3D models of the cardiac conduction system in healthy neonatal human hearts.

Iatrogenic damage to the cardiac conduction system (CCS) remains a significant risk during congenital heart surgery. Current surgical best practice involves using superficial anatomical landmarks to locate and avoid damaging the CCS. Prior work indicates inherent variability in the anatomy of the CCS and supporting tissues. This study introduces high-resolution, 3D models of the CCS in normal pediatric human hearts to evaluate variability in the nodes and surrounding structures. Human pediatric hearts were obtained with an average donor age of 2.7 days. A pipeline was developed to excise, section, stain, and image atrioventricular (AVN) and sinus nodal (SN) tissue regions. A convolutional neural network was trained to enable precise multi-class segmentation of whole-slide images, which were subsequently used to generate high- resolution 3D tissue models. Nodal tissue region models were created. All models (10 AVN, 8 SN) contain tissue composition of neural tissue, vasculature, and nodal tissues at micrometer resolution. We describe novel nodal anatomical variations. We found that the depth of the His bundle in females was on average 304 µm shallower than those of male patients. These models provide surgeons with insight into the heterogeneity of the nodal regions and the intricate relationships between the CCS and surrounding structures.

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.

Transcatheter Palliation With Pulmonary Artery Flow Restrictors in Neonates With Congenital Heart Disease: Feasibility, Outcomes, and Comparison With a Historical Hybrid Stage 1 Cohort.

BACKGROUND: Neonates with complex congenital heart disease and pulmonary overcirculation have been historically treated surgically. However, subcohorts may benefit from less invasive procedures. Data on transcatheter palliation are limited. METHODS: We present our experience with pulmonary flow restrictors (PFRs) for palliation of neonates with congenital heart disease, including procedural feasibility, technical details, and outcomes. We then compared our subcohort of high-risk single ventricle neonates palliated with PFRs with a similar historical cohort who underwent a hybrid Stage 1. Cox regression was used to evaluate the association between palliation strategy and 6-month mortality. RESULTS: From 2021 to 2023, 17 patients (median age, 4 days; interquartile range [IQR], 2-8; median weight, 2.5 kilograms [IQR, 2.1-3.3]) underwent a PFR procedure; 15 (88%) had single ventricle physiology; 15 (88%) were high-risk surgical candidates. All procedures were technically successful. At a median follow-up of 6.2 months (IQR, 4.0-10.8), 13 patients (76%) were successfully bridged to surgery (median time since PFR procedure, 2.6 months [IQR, 1.1-4.4]; median weight, 4.9 kilograms [IQR, 3.4-5.8]). Pulmonary arteries grew adequately for age, and devices were easily removed without complications. The all-cause mortality rate before target surgery was 24% (n=4). Compared with the historical hybrid stage 1 cohort (n=23), after adjustment for main confounding (age, weight, intact/severely restrictive atrial septum or left ventricle to coronary fistulae), the PFR procedure was associated with a significantly lower all-cause 6-month mortality risk (adjusted hazard ratio, 0.26 [95% CI, 0.08-0.82]). CONCLUSIONS: Transcatheter palliation with PFR is feasible, safe, and represents an effective strategy for bridging high-risk neonates with congenital heart disease to surgical palliation, complete repair, or transplant while allowing for clinical stabilization and somatic growth.

Cost of Pacing in Pediatric Patients With Postoperative Heart Block After Congenital Heart Surgery.

