Thoracic duct drainage patterns in heterotaxy.

BACKGROUND: Disordered lymphatic drainage is common in congenital heart diseases (CHD), but thoracic duct (TD) drainage patterns in heterotaxy have not been described in detail. This study sought to describe terminal TD sidedness in heterotaxy and its associations with other anatomic variables. METHODS: This was a retrospective, single-center study of patients with heterotaxy who underwent cardiovascular magnetic resonance imaging at a single center between July 1, 2019 and May 15, 2023. Patients with (1) asplenia (right isomerism), (2) polysplenia (left isomerism) and (3) pulmonary/abdominal situs inversus (PASI) plus CHD were included. Terminal TD sidedness was described as left-sided, right-sided, or bilateral. RESULTS: Of 115 eligible patients, the terminal TD was visualized in 56 (49 %). The terminal TD was left-sided in 25 patients, right-sided in 29, and bilateral in two. On univariate analysis, terminal TD sidedness was associated with atrial situs (p = 0.006), abdominal situs (p = 0.042), type of heterotaxy (p = 0.036), the presence of pulmonary obstruction (p = 0.041), superior vena cava sidedness (p = 0.005), and arch sidedness (p < 0.001). On multivariable analysis, only superior vena cava and aortic arch sidedness were independently associated with terminal TD sidedness. CONCLUSIONS: Terminal TD sidedness is highly variable in patients with heterotaxy. Superior vena cava and arch sidedness are independently associated with terminal TD sidedness. Type of heterotaxy was not independently associated with terminal TD sidedness. This data improves the understanding of anatomic variation in patients with heterotaxy and may be useful for planning for lymphatic interventions.

Hybrid Left Heart Bypass Circuit for Repair of the Descending Aorta in an 8-kg Williams Syndrome Patient.

A 1-year old male patient with Williams syndrome and multiple prior interventions presented for surgical repair of his descending aorta (DA) through a left thoracotomy. Concerns for significant bleeding and spinal cord protection led the care team to consider a left heart bypass (LHB) circuit with options for pump sucker use, heat exchange capacity, and the possibility of converting to traditional cardiopulmonary bypass (CPB). A traditional CPB circuit with a roller-head arterial pump was assembled with a bypass line around the cardiotomy venous reservoir (CVR). Excluding the CVR with this line allowed for a closed LHB circuit. A second pump head was integrated to both recirculate the CVR volume and to serve as a means for controlled volume administration to the closed LHB circuit. Pump sucker return directed to the CVR could easily be transfused back to the patient. The patient was placed on the hybrid LHB circuit and cooled to 32°C. DA clamps were placed. Upper body dynamic blood pressure was managed for a target mean of 50 mmHg, the left atrial pressure (LAP) was maintained in the 5-7 mmHg range, and the nonpulsatile lower body blood pressure was targeted at 40-50 mmHg. Cerebral near-infrared spectroscopy (NIRS) helped guide volume and pressure management. The surgeons placed two long-segment patches on the DA, moving clamps as needed. The patient was rewarmed and separated from the hybrid LHB circuit after 82 minutes. Closed circuit LHB can be provided with a roller-head hybrid circuit incorporating an oxygenator for gas exchange, central cooling and warming, and arterial line filtration along with a CVR for pump sucker use and controlled transfusion to the patient.

A Multi-Mode System for Myocardial Functional and Physiological Assessment during Ex Situ Heart Perfusion.

