Decoupling Transmission and Transduction for Improved Durability of Highly Stretchable, Soft Strain Sensing: Applications in Human Health Monitoring.

This work presents a modular approach to the development of strain sensors for large deformations. The proposed method separates the extension and signal transduction mechanisms using a soft, elastomeric transmission and a high-sensitivity microelectromechanical system (MEMS) transducer. By separating the transmission and transduction, they can be optimized independently for application-specific mechanical and electrical performance. This work investigates the potential of this approach for human health monitoring as an implantable cardiac strain sensor for measuring global longitudinal strain (GLS). The durability of the sensor was evaluated by conducting cyclic loading tests over one million cycles, and the results showed negligible drift. To account for hysteresis and frequency-dependent effects, a lumped-parameter model was developed to represent the viscoelastic behavior of the sensor. Multiple model orders were considered and compared using validation and test data sets that mimic physiologically relevant dynamics. Results support the choice of a second-order model, which reduces error by 73% compared to a linear calibration. In addition, we evaluated the suitability of this sensor for the proposed application by demonstrating its ability to operate on compliant, curved surfaces. The effects of friction and boundary conditions are also empirically assessed and discussed.

In Vitro Assessment of Right Ventricular Outflow Tract Anatomy and Valve Orientation Effects on Bioprosthetic Pulmonary Valve Hemodynamics.

PURPOSE: The congenital heart defect Tetralogy of Fallot (ToF) affects 1 in 2500 newborns annually in the US and typically requires surgical repair of the right ventricular outflow tract (RVOT) early in life, with variations in surgical technique leading to large disparities in RVOT anatomy among patients. Subsequently, often in adolescence or early adulthood, patients usually require surgical placement of a xenograft or allograft pulmonary valve prosthesis. Valve longevity is highly variable for reasons that remain poorly understood. METHODS: This work aims to assess the performance of bioprosthetic pulmonary valves in vitro using two 3D printed geometries: an idealized case based on healthy subjects aged 11 to 13 years and a diseased case with a 150% dilation in vessel diameter downstream of the valve. Each geometry was studied with two valve orientations: one with a valve leaflet opening posterior, which is the native pulmonary valve position, and one with a valve leaflet opening anterior. RESULTS: Full three-dimensional, three-component, phase-averaged velocity fields were obtained in the physiological models using 4D flow MRI. Flow features, particularly vortex formation and reversed flow regions, differed significantly between the RVOT geometries and valve orientations. Pronounced asymmetry in streamwise velocity was present in all cases, while the diseased geometry produced additional asymmetry in radial flows. Quantitative integral metrics demonstrated increased secondary flow strength and recirculation in the rotated orientation for the diseased geometry. CONCLUSIONS: The compound effects of geometry and orientation on bioprosthetic valve hemodynamics illustrated in this study could have a crucial impact on long-term valve performance.

Assessment of the Reconstructed Pulmonary Circulation With Lung Perfusion Scintigraphy After Unifocalization and Repair of Tetralogy of Fallot With Major Aortopulmonary Collaterals.

BACKGROUND: Pulmonary vascular supply in tetralogy of Fallot (TOF) with major aortopulmonary collaterals (MAPCAs) is highly variable. Our approach to surgical management of this condition emphasizes early repair including unifocalization and reconstruction of the pulmonary circulation, incorporating all lung segments and addressing stenoses both proximal to and within the lung, in addition to ventricular septal defect closure. At our institution, we have over 15 years of experience using lung perfusion scintigraphy (LPS) to assess the distribution of pulmonary blood flow after complete unifocalization and repair. METHODS: We reviewed clinical and quantitative LPS data in 310 patients who underwent complete unifocalization and repair of TOF/MAPCAs from 2003 to 2018 at our institution. Postrepair relative lung perfusion distributions were determined from LPS initially obtained at our institution within 60 days after repair and thereafter. RESULTS: Total lung perfusion to the right and left lungs was 58.0% ± 14.2% and 42.0% ± 14.2%, respectively. Perfusion was balanced in 75% of patients and unbalanced in 25%, including 11% in whom it was extremely unbalanced. On multivariable analysis, older age at repair, surgery other than a single-stage complete unifocalization, and native anatomy consisting of unilateral pulmonary blood supply through a ductus arteriosus were associated with unbalanced perfusion. CONCLUSION: We present our experience using LPS as an outcome measure after surgical repair of TOF/MAPCAs. Balanced lung perfusion was present in the majority of patients who had complete repair of TOF/MAPCAs performed at our center.

