Anatomical study of the neural ganglionated plexus in the canine right atrium: Implications for selective denervation and electrophysiology of the sinoatrial node in dog

Abstract

The aim of the present study was to elucidate the topography and architecture of the intrinsic neural plexus (INP) in the canine right atrium because of its importance for selective denervation of the sinoatrial node (SAN). The morphology of the intrinsic INP was revealed by a histochemical method for acetylcholinesterase in whole hearts of 36 mongrel dogs and examined by stereoscopic, contact, and electron microscopes. At the hilum of the heart, nerves forming a right atrial INP were detected in five sites adjacent to the right superior pulmonary veins and superior vena cava (SVC). Nerves entered the epicardium and formed a INP, the ganglia of which, as a wide ganglionated field, were continuously distributed on the sides of the root of the SVC (RSVC). The epicardiac ganglia located on the RSVC were differentially involved in the innervation of the sinoatrial node, as revealed by epicardiac nerves emanating from its lower ganglia that proceed also into the atrial walls and right auricle. The INP on the RSVC (INP-RSVC) varied from animal to animal and in relation to the age of the animal. The INP-RSVC of juvenile dogs contained more small ganglia than that of adult animals. Generally, the canine INP-RSVC included 434+/-29 small, 17+/-4 medium-sized, and 3+/-1 large epicardiac ganglia that contained an estimated 44,700, 6,400, and 2,800 neurons, respectively. Therefore, the canine right atrium, including the SAN, may be innervated by more than 54,000 intracardiac neurons residing mostly in the INP-RSVC. In conclusion, the present study indicates that epicardiac ganglia that project to the SA-node are distributed more widely and are more abundant than was previously thought. Therefore, both selective and total denervation of the canine SAN should involve the whole region of the RSVC containing the INP-RSVC.

Autonomic cardiac nerves: literature review

“…Usually, they form several nerve clusters located in the epicardium, in several regions of the heart: the base of the heart as well as in the region of the interatrial, coronary, and interventricular grooves. Studies have shown that the human heart contains an average of 836 ganglia [49]; this translates into about 14,000 neurons [5], The heart of a pig has 82 ganglia formed by over 1,600 neurons [6], while the heart of a dog has about 440 small ganglia containing an average of 2,800 neurons, about 20 medium-sized ganglia containing an average of 6,400 cells, and 1-3 large ganglia containing over 44,000 neurons [50]. On the other hand, Yuan et al [68] showed the presence of only about 260 cardiac ganglia in dogs.…”

Características estruturais e estereológicas do plexo cardíaco de camundongos expostos à poluição ambiental

“…Em relação à arquitetura geral do plexo cardíaco, a coloração de acetilcolinesterase (AChE) demonstrou ser um método eficiente para o seu mapeamento, como já descrito em diferentes mamíferos como o cão (Pauza et al, 1999;2000); o homem (Hopikins, 2000) e o rato (Batulevicius, 2003;Arora et al, 2003;Rysevaite et al, 2011). Quando se compara as observações da inervação do coração de camundongo com os trabalhos realizados com corações de ratos (Batulevicius, 2003;Rysevaite et al, 2011), evidencia-se uma semelhança da anatomia dos componentes do plexo cardíaco.…”