Ex situ heart perfusion (ESHP) has proven to be an important and valuable step toward better preservation of donor hearts for heart transplantation. Currently, few ESHP systems allow for a convenient functional and physiological evaluation of the heart. We sought to establish a simple system that provides functional and physiological assessment of the heart during ESHP. The ESHP circuit consists of an oxygenator, a heart-lung machine, a heater-cooler unit, an anesthesia gas blender, and a collection funnel. Female Yorkshire pig hearts (n = 10) had del Nido cardioplegia (4°C) administered, excised, and attached to the perfusion system. Hearts were perfused retrogradely into the aortic root for 2 hours before converting the system to an isovolumic mode or a working mode for further 2 hours. Blood samples were analyzed to measure metabolic parameters. During the isovolumic mode (n = 5), a balloon inserted in the left ventricular (LV) cavity was inflated so that an end-diastolic pressure of 6-8 mmHg was reached. During the working mode (n = 5), perfusion in the aortic root was redirected into left atrium (LA) using a compliance chamber which maintained an LA pressure of 6-8 mmHg. Another compliance chamber was used to provide an afterload of 40-50 mmHg. Hemodynamic and metabolic conditions remained stable and consistent for a period of 4 hours of ESHP in both isovolumic mode (LV developed pressure: 101.0 ± 3.5 vs. 99.7 ± 6.8 mmHg, p = .979, at 2 and 4 hours, respectively) and working mode (LV developed pressure: 91.0 ± 2.6 vs. 90.7 ± 2.5 mmHg, p = .942, at 2 and 4 hours, respectively). The present study proposed a novel ESHP system that enables comprehensive functional and metabolic assessment of large mammalian hearts. This system allowed for stable myocardial function for up to 4 hours of perfusion, which would offer great potential for the development of translational therapeutic protocols to improve dysfunctional donated hearts.

Physiologic effects of delayed sternal closure following stage 1 palliation.

BACKGROUND: Following stage 1 palliation, delayed sternal closure may be used as a technique to enhance thoracic compliance but may also prolong the length of stay and increase the risk of infection. METHODS: We reviewed all neonates undergoing stage 1 palliation at our institution between 2010 and 2017 to describe the effects of delayed sternal closure. RESULTS: During the study period, 193 patients underwent stage 1 palliation, of whom 12 died before an attempt at sternal closure. Among the 25 patients who underwent primary sternal closure, 4 (16%) had sternal reopening within 24 hours. Among the 156 infants who underwent delayed sternal closure at 4 [3,6] days post-operatively, 11 (7.1%) had one or more failed attempts at sternal closure. Patients undergoing primary sternal closure had a shorter duration of mechanical ventilation and intensive care unit length of stay. Patients who failed delayed sternal closure had a longer aortic cross-clamp time (123±42 versus 99±35 minutes, p=0.029) and circulatory arrest time (39±28 versus 19±17 minutes, p=0.0009) than those who did not fail. Failure of delayed sternal closure was also closely associated with Technical Performance Score: 1.3% of patients with a score of 1 failed sternal closure compared with 18.9% of patients with a score of 3 (p=0.0028). Among the haemodynamic and ventilatory parameters studied, only superior caval vein saturation following sternal closure was different between patients who did and did not fail sternal closure (30±7 versus 42±10%, p=0.002). All patients who failed sternal closure did so within 24 hours owing to hypoxaemia, hypercarbia, or haemodynamic impairment. CONCLUSION: When performed according to our current clinical practice, sternal closure causes transient and mild changes in haemodynamic and ventilatory parameters. Monitoring of SvO2 following sternal closure may permit early identification of patients at risk for failure.

Comparison of two pediatric cases requiring the use of bivalirudin during cardiopulmonary bypass.

INTRODUCTION: Comparison of two pediatric cases at our institution that utilized bivalirudin for anticoagulation on cardiopulmonary bypass (CPB); a bilateral lung transplant (BLT) and a ventricular assist device (VAD) implantation. METHODS: The same bivalirudin protocol was utilized in both cases with an initial bolus of 1 mg/kg administered by the anesthesia team, a 50 mg bolus in the pump prime at the time of the initial patient bolus and an initial infusion rate of 2.5 mg/kg/h, with titration as needed during CPB to maintain kaolin-activated clotting time (K-ACT) values >400 s. RESULTS: The BLT experienced high K-ACT levels (>720 s) for the majority of the case despite decreasing the bivalirudin infusion rate to 0.5 mg/kg/h. The VAD implantation case required the bivalirudin infusion rate to be increased to 5.0 mg/kg/h throughout the case due to low K-ACTs. CONCLUSION: The literature strongly supports a specific infusion rate1-7 (2.5 mg/kg/h) for bivalirudin anticoagulation during extracorporeal circulation. Clinicians must consider the loss of clotting factors and the administration of blood products while adjusting the bivalirudin infusion during bypass. We have now elected to maintain an infusion rate of ≥0.5 mg/kg/h for bivalirudin anticoagulation at our center, based on institutional experience, though consideration for a higher infusion rate for an added margin of safety should be considered. It is imperative to have a well-developed protocol for the management of these cardiopulmonary bypass patients and we offer our one-page timeline of events to help guide other pediatric centers looking to use bivalirudin anticoagulation.

