1Department of Radiology Ogaki Municipal Hospital, 2Department of Cardiology Ogaki Municipal Hospital
Color Doppler, Renal interlobar artery, Essential hypertension
In