Renal Artery Division Pattern of Black Africans about 50 Cases Treated by Injection-Corrosion Method

    

    

    Figure 3b:  Renal artery division pattern: rear view.
1: posterior artery
2: postero-superior segmental artery
3: superior postero-middle segmental artery
4: inferior postero-middle segmental artery
5: posterior branch of inferior segmental artery
    
    

• The retropyelic artery provided fewer segmental branches than the prepyelic artery. In 49 cases (98%), it was prolonged by a posterior segmental artery in the form of a concave arch inwardly pointing downwards and laterally (Figure 2b). From this arcade were born 4 to 5 branches destined mainly for mesorénal segment and superior pole. In one piece, the retropyelic artery gave 3 trunks superimposable to those of the anterior branch except for the inferior branch (Figure 3b).

• The superior polar artery, present in 3 cases (6%), vascularized the superior pole by its secondary branches. Its existence always coincided with the absence of the apical artery, branch of the prepyelic artery.

• The inferior polar artery, present in 4 cases (8%), vascularized the inferior pole by its secondary branches. Its existence always coincided with the absence of the inferior branch of the prepyelic artery.

Systematization

• Despite the differences in the arterial segmentation of each kidney, observations common to the kidneys were noted:

• The absence of anastomosis between the branches of the renal artery with a vascularization of the terminal type;

• The constant existence of the prepyelicanterior and retropyelicposterior arteries, branches of division of the renal artery;

• The existence of a convex avascular plane outside on the frontal plane; it is molded on the lateral edge of the mesorenal segment while being limited inside by the chalices;

• The existence of 2 anterior and posterior parenchymal territories which are separated by the chalices and the avascular plane.

The territorial arterial vascularization was thus:

The upper pole was entirely dependent on the apical artery in 36 cases (72%). If the apical artery did not exist, the superior pole completely depended either on the ramifications of the anterosuperior segmental artery in 7 cases (14%) or on the ramifications of the superior polar artery in 3 cases (6%). In 4 cases (8%), only the anterior valve of the superior pole depended on the antero-superior artery while the posterior valve depended on one of the branches of the retropyelic artery.

As for the mesorenal segment, the variations are less important. The anterior part of the mesorenal segment could be subdivided into 2 antero-superior and antero-inferior territories, each being dependent on the homologous segmental artery. In one case (2%), we had an antero-middle branch and therefore 3 territories in the anterior part of the mesorenal segment. The posterior territory of the mesorenal segment was dependent on a posterior segmental artery; in one case (2%), the retropyelic artery branched into 3 posterior segmental branches: postero-superior, postero-middle, and posteroinferior, dividing the posterior mesorenal segment into 3 territories (Figure 3b).

The lower pole was exclusively dependent on the inferior segmental artery, branch of the posterior artery in 46 cases (92%). This arterygived a branch for the anterior part of the inferior pole and another branch for the posterior part of the pole. The lower polar artery vascularized the entire lower pole in 4 cases (8%).

Discussion

Of all the arteries in the body, the renal arteries are among those with the greatest morphological variety. The purpose of this work is the systematization of arterial segmentation, we deliberately chose to inject and corrode only kidneys with a single renal artery so 80.5% of the pieces removed; kidneys with multiple renal arteries have undergone extensive dissection with skeletalization of the vessels, making difficult a injection-corrosion of quality.

The primary division branches of the renal artery

Although the bifurcation of the two-branched prepyelic and retropyelic renal artery is the divisional mode most commonly found by the majority of authors, we have also noted it in our series (80%), but this finding does not make unanimously. Some authors consider several other modes of division of the renal artery, the most common would be rather the trifurcation [1], this is the case of Ternon [2] and Kyle [3] which also does not find presegmental arteries in 49.3% of the 73 kidneys dissected during his study. In our series, the trifurcation of the renal artery in 3 presegmental branches was of the order of 20%.

• The polar presegmental branches:

They existed in 14% of cases. Several authors classify them in the polar arteries without distinction with the polar arteries arising from the aorta. Thus Sampaio [4] found 14% of polar arteries in his series, Satyapal [5] 10% and Edsman [6] 25% of polar arteries. This confusion could be avoided by clarifying the terminology, for example by retaining the term superior or inferior polar artery for a vessel that would arise from the aorta to penetrate directly to the upper or lower pole of the kidney, the term suprahilar artery or infrahilar for a vessel that would arise from the renal artery and would go directly to one of the kidney pole without passing through the hilum and renal artery any artery arising from the aorta and joining the hilum of the kidney.

The branches of secondary division of the renal artery

• Number of segmental arteries

Three to six segmental arteries are found per unit of kidney with a greater frequency of 5 segmental arteries (44%); exceptionally we found a kidney with 8 segmental arteries (Figures 3a and 3b). Thus, our results are similar to those of Sapte [7]. This author observes the existence of 3 to 6 segmental arteries with a preponderance of 5 segmental arteries per kidney in 42.78% of cases. Sampaio [8] found a number of segmental arteries varying between 4 and 5 with preponderance for 5 arteries found in 61.2% of cases.

• Distribution of segmental arteries

The apical segmental artery is the least common branch: 72% of the cases. The constant segmental branches are the anterosuperior segmental branch and the posterior segmental branch. Despite some disparities between our results and those reported in the literature, some commonalities are notable. Indeed, the majority of authors consider the posterior segmental artery to be a constant branch. Sampaio [8] during his work by the injection-corrosion method on 49 kidneys reports this constancy of the posterior segmental artery, Sapte [7] finds this same regularity on the 194 kidneys he studied with the same method than Sampaio, as well as Fine and Keen [9]. On the other hand, in his dissection work, Kyle [3] only found the posterior segmental branch in 75.3% of cases.

Systematization

The renal arterial ramifications noted that the segmentation of Graves [10] is still relevant. However, the apical segment did not always constitute a homogeneous vascular territory. Indeed in 8% of the cases of our series, it could be split into 2 parts anterior and posterior depending respectively on the prepyelic artery and the retropyelic artery. The avascular line of Hyrtl and Brodel is also a reality found on our molds and is therefore an incision area to be preferred.

Conclusion

The renal artery has many variations in its distribution. This study highlights the most common variations and is a database for conservative renal surgery but also the need to enrich the terminology of renal vessels.

References

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