Abnormal vascular thickness and stiffness in young adults with type 1 diabetes: new insights from cutting-edge ultrasound modalities.

BACKGROUND: Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in patients with Type 1 Diabetes (T1D). Early markers of CVD include increased carotid intima-media thickness (CIMT) and pulse wave velocity (PWV), but these existing ultrasound technologies show limited spatial and temporal resolution in young adults. The purpose of this study is to evaluate the utility of high-resolution ultrasound modalities, including high frequency ultrasound CIMT (hfCIMT) and ultrafast ultrasound PWV (ufPWV), in young adults with Type 1 Diabetes. METHODS: This is a prospective single-center observational cohort study including 39 participants with T1D and 25 age and sex matched controls. All participants underwent hfCIMT and ufPWV measurements. hfCIMT and ufPWV measures of T1D were compared with controls and associations with age, sex, BMI, A1c, blood pressure, and lipids were studied. RESULTS: Mean age was 24.1 years old in both groups. T1D had a greater body mass index (27.7 [5.7] vs 23.1 [3.2] kg/m2), LDL Cholesterol, and estimated GFR, and had a mean A1c of 7.4 [1.0] % (57 mmol/mol) and diabetes duration of 16.1 [3.7] years with 56% using insulin pumps. In T1D, hfCIMT was significantly increased as compared to controls (0.435 ± 0.06 mm vs 0.379 ± 0.06 mm respectively, p < 0.01). ufPWV measures were significantly increased in T1D (systolic foot PWV: 5.29 ± 0.23 m/s vs 5.50 ± 0.37 m/s, p < 0.01; dicrotic notch PWV = 7.54 ± 0.46 m/s vs 7.92 ± 0.41 m/s, p < 0.01). Further, there was an impact of A1c-measured glycemia on hfCIMT, but this relationship was not seen with ufPWV. No significant statistical correlations between hfCIMT and ufPWV measures in either T1D or healthy controls were observed. CONCLUSION: Young adults with T1D present with differences in arterial thickness and stiffness when compared with controls. Use of novel high-resolution ultrasound measures describe important relationships between early structural and vascular pathophysiologic changes and are promising tools to evaluate pre-clinical CVD risk in youth with T1D. TRIAL REGISTRATION: ISRCTN91419926.

Impact of cardiopulmonary bypass on cerebrovascular autoregulation assessed by ultrafast ultrasound imaging.

Newborns with congenital heart disease undergoing cardiac surgery are at risk of neurodevelopmental impairment with limited understanding of the impact of intra-operative cardiopulmonary bypass (CPB), deep hypothermia and selective cerebral perfusion on the brain. We hypothesized that a novel ultrasound technique, ultrafast power Doppler (UPD), can assess variations of cerebral blood volume (CBV) in neonates undergoing cardiac surgery requiring CPB. UPD was performed before, during and after surgery in newborns with hypoplastic left heart syndrome undergoing a Norwood operation. We found that global CBV was not significantly different between patients and controls (P = 0.98) and between pre- and post-surgery (P = 0.62). UPD was able to monitor changes in CBV throughout surgery, revealing regional differences in CBV during hypothermia during which CBV correlated with CPB flow rate (R2  = 0.52, P = 0.021). Brain injury on post-operative magnetic resonance imaging was observed in patients with higher maximum variation in CBV. Our findings suggest that UPD can quantify global and regional brain perfusion variation during neonatal cardiac surgery with this first intra-operative application demonstrating an association between CBV and CPB flow rate, suggesting loss of autoregulation. Therefore, the measurement of CBV by UPD could enable optimization of cerebral perfusion during cardiac surgery in neonates. KEY POINTS: The impact of cardiopulmonary bypass (CPB) on the neonatal brain undergoing cardiac surgery is poorly understood. Ultrafast power Doppler (UPD) quantifies cerebral blood volume (CBV), a surrogate of brain perfusion. CBV varies throughout CPB surgery and is associated with variation of the bypass pump flow rate during deep hypothermia. Association between CBV and bypass pump flow rate suggests loss of cerebrovascular autoregulatory processes. Quantitative monitoring of cerebral perfusion by UPD could provide a direct parameter to optimize CPB flow rate.

Antenatal occlusion of a ductal arteriosus aneurysm: a potential postnatal surgical emergency. Case report and literature review.