Assessment of airway abnormalities in patients with tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collaterals.

BACKGROUND: Children with tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collaterals (TOF/MAPCAs) are at risk for post-operative respiratory complications after undergoing unifocalisation surgery. Thus, we assessed and further defined the incidence of airway abnormalities in our series of over 500 children with TOF/MAPCAs as determined by direct laryngoscopy, chest computed tomography (CT), and/or bronchoscopy. METHODS: The medical records of all patients with TOF/MAPCAs who underwent unifocalisation or pulmonary artery reconstruction surgery from March, 2002 to June, 2018 were reviewed. Anaesthesia records, peri-operative bronchoscopy, and/or chest CT reports were reviewed to assess for diagnoses of abnormal or difficult airway. Associations between chromosomal anomalies and airway abnormalities - difficult anaesthetic airway, bronchoscopy, and/or CT findings - were defined. RESULTS: Of the 564 patients with TOF/MAPCAs who underwent unifocalisation or pulmonary artery reconstruction surgery at our institution, 211 (37%) had a documented chromosome 22q11 microdeletion and 28 (5%) had a difficult airway/intubation reported at the time of surgery. Chest CT and/or peri-operative bronchoscopy were performed in 234 (41%) of these patients. Abnormalities related to malacia or compression were common. In total 35 patients had both CT and bronchoscopy within 3 months of each other, with concordant findings in 32 (91%) and partially concordant findings in the other 3. CONCLUSION: This is the largest series of detailed airway findings (direct laryngoscopy, CT, and bronchoscopy) in TOF/MAPCAS patients. Although these findings are specific to an at-risk population for airway abnormalities, they support the utility of CT and /or bronchoscopy in detecting airway abnormalities in patients with TOF/MAPCAs.

Serial assessment of postoperative ventricular mechanics in young children with tetralogy of Fallot: Comparison of transannular patch and valve-sparing repair.

BACKGROUND: Little is known about the early time course of biventricular function and mechanics after tetralogy of Fallot (TOF) repair. We sought to evaluate and describe the evolution of the right ventricle (RV) after TOF repair in young infants and children using conventional echocardiographic parameters and global longitudinal strain (GLS). METHODS: A retrospective review was performed of all patients with TOF and pulmonary stenosis who underwent repair from January 2002 to September 2015 and had at least 3 serial postsurgical echocardiograms spanning from infancy to early childhood (<8 years). Student's t test was performed to compare patients who underwent valve sparing (VS) versus transannular patch (TAP) repair. ANOVA was used to track measures of ventricular systolic function over time. RESULTS: We analyzed 151 echocardiograms performed on 42 patients. Pulmonary regurgitation (PR, moderate or severe) and the RV to left ventricular (LV) basal dimension ratio were higher in TAP patients (P < .04 at all-time points). Along with a significant increase in RV basal diameter Z-score in the TAP group (P < .001), there was an improvement in RV and LV GLS over time in both groups (P < .001). The LV GLS at last follow-up was lower in patients who underwent reoperation than those who did not (P = .050). LV GLS at the last follow-up echocardiogram was lower in patients with significant PR than those without (P < .001). CONCLUSIONS: Ventricular function appeared improve over time from the initial postoperative period in TOF patients. TAP repair was associated with a progressively higher RV/LV ratio in young children. GLS and RV/LV basal diameter ratio may be useful when following young children after TOF repair. Further research is necessary to understand the trajectory of ventricular functional and volumetric changes in young children in order to provide the most effective lifetime management of patients with TOF.

Assessing Statewide All-Cause Future One-Year Mortality: Prospective Study With Implications for Quality of Life, Resource Utilization, and Medical Futility.

