Effect of graft sizing in valve-sparing aortic root replacement for bicuspid aortic valve: The Goldilocks ratio.

Objective: To investigate the effect of graft sizing on valve performance in valve-sparing aortic root replacement for bicuspid aortic valve. Methods: In addition to a diseased control model, 3 representative groups-free-edge length to aortic/graft diameter (FELAD) ratio <1.3, 1.5 to 1.64, and >1.7-were replicated in explanted porcine aortic roots (n = 3) using straight grafts sized respective to the native free-edge length. They were run on a validated ex vivo univentricular system under physiological parameters for 20 cycles. All groups were tested within the same aortic root to minimize inter-root differences. Outcomes included transvalvular gradient, regurgitation fraction, and orifice area. Linear mixed effects model and pairwise comparisons were employed to compare outcomes across groups. Results: The diseased control had mean transvalvular gradient 10.9 ± 6.30 mm Hg, regurgitation fraction 32.5 ± 4.91%, and orifice area 1.52 ± 0.12 cm2. In ex vivo analysis, all repair groups had improved regurgitation compared with control (P < .001). FELAD <1.3 had the greatest amount of regurgitation among the repair groups (P < .001) and 1.5-1.64 the least (P < .001). FELAD <1.3 and >1.7 exhibited greater mean gradient compared with both control and 1.5 to 1.64 (P < .001). Among the repair groups, 1.5 to 1.64 had the largest orifice area, and >1.7 the smallest (P < .001). Conclusions: For a symmetric bicuspid aortic valve, performance after valve-sparing aortic root replacement shows a bimodal distribution across graft size. As the FELAD ratio departs from 1.5 to 1.64 in either direction, significant increases in transvalvular gradient are observed. FELAD <1.3 may also result in suboptimal improvement of baseline regurgitation.

Simulation-based design of bicuspidization of the aortic valve.

OBJECTIVE: Severe congenital aortic valve pathology in the growing patient remains a challenging clinical scenario. Bicuspidization of the diseased aortic valve has proven to be a promising repair technique with acceptable durability. However, most understanding of the procedure is empirical and retrospective. This work seeks to design the optimal gross morphology associated with surgical bicuspidization with simulations based on the hypothesis that modifications to the free edge length cause or relieve stenosis. METHODS: Model bicuspid valves were constructed with varying free edge lengths and gross morphology. Fluid-structure interaction simulations were conducted in a single patient-specific model geometry. The models were evaluated for primary targets of stenosis and regurgitation. Secondary targets were assessed and included qualitative hemodynamics, geometric height, effective height, orifice area, and billow. RESULTS: Stenosis decreased with increasing free edge length and was pronounced with free edge length less than or equal to 1.3 times the annular diameter d. With free edge length 1.5d or greater, no stenosis occurred. All models were free of regurgitation. Substantial billow occurred with free edge length 1.7d or greater. CONCLUSIONS: Free edge length 1.5d or greater was required to avoid aortic stenosis in simulations. Cases with free edge length 1.7d or greater showed excessive billow and other changes in gross morphology. Cases with free edge length 1.5d to 1.6d have a total free edge length approximately equal to the annular circumference and appeared optimal. These effects should be studied in vitro and in animal studies.

SDF4CHD: Generative Modeling of Cardiac Anatomies with Congenital Heart Defects.

Congenital heart disease (CHD) encompasses a spectrum of cardiovascular structural abnormalities, often requiring customized treatment plans for individual patients. Computational modeling and analysis of these unique cardiac anatomies can improve diagnosis and treatment planning and may ultimately lead to improved outcomes. Deep learning (DL) methods have demonstrated the potential to enable efficient treatment planning by automating cardiac segmentation and mesh construction for patients with normal cardiac anatomies. However, CHDs are often rare, making it challenging to acquire sufficiently large patient cohorts for training such DL models. Generative modeling of cardiac anatomies has the potential to fill this gap via the generation of virtual cohorts; however, prior approaches were largely designed for normal anatomies and cannot readily capture the significant topological variations seen in CHD patients. Therefore, we propose a type- and shape-disentangled generative approach suitable to capture the wide spectrum of cardiac anatomies observed in different CHD types and synthesize differently shaped cardiac anatomies that preserve the unique topology for specific CHD types. Our DL approach represents generic whole heart anatomies with CHD type-specific abnormalities implicitly using signed distance fields (SDF) based on CHD type diagnosis, which conveniently captures divergent anatomical variations across different types and represents meaningful intermediate CHD states. To capture the shape-specific variations, we then learn invertible deformations to morph the learned CHD type-specific anatomies and reconstruct patient-specific shapes. Our approach has the potential to augment the image-segmentation pairs for rarer CHD types for cardiac segmentation and generate cohorts of CHD cardiac meshes for computational simulation.