Symptomatic presentation of ductal arteriosus aneurysm is usually a consequence of associated complications, including thromboembolism, infection, and compression of adjacent structures. In this case report, we present a thrombosed ductal aneurysm that developed antenatally with further postnatal progression of the thrombus and complete occlusion of the left pulmonary artery. Urgent surgical thrombectomy was successful and the post-operative course was uneventful.

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.

Radiation exposure in transcatheter patent ductus arteriosus closure: time to tune?

OBJECTIVES: The aims of this study were to describe radiation level at our institution during transcatheter patent ductus arteriosus occlusion and to evaluate the components contributing to radiation exposure. BACKGROUND: Transcatheter occlusion relying on X-ray imaging has become the treatment of choice for patients with patent ductus arteriosus. Interventionists now work hard to minimise radiation exposure in order to reduce risk of induced cancers. METHODS: We retrospectively reviewed all consecutive children who underwent transcatheter closure of patent ductus arteriosus from January 2012 to January 2016. Clinical data, anatomical characteristics, and catheterisation procedure parameters were reported. Radiation doses were analysed for the following variables: total air kerma, mGy; dose area product, Gy.cm2; dose area product per body weight, Gy.cm2/kg; and total fluoroscopic time. RESULTS: A total of 324 patients were included (median age=1.51 [Q1-Q3: 0.62-4.23] years; weight=10.3 [6.7-17.0] kg). In all, 322/324 (99.4%) procedures were successful. The median radiation doses were as follows: total air kerma: 26 (14.5-49.3) mGy; dose area product: 1.01 (0.56-2.24) Gy.cm2; dose area product/kg: 0.106 (0.061-0.185) Gy.cm2/kg; and fluoroscopic time: 2.8 (2-4) min. In multivariate analysis, a weight >10 kg, a ductus arteriosus width <2 mm, complications during the procedure, and a high frame rate (15 frames/second) were risk factors for an increased exposure. CONCLUSION: Lower doses of radiation can be achieved with subsequent recommendations: technical improvement, frame rate reduction, avoidance of biplane cineangiograms, use of stored fluoroscopy as much as possible, and limitation of fluoroscopic time. A greater use of echocardiography might even lessen the exposure.

Adverse remodelling in tetralogy of Fallot: From risk factors to imaging analysis and future perspectives.

Although contemporary outcomes of initial surgical repair of tetralogy of Fallot (TOF) are excellent, the survival of adult patients remains significantly lower than that of the normal population due to the high incidence of heart failure, ventricular arrhythmias, and sudden cardiac death. The underlying mechanisms are only partially understood but involve an adverse biventricular response, so-called remodelling, to key stressors such as right ventricular (RV) pressure-and/or volume-overload, myocardial fibrosis, and electro-mechanical dyssynchrony. In this review, we explore risk factors and mechanisms of biventricular remodelling, from histological to electro-mechanical aspects, and the role of imaging in their assessment. We discuss unsolved challenges and future directions to better understand and treat the long-term sequelae of this complex congenital heart disease.

The brain of fetuses with congenital diaphragmatic hernia shows signs of hypoxic injury with loss of progenitor cells, neurons, and oligodendrocytes.

Congenital diaphragmatic hernia (CDH) is a birth defect characterized by incomplete closure of the diaphragm, herniation of abdominal organs into the chest, and compression of the lungs and the heart. Besides complications related to pulmonary hypoplasia, 1 in 4 survivors develop neurodevelopmental impairment, whose etiology remains unclear. Using a fetal rat model of CDH, we demonstrated that the compression exerted by herniated organs on the mediastinal structures results in decreased brain perfusion on ultrafast ultrasound, cerebral hypoxia with compensatory angiogenesis, mature neuron and oligodendrocyte loss, and activated microglia. In CDH fetuses, apoptosis was prominent in the subventricular and subgranular zones, areas that are key for neurogenesis. We validated these findings in the autopsy samples of four human fetuses with CDH compared to age- and sex-matched controls. This study reveals the molecular mechanisms and cellular changes that occur in the brain of fetuses with CDH and creates opportunities for therapeutic targets.

Modeling the Relationship Between Diastolic Phenotype and Outcomes in Pediatric Hypertrophic Cardiomyopathy.

