Update on Prenatal Detection Rate of Critical Congenital Heart Disease Before and During the COVID-19 Pandemic.

Prenatal diagnosis of critical congenital heart disease (CCHD) has improved over time, and previous studies have identified CCHD subtype and socioeconomic status as factors influencing rates of prenatal diagnosis. Our objective of this single-center study was to compare prenatal diagnosis rates of newborns with CCHD admitted for cardiac intervention from the COVID-19 pandemic period (March 2020 to March 2021) to the pre-pandemic period and identify factors associated with the lack of CCHD prenatal diagnosis. The overall rate of CCHD and rates of the various CCHD diagnoses were calculated and compared with historical data collection periods (2009-2012 and 2013-2016). Compared with the 2009-2012 pre-pandemic period, patients had 2.17 times higher odds of having a prenatal diagnosis of CCHD during the pandemic period controlling for lesion type (aOR = 2.17, 95% CI 1.36-3.48, p = 0.001). Single ventricle lesions (aOR 6.74 [4.64-9.80], p < 0.001) and outflow tract anomalies (aOR 2.20 [1.56-3.12], p < 0.001) had the highest odds of prenatal diagnosis compared with the remaining lesions. Patients with outflow tract anomalies had higher odds for prenatal detection in the pandemic period compared with during the 2009-2012 pre-pandemic period (aOR 2.01 [1.06-3.78], p = 0.031). In conclusion, prenatal detection of CCHD among newborns presenting for cardiac intervention appeared to have improved during the pandemic period.

A Randomized Trial of an Exclusive Human Milk Diet in Neonates with Single Ventricle Physiology.

OBJECTIVE: To determine whether weight gain velocity (g/kg/day) 30 days after the initiation of feeds after cardiac surgery and other clinical outcomes improve in infants with single ventricle physiology fed an exclusive human milk diet compared with a mixed human and bovine diet. STUDY DESIGN: In this multicenter, randomized, single blinded, controlled trial, term neonates 7 days of age or younger with single ventricle physiology and anticipated cardiac surgical palliation within 30 days of birth were enrolled at 10 US centers. Both groups received human milk if fed preoperatively. During the 30 days after feeds were started postoperatively, infants in the intervention group received human milk fortified once enteral intake reached 60 mL/kg/day with a human milk-based fortifier designed for term neonates. The control group received standard fortification with formula once enteral intake reached 100 mL/kg/day. Perioperative feeding and parenteral nutrition study algorithms were followed. RESULTS: We enrolled 107 neonates (exclusive human milk = 55, control = 52). Baseline demographics and characteristics were similar between the groups. The median weight gain velocity at study completion was higher in exclusive human milk vs control group (12 g/day [IQR, 5-18 g/day] vs 8 g/day [IQR, 0.4-14 g/day], respectively; P = .03). Other growth measures were similar between groups. Necrotizing enterocolitis of all Bell stages was higher in the control group (15.4 % vs 3.6%, respectively; P = .04). The incidence of other major morbidities, surgical complications, length of hospital stay, and hospital mortality were similar between the groups. CONCLUSIONS: Neonates with single ventricle physiology have improved short-term growth and decreased risk of NEC when receiving an exclusive human milk diet after stage 1 surgical palliation. TRIAL REGISTRATION: This trial is registered with ClinicalTrials.gov (www. CLINICALTRIALS: gov, Trial ID: NCT02860702).

Third Trimester Fetal Heart Rates in Antibody-Mediated Complete Heart Block Predict Need for Neonatal Pacemaker Placement.

