Hemodynamic and anatomic changes after fetal aortic valvuloplasty are associated with procedural success and postnatal biventricular circulation.

BACKGROUND: There are minimal data characterizing the trajectory of left heart growth and hemodynamics following fetal aortic valvuloplasty (FAV). METHODS: This retrospective study included patients who underwent FAV between 2000 and 2019, with echocardiograms performed pre-FAV, immediately post-FAV, and in late gestation. RESULTS: Of 118 fetuses undergoing FAV, 106 (90%) underwent technically successful FAV, of which 55 (52%) had biventricular circulation. Technically successful FAV was associated with improved aortic valve growth (p < 0.001), sustained antegrade aortic arch (AoA) flow (p = 0.02), improved mitral valve (MV) inflow pattern (p = 0.002), and favorable patent foramen ovale (PFO) flow pattern (p = 0.004) from pre-FAV to late gestation. Compared to patients with univentricular outcome, patients with biventricular outcome had less decrement in size of the left ventricle (LV) (p < 0.001) and aortic valve (p = 0.005), as well as more physiologic PFO flow (p < 0.001) and antegrade AoA flow (p < 0.001) from pre-FAV to late gestation. In multivariable analysis, echocardiographic predictors of biventricular outcome were less decline in LV end diastolic dimension (p < 0.001), improved PFO flow (p = 0.004), and sustained antegrade AoA flow (p = 0.002) from pre-FAV to late gestation. CONCLUSION: Stabilization of left heart growth and improved hemodynamics following successful FAV through late gestation are associated with postnatal biventricular circulation.

Contrast volume to estimated glomerular filtration rate ratio for prediction of contrast-induced acute kidney injury after cardiac catheterization in adults with congenital heart disease.

BACKGROUND: Adults with congenital heart disease (ACHD) are vulnerable to contrast-induced acute kidney injury (CI-AKI) after cardiac catheterization. The aim of this study was to identify risk factors for clinically significant CI-AKI and evaluate the predictive value of contrast volume to estimated glomerular filtration rate ratio (V/eGFR) for the risk of CI-AKI following catheterization in the ACHD population. METHODS: ACHD patients who underwent catheterization at Boston Children's hospital between 1/2011 and 1/2017 were retrospectively analyzed. CI-AKI was defined as an increase in serum creatinine ≥0.3 mg/dL within 48 hr or ≥1.5 times baseline within 7 days of procedure. Controls without CI-AKI were matched for calendar year of catheterization with cases using a 3:1 ratio. RESULTS: Of 453 catheterizations meeting inclusion criteria, 27 catheterizations (5.9%) were complicated by CI-AKI, with dialysis being used to manage renal dysfunction in five of these events. Older age, male gender, admission prior to catheterization, and V/eGFR ratio were found to be related to risk of CI-AKI. Patients with a V/eGFR ≥ 2.6 had a significantly higher risk of CI-AKI (OR = 6.4; 95% CI = 2.0-20.4; P = 0.002). Survival at 3 years post-catheterization, was significantly shorter for CI-AKI cases compared to controls (49% versus 97%; P < 0.001) even in those with return to baseline renal function prior to discharge (60% versus 97%, P < 0.001). CONCLUSION: In ACHD patients undergoing cardiac catheterization, a higher V/eGFR ratio is a strong predictor of clinically significant CI-AKI. Development of CI-AKI is a poor prognostic indicator and is associated with decreased survival in this population.

Echocardiographic predictors of neonatal illness severity in fetuses with critical left heart obstruction with intact or restrictive atrial septum.