BACKGROUND: Pediatric hypertrophic cardiomyopathy (HCM) is associated with adverse events. The contribution of diastolic dysfunction to adverse events is poorly understood. The aim of this study was to explore the association between diastolic phenotype and outcomes in pediatric patients with HCM. METHODS: Children <18 years of age with diagnosed with HCM were included. Diastolic function parameters were measured from the first echocardiogram at the time of diagnosis, including Doppler flow velocities, tissue Doppler velocities, and left atrial volume and function. Using principal-component analysis, key features in echocardiographic parameters were identified. The principal components were regressed to freedom from major adverse cardiac events (MACE), defined as implantable cardioverter-defibrillator insertion, myectomy, aborted sudden cardiac death, transplantation, need for mechanical circulatory support, and death. RESULTS: Variables that estimate left ventricular filling pressures were highly collinear and associated with MACE (hazard ratio, 0.86; 95% CI, 0.75-1.00), though this was no longer significant after controlling for left ventricular thickness and genetic variation. Left atrial size parameters adjusted for body surface area were independently associated with outcomes in the covariate-adjusted model (hazard ratio, 0.69; 95% CI, 0.5-0.94). The covariate-adjusted model had an Akaike information criterion of 213, an adjusted R2 value of 0.78, and a concordance index of 0.82 for association with MACE. CONCLUSION: Echocardiographic parameters of diastolic dysfunction were associated with MACE in this population study, in combination with the severity of left ventricular hypertrophy and genetic variation. Left atrial size parameters adjusted for body surface area were independently associated with adverse events. Additional study of diastolic function parameters adjusted for patient size could facilitate the prediction of adverse events in pediatric patients with HCM.

Long-Term Enlargement of the Neo-Aortic Root and Aortic Arch Following Arch Reconstruction in Hypoplastic Left Heart Syndrome.

BACKGROUND: Long-term enlargement of the aortic arch after aortic arch reconstruction (AAR) in hypoplastic left heart syndrome (HLHS) is not well described. METHODS: Aortic arch measurements for 50 patients with HLHS who achieved Fontan completion were converted to Pediatric Heart Network z-scores. Dimensions were assessed using linear mixed models and differences among time points were evaluated with F-tests. Sub-analysis was conducted comparing Norwood (n=36) vs hybrid (n=14) strategies. RESULTS: Median time to last imaging was 6.4 (IQR, 3.5-11.3) years. Prior to intervention, the main pulmonary artery was dilated whereas the ascending aorta (AA), transverse arch (TA), and isthmus (ISTH) were hypoplastic. With AAR, there were expected increases in all arch z-scores. The aortic arch continued to dilate after AAR reaching peak values at 7 months [Neo-Aortic Complex (NAC): z= 6.9 (5.6-8.0)] or 12 months following stage I [AAo: z=6.1 (2.9-8.3); TA: z=4.7 (3.0-5.9)]. Following peak values, there was a gradual decline in z-scores with most components still at least mildly dilated at 16 years [NAC: z=3.2 (3.1-3.9), AAo: z=3.9 (3.3-4.2); TA: z=3.1 (2.5-3.7)] with abrupt calibre change at ISTH: z= -0.8 (-1.1- -0.3)]. Norwood and hybrid strategies showed similar enlargement profiles after 7 months of age. CONCLUSIONS: Neo-aortic root and aortic arch in HLHS are enlarged early after AAR and continue to enlarge out of proportion to normal controls until 12 months of age, with gradual decline in enlargement up to adolescence. Further work should focus on modifiable surgical factors which may prove important to optimize arch growth and geometry.

Impact of Right Ventricular Pressure Overload on Myocardial Stiffness Assessed by Natural Wave Imaging.