Rapid isolation of bone marrow mesenchymal stromal cells using integrated centrifuge-based technology.

BACKGROUND AIMS: The use of bone marrow-derived mesenchymal stromal cells (MSCs) in cell-based therapies is currently being developed for a number of diseases. Thus far, the clinical results have been inconclusive and variable, in part because of the variety of cell isolation procedures and culture conditions used in each study. A new isolation technique that streamlines the method of concentration and demands less time and attention could provide clinical and economic advantages compared with current methodologies. In this study, we evaluated the concentrating capability of an integrated centrifuge-based technology compared with standard Ficoll isolation. METHODS: MSCs were concentrated from bone marrow aspirate using the new device and the Ficoll method. The isolation capabilities of the device and the growth characteristics, secretome production, and differentiation capacity of the derived cells were determined. RESULTS: The new MSC isolation device concentrated the bone marrow in 90 seconds and resulted in a mononuclear cell yield 10-fold higher and with a twofold increase in cell retention compared with Ficoll. The cells isolated using the device were shown to exhibit similar morphology and functional activity as assessed by growth curves and secretome production compared to the Ficoll-isolated cells. The surface marker and trilineage differentiation profile of the device-isolated cells was consistent with the known profile of MSCs. DISCUSSION: The faster time to isolation and greater cell yield of the integrated centrifuge-based technology may make this an improved approach for MSC isolation from bone marrow aspirates.

Recommendations for utilization of the paracorporeal lung assist device in neonates and young children with pulmonary hypertension.

The management of decompensating critically ill children with severe PH is extremely challenging and requires a multidisciplinary approach. Unfortunately, even with optimal care, these children might continue to deteriorate and develop inadequate systemic perfusion and at times cardiac arrest secondary to a pulmonary hypertensive crisis. Tools to support these children are limited, and at times, the team should proceed with offering extracorporeal support, especially in newly diagnosed patients who have not benefitted from medical therapy prior to their acute deterioration, in patients with severe pulmonary venous disease and in patients with alveolar capillary dysplasia. Currently, the only approved mode for extracorporeal support in pediatric patients with PH eligible for lung transplantation is ECMO. To decrease the risks associated with ECMO, and offer potential for increased duration of support, extubation, and rehabilitation, we transitioned four small children with refractory PH from ECMO to a device comprising an oxygenator interposed between the PA and LA. This work describes in great detail our experience with this mode of support with emphasis on exclusion criteria, the implantation procedure, and the post-implantation management.

Impact of Surgical Strategy and Post-Repair Transverse Aortic Arch Size on Late Hypertension After Coarctation Repair During Infancy.

OBJECTIVE: Late HTN after CoA repair contributes to higher morbidity and mortality. An association between TAA hypoplasia and HTN has been found, but its relationship with surgical strategy is unclear. We studied the association between late HTN and initial surgical strategy pertaining to the TAA. METHODS: We retrospectively reviewed patients who underwent surgical repair of CoA during infancy with at least 10 years follow-up, excluding those with atypical coarctation, major associated heart defects, and residual isthmic narrowing. TAA diameter z-score immediately post-repair was measured as a marker of surgical strategy. Systemic HTN at latest follow-up was assessed using standard criteria. RESULTS: A total of 130 patients underwent surgical repair of CoA (76% via thoracotomy, 24% via sternotomy; type of repair - resection and end-to-end anastomosis 62%, extended end-to-end anastomosis 30%, subclavian flap 5%, arch repair with patch 4%), at a median age of 14 (IQR 7-62) days. Median post-repair TAA diameter z-score was -2.04 (IQR -2.69, 1.24). After a mean follow-up of 17.3 years, 43/130 (33%) patients developed HTN. After controlling for age at repair, gender, and presence of a genetic syndrome, HTN was not associated with immediate post-repair TAA diameter z-score, (p=0.41), type of surgical incision (p=0.99), or type of surgical repair (p=0.66). CONCLUSIONS: In patients undergoing surgical repair of CoA during infancy, late HTN was not associated with immediate post-repair TAA size or surgical strategy pertaining to the TAA. These results suggest that factors other than surgical strategy, such as differential growth of the TAA during childhood, may be important.

