Longitudinal Evaluation of Congenital Cardiovascular Surgical Performance and Skills Retention Using Silicone-Molded Heart Models.

Objective: Hands-on surgical training (HOST) for congenital heart surgery (CHS), utilizing silicone-molded models created from 3D-printing of patients' imaging data, was shown to improve surgical skills. However, the impact of repetition and frequency of repetition in retaining skills has not been previously investigated. We aimed to longitudinally evaluate the outcome for HOST on two example procedures of different technical difficulties with repeated attempts over a 15-week period. Methods: Five CHS trainees were prospectively recruited. Repair of coarctation of the aorta (CoA) and arterial switch operation (ASO) were selected as example procedures of relatively low and high technical difficulty. Procedural time and technical performance (using procedure-specific assessment tools by the participant, a peer-reviewer, and the proctor) were measured. Results: Coarctation repair performance scores improved after the first repetition but remained unchanged at the follow-up session. Likewise, CoA procedural time showed an early reduction but then remained stable (mean [standard deviation]: 29[14] vs 25[15] vs 23[9] min at 0, 1, and 4 weeks). Conversely, ASO performance scores improved during the first repetitions, but decreased after a longer time delay (>9 weeks). Arterial switch operation procedural time showed modest improvements across simulations but significantly reduced from the first to the last attempt: 119[20] versus 106[28] min at 0 and 15 weeks, P = .049. Conclusions: Complex procedures require multiple HOST repetitions, without excessive time delay to maintain long-term skills improvement. Conversely, a single session may be planned for simple procedures to achieve satisfactory medium-term results. Importantly, a consistent reduction in procedural times was recorded, supporting increased surgical efficiency.

iPSC-cardiomyocytes in the preclinical prediction of candidate pharmaceutical toxicity.

Many challenges remain in the preclinical evaluation, adjudication, and prioritization of novel compounds in therapeutic discovery pipelines. These obstacles are evident by the large number of candidate or lead compounds failing to reach clinical trials, significantly due to a lack of efficacy in the disease paradigm of interest and/or the presence of innate chemical toxicity. The consequential compound attrition in discovery pipelines results in added monetary and time costs, potential danger to patients, and a slowed discovery of true therapeutics. The low rate of successful translation calls for improved models that can recapitulate in vivo function in preclinical testing to ensure the removal of toxic compounds earlier in the discovery process, in particular for the assessment of cardiotoxicity, the leading cause of post-market drug withdrawal. With recent advances in the development of human Inducible pluripotent stem cell derived cardiomyocytes (iPSC-CMs), novel compounds can be assessed with better disease relevance while more accurately assessing human safety. In this review, we discuss the utility of iPSC-CMs in preclinical testing by taking advantage of the inherent ability to mimic CMs in vivo. We explore the similarities and differences in electrophysiology, calcium handling, cellular signaling, contractile machinery, and metabolism between iPSC-CMs and adult CMs as these complex coordinated functions directly relate to toxicity evaluation. We will highlight considerations when using iPSC-CMs, such as maturation protocols, to ensure a more representative phenotype of the adult human CM, and how different populations of CMs can affect results in compound testing.

Rodent Models of Dilated Cardiomyopathy and Heart Failure for Translational Investigations and Therapeutic Discovery.

Even with modern therapy, patients with heart failure only have a 50% five-year survival rate. To improve the development of new therapeutic strategies, preclinical models of disease are needed to properly emulate the human condition. Determining the most appropriate model represents the first key step for reliable and translatable experimental research. Rodent models of heart failure provide a strategic compromise between human in vivo similarity and the ability to perform a larger number of experiments and explore many therapeutic candidates. We herein review the currently available rodent models of heart failure, summarizing their physiopathological basis, the timeline of the development of ventricular failure, and their specific clinical features. In order to facilitate the future planning of investigations in the field of heart failure, a detailed overview of the advantages and possible drawbacks of each model is provided.

Deviations From Best Practice: Findings From a Certified Patient Safety Organization Remote-Verification Observational Study of Intravenous Compounding of Chemotherapeutic and Ancillary Drugs.