BACKGROUND: For many elderly patients, a disproportionate amount of health care resources and expenditures is spent during the last year of life, despite the discomfort and reduced quality of life associated with many aggressive medical approaches. However, few prognostic tools have focused on predicting all-cause 1-year mortality among elderly patients at a statewide level, an issue that has implications for improving quality of life while distributing scarce resources fairly. OBJECTIVE: Using data from a statewide elderly population (aged ≥65 years), we sought to prospectively validate an algorithm to identify patients at risk for dying in the next year for the purpose of minimizing decision uncertainty, improving quality of life, and reducing futile treatment. METHODS: Analysis was performed using electronic medical records from the Health Information Exchange in the state of Maine, which covered records of nearly 95% of the statewide population. The model was developed from 125,896 patients aged at least 65 years who were discharged from any care facility in the Health Information Exchange network from September 5, 2013, to September 4, 2015. Validation was conducted using 153,199 patients with same inclusion and exclusion criteria from September 5, 2014, to September 4, 2016. Patients were stratified into risk groups. The association between all-cause 1-year mortality and risk factors was screened by chi-squared test and manually reviewed by 2 clinicians. We calculated risk scores for individual patients using a gradient tree-based boost algorithm, which measured the probability of mortality within the next year based on the preceding 1-year clinical profile. RESULTS: The development sample included 125,896 patients (72,572 women, 57.64%; mean 74.2 [SD 7.7] years). The final validation cohort included 153,199 patients (88,177 women, 57.56%; mean 74.3 [SD 7.8] years). The c-statistic for discrimination was 0.96 (95% CI 0.93-0.98) in the development group and 0.91 (95% CI 0.90-0.94) in the validation cohort. The mortality was 0.99% in the low-risk group, 16.75% in the intermediate-risk group, and 72.12% in the high-risk group. A total of 99 independent risk factors (n=99) for mortality were identified (reported as odds ratios; 95% CI). Age was on the top of list (1.41; 1.06-1.48); congestive heart failure (20.90; 15.41-28.08) and different tumor sites were also recognized as driving risk factors, such as cancer of the ovaries (14.42; 2.24-53.04), colon (14.07; 10.08-19.08), and stomach (13.64; 3.26-86.57). Disparities were also found in patients' social determinants like respiratory hazard index (1.24; 0.92-1.40) and unemployment rate (1.18; 0.98-1.24). Among high-risk patients who expired in our dataset, cerebrovascular accident, amputation, and type 1 diabetes were the top 3 diseases in terms of average cost in the last year of life. CONCLUSIONS: Our study prospectively validated an accurate 1-year risk prediction model and stratification for the elderly population (≥65 years) at risk of mortality with statewide electronic medical record datasets. It should be a valuable adjunct for helping patients to make better quality-of-life choices and alerting care givers to target high-risk elderly for appropriate care and discussions, thus cutting back on futile treatment.

Longitudinal Assessment of the Doppler-Estimated Maximum Gradient in Patients With Congenital Valvar Aortic Stenosis Pre- and Post-Balloon Valvuloplasty.

BACKGROUND: Aortic stenosis has been reported to manifest a slow rate of progression in mild disease, with a greater likelihood of progression in patients with moderate-severe disease. The natural history of the Doppler-estimated maximum gradient (DEMG) in patients after balloon aortic valvuloplasty (BAVP) has not previously been studied on a large scale. METHODS AND RESULTS: A retrospective review was performed of 360 patients from 1984 to 2012 with aortic stenosis, providing a total of 2059 echocardiograms both before and after BAVP. Patients were excluded if they had an intervention within the first 30 days of life. The relationships between the aortic stenosis DEMG and several predictors (age at initial study, body surface area, valve morphology, and initial DEMG) were explored using linear mixed effect models. Patients with a unicommissural aortic valve had a significantly higher rate of progression compared with those with a bicommissural aortic valve (0.81 and 0.45 mm Hg/year; P<0.001). The median rate of progression in the post-BAVP group was significantly lower than the median pre-BAVP rate of progression (n=34; pre-BAVP 3.97 [1.69-8.7] mm Hg/year; post-BAVP 0.40 [-1.80 to 3.88] mm Hg/year; P<0.008). When adjusted for body surface area, there was no significant increase in the DEMG (-0.03 mm Hg/m2 per year; P<0.001). CONCLUSIONS: There is a statistically significant increase in the DEMG over time in patients with aortic stenosis. After balloon dilation, the DEMG rate of change is reduced compared with that pre-dilation. Given the effect of body surface area on DEMG progression, more frequent observation should be made during periods of rapid somatic growth.