Development of a Simple Analytical Model to Facilitate Preoperative Surgical Planning in Valve-Sparing Aortic Root Replacement.

PURPOSE: Valve-sparing root replacement (VSRR) is attractive for aortic root dilation as it preserves the native aortic valve (AoV). Low effective height (eH) after reconstruction is a risk factor for repair failure and reoperation. We developed and validated a quantitative AoV repair strategy to reliably restore normal valve proportions to promote long-term function. METHODS: Normal AoV proportions were used to derive geometric relationships for sinotubular junction diameter (DSTJ), free edge length (FEL), free edge angle, and commissure height. These relationships informed two models for predicting eH following VSRR: (1) assuming valve symmetry and (2) accounting for valve asymmetry. Porcine heart (n = 6) ex vivo validation was performed under 4 VSRR scenarios: "Ideal" (tube graft size targeting FEL/DSTJ = 1.28), "Oversized" (one graft size larger than Ideal), "Undersized" (two sizes smaller), and "Undersized + Plicated" (FEL/DSTJ = 1.28 restored with leaflet plication). RESULTS: Our analytical models predicted eH using preoperative measurements and estimated reconstructed dimensions. The Oversized graft exhibited similar eH to Ideal but higher regurgitation in the ex vivo model, whereas the Undersized graft demonstrated lower eH and regurgitation. Plication in the Undersized graft restored valve function (regurgitation & eH) similar to Ideal in the ex vivo model and above Ideal in the analytical models. Both analytical models predicted ex vivo eH well except in the Oversized and Undersized + Plicated conditions. CONCLUSION: Utilizing measurements from preoperative imaging and simple mathematical models, patient-specific operative plans for VSRR can be created by estimating valve dimensions necessary to achieve favorable valve features post-repair. Clinical application of this approach promises to improve consistency in achieving optimal long-term dimensions and durability.

Multiphysiologic State Computational Fluid Dynamics Modeling for Planning Fontan With Interrupted Inferior Vena Cava.

Background: Single ventricle (SV) patients with interrupted inferior vena cava (iIVC) and azygos continuation are at high risk for unbalanced hepatic venous flow (HVF) distribution to the lungs after Fontan completion and subsequent pulmonary arteriovenous malformations (AVMs) formation. Objectives: The aim of the study was to utilize computational fluid dynamics (CFD) analysis to avoid maldistribution of HVF to the lungs after Fontan surgery. Methods: Four SV subjects with iIVC were prospectively studied with a 3-dimensional (3D) modeling workflow with digital 3D models created from segmented magnetic resonance images or computer tomography scans, virtual surgery, and CFD analysis over multiple physiologic states for the evaluation of operative plans to achieve balanced HVF to both lungs. Three of the patients were Fontan revision candidates with existing AVMs. All patients underwent Fontan completion or revision surgery. Results: CFD predicted that existing or proposed Fontan completion in all patients would result in 100% of HVF to one lung. Improved HVF balance was achieved with CFD analysis of alternative surgical approaches resulting in the average distribution of HVF to the right/left pulmonary arteries of 37%/63% ± 10.4%. A hepatoazygos shunt was required in all patients and additional creation of an innominate vein in one. CFD analysis was validated by the comparison of pre-operative predicted and postoperative MRI-measured total right/left pulmonary flow (51%/49% ± 5.4% vs 49%/51% ± 8.5%). Conclusions: A 3D modeling workflow with CFD simulation for SV patients with iIVC may avoid HVF maldistribution and development of AVMs after Fontan completion.

Fiberscope-Based Measurement of Coaptation Height for Intraoperative Assessment of Mitral Valve Repair.