Background: Chemotherapeutic and immunomodulatory medications can pose a serious risk to patient and healthcare provider safety because of complex processes, cytotoxicity, and prevalent medication use. Objective: To evaluate chemotherapeutic and ancillary medication compounding in hospital pharmacies using a remote verification system, focusing on pharmaceutical deviations from best practice, compounding time, medication waste, and cost. Methods: This retrospective, blinded observational study used a remote intravenous (IV) workflow verification system to examine IV chemotherapeutic compounding errors in large hospital systems. A Patient Safety Organization securely obtained >5000 compounding records and photos from the IV workflow system. Blinded pharmacists evaluated IV chemotherapy preparations using picture slide viewers to assess any deviations from best practice. Time variables, medication waste, STAT vs non-STAT orders, and cost were also evaluated. Results: The most frequently reported deviations from best practice included medications exceeding the >10% additive volume guideline (35.9%) and inaccurate dose labels (28.3%). Time flow analyses demonstrated a substantial increase in total compounding time per vial for 1 vs 2 vials. Most medications in this analysis had an average waste ranging from 0-.36 vials. STAT orders, accounting for 38.4% of all orders, wasted more medication than non-STAT orders. Gemcitabine cost analyses showed an association for number of vials and compounding time with overall cost per dose. Conclusion: Substantial inconsistencies between workflow stations were observed-highlighting the lack of standardization across chemotherapeutics, volume of medication waste during preparation, and the need to establish improved quality controls to safeguard patient and health care provider safety.

Local Anesthetic Cardiac Toxicity Is Mediated by Cardiomyocyte Calcium Dynamics.

BACKGROUND: Long-lasting local anesthetic use for perioperative pain control is limited by possible cardiotoxicity (e.g., arrhythmias and contractile depression), potentially leading to cardiac arrest. Off-target cardiac sodium channel blockade is considered the canonical mechanism behind cardiotoxicity; however, it does not fully explain the observed toxicity variability between anesthetics. The authors hypothesize that more cardiotoxic anesthetics (e.g., bupivacaine) differentially perturb other important cardiomyocyte functions (e.g., calcium dynamics), which may be exploited to mitigate drug toxicity. METHODS: The authors investigated the effects of clinically relevant concentrations of racemic bupivacaine, levobupivacaine, or ropivacaine on human stem cell-derived cardiomyocyte tissue function. Contractility, rhythm, electromechanical coupling, field potential profile, and intracellular calcium dynamics were quantified using multielectrode arrays and optical imaging. Calcium flux differences between bupivacaine and ropivacaine were probed with pharmacologic calcium supplementation or blockade. In vitro findings were correlated in vivo using an anesthetic cardiotoxicity rat model (females; n = 5 per group). RESULTS: Bupivacaine more severely dysregulated calcium dynamics than ropivacaine in vitro (e.g., contraction calcium amplitude to 52 ± 11% and calcium-mediated repolarization duration to 122 ± 7% of ropivacaine effects, model estimate ± standard error). Calcium supplementation improved tissue contractility and restored normal beating rhythm (to 101 ± 6%, and 101 ± 26% of control, respectively) for bupivacaine-treated tissues, but not ropivacaine (e.g., contractility at 80 ± 6% of control). Similarly, calcium pretreatment mitigated anesthetic-induced arrhythmias and cardiac depression in rats, improving animal survival for bupivacaine by 8.3 ± 2.4 min, but exacerbating ropivacaine adverse effects (reduced survival by 13.8 ± 3.4 min and time to first arrhythmia by 12.0 ± 2.9 min). Calcium channel blocker nifedipine coadministration with bupivacaine, but not ropivacaine, exacerbated cardiotoxicity, supporting the role of calcium flux in differentiating toxicity. CONCLUSIONS: Our data illustrate differences in calcium dynamics between anesthetics and how calcium may mitigate bupivacaine cardiotoxicity. Moreover, our findings suggest that bupivacaine cardiotoxicity risk may be higher than for ropivacaine in a calcium deficiency context.

3D Modeling and Printing in Congenital Heart Surgery: Entering the Stage of Maturation.

3D printing allows the most realistic perception of the surgical anatomy of congenital heart diseases without the requirement of physical devices such as a computer screen or virtual headset. It is useful for surgical decision making and simulation, hands-on surgical training (HOST) and cardiovascular morphology teaching. 3D-printed models allow easy understanding of surgical morphology and preoperative surgical simulation. The most common indications for its clinical use include complex forms of double outlet right ventricle and transposition of the great arteries, anomalous systemic and pulmonary venous connections, and heterotaxy. Its utility in congenital heart surgery is indisputable, although it is hard to "scientifically" prove the impact of its use in surgery because of many confounding factors that contribute to the surgical outcome. 3D-printed models are valuable resources for morphology teaching. Educational models can be produced for almost all different variations of congenital heart diseases, and replicated in any number. HOST using 3D-printed models enables efficient education of surgeons in-training. Implementation of the HOST courses in congenital heart surgical training programs is not an option but an absolute necessity. In conclusion, 3D printing is entering the stage of maturation in its use for congenital heart surgery. It is now time for imagers and surgeons to find how to effectively utilize 3D printing and how to improve the quality of the products for improved patient outcomes and impact of education and training.