BACKGROUND: Neonates with critical left heart obstruction and intact atrial septum (IAS) or restrictive atrial septum (RAS) are at risk for hypoxia within hours of birth and remain a group at high risk for mortality. METHODS: Prenatally diagnosed fetuses with critical left heart obstruction and IAS or RAS with follow-up from January 1, 2005, to February 14, 2017, were included. Primary outcome was a composite measure of severe neonatal illness (pH < 7.15, venous pH < 7.10, bicarbonate < 16 mmol/L, lactic acid > 5 mmol/L, or median oxygen saturation < 60% within 2 hours of birth). RESULTS: Of 68 live born fetuses, 52 (76.5%) had hypoplastic left heart syndrome, 14 (20.5%) had critical aortic stenosis, and two (3%) had complex anatomy with mitral stenosis/atresia. There were 27 (39.7%) fetuses with IAS and 41 (60.3%) with RAS. Severe neonatal illness was present in 36 (52.9%). The strongest discriminators for severe neonatal illness were a pulmonary vein A:R VTI ≤ 2.7 (P < 0.001, AUC 0.93) and larger pulmonary vein diameter (P = 0.025, AUC 0.77). A:R VTI ≤ 2.7 predicted death or transplant (log-rank P = 0.03). CONCLUSIONS: In neonates with hypoplastic left heart syndrome and IAS or RAS, A:R VTI ≤ 2.7 is predictive of severe neonatal instability. This threshold can help guide resource planning, delivery management, and improve fetal intervention criteria.

Late-term development of an atrial defect and thrombus formation after device fracture following successful transcatheter closure of an atrial septal defect with a STARFlex device.

Development of a new defect following transcatheter closure of an atrial septal defect has yet to be reported. In this study, we present an acutely successful atrial septal defect closure with a STARFlex device, resulting in surgical explantation after discovery of device fracture, thrombus formation, and a second atrial defect 5 years after catheterisation. This case highlights the need for ongoing device surveillance, even in late follow-up.

Transcatheter balloon dilation for recurrent right ventricular outflow tract obstruction following valve-sparing repair of tetralogy of Fallot.

BACKGROUND: Valve-sparing repair in patients with tetralogy of Fallot (TOF) carries the risk of residual or recurrent right ventricular outflow tract (RVOT) obstruction, which is often treated with transcatheter balloon dilation (BD). The outcomes and associated complications of BD of the RVOT in this scenario remain unknown. METHODS: Retrospective review of the records of the Department of Cardiology at Boston Children's Hospital from 2000 to 2013 was performed. RESULTS: 34 patients had initial valve-sparing repair of tetralogy of Fallot followed by BD of the RVOT during the study period. Following BD, the RVOT gradient decreased from a median of 43 mm Hg (range 13 to 79 mm Hg) to 28 mm Hg (range 0 to 73 mm Hg) (P < 0.001). Freedom from reintervention was 64% at 1 year and 46% at 3 years. Trivial to mild PR pre-BD was present in 56% (n = 19) of patients and decreased to 37% (n = 11) post-BD. Exclusively valvar obstruction was associated with a longer freedom from reintervention (P = 0.05), while a ratio of RV pressure to aortic systolic pressure pre-BD of >1 and a final RVOT gradient of ≥40 post-BD were associated with shorter freedom from reintervention (P < 0.001). CONCLUSION: BD in patients with recurrent RVOT obstruction following valve-sparing repair of TOF acutely reduces the RVOT gradient, but commonly results in increased PR and is associated with a high reintervention rate. Patients with stenosis solely at the level of the valve had a better response to this type of intervention.

Reducing patient radiation exposure during paediatric SVT ablations: use of CARTO® 3 in concert with "ALARA" principles profoundly lowers total dose.

