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.

Pathology of explanted pediatric hearts: An 11-year study. Population characteristics and implications for outcomes.

BACKGROUND: As more pediatric patients become candidates for heart transplantation (HT), understanding pathological predictors of outcome and the accuracy of the pretransplantation evaluation are important to optimize utilization of scarce donor organs and improve outcomes. The authors aimed to investigate explanted heart specimens to identify pathologic predictors that may affect cardiac allograft survival after HT. METHODS: Explanted pediatric hearts obtained over an 11-year period were analyzed to understand the patient demographics, indications for transplant, and the clinical-pathological factors. RESULTS: In this study, 149 explanted hearts, 46% congenital heart defects (CHD), were studied. CHD patients were younger and mean pulmonary artery pressure and resistance were significantly lower than in cardiomyopathy patients. Twenty-one died or underwent retransplantation (14.1%). Survival was significantly higher in the cardiomyopathy group at all follow-up intervals. There were more deaths and the 1-, 5- and 7-year survival was lower in patients ≤10 years of age at HT. Early rejection was significantly higher in CHD patients exposed to homograft tissue, but not late rejection. Mortality/retransplantation rate was significantly higher and allograft survival lower in CHD hearts with excessive fibrosis of one or both ventricles. Anatomic diagnosis at pathologic examination differed from the clinical diagnosis in eight cases. CONCLUSIONS: Survival was better for the cardiomyopathy group and patients >10 years at HT. Prior homograft use was associated with a higher prevalence of early rejection. Ventricular fibrosis (of explant) was a strong predictor of outcome in the CHD group. We presented several pathologic findings in explanted pediatric hearts.

The Connection Between Anatomical Substrate and Clinical Severity in Fetal Ebstein Anomaly.

Ebstein anomaly (EA) is a rare congenital heart defect characterized by abnormal development of the tricuspid valve (TV) and right ventricular myocardium. This study documents 2 dramatic cases of fetal EA characterized by hydrops and cardiomegaly, leading to intrauterine or early neonatal death. These clinical outcomes were associated with morphological abnormalities including severe tricuspid regurgitation, unguarded TV orifice, pulmonary atresia, and flattened right ventricular myocardium. This study highlights that these adverse anatomical features may result in unfavorable clinical outcomes in fetal EA. While timely identification of such features by prenatal ultrasound is crucial for providing accurate prognostic stratification and guiding treatment decisions, fetopsy may be necessary to discern EA among the spectrum of right-heart anomalies.

A modifiable valve-sparing pediatric cardiac dissection technique promotes specimen longevity and optimizes advanced image analysis postpathological examination.

This paper illustrates a valve-sparing cardiac dissection technique that keeps the atrioventricular and semilunar valves and other important cardiac structures intact. The technique minimizes disruption in heart specimens, so they remain suitable for teaching, demonstration, and further research. When performed following the perfusion-distension method of fixation, as our group previously described, this technique could optimize the preservation of heart specimens for teaching and digital archiving postdissection.

Double Aortic Arch with Atresia of the Left Aortic Arch Proximal to the Left Common Carotid Artery: First Report of Documentation by Surgical Observation.

Double aortic arch associated with atresia of the left arch proximal to the left common carotid artery has been considered a theoretical possibility. To our knowledge, we report the first patient with this anatomy confirmed by surgical observation.

Tricuspid Valve Blood Cysts Mimicking Thrombus or Vegetation on Echocardiogram in a Neonate.

A 2-month-old male infant, born premature with a birth weight of 865 g, was found to have a tricuspid valve mass mimicking thrombus and vegetation by echocardiogram on the fourth day of life. The patient was treated with antibiotics and anticoagulation with no change in the size of the mass on serial follow-up echocardiography. The patient died of severe pulmonary vein stenosis and complex neurological disability. Postmortem cardiac examination revealed numerous cardiac blood cysts with two dominant ones (1.6 and 1.5 mm) on the septal leaflet of the tricuspid valve, which based on the location and position corresponded to the suspected vegetation and thrombus on imaging. Cardiac blood cysts on valve leaflets are a common incidental finding during autopsy within the first 6 months of life; however, they are rarely detected on imaging because of their minute size, often < 0.5 mm. In this case, the sizable blood cysts were thought to represent thrombus or vegetation on echocardiogram, which influenced the patient management.

