Noncompaction in the fetus and neonate: an autopsy study

Sudden unexpected intrapartum death and left ventricular noncompaction involving the right ventricle

Left ventricular noncompaction (LVNC), involving mainly the right ventricle, is a rare form of congenital heart disorder characterized by a developmental arrest in myocardial compaction, resulting in a spongy appearance of the myocardium, mainly of the right ventricle, rarely detected in fetuses. We report the case of a female fetus with a gestational age of 41+4 weeks who came to our attention for intrapartum sudden unexpected death, resulting in stillbirth. The ventricular walls, particularly the right ventricular wall, appeared thick, hypertrabeculated and spongy, leading to the diagnosis of LVNC involving mainly the right ventricle. The atrioventricular node and His bundle presented areas of fetal dispersion and resorptive degeneration; islands of conduction tissue were detected in the central fibrous body. Arcuate nucleus of the brainstem showed bilateral severe hypoplasia. The right bundle branch was hypoplastic. The final cause of death was an electrical conduction disfunction in an LVNC involving mainly the right ventricle. To the best of our knowledge, the herein described case is the first reported observation of sudden intrapartum death from LVNC involving mainly the right ventricle well documented post-mortem with cardiac conduction and brainstem studies. Our findings confirm the need of an accurate post-mortem examination including the study of the cardiac conduction system on serial section in every case of sudden unexpected fetal death, although there are no universally recognized guidelines.

Postmortem histological freeze-thaw artifacts: a case report of a frozen infant and literature review

Freezing and thawing have the potential to alter the gross and histologic appearance of tissues, causing damage to individual cells and disrupting the overall architecture. In forensic investigations, freezing and thawing can play a crucial role in cases of unknown cause of death. Perpetrators may use freezing preservation to conceal the body or obscure the time of death. Freezing can also occur naturally when a body is exposed to the elements, sometimes even leading to death itself. We present a case report involving an autopsy performed on an infant, who died of natural causes, after undergoing freezing and thawing. The objective of this study was to identify and discuss the histological artifacts observed in different tissues as a result of the freeze-thaw process. Histologically, the infant's tissues exhibited the most common features described in the literature. Ice crystal artifacts, characterized by expansion of the extracellular space and tissue clefts, were found in the heart, brain, liver, lungs, and kidneys. On the contrary, adipose tissue was not affected, likely due to the scarcity of water. Freeze-thaw artifacts should be taken into account whether a body is known to have been frozen or to add further data if found already defrosted.

Excessive Trabeculation of the Left Ventricle: JACC: Cardiovascular Imaging Expert Panel Paper

Excessive trabeculation, often referred to as "noncompacted" myocardium, has been described at all ages, from the fetus to the adult. Current evidence for myocardial development, however, does not support the formation of compact myocardium from noncompacted myocardium, nor the arrest of this process to result in so-called noncompaction. Excessive trabeculation is frequently observed by imaging studies in healthy individuals, as well as in association with pregnancy, athletic activity, and with cardiac diseases of inherited, acquired, developmental, or congenital origins. Adults with incidentally noted excessive trabeculation frequently require no further follow-up based on trabecular pattern alone. Patients with cardiomyopathy and excessive trabeculation are managed by cardiovascular symptoms rather than the trabecular pattern. To date, the prognostic role of excessive trabeculation in adults has not been shown to be independent of other myocardial disease. In neonates and children with excessive trabeculation and normal or abnormal function, clinical caution seems warranted because of the reported association with genetic and neuromuscular disorders. This report summarizes the evidence concerning the etiology, pathophysiology, and clinical relevance of excessive trabeculation. Gaps in current knowledge of the clinical relevance of excessive trabeculation are indicated, with priorities suggested for future research and improved diagnosis in adults and children.

