, and NT-proBNP levels) or reduction in PAH medications. The median follow-up was 77.4 months (IQR, 70.7-113.4). Survival was 100% at 1 year and 92.3% at 6 years. Freedom from reinterventions was 77% at 1 year and 21% at 6 years. Nine (69.2%) patients had stent reinterventions at a median of 25 months (IQR, 9.5-56) postoperative. Balloon dilatation and restenting were performed in 53.8% and 46.2% of patients, respectively. High-pressure post-dilatation of implanted stents was performed in 53.8% of patients during TPS intervention for incomplete stent expansion and/or residual pressure gradient and was associated with higher rates of reinterventions (p = 0.021). Stent malfunctioning was present in 46.2% of patients at last follow-up. Two patients are listed for heart-lung transplantation. Conclusion: Survivors of TPS procedures experience significant improvement in functional class that can be durable. Clinical worsening and stent malfunctioning are frequent morbid events indicating recurrent transcatheter reinterventions throughout follow-up. Six-year survival is, however, satisfactory.

Transcatheter patent arterial duct closure in premature infants: A new technique to ease access to the patent arterial duct, with particular benefit for the tricuspid valve.

BACKGROUND: Transcatheter patent arterial duct (PAD) closure in premature infants has been shown to be feasible. Since our early transcatheter PAD closure procedures in premature infants at Hôpital Necker Enfants Malades, we have changed our technique several times to advance the guidewire through the right heart to avoid tricuspid valve damage. AIM: To describe the technique we have been using since May 2019, to report our results with a particular focus on tricuspid leaks and to analyse the potential mechanisms of tricuspid lesion development with previous methods. METHODS: All premature infants weighing<2kg who underwent transcatheter PAD closure with this new technique were included. Demographic data, procedural data, outcome and procedural complications were reviewed, with particular attention to the occurrence of tricuspid regurgitation. RESULTS: Between May 2019 and May 2020, 33 patients were included. Median gestational age was 25 weeks. Median birth weight and procedural weight were 690g (range 490-1065g; interquartile range [IQR] 620-785g) and 1160g (range 900-1900g; IQR 1030-1300g), respectively. Median age at procedure was 35 (IQR 30-46) days. PAD anatomy was evaluated on transthoracic echocardiography only. The median duct diameter was 3 (IQR 2.5-3.2) mm at the pulmonary end. Success rate was 100% (defined as successful closure without residual shunt). One patient had a renal vein thrombosis, which fully resolved with low-molecular-weight heparin anticoagulation. No tricuspid regurgitation or stenosis of the left pulmonary artery or the aorta was seen. One patient died of a superior caval vein obstruction with bilateral chylothorax related to a central catheter thrombosis 56 days after the procedure, unrelated to the catheter procedure. CONCLUSION: In this prospective study, we describe a new technique to avoid tricuspid valve damage and facilitate delivery of the PAD device.

Potts anastomosis in children with severe pulmonary arterial hypertension and atrial septal defect.

AIMS: Potts shunt has been proposed as a bridge or alternative to lung transplantation for children with severe and drug-refractory suprasystemic pulmonary arterial hypertension (PAH). We describe the management of the atrial shunt when a Potts shunt is planned in refractory PAH. METHODS AND RESULTS: We report a case series of children in whom a Potts shunt was done for severe PAH associated with an atrial septal defect to illustrate the different clinical and haemodynamic scenarios. Five children (2 to 13 years) underwent a Potts shunt: three surgical, one percutaneous Potts shunt, and one percutaneous stenting of a restrictive arterial duct. All had associated atrial septal defect. Those who had generalized cyanosis before the procedure had a complicated postoperative course and required longer ventilatory and inotropic support, except the one who had atrial septal defect closure before the Potts shunt. One of the three cyanotic patients died. Two patients with left-to-right shunt before the Potts shunt had an uncomplicated postoperative course. CONCLUSIONS: Shunt physiology is only partially predictable after the Potts shunt in children with PAH and atrial septal defect. Abrupt drop in left ventricle preload while the right ventricle is decompressed can potentially be prevented by atrial septal defect closure prior to the Potts shunt.