BACKGROUND: "ALARA--As Low As Reasonably Achievable" protocols reduce patient radiation dose. Addition of electroanatomical mapping may further reduce dose. METHODS: From 6/11 to 4/12, a novel ALARA protocol was utilised for all patients undergoing supraventricular tachycardia ablation, including low frame rates (2-3 frames/second), low fluoro dose/frame (6-18 nGy/frame), and other techniques to reduce fluoroscopy (ALARA). From 6/12 to 3/13, use of CARTO® 3 (C3) with "fast anatomical mapping" (ALARA+C3) was added to the ALARA protocol. Intravascular echo was not utilised. Demographics, procedural, and radiation data were analysed and compared between the two protocols. RESULTS: A total of 75 patients were included: 42 ALARA patients, and 33 ALARA+C3 patients. Patient demographics were similar between the two groups. The acute success rate in ALARA was 95%, and 100% in ALARA+C3; no catheterisation-related complications were observed. Procedural time was 125.7 minutes in the ALARA group versus 131.4 in ALARA+C3 (p=0.36). Radiation doses were significantly lower in the ALARA+C3 group with a mean air Kerma in ALARA+C3 of 13.1±28.3 mGy (SD) compared with 93.8±112 mGy in ALARA (p<0.001). Mean dose area product was 92.2±179 uGym2 in ALARA+C3 compared with 584±687 uGym2 in ALARA (p<0.001). Of the 33 subjects (42%) in the ALARA+C3 group, 14 received ⩽1 mGy exposure. The ALARA+C3 dosages are the lowest reported for a combined electroanatomical-fluoroscopy technique. CONCLUSIONS: Addition of CARTO® 3 to ALARA protocols markedly reduced radiation exposure to young people undergoing supraventricular tachycardia ablation while allowing for equivalent procedural efficacy and safety.

Pediatric patient radiation dosage during endomyocardial biopsies and right heart catheterization using a standard "ALARA" radiation reduction protocol in the modern fluoroscopic era.

BACKGROUND: Surveillance endomyocardial biopsy (EMB) with right heart catheterization (RHC) is the standard of care for the assessment of post cardiac transplantation rejection. This procedure has traditionally relied upon fluoroscopy, which exposes both patient and staff to the risks of ionizing radiation. These risks may be of particular concern in the transplant patient who must undergo many such procedures lifelong. We present data on a new "ALARA - As Low As Reasonably Achievable" protocol to reduce radiation exposure during the performance of RHC with EMB. METHODS: All cardiac transplantation patients < 21 years of age who underwent RHC with EMB at The Children's Hospital at Montefiore from 6/11-12/11 were included. EMB was performed after all right heart pressures including wedge pressure and thermodilution cardiac output were measured. A novel ALARA protocol consisting of multiple features including ultra-low frame rates (2-3 fps), low fluoro dose/frame (10-18 nGy/frame), use of the "air-gap" technique for patients < 20 kg, and multiple other techniques aimed at minimizing use of fluoroscopy were employed in all cases. Demographics, procedural data and patient radiation exposure levels were collected and analyzed. RESULTS: 18 patients underwent 45 surveillance RHC with EMB in the study period and were the subject of this analysis. The mean age was 5.9 ± 6.1 years, weight was 20.4 kg ± 16.6 kg, and BSA was 0.75 ± 45 m(2) . PA fluoroscopy was used exclusively in 45/45. Vascular access was RFV (21/45; 47%), RIJV (17/45; 38%), LFV (4/45; 9%) and LIJV (3/45; 7%). The median number of EMB specimens obtained was 5 (range, 4-7). The median fluoroscopy time was 3.7 min (range, 1.2-9). The median air Kerma product (K) was 1.4 mGy (range, 0.4-14), and dose area product (DAP) was 15.8 uGym(2) (range, 3.5-144.5). The K and DAP are substantially lower than any prior published data for RHC/EMB in this patient group. There were no procedural complications. CONCLUSIONS: The use of a novel ALARA protocol for RHC and EMB in pediatric cardiac transplantation patients markedly reduced radiation exposure to levels far below any previously reported values without negatively affecting the safety or efficacy of these procedures.

Cleft closure and other predictors of contemporary outcomes after atrioventricular canal repair in patients with parachute left atrioventricular valve.

