Surgically induced aortic coarctation in a neonatal porcine model allows for longitudinal assessment of cardiovascular changes.

Noncritical aortic coarctation (COA) typically presents beyond early childhood with hypertension. Correction of COA does not ensure a return to normal cardiovascular health, but the mechanisms are poorly understood. Therefore, we developed a porcine COA model to study the secondary cardiovascular changes. Eight male neonatal piglets (4 sham, 4 COA) underwent left posterolateral thoracotomy with descending aorta (DAO) mobilization. COA was created via a 1-cm longitudinal DAO incision with suture closure, plication, and placement and an 8-mm external band. All animals had cardiac catheterization at 6 (11-13 kg), 12 (26-31 kg), and 20 (67-70 kg) wk of age. Aortic luminal diameters were similar along the thoracic aorta, except for the COA region [6.4 mm COA vs. 17.3 mm sham at 20 wk (P < 0.001)]. Collateral flow could be seen as early as 6 wk. COA peak systolic pressure gradient was 20 mmHg at 6 wk and persisted through 20 wk increasing to 40 mmHg with dobutamine. Pulse pressures distal to the COA were diminished at 12 and 20 wk. This model addresses many limitations of prior COA models including neonatal creation at an expected anatomic position with intimal injury and vessel sizes similar to humans.NEW & NOTEWORTHY A neonatal model of aortic coarctation was developed in a porcine model using a readily reproducible method of aortic plication and external wrap placement. This model addresses the limitations of existing models including neonatal stenosis creation, appropriate anatomic location of the stenosis, and intimal injury creation and mimics human somatic growth. Pigs met American Heart Association (AHA) criteria for consideration of intervention, and the stenoses were graded as moderate to severe.

Non-invasive MRI Derived Hemodynamic Simulation to Predict Successful vs. Unsuccessful Catheter Interventions for Branch Pulmonary Artery Stenosis: Proof-of-Concept and Experimental Validation in Swine.

OBJECTIVE: This study assessed the ability of hemodynamic simulations to predict the success of catheter interventions in a swine model of branch pulmonary artery stenosis (bPAS). BACKGROUND: bPAS commonly occurs in congenital heart disease and is often managed with catheter based interventions. However, despite technical success, bPAS interventions do not lead to improved distal pulmonary blood flow (PBF) distribution in approximately 1/3rd of patients. New tools are needed to better identify which patients with bPAS would most benefit from catheter interventions. METHODS: For 13 catheter intervention cases in swine with surgically created left PAS (LPAS), PA pressures from right heart catheterization (RHC) and PBF distributions from MRI were measured before and after catheter interventions. Hemodynamic simulations with a reduced order computational fluid dynamics (CFD) model were performed using non-invasive PBF measurements derived from MRI, and then correlated with changes in invasive measures of hemodynamics and PBF distributions before and after catheter intervention to relieve bPAS. RESULTS: Compared to experimentally measured changes in left PBF distribution, simulations had a small bias (3.4 ± 11.1%), moderate agreement (ICC = 0.69 [0.24-0.90], 0.71 [0.23-0.91]), and good diagnostic capability to predict successful interventions (> 20% PBF increase) (AUC 0.83 [0.59-1.0]). Simulations had poorer prediction of changes in stenotic pressure gradient (ICC = 0.28 [- 0.33 to 0.73], r = 0.57 [- 0.04 to 0.87]) and MPA systolic pressure (ICC = 0.00 [- 0.52 to 0.53], r = 0.29 [- 0.32 to 0.72]). CONCLUSION: While there was only weak to moderate agreement between predicted and measured changes in PA pressures and pulmonary blood flow distributions, hemodynamic simulations did show good diagnostic value for predicting successful versus unsuccessful catheter based interventions to relieve bPAS. The results of this proof of concept study are promising and should encourage future development for using hemodynamic models in planning interventions for patients with bPAS.

Accelerated Estimation of Pulmonary Artery Stenosis Pressure Gradients with Distributed Lumped Parameter Modeling vs. 3D CFD with Instantaneous Adaptive Mesh Refinement: Experimental Validation in Swine.