Direct physiologic assessment of anomalous aortic origin of a coronary artery: Enhanced diagnostics or illusion of insight?

Fractional flow reserve and intravascular ultrasound evaluation are technically feasible in patients with congenitally abnormal coronary arteries arising from the wrong aortic sinus, including those with a slitlike orifice and presumed intramural course. Incorporation of fractional flow reserve and intravascular ultrasound into the evaluation of adults with anomalous coronary artery origins will provide additional data and may be useful in risk assessment, although these data should be interpreted with caution, as the validity of fractional flow reserve findings in this population has not been established. The applicability of fractional flow reserve thresholds for acute coronary syndromes to patients with anomalous coronary artery origins is unknown. Further study will be needed to determine how best to incorporate fractional flow reserve data in the evaluation and management of these patients.

Defining and characterizing the critical transition state prior to the type 2 diabetes disease.

BACKGROUND: Type 2 diabetes mellitus (T2DM), with increased risk of serious long-term complications, currently represents 8.3% of the adult population. We hypothesized that a critical transition state prior to the new onset T2DM can be revealed through the longitudinal electronic medical record (EMR) analysis. METHOD: We applied the transition-based network entropy methodology which previously identified a dynamic driver network (DDN) underlying the critical T2DM transition at the tissue molecular biological level. To profile pre-disease phenotypical changes that indicated a critical transition state, a cohort of 7,334 patients was assembled from the Maine State Health Information Exchange (HIE). These patients all had their first confirmative diagnosis of T2DM between January 1, 2013 and June 30, 2013. The cohort's EMRs from the 24 months preceding their date of first T2DM diagnosis were extracted. RESULTS: Analysis of these patients' pre-disease clinical history identified a dynamic driver network (DDN) and an associated critical transition state six months prior to their first confirmative T2DM state. CONCLUSIONS: This 6-month window before the disease state provides an early warning of the impending T2DM, warranting an opportunity to apply proactive interventions to prevent or delay the new onset of T2DM.

Assessment of Progressive Pathophysiology After Early Prenatal Diagnosis of the Ebstein Anomaly or Tricuspid Valve Dysplasia.

In fetuses with Ebstein anomaly or tricuspid valve dysplasia (EA/TVD), poor hemodynamic status is associated with worse neonatal outcome. It is not known whether EA/TVD fetuses with more favorable physiology earlier in gestation progress to more severe disease in the third trimester. We evaluated if echocardiographic indexes in EA/TVD fetuses presenting <24 weeks of gestation are reliable indicators of physiologic status later in pregnancy. This multicenter, retrospective study included 51 fetuses presenting at <24 weeks of gestation with EA/TVD and serial fetal echocardiograms ≥4 weeks apart. We designated the following as markers of poor outcome: absence of anterograde flow across the pulmonary valve, pulmonary valve regurgitation, cardiothoracic area ratio >0.48, left ventricular (LV) dysfunction, or tricuspid valve (TV) annulus Z-score >5.6. Median gestational age at diagnosis was 21 weeks (range, 18 to 24). Eighteen fetuses (35%) had no markers for poor hemodynamic status initially, whereas only 7 of these continued to have no markers of poor outcome in the third trimester. Nine of 27 fetuses (33%) with anterograde pulmonary blood flow on the first echocardiogram developed pulmonary atresia; 7 of 39 (18%) developed new pulmonary valve regurgitation. LV dysfunction was present in 2 (4%) patients at <24 weeks but in 14 (37%) later (p <0.001). The TV annulus Z-score and cardiothoracic area both increased from diagnosis to follow-up. In conclusion, progressive hemodynamic compromise was common in this cohort. Our study highlights that care must be taken in counseling before 24 weeks, as the absence of factors associated with poor outcome early in pregnancy may be falsely reassuring.