Spontaneous Closure of the Arterial Duct after Transcatheter Closure Attempt in Preterm Infants.

(1) Background: Transcatheter closure of the patent arterial duct (TCPDA) in preterm infants is an emerging procedure. Patent arterial duct (PDA) spontaneous closure after failed TCPDA attempts is seen but reasons and outcomes are not reported; (2) Methods: We retrospectively included all premature infants <2 kg with abandoned TCPDA procedures from our institutional database between September 2017 and August 2021. Patients' data and outcomes were reviewed; (3) Results: The procedure was aborted in 14/130 patients referred for TCPDA. Two patients had spasmed PDA upon arrival in the catheterization laboratory and had no intervention. One patient had ductal spasm after guidewire cross. Four patients had unsuitable PDA size/shape for closure. In seven patients, device closure was not possible without causing obstruction on adjacent vessels. Among the 12 patients with attempted TCPDA, five had surgery on a median of 3 days after TCPDA and seven had a spontaneous PDA closure within a median of 3 days after the procedure. Only the shape of the PDA differed between the surgical ligation group (short and conical) and spontaneous closure group (F-type); (4) Conclusions: In the case of TCPDA failure, mechanically induced spontaneous closure may occur early after the procedure. Surgical ligation should be postponed when clinically tolerated.

Treprostinil treatment decreases circulating platelet microvesicles and their procoagulant activity in pediatric pulmonary hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) results from pulmonary vascular disease and may eventually lead to right heart failure and death. Vasodilator therapy has greatly improved PAH prognosis. Circulating microvesicles are considered as surrogate markers of endothelial and hematopoietic cell activation. AIM: Thus, our purpose was to determine if MVs are upregulated in pediatric PAH such as reported in adult patients, and to analyze the impact of vasodilator therapies on MV count and function. PATIENTS: Population study consisted of 26 patients of median age 6.09 years, with Congenital Heart Disease (CHD) and elevated pulmonary vascular resistance (CHD-PAH) or idiopathic PAH (iPAH). RESULTS: Compared to healthy controls, all circulating MV subpopulations were found higher in untreated PAH patients. No significant differences of annexin-V+ total MV, endothelial, or leukocyte derived-MV counts were found between untreated patients and those receiving oral vasodilator therapies. Conversely, platelet MVs were significantly lower in the group treated with SC-treprostinil compared with both untreated PAH and oral therapy groups (P = 0.01), and exhibited a significant decrease of phospholipid procoagulant activity. Control samples treated in vitro with treprostinil at therapeutic concentrations showed as expected a significant decrease of platelet aggregation but also a reduced spontaneous MV generation. CONCLUSION: Our results suggest that treprostinil, besides vasodilation, might exert its beneficial effect through an inhibition of platelet activation, resulting in a decreased number and procoagulant activity of circulating MVs.

Endothelial-dependent vasodilation is impaired in children with sickle cell disease.

Impairment of endothelial-dependent vasodilation has been demonstrated in adults with sickle cell anemia (SCA). We enrolled 21 SCA children, mean age 10.4+/-3.3 yrs, and 23 Afro-Caribbean controls. We examined flow-mediated (FMD) and nitroglycerine-mediated (GTNMD) dilation of the brachial artery, using echotracking techniques, and measured intima-media thickness (IMT) and mechanical properties of the common carotid artery. FMD was significantly decreased in SCA children vs controls (5.6+/-0.2 vs 8.0+/-0.2%, p=0.008), while IMT, stiffness of the common carotid artery, and GTNMD were comparable. In conclusion, endothelial dysfunction is present as early as childhood in SCA patients.

Arterial stiffness and endothelial dysfunction in HIV-infected children.