Congenital complete heart block (CCHB) affects 1 in 20,000 newborns. This study evaluates fetal and neonatal risk factors predictive of neonatal pacemaker placement in antibody-mediated complete heart block. The Children's Hospital Los Angeles institutional fetal, pacemaker, and medical record databases were queried for confirmed SSA/SSB cases of CCHB between January 2004 and July 2019. Cases excluded were those with a diagnosis beyond the neonatal period, diagnosis of a channelopathy, or if maternal antibody status was unknown. We recorded the gestational age (GA), birth weight (BW), fetal heart rates (FHRs) of the last echocardiogram before delivery, specific neonatal ECG and echocardiogram findings, age at pacemaker placement, and mortality. Of 43 neonates identified with CCHB, 27 had confirmed maternal antibody exposure. Variables associated with neonatal pacemaker implantation were FHRs < 50 bpm (p = 0.005), neonatal heart rates < 52 bpm (p = 0.015), and neonatal left ventricular fractional shortening (FS) percentages < 34% (p = 0.03). On multivariate analysis, FHR remained significant (p = 0.03) and demonstrated an increased risk of neonatal pacemaker placement by an odds ratio of 12.5 (95% CI 1.3-116, p = 0.05). The median GA at which the FHR was obtained was 34 weeks (IQR 26-35 weeks). Neonatal pacemaker placement was highly associated with a FHR < 50 bpm, neonatal HR < 52 bpm, and neonatal FS < 34%. FHRs at 34 weeks GA (IQR 26-35 weeks) correlated well with postnatal heart rates and were predictive of neonatal pacemaker placement.

Contemporary Outcomes in Tetralogy of Fallot With Absent Pulmonary Valve After Fetal Diagnosis.

Background Tetralogy of Fallot with absent pulmonary valve is associated with high mortality, but it remains difficult to predict outcomes prenatally. We aimed to identify risk factors for mortality in a large multicenter cohort. Methods and Results Fetal echocardiograms and clinical data from 19 centers over a 10-year period were collected. Primary outcome measures included fetal demise and overall mortality. Of 100 fetuses, pregnancy termination/postnatal nonintervention was elected in 22. Of 78 with intention to treat, 7 (9%) died in utero and 21 (27%) died postnatally. With median follow-up of 32.9 months, no deaths occurred after 13 months. Of 80 fetuses with genetic testing, 46% had chromosomal abnormalities, with 22q11.2 deletion in 35%. On last fetal echocardiogram, at a median of 34.6 weeks, left ventricular dysfunction independently predicted fetal demise (odds ratio [OR], 7.4; 95% CI 1.3, 43.0; P=0.026). Right ventricular dysfunction independently predicted overall mortality in multivariate analysis (OR, 7.9; 95% CI 2.1-30.0; P=0.002). Earlier gestational age at delivery, mediastinal shift, left ventricular/right ventricular dilation, left ventricular dysfunction, tricuspid regurgitation, and Doppler abnormalities were associated with fetal and postnatal mortality, although few tended to progress throughout gestation on serial evaluation. Pulmonary artery diameters did not correlate with outcomes. Conclusions Perinatal mortality in tetralogy of Fallot with absent pulmonary valve remains high, with overall survival of 64% in fetuses with intention to treat. Right ventricular dysfunction independently predicts overall mortality. Left ventricular dysfunction predicts fetal mortality and may influence prenatal management and delivery planning. Mediastinal shift may reflect secondary effects of airway obstruction and abnormal lung development and is associated with increased mortality.

Current knowledge of Chagas-related heart disease among pediatric cardiologists in the United States.

BACKGROUND: Chagas disease is a pathogenic parasitic infection with approximately 8 million cases worldwide and greater than 300,000 cases in the United States (U.S.). Chagas disease can lead to chronic cardiomyopathy and cardiac complications, with variable cardiac presentations in pediatrics making it difficult to recognize. The purpose of our study is to better understand current knowledge and experience with Chagas related heart disease among pediatric cardiologists in the U.S. METHODS: We prospectively disseminated a 19-question survey to pediatric cardiologists via 3 pediatric cardiology listservs. The survey included questions about demographics, Chagas disease presentation and experience. RESULTS: Of 139 responses, 119 cardiologists treat pediatric patients in the U.S. and were included. Most providers (87%) had not seen a case of Chagas disease in their practice; however, 72% also had never tested for it. The majority of knowledge-based questions about Chagas disease cardiac presentations were answered incorrectly, and 85% of providers expressed discomfort with recognizing cardiac presentations in children. Most respondents selected that they would not include Chagas disease on their differential diagnosis for presentations such as conduction anomalies, myocarditis and/or apical aneurysms, but would be more likely to include it if found in a Latin American immigrant. Of respondents, 87% agreed that they would be likely to attend a Chagas disease-related lecture. CONCLUSIONS: Pediatric cardiologists in the U.S. have seen very few cases of Chagas disease, albeit most have not sent testing or included it in their differential diagnosis. Most individuals agreed that education on Chagas disease would be worth-while.