Haemodynamic impact of stent implantation for lateral tunnel Fontan stenosis: a patient-specific computational assessment.

BACKGROUND: The physiological importance of the lateral tunnel stenosis in the Fontan pathway for children with single ventricle physiology can be difficult to determine. The impact of the stenosis and stent implantation on total cavopulmonary connection resistance has not been characterized, and there are no clear guidelines for intervention. Methods and results A computational framework for haemodynamic assessment of stent implantation in patients with lateral tunnel stenosis was developed. Cardiac magnetic resonances images were reconstructed to obtain total cavopulmonary connection anatomies before stent implantation. Stents with 2-mm diameter increments were virtually implanted in each patient to understand the impact of stent diameter. Numerical simulations were performed in all geometries with patient-specific flow rates. Exercise conditions were simulated by doubling and tripling the lateral tunnel flow rate. The resulting total cavopulmonary connection vascular resistances were computed. A total of six patients (age: 14.4 ± 3.1 years) with lateral tunnel stenosis were included for preliminary analysis. The mean baseline resistance was 1.54 ± 1.08 WU · m(2) and dependent on the stenosis diameter. It was further exacerbated during exercise. It was observed that utilising a stent with a larger diameter lowered the resistance, but the resistance reduction diminished at larger diameters. CONCLUSIONS: Using a computational framework to assess the severity of lateral tunnel stenosis and the haemodynamic impact of stent implantation, it was observed that stenosis in the lateral tunnel pathway was associated with higher total cavopulmonary connection resistance than unobstructed pathways, which was exacerbated during exercise. Stent implantation could reduce the resistance, but the improvement was specific to the minimum diameter.

Exploring Value in Congenital Heart Disease: An Evaluation of Inpatient Admissions.

OBJECTIVES: Understanding value provides an important context for improvement. However, most health care models fail to measure value. Our objective was to categorize inpatient encounters within an academic congenital heart program based on clinical outcome and the cost to achieve the outcome (value). We aimed to describe clinical and nonclinical features associated with value. DESIGN: We defined hospital encounters based on outcome per resource utilized. We performed principal component and cluster analysis to classify encounters based on mortality, length of stay, hospital cost and revenue into six classes. We used nearest shrunken centroid to identify discriminant features associated with the cluster-derived classes. These features underwent hierarchical clustering and multivariate analysis to identify features associated with each class. STUDY SETTING/PATIENTS: We analyzed all patients admitted to an academic congenital heart program between September 1, 2009, and December 31, 2012. OUTCOME MEASURES/RESULTS: A total of 2658 encounters occurred during the study period. Six classes were categorized by value. Low-performing value classes were associated with greater institutional reward; however, encounters with higher-performing value were associated with a loss in profitability. Encounters that included insertion of a pediatric ventricular assist device (log OR 2.5 [95% CI, 1.78 to 3.43]) and acquisition of a hospital-acquired infection (log OR 1.42 [95% CI, 0.99 to 1.87]) were risk factors for inferior health care value. CONCLUSIONS: Among the patients in our study, institutional reward was not associated with value. We describe a framework to target quality improvement and resource management efforts that can benefit patients, institutions, and payers alike.

Preliminary Assessment of Tricuspid Valve Annular Velocity Parameters by Cardiac Magnetic Resonance Imaging in Adults with a Volume-Overloaded Right Ventricle: Comparison of Unrepaired Atrial Septal Defect and Repaired Tetralogy of Fallot.