BACKGROUND: Restoring adequate coaptation height is a key principle of mitral valve (MV) repair. This study aimed to evaluate the utility of fiberscope (FS) technology to assess MV coaptation height for intraoperative use. METHODS: Ex-vivo testing was performed on five adult porcine hearts. The left atrium (LA) was resected, and the left ventricle (LV) was pressurized retrograde to 27 ± 1mm Hg. An endoscope was inserted into the LV apex, centered under the MV orifice. An FS system (Milliscope II camera, LED light source, and 0.7 mm diameter × 15 cm long) 90° semirigid scope with 1.2 mm focal length) was mounted above the MV annulus in a custom alignment and measuring fixture. Three blinded measurements were taken at two locations on each MV, A2 and P2 segment, from the top of coaptation to the leaflet edge identified by the FS. Accurate positioning was verified using the LV endoscope. A control (metal rod of similar thickness) was used for comparison, with coaptation height recorded when the control was seen via the endoscope. RESULTS: Coaptation heights were similar for the control and FS methods across all hearts at A2 (11.6 ± 2.6 mm control vs 11.8 ± 2.2 mm FS) and P2 (13.3 ± 2.6 mm control vs 13.4 ± 2.9 mm FS) segments, with similar measurement variability (control SD 0.1-1.0 mm; FS SD 0.1-0.9 mm). One outlier was excluded from analysis (n = 19/20). The maximum absolute difference and percent error between measurement methods were less than 1.1 mm (median [IQR], 0.6 [0.3-0.9] mm) and less than 14% (4.1 [2.2-7.6]%). CONCLUSIONS: Utilization of a miniaturized FS enabled precise and accurate quantification of MV coaptation. This technique is promising for evaluating post-repair valve competence and coaptation height.

Association of tetralogy of Fallot and complete atrioventricular canal: a single-centre 40-year experience.

OBJECTIVES: Outcome data in tetralogy of Fallot (ToF) and complete atrioventricular canal (CAVC) are limited. We report our experience for over 40 years in this patient population. METHODS: Single-centre, retrospective analysis of patients who underwent surgical repair with the diagnosis of ToF-CAVC from 1979 to 2022, divided into 2 different periods and compared. RESULTS: A total of 116 patients were included: 1979-2007 (n = 61) and 2008-2021 (n = 55). Balanced CAVC (80%) and Rastelli type C CAVC (81%) were most common. Patients in the later era were younger (4 vs 14 months, P < 0.001), fewer had trisomy 21 (60% vs 80%, P = 0.019) and fewer had prior palliative prior procedures (31% vs 43%, P < 0.001). In the earlier era, single-patch technique was more common (62% vs 16%, P < 0.001), and in recent era, double-patch technique was more common (84% vs 33%, P < 0.001). In the earlier era, right ventricular outflow tract was most commonly reconstructed with transannular patch (51%), while in more recent era, valve-sparing repairs were more common (69%) (P < 0.001). In-hospital mortality was 4.3%. The median follow-up was 217 and 74 months for the first and second eras. Survival for earlier and later eras at 2-, 5- and 10-year follow-up was (85.1%, 81.5%, 79.6% vs 94.2%, 94.2%, 94.2% respectively, log-rank test P = 0.03). CONCLUSIONS: The surgical approach to ToF-CAVC has evolved over time. More recently, patients tended to receive primary repair at younger ages and had fewer palliative procedures. Improved surgical techniques allowing for earlier and complete repair have shown a decrease in mortality, more valve-sparing procedures without an increase in total reoperations. Presented at the 37th EACTS Annual Meeting, Vienna, Austria.

Toward trustworthy medical device in silico clinical trials: a hierarchical framework for establishing credibility and strategies for overcoming key challenges.

Computational models of patients and medical devices can be combined to perform an in silico clinical trial (ISCT) to investigate questions related to device safety and/or effectiveness across the total product life cycle. ISCTs can potentially accelerate product development by more quickly informing device design and testing or they could be used to refine, reduce, or in some cases to completely replace human subjects in a clinical trial. There are numerous potential benefits of ISCTs. An important caveat, however, is that an ISCT is a virtual representation of the real world that has to be shown to be credible before being relied upon to make decisions that have the potential to cause patient harm. There are many challenges to establishing ISCT credibility. ISCTs can integrate many different submodels that potentially use different modeling types (e.g., physics-based, data-driven, rule-based) that necessitate different strategies and approaches for generating credibility evidence. ISCT submodels can include those for the medical device, the patient, the interaction of the device and patient, generating virtual patients, clinical decision making and simulating an intervention (e.g., device implantation), and translating acute physics-based simulation outputs to health-related clinical outcomes (e.g., device safety and/or effectiveness endpoints). Establishing the credibility of each ISCT submodel is challenging, but is nonetheless important because inaccurate output from a single submodel could potentially compromise the credibility of the entire ISCT. The objective of this study is to begin addressing some of these challenges and to identify general strategies for establishing ISCT credibility. Most notably, we propose a hierarchical approach for assessing the credibility of an ISCT that involves systematically gathering credibility evidence for each ISCT submodel in isolation before demonstrating credibility of the full ISCT. Also, following FDA Guidance for assessing computational model credibility, we provide suggestions for ways to clearly describe each of the ISCT submodels and the full ISCT, discuss considerations for performing an ISCT model risk assessment, identify common challenges to demonstrating ISCT credibility, and present strategies for addressing these challenges using our proposed hierarchical approach. Finally, in the Appendix we illustrate the many concepts described here using a hypothetical ISCT example.

