Key result
Fetal heart histology reveals highly variable intracardiac nerve density with deep nerves exposed during myocardial sculpturing.
Why the study?
Little information had been reported on deep intracardiac nerves in the myocardium of late human fetuses, including nerves at the atrial-pulmonary vein junction and in the atrial and ventricular septa.
Observational (n=12)
Detailed mapping of intracardiac nerves in late human fetuses reveals significant regional variations that may provide anatomical substrates for atrial fibrillation.
May support AF substrate hypotheses; leaves open persistence of fetal patterns into adulthood.
Few information had been reported on deep intracardiac nerves in the myocardium of late human fetuses such as nerves at the atrial-pulmonary vein junction and in the atrial and ventricular septa. We examined histological sections of the heart obtained from 12 human fetuses at 25-33 weeks. A high density of intracardiac nerves was evident around the mitral valve annulus in contrast to few nerves around the tricuspid annulus. To the crux at the atrioventricular sulcus, the degenerating left common cardinal vein brought abundant nerve bundles coming from cardiac nerves descending along the anterior aspect of the pulmonary trunk. Likewise, nerve bundles in the left atrial nerve fold came from cardiac nerves between the ascending aorta and pulmonary artery. Conversely, another nerves from the venous pole to the atrium seemed to be much limited in number. Moreover, the primary atrial septum contained much fewer nerves than the secondary septum. Therefore, nerve density in the atrial wall varied considerably between sites. As ventricular muscles were degenerated from the luminal side for sculpturing of papillary muscles and trabeculae, deep nerves became exposed to the ventricular endothelium. Likewise, as pectineal muscles were sculptured, nerves were exposed in the atrial endothelium. Consequently, a myocardial assembly or sculpture seemed to be associated with degeneration and reconstruction of early-developed nerves. A failure in reconstruction during further expansion of the left atrium might be connected with an individual variation in anatomical substrates of atrial fibrillation.
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Cho et al. (2019) reported an observational. Histological examination was evaluated on Nerve distribution in the myocardium. Histological examination of 12 human fetal hearts at 25-33 weeks demonstrated highly variable intracardiac nerve density, with deep nerves becoming exposed during myocardial sculpturing.
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