BACKGROUND: Right ventricular (RV) hemodynamic performance determines the prognosis of patients with RV pressure overload. Using ultrafast ultrasound, natural wave velocity (NWV) induced by cardiac valve closure was proposed as a new surrogate to quantify myocardial stiffness. OBJECTIVES: This study aimed to assess RV NWV in rodent models and children with RV pressure overload vs control subjects and to correlate NWV with RV hemodynamic parameters. METHODS: Six-week-old rats were randomized to pulmonary artery banding (n = 6), Sugen hypoxia-induced pulmonary arterial hypertension (n = 7), or sham (n = 6) groups. They underwent natural wave imaging, echocardiography, and hemodynamic assessment at baseline and 6 weeks postoperatively. The authors analyzed NWV after tricuspid and after pulmonary valve closure (TVC and PVC, respectively). Conductance catheters were used to generate pressure-volume loops. In parallel, the authors prospectively recruited 14 children (7 RV pressure overload; 7 age-matched control subjects) and compared RV NWV with echocardiographic and invasive hemodynamic parameters. RESULTS: NWV significantly increased in RV pressure overload rat models (4.99 ± 0.27 m/s after TVC and 5.03 ± 0.32 m/s after PVC in pulmonary artery banding at 6 weeks; 4.89 ± 0.26 m/s after TVC and 4.84 ± 0.30 m/s after PVC in Sugen hypoxia at 6 weeks) compared with control subjects (2.83 ± 0.15 m/s after TVC and 2.72 ± 0.34 m/s after PVC). NWV after TVC correlated with both systolic and diastolic parameters including RV dP/dtmax (r = 0.75; P < 0.005) and RV Ees (r = 0.81; P < 0.005). NWV after PVC correlated with both diastolic and systolic parameters and notably with RV end-diastolic pressure (r = 0.65; P < 0.01). In children, NWV after both right valves closure in RV pressure overload were higher than in healthy volunteers (P < 0.01). NWV after PVC correlated with RV E/E' (r = 0.81; P = 0.008) and with RV chamber stiffness (r = 0.97; P = 0.03). CONCLUSIONS: Both RV early-systolic and early-diastolic myocardial stiffness show significant increase in response to pressure overload. Based on physiology and our observations, early-systolic myocardial stiffness may reflect contractility, whereas early-diastolic myocardial stiffness might be indicative of diastolic function.

Fast Thresholding of SVD Clutter Filter Using the Spatial Similarity Matrix and a Sum-Table Algorithm.

Singular value decomposition (SVD) has become a standard for clutter filtering of ultrafast ultrasound datasets. Its implementation requires the choice of appropriate thresholds to discriminate the singular value subspaces associated with tissue, blood, and noise signals. Comparing the similarity of the spatial singular vectors was shown to be a robust and efficient method to estimate the SVD thresholds. The correlation of the spatial singular vector envelopes gives the spatial similarity matrix (SSM), which usually exhibits two square-like domains juxtaposed along the diagonal of the SSM, representing the tissue and the blood subspaces. Up to now, the proposed methods to automatically segment these two subspaces on the SSM were of high computational complexity and had a long processing time. Here, we propose an optimized algorithm using a sum-table approach that decreases the complexity by two orders of magnitude: O(n4) to O(n2) . The proposed method resulted in processing times lower than 0.08 s for datasets of 2000 frames, whereas previous algorithms took more than 26 h, so an improvement by a factor of 106. We illustrated this adaptive square-fitting on the SSM in the in vivo case of human neonate brain imaging and carotid imaging with various conditions of clutter. This optimization of SVD thresholding is essential to develop the use of adaptive clutter filtering, especially for real-time applications or block-wise processing.

Assessing engineered tissues and biomaterials using ultrasound imaging: In vitro and in vivo applications.

Quantitative assessment of the structural, functional, and mechanical properties of engineered tissues and biomaterials is fundamental to their development for regenerative medicine applications. Ultrasound (US) imaging is a non-invasive, non-destructive, and cost-effective technique capable of longitudinal and quantitative monitoring of tissue structure and function across centimeter to sub-micron length scales. Here we present the fundamentals of US to contextualize its application for the assessment of biomaterials and engineered tissues, both in vivo and in vitro. We review key studies that demonstrate the versatility and broad capabilities of US for clinical and pre-clinical biomaterials research. Finally, we highlight emerging techniques that further extend the applications of US, including for ultrafast imaging of biomaterials and engineered tissues in vivo and functional monitoring of stem cells, organoids, and organ-on-a-chip systems in vitro.

Outcomes Following Closure of Secundum Atrial Septal Defect in Children ≤ 15 kg in a French Tertiary Centre.

Secundum atrial septal defects (sASDs) are common congenital cardiac defects mostly treated using a transcatheter approach. However, small children (<15 kg) are still undergoing surgical sASD closure in many centres. Although both options have been proved to have excellent results in children, comparative data of the two techniques are missing for patients ≤ 15 kg. The medical records of children ≤ 15 kg who underwent sASD surgical (group A) and transcatheter (group B) closure between 2010 and 2023 were reviewed retrospectively. Twenty-five children in group A and twenty-two in group B were included (mean weight 8.9 kg in group A and 10.3 kg in group B). The main indications for closure were right heart enlargement and failure to thrive. Major complications occurred in two patients in group A and none in group B. Minor complications occurred in eight patients in group A and one in group B. At last follow-up, symptoms resolved completely or improved significantly for all infants, with the exception of failure to thrive in the sub-population of children with extra-cardiac comorbidities. sASD closure can be performed safely in symptomatic infants ≤ 15 kg, even in the presence of comorbidity, and should not be postponed. However, in patients with extra-cardiac comorbidities, the only indication of growth retardation must be carefully evaluated.