Branch pulmonary artery stenosis (PAS) commonly occurs in congenital heart disease and the pressure gradient over a stenotic PA lesion is an important marker for re-intervention. Image based computational fluid dynamics (CFD) has shown promise for non-invasively estimating pressure gradients but one limitation of CFD is long simulation times. The goal of this study was to compare accelerated predictions of PAS pressure gradients from 3D CFD with instantaneous adaptive mesh refinement (AMR) versus a recently developed 0D distributed lumped parameter CFD model. Predictions were then experimentally validated using a swine PAS model (n = 13). 3D CFD simulations with AMR improved efficiency by 5 times compared to fixed grid CFD simulations. 0D simulations further improved efficiency by 6 times compared to the 3D simulations with AMR. Both 0D and 3D simulations underestimated the pressure gradients measured by catheterization (- 1.87 ± 4.20 and - 1.78 ± 3.70 mmHg respectively). This was partially due to simulations neglecting the effects of a catheter in the stenosis. There was good agreement between 0D and 3D simulations (ICC 0.88 [0.66-0.96]) but only moderate agreement between simulations and experimental measurements (0D ICC 0.60 [0.11-0.86] and 3D ICC 0.66 [0.21-0.88]). Uncertainty assessment indicates that this was likely due to limited medical imaging resolution causing uncertainty in the segmented stenosis diameter in addition to uncertainty in the outlet resistances. This study showed that 0D lumped parameter models and 3D CFD with instantaneous AMR both improve the efficiency of hemodynamic modeling, but uncertainty from medical imaging resolution will limit the accuracy of pressure gradient estimations.

Stent interventions for pulmonary artery stenosis improve bi-ventricular flow efficiency in a swine model.

BACKGROUND: Branch pulmonary artery (PA) stenosis (PAS) commonly occurs in patients with congenital heart disease (CHD). Prior studies have documented technical success and clinical outcomes of PA stent interventions for PAS but the impact of PA stent interventions on ventricular function is unknown. The objective of this study was to utilize 4D flow cardiovascular magnetic resonance (CMR) to better understand the impact of PAS and PA stenting on ventricular contraction and ventricular flow in a swine model of unilateral branch PA stenosis. METHODS: 18 swine (4 sham, 4 untreated left PAS, 10 PAS stent intervention) underwent right heart catheterization and CMR at 20 weeks age (55 kg). CMR included ventricular strain analysis and 4D flow CMR. RESULTS: 4D flow CMR measured inefficient right ventricular (RV) and left ventricular (LV) flow patterns in the PAS group (RV non-dimensional (n.d.) vorticity: sham 82 ± 47, PAS 120 ± 47; LV n.d. vorticity: sham 57 ± 5, PAS 78 ± 15 p < 0.01) despite the PAS group having normal heart rate, ejection fraction and end-diastolic volume. The intervention group demonstrated increased ejection fraction that resulted in more efficient ventricular flow compared to untreated PAS (RV n.d. vorticity: 59 ± 12 p < 0.01; LV n.d. vorticity: 41 ± 7 p < 0.001). CONCLUSION: These results describe previously unknown consequences of PAS on ventricular function in an animal model of unilateral PA stenosis and show that PA stent interventions improve ventricular flow efficiency. This study also highlights the sensitivity of 4D flow CMR biomarkers to detect earlier ventricular dysfunction assisting in identification of patients who may benefit from PAS interventions.

Longitudinal Evolution of Pulmonary Artery Wall Shear Stress in a Swine Model of Pulmonary Artery Stenosis and Stent Interventions.

Branch pulmonary artery stenosis (PAS) commonly occurs in congenital heart disease and it has previously been hypothesized that in branch PAS the pulmonary arteries (PAs) remodel their lumen diameter to maintain constant wall shear stress (WSS). We quantified the longitudinal progression of PA WSS in a swine model of unilateral PAS and two different intervention time courses to test this hypothesis. To quantify WSS in the entire pulmonary tree we used 4D Flow MRI for the large-proximal PAs and a structured tree model for the small-distal PAs. Our results only partially supported the hypothesis that in branch PAS the PAs remodel their lumen diameter to maintain WSS homeostasis. Proximal PA WSS was similar between groups at the final study time-point but WSS of mid-sized (5 mm to 500 µm) PA segments was found to be different between the sham and LPAS groups. This suggests that WSS homeostasis may only be achieved for the large-proximal PAs. Additionally, our results do not show WSS homeostasis being achieved over shorter periods of time suggesting that any potential WSS dependent changes in PA lumen diameter were a long-term remodeling response rather than a short-term vasodilation response. Future studies should confirm if these findings hold true in humans and investigate the impacts of WSS at different levels of the pulmonary tree on growth.

