Do Mechanical Fluid Laws Dictate the Branching Pattern of the Renal Artery?

Introduction: Anatomy of the renal artery is an important issue in the renal transplantation era. Multi-detector computed tomography angiography (MDCTA) is an accurate modality for the preoperative assessment of live renal donors, and it provides excellent details of donor arterial anatomy. We studied the relationship between the angle of emergence of the renal artery from the aorta and its branching pattern. Methods: In this study, the MDCTA images obtained from the 138 kidneys of 77 potential renal transplant donors were studied. The courses of the right and left renal arteries from the aorta to the kidney hilus were delineated. The branching angle of the renal artery from the aorta (β, angle) and the length of the renal artery from the aorta until its first division were measured (Δ, distance). The renal artery deviation from the perpendicular plane of the aorta (D, factor of deviation) was calculated by the following formula: D = (1 - sin [β]). The cosine of this angle (cos [β]) was also calculated. Statistical analyses were performed with Pearson correlation tests. The P value was set at .05. Results: The mean age of patients was 28.7 +/- 4.3 with a male to female ratio of 63:14. The mean Δ distance and d{cyrillic} diameter were 34.37 +/- 10.68 mm (range, 10-58) and 6.13 +/- 1.37 mm (range, 2.8-9.9), respectively. The mean β angle, factor of deviation, and cos (β) were 62.19° +/- 16.44, 0.15 +/- 0.14, and 0.45 +/- 0.25, respectively. Significant negative correlations were found between the β angle, and Δ distance (r = -0.308; P < .001), and d{cyrillic} diameter (r = -0.303; P = .003). Factor of deviation and cos (β) were directly associated Δ distance and d{cyrillic} diameter. Conclusion: These findings indicated that with the main renal artery axis deviating from the perpendicular plane of the aorta or with a smaller branching angle, this artery had a greater diameter and underwent late branching. This study suggested that the renal artery diameter and branching pattern might be determined by the mechanical fluid laws.