The aim is to compare tricuspid valve (TV) atrioventricular junction (AVJ) annular motion parameters in unrepaired atrial septal defect (ASD) and repaired Tetralogy of Fallot (TOF) by cardiac magnetic resonance (CMR) imaging. We retrospectively reviewed CMR studies performed between November 2007 and November 2013 in patients 16-45 years of age with unrepaired ASD (with or without partial anomalous pulmonary venous return) and with repaired TOF, who had previous infundibulotomy, but have not undergone pulmonary valve replacement. Longitudinal motion of lateral TV in four-chamber view cine image was tracked through the cardiac cycle with custom software. Twenty TOF patients and 12 ASD patients were included, and values were compared with 80 controls. Right ventricular end-diastolic volume index and right ventricular end-systolic volume index were similar in the ASD and TOF groups and were significantly higher in both groups than in controls. Maximum displacement of the TV in systole, velocity at half-maximal displacement during systole, and velocity at half-maximal displacement during early diastole were all significantly lower in the TOF group than the ASD group [1.39 ± 0.47 vs. 2.21 ± 0.46 (cm, p < 0.01), 5.9 ± 2.1 vs. 10.1 ± 2.3 (cm/s, p < 0.01), and 7.7 ± 2.6 vs. 10.9 ± 3.1 (cm/s, p < 0.05)]. TOF patients have diminished early diastolic TV AVJ velocity compared to patients with an unrepaired ASD, despite similar RV volumes. This observation could suggest diastolic dysfunction or cardiac mechanics unique to the postoperative, volume-overloaded right ventricle in patients with repaired TOF.

Angioplasty of obstructed homograft conduits in the right ventricular outflow tract with ultra-noncompliant balloons: assessment of therapeutic efficacy and conduit tears.

BACKGROUND: Angioplasty and stent placement in right ventricle-to-pulmonary artery (RV-PA) conduits have been shown to prolong the functional lifespan of a conduit. Safety and efficacy of angioplasty of obstructed RV-PA homografts using ultra-noncompliant (UNC) or ultrahigh-pressure balloons are unknown. METHODS AND RESULTS: From 2004 to 2012, 70 patients underwent 76 procedures for angioplasty of RV-PA homografts with UNC Atlas balloons. The UNC group was compared with a partially contemporaneous control cohort of 81 patients who underwent 84 angioplasty procedures with conventional balloons. Acute hemodynamic changes after angioplasty of homografts with UNC balloons included significantly reduced RV:Ao pressure ratio (P=0.02) and right ventricular outflow tract gradients (P≤0.001). Balloon waist resolution was more frequently achieved with UNC balloons (P=0.04), and balloon rupture occurred less often (P<0.001). Conduit tears of any severity occurred in 22% of patients overall and were more common in the UNC group (P=0.001). Patients with any conduit tear had significantly greater reduction in their RV:Ao pressure ratio (P<0.001) and right ventricular outflow tract gradient (P=0.004) than those with no tear. There were 4 unconfined tears, all in the UNC group, with no acute decompensations or deaths and only 1 patient who required surgical management. CONCLUSIONS: RV-PA conduit tears are common in patients undergoing angioplasty, but clinically important tears, which only occurred during UNC angioplasty in this series, were uncommon. UNC balloons can be used to good effect with significant reduction in right ventricular outflow tract gradient and the RV:Ao ratio when compared with conventional balloons.

Exercise stress echocardiographic assessment of outflow tract and ventricular function in patients with an obstructed right ventricular-to-pulmonary artery conduit after repair of conotruncal heart defects.

This study assessed right ventricular (RV) and RV outflow tract (RVOT) function and pressure in response to exercise in patients with an obstructed RV-pulmonary artery (PA) conduit using exercise stress echocardiography (ESE) to evaluate these parameters. RV-PA conduits inevitably develop stenosis and/or regurgitation over time. Assessment of conduit obstruction only at rest may not reveal the extent of physiologic perturbation related to RV pressure loading. Patients with a stenotic RV-PA conduit who were being considered for transcatheter pulmonary valve placement were approached prospectively. ESE was performed and ventricular images were obtained at rest and at peak exercise. Forty patients (median age 17 years) were enrolled. Most patients had tetralogy of Fallot (63%) and were in New York Heart Association class II (59%). Exercise stress echocardiographic images were adequate in 38 patients (95%). With exercise there was a significant increase in maximum instantaneous RVOT gradient from rest (59 vs 96 mm Hg, p <0.001); exercise-induced change in RVOT gradient correlated with global RV strain at rest (r = -0.3, p = 0.05). Compared to measurements at rest there were significant increases in median peak longitudinal strain of the left ventricular free wall, interventricular septum, and global left ventricular strain at peak exercise. There were no significant changes in median RV strain at peak exercise (RV free wall -14.3 [-26, -8] at rest vs -15.2 [-27, -3] at peak exercise, p = 0.87; global RV strain -13.9 [-32, -9] vs -15.1 [-23, -6], p = 0.11). In conclusion, using ESE it was possible to evaluate abnormal ventricular function and conduit dysfunction at peak exercise in patients with an obstructed RV-PA conduit.