Comparison of pulmonary artery dimensions in swine obtained from catheter angiography, multi-slice computed tomography, 3D-rotational angiography and phase-contrast magnetic resonance angiography.

Accurate pulmonary artery (PA) imaging is necessary for management of patients with complex congenital heart disease (CHD). The ability of newer imaging modalities such as 3D rotational angiography (3DRA) or phase-contrast magnetic resonance angiography (PC-MRA) to measure PA diameters has not been compared to established angiography techniques. Measurements of PA diameters (including PA stenosis and PA stents) from 3DRA and non-contrast-enhanced PC-MRA were compared to 2D catheter angiography (CA) and multi-slice computed tomography (MSCT) in a swine CHD model (n = 18). For all PA segments 3DRA had excellent agreement with CA and MSCT (ICC = 0.94[0.91-0.95] and 0.92[0.89-0.94]). 3DRA PA stenosis measures were similar to CA and MSCT and 3DRA was on average within 5% of 10.8 ± 1.3 mm PA stent diameters from CA and MSCT. For compliant PA segments, 3DRA was on average 3-12% less than CA (p < 0.05) and MSCT (p < 0.01) for 6-14 mm vessels. PC-MRA could not reliably visualize stents and distal PA vessels and only identified 34% of all assigned measurement sites. For measured PA segments, PC-MRA had good agreement to CA and MSCT (ICC = 0.87[0.77-0.92] and 0.83[0.72-0.90]) but PC-MRA overestimated stenosis diameters and underestimated compliant PA diameters. Excellent CA-MSCT PA diameter agreement (ICC = 0.95[0.93-0.96]) confirmed previous data in CHD patients. There was little bias in PA measurements between 3DRA, CA and MSCT in stenotic and stented PAs but 3DRA underestimates measurements of compliant PA regions. Accurate PC-MRA imaging was limited to unstented proximal PA anatomy.

Pulmonary artery and lung parenchymal growth following early versus delayed stent interventions in a swine pulmonary artery stenosis model.

OBJECTIVES: Compare lung parenchymal and pulmonary artery (PA) growth and hemodynamics following early and delayed PA stent interventions for treatment of unilateral branch PA stenosis (PAS) in swine. BACKGROUND: How the pulmonary circulation remodels in response to different durations of hypoperfusion and how much growth and function can be recovered with catheter directed interventions at differing time periods of lung development is not understood. METHODS: A total of 18 swine were assigned to four groups: Sham (n = 4), untreated left PAS (LPAS) (n = 4), early intervention (EI) (n = 5), and delayed intervention (DI) (n = 5). EI had left pulmonary artery (LPA) stenting at 5 weeks (6 kg) with redilation at 10 weeks. DI had stenting at 10 weeks. All underwent right heart catheterization, computed tomography, magnetic resonance imaging, and histology at 20 weeks (55 kg). RESULTS: EI decreased the extent of histologic changes in the left lung as DI had marked alveolar septal and bronchovascular abnormalities (p = .05 and p < .05 vs. sham) that were less prevalent in EI. EI also increased left lung volumes and alveolar counts compared to DI. EI and DI equally restored LPA pulsatility, R heart pressures, and distal LPA growth. EI and DI improved, but did not normalize LPA stenosis diameter (LPA/DAo ratio: Sham 1.27 ± 0.11 mm/mm, DI 0.88 ± 0.10 mm/mm, EI 1.01 ± 0.09 mm/mm) and pulmonary blood flow distributions (LPA-flow%: Sham 52 ± 5%, LPAS 7 ± 2%, DI 44 ± 3%, EI 40 ± 2%). CONCLUSION: In this surgically created PAS model, EI was associated with improved lung parenchymal development compared to DI. Longer durations of L lung hypoperfusion did not detrimentally affect PA growth and R heart hemodynamics. Functional and anatomical discrepancies persist despite successful stent interventions that warrant additional investigation.