Evaluation of cardiac function in the recipient twin in successfully treated twin-to-twin transfusion syndrome using a novel fetal speckle-tracking analysis.

INTRODUCTION: This study was designed to evaluate ventricular size, shape, and function in recipient twins following laser therapy for twin-twin transfusion syndrome (TTTS), using novel speckle-tracking techniques. METHODS: This retrospective study enrolled patients that underwent fetal laser surgery for TTTS and had fetal echocardiograms (FE) performed pre- and post-operatively (op), with adequate resolution in the 4-chamber view for analysis, using a speckle-tracking software, to compute the size, shape, and function of both the right (RV) and left (LV) ventricles. Values were indexed to published normal values. Pre- and post-laser Z-score values for each of the measurements were compared using the Student's t-test, with significance defined as P < 0.05. RESULTS: Fifteen TTTS candidate pregnancies that underwent laser therapy between 2010 and 2017, with adequate pre- and post-op FE, were selected for the analysis. Post-op FE at 28.5 ± 8.3 days showed a significant decrease in RV base dimension, increased LV base dimension, and improvements in many functional measurements: LV global and free wall strain, LV fractional area change, LV basal-apical fractional change, and LV and RV 24-segment fractional shortening (FS) of the basal segments. CONCLUSIONS: Cardiac remodeling, following laser surgery in TTTS recipient twins, was demonstrated in the basal portion of both the RV and LV with improved biventricular function.

Extracardiac Doppler indices predict perinatal mortality in fetuses with Ebstein anomaly and tricuspid valve dysplasia.

OBJECTIVES: Ebstein anomaly and tricuspid valve dysplasia (EA/TVD) carry high perinatal mortality. Past studies have focused on cardiac predictors of mortality; we sought to describe the fetal echo (FE) extracardiac Dopplers in this cohort and determine their association with perinatal mortality. METHOD: Fetuses with EA/TVD at 23 centers from 2005-2011 were included for retrospective study. Doppler pattern and velocity of the umbilical artery (UA), umbilical vein (UV), ductus venosus (DV), and middle cerebral artery (MCA) were collected. Bivariate and multivariate analyzes were performed. The primary outcome measure was perinatal mortality, defined as fetal demise or neonatal death. RESULTS: Of 190 cases that met eligibility criteria, alterations were seen in 50% of UA, 16% of UV, 48% of DV, and 8% of MCA Doppler indices on the last FE (median 27.4 weeks). Independent predictors of perinatal mortality included abnormal UA Doppler pattern of absence or reversed end diastolic flow (OR 9.7) and UV velocity z score <1 (OR 2.5), in addition to diagnosis <32 weeks (OR 4.2) and tricuspid valve (TV) annulus z score ≥6 (OR 5.3). CONCLUSION: Abnormal UA Doppler pattern and decreased UV velocity are independent predictors of perinatal mortality in EA/TVD fetuses and should be used to refine mortality risk and guide perinatal management.

Risk Factors for Mortality and Circulatory Outcome Among Neonates Prenatally Diagnosed With Ebstein Anomaly or Tricuspid Valve Dysplasia: A Multicenter Study.