Biventricular non-compaction cardiomyopathy and tricuspid hypoplasia in a novel non-POU domain-containing octamer-binding gene variant.

A maternally inherited novel pathogenic non-POU domain-containing octamer-binding gene variant c.767G>T, p.R256I [NM_001145408], manifested in a male infant as dilated cardiomyopathy with severe left ventricular dysfunction and dilation, biventricular non-compaction, tricuspid hypoplasia, and hydrocephaly. To the best of our knowledge, no previous non-POU domain-containing octamer-binding gene variants with biventricular non-compaction have been associated with tricuspid valve hypoplasia. Hence, this case introduces a new pathogenic variant observed in the non-POU domain-containing octamer-binding gene and adds to the range of cardiac phenotypes identified in non-POU domain-containing octamer-binding gene variants.

Nomenclature for Pediatric and Congenital Cardiac Care: Unification of Clinical and Administrative Nomenclature - The 2021 International Paediatric and Congenital Cardiac Code (IPCCC) and the Eleventh Revision of the International Classification of Diseases (ICD-11).

Substantial progress has been made in the standardization of nomenclature for paediatric and congenital cardiac care. In 1936, Maude Abbott published her Atlas of Congenital Cardiac Disease, which was the first formal attempt to classify congenital heart disease. The International Paediatric and Congenital Cardiac Code (IPCCC) is now utilized worldwide and has most recently become the paediatric and congenital cardiac component of the Eleventh Revision of the International Classification of Diseases (ICD-11). The most recent publication of the IPCCC was in 2017. This manuscript provides an updated 2021 version of the IPCCC.The International Society for Nomenclature of Paediatric and Congenital Heart Disease (ISNPCHD), in collaboration with the World Health Organization (WHO), developed the paediatric and congenital cardiac nomenclature that is now within the eleventh version of the International Classification of Diseases (ICD-11). This unification of IPCCC and ICD-11 is the IPCCC ICD-11 Nomenclature and is the first time that the clinical nomenclature for paediatric and congenital cardiac care and the administrative nomenclature for paediatric and congenital cardiac care are harmonized. The resultant congenital cardiac component of ICD-11 was increased from 29 congenital cardiac codes in ICD-9 and 73 congenital cardiac codes in ICD-10 to 318 codes submitted by ISNPCHD through 2018 for incorporation into ICD-11. After these 318 terms were incorporated into ICD-11 in 2018, the WHO ICD-11 team added an additional 49 terms, some of which are acceptable legacy terms from ICD-10, while others provide greater granularity than the ISNPCHD thought was originally acceptable. Thus, the total number of paediatric and congenital cardiac terms in ICD-11 is 367. In this manuscript, we describe and review the terminology, hierarchy, and definitions of the IPCCC ICD-11 Nomenclature. This article, therefore, presents a global system of nomenclature for paediatric and congenital cardiac care that unifies clinical and administrative nomenclature.The members of ISNPCHD realize that the nomenclature published in this manuscript will continue to evolve. The version of the IPCCC that was published in 2017 has evolved and changed, and it is now replaced by this 2021 version. In the future, ISNPCHD will again publish updated versions of IPCCC, as IPCCC continues to evolve.

Myofiber organization in the failing systemic right ventricle.

BACKGROUND: The right ventricle (RV) often fails when functioning as the systemic ventricle, but the cause is not understood. We tested the hypothesis that myofiber organization is abnormal in the failing systemic right ventricle. METHODS: We used diffusion-weighted cardiovascular magnetic resonance imaging to examine 3 failing hearts explanted from young patients with a systemic RV and one structurally normal heart with postnatally acquired RV hypertrophy for comparison. Diffusion compartment imaging was computed to separate the free diffusive component representing free water from an anisotropic component characterizing the orientation and diffusion characteristics of myofibers. The orientation of each anisotropic compartment was displayed in glyph format and used for qualitative description of myofibers and for construction of tractograms. The helix angle was calculated across the ventricular walls in 5 locations and displayed graphically. Scalar parameters (fractional anisotropy and mean diffusivity) were compared among specimens. RESULTS: The hypertrophied systemic RV has an inner layer, comprising about 2/3 of the wall, composed of hypertrophied trabeculae and an epicardial layer of circumferential myofibers. Myofibers within smaller trabeculae are aligned and organized with parallel fibers while larger, composite bundles show marked disarray, largely between component trabeculae. We observed a narrow range of helix angles in the outer, compact part of the wall consistent with aligned, approximately circumferential fibers. However, there was marked variation of helix angle in the inner, trabecular part of the wall consistent with marked variation in fiber orientation. The apical whorl was disrupted or incomplete and we observed myocardial whorls or vortices at other locations. Fractional anisotropy was lower in abnormal hearts while mean diffusivity was more variable, being higher in 2 but lower in 1 heart, compared to the structurally normal heart. CONCLUSIONS: Myofiber organization is abnormal in the failing systemic RV and might be an important substrate for heart failure and arrhythmia. It is unclear if myofiber disorganization is due to hemodynamic factors, developmental problems, or both.