Technical Performance Score Predicts Perioperative Outcomes in Complex Congenital Heart Surgery Performed in a Small-to-Medium-Volume Program.

As the quality of surgical outcomes depend on many factors, the development of validated tools to assess the different aspects of complex multidisciplinary teams' performance is crucial. The Technical Performance Score (TPS) has only been validated to correlate with outcomes in large-volume surgical programs. Here we assess the utility of TPS in correlation to perioperative outcomes for complex congenital heart surgeries (CHS) performed in a small-to-medium-volume program. 673 patients underwent CHS from 4/2012 to 12/2017 at our institution. Of those, 122 were STAT 4 and STAT 5. TPS was determined for each STAT 4 and STAT 5 operation using discharge echocardiogram: 1 = optimal, 2 = adequate, 3 = inadequate. Patient outcomes were compared including mortality, length of stay, ventilation times, and adverse events. 69 patients (57%) were neonates, 32 (26%) were infants, 17 (14%) were children, 4 (3%) were adults. TPS class 1 was assigned to 85 (70%) operations, TPS class 2 was assigned to 25 (20%) operations, and TPS class 3 was assigned to 12 (10%) operations. TPS was associated with re-intubation, ICU length of stay, postoperative length of stay, and mortality. TPS did not correlate with unplanned 30-day readmissions, need for reoperation, and inotropic score. Technical performance score was associated with perioperative outcomes and is a useful tool to assess the adequacy of repair for high complexity CHS in a small-to-medium-volume surgical program. TPS should be a part of program review in congenital heart programs of all sizes to identify strategies that may reduce postoperative morbidity and potentially improve long-term outcomes.

Mid-Term Valve-Related Outcomes After Transcatheter Tricuspid Valve-in-Valve or Valve-in-Ring Replacement.

BACKGROUND: Transcatheter aortic and pulmonary valves have been used to treat stenosis or regurgitation after prior surgical tricuspid valve (TV) replacement or repair. Little is known about intermediate-term valve-related outcomes after transcatheter tricuspid valve replacement (TTVR), including valve function, thrombus, and endocarditis. OBJECTIVES: The authors sought to evaluate mid-term outcomes in a large cohort of patients who underwent TTVR after surgical TV repair or replacement, with a focus on valve-related outcomes. METHODS: Patients who underwent TTVR after prior surgical TV replacement or repair were collected through an international registry. Time-related outcomes were modeled and risk factors assessed. RESULTS: Data were collected for 306 patients who underwent TTVR from 2008 through 2017 at 80 centers; 52 patients (17%) had a prior history of endocarditis. Patients were followed for a median of 15.9 months after implantation (0.1 to 90 months), with 64% of patients estimated to be alive without TV reintervention or a valve-related event at 3 years. The cumulative 3-year incidence of death, reintervention, and valve-related adverse outcomes (endocarditis, thrombosis, or significant dysfunction) were 17%, 12%, and 8%, respectively. Endocarditis was diagnosed in 8 patients 2 to 29 months after TTVR, for an annualized incidence rate of 1.5% per patient-year (95% confidence interval: 0.45% to 2.5%). An additional 8 patients were diagnosed with clinically relevant valve thrombosis, 3 in the short term, 2 within 2 months, and 3 beyond 6 months. Only 2 of these 8 patients received anticoagulant therapy before thrombus detection (p = 0.13 vs. patients without thrombus). Prior endocarditis was not a risk factor for reintervention, endocarditis, or valve thrombosis, and there was no difference in valve-related outcomes according to TTVR valve type. CONCLUSIONS: TV dysfunction, endocarditis, and leaflet thrombosis were uncommon after TTVR. Patients with prior endocarditis were not at higher risk for endocarditis or other adverse outcomes after TTVR, and endocarditis occurred with similar frequency in different valve types. Though rare, leaflet thrombosis is an important adverse outcome, and further study is necessary to determine the appropriate level of prophylactic therapy after TTVR.