BACKGROUND: The role of antiretroviral therapy in acceleration of atherosclerosis in HIV-infected adults is controversial, partly because of the confounding effects of the involvement of classic cardiovascular risk factors. OBJECTIVE: To study vascular function in HIV-infected children. DESIGN: Cross-sectional study of 49 HIV-infected children (34 receiving antiretroviral therapy and 15 never treated) and if 24 age- and sex-matched controls. METHODS: Automatic, computerized, ultrasonic procedure evaluation of geometric and mechanical properties of the common carotid artery, and of the endothelium-dependent dilation and endothelium-independent dilation. RESULTS: Relative systolodiastolic variations in diameter of the carotid artery in HIV-infected children were significantly lower than those in controls, but there was no significant difference in intima-media thickness. Cross-sectional compliance and distensibility were also significantly lower. Wall stiffness, assessed as the incremental elastic modulus, was larger in HIV-infected children. Endothelium-dependent dilation was lower in HIV-infected children but non-endothelium-dependent dilation was similar to that in controls. We did not find differences for any of the vascular variables between HIV-infected children receiving antiretroviral therapy and those never treated. All arterial variables were similar in children with and without dyslipidemia. CONCLUSIONS: HIV-infected children had a vascular dysfunction in the absence of cardiovascular risk factors. In this short series, no additional detrimental effects were observed after a mean of 5 years of antiretroviral therapy.

Kinetics of the utilization of dietary arginine for nitric oxide and urea synthesis: insight into the arginine-nitric oxide metabolic system in humans.

BACKGROUND: The systemic availability of oral/dietary arginine and its utilization for nitric oxide (NO) synthesis remains unknown and may be related to a competitive hydrolysis of arginine into urea in the splanchnic area and systemic circulation. OBJECTIVES: We investigated the kinetics and dose-dependency of dietary arginine utilization for NO compared with urea synthesis and studied the characteristics of the arginine-NO metabolic system in healthy humans. DESIGN: We traced the metabolic fate and analyzed the utilization dynamics of dietary arginine after its ingestion at 2 nutritional amounts in healthy humans (n = 9) in a crossover design by using [(15)N-(15)N-(guanido)]-arginine, isotope ratio mass spectrometry techniques, and data analysis with a compartmental modeling approach. RESULTS: Whatever the amount of dietary arginine, 60 ± 3% (±SEM) was converted to urea, with kinetics indicative of a first-pass splanchnic phenomenon. Despite this dramatic extraction, intact dietary arginine made a major contribution to the postprandial increase in plasma arginine. However, the model identified that the plasma compartment was a very minor (~2%) precursor for the conversion of dietary arginine into NO, which, in any case, was small (<0.1% of the dose). The whole-body and plasma kinetics of arginine metabolism were consistent with the suggested competitive metabolism by the arginase and NO synthase pathways. CONCLUSIONS: The conversion of oral/dietary arginine into NO is not limited by the systemic availability of arginine but by a tight metabolic compartmentation at the systemic level. We propose an organization of the arginine metabolic system that explains the daily maintenance of NO homeostasis in healthy humans.

Vascular remodeling after "successful" repair of coarctation: impact of aortic arch geometry.