Correction: Cardiac regenerative capacity is age- and disease-dependent in childhood heart disease.

[This corrects the article DOI: 10.1371/journal.pone.0200342.].

The Incorporation of Hands-On Surgical Training in a Congenital Heart Surgery Training Curriculum.

BACKGROUND: The monthly in-house Hands-On Surgical Training (HOST) program was incorporated into the congenital heart surgery (CHS) curriculum for surgical trainees within our institution. This study evaluated whether there was an improvement and retention of technical skills throughout the curriculum via objective assessment methods. METHODS: Twelve 3-dimensional-printed surgical heart models were included into the year-long curriculum. The monthly sessions were attended by all trainees and staff surgeons. Proctors demonstrated the operation on a model, which was followed by 2 attempts by each trainee. Attempts were recorded for objective assessment. On completion of the curriculum trainees repeated 4 procedures an additional 2 times after a delay to assess skill retention. RESULTS: Twelve sessions were completed by 7 trainees within the curriculum. Objective assessments were performed in 7 sessions. Eighty-one percent of trainees' scores improved between the 2 attempts, with a mean improvement of 13% (attempt 1: HOST-CHS score of 79, attempt 2: HOST-CHS score of 89; P < .001). Similarly, 91% of procedural times improved by a mean of 25% (attempt 1, 1:22:00 [hours:minutes:seconds]; attempt 2, 1:01:21; P < .001). During individual procedure analysis, statistical significance remained in 3 of 7 procedures (P < .05). Four procedures were assessed for skill retention after a delay (2-14 months). Scores decreased by 4% in 47% of trainees during attempt 3 (attempt 2: HOST-CHS score of 94, attempt 3: HOST-CHS score of 91; P = .34) but improved in 79% during attempt 4 (attempt 3: HOST-CHS score of 91, attempt 4: HOST-CHS score of 99; P = .004), matching their previous performance. CONCLUSIONS: The monthly HOST course was successfully incorporated into a training curriculum for CHS surgeons using objective assessments to measure technical performance. Trainees demonstrated an improvement across all evaluated procedures and retained their skills when reassessed after a delay highlighting its value in CHS training.

Assessment tool validation and technical skill improvement in the simulation of the Norwood operation using three-dimensional-printed heart models.

OBJECTIVES: The hands-on surgical training course utilizes 3-dimensional (3D)-printed heart models to simulate complex congenital heart operations. This study aimed to validate a model and assessment tool in the simulation of 2 techniques of the Norwood operation and investigate whether technical performance improves following rehearsal with or without proctor presence. METHODS: Five 'experienced' and 5 'junior' surgeons performed 2 techniques of the Norwood operation on 3D-printed models of hypoplastic left heart syndrome. Performances were retrospectively assessed by 10 raters with varying experience in congenital heart surgery (CHS) (Medical Doctorate versus non-Medical Doctorate). Assessments were made with the procedure-specific Hands-On Surgical Training-CHS tool. Results were analysed for technical performance and rater consistency. Following validation, 30 surgeons (24 with proctor guidance and 6 with training videos and objective feedback only) simulated the Norwood operation twice. RESULTS: Performance scores were consistently higher for experienced surgeons and raters discriminated clearly between the experienced and junior surgeons (P ≤ 0.001). The hands-on surgical training-CHS tool showed high inter-rater (0.86) and intra-rater (0.80) reliability among all raters. Scores for both experienced and junior surgeons were highly consistent across all raters, with no statistically significant difference (P = 0.50). All surgeons successfully performed the Norwood operation. Sixty attempts were scored in total. Eighty-seven percentage (26/30) of surgeons' scores (mean: attempt 1 = 92, attempt 2 = 104) and times [mean: attempt 1 = 1:22:00, attempt 2 = 1:08:00 (h:mm:ss)] improved between the 2 attempts by 9% and 15% respectively (P ≤ 0.001). Total scores of all surgeons in the non-proctored subgroup (6) improved by 15% on average (mean: attempt 1 = 86, attempt 2 = 105, P = 0.002). CONCLUSIONS: Procedure-specific assessment tools can be developed to evaluate technical performance for complex CHS simulation and be performed reliably by non-expert raters. Rehearsal both under supervision and independently leads to technical skill improvement further supporting its value in CHS training.