Multicenter Assessment of Radiation Exposure during Pediatric Cardiac Catheterizations Using a Novel Imaging System.

OBJECTIVES: To quantify radiation exposure during pediatric cardiac catheterizations performed by multiple operators on a new imaging platform, the Artis Q.zen (Siemens Healthcare, Forchheim, Germany), and to compare these data to contemporary benchmark values. BACKGROUND: The Artis Q.zen has been shown to achieve significant radiation reduction during select types of pediatric cardiac catheterizations in small single-center studies. No large multicenter study exists quantifying patient dose exposure for a broad spectrum of procedures. METHODS: Retrospective collection of Air Kerma (AK) and dose area product (DAP) for all pediatric cardiac catheterizations performed on this new imaging platform at four institutions over a two-year time period. RESULTS: A total of 1,127 pediatric cardiac catheterizations were analyzed. Compared to dose data from earlier generation Artis Zee imaging systems, this study demonstrates 70-80% dose reduction (AK and DAP) for similar patient and procedure types. Compared to contemporary benchmark data for common interventional procedures, this study demonstrates an average percent reduction in AK and DAP from the lowest dose saving per intervention of 39% for AK and 27% for DAP for transcatheter pulmonary valve implantation up to 77% reduction in AK and 70% reduction in DAP for atrial septal defect closure. CONCLUSION: Use of next-generation imaging platforms for pediatric cardiac catheterizations can substantially decrease patient radiation exposure. This multicenter study defines new low-dose radiation measures achievable on a novel imaging system.

Early Pulmonary Vascular Disease in Young Adults Born Preterm.

Rationale: Premature birth affects 10% of live births in the United States and is associated with alveolar simplification and altered pulmonary microvascular development. However, little is known about the long-term impact prematurity has on the pulmonary vasculature.Objectives: Determine the long-term effects of prematurity on right ventricular and pulmonary vascular hemodynamics.Methods: Preterm subjects (n = 11) were recruited from the Newborn Lung Project, a prospectively followed cohort at the University of Wisconsin-Madison, born preterm with very low birth weight (≤1,500 g; average gestational age, 28 wk) between 1988 and 1991. Control subjects (n = 10) from the same birth years were recruited from the general population. All subjects had no known adult cardiopulmonary disease. Right heart catheterization was performed to assess right ventricular and pulmonary vascular hemodynamics at rest and during hypoxic and exercise stress.Measurements and Main Results: Preterm subjects had higher mean pulmonary arterial pressures (mPAPs), with 27% (3 of 11) meeting criteria for borderline pulmonary hypertension (mPAP, 19-24 mm Hg) and 18% (2 of 11) meeting criteria for overt pulmonary hypertension (mPAP ≥ 25 mm Hg). Pulmonary vascular resistance and elastance were higher at rest and during exercise, suggesting a stiffer vascular bed. Preterm subjects were significantly less able to augment cardiac index or right ventricular stroke work during exercise. Among neonatal characteristics, total ventilatory support days was the strongest predictor of adult pulmonary pressure.Conclusions: Young adults born preterm demonstrate early pulmonary vascular disease, characterized by elevated pulmonary pressures, a stiffer pulmonary vascular bed, and right ventricular dysfunction, consistent with an increased risk of developing pulmonary hypertension.

Inspiratory and expiratory resistance cause right-to-left bubble passage through the foramen ovale.

A patent foramen ovale (PFO) is linked to increased risk of decompression illness in divers. One theory is that venous gas emboli crossing the PFO can be minimized by avoiding lifting, straining and Valsalva maneuvers. Alternatively, we hypothesized that mild increases in external inspiratory and expiratory resistance, similar to that provided by a SCUBA regulator, recruit the PFO. Nine healthy adults with a Valsalva-proven PFO completed three randomized trials (inspiratory, expiratory, and combined external loading) with six levels of increasing external resistance (2-20 cmH2 O/L/sec). An agitated saline contrast echocardiogram was performed at each level to determine foramen ovale patency. Contrary to our hypothesis, there was no relationship between the number of subjects recruiting their PFO and the level of external resistance. In fact, at least 50% of participants recruited their PFO during 14 of 18 trials and there was no difference between the combined inspiratory, expiratory, or combined external resistance trials (P > 0.05). We further examined the relationship between PFO recruitment and intrathoracic pressure, estimated from esophageal pressure. Esophageal pressure was not different between participants with and without a recruited PFO. Intrasubject variability was the most important predictor of PFO patency, suggesting that some individuals are more likely to recruit their PFO in the face of even mild external resistance. Right-to-left bubble passage through the PFO occurs in conditions that are physiologically relevant to divers. Transthoracic echocardiography with mild external breathing resistance may be a tool to identify divers that are at risk of PFO-related decompression illness.