Simulation-Based Design of Bicuspidization of the Aortic Valve.

OBJECTIVE: Severe congenital aortic valve pathology in the growing patient remains a challenging clinical scenario. Bicuspidization of the diseased aortic valve has proven to be a promising repair technique with acceptable durability. However, most understanding of the procedure is empirical and retrospective. This work seeks to design the optimal gross morphology associated with surgical bicuspidization with simulations, based on the hypothesis that modifications to the free edge length cause or relieve stenosis. METHODS: Model bicuspid valves were constructed with varying free edge lengths and gross morphology. Fluid-structure interaction simulations were conducted in a single patient-specific model geometry. The models were evaluated for primary targets of stenosis and regurgitation. Secondary targets were assessed and included qualitative hemodynamics, geometric height, effective height, orifice area and prolapse. RESULTS: Stenosis decreased with increasing free edge length and was pronounced with free edge length less than or equal to 1.3 times the annular diameter d. With free edge length 1.5d or greater, no stenosis occurred. All models were free of regurgitation. Substantial prolapse occurred with free edge length greater than or equal to 1.7d. CONCLUSIONS: Free edge length greater than or equal to 1.5d was required to avoid aortic stenosis in simulations. Cases with free edge length greater than or equal to 1.7d showed excessive prolapse and other changes in gross morphology. Cases with free edge length 1.5-1.6d have a total free edge length approximately equal to the annular circumference and appeared optimal. These effects should be studied in vitro and in animal studies.

Diversifying cardiac intensive care unit models: Successful example of an operating surgeon-led unit.

Objective: The intensivist-led cardiovascular intensive care unit model is the standard of care in cardiac surgery. This study examines whether a cardiovascular intensive care unit model that uses operating cardiac surgeons, cardiothoracic surgery residents, and advanced practice providers is associated with comparable outcomes. Methods: This is a single-institution review of the first 400 cardiac surgery patients admitted to an operating surgeon-led cardiovascular intensive care unit from 2020 to 2022. Inclusion criteria are elective status and operations managed by both cardiovascular intensive care unit models (aortic operations, valve operations, coronary operations, septal myectomy). Patients from the surgeon-led cardiovascular intensive care unit were exact matched by operation type and 1:1 propensity score matched with controls from the traditional cardiovascular intensive care unit using a logistic regression model that included age, sex, preoperative mortality risk, incision type, and use of cardiopulmonary bypass and circulatory arrest. Primary outcome was total postoperative length of stay. Secondary outcomes included postoperative intensive care unit length of stay, 30-day mortality, 30-day Society of Thoracic Surgeons-defined morbidity (permanent stroke, renal failure, cardiac reoperation, prolonged intubation, deep sternal infection), packed red cell transfusions, and vasopressor use. Outcomes between the 2 groups were compared using chi-square, Fisher exact test, or 2-sample t test as appropriate. Results: A total of 400 patients from the surgeon-led cardiovascular intensive care unit (mean age 61.2 ± 12.8 years, 131 female patients [33%], 346 patients [86.5%] with European System for Cardiac Operative Risk Evaluation II <2%) and their matched controls were included. The most common operations across both units were coronary artery bypass grafting (n = 318, 39.8%) and mitral valve repair or replacement (n = 238, 29.8%). Approximately half of the operations were performed via sternotomy (n = 462, 57.8%). There were 3 (0.2%) in-hospital deaths, and 47 patients (5.9%) had a 30-day complication. The total length of stay was significantly shorter for the surgeon-led cardiovascular intensive care unit patients (6.3 vs 7.0 days, P = .028), and intensive care unit length of stay trended in the same direction (2.5 vs 2.9 days, P = .16). Intensive care unit readmission rates, 30-day mortality, and 30-day morbidity were not significantly different between cardiovascular intensive care unit models. The surgeon-led cardiovascular intensive care unit was associated with fewer postoperative red blood cell transfusions in the cardiovascular intensive care unit (P = .002) and decreased vasopressor use (P = .001). Conclusions: In its first 2 years, the surgeon-led cardiovascular intensive care unit demonstrated comparable outcomes to the traditional cardiovascular intensive care unit with significant improvements in total length of stay, postoperative transfusions in the cardiovascular intensive care unit, and vasopressor use. This early success exemplifies how an operating surgeon-led cardiovascular intensive care unit can provide similar outcomes to the standard-of-care model for patients undergoing elective cardiac surgery.

Innominate artery patency after direct cannulation in neonates.