Characterization of radiation exposure and effect of a radiation monitoring policy in a large volume pediatric cardiac catheterization lab.

OBJECTIVES: This study aimed to characterize radiation dose during cardiac catheterization in congenital heart disease and to assess changes in dose after the introduction of a radiation monitoring policy. BACKGROUND: Minimizing radiation exposure is an important patient safety initiative and relatively few data are available characterizing radiation dose for the broad spectrum of congenital cardiac catheter-based interventions. METHODS: Radiation dose data were reviewed on all cases since 7/1/05 at a single large center. Procedures were classified according to 20 common case types then subdivided into five age categories. Groups with <20 cases were excluded. Radiation dose was estimated by cumulative air KERMA (mGy) and DAP (dose area product, µGym(2)) which were reported as median and interquartile range (IQR). We also examined differences in radiation dose before and after the implementation of a radiation policy. RESULTS: Between 7/1/05 and 12/10/08, 3,365 cases were identified for inclusion. Radiation dose increased with age and procedural complexity. Patients were characterized into low, medium, and high dose categories relative to each other. "Low" dose cases included isolated pulmonary or aortic valvotomy, pre-Fontan assessment, and ASD closure. "High" dose cases involved multiple procedures in pulmonary arteries or veins. After introduction of a radiation policy, there was a significant decrease in radiation dose across a variety of case types, particularly among infants and young children. CONCLUSIONS: Radiation dose in congenital cardiac catheterization varies by age and procedure type. A radiation monitoring and notification policy may have contributed to reduced radiation dose.

Assessment of left ventricular endocardial fibroelastosis in fetuses with aortic stenosis and evolving hypoplastic left heart syndrome.

Systematic evaluation of left ventricular (LV) endocardial fibroelastosis (EFE) in the fetus has not been reported. The role of EFE in the pre- and postnatal evolution of hypoplastic left heart disease, and the implications of EFE for outcomes after prenatal intervention for fetal aortic stenosis with evolving hypoplastic left heart syndrome have also not been determined. A 4-point grading system (0-3) was devised for the assessment of fetal LV echogenicity, which was presumed to be due to EFE. Two reviewers independently graded EFE on the preintervention echocardiograms of fetuses treated with in utero aortic valvuloplasty for evolving hypoplastic left heart syndrome from 2000 to 2008. Intra- and interobserver reproducibility was determined for the EFE grade and characterization of related echocardiographic features. The relations among EFE severity, other left heart anatomic and physiologic variables, and postintervention outcomes were analyzed. The assessment and grading of EFE was possible for both observers in all 74 fetuses studied. By consensus, the EFE severity was grade 1 in 31 patients, grade 2 in 32, and grade 3 in 11. Fetuses with mild (grade 1) EFE had significantly greater maximum instantaneous aortic stenosis gradients (e.g., higher LV pressures) and less globular LV geometry than patients with grade 2 or 3 EFE on preintervention echocardiogram. The severity of EFE was not associated with the size of the aortic valve or LV. From preintervention to late gestation, the time-indexed change in LV end-diastolic volume was significantly greater in fetuses with grade 1 EFE than those with more severe EFE. Incorporation of EFE severity into our previously published threshold score improved the sensitivity and positive predictive value for the postnatal biventricular outcomes. In conclusion, echocardiographic grading of EFE is possible, with reasonable intra- and interobserver reliability in midgestation fetuses with evolving hypoplastic left heart syndrome. EFE severity corresponded to some indexes of left heart size, geometry, and function and with the probability of a biventricular outcome postnatally. Additional experience and external validation of the EFE grading scoring system are necessary.