Chondroid and Osseous Metaplasia of the Central Fibrous Body in Adolescent Hearts with Mutations in TNNI3 and TNNT2 genes.

The histological spectrum of the central fibrous body (CFB) of the heart, particularly in humans, is not fully characterized. Herein, we describe the presence of cartilage and bone within the CFB of 2 explanted heart specimens from patients with known mutation-driven cardiomyopathy involving the TNNI3 and TNNT2 genes, review the existing literature on the identified variants particularly TNNI3 (p.Asn185Thrfs*14) and TNNT2 (p.Arg141Trp), and provide insights into the plausible nature of such histopathological observation based on animal studies and the few reported cases in humans.

Systemic Ventricular Dysfunction Between Stage One and Stage Two Palliation.

Infants with a single ventricle can develop systemic ventricular dysfunction (SVD) after stage 1 operation, but available information is sparse. We reviewed our patients having Norwood, Sano, or hybrid procedures to better understand this problem. We conducted a retrospective, case-controlled cohort study of 267 patients having stage1 operation, examining outcomes between stages 1 and 2 (survival and subsequent cardiac surgeries), predictor variables, and histology of hearts explanted at transplantation. SVD developed in 32 (12%) patients and resolved in 13 (41%); mean age of onset was 3.0 ± 1.63 months; median = 2.79. SVD was not associated with cardiac anatomy, type of stage 1 procedure, weight, coronary abnormality, or atrioventricular valve regurgitation. The mean age of resolution = 12.1 ± 9.6 months; median = 6.3, and resolution may have been more likely with a systemic LV than RV (p = 0.067). Outcomes for the entire SVD group were less favorable than for those without, but patients with resolution of SVD had outcomes at least as good those without SVD. Myocardial histology (n = 4) suggested chronic ischemia. The risk of SVD after stage 1, while low, may be a fundamental feature of this patient population. SVD occurs with either a systemic RV or LV, although patients with a systemic LV may be more likely to have resolution than those with an RV. We identified no predictor variables, but histologic findings suggest chronic ischemia may be involved. Given the low incidence of SVD, multi-center studies will be required to better define predictors of onset and resolution.

A Pediatric Cardiology Fellowship Boot Camp improves trainee confidence.

Introduction New paediatric cardiology trainees are required to rapidly assimilate knowledge and gain clinical skills to which they have limited or no exposure during residency. The Pediatric Cardiology Fellowship Boot Camp (PCBC) at Boston Children's Hospital was designed to provide incoming fellows with an intensive exposure to congenital cardiac pathology and a broad overview of major areas of paediatric cardiology practice. METHODS: The PCBC curriculum was designed by core faculty in cardiac pathology, echocardiography, electrophysiology, interventional cardiology, exercise physiology, and cardiac intensive care. Individual faculty contributed learning objectives, which were refined by fellowship directors and used to build a programme of didactics, hands-on/simulation-based activities, and self-guided learning opportunities. RESULTS: A total of 16 incoming fellows participated in the 4-week boot camp, with no concurrent clinical responsibilities, over 2 years. On the basis of pre- and post-PCBC surveys, 80% of trainees strongly agreed that they felt more prepared for clinical responsibilities, and a similar percentage felt that PCBC should be offered to future incoming fellows. Fellows showed significant increase in their confidence in all specific knowledge and skills related to the learning objectives. Fellows rated hands-on learning experiences and simulation-based exercises most highly. CONCLUSIONS: We describe a novel 4-week-long boot camp designed to expose incoming paediatric cardiology fellows to the broad spectrum of knowledge and skills required for the practice of paediatric cardiology. The experience increased trainee confidence and sense of preparedness to begin fellowship-related responsibilities. Given that highly interactive activities were rated most highly, boot camps in paediatric cardiology should strongly emphasise these elements.