Background In a recent multicenter study of perinatal outcome in fetuses with Ebstein anomaly or tricuspid valve dysplasia, we found that one third of live-born patients died before hospital discharge. We sought to further describe postnatal management strategies and to define risk factors for neonatal mortality and circulatory outcome at discharge. Methods and Results This 23-center, retrospective study from 2005 to 2011 included 243 fetuses with Ebstein anomaly or tricuspid valve dysplasia. Among live-born patients, clinical and echocardiographic factors were evaluated for association with neonatal mortality and palliated versus biventricular circulation at discharge. Of 176 live-born patients, 7 received comfort care, 11 died <24 hours after birth, and 4 had insufficient data. Among 154 remaining patients, 38 (25%) did not survive to discharge. Nearly half (46%) underwent intervention. Mortality differed by procedure; no deaths occurred in patients who underwent right ventricular exclusion. At discharge, 56% of the cohort had a biventricular circulation (13% following intervention) and 19% were palliated. Lower tricuspid regurgitation jet velocity (odds ratio [OR], 2.3 [1.1-5.0], 95% CI, per m/s; P=0.025) and lack of antegrade flow across the pulmonary valve (OR, 4.5 [1.3-14.2]; P=0.015) were associated with neonatal mortality by multivariable logistic regression. These variables, along with smaller pulmonary valve dimension, were also associated with a palliated outcome. Conclusions Among neonates with Ebstein anomaly or tricuspid valve dysplasia diagnosed in utero, a variety of management strategies were used across centers, with poor outcomes overall. High-risk patients with low tricuspid regurgitation jet velocity and no antegrade pulmonary blood flow should be considered for right ventricular exclusion to optimize their chance of survival.

Impact of Confounding on Cost, Survival, and Length-of-Stay Outcomes for Neonates with Hypoplastic Left Heart Syndrome Undergoing Stage 1 Palliation Surgery.

The objective of this analysis was to update trends in LOS and costs by survivorship and ECMO use among neonates with hypoplastic left heart syndrome (HLHS) undergoing stage 1 palliation surgery using 2016 data from the Healthcare Cost and Utilization Project Kids' Inpatient Database. We identified neonates ≤ 28 days old with HLHS undergoing Stage 1 surgery, defined as a Norwood procedure with modified Blalock-Taussig (BT) shunt, Sano modification, or both. Multivariable regression with year random effects was used to compare LOS and costs by hospital region, case volume, survivorship, and ECMO vs. no ECMO. An E-value analysis, an approach for conducting sensitivity analysis for unmeasured confounding, was performed to determine if unmeasured confounding contributed to the observed effects. Significant differences in total costs, LOS, and mortality were noted by hospital region, ECMO use, and sub-analyses of case volume. However, other than ECMO use and mortality, the maximum E-value confidence interval bound was 1.71, suggesting that these differences would disappear with an unmeasured confounder 1.71 times more associated with both the outcome and exposure (e.g., socioeconomic factors, environment, etc.) Our findings confirm previous literature demonstrating significant resource utilization among Norwood patients, particularly those undergoing ECMO use. Based on our E-value analysis, differences by hospital region and case volume can be explained by moderate unobserved confounding, rather than a reflection of the quality of care provided. Future analyses on surgical quality must account for unobserved factors to provide meaningful information for quality improvement.

Procedural, pregnancy, and short-term outcomes after fetal aortic valvuloplasty.

OBJECTIVES: We aimed to evaluate the effect of technical aspects of fetal aortic valvuloplasty (FAV) on procedural risks and pregnancy outcomes. BACKGROUND: FAV is performed in cases of severe mid-gestation aortic stenosis with the goal of preventing hypoplastic left heart syndrome (HLHS). METHODS: The International Fetal Cardiac Intervention Registry was queried for fetuses who underwent FAV from 2002 to 2018, excluding one high-volume center. RESULTS: The 108 fetuses had an attempted cardiac puncture (mean gestational age [GA] 26.1 ± 3.3 weeks). 83.3% of attempted interventions were technically successful (increased forward flow/new aortic insufficiency). The interventional cannula was larger than 19 g in 70.4%. More than one cardiac puncture was performed in 25.0%. Intraprocedural complications occurred in 48.1%, including bradycardia (34.1%), pericardial (22.2%) or pleural effusion (2.7%) requiring drainage, and balloon rupture (5.6%). Death within 48 hr occurred in 16.7% of fetuses. Of the 81 patients born alive, 59 were discharged home, 34 of whom had biventricular circulation. More than one cardiac puncture was associated with higher complication rates (p < .001). Larger cannula size was associated with higher pericardial effusion rates (p = .044). On multivariate analysis, technical success (odds ratio [OR] = 10.9, 95% confidence interval [CI] = 2.2-53.5, p = .003) and later GA at intervention (OR = 1.5, 95% CI = 1.2-1.9, p = .002) were associated with increased odds of live birth. CONCLUSIONS: FAV is an often successful but high-risk procedure. Multiple cardiac punctures are associated with increased complication and fetal mortality rates. Later GA at intervention and technical success were independently associated with increased odds of live birth. However, performing the procedure later in gestation may miss the window to prevent progression to HLHS.