Human campylobacteriosis related to cross-contamination during handling of raw chicken meat: Application of quantitative risk assessment to guide intervention scenarios analysis in the Australian context.

Quantitative Microbiological Risk Assessment (QMRA) is a methodology used to organize and analyze scientific information to both estimate the probability and severity of an adverse event as well as prioritize efforts to reduce the risk of foodborne pathogens. No QMRA efforts have been applied to Campylobacter in the Australian chicken meat sector. Hence, we present a QMRA model of human campylobacteriosis related to the occurrence of cross-contamination while handling raw chicken meat in Western Australia (WA). This work fills a gap in Campylobacter risk characterization in Australia and enables benchmarking against risk assessments undertaken in other countries. The model predicted the average probability of the occurrence of illness per serving of salad that became cross-contaminated from being handled following the handling of fresh chicken meat as 7.0 × 10-4 (90% Confidence Interval [CI] ± 4.7 × 10-5). The risk assessment model was utilized to estimate the likely impact of intervention scenarios on the predicted probability of illness (campylobacteriosis) per serving. Predicted relative risk reductions following changes in the retail prevalence of Campylobacter were proportional to the percentage desired in the reduction scenario; a target that is aiming to reduce the current baseline prevalence of Campylobacter in retail chicken by 30% is predicted to yield approximately 30% relative risk reduction. A simulated one-log reduction in the mean concentration of Campylobacter is anticipated to generate approximately 20% relative risk reductions. Relative risk reduction induced by a one-log decrease in the mean was equally achieved when the tail of the input distribution was affected-that is, by a change (one-log reduction) in the standard deviation of the baseline Campylobacter concentration. A scenario assuming a 5% point decrease in baseline probability of cross-contamination at the consumer phase would yield relative risk reductions of 14%, which is as effective as the impact of a strategic target of 10% reduction in the retail prevalence of Campylobacter. In conclusion, the present model simulates the probability of illness predicted for an average individual who consumes salad that has been cross-contaminated with Campylobacter from retail chicken meat in WA. Despite some uncertainties, this is the first attempt to utilize the QMRA approach as a scientific basis to guide risk managers toward implementing strategies to reduce the risk of human campylobacteriosis in an Australian context.

Influence of Atlantic and Pacific Sea Surface Temperatures on Heat-Related Mortality in the United States.

The frequency and magnitude of extreme summer temperature events in the United States have increased in the past few decades. Long-term exposure to extreme summer temperatures can be detrimental to human health, due to potential risks of dehydration and thermoregulation strains on the cardiovascular system, which may often lead to heat-related mortality (HRM). The summer climate of the United States is influenced by variability in Atlantic and Pacific sea surface temperatures, driven in part by Atlantic Multidecadal Oscillation (AMO) and El-Nino Southern Oscillation (ENSO), respectively. However, the influence of AMO and ENSO on HRM in the United States has not been investigated. Here the longest time series of HRM spanning the past five decades is analyzed in relation with AMO and ENSO. We find that HRM doubled in the early-1990s, coinciding with the positive phase of the AMO. Furthermore, we note a positive association between the variability in HRM and summer temperatures across all regions of the United States, with the strongest association found over the Southern United States. Therefore, this research suggests that variability in Atlantic and Pacific sea surface temperatures has both a nationwide and regional impact on HRM in the United States. Hence, by understanding variability in sea surface temperatures, the future burden of heat-attributed emergencies during extreme summer temperature events can be reduced not only for the United States, but also worldwide.

Quantitative assessment of technical performance during hands-on surgical training of the arterial switch operation using 3-dimensional printed heart models.