Objective: The study objective was to determine the short-term incidence of innominate artery stenosis for neonates who underwent direct innominate artery cannulation during the Norwood procedure. Methods: This is a retrospective, single-institution review of 92 patients who underwent the Norwood procedure with direct innominate artery cannulation from 2006 to 2017. The primary outcome was angiographic evidence of patency at pre-Glenn cardiac catheterization. Patient characteristics, intraoperative surgical and hemodynamic measurements, and postoperative neurologic findings were recorded. Results: At a median age of 5.0 days, 92 neonates underwent the Norwood procedure with direct innominate artery cannulation. These patients underwent cardiac catheterization at a median of 3.0 months after the index operation. In 5 of 92 patients with catheterization images available for review, there was angiographic evidence of mild innominate artery stenosis, and none had moderate or severe stenosis. Review of follow-up records did not reveal evidence of clinically significant stenosis or innominate artery reintervention. Conclusions: In neonates undergoing the Norwood procedure with direct innominate cannulation, innominate artery stenosis was uncommon and clinically significant stenosis did not occur.

Revisiting prosthesis choice in mitral valve replacement in children: Durable alternatives to traditional bioprostheses.

OBJECTIVE: To determine risk factors for re-replacement and death or transplant following mitral valve replacement (MVR) in children METHODS: This is a retrospective 26-year review of patients younger than 20 years of age undergoing MVR between 1992 and 2018 at single institution. Outcomes included freedom from re-MVR and transplant-free survival. Cox proportional hazards regression models assessed association between outcomes and potential risk factors. RESULTS: At median age 4.2 years, 190 children underwent 290 MVR: 180 mechanical, 63 porcine, 13 pericardial, and 34 stented bovine jugular vein valves. Re-MVR occurred in 100 valves. Freedom from re-MVR at 5 and 10 years was 76% and 44%. Times to re-MVR were associated with prosthesis type (P < .001), with porcine and pericardial valves at greatest risk. Other risk factors for prosthetic failure included smaller prosthesis size and left ventricular hypoplasia. There were 9 transplants and 44 deaths. Transplant-free survival at 5 and 10 years was 81% and 76%. Prosthesis type was significantly associated with time to death/transplant in univariate analysis only (P = .021), with porcine at greater risk than mechanical. Independent risk factors for death/transplant included larger indexed geometric orifice area and longer bypass time. CONCLUSIONS: In pediatric patients undergoing MVR, mechanical and stented bovine jugular vein valves were associated with increased durability compared with fixed-diameter bioprosthetic alternatives.

Three-Dimensional Modeling of Surgically Implanted Stent-Based Valves in the Mitral Position in Children.

PURPOSE: In children with a mitral annulus too small to accommodate traditional prostheses, surgical implantation of stent-based valves is a promising option. However no reliable preoperative methods exist to guide patient selection, device sizing, and positioning. We describe a novel methodology to visualize and quantify device fit in 3-dimensional echocardiogram (3DE)-derived heart models. DESCRIPTION: Heart models were created from existing preoperative 3DEs using custom software. Valve models were virtually implanted into the models, and both device fit and left ventricular outflow tract (LVOT) area were quantified. EVALUATION: The 3DEs of 3 patients who underwent Melody valve placement in the mitral position were retrospectively modeled: 1 with LVOT obstruction, 1 with perivalvar leak, and 1 without complications. In all cases 2-dimensional measurements underestimated 3D annular dimensions, and the patient with clinical LVOT obstruction had the lowest predicted LVOT area-to-aortic area ratio (0.5). CONCLUSIONS: 3DE-based preoperative modeling of surgical implantation of stent-based valves in the mitral position may improve quantification of mitral valve dimensions and inform risk stratification for potential LVOT obstruction.

Magnetic Resonance-Based Diagnostics for Bleeding Assessment in Neonatal Cardiac Surgery.

PURPOSE: Infants undergoing a cardiac operation are at high risk for postsurgical bleeding. To date, there are no highly predictive models for postsurgical bleeding in this population. This study's objective was to assess the predictive ability of T2 magnetic resonance (T2MR). DESCRIPTION: T2MR uses magnetic resonance to detect clot formation characteristics on a small blood sample and provides hemostatic indicators that can assess bleeding risk. EVALUATION: This prospective, single-institution study enrolled 100 patients younger than 12 months old undergoing a cardiac operation from April 27, 2015, to September 21, 2016. The primary end point was postsurgical bleeding within 24 hours after the procedure. T2MR data were modeled with a binary recursive partitioning algorithm with randomized cross-validation. The tight clot metric produced the highest univariate discrimination of bleeding (receiver operator characteristic curve, 0.64; classification accuracy, 72%), and along with the platelet function metric, demonstrated highest relative importance based on Gini index splitting (Salford Systems, San Diego, CA). Multivariate modeling with cross-validation showed mean receiver operator characteristic curve area of 0.74 and classification accuracy of 82%. CONCLUSIONS: T2MR tight clot and platelet function metrics were associated with bleeding events.