Delivery room emergencies in critical congenital heart diseases.

Transition from fetal to postnatal life is a complex process. Even in the absence of congenital heart disease, about 4-10% of newborns require some form of assistance in the delivery room. Neonates with complex congenital heart disease should be expected to require significant intervention and thus the resuscitation team must be well prepared for such a delivery. Prenatal assessment including fetal and maternal health in general and detailed information on fetal heart structure, function and hemodynamics in particular are crucial for planning the delivery and resuscitation. In addition, understanding the impact of cardiac structural anomaly and associated altered blood flow on early postnatal transition is essential for success of resuscitation in the delivery room. In this article, we will briefly review transitional circulation focusing on altered hemodynamics of the complex congenital heart diseases and then discuss the process of preparing for these high-risk deliveries. Finally, we will review the pathophysiology resulting from the cardiac structural anomaly with resultant altered fetal circulation and discuss delivery room management of specific critical congenital heart diseases.

Prenatal diagnosis and management of congenital complete heart block.

Congenital complete heart block (CCHB) is a life-threatening medical condition in the unborn fetus with insufficiently validated prenatal interventions. Maternal administration of medications aimed at decreasing the immune response in the fetus and beta-agonists intended to increase fetal cardiac output have shown only marginal benefits. Anti-inflammatory therapies cannot reverse CCHB, but may decrease myocarditis and improve heart function. Advances in prenatal diagnosis and use of strict surveillance protocols for delivery timing have demonstrated small improvements in morbidity and mortality. Ambulatory surveillance programs and wearable fetal heart rate monitors may afford early identification of evolving fetal heart block allowing for emergent treatment. There is also preliminary data suggesting a roll for prevention of CCHB with hydroxychloroquine, but the efficacy and safety is still being studied. To date, intrauterine fetal pacing has not been successful due to the high-risk invasive placement techniques and potential problems with lead dislodgement. The development of a fully implantable micropacemaker via a minimally invasive approach has the potential to pace fetal patients with CCHB and thus delay delivery and allow fetal hydrops to resolve. The challenge remains to establish accepted prenatal interventions capable of successfully managing CCHB in utero until postnatal pacemaker placement is successfully achieved.

Differences in Right Ventricular Physiologic Response to Chronic Volume Load in Patients with Repaired Pulmonary Atresia Intact Ventricular Septum/Critical Pulmonary Stenosis Versus Tetralogy of Fallot.

BACKGROUND: Patients with pulmonary atresia with intact ventricular septum and critical pulmonary stenosis (PAIVS/CPS) have wide variation in right ventricle (RV) size, systolic function, and diastolic function at birth. Establishment of antegrade pulmonary blood flow creates the potential for RV dilation from chronic pulmonary insufficiency. Future surgical decisions are based on RV size and function, largely supported by longitudinal studies of patients with Tetralogy of Fallot (TOF). Given potential differences in RV physiology and lack of similar data in PAIVS/CPS, the objective of this study was to determine differences in RV size, systolic function, and diastolic function between patients with PAIVS/CPS versus TOF. METHODS: We retrospectively collected cardiovascular magnetic resonance (CMR) data in 27 patients with PAIVS/CPS (ages 13.3 ± 8.8 years) and 78 with TOF (11.4 ± 5.4 years). RV volumes, ejection fraction (EF), regurgitant fraction, end-diastolic forward flow across the pulmonary valve, and right atrial cross-sectional area were calculated. RESULTS: There was no difference between the groups in RV end-diastolic volume (RVEDVi), RVEF, or pulmonary regurgitation. RVEF tended to decrease in TOF when RVEDVi exceeded 164 ml/m2. In PAIVS/CPS, RVEDVi less frequently reached 164 ml/m2 and was not associated with RVEF. There was worse RV diastolic dysfunction in PAIVS/CPS, with 1.5 times larger right atrial area and two times higher pulmonary end-diastolic forward flow (p < 0.0001). CONCLUSIONS: Patients with PAIVS/CPS have similar RV size, systolic function, and pulmonary regurgitation as TOF. However, impaired RV diastolic function may limit extremes of RV dilatation and impact long-term management of PAIVS/CPS.