The fundamental mechanisms of the Korotkoff sounds generation.

Blood pressure measurement is the most widely performed clinical exam to predict mortality risk. The gold standard for its noninvasive assessment is the auscultatory method, which relies on listening to the so-called "Korotkoff sounds" in a stethoscope placed at the outlet of a pneumatic arm cuff. However, more than a century after their discovery, the origin of these sounds is still debated, which implies a number of clinical limitations. We imaged the Korotkoff sound generation in vivo at thousands of images per second using ultrafast ultrasound. We showed with both experience and theory that Korotkoff sounds are paradoxically not sound waves emerging from the brachial artery but rather shear vibrations conveyed in surrounding tissues by the nonlinear pulse wave propagation. When these shear vibrations reached the stethoscope, they were synchronous, correlated, and comparable in intensity with the Korotkoff sounds. Understanding this mechanism could ultimately improve blood pressure measurement and provide additional understanding of arterial mechanical properties.

Melody Mitral Valve Is a Promising Alternative to Mechanical Valve Replacement for Young Children.

PURPOSE: The purpose of this study was to compare outcomes of Melody mitral valve to mechanical mitral valve replacement (MVR) for young children. DESCRIPTION: Children who underwent Melody MVR from 2014 to 2020 were case-matched to mechanical MVR patients. Transplant-free survival and cumulative incidence of reintervention were compared. A subanalysis was performed for infants aged < 1 year (9 Melody MVRs and their matches). EVALUATION: Twelve children underwent Melody MVR. Two children (17%) salvaged from mechanical support died. Five of 10 survivors (50%) had subsequent MVR. At 1 and 3 years, transplant-free survival (Melody: 83%, 83%; mechanical: 83%, 67%; P = .180) and reintervention (Melody: 9%, 39%; mechanical: 0%, 18%; P = .18) were equivalent between groups. For children < 1 year of age, Melody MVR had a modest survival benefit (Melody: 89%, 89%; mechanical: 80%, 60%; P = .046), while rate of reintervention remained equivalent (Melody: 13%, 32%; mechanical: 0%, 22%; P = .32). CONCLUSIONS: For patients < 1 year old, Melody MVR offers a promising alternative and is a reasonable bridge to mechanical MVR, which can be performed safely at an older age. Further studies are necessary to corroborate these findings.

Local arterial stiffness measured by ultrafast ultrasound imaging in childhood cancer survivors treated with anthracyclines.

Background: There is conflicting literature regarding the long-term effect of anthracycline treatment on arterial stiffness. This study assessed local arterial stiffness using ultrafast ultrasound imaging (UUI) in anthracycline treated childhood cancer survivors, at rest and during exercise. Methods: 20 childhood cancer survivors (mean age 21.02 ± 9.45 years) treated with anthracyclines (mean cumulative dose 200.7 ± 126.80 mg/m2) and 21 healthy controls (mean age 26.00 ± 8.91 years) were included. Participants completed a demographic survey, fasting bloodwork for cardiovascular biomarkers, and performed a submaximal exercise test on a semi-supine bicycle. Pulse wave velocity (PWV) was measured in the left common carotid artery by direct pulse wave imaging using UUI at rest and submaximal exercise. Both PWV at the systolic foot (PWV-SF) and dicrotic notch (PWV-DN) were measured. Central (carotid-femoral) PWV was obtained by applanation tonometry. Carotid measurements were taken by conventional ultrasound. Measures were compared using two-tailed Students t-test or Chi-squared test, as appropriate. Results: There was no statistically significant difference (p > 0.05) between childhood cancer survivors and healthy controls in demographic parameters (age, sex, weight, height, BMI), blood biomarkers (total cholesterol, triglycerides, LDL-c, HDL-c, hs-CRP, fasting glucose, insulin, Hb A1c), cardiovascular parameters (intima media thickness, systolic and diastolic blood pressure, heart rate, carotid diameters, distensibility) or PWV measured by UUI at rest or at exercise. There was also no difference in the cardiovascular adaptation between rest and exercise in the two groups (p > 0.05). Multivariate analysis revealed age (p = 0.024) and LDL-c (p = 0.019) to be significant correlates of PWV-SF in childhood cancer survivors, in line with previously published data. Conclusion: We did not identify a significant impact of anthracycline treatment in young survivors of childhood cancer on local arterial stiffness in the left common carotid artery as measured by UUI.

