Epicardial neural plexus of the ovine heart

Abstract

Purpose: To determine the morphologic pattern of the epicardiac neural plexus (ENP) on total (non-sectioned) ovine hearts in order to assess its correspondence to the ENP in humans. Methods: Intrinsic cardiac neural plexus was revealed by a histochemical method for acetylcholinesterase on whole hearts of 4 sheep and 1 newborn lamb with their subsequent stereomicroscopic examination. Results: Mediastinal nerves accessing the ovine heart through venous part of the heart hilum proceeded separately into innervation regions by five epicardial ganglionated subplexuses, while nerves passing the arterial part of heart hilum formed two subplexuses, topography of which were corresponding to their topography in humans. The highest density of epicardiac ganglia was determined in the left dorsal and the dorsal right atrial subplexuses, which involved correspondingly 48 % and 23 % of the all ganglia counted within the ovine epicardium. The largest in cumulative area ganglia were concentrated near sinoatrial node on the root of the right cranial vein (RRCV) and in the ventral superior right atrial region. The mean cumulative area of epicardiac ganglia distributed on the RRCV was 2,25 mm 2 in a lamb and 6,24 mm 2 in adult sheep. The mean cumulative area of epicardiac ganglia on the ventral superior right atrial region was 1,38 mm 2 in a lamb and 3,23 mm 2 – in adult sheep hearts. Conclusion: The richest in ganglia sites on the ovine epicardium are concentrated at the RRCV and this is in sharp contrast to the human ENP, in which the majority of ganglia are located on the dorsal surface of the left atrium.