Minimally Invasive Implantation of a Micropacemaker Into the Pericardial Space.

BACKGROUND: Permanent cardiac pacemakers require invasive procedures with complications often related to long pacemaker leads. We are developing a percutaneous pacemaker for implantation of an entire pacing system into the pericardial space. METHODS: Percutaneous micropacemaker implantations were performed in 6 pigs (27.4-34.1 kg) using subxyphoid access to the pericardial space. Modifications in the implantation methods and hardware were made after each experiment as the insertion method was optimized. In the first 5 animals, nonfunctional pacemaker devices were studied. In the final animal, a functional pacemaker was implanted. RESULTS: Successful placement of the entire nonfunctional pacing system into the pericardial space was demonstrated in 2 of the first 5 animals, and successful implantation and capture was achieved using a functional system in the last animal. A sheath was developed that allows retractable features to secure positioning within the pericardial space. In addition, a miniaturized camera with fiberoptic illumination allowed visualization of the implantation site before electrode insertion into myocardium. All animals studied during follow-up survived without symptoms after the initial postoperative period. CONCLUSIONS: A novel micropacemaker system allows cardiac pacing without entering the vascular space or surgical exposure of the heart. This pericardial pacemaker system may be an option for a large number of patients currently requiring transvenous pacemakers but is particularly relevant for patients with restricted vascular access, young children, or those with congenital heart disease who require epicardial access.

Neonatal Outcomes in Total Anomalous Pulmonary Venous Return: The Role of Prenatal Diagnosis and Pulmonary Venous Obstruction.

The objective of this study is to evaluate neonatal outcomes of total anomalous pulmonary venous return (TAPVR) and identify fetal echocardiography findings associated with preoperative pulmonary venous obstruction (PPVO). This retrospective study evaluated TAPVR cases from 2005 to 2014 for preoperative and postoperative outcomes based on prenatal diagnosis, PPVO, and heterotaxy syndrome. Fetal pulmonary and vertical vein Dopplers were analyzed as predictors of PPVO. Of 137 TAPVR cases, 12% were prenatally diagnosed; 60% had PPVO, and 21% had heterotaxy. Of the prenatally diagnosed patients, 63% also had heterotaxy. TAPVR repair was performed in 135 cases and survival to discharge was 82% (112/137). Heterotaxy was the only independent predictor of mortality on multiple regression analysis [OR 5.5 (CI 1.3-16.7), p = 0.02]. PPVO was associated with preoperative acidosis, need for inhaled nitric oxide, and more emergent surgery, but not postoperative mortality. Fetal vertical vein Doppler peak velocity > 0.74 m/s mmHg predicted PPVO (93% sensitivity; 83% specificity) while pulmonary vein Doppler did not. TAPVR has severe neonatal morbidity and mortality with low prenatal diagnosis rates in the absence of heterotaxy. Patients with obstructed TAPVR had greater preoperative morbidity, but only heterotaxy was independently associated with increased postoperative mortality. Vertical vein velocity helped prenatally identify those at risk of PPVO.

Fetal echocardiography for planning perinatal and delivery room care of neonates with congenital heart disease.