Impact of Age-Related Change in Caval Flow Ratio on Hepatic Flow Distribution in the Fontan Circulation.

BACKGROUND: The Fontan operation is a palliative technique for patients born with single ventricle heart disease. The superior vena cava (SVC), inferior vena cava (IVC), and hepatic veins are connected to the pulmonary arteries in a total cavopulmonary connection by an extracardiac conduit or a lateral tunnel connection. A balanced hepatic flow distribution (HFD) to both lungs is essential to prevent pulmonary arteriovenous malformations and cyanosis. HFD is highly dependent on the local hemodynamics. The effect of age-related changes in caval inflows on HFD was evaluated using cardiac magnetic resonance data and patient-specific computational fluid dynamics modeling. METHODS: SVC and IVC flow from 414 patients with Fontan were collected to establish a relationship between SVC:IVC flow ratio and age. Computational fluid dynamics modeling was performed in 60 (30 extracardiac and 30 lateral tunnel) patient models to quantify the HFD that corresponded to patient ages of 3, 8, and 15 years, respectively. RESULTS: SVC:IVC flow ratio inverted at ≈8 years of age, indicating a clear shift to lower body flow predominance. Our data showed that variation of HFD in response to age-related changes in caval inflows (SVC:IVC, 2, 1, and 0.5 corresponded to ages, 3, 8, and 15+, respectively) was not significant for extracardiac but statistically significant for lateral tunnel cohorts. For all 3 caval inflow ratios, a positive correlation existed between the IVC flow distribution to both the lungs and the HFD. However, as the SVC:IVC ratio changed from 2 to 0.5 (age, 3-15+) years, the correlation's strength decreased from 0.87 to 0.64, due to potential flow perturbation as IVC flow momentum increased. CONCLUSIONS: Our analysis provided quantitative insights into the impact of the changing caval inflows on Fontan's long-term HFD, highlighting the importance of SVC:IVC variations over time on Fontan's long-term hemodynamics. These findings broaden our understanding of Fontan hemodynamics and patient outcomes.

Validation of a laser projection platform for the preparation of surgical patches used in paediatric cardiac surgery.

OBJECTIVES: Reconstruction of cardiovascular anatomy with patch material is integral to the repair of congenital heart disease. We present validation of a laser projection platform for the preparation of surgical patches as a proof-of-concept for intraoperative use in patient-specific planning of paediatric cardiac surgery reconstructions. METHODS: The MicroLASERGUIDE, a compact laser projection system that displays computer-aided designs onto 2D/3D surfaces, serves as an alternative to physical templates. A non-inferiority comparison of dimensional measurements was conducted between laser projection ('laser') and OZAKI AVNeo Template ('template') methods in creation of 51 (each group) size 13 valve leaflets from unfixed bovine pericardium. A digital version of the OZAKI AVNeo Template dimensions served as control. Feasibility testing was performed with other common patch materials (fixed bovine pericardium, PTFE and porcine main pulmonary artery as a substitute for pulmonary homograft) and sizes (13, 23) (n = 3 each group). RESULTS: Compared to control (height 21.5, length 21.0 mm), template height and length were smaller (height and length differences of -0.3 [-0.5 to 0.0] and -0.4 [-0.8 to -0.1] mm, P < 0.01 each); whereas, both laser height and length were relatively similar (height and length differences of height 0.0 [-0.2 to 0.2], P = 0.804, and 0.2 [-0.1 to 0.4] mm, P = 0.029). Template percent error for height and length was -1.5 (-2.3 to 0.0)% and -1.9 (-3.7 to -0.6)% vs 0.2 (-1.0 to 1.1)% and 1.0 (-0.5 to 1.8)% for the laser. Similar results were found with other materials and sizes. Overall, laser sample dimensions differed by a maximum of 5% (∼1 mm) from the control. CONCLUSIONS: The laser projection platform has demonstrated promise as an alternative methodology for the preparation of surgical patches for use in cardiac surgery. This technology has potential to revolutionize preoperative surgical planning for numerous congenital anomalies that require patient-specific patch-augmented repair.