Impact of Ventricular Geometric Characteristics on Myocardial Stiffness Assessment Using Shear-Wave Velocity in Healthy Children and Young Adults.

BACKGROUND: Diastolic myocardial stiffness (MS) can serve as a key diagnostic parameter for congenital or acquired heart diseases. Using shear modulus and shear-wave velocity (SWV), shear-wave elastography (SWE) is an emerging ultrasound-based technique that can allow noninvasive assessment of MS. However, MS extrinsic parameters such as left ventricular geometric characteristics could affect shear-wave propagation. The aims of this study were to determine a range of normal values of MS using SWE in age groups of healthy children and young adults and to explore the impact of left ventricular geometric characteristics on SWE. METHODS: Sixty healthy volunteers were recruited in the study and divided into 2 groups: neonates (0-1 months old, n = 15) and >1 month old (1 month to 45 years of age, n = 45). SWE was performed using the Verasonics Vantage systems with a phased-array ultrasound probe. The anteroseptal basal segment was assessed in two views. SWE was electrocardiographically triggered during the end-diastolic phase. Conventional echocardiography was performed to assess ventricular function and anatomy. Results are presented as stiffness values along with mean velocity measurements and SDs. Simple and multivariate linear regression analyses were performed. RESULTS: For neonates, mean MS was 1.87 ± 0.79 kPa (range, 0.59-2.91 kPa; mean SWV, 1.37 ± 0.57 m/sec), with high variability and no correlation with age (P = .239). For this age group, no statistically significant correlation was found between MS and any demographic or echocardiographic parameters (P > .05). For the >1 month old group, a mean MS value of 1.67 ± 0.53 kPa was observed (range, 0.6-3 kPa; mean SWV, 1.29 ± 0.49 m/sec) for healthy volunteers. When paired for age, no sex-related difference was observed (P = .55). In univariate linear regression analysis, age (r = 0.83, P < .01), diastolic interventricular septal thickness (r = 0.72, P < .01), and left ventricular end-diastolic diameter (r = 0.67, P < .01) were the parameters with the highest correlation coefficients with MS. In a multiple linear regression analysis incorporating these three parameters as cofounding factors, age was the only statistically significant parameters (r = 0.81, P = .02). CONCLUSION: Diastolic MS increases linearly in children and young adults. Diastolic MS correlates more robustly with age than with myocardial and left ventricular geometric characteristics. However, the geometry affects SWV, implying the need to determine well-established boundaries in future studies for the clinical application of SWE.

Longitudinal Assessment of Cerebral Blood Volume Variation in Human Neonates Using Ultrafast Power Doppler and Diverging Waves.

Longitudinal assessment of brain perfusion is a critical parameter for neurodevelopmental outcome of neonates undergoing cardiopulmonary bypass procedure. In this study, we aim to measure the variations of cerebral blood volume (CBV) in human neonates during cardiac surgery, using Ultrafast Power Doppler and freehand scanning. To be clinically relevant, this method must satisfy three criteria: being able to image a wide field of view in the brain, show significant longitudinal CBV variations, and present reproducible results. To address the first point, we performed for the first time transfontanellar Ultrafast Power Doppler using a hand-held phased-array transducer with diverging waves. This increased the field of view more than threefold compared to previous studies using linear transducers and plane waves. We were able to image vessels in the cortical areas as well as the deep grey matter and temporal lobes. Second, we measured the longitudinal variations of CBV on human neonates undergoing cardiopulmonary bypass. When compared to a pre-operative baseline acquisition, the CBV exhibited significant variation during bypass: on average, + 20±3 % in the mid-sagittal full sector ( [Formula: see text]), - 11±3 % in the cortical regions ( [Formula: see text]) and - 10±4 % in the basal ganglia ( [Formula: see text]). Third, a trained operator performing identical scans was able to reproduce CBV estimates with a variability of 4% to 7.5% depending on the regions considered. We also investigated whether vessel segmentation could further improve reproducibility, but found that it actually introduced greater variability in the results. Overall, this study demonstrates the clinical translation of ultrafast power Doppler with diverging-waves and freehand scanning.