Fetal echocardiography facilitates the prenatal diagnosis of infants with congenital heart disease (CHD) and through sequential examinations, allows assessment of fetal hemodynamics and cardiovascular status from the time of diagnosis to delivery. Fetal cardiologists have created diagnostic protocols aimed at risk stratifying severity and potential postnatal compromise in fetuses with CHD, and identifying those who may require special intervention at birth or within the first days of life. In this article, we review fetal cardiovascular physiology, the progression of CHD in utero and fetal echocardiographic findings used for risk stratification of newborns with CHD, as well as some of the basic principles of planning for the neonatal resuscitation and initial transitional care of these complex newborns.

Recipient Twin Circular Shunt Physiology Before Fetal Laser Surgery: Survival and Risks for Postnatal Right Ventricular Outflow Tract Obstruction.

OBJECTIVES: To evaluate risk for congenital heart disease (CHD) in recipient twins with circular shunt physiology (CSP). METHODS: This prospective study enrolled twin-twin transfusion syndrome (TTTS) cases from 2006 to 2015. Fetal echocardiography (FE) was performed before laser surgery when cardiac involvement was suspected. Diagnosis of recipient twin CSP required tricuspid and pulmonary regurgitation, right ventricular dysfunction, and flow reversal in the ductus arteriosus. Outcomes were assessed at 30 days after birth. RESULTS: Of the 496 TTTS pregnancies, 20 (4%) met the criteria for CSP. Among those born alive, who had documented cardiac outcomes (n = 457), patients with CSP were more likely to have CHD, specifically right ventricular outflow tract obstruction (5 of 18 [27.8%] versus 22 of 439 [5.0%], odd ratio [OR] 7.29, 95% confidence interval [CI] 2.05-24.72, P = .0025). Of the recipient twins with preoperative FE (n = 259, 52%) who were born alive and had documented cardiac outcomes (n = 242), those with CSP were still more likely to have right ventricular outflow tract obstruction (5 of 18 [27.8%] versus 14 of 224 [6.3%], OR 5.77, CI 1.54-20.92, P = .0077). With both analyses, twins with CSP had higher Quintero stage, but similar patient characteristics and 30-day mortality compared with those without CSP. Subgroup analyses of the CSP cohort identified no differences in preoperative characteristics or FE findings predictive of CHD. CONCLUSIONS: Recipient twins with preoperative CSP were at increased risk for postnatal right ventricular outflow tract obstruction, but appeared to have comparable survival after fetal laser surgery despite these dramatic pathophysiological prenatal findings. Preoperative FE in TTTS remains important for prediction of postnatal CHD.

Analytical Modeling for Computing Lead Stress in a Novel Epicardial Micropacemaker.

Implantation and maintenance of a permanent cardiac pacing system in children remains challenging due to small patient size, congenital heart defects and somatic growth. We are developing a novel epicardial micropacemaker for children that can be implanted on the epicardium within the pericardial space via a minimally-invasive technique. The key design configurations include a novel open-coiled lead in which living tissue replaces the usual polymeric support for the coiled conductor. To better understand and be able to predict the behavior of the implanted lead, we performed a radiographic image-based modeling study on a chronic animal test. We report a pilot study in which two mechanical dummy pacemakers with epicardial leads were implanted into an adult pig model via a minimally invasive approach. Fluoroscopy was obtained on the animal on Post-Operative Days #9, #35 and #56 (necropsy). We then constructed an analytic model to estimate the in vivo stress conditions on the open-coil lead based on the analysis of orthogonal biplane radiographic images. We obtained geometric deformation data of the implanted lead including elongation magnitudes and bending radii from sequenced films of cardiac motion cycles. The lead stress distribution was investigated on each film frame and the point of maximum stress (Mean Stress = 531.4 MPa; Alternating Stress = ± 216.4 MPa) was consistently where one of the leads exited the pericardial space, a deployment that we expected to be unfavorable. These results suggest the modeling approach can provide a basis for further design optimization. More animal tests and modeling will be needed to validate whether the novel lead design could meet the requirements to withstand ~200 million cardiac motion cycles over 5 years.