OBJECTIVES: Parachute left atrioventricular valve (LAVV) complicates atrioventricular septal defect (AVSD) repair. We evaluate outcomes of AVSD patients with parachute LAVV and identify risk factors for adverse outcomes. METHODS: We evaluated all patients undergoing repair of AVSD with parachute LAVV from 2012 to 2021. The primary outcome was a composite of time-to-death, LAVV reintervention and development of greater than or equal to moderate LAVV dysfunction (greater than or equal to moderate LAVV stenosis and/or LAVV regurgitation). Event-free survival for the composite outcome was estimated using Kaplan-Meier methodology and competing risks analysis. Cox proportional hazards regression was used to identify predictors of the primary outcome. RESULTS: A total of 36 patients were included with a median age at repair of 4 months (interquartile range 2.3-5.5 months). Over a median follow-up of 2.6 years (interquartile range 1.0-5.6 years), 6 (17%) patients underwent LAVV reintervention. All 6 patients who underwent LAVV reintervention had right-dominant AVSD. Sixteen patients (44%) met the composite outcome, and all did so within 2 years of initial repair. Transitional AVSD (versus complete), prior single-ventricle palliation, leaving the cleft completely open and greater than or equal to moderate preoperative LAVV regurgitation were associated with a higher risk of LAVV reintervention in univariate analysis. In multivariate analysis, leaving the cleft completely open was associated with the composite outcome. CONCLUSIONS: Repair of AVSD with parachute LAVV remains a challenge with a significant burden of LAVV reintervention and dysfunction in medium-term follow-up. Unbalanced, right-dominant AVSDs are at higher risk for LAVV reintervention. Leaving the cleft completely open might independently predict poor overall outcomes and should be avoided when possible. CLINICAL TRIAL REGISTRATION NUMBER: IRB-P00041642.

Reducing patient radiation dosage during pediatric SVT ablations using an "ALARA" radiation reduction protocol in the modern fluoroscopic era.

BACKGROUND: Ablation for supraventricular tachycardia (SVT) relies upon fluoroscopy (fluoro), which exposes the patient and staff to ionizing radiation. The objective of this work was to present a new "ALARA--As Low As Reasonably Achievable" protocol with alterations to fluoroscopic x-ray parameters to reduce dose without an electroanatomical (EAM) approach. METHODS: All patients <21 years of age undergoing ablation of SVT at our institution from June 2011 to April 2012 were included. EAM was not utilized in any case. An ALARA protocol of low frame rates (2 or 3 fps), low fluoro dose/frame (10-18 nGy/frame), and other techniques aimed at reducing use of fluoroscopy were employed. Demographics, procedural, and radiation data were analyzed. RESULTS: Forty-two patients underwent ablation and were studied. Median age was 14.1 years (range 4.8-21.1 years), weight was 51 kg (range 18.2-75 kg), and body surface area was 1.51 m(2) (range 0.72- 1.94 m(2)). Seventeen (41%) had Wolff-Parkinson-White syndrome, 14 (33%) atrioventricular nodal reentrant tachycardia, and 11 (26%) concealed pathways. Median procedural time was 114 minutes (57-246 minutes). Median dose area product (DAP) for posterioanterior and lateral fluoroscopy was 343.2 uGym(2) (range 38.2-3,172 uGym(2)); the median air Kerma product (K) was 45.4 mGy (range 6.7-567.5 mGy). DAP and K are lower than prior data from EAM and fluoroscopy techniques. The acute success rate was 95%; no procedural complications. CONCLUSIONS: An ALARA protocol for ablation of SVT reduced radiation to below levels previously reported for combined EAM/fluoro approaches. Success rates were excellent with no complications and without the costs of EAM.

Left atrioventricular valve repair after primary atrioventricular canal surgery: Predictors of durability.

