Arterial vascularization of the sinoatrial node in swine hearts: origin, distribution and quantification

The sinoatrial node, for being topographically installed as the initial component of the conduction system, is responsible for the production of the nervous impulses, which determines the cardiac contraction. There have been made studies related to the node's morphology in order to know the origin, distribution and quantification of the vases in this tissue, however, in spite of the results and quantitative data of the nodal irrigation - arterial vascular conduct and arterial vascular density, at the nodal level - the literature is scarce. With this objective 27 SRD swine hearts, injected with colored resin for macroscopic analysis of the origin and distribution of ANSA (sinoatrial node artery), 3 others injected with watery solution of colloidal coal (dyed nanquim) were used, to mark the route of the vases on the node level for stereological analysis. The atrial arteries originated as well from the right coronary artery as from the left one, with predominance of the first (66.66% and 33.33%, respectively). When originated from the right coronary artery, there existed the following branches: AADAM (right cranial medial atrial artery) in 14 cases, AADAI (right cranial intermedial atrial artery) in 2 cases, and AADAL (right cranial lateral atrial artery) in 2 cases. In 9 cases (33.33%) the following branches originated from the left coronary artery: 4 through branch AASPL (left caudal lateral atrial artery), 2 through branch AASAI (left cranial intermedial atrial artery) and 3 through branch AASAM (left cranial medial atrial artery). Interarterial anastomoses with vessels responsible for irrigation of the sinoatrial node area were observed in most of the cases (25 hearts). The Volume or Reference Volume (V(ref)) of the hearts were 35.32x10(4)µm³. For the stereological variables analyzed, the estimate density of the vessel length (Lv) was 766; the vessel length (L) - mm - was 27.06x10(5)µm; the area's surface density (Sv) was 182 and the area's surface (S) - mm² - was 64.3x10(6)µm². The estimate of the vascular numeric density (Nv(vasc)) - total of vessels per unit of volume (cm³) was 2.19 10-5, and the total number of vessels in the organ (N(vasc)), estimated by the physical dissector method in combination with the estimate of the number of Euler (Xv), was 773.6832 x10-2. The raised vascular density and total number of vases in the swine's sinoatrial node area suggests the existence of a vascular perinodal network complex and dense, ratifying the importance of this mark-pass for its blood supply.

Heart; vascularization; sinoatrial node; morphometry; swine