Branch Pulmonary Artery Valve Implantation Reduces Pulmonary Regurgitation and Improves Right Ventricular Size/Function in Patients With Large Right Ventricular Outflow Tracts.

OBJECTIVES: The authors sought to assess the intermediate-term effects of percutaneous placed valves in the branch pulmonary artery (PA) position. BACKGROUND: Most patients with large right ventricular outflow tracts (RVOTs) are excluded from available percutaneous pulmonary valve options. In some of these patients, percutaneous branch PA valve implantation may be feasible. The longer-term effects of valves in the branch PA position is unknown. METHODS: Retrospective data were collected on patients with significant pulmonary regurgitation who had a percutaneous branch PA valve attempted. RESULTS: Percutaneous branch PA valve implantation was attempted in 34 patients (18 bilateral and 16 unilateral). One-half of the patients were in New York Heart Association (NHYA) functional class III or IV pre-implantation. There were 2 failed attempts and 6 procedural complications. At follow-up, only 1 patient had more than mild valvar regurgitation. The right ventricular end-diastolic volume index decreased from 147 (range: 103 to 478) ml/m2 to 101 (range: 76 to 429) ml/m2, p < 0.01 (n = 16), and the right ventricular end-systolic volume index decreased from 88.5 (range: 41 to 387) ml/m2 to 55.5 (range: 40.2 to 347) ml/m2, p < 0.01 (n = 13). There were 5 late deaths. At a median follow-up of 2 years, all other patients were in NYHA functional class I or II. CONCLUSIONS: Percutaneous branch PA valve implantation results in a reduction in right ventricular volume with clinical benefit in the intermediate term. Until percutaneous valve technology for large RVOTs is refined and more widely available, branch PA valve implantation remains an option for select patients.

Consequences of an early catheter-based intervention on pulmonary artery growth and right ventricular myocardial function in a pig model of pulmonary artery stenosis.

OBJECTIVE: To determine the consequences of an early catheter-based intervention on pulmonary artery (PA) growth and right ventricular (RV) myocardial function in an animal model of branch PA stenosis. BACKGROUND: Acute results and safety profiles of deliberate stent fracture within the pulmonary vasculature have been demonstrated. The long-term impact of early stent intervention and deliberate stent fracture on PA growth and myocardial function is not understood. METHODS: Implantation of small diameter stents was performed in a pig model of left PA stenosis at 6 weeks (10 kg) followed by dilations at 10 (35 kg) and 18 weeks (65 kg) with intent to fracture and implant large diameter stents. Hemodynamics, RV contractility, and 2D/3D angiography were performed with each intervention. The heart and pulmonary vasculature were histologically assessed. RESULTS: Stent fracture occurred in 9/12 and implantation of large diameter stents was successful in 10/12 animals with no PA aneurysms or dissections. The final stented PA segment and distal left PA branch origins equaled the corresponding PA diameters of sham controls. Growth of left PA immediately beyond the stent was limited and there was diffuse fibro-intimal proliferation within the distal left and right PA. RV contractility was diminished in the intervention group and the response to dobutamine occurred uniquely via increases in heart rate. CONCLUSIONS: Early stent intervention in this surgically created PA stenosis model was associated with improved growth of the distal PA vasculature but additional investigation of PA vessel physiology and impact on the developing heart are needed.

Intraoperative Completion Angiogram May Be Superior to Transesophageal Echocardiogram for Detection of Pulmonary Artery Residual Lesions in Congenital Heart Surgery.