OBJECTIVE: Acute outcomes after atrioventricular canal defects (AVCD) surgery in the current era are excellent; yet despite surgical advances, ∼15% of patients require future left atrioventricular valve (LAVV) repair. Among patients with AVC who undergo LAVV repair after primary AVC surgery, we sought to characterize the durability of these repairs. Specifically, we aimed to determine predictors for reintervention following an LAVV repair in patients with repaired AVCD, with a focus on postoperative transesophageal echocardiography (TEE). METHODS: We reviewed all patients undergoing LAVV repair (after a primary AVCD surgery) at Boston Children's Hospital between 2010 and 2020. Competing risk analysis was performed to evaluate cumulative incidence of LAVV reinterventions. Predictors of LAVV reintervention were evaluated using multivariable Cox regression. RESULTS: A total of 137 LAVV repairs following primary AVCD surgery were performed in 113 patients. Median age and weight at LAVV repair were 25 months (interquartile range, 12-76 months) and 11.1 kg (interquartile range, 7.8-19.4 kg). Original anatomy was complete AVCD in 87 (63%), transitional AVCD in 27 (20%), and partial AVCD in 23 (17%) cases. Over a median follow-up of 12 months (interquartile range, 1.3 months-4 years), 47 (34%) of the LAVV repairs required LAVV reintervention. Reinterventions included a total of 27 LAVV re-repairs and 20 LAVV replacements. In multivariable analysis, age at LAVV repair younger than 72 months, partial AVCD anatomy, left ventricle dysfunction, mean LAVV stenosis gradient ≥5 mm Hg, and multiple jets of regurgitation on postoperative LAVV repair TEE were associated with LAVV reintervention. Grade of LAVV regurgitation on postoperative TEE was not an independent risk factor, but reintervention rates were high when residual LAVV stenosis gradient was ≥5 mm Hg and residual mild LAVV regurgitation was present on postoperative TEE (47%) and even higher when residual LAVV stenosis gradient was ≥5 mm Hg and LAVV regurgitation was greater than mild (73%). CONCLUSIONS: Reintervention rates remain high for LAVV repairs that occur after primary AVCD surgery, particularly for patients with LAVV stenosis gradient ≥5 mm Hg and mild or greater LAVV regurgitation on postoperative TEE.

Comparison of coronary artery measurements between echocardiograms and cardiac CT in Kawasaki disease patients with aneurysms.

BACKGROUND: American Heart Association (AHA) guidelines for management of Kawasaki disease (KD) rely on coronary artery (CA) z-scores from echocardiograms. Compared with echocardiography, cardiac CT (CCT) offers better visualization of distal segments and evaluation for thrombosis and stenosis. Despite increasing use of CCT in KD, CA z-scores for CCT are not available and measurement concordance between imaging modalities is a critical knowledge gap. METHODS: We retrospectively reviewed KD patients with CA aneurysms who had concurrent echocardiography and CCT between 2016 and 2020. Patients were included if they had history of CA z-scores of ≥3 on echocardiography during their clinical course. Agreement between CCT and echocardiography was assessed using Bland-Altman analysis. RESULTS: Paired CCT and echocardiography studies were available in 18 patients (21 studies). The largest CA aneurysms were large/giant (z-score ≥10) in 14 studies, medium (z-score ≥5, <10) in 3 studies, and small (z score ≥2.5, <5) in 2 studies. Intra- and inter-observer reliability for CCT measurements were high for all CA segments (ICC 99.7% and 98.6%). For the LMCA, proximal LAD and proximal and distal RCA there was high correlation between echocardiogram and CCT absolute measurements with wider variation between modalities for the distal LAD and circumflex. Overall, CCT measurements tended to be smaller than echocardiogram measurements, and led to a lower AHA z-score risk classification in 24% of studies. CONCLUSION: CCT and echocardiography have high agreement for absolute measurements of proximal CA segments, but more measurement discrepancy exists for distal CA segments with bias toward lower dimensions on CCT.

Long-term outcomes of truncus arteriosus repair: A modulated renewal competing risks analysis.