OBJECTIVES: This study was designed to investigate the influence of aortic arch geometry on vascular remodeling after anatomically successful repair of coarctation of the aorta (CoA). BACKGROUND: Abnormalities of the precoarctation vasculature are known to occur after CoA repair and appear related to adverse outcomes. The influence of aortic arch geometry on such abnormalities is unknown. METHODS: Sixty-three postcoarctectomy subjects (age 15.9 +/- 6.3 years) were compared with 63 control volunteers. Aortic arch shape was characterized on magnetic resonance imaging using both qualitative classification, identifying 3 subtypes of arch geometry (Gothic, Crenel, Romanesque), and a quantitative index, height/width ratio (H/W) of the aorta. Using ultrasound, we measured carotid artery intima-media thickness (IMT) and stiffness index and distensibility, as well as right brachial artery flow-mediated dilation (FMD) and glyceryl trinitate (GTN)-induced dilatation, to assess the precoarctation vasculature of these subjects. RESULTS: Gothic arch type was associated with higher carotid IMT and stiffness index, lower carotid distensibility (p < 0.001 for all), and lower brachial reactivity (FMD, p < 0.01; GTN response, p < 0.001) compared with Crenel and Romanesque geometries and with control subjects. The height/width ratio was also significantly related to these vascular abnormalities. Even in CoA subjects with Romanesque arch geometry, arterial function and stiffness parameters were significantly impaired compared with control subjects. CONCLUSIONS: In young adult survivors of anatomically successful CoA repair, a gothic-type aortic arch with high H/W is associated with abnormal IMT, higher aortic stiffness index, and impaired arterial reactivity in the pre-CoA vasculature.

Meal amino acids with varied levels of arginine do not affect postprandial vascular endothelial function in healthy young men.

Postprandial endothelial dysfunction is a key event mediating the effects of diet on early atherogenesis. The potential effects of protein intake have been overlooked in the past, although amino acids are precursors for homocysteine and nitric oxide (NO). Our objective was to study the effect of amino acids on postprandial vascular function, in relation to the utilization of meal arginine for NO production. In a crossover design, 9 men ingested 50 g of a complete amino acid mixture, trace-labeled with (13)C-glycine and (15)N(2)-arginine, without (meal A) or with (meal B) 3 g extra arginine. The postprandial utilization of meal arginine for NO production was determined from urinary (15)NO(3). We monitored endothelial function of the brachial artery, the stiffness of the common carotid artery, aortic pulse wave velocity and soluble markers related to endothelial function for 8 h. Meal A did not significantly increase plasma homocysteine and did not alter endothelial function markers. The amount of NO synthesized from meal arginine doubled after meal B (107.1 +/- 16.5% increase vs. meal A, P < 0.01) but was very low (271 +/- 84 ppm vs. 332 +/- 73 ppm, P < 0.05, respectively). After meal B, flow-mediated and nitroglycerine-induced dilation decreased but common carotid artery compliance, pulse wave velocity, plasma soluble intercellular adhesion molecule-1, and von Willebrand factor, and urinary cGMP did not differ when compared with meal A. Together, the data indicate that, in healthy men, meal amino acids do not adversely affect endothelial function, and meal arginine only slightly enters the NO pathway. Unexpectedly, arginine in physiological amounts may acutely lessen smooth muscle cell reactivity to a high dynamic NO release.

Noninvasive assessment of arterial stiffness and risk of atherosclerotic events in children.

Noninvasive assessment of vascular dysfunction in the pediatric population has taken advantage of the development of high-resolution ultrasound techniques. The most frequently used methods are the quantification of flow-mediated endothelium-dependent dilation of the brachial artery and measurement of the intima-media thickening of the carotid artery. Both reduced flow-mediated dilation and increased intima-media thickness have been proven to correlate with late cardiovascular events and/or mortality in adults. As these noninvasive methods can easily be applied in children, there have been recent investigations in high-risk pediatric patients harboring classical cardiovascular risk factors. Endothelial dysfunction and increased thickness of the intima media are currently observed in children with familial hypercholesterolemia, obesity, and type 1 diabetes mellitus. The association of early vascular dysfunction with a known risk factor is an important issue as these anomalies precede the formation of atherosclerotic plaques. Therefore, they may help in stratification of the risk for cardiovascular event and to better tailor therapeutic interventions in at risk children. Finally, these methods have been applied in specific pediatric populations, such as children with end-stage renal disease, chronic parenteral nutrition, HIV infection, and coarctation of the aorta. In these conditions, endothelial dysfunction and vascular remodeling are also present early in life and these data raise new possibilities in the understanding of the pathogenesis of atherosclerosis in these populations.