OBJECTIVE: Data supporting the use of hands-on simulation in congenital heart surgery are promising but primarily qualitative. This study aimed to demonstrate if there was an objective improvement in time and technical performance of the arterial switch procedure on 3-dimensional printed heart models by surgeons using a validated assessment method. METHODS: A total of 30 surgeons of varying experience performed the arterial switch procedure twice on 3-dimensional printed models with transposition of the great arteries during the Hands-on Surgical Training courses. Surgeons' performances were recorded and retrospectively assessed for both time and performance using the Hands-on Surgical Training-Congenital Heart Surgery tool, a validated procedure-specific assessment tool for the arterial switch. RESULTS: A total of 60 videos were scored. Eighty percent of surgeons (24/30) had improved from their first attempt. The mean total score of the first attempt performance compared with the second was 103 and 120, respectively, with a mean difference in score of 17 (95% confidence interval, 10-24). All surgeons were statistically significantly quicker in their second attempt. The mean time for the first attempt compared with the second was 1 hour, 28 minutes, 4 seconds and 1 hour, 5 minutes, and 45 seconds, respectively, with a mean difference of 0 hours, 22 minutes, 19 seconds (95% confidence interval, 0 hours, 15 minutes, 22 seconds to 0 hours, 25 minutes, 34 seconds). CONCLUSIONS: This is the first study to demonstrate an objective improvement in time and technical performance of the arterial switch procedure on 3-dimensional printed heart models. This supports the evidence that simulation in the form of deliberate practice with constructive, objective feedback is fundamental in the training of future congenital heart surgeons. These simulations and assessments should be incorporated to create structured, standardized training curricula within congenital heart surgery.

Development and validation of a procedure-specific assessment tool for hands-on surgical training in congenital heart surgery.

BACKGROUND: Hands-on surgical simulation has been sought to address training limitations within congenital heart surgery (CHS). However, there is a need for objective assessment methods to measure surgeons' performance to justify its global adoption. This study aimed to validate a procedure-specific assessment tool for the simulation of the arterial switch operation on 3D-printed models and to evaluate the consistency of scoring among evaluators with different levels of experience in CHS. METHODS: Five "expert" and 5 "junior" surgeons performed the arterial switch procedure on 3D-printed models with transposition of the great arteries during 2 hands-on surgical training courses. Their performance was retrospectively assessed by 9 evaluators with varying experience in CHS (staff surgeons, resident surgeons, and non-MD raters). Assessments were done using 2 assessment tools: the Hands-On Surgical Training-Congenital Heart Surgery (HOST-CHS) assessment tool and the global rating scale (GRS). RESULTS: The HOST-CHS tool showed a higher interrater and intrarater reliability compared with the GRS. Total scores for expert surgeons were highly consistent across all evaluators. Non-MD raters' total scores for junior surgeons were slightly higher than those of residents and staff evaluators. All grades of evaluator were able to discriminate between junior and expert surgeons. CONCLUSIONS: This study demonstrates the development and validation of an objective, procedure-specific assessment tool for the arterial switch operation with consistency among evaluators with different experience. There is now a platform for quantifying and accurately evaluating performance, which will be highly beneficial in training and developing the next generation of congenital heart surgeons.

Hands-On Surgical Simulation in Congenital Heart Surgery: Literature Review and Future Perspective.

Congenital heart surgery is a technically demanding specialty resulting in a prolonged training period. With the growing expectation of perfect patient outcomes, there is a need for improved training methods by implementing simulation. We assess the utilization of simulation in the training of congenital heart surgeons and discuss its future implications. A keyword-based PubMed literature search was conducted for hands-on surgical simulation in congenital heart surgery. The abstracts/titles of the search were reviewed and papers using simulation specific to congenital cardiac surgery were selected. Studies that did not include surgeons operating on the simulator, or did not incorporate assessment methods were excluded. Analysis included the problem addressed, simulator-type, methodology, assessment methods, results, benefits/limitations, and reproducibility. Five papers fulfilled our selection criteria of hands-on surgical simulation in congenital heart surgery with an assessment of the simulator or procedural performance. One simulation used animal models and 4 utilized 3D-printed models. Simulators covered either single or multiple complex procedures. All studies highlight usefulness of simulation; however, only 1 study has been replicated with >10 participants. The studies demonstrate how hands-on surgical simulation is possible within congenital heart surgery. Although primarily proof of concept studies, the next step would involve using a greater number of participants and demonstrate how repetition and deliberate practice will improve outcomes. Congenital heart surgery is one of the most technically demanding surgical specialties; therefore, we should lead the way in utilizing simulation to complement the training of our surgeons as we face the challenges ahead.

Examining the Association Between Electrodermal Activity and Problem Behavior in Severe Autism Spectrum Disorder: A Feasibility Study.