OBJECTIVE: In this study, we sought to identify independent risk factors for mortality and reintervention after early surgical correction of truncus arteriosus using a novel statistical method. METHODS: Patients undergoing neonatal/infant truncus arteriosus repair between January 1984 and December 2018 were reviewed retrospectively. An innovative statistical strategy was applied integrating competing risks analysis with modulated renewal for time-to-event modeling. RESULTS: A total of 204 patients were included in the study. Mortality occurred in 32 patients (15%). Smaller right ventricle to pulmonary artery conduit size and truncal valve insufficiency at birth were significantly associated with overall mortality (right ventricle to pulmonary artery conduit size: hazard ratio, 1.34; 95% confidence interval, 1.08-1.66, P = .008; truncal valve insufficiency: hazard ratio, 2.5; 95% confidence interval, 1.13-5.53, P = .024). truncal valve insufficiency at birth, truncal valve intervention at index repair, and number of cusps (4 vs 3) were associated with truncal valve reoperations (truncal valve insufficiency: hazard ratio, 2.38; 95%, confidence interval, 1.13-5.01, P = .02; cusp number: hazard ratio, 6.62; 95% confidence interval, 2.54-17.3, P < .001). Right ventricle to pulmonary artery conduit size 11 mm or less was associated with a higher risk of early catheter-based reintervention (hazard ratio, 1.54; 95% confidence interval, 1.04-2.28, P = .03) and reoperation (hazard ratio, 1.96; 95% confidence interval, 1.33-2.89, P = .001) on the right ventricle to pulmonary artery conduit. CONCLUSIONS: Smaller right ventricle to pulmonary artery conduit size and truncal valve insufficiency at birth were associated with overall mortality after truncus arteriosus repair. Quadricuspid truncal valve, the presence of truncal valve insufficiency at the time of diagnosis, and truncal valve intervention at index repair were associated with an increased risk of reoperation. The size of the right ventricle to pulmonary artery conduit at index surgery is the single most important factor for early reoperation and catheter-based reintervention on the conduit.

Tricuspid valve repair concomitant with the Norwood operation among babies with hypoplastic left heart syndrome.

OBJECTIVES: Among patients with hypoplastic left heart syndrome (HLHS), tricuspid valve regurgitation (TR) portends a poor prognosis. Our goal was to describe the outcomes of tricuspid valve reconstruction (TVR) concomitant with the Norwood operation and using two-dimensional echocardiography and evaluate the structural factors associated with successful functional correction. METHODS: We performed a retrospective, single-centre study of patients with HLHS undergoing TVR at the time of the Norwood operation. Structural echocardiographic parameters were compared between patients with successful correction (≤ mild TR) and those with ≥ moderate regurgitation at discharge. Preoperative dimensions of matched HLHS controls with ≤ trivial TR were used as a reference. RESULTS: Of 205 patients with HLHS undergoing the Norwood operation, 18 patients had a concomitant TVR. Ten (56%) patients had an improved TR grade postoperatively, 8 (44%) of whom had ≤ mild TR at discharge. Improvement in TR grade (P = 0.001) and having ≤ mild TR at discharge (P = 0.011) were associated with an improved reintervention and TR-free survival. Patients with successful functional correction had smaller preoperative tricuspid annulus lateral dimensions (P = 0.023), tricuspid valve area (P = 0.007) and right ventricle mid-width (P = 0.064). Preoperatively, the successful TVR cases tended to have had higher anterior leaflet excursion (80 ± 20 vs 55 ± 11, P = 0.010), and a higher proportion of anterior leaflet prolapse (63% vs 10%, P = 0.043) compared to cases where TVR was not successful. CONCLUSIONS: Patients with HLHS with significant tricuspid regurgitation undergoing the stage 1 operation were more likely to have successful concomitant tricuspid valve repair if they had less tricuspid annular dilation, less-severe RV enlargement and predominantly anterior leaflet prolapse. Successful tricuspid valve repair was associated with improved mid- and long-term outcomes.

Long-Term Fate of the Truncal Valve.