Timing of reintervention influences survival and resource utilization following first-stage palliation of single ventricle heart disease.

OBJECTIVE: Outcomes after first-stage palliation of single-ventricle heart disease are influenced by many factors, including the presence of residual lesions requiring reintervention. However, there is a dearth of information regarding the optimal timing of reintervention. We assessed if earlier reintervention would be favorably associated with in-hospital outcomes among patients requiring unplanned reinterventions after the Norwood operation. METHODS: This was a single-center, retrospective review of all patients who underwent the Norwood procedure from January 1997 to November 2017 and required a predischarge unplanned surgical or transcatheter reintervention on 1 or more subcomponent areas repaired at the index operation. Outcomes of interest included in-hospital mortality or transplant, postoperative hospital length of stay, and inpatient cost. Associations between timing of reintervention and outcomes were assessed using logistic regression (mortality or transplant) or generalized linear models (postoperative hospital length of stay and cost), adjusting for baseline patient-related and procedural factors. RESULTS: Of 500 patients who underwent the Norwood operation, 92 (18.4%) required an unplanned reintervention. Median time to reintervention was 12 days (interquartile range, 5-35 days). There were 31 (33.7%) deaths or transplants, median postoperative hospital length of stay was 49 days (interquartile range, 32-87 days), and median cost was $328,000 (interquartile range, $204,000-$464,000). On multivariable analysis, each 5-day increase in time to reintervention increased the odds of mortality or transplant by 20% (odds ratio, 1.2; 95% confidence interval, 1.1-1.3; P = .004). Longer time to reintervention was also significantly associated with greater postoperative hospital length of stay (P < .001) and higher cost (P < .001). CONCLUSIONS: For patients requiring predischarge unplanned reinterventions after the Norwood operation, earlier reintervention is associated with improved in-hospital transplant-free survival and resource use.

Aortic growth after arch reconstruction with patch augmentation: a 2-decade experience.

OBJECTIVES: Optimal aortic sizing during aortic arch reconstruction remains unknown. Negative effects of arch under- or oversizing are well-published. We aimed to characterize longitudinal aortic growth after patch-augmented arch reconstruction to identify the initial reconstructed arch size that results in normal mid-term arch dimensions. METHODS: Single-centre, retrospective review of infants undergoing Damus-Kaye-Stansel (DKS) or non-DKS patch-augmented aortic arch reconstruction between 2000 and 2021. Ascending aorta, proximal and distal transverse arch, aortic isthmus (AIsth) and descending aorta dimensions were measured in postoperative echocardiograms (<3 months from index operation) and cross-sectional imaging (>12 months). Longitudinal changes to aortic dimensions and z-scores were analysed. Secondary outcomes included reintervention, valve and ventricular function, mortality and transplantation. RESULTS: Fifty-four patients (16 DKS, 38 non-DKS) were included. At 6.3 [2.2, 12.0]-year follow-up, all aortic segments grew significantly in both groups, while z-scores remained unchanged except for non-DKS proximal and distal transverse arch z-scores, which significantly increased (P < 0.05 each). When stratified by initial postoperative z-score (z < -1, -1 ≤ z ≤ 1, z > 1), non-DKS patients with initial AIsth z-score <-1 had a final z-score significantly smaller than both the targeted z-score zero (P = 0.014) and final z-score in a group with initial postoperative z-score ±1 (P = 0.009). Valve and ventricular function remained stable. Eighteen patients required reintervention, 1 died and 1 underwent transplant. CONCLUSIONS: Over mid-term follow-up, aortic growth after arch reconstruction with patch augmentation was proportional when repaired to normal z-score dimensions, aside from proximal transverse arch, which disproportionately dilated. AIsth undersizing prevailed mid-term and trended towards a higher reintervention rate. Initial reconstruction between z-score 0 and +1 resulted in maintenance of that z-score size at mid-term follow-up. Overall, it is crucial to achieve targeted aortic sizing at index operation to maintain appropriate aortic dimensions over time and reduce reintervention risk with specific focus on the AIsth.