Background: Many individuals with autism spectrum disorder (ASD) engage in problem behavior, presenting significant challenges for those providing care and services for this population. Psychophysiological measures of arousal, such as electrodermal activity (EDA), may provide an early indication of subsequent problem behavior. However, variability in EDA patterns associated with behaviors may limit this predictive ability. Methods: EDA data was sampled from eight individuals with severe ASD in a naturalistic setting, while participating in educational programming in a school setting at a residential facility for severely affected individuals with developmental disabilities, to examine variability in EDA patterns. Results: An anticipatory rise in EDA only occurred 60% of the time prior to the problem behavior. Additionally, EDA after a problem behavior returned to median baseline levels only 45% of the time. Conclusions: Heterogeneity of EDA responses in those with the most severe forms of ASD will be an important consideration in future studies utilizing psychophysiological tools such as EDA to anticipate problem behavior, including the need for monitoring of return to baseline after problem behaviors. Incorporation of this consideration may lead to greater reliability of these approaches to help anticipate and manage problem behaviors.

A Baseline Quantitative Survey of Campylobacter spp. on Retail Chicken Portions and Carcasses in Metropolitan Perth, Western Australia.

INTRODUCTION: Limited baseline retail surveys have been published over the past 10 years on Campylobacter in Australian chicken meat. This study generates quantitative baseline data to assist in risk assessment and management strategies. METHODS: Raw poultry products (n = 315) were purchased for a year (2016-2017) from retail supermarkets in metropolitan Perth, Western Australia (WA). Campylobacter concentration was determined by a direct plating method in all samples, whereas in 58.7% (185/315) of the samples, testing was done using enrichment culture in conjunction with direct plating according to standard methods. RESULTS: Using direct plating, Campylobacter were recovered from 23.8% (75/315) of the samples, whereas 53.7% (100/186) of the samples were positive for Campylobacter using enrichment culture (∼1 g). Campylobacter counts revealed that 76.2% of the chicken portions and carcasses were contaminated with <1 log10 colony-forming units (CFU)/g, and 18.7% of the samples were contaminated with ≥2 log10 CFU/g. The average Campylobacter concentration among 315 tested chicken meat samples was 1.82 log10 CFU/g (±standard deviation (SD) 2.26 log10 CFU/g). The likelihood of Campylobacter recovery by direct plating from chicken products with skin on was significantly higher (odds ratio [OR] 4.4; p < 0.0001) than product forms with skin off. The highest counts of Campylobacter were associated with chicken wings (1.94 log10 CFU/g [±SD 2.26 log10 CFU/g]). There were some significant variations in Campylobacter counts based on the interaction between product forms and sourcing poultry processing establishment. CONCLUSIONS: This study provides the first published research on Campylobacter status in retail chicken meat in Australia since almost 10 years. Results from this study add to the knowledge on the assessment of microbial safety of the WA poultry chain, and can be used as an input for future development of quantitative risk assessment of Campylobacter.

Cardiac regenerative capacity is age- and disease-dependent in childhood heart disease.

OBJECTIVE: We sought to define the intrinsic stem cell capacity in pediatric heart lesions, and the effects of diagnosis and of age, in order to inform evidence-based use of potential autologous stem cell sources for regenerative medicine therapy. METHODS: Ventricular explants derived from patients with hypoplastic left heart syndrome (HLHS), tetralogy of Fallot (TF), dilated cardiomyopathy (DCM) and ventricular septal defect (VSD) were analyzed following standard in vitro culture conditions, which yielded cardiospheres (C-spheres), indicative of endogenous stem cell capacity. C-sphere counts generated per 5 mm3 tissue explant and the presence of cardiac progenitor cells were correlated to patient age, diagnosis and echocardiographic function. RESULTS: Cardiac explants from patients less than one year of age with TF and DCM robustly generated c-kit- and/or vimentin-positive cardiac mesenchymal cells (CMCs), populating spontaneously forming C-spheres. Beyond one year of age, there was a marked reduction or absence of cardiac explant-derivable cardiac stem cell content in patients with TF, VSD and DCM. Stem cell content in HLHS and DCM strongly correlated to the echocardiographic function in the corresponding ventricular chamber, with better echocardiographic function correlating to a more robust regenerative cellular content. CONCLUSIONS: We conclude that autologous cardiomyogenic potential in pediatric heart lesions is robust during the first year of life and uniformly declines thereafter. Depletion of stem cell content occurs at an earlier age in HLHS with the onset of ventricular failure in a chamber-specific pattern that correlates directly to ventricular dysfunction. These data suggest that regenerative therapies using autologous cellular sources should be implemented in the neonatal period before the potentially rapid onset of single ventricle failure in HLHS or the evolution of biventricular failure in DCM.