Importance: Surgical correction of congenital heart defects (CHDs) has improved the lifespan and quality of life of pediatric patients. The number of congenital heart surgeries (CHSs) in children has grown continuously since the 1960s. This growth has been accompanied by a rise in the incidence of postoperative heart block requiring permanent pacemaker (PPM) implantation. Objective: To assess the trends in permanent pacing after CHS and estimate the economic burden to patients and their families after PPM implantation. Design, Setting, and Participants: In this economic evaluation study, procedure- and diagnosis-specific codes within a single-institution database were used to identify patients with postoperative heart block after CHS between January 1, 1960, and December 31, 2018. Patients younger than 4 years with postoperative PPM implantation were selected, and up to 20-year follow-up data were used for cost analysis based on mean hospital event charges and length of stay (LOS) data. Data were analyzed from January 1, 2020, to November 30, 2022. Exposure: Implantation of PPM after CHS in pediatric patients. Main Outcomes and Measures: Annual trends in CHS and postoperative PPM implantations were assessed. Direct and indirect costs associated with managing conduction health for the 20 years after PPM implantation were estimated using Markov model simulation and patient follow-up data. Results: Of the 28 225 patients who underwent CHS, 968 (437 female [45.1%] and 531 male [54.9%]; 468 patients aged <4 years) received a PPM due to postoperative heart block. The rate of CHS and postoperative PPM implantations increased by 2.2% and 7.2% per year between 1960 and 2018, respectively. In pediatric patients younger than 4 years with PPM implantation, the mean (SD) 20-year estimated direct and indirect costs from Markov model simulations were $180 664 ($32 662) and $15 939 ($1916), respectively. Using follow-up data of selected patients with clinical courses involving 1 or more complication events, the mean (SD) direct and indirect costs were $472 774 ($212 095) and $36 429 ($16 706), respectively. Conclusions and Relevance: In this economic evaluation study, the cost of PPM implantation in pediatric patients was found to accumulate over the lifespan. This cost may represent not only a substantial financial burden but also a health care burden to patient families. Reducing the incidence of PPM implantation should be a focused goal of CHS.

Recommendations for Centers Performing Pediatric Heart Surgery in the United States.

Care and outcomes for the more than 40,000 patients undergoing pediatric and congenital heart surgery in the United States annually are known to vary widely. While consensus recommendations have been published across numerous fields as one mechanism to promote a high level of care delivery across centers, it has been more than two decades since the last pediatric heart surgery recommendations were published in the United States. More recent guidance is lacking, and collaborative efforts involving the many disciplines engaged in caring for these children have not been undertaken to date. The present initiative brings together professional societies spanning numerous care domains and congenital cardiac surgeons, pediatric cardiologists, nursing, and other healthcare professionals from diverse programs around the country to develop consensus recommendations for United States centers. The focus of this initial work is on pediatric heart surgery, and it is recommended that future efforts focus in detail on the adult congenital population. We describe the background, rationale, and methodology related to this collaborative effort, and recommendations put forth for Essential Care Centers (essential services necessary for any program), and Comprehensive Care Centers (services to optimize comprehensive and high-complexity care), encompassing structure, process, and outcome metrics across 14 domains.

Recommendations for centers performing pediatric heart surgery in the United States.

Care and outcomes for the more than 40,000 patients undergoing pediatric and congenital heart surgery in the United States annually are known to vary widely. While consensus recommendations have been published across numerous fields as one mechanism to promote a high level of care delivery across centers, it has been more than two decades since the last pediatric heart surgery recommendations were published in the United States. More recent guidance is lacking, and collaborative efforts involving the many disciplines engaged in caring for these children have not been undertaken to date. The present initiative brings together professional societies spanning numerous care domains and congenital cardiac surgeons, pediatric cardiologists, nursing, and other healthcare professionals from diverse programs around the country to develop consensus recommendations for United States centers. The focus of this initial work is on pediatric heart surgery, and it is recommended that future efforts focus in detail on the adult congenital population. We describe the background, rationale, and methodology related to this collaborative effort, and recommendations put forth for Essential Care Centers (essential services necessary for any program), and Comprehensive Care Centers (services to optimize comprehensive and high-complexity care), encompassing structure, process, and outcome metrics across 14 domains.

Recommendations for Centers Performing Pediatric Heart Surgery in the United States.