Transcatheter Pulmonary Artery Banding in High-Risk Neonates: In-Vitro Study Provoked by Initial Clinical Experience.

PURPOSE: Very high-risk, ductal-dependent or complex two-ventricle patients with associated comorbidities often require pulmonary blood flow restriction as bridge to a more definitive procedure, but current surgical options may not be well-tolerated. An evolving alternative utilizes a fenestrated Micro Vascular Plug (MVP) as a transcatheter, internal pulmonary artery band. In this study, we report a case series and an in-vitro evaluation of the MVP to elicit understanding of the challenges faced with device implantation. METHODS: Following single-center, retrospective review of eight patients who underwent device placement, an in-vitro flow study was conducted on MVP devices to assess impact of device and fenestration sizing on pulmonary blood flow. A mathematical model was developed to relate migration risk to vessel size. Results of the engineering analysis were compared to the clinical series for validation. RESULTS: At median follow-up of 8 months (range 1-15), survival was 63% (5/8), and 6 (75%) patients underwent subsequent target surgical intervention with relatively low mortality (1/6). Occluder-related challenges included migration (63%) and peri-device flow, which were evaluated in-vitro. The device demonstrated durability over normal and supraphysiologic conditions with minimal change in fenestration size. Smaller vessel size significantly increased pressure gradient due to reduced peri-device flow and smaller effective fenestration size. CONCLUSION: Device oversizing, with appropriate adjustment to fenestration size, may reduce migration risk and provide a clinically appropriate balance between resulting pressure gradient and Qp:Qs. Our results can guide the interventionalist in appropriately selecting the device and fenestrations based on patient-specific anatomy and desired post-implantation flow characteristics.

A multifunctional soft robot for cardiac interventions.

In minimally invasive endovascular procedures, surgeons rely on catheters with low dexterity and high aspect ratios to reach an anatomical target. However, the environment inside the beating heart presents a combination of challenges unique to few anatomic locations, making it difficult for interventional tools to maneuver dexterously and apply substantial forces on an intracardiac target. We demonstrate a millimeter-scale soft robotic platform that can deploy and self-stabilize at the entrance to the heart, and guide existing interventional tools toward a target site. In two exemplar intracardiac procedures within the right atrium, the robotic platform provides enough dexterity to reach multiple anatomical targets, enough stability to maintain constant contact on motile targets, and enough mechanical leverage to generate newton-level forces. Because the device addresses ongoing challenges in minimally invasive intracardiac intervention, it may enable the further development of catheter-based interventions.

An In Vitro Circulatory Loop Model of the Pediatric Right Ventricular Outflow Tract as a Platform for Valve Evaluation.

PURPOSE: Tetralogy of Fallot and other conditions affecting the right ventricular outflow tract (RVOT) are common in pediatric patients, but there is a lack of quantitative comparison among techniques for repairing or replacing the pulmonary valve. The aim of this study was to develop a robust in vitro system for quantifying flow conditions after various RVOT interventions. METHODS: An infant-sized mock circulatory loop that includes a 3D-printed RVOT anatomical model was developed to evaluate flow conditions after different simulated surgical repairs. Physiologically correct flow and pressure were achieved with custom compliant tubing and a tunable flow restrictor. Pressure gradient, flow regurgitation, and coaptation height were measured for two monocusp leaflet designs after tuning the system with a 12 mm Hancock valved conduit. RESULTS: Measurements were repeatable across multiple samples of two different monocusp designs, with the wider leaflet in the 50% backwall model consistently exhibiting lower pressure gradient but higher regurgitation compared to the leaflet in the 40% backwall model. Coaptation height was measured via direct visualization with endoscopic cameras, revealing a shorter area of contact for the wider leaflet (3.3-4.0 mm) compared to the narrower one (4.3 mm). CONCLUSION: The 3D-printed RVOT anatomical model and in vitro pulmonary circulatory loop developed in this work provide a platform for planning and evaluating surgical interventions in the pediatric population. Measurements of regurgitation, pressure gradient, and coaptation provide a quantitative basis for comparison among different valve designs and positions.