PKN2 deficiency leads both to prenatal congenital cardiomyopathy and defective angiotensin II stress responses

The protein kinase PKN2 is required for embryonic development and PKN2 knockout mice die as a result of failure in the expansion of mesoderm, cardiac development and neural tube closure. In the adult, cardiomyocyte PKN2 and PKN1 (in combination) are required for cardiac adaptation to pressure-overload. The specific role of PKN2 in contractile cardiomyocytes during development and its role in the adult heart remain to be fully established. We used mice with cardiomyocyte-directed knockout of PKN2 or global PKN2 haploinsufficiency to assess cardiac development and function using high resolution episcopic microscopy, MRI, micro-CT and echocardiography. Biochemical and histological changes were also assessed. Cardiomyocyte-directed PKN2 knockout embryos displayed striking abnormalities in the compact myocardium, with frequent myocardial clefts and diverticula, ventricular septal defects and abnormal heart shape. The sub-Mendelian homozygous knockout survivors developed cardiac failure. RNASeq data showed up-regulation of PKN2 in patients with dilated cardiomyopathy, suggesting an involvement in adult heart disease. Given the rarity of homozygous survivors with cardiomyocyte-specific deletion of PKN2, the requirement for PKN2 in adult mice was explored using the constitutive heterozygous PKN2 knockout. Cardiac hypertrophy resulting from hypertension induced by angiotensin II was reduced in these haploinsufficient PKN2 mice relative to wild-type littermates, with suppression of cardiomyocyte hypertrophy and cardiac fibrosis. It is concluded that cardiomyocyte PKN2 is essential for heart development and the formation of compact myocardium and is also required for cardiac hypertrophy in hypertension. Thus, PKN signalling may offer therapeutic options for managing congenital and adult heart diseases.

Clinical Characteristics and Prognosis of Fetal Left Ventricular Noncompaction in Japan

BACKGROUND

Left ventricular noncompaction (LVNC) is morphologically characterized by numerous prominent trabeculations and a severely thickened, two-layered myocardium. The fetal onset of LVNC has rarely been described.

METHODS AND RESULTS

We conducted nationwide retrospective surveys on fetal cardiomyopathy (CM) in Japan from 2010 to 2016, from which 38 fetal patients with CM were enrolled, including 16 patients with LVNC. The rate of diagnostic concordance was 56.3% between fetal and postnatal visits in LVNC patients. The increase in the ratio of noncompacted to compacted (N/C) myocardium was time-dependent throughout the fetal period till birth (LV lateral: 1.6±0.1 to 2.8±0.2; LV apex: 2.0±0.1 to 3.2±0.2). Of all fetuses, 16 (42.1%) died or underwent heart transplantation (HT), with 3 intrauterine deaths. Lower fetal cardiovascular profile score (odds ratio, 26.9; P=0.0266) was a risk factor for death or HT. N/C ratio ≥1.6 at the apex at the first visit was a significant predictor of LVNC (odds ratio, 47.8; P=0.0113).

CONCLUSIONS

This is the first study to reveal the etiology of fetal CM based on results from a nationwide survey in Japan, highlighting the difficulty of diagnosing LVNC in fetal patients. To better understand and manage fetal CM, novel diagnostic criteria of LVNC in fetus should be established.

Higher spatial resolution improves the interpretation of the extent of ventricular trabeculation

The ventricular walls of the human heart comprise an outer compact layer and an inner trabecular layer. In the context of an increased pre-test probability, diagnosis left ventricular noncompaction cardiomyopathy is given when the left ventricle is excessively trabeculated in volume (trabecular vol >25% of total LV wall volume) or thickness (trabecular/compact (T/C) >2.3). Here, we investigated whether higher spatial resolution affects the detection of trabeculation and thus the assessment of normal and excessively trabeculated wall morphology. First, we screened left ventricles in 1112 post-natal autopsy hearts. We identified five excessively trabeculated hearts and this low prevalence of excessive trabeculation is in agreement with pathology reports but contrasts the prevalence of approximately 10% of the population found by in vivo non-invasive imaging. Using macroscopy, histology and low- and high-resolution MRI, the five excessively trabeculated hearts were compared with six normal hearts and seven abnormally trabeculated and excessive trabeculation-negative hearts. Some abnormally trabeculated hearts could be considered excessively trabeculated macroscopically because of a trabecular outflow or an excessive number of trabeculations, but they were excessive trabeculation-negative when assessed with MRI-based measurements (T/C <2.3 and vol <25%). The number of detected trabeculations and T/C ratio were positively correlated with higher spatial resolution. Using measurements on high resolution MRI and with histological validation, we could not replicate the correlation between trabeculations of the left and right ventricle that has been previously reported. In conclusion, higher spatial resolution may affect the sensitivity of diagnostic measurements and in addition could allow for novel measurements such as counting of trabeculations.

