Objective: To determine the usefulness of intrarenal venous impedance index and pattern analysis of Doppler waveform in renal vein for evaluating functional status of kidney or cardiovascular system in normal population.
Materials and Methods: Between May 2007 and December 2008, Doppler sonography of both kidneys was performed in 98 volunteers who visited for health screening. Doppler waveform and impedance index of renal veins were obtained on the peripheral (interlobar) and central (segmental) renal veins. Doppler waveforms were divided into 3 class by shape (Type I: continuous with minimal fluctuation; Type II: monophasic: Type III: biphasic pattern). Waveforms and impedance indexes of patients were compared between right vs. left kidney and peripheral vs. central vein using the paired t test. Pattern analysis was performed between these variables.
Results: Mean venous impedance indexes of peripheral vein (0.36 ± 0.22) were significantly lower than central vein (0.47 ± 0.17) (p < 0.01). No significant difference was observed in mean venous impedance index between the right and left kidneys. Venous waveforms of kidneys showed 3 major pattern (type1 > type 3 > type 2, in freq.). No significant association was noted also in normal ranged blood pressure and renal function. However, the cases with hypertension or decreased renal function showed decreased phascity on Doppler wave form, resulting in decreased renal venous impedance.
Conclusion: Renal venous impedance indexes and pattern analysis may be helpful for detecting decreased renal function or hypertension. Our results could be reference value of normal venous impedance indexes