Anatomic study of normal hepatic vein outflow tract and its adjacent structure in Chinese

Abstract

Objective To provide anatomic basis for the clinical application, the data were obtained by utilizing anatomic study of normal hepatic venous (HV) outflow tract and its adjacent structure in Chinese. Methods The data were observed and measured in 57 normal adult cadaver from March 2014 to March 2015. The following parameters were obtained: the opening form of left hepatic vein (LHV), middle hepatic vein (MHV) and right hepatic vein (RHV) drained into the inferior vena cava (IVC). The relationship of horizontal position among the openings of LHV, MHV and RHV. The position relations between openings of HV and diaphragm hiatus. The opening diameters of LHV, MHV and RHV, and the distances from the upper margin of HV to diaphragm hiatus were compared. The morphology of the diaphragm hiatus and the structure in the space between IVC and the wall of the hiatus were observed. The long diameter and short diameter of the diaphragm hiatus were compared. Quantitative data difference between two samples was analyzed by independent-sample t test, and the difference among more samples was analyzed by one-way ANOVA. LSD-t test was used in the comparison between any two means. Results There were four opening forms of HV in 57 cases. The probability of HV with two openings(LHV+ MHV, RHV) joining into IVC was 73.68%(42/57), with three openings (LHV, MHV, RHV) joining into IVC was 17.54%(10/57), with the right superior vein which joins into IVC directly at the side of the RHV was 5.26%(3/57), with cable structure in the opening of RHV was 3.51% (2/57). The opening diameters of LHV, MHV and RHV were (9.25±1.84)mm, (8.94±1.52)mm, and (14.29±2.84)mm, respectively. The diameter of RHV was larger than that in LHV and MHV(all P values<0.01). The probability of the upper margin of LHV or main trunk (LHV+ MHV) which was higher than the upper margin of RHV was 85.96% (49/57). The probability of the openings of them in the same horizontal plane was 14.04% (8/57). Openings of RHV in 39 cases and openings (LHV+ MHV) in 37 cases were below the diaphragm hiatus. Besides, the upper margin of common opening (LHV+ MHV) was located above the diaphragm hiatus in 2 cases. The distances between the upper margin of LHV and diaphragm hiatus, the upper margin of MHV and diaphragm hiatus, the upper margin of RHV and diaphragm hiatus were (3.19±0.74) mm, (3.62±0.81) mm, and (9.03±3.02) mm, respectively. The distance between the upper margin of RHV and diaphragm hiatus was larger than that in LHV and MHV(P<0.01). The long diameter of diaphragm hiatus was (26.94±3.47) mm and the short diameter was (19.62±2.80) mm. The difference between them was considered as statistically significant (t=10.242, P<0.01). Hematoxylin-eosin staining showed that large amount of fibrous connective tissues were distributed in the space between IVC and the wall of the tissue. Conclusions In normal adults, main trunk (LHV+ MHV) is the most frequent in the opening form of HV drained into the IVC. Mostly, the upper margin of main trunk (LHV+ MHV) is higher than the upper margin of RHV. A small number of openings of RHV have the cable structure. Compared to RHV, the openings of LHV and MHV are much closer to the diaphragm hiatus. The upper margin of LHV or common opening (LHV+ MHV) is located above the diaphragm hiatus in a small number of cases. Large amount of fibrous connective tissues distribute in the gap between IVC and the wall of diaphragm hiatus. The central key from diaphragm is not attached directly to IVC at diaphragm hiatus. This information is very important for the clinical research and the choice of the treatment of disease which is related to HV outflow tract. Key words: Hepatic veins; Outflow tract; Vena cava, inferior; Diaphragm; Anatomy