Genetics and Clinical Features of Noncompaction Cardiomyopathy in the Fetal Population

Objectives: Noncompaction Cardiomyopathy (NCCM) has been classified as primary genetic cardiomyopathy and has gained increasing clinical awareness; however, little is known about NCCM in the fetal population. We aimed to investigate the clinical characteristics and genetic spectrum of a fetal population with NCCM. Methods: We retrospectively reviewed all fetuses with a prenatal diagnosis of NCCM at a single center between October 2010 and December 2019. These cases were investigated for gestational age at diagnosis, gender, left or biventricular involvement, associated cardiac phenotypes, outcomes, and genetic testing data. Results: We identified 37 fetuses with NCCM out of 49,898 fetuses, indicating that the incidence of NCCM in the fetal population was 0.07%. Of the 37 fetuses, 26 were male, ten were female and one was of unknown gender. NCCM involvement biventricle is the most common (n = 16, 43%), followed by confined to the left ventricle (n = 14, 38%). Nineteen (51%) had additional congenital heart defects, with right-sided lesions being the most common (n = 14, 74%), followed by ventricular septal defects (n = 10, 53%). Hydrops fetalis was present in 12 cases (32%), of which four were atypical (pericardial effusion only). Sequencing analysis was performed at autopsy (n = 19) or postnatally (n = 1) on 20 fetuses. Of the 20 fetuses undergoing copy number variation sequencing and whole-exome sequencing, nine (47%) had positive genetic results, including one with a pathogenic copy number variant and eight with pathogenic/likely pathogenic variants. Non-sarcomere gene mutations accounted for the vast majority (n = 7). In contrast, sarcomere gene mutations occurred in only one case (TPM1), and no mutations were identified in the three most common sarcomere genes (MYH7, TTN, and MYBPC3) of pediatric and adult patients. Pathogenic/likely pathogenic variants were significantly more frequent in fetuses with congenital heart defects than those without congenital heart defects. Conclusions: Our data demonstrate that fetal NCCM is a unique entity. Compared with pediatric and adult NCCM, fetal NCCM is more prone to biventricle involvement, more likely to be complicated with congenital heart defects, and has a distinct genetic spectrum.

Reduced Systolic Function and Not Genetic Variants Determine Outcome in Pediatric and Adult Left Ventricular Noncompaction Cardiomyopathy