The purpose of this study was to assess the diagnostic capabilities of transesophageal echocardiography (TEE) compared to completion angiography for detection of residual post-operative pulmonary artery lesions. This is a retrospective review of 19 consecutive surgical cases involving the pulmonary arteries that had post-operative TEE and completion angiography from 2014 to 2017. The echocardiograms were reviewed by 2 blinded examiners and categorized as adequate or inadequate visualization of the surgical repair. Based on TEE images, the surgical repair was graded as no revision necessary, residual lesion present requiring revision, or unable to assess. TEE was compared to completion angiography to determine the ability of each method to detect residual pulmonary artery lesions. Fifty-three percent of TEE imaging was graded as inadequate. Based on TEE, surgical revision was indicated in 2 of 19 cases. Completion angiography documented 4 additional residual lesions resulting in surgical revision in 6 of 19 patients. TEE sensitivity for detecting residual pulmonary artery lesions was 40%. One Glenn patient with adequate image quality and repair by TEE had moderate left pulmonary artery stenosis by completion angiography. All other discrepancies occurred in patients with inadequate TEE imaging. No patient with pulmonary artery abnormalities had hemodynamic instability or excessive desaturations. Completion angiography-related complications included three transient arrhythmias with no increased incidence of acute kidney injury. Completion angiography may be more effective than TEE at detecting post-operative pulmonary artery lesions even in patients not manifesting clinical symptoms. Documentation of residual lesions with completion angiography allows immediate surgical revision potentially limiting necessity for future interventions.

Radiation Reduction Capabilities of a Next-Generation Pediatric Imaging Platform.

The aims of this study were to quantify patient radiation exposure for a single interventional procedure during transition from an adult catheterization laboratory to a next-generation imaging system with pediatric settings, and to compare this radiation data to published benchmarks. Radiation exposure occurs with any X-ray-directed pediatric catheterization. Technologies and imaging techniques that limit dose while preserving image quality benefit patient care. Patient radiation dose metrics, air kerma, and dose-area product (DAP) were retrospectively obtained for patients <20 kg who underwent patent ductus arteriosus (PDA) closure on a standard imaging system (Group 1, n = 11) and a next-generation pediatric imaging system (Group 2, n = 10) with air-gap technique. Group 2 radiation dose metrics were then compared to published benchmarks. Patient demographics, procedural technique, PDA dimensions, closure devices, and fluoroscopy time were similar for the two groups. Air kerma and DAP decreased by 65-70% in Group 2 (p values <0.001). The average number of angiograms approached statistical significance (p value = 0.06); therefore, analysis of covariance (ANCOVA) was conducted that confirmed significantly lower dose measures in Group 2. This degree of dose reduction was similar when Group 2 data (Kerma 28 mGy, DAP 199 µGy m(2)) was compared to published benchmarks for PDA closure (Kerma 76 mGy, DAP 500 µGy m(2)). This is the first clinical study documenting the radiation reduction capabilities of a next-generation pediatric imaging platform. The true benefit of this dose reduction will be seen in patients requiring complex and often recurrent catheterizations.

Decreased incidence of right-ventricular outflow tract complications using a retrograde snare technique for radiofrequency pulmonary valve perforation.

