Contribution to the study of the irrigation of the sinoatrial node in Landrace swines

Abstract

The irrigation of the sinoatrial node in Landrace swines was observed in 50 adults animals (25 males and 25 females), raised and slaughtered in the Centro Intraunidade de Zootecnia Industrias Pecuárias "Fernando Costa" (CIZIP) of the Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, Pirassununga, São Paulo. The results obtained allowed us to come to the following conclusions: 1) the portion occupied by the sinoatrial node is more commonly irrigated by collaterals of the ramus circunflexus of the arteria coronaria dextra (94.0% ± 2.8) or by the ones ramus circunflexus dexter (2.0% ± 2.0) , more precisely by the ramus proximalis atrii dextri. They were observed as a single vessel (88.0% ± 4.6) or a double one (8.0% ± 3.8), alone 10 times (20.0% ± 5.7) or associated* 25 times (50.0% ±7.1) with the ramus intermedius atrii dextri, also identified as a single vessel (26.0% ± 6.2) or a double one (24.0% ± 6.0) and, 13 times (26.0% ± 6.2) with the ramus distalis atrii dextri. 2) with less frequency, it is the ramus proximalis atrii sinistri that irrigates the portion occupied by the sinoatrial node, exclusively (2.0% ± 2.0) or associated with the ramus distalis atrii dextri, (2.0% ± 2.0). 3) arterial anastomoses, in which the vessels responsible for the arterial irrigation of the sinoatrial node take part in, were observed in 18 out of the 50 animals observed (36.0% ± 6.8). 4) Here was no statistically significant difference (at the level of 5.0%) for the several kinds of arterial irrigation of the sinoatrial node between males and females animals; however, differences were observed when different kinds of arterial vascularization, found in these animals and in the mongrel ones, were compared.