Background: Left ventricular noncompaction cardiomyopathy (LVNC CMP) is a genetic cardiomyopathy. Genotype-phenotype correlation and clinical outcome of genetic variants in pediatric and adult LVNC CMP patients are still unclear. Methods: The retrospective multicenter study was conducted in unrelated index patients with LVNC CMP, diagnosed between the years 1987 and 2017, and all available family members. All index patients underwent next-generation sequencing for genetic variants in 174 target genes using the Illumina TruSight Cardio Sequencing Panel. Major adverse cardiac events (MACE) included mechanical circulatory support, heart transplantation, survivor of cardiac death, and/or all-cause death as combined endpoint. Results: Study population included 149 LVNC CMP patients with a median age of 27.8 (9.2-44.8) years at diagnosis; 58% of them were symptomatic, 18% suffered from non-sustained and sustained arrhythmias, and 17% had an implantable cardioverter defibrillator (ICD) implanted. 55/137 patients (40%) were ≤ 18 years at diagnosis. A total of 134 variants were identified in 87/113 (77%) index patients. 93 variants were classified as variant of unknown significance (VUS), 24 as likely pathogenic and 15 as pathogenic. The genetic yield of (likely) pathogenic variants was 35/113 (31%) index patients. Variants occurred most frequently in MYH7 (n=19), TTN (n = 10) and MYBPC3 (n = 8). Altogether, sarcomere gene variants constituted 42.5% (n = 57) of all variants. The presence or absence of (likely) pathogenic variants or variants in specific genes did not allow risk stratification for MACE. Reduced left ventricular (LV) systolic function and increased left ventricular end-diastolic diameter (LVEDD) were risk factors for event-free survival in the Kaplan-Meier analysis. Through multivariate analysis we identified reduced LV systolic function as the main risk factor for MACE. Patients with reduced LV systolic function were at a 4.6-fold higher risk for MACE. Conclusions: Genetic variants did not predict the risk of developing a MACE, neither in the pediatric nor in the adult cohort. Multivariate analysis emphasized reduced LV systolic function as the main independent factor that is elevating the risk for MACE. Genetic screening is useful for cascade screening to identify family members at risk for developing LVNC CMP.

Spontaneous Left Cardiac Isomerism in Chick Embryos: Case Report, Review of the Literature, and Possible Significance for the Understanding of Ventricular Non-Compaction Cardiomyopathy in the Setting of Human Heterotaxy Syndromes

The outer shape of most vertebrates is normally characterized by bilateral symmetry. The inner organs, on the other hand, are normally arranged in bilaterally asymmetric patterns. Congenital deviations from the normal organ asymmetry can occur in the form of mirror imagery of the normal arrangement (situs inversus), or in the form of arrangements that have the tendency for the development of bilateral symmetry, either in a pattern of bilateral left-sidedness (left isomerism) or bilateral right-sidedness (right isomerism). The latter two forms of visceral situs anomalies are called “heterotaxy syndromes”. During the past 30 years, remarkable progress has been made in uncovering the genetic etiology of heterotaxy syndromes. However, the pathogenetic mechanisms causing the spectrum of cardiovascular defects found in these syndromes remain poorly understood. In the present report, a spontaneous case of left cardiac isomerism found in an HH-stage 23 chick embryo is described. The observations made in this case confirmed the existence of molecular isomerism in the ventricular chambers previously noted in mouse models. They, furthermore, suggest that hearts with left cardiac isomerism may have the tendency for the development of non-compaction cardiomyopathy caused by defective development of the proepicardium.

Cardiomyopathy in Children: Classification and Diagnosis: A Scientific Statement From the American Heart Association

In this scientific statement from the American Heart Association, experts in the field of cardiomyopathy (heart muscle disease) in children address 2 issues: the most current understanding of the causes of cardiomyopathy in children and the optimal approaches to diagnosis cardiomyopathy in children. Cardiomyopathies result in some of the worst pediatric cardiology outcomes; nearly 40% of children who present with symptomatic cardiomyopathy undergo a heart transplantation or die within the first 2 years after diagnosis. The percentage of children with cardiomyopathy who underwent a heart transplantation has not declined over the past 10 years, and cardiomyopathy remains the leading cause of transplantation for children >1 year of age. Studies from the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry have shown that causes are established in very few children with cardiomyopathy, yet genetic causes are likely to be present in most. The incidence of pediatric cardiomyopathy is ≈1 per 100 000 children. This is comparable to the incidence of such childhood cancers as lymphoma, Wilms tumor, and neuroblastoma. However, the published research and scientific conferences focused on pediatric cardiomyopathy are sparcer than for those cancers. The aim of the statement is to focus on the diagnosis and classification of cardiomyopathy. We anticipate that this report will help shape the future research priorities in this set of diseases to achieve earlier diagnosis, improved clinical outcomes, and better quality of life for these children and their families.