Accelerated degeneration of a bovine pericardial bioprosthetic aortic valve in children and young adults.

BACKGROUND: Experience with aortic valve replacement (AVR) with current-generation pericardial bioprostheses in young patients is limited. The death of a child with accelerated bioprosthetic aortic stenosis prompted enhanced surveillance of all such patients at our institution. METHODS AND RESULTS: We reviewed records of 27 patients who had undergone AVR (median follow-up, 13.7 months) with a bovine pericardial bioprosthesis at ≤30 years of age. In the Mitroflow LXA valve group (n=15), freedom from valve failure was 100% at 1 year, 53% (95% confidence interval, 12-82) at 2 years, and 18% (95% confidence interval, 1-53) at 3 years. No Magna/Magna Ease valves (n=12) failed by 3 years. Among valve failure patients, median age at AVR was 12 years (range, 10-21 years). Life-threatening prosthetic aortic stenosis was detected at a median of 6 months after prior echocardiograms showing mild or less gradients. Patients with Mitroflow LXA compared with Magna/Magna Ease valves were smaller (median body surface area, 1.42 versus 1.93 m(2); P=0.002) and younger (median age, 13.0 versus 20.9 years; P=0.02) at AVR. Pathology demonstrated diffuse intrinsic leaflet calcification, not associated with inflammation or infection, and virtually immobile leaflets in closed position. CONCLUSIONS: Young patients undergoing AVR with Mitroflow LXA pericardial valves are at high risk for rapid progression from mild or less to severe aortic stenosis over months, highlighting their need for heightened echocardiographic surveillance and suggesting that this aortic bioprosthesis should not be implanted in the young. Current data are insufficient to assess the safety of AVR with other pericardial bioprostheses in children and the youngest adults.

Iatrogenic aortopulmonary communications after transcatheter interventions on the right ventricular outflow tract or pulmonary artery: Pathophysiologic, diagnostic, and management considerations.

OBJECTIVES: To investigate the spectrum, etiology, and management of traumatic aortopulmonary (AP) communications after transcatheter interventions on the pulmonary circulation. BACKGROUND: An iatrogenic AP communication is an unusual complication after balloon pulmonary artery (PA) angioplasty or stenting, or transcatheter pulmonary valve replacement (TPVR). However, with the increasing application of transcatheter therapies for postoperative PA stenosis and right ventricular outflow tract (RVOT) dysfunction, including percutaneous pulmonary valve replacement, consideration of the etiology, diagnosis, and management of this problem is important for interventional cardiologists performing such procedures. METHODS AND RESULTS: We present three new cases, as well as gross anatomy and histopathology data, related to AP communications after PA interventions. We also review the literature relevant to this topic. Including these new cases, there have been 18 reported cases of iatrogenic AP communication after transcatheter interventions on the PAs or RVOT, primarily patients with transposition of the great arteries who underwent PA angioplasty after an arterial switch operation, or after TPVR in patients who had undergone a Ross procedure. The likely cause of such defects is PA trauma plus distortion of the neo-aortic anastomosis resulting from angioplasty or stenting of the RVOT or central PAs, with subsequent dissection through the extravascular connective tissue and into the closely adjacent vessel through the devitalized tissue at the anastomosis. CONCLUSIONS: Cardiologists performing PA or RVOT interventions should be aware of the possibility of a traumatic AP communication and consider this diagnosis when confronted with suggestive signs and symptoms.

Postmortem imaging in congenital heart disease: preliminary experience.