Care and outcomes for the more than 40,000 patients undergoing pediatric and congenital heart surgery in the United States annually are known to vary widely. While consensus recommendations have been published across numerous fields as one mechanism to promote a high level of care delivery across centers, it has been more than two decades since the last pediatric heart surgery recommendations were published in the United States. More recent guidance is lacking, and collaborative efforts involving the many disciplines engaged in caring for these children have not been undertaken to date. The present initiative brings together professional societies spanning numerous care domains and congenital cardiac surgeons, pediatric cardiologists, nursing, and other healthcare professionals from diverse programs around the country to develop consensus recommendations for United States centers. The focus of this initial work is on pediatric heart surgery, and it is recommended that future efforts focus in detail on the adult congenital population. We describe the background, rationale, and methodology related to this collaborative effort, and recommendations put forth for Essential Care Centers (essential services necessary for any program), and Comprehensive Care Centers (services to optimize comprehensive and high-complexity care), encompassing structure, process, and outcome metrics across 14 domains.

A novel ex vivo tracheobronchomalacia model for airway stent testing and in vivo model refinement.

OBJECTIVES: We sought to develop an ex vivo trachea model capable of producing mild, moderate, and severe tracheobronchomalacia for optimizing airway stent design. We also aimed to determine the amount of cartilage resection required for achieving different tracheobronchomalacia grades that can be used in animal models. METHODS: We developed an ex vivo trachea test system that enabled video-based measurement of internal cross-sectional area as intratracheal pressure was cyclically varied for peak negative pressures of 20 to 80 cm H2O. Fresh ovine tracheas were induced with tracheobronchomalacia by single mid-anterior incision (n = 4), mid-anterior circumferential cartilage resection of 25% (n = 4), and 50% per cartilage ring (n = 4) along an approximately 3-cm length. Intact tracheas (n = 4) were used as control. All experimental tracheas were mounted and experimentally evaluated. In addition, helical stents of 2 different pitches (6 mm and 12 mm) and wire diameters (0.52 mm and 0.6 mm) were tested in tracheas with 25% (n = 3) and 50% (n = 3) circumferentially resected cartilage rings. The percentage collapse in tracheal cross-sectional area was calculated from the recorded video contours for each experiment. RESULTS: Ex vivo tracheas compromised by single incision and 25% and 50% circumferential cartilage resection produce tracheal collapse corresponding to clinical grades of mild, moderate, and severe tracheobronchomalacia, respectively. A single anterior cartilage incision produces saber-sheath type tracheobronchomalacia, whereas 25% and 50% circumferential cartilage resection produce circumferential tracheobronchomalacia. Stent testing enabled the selection of stent design parameters such that airway collapse associated with moderate and severe tracheobronchomalacia could be reduced to conform to, but not exceed, that of intact tracheas (12-mm pitch, 0.6-mm wire diameter). CONCLUSIONS: The ex vivo trachea model is a robust platform that enables systematic study and treatment of different grades and morphologies of airway collapse and tracheobronchomalacia. It is a novel tool for optimization of stent design before advancing to in vivo animal models.

Impact of Neighborhood Socioeconomic Status on Outcomes Following First-Stage Palliation of Single Ventricle Heart Disease.