Fetal left ventricular non-compaction cardiomyopathy with ascites: A case report

Here we report a case of fetal left ventricular non-compaction cardiomyopathy with ascites and cardiac dysfunction at a gestational age of 34⁺⁵  weeks. Laboratory tests did not reveal any sign of viral infection in utero. A female neonate weighing 2436 g was delivered by emergency cesarean section due to non-reassuring fetal status. Postnatal echocardiography confirmed left ventricular non-compaction cardiomyopathy with severe cardiac failure. Although she was treated effectively during the acute period by continuous flow peritoneal dialysis, surgical ligation of a patent ductus arteriosus, and inhaled nitric oxide, she died on day 41 of life. Symptoms of severe cardiac dysfunction appeared antenatally in this patient and the outcome was poor.

Assessment of Structural and Functional Abnormalities of the Myocardium and the Ascending Aorta in Fetus with Hypoplastic Left Heart Syndrome

Aims. To detect anatomical and intrinsic histopathological features of the ascending aorta and left ventricular (LV) myocardium and evaluate right ventricular (RV) function in fetuses with hypoplastic left heart syndrome (HLHS). Methods. Twenty-five fetuses diagnosed with HLHS were followed up in the antenatal and postpartum periods. 12 necropsy heart specimens were analyzed for morphological and histological changes. Results. Prenatal echocardiography and pathologic anatomy displayed the typical characteristics of HLHS as a severe underdevelopment of the LV in the form of mitral stenosis or atresia or as aortic atresia or stenosis, with a decreased ratio of aortic diameter to pulmonary artery diameter (median of 0.49 with a range of 0.24 to 0.69, p ≤ 0.001) and a higher ratio of RV diameter to LV diameter (median of 2.44 with a range of 1.33 to 6.25, p ≤ 0.001). The RV volume, stroke volume, and cardiac output in HLHS fetuses were increased compared with the gestational age-matched normal controls (p < 0.01). Histological changes in the 12 HLHS specimens included LV myocardial fibrosis, aortic elastic fragmentation, and fibrosis. Conclusions. In addition to severe anatomical deformity, distinct histological abnormalities in the LV myocardium and aortic wall were identified in the fetuses with HLHS. RV function damage may be potentially exists.

Fetal Ventricular Hypertrabeculation/Noncompaction: Clinical Presentation, Genetics, Associated Cardiac and Extracardiac Abnormalities and Outcome

Left ventricular hypertrabeculation/noncompaction (LVHT) is a cardiac abnormality of unknown etiology. Aim of the review was to summarize the current knowledge about fetal LVHT, including clinical presentation, associated cardiac and extracardiac abnormalities and outcome. In 88 cases, LVHT was diagnosed by fetal echocardiography. In 36 %, no additional cardiac abnormalities were reported; in the remaining 64 %, one or more cardiac abnormalities were reported. Eight cases died prenatally, 17 were electively terminated, and 24 patients died after birth. Six patients were lost to follow-up, and 33 patients are alive at a mean age of 26 months. Surviving cases presented less frequently with fetal hydrops (13 vs. 62 %, p = 0.0004), complete heart block (27 vs. 78 %, p = 0.0076), more than three associated cardiac abnormalities (9 vs. 47 %, p = 0.0008) and more frequently with isolated LVHT (52 vs. 19 %, p = 0.009) than cases who died. Of the surviving patients, 16 received pharmacotherapy, three received pacemakers, eight underwent surgical procedures and four underwent heart transplantation. Postnatal regression of left ventricular hypertrophy and development of LVHT was found in four cases, improvement in cardiac function in two, and regression of right VHT in two. At autopsy, endocardial fibrosis was the most frequent abnormality in 92 %. Thirty-eight percentage of cases with fetal LVHT survived. Fetal and postnatal echocardiographic findings challenge the "embryonic pathogenetic" hypothesis of LVHT. Furthermore, fetal pathoanatomic findings like endocardial fibrosis might play a role in clarifying the still unsolved pathogenesis of LVHT.