BACKGROUND: Despite the importance of the autopsy for quality improvement, autopsy rates have declined dramatically in recent decades due to poor acceptance by families and physicians and high costs to institutions. PURPOSE: To compare postmortem imaging (PMI) with autopsy in patients with congenital heart defects to see if PMI could substitute in some or all cases and to compare costs of the two methods. MATERIAL AND METHODS: Ten patients with congenital heart disease dying in hospital during the study period in whom an autopsy was planned underwent PMI using postmortem magnetic resonance imaging (PMMRI) (6 patients) and postmortem computed tomographic angiography (PMCTA) (10 patients) with permission of the family. Four patients were excluded from PMMR because of metal ECMO cannulas. PMI was interpreted before autopsy using an organ system checklist and results compared to autopsy. The costs of each method were tracked. RESULTS: When both PMMR and PMCTA were performed the PMI findings corresponded closely with autopsy. PMI correctly diagnosed the principal heart defects in all six cases and correctly imaged central vessels, heart valves and chambers, brain, abdominal organs, and bone. Weak points were visualization of the coronary arteries and distinguishing postmortem pulmonary atelectasis from lung pathology. The cause of death by PMI matched autopsy findings in 5/6 cases in which both PMMR and PMCTA were performed and was incomplete in the other five cases. The cost of PMI was about 15% lower than the cost of autopsy. CONCLUSION: PMI provided most gross anatomic cardiac diagnoses available by autopsy in our series of patients with congenital heart defects and the cost appears to be lower.

Postmortem imaging of antemortem myocardial ischaemia.

OBJECTIVES: To determine the minimum survival time for detection of antemortem myocardial ischaemia with postmortem imaging (PMI) techniques. METHODS: Nine pigs underwent ligation of the left anterior descending (LAD) (8) and/or right coronary artery (RCA) branch (4), and were killed 30 min-6 h after ligation. PMI (MRI and CT angiography) was performed 2-55 h after euthanasia. Signal intensity of myocardial segments was measured. The hearts were removed, the coronary arteries injected to mark perfused segments, and sections submitted for histology. RESULTS: MRI T2-weighted sequences showed the ischaemic area as hyperintense in 4/4 LAD ligations with ≥4 h of ischaemia but in 0/4 with <4 h. Histological evidence of ischaemia was present in 4/4 animals after 4 h. Right ventricular ischaemic myocardium was visible on MRI T2-weighted sequences after 6 h of ischaemia in one animal. CT angiography showed the occluded coronary artery in all cases. CONCLUSIONS: Ischaemic lesions of the left ventricle, but not of the right, at least 4 h old can be detected as hyperintense areas on T2-weighted postmortem MRI. This technique is most sensitive in the first 24 h after death. Other sequences did not enhance detection. KEY POINTS: • Left ventricular myocardial ischaemia/infarction can be demonstrated by postmortem imaging (PMI). • Ischaemia/infarction is better detected if survival time is at least 4 h. • Right ventricular ischaemia/infarction is not reliably detected by PMI. • Computed tomography angiography can demonstrate arterial occlusion.

QRS duration and QRS fractionation on surface electrocardiogram are markers of right ventricular dysfunction and atrialization in patients with Ebstein anomaly.

BACKGROUND: Ebstein anomaly is a rare and heterogeneous congenital heart defect affecting the tricuspid valve and right ventricular (RV) myocardium. Few studies have analysed the electrocardiographic features of Ebstein anomaly and none has addressed correlations with disease severity. METHODS: Patients with Ebstein anomaly who had undergone electrocardiography and cardiac magnetic resonance (CMR) within 6 weeks between 2001 and 2009 were included. Exclusion criteria were: associated congenital cardiac defect, previous RV myoplasty and/or reduction surgery, class I anti-arrhythmic drug therapy, and paced/pre-excited QRS. Standard electrocardiogram (ECG) findings were correlated with CMR-based RV measures and clinical profile. RESULTS: The mean age of the 63 study patients was 22 ± 13 years. An RV conduction delay (rsR' pattern in right precordial leads) was present in 45 patients (71%). The QRS duration correlated with anatomic RV diastolic volume (r = +0.56, P < 0.0001) and inversely with RV ejection fraction (EF; r = -0.62, P < 0.0001). The presence of QRS fractionation predicted greater atrialized RV volume (80 ± 31 vs. 45 ± 37 mL/m(2), P < 0.001). Normal QRS duration was associated with smaller anatomic RV diastolic volume (150 ± 57 vs. 256 ± 100 mL/m(2); P < 0.0001), higher RV EF (48 ± 6 vs. 34 ± 14%; P < 0.0001), higher oxygen consumption (VO(2)) at cardiopulmonary exercise (25.8 vs. 21.8 mL/kg/min, P = 0.05) and lower incidence of oxygen desaturation with exercise (25 vs. 65%, P = 0.02). CONCLUSION: Delayed and prolonged depolarization of the RV is common in patients with Ebstein anomaly. The QRS duration is a marker of RV enlargement and dysfunction. QRS fractionation is associated with a greater atrialized RV volume. A preserved surface ECG identifies a subset of patients with Ebstein anomaly with mild morphological and functional abnormalities and better clinical profile.