Background The impact of neighborhood socioeconomic status (SES) on outcomes following first-stage palliation of single ventricle heart disease remains incompletely characterized. Methods and Results This was a single-center, retrospective review of consecutive patients who underwent the Norwood procedure from January 1, 1997 to November 11, 2017. Outcomes of interest included in-hospital (early) mortality or transplant, postoperative hospital length-of-stay, inpatient cost, and postdischarge (late) mortality or transplant. The primary exposure was neighborhood SES, assessed using a composite score derived from 6 US census-block group measures related to wealth, income, education, and occupation. Associations between SES and outcomes were assessed using logistic regression, generalized linear, or Cox proportional hazards models, adjusting for baseline patient-related risk factors. Of 478 patients, there were 62 (13.0%) early deaths or transplants. Among 416 transplant-free survivors at hospital discharge, median postoperative hospital length-of-stay and cost were 24 (interquartile range, 15-43) days and $295 000 (interquartile range, $193 000-$563 000), respectively. There were 97 (23.3%) late deaths or transplants. On multivariable analysis, patients in the lowest SES tertile had greater risk of early mortality or transplant (odds ratio [OR], 4.3 [95% CI, 2.0-9.4; P<0.001]), had longer hospitalizations (coefficient 0.4 [95% CI, 0.2-0.5; P<0.001]), incurred higher costs (coefficient 0.5 [95% CI, 0.3-0.7; P<0.001]), and had greater risk of late mortality or transplant (hazard ratio, 2.2 [95% CI, 1.3-3.7; P=0.004]), compared with those in the highest tertile. The risk of late mortality was partially attenuated with successful completion of home monitoring programs. Conclusions Lower neighborhood SES is associated with worse transplant-free survival following the Norwood operation. This risk persists throughout the first decade of life and may be mitigated with successful completion of interstage surveillance programs.

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.

A Risk Prediction Model for Reintervention After Total Anomalous Pulmonary Venous Connection Repair.

BACKGROUND: Outcomes after total anomalous pulmonary venous connection (TAPVC) repair remain suboptimal due to recurrent pulmonary vein (PV) obstruction requiring reinterventions. We sought to develop a clinical prediction rule for PV reintervention after TAPVC repair. METHODS: Data from consecutive patients who underwent TAPVC repair at a single institution from January 1980 to January 2020 were retrospectively reviewed after Institutional Review Board approval. The primary outcome was postdischarge (late) unplanned PV surgical or transcatheter reintervention. Echocardiographic criteria were used to assess PV residual lesion severity at discharge (class 1: no residua; class 2: minor residua; class 3: major residua). Competing risk models were used to develop a weighted risk score for late reintervention. RESULTS: Of 437 patients who met entry criteria, there were 81 (18.5%) reinterventions at a median follow-up of 15.6 (interquartile range, 5.5-22.2) years. On univariable analysis, minor and major PV residua, age, single-ventricle physiology, infracardiac and mixed TAPVC, and preoperative obstruction were associated with late reintervention (all P < .05). The final risk prediction model included PV residua (class 2: subdistribution hazard ratio [SHR], 4.8; 95% CI, 2.8-8.1; P < .001; class 3: SHR, 6.4; 95% CI, 3.5-11.7; P < .001), age <1 year (SHR, 3.3; 95% CI, 1.3-8.5; P = .014), and preoperative obstruction (SHR, 1.8; 95% CI, 1.1-2.8; P = .015). A risk score comprising PV residua (class 2 or 3: 3 points), age (neonate or infant: 2 points), and obstruction (1 point) was formulated. Higher risk scores were significantly associated with worse freedom from reintervention (P < .001). CONCLUSIONS: A risk prediction model of late reintervention may guide prognostication of high-risk patients after TAPVC repair.

Influence of intraoperative residual lesions and timing of extracorporeal membrane oxygenation on outcomes following first-stage palliation of single-ventricle heart disease.

