Arterial-Venous Balance in the Human Renal Vasculature: Renal-Aortic and Renal-Caval Ratios and Factors on Contrast-Enhanced Computed Tomography.

Background/

Objectives

A single absolute vessel diameter is hard to compare between individuals of differing body size. We defined two venous proportional parameters, the renal-caval ratio (R-IVCr) and factor (R-IVCf), as counterparts of the established renal-aortic ratio (R-Ar) and factor (R-Af), and asked whether the arterial and the venous bed respond to multiplicity of vessels in the same direction.

Methods

Biphasic contrast-enhanced computed tomography of the abdomen in 1196 patients (2392 kidneys) was analysed retrospectively. Ratios related the dominant vessel diameter to that of the parent trunk; factors related the summed cross-sectional area of a kidney's vessels to that of the corresponding trunk segment. Two angles, measured towards the left (α) and the right (β) from an anteroposterior reference axis, were recorded at both trunks.

Results

Mean R-Ar was 0.2381 (±0.0573) and mean R-IVCr was 0.4651 (±0.0943). Dominant-vessel ratios were lower in the multiple variant and area-summing factors were higher, in parallel on both sides (p < 0.001). All four were higher in men, with moderate effect sizes arterially and negligible ones venously. α and β inverted between the two trunks, which was the largest effect recorded, and multiple veins showed a 2.3-fold right-sided predominance.

Conclusions

The four parameters describe arterial inflow and venous outflow within a single proportional system in which both beds respond to multiplicity in parallel; their value in donor-kidney assessment and anastomosis planning awaits prospective validation.