Ventricular mechanics in patients with aortic valve disease: longitudinal, radial, and circumferential components.

BACKGROUND: Reduced long-axis shortening despite enhanced global function has been reported in aortic stenosis. We sought to improve the understanding of this phenomenon using multi-dimensional strain analysis in conjunction with the evaluation of left ventricular rotation and twist - ventricular torsion - using tissue Doppler techniques. METHODS: A total of 57 patients with variable severity of aortic stenosis, aortic regurgitation, or mixed aortic valve disease, subdivided into six groups, were studied. Ventricular morphology was assessed using long-axis/short-axis and mass/volume ratios, afterload using end-systolic meridional wall stress, and global performance using ejection fraction. The circumferential and longitudinal strain was measured from two-dimensional images, and left ventricular rotation and twist were estimated as the difference in rotation between the base and apex of the ventricle. RESULTS: Aortic stenosis was associated with higher mass/volume, ejection fraction, circumferential strain and left ventricular rotation and twist, significantly lower end-systolic wall stress, and a trend towards lower longitudinal strain compared with normal. Myocardial mechanics in aortic regurgitation were normal despite ventricular dilation. Mixed aortic valve disease showed findings similar to aortic stenosis. Left ventricular rotation and twist correlated with midwall circumferential strain (r = 0.62 and p < 0.0001), endocardial circumferential strain (r = 0.61 and p < 0.0001), and end-systolic wall stress (r = 0.48 and p < 0.0001), but not with longitudinal strain (r = 0.18 and p > 0.05). CONCLUSIONS: Myocardial mechanics are normal in patients with aortic regurgitation, independent of abnormalities in cardiac geometry. Conversely, in aortic stenosis and mixed aortic valve disease, significant alterations in the patterns of fibre shortening are found. The effects of stenosis on cardiac function seem to dominate the effect of ventricular remodelling.

High-resolution three-dimensional atlas of congenital heart defects based on micro-CT images of human postmortem wax-infiltrated heart specimens.

INTRODUCTION: Postmortem heart specimens are essential for education and research on the anatomy, morphology, and pathology of congenital heart defects. However, such specimens are rarely obtained these days, and the specimens stored in formalin are inexorably deteriorating. This study aimed to develop methods to archive three-dimensional data of rare human heart specimens and to publish the data. METHODS: All wax-infiltrated human postmortem heart specimens stored in the Cardiac Registry, Boston Children's Hospital were scanned using microfocus computed tomography (X-Tek HMXST225, Nikon Metrology, Inc.), and reproduced using a three-dimensional printer (Form 3B, Formlabs Inc.). The digital models were published as an interactive three-dimensional online atlas. The resolution of the three-dimensional data was evaluated. RESULTS: The primary diagnoses in the 88 specimens included in the study include normal cardiac anatomy (11 cases), transposition of the great arteries {S,D,D} (11 cases), ventricular septal defect (10 cases), double-outlet right ventricle (9 cases), hypoplastic left heart syndrome (9 cases), and common atrioventricular canal (7 cases). Twenty-five cases (28%) underwent previous surgical or percutaneous interventions to the heart, including Mustard procedure (1 case), Senning procedure (2 cases, one was performed on a postmortem heart specimen). The median voxel size of the three-dimensional data was 40.5 um (IQR, 32.8-64.2). All intracardiac structures were precisely reproduced as digital and physical three-dimensional models. CONCLUSIONS: The methods and resultant models were considered useful for archiving and furthering the utilization of these invaluable specimens. The atlas is available at https://www.sketchfab.com/heartmodels/collections.