Perforation of the atretic pulmonary valve with balloon dilation in infants with pulmonary atresia with intact ventricular septum (PA-IVS) is standard initial therapy for right-ventricular (RV) decompression. This procedure often results in adequate pulmonary blood flow, thus eliminating the need for neonatal surgery. Nonetheless, the incidence of RV outflow-tract complications and mortality for this intervention is significant. We report our experience with retrograde snare-guided radiofrequency (RF) perforation in an attempt to improve accuracy and decrease procedural complications. Medical records were reviewed for the period between March 2007 and May 2010 for all patients with PA-IVS who presented to the catheterization laboratory for attempted RF perforation in infancy. Specific details reviewed included demographics, preprocedural echocardiographic (echo) data, procedural technique and complications, pre- and post-RV pressures and pulmonary valve gradients, need for surgical intervention in the neonatal period, and short- to medium-term follow-up. Eleven neonates with PA-IVS underwent RF perforation using a retrograde snare-guided technique during the study period. The pulmonary valve was successfully perforated and the wire snared in all 11 patients. Six of 11 atretic valves were crossed on the first attempt with low energy (5 W × 2 s). No episodes of tamponade or RV/PA perforation occurred as confirmed by echocardiogram performed immediately after the procedure. There was no ductal spasm with retrograde catheter manipulations. Sequential dilation of the perforated valve was not necessary. RV pressures decreased from 169 % systemic before dilation to 93 % after dilation (p < 0.001) with a residual pulmonary valve gradient of 16 ± 6 mm Hg. Eight of 11 patients (73 %) were discharged without surgery at an average 16 days after the intervention. Three patients required Blalock-Taussig shunts to augment pulmonary blood flow. Femoral artery thrombus occurred in 4 of 11 patients treated with anticoagulation, and 2 patients had atrial arrhythmias during the procedure. No other complications occurred. No preprocedural echo parameters predicted requirement for surgical shunt before hospital discharge. Retrograde snare-guided pulmonary valve perforation in infants with PA-IVS is safe and may decrease the incidence of significant procedural complications.

Coarctectomy combined with an interdigitating arch reconstruction results in a lower incidence of recurrent arch obstruction after the Norwood procedure than coarctectomy alone.

OBJECTIVE: Recurrent aortic arch obstruction after the Norwood procedure continues to be a source of morbidity. We sought to determine if a modified interdigitating technique for aortic arch reconstruction during the Norwood procedure decreased recurrent arch obstruction. METHODS: A total of 142 consecutive infants undergoing the Norwood procedure were divided into groups according to surgical technique: Group 1 (n = 79, January 1999 to May 2003) underwent arch reconstruction with complete coarctectomy followed by anastomosis of the descending aorta to the transverse arch. Group 2 (n = 63, June 2003 to September 2006) underwent complete coarctectomy plus a modified interdigitating technique. Catheterization before stage 2 palliation was reviewed for hemodynamics and angiographic arch dimensions, and a coarctation index was calculated. RESULTS: Reintervention for recurrent coarctation occurred in 28% (22/79) of group 1 patients compared with 2% (1/63) of group 2 patients (P = .001). Aortic pressures, gradients, dimensions, and coarctation index were consistently more favorable for group 2. CONCLUSIONS: Coarctectomy plus an interdigitating arch anastomosis was superior to coarctectomy alone and resulted in a dramatically decreased incidence of recurrent arch obstruction.

Mixed venous oxygen saturation monitoring after stage 1 palliation for hypoplastic left heart syndrome.

BACKGROUND: Staged palliation for hypoplastic left heart syndrome has been marked by high early mortality due to the limited cardiac output of the postischemic single right ventricle combined with the inefficiency and volatility of parallel circulation. METHODS: Since July 1996, we have performed stage 1 palliation (S1P) in 178 patients. Within this group is a consecutive cohort of 116 patients with true hypoplastic left heart syndrome that underwent S1P with a modified Blalock-Taussig shunt. A prospective database containing postoperative hemodynamic data was maintained on all patients. Studied were the incidence of organ failure, extracorporeal membrane oxygenation (ECMO), and mortality, as well as the relationship between these outcomes and postoperative hemodynamics. RESULTS: Hospital survival for this cohort was 93% (108/116). Patients who died after S1P had a lower superior vena cava oxygen saturation (SVO2) level compared with survivors (53.1% +/-10.6% versus 59.3% +/-9.2%, p = 0.034). Renal failure developed in 2 (1.7%) of the 116 patients, necrotizing enterocolitis developed in 1 (0.9%), and 5 (4.3%) had clinical seizures. ECMO support was instituted in 12 patients (10.3%). The SVO2 level was lower in patients requiring ECMO (54.0% +/- 9.7% versus 59.9% +/- 9.2%, p = 0.031). CONCLUSIONS: Goal-directed therapy with SVO2 as an indicator of systemic oxygen delivery is associated with excellent early survival and a low incidence of organ failure after S1P. Inability to optimize SVO2 in the early postoperative period is associated with an increased risk of organ failure, ECMO, and death.