Background Long-term survival in patients with truncus arteriosus is favorable, but there remains significant morbidity associated with ongoing reinterventions. We aimed to study the long-term outcomes of the truncal valve and identify risk factors associated with truncal valve intervention. Methods and Results We retrospectively reviewed patients who underwent initial truncus arteriosus repair at our institution from 1985 to 2016. Analysis was performed on the 148 patients who were discharged from the hospital and survived ≥30 days postoperatively using multivariable competing risks Cox regression modeling. Median follow-up time was 12.6 years (interquartile range, 5.0-22.1 years) after discharge from full repair. Thirty patients (20%) underwent at least one intervention on the truncal valve during follow-up. Survival at 1, 10, and 20 years was 93.1%, 87.0%, and 80.9%, respectively. The cumulative incidence of any truncal valve intervention by 20 years was 25.6%. Independent risk factors for truncal valve intervention included moderate or greater truncal valve regurgitation (hazard ratio [HR], 4.77; P<0.001) or stenosis (HR, 4.12; P<0.001) before full truncus arteriosus repair and moderate or greater truncal valve regurgitation at discharge after full repair (HR, 8.60; P<0.001). During follow-up, 33 of 134 patients (25%) progressed to moderate or greater truncal valve regurgitation. A larger truncal valve root z-score before truncus arteriosus full repair and during follow-up was associated with worsening truncal valve regurgitation. Conclusions Long-term rates of truncal valve intervention are significant. At least moderate initial truncal valve stenosis and initial or residual regurgitation are independent risk factors associated with truncal valve intervention. Larger truncal valve root z-score is associated with significant truncal valve regurgitation and may identify a subset of patients at risk for truncal valve dysfunction over time.

Morphologic and histologic findings in bioprosthetic valves explanted from the mitral position in children younger than 5 years of age.

BACKGROUND: Mitral valve replacement (MVR) in very young children is challenging. This study investigates the mechanisms for early bioprosthetic valve failure in very young patients through review of the macroscopic and microscopic findings in explanted bioprosthetic valves. METHODS: Patients who underwent MVR with a bioprosthetic valve at Boston Children's Hospital between January 2010 to April 2016 at <5 years of age were the subjects of this study. Valve failure was defined as prosthetic mitral valve explantation with mitral valve re-replacement. RESULTS: Bioprosthetic valves were used in 31 of 77 MVRs during the study period. Valve failure occurred in 10 patients (32%). Freedom from valve failure was 80% at 1 year and was associated with older age at implantation. On gross and microscopic evaluation, valve failure (predominantly stenosis) was found to be due to pannus deposition and intrinsic leaflet calcification. CONCLUSIONS: Successful long-term use of bioprosthetic valves in the mitral position in very young children continues to be a challenge. In addition to intrinsic calcification, excessive pannus deposition can lead to early bioprosthetic valve failure in this population. Early exuberant pannus growth appears due to thrombus deposition on the valves themselves and to the host's reaction to foreign material.

The boundaries of fetal cardiac intervention: Expand or tighten?

Fetal cardiac intervention (FCI) is a relatively new and continually evolving field, and, for select cardiac defects, offers the potential to alter the progression of the disease and improve outcomes. It is a procedure that requires a collaborative effort between maternal-fetal medicine, interventional cardiology and fetal echo/ultrasound specialists, as well as fetal and maternal anesthesiologists, nursing specialists, and social workers. This article reviews the most recently reported data and advances in FCI. Currently, FCI is most frequently performed in fetuses with severe aortic stenosis (AS) with evolving hypoplastic left heart syndrome (eHLHS), established HLHS with intact or highly restrictive atrial septum (IAS), and pulmonary atresia with intact ventricular septum (PA-IVS) with evolving hypoplastic right heart syndrome (eHRHS). The goal of FCI for eHLHS and eHRHS is to promote a postnatal biventricular circulation with, theoretically, the potential for better long-term outcomes. In HLHS with IAS the aim is to improve survival. Contemporary data for FCI demonstrate limited maternal risks and improving technical success. With experience, FCI in severe AS with eHLHS has shown improved rates of biventricular outcome and early survival. Limited data for PA-IVS show promise for improving postnatal biventricular outcomes; however, for HLHS with IAS, FCI has yet to clearly demonstrate improved survival. FCI has an evolving role in the management of congenital heart defects. Ongoing analysis of disease progression, patient selection and postnatal outcomes, in conjuncture with technologic innovations and a multicenter collaborative approach, is essential as the field expands.