BACKGROUND: Data regarding the influence of intraoperative residual lesions on extracorporeal membrane oxygenation (ECMO) following the Norwood procedure are limited. Moreover, the significance of postoperative ECMO timing on in-hospital outcomes remains incompletely characterized. METHODS: This was a single-center, retrospective review of consecutive patients who underwent the Norwood operation from January 1997 to November 2017. Patients with at least minor residual lesions based on the intraoperative postcardiopulmonary bypass echocardiogram were identified. The association between residual lesions and postoperative ECMO was assessed with logistic regression, adjusting for age, weight, prematurity, various preoperative system-specific and procedural risk factors, shunt type, and era. Among patients receiving ECMO, associations between late ECMO (≥3 days post-Norwood) and in-hospital mortality or transplant, postoperative hospital length-of-stay, and cost of hospitalization were evaluated using logistic regression or generalized linear models with a gamma distribution and logarithmic link. RESULTS: Among 500 patients, 78 (15.6%) received ECMO postoperatively. On multivariable analysis, the presence of at least minor residual lesions (odds ratio, 4.4; 95% CI, 2.1-9.3; P < .001) was associated with postoperative ECMO. In the ECMO subpopulation, there were 44 (56.4%) deaths or transplants. Late ECMO was associated with increased risk of in-hospital mortality or transplant (adjusted odds ratio, 6.2; 95% CI, 1.5-26.0), longer postoperative hospital length of stay (regression coefficient, 0.7; 95% CI, 0.3-1.1), and greater cost (regression coefficient, 0.6; 95%, CI 0.4-0.7), versus early ECMO (all P values < .05). CONCLUSIONS: The presence of even minor intraoperative residua significantly increases the risk of ECMO following the Norwood operation. Among patients receiving ECMO postoperatively, early institution of ECMO is associated with lower mortality and resource utilization.

Systematic Mapping of Conduction Tissue Regions During Congenital Heart Surgery.

PURPOSE: Damage to the cardiac conduction system is a major risk of congenital cardiac surgery. Localization of the conduction system is commonly based on anatomic landmarks, which are variable in congenital heart diseases. We introduce a novel technique for identification of conduction tissue regions based on real-time fiberoptic confocal microscopy. DESCRIPTION: We developed a fiberoptic confocal microscopy-based technique to document conduction tissue regions and deployed it in pediatric patients undergoing repair of common congenital heart defects. The technique applies clockface schematics for intraoperative documentation of the location of conduction tissue regions. EVALUATION: We created clockface schematics for 11 patients with ventricular septal defects, 6 with tetralogy of Fallot, and 10 with atrioventricular canal defects. The approach revealed substantial variability in the location of the conduction system in hearts with congenital defects. The clockface schematics were used to create plans for subsequent surgical repair. CONCLUSIONS: The clockface schematic provides a reliable fiducial system to document and communicate variability of conduction tissue regions in the heart and applies this information for decision-making during congenital cardiac surgery.

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.

Patch augmentation of small ascending aorta during stage I procedure reduces the risk of morbidity and mortality.

OBJECTIVES: Hypoplastic left heart syndrome (HLHS) with aortic atresia (AA) patients are prone to coronary insufficiency due to a small ascending aorta. Prophylactic patch augmentation of the small ascending aorta during the stage I procedure (S1P) may reduce the risk of coronary insufficiency as marked by ventricular dysfunction, need for extracorporeal membrane oxygenator (ECMO) support or mortality. METHODS: Retrospective analysis of patients with HLHS with AA who underwent an S1P was completed. Baseline ascending aorta size, right ventricular (RV) function and outcome variables of transplant-free survival, ECMO support after the stage 1 operation and RV function at the time of the bidirectional Glenn and latest follow-up were collected. RESULTS: Between January 2010 and April 2020, 11 patients underwent prophylactic ascending aorta augmentation at the time of the S1P as a planned portion of the procedure. A total of 125 patients underwent S1P during this period as a comparison. Overall survival was 100% for the augmented group and 74% for the control group (P = 0.66). A composite end point of transplant-free survival, no post-S1P ECMO and less than moderate RV dysfunction was created. At the time of BDG, this composite end point was 100% for the augmented group and 61.8% for the control group (P = 0.008) and at most recent follow-up was 100% for the augmented group and 59.3% for control (P = 0.007). Eight patients required a rescue procedure for the clinical evidence of coronary insufficiency following S1P that included ascending aorta patch augmentation or stent placement. When comparing these rescue versus prophylactic ascending aortic augmentations, there were also differences in the composite outcome 100% for augmented and 60% for rescue (P = 0.009) and at the time of most recent follow-up 100% for augmented and 50% for rescue (P = 0.029). CONCLUSIONS: Prophylactic patch augmentation of the ascending aorta in HLHS patients with AA may reduce the risk of mortality, ECMO and reduced RV function. Patients not initially undergoing augmentation but then requiring a rescue procedure have particularly poor outcomes. Patch augmentation for smaller ascending aortic diameters should be considered and further clinical experience may help delineate aorta diameter threshold for augmentation.

Toward cardiac tissue characterization using machine learning and light-scattering spectroscopy.

SIGNIFICANCE: The non-destructive characterization of cardiac tissue composition provides essential information for both planning and evaluating the effectiveness of surgical interventions such as ablative procedures. Although several methods of tissue characterization, such as optical coherence tomography and fiber-optic confocal microscopy, show promise, many barriers exist that reduce effectiveness or prevent adoption, such as time delays in analysis, prohibitive costs, and limited scope of application. Developing a rapid, low-cost non-destructive means of characterizing cardiac tissue could improve planning, implementation, and evaluation of cardiac surgical procedures. AIM: To determine whether a new light-scattering spectroscopy (LSS) system that analyzes spectra via neural networks is capable of predicting the nuclear densities (NDs) of ventricular tissues. APPROACH: We developed an LSS system with a fiber-optics probe and applied it for measurements on cardiac tissues from an ovine model. We quantified the ND in the cardiac tissues using fluorescent labeling, confocal microscopy, and image processing. Spectra acquired from the same cardiac tissues were analyzed with spectral clustering and convolutional neural networks (CNNs) to assess the feasibility of characterizing the ND of tissue via LSS. RESULTS: Spectral clustering revealed distinct groups of spectra correlated to ranges of ND. CNNs classified three groups of spectra with low, medium, or high ND with an accuracy of 95.00 ± 11.77 % (mean and standard deviation). Our analyses revealed the sensitivity of the classification accuracy to wavelength range and subsampling of spectra. CONCLUSIONS: LSS and machine learning are capable of assessing ND in cardiac tissues. We suggest that the approach is useful for the diagnosis of cardiac diseases associated with changes of ND, such as hypertrophy and fibrosis.

Super Glenn for staged biventricular repair: impact on left ventricular growth?

OBJECTIVES: The Super Glenn procedure involves targeted increased in blood flow to left sided heart structures with fenestrated atrial septation. The objective of this study was to examine the outcomes of patients who had this procedure as a part of biventricular staging and specifically evaluate the effect on dimensions of left heart structures. METHODS: Data for patients who had this procedure between 2005 and 2019 were retrospectively identified. RESULTS: Thirty-seven patients were identified. Most common diagnosis was hypoplastic left heart syndrome in 40% (n = 15). On echocardiography, the median mitral valve z score was -2.26. On cardiac magnetic resonance imaging, median indexed left ventricular end-diastolic volume was 31.5 ml/m2 and mitral/tricuspid inflow ratio was 0.35. The median age at Super Glenn was 2.3 years (interquartile range 1.5-3.6) while median weight was 12 kg (interquartile range 9.8-14). There were no early/hospital deaths. The median intensive care unit length of stay was 4 days, and median hospital length of stay was 10 days. Median follow-up for the entire cohort was 3 years (range 15 days to 13.2 years). There was a statistically significant increase in indexed left ventricular dimensions. There were 5 deaths (14%). Three patients (8%) underwent heart transplant. Freedom from death/transplant was 79% at 5 years. Seven patients (19%) needed a reoperation. Twenty-three patients (62%) underwent biventricular conversion after a median of 11.3 months after Super Glenn. CONCLUSIONS: The Super Glenn procedure achieves consistent increase in left ventricular dimensions. This may be a useful strategy to help achieve a successful biventricular circulation in patients with borderline left ventricle. The superiority/non-inferiority of this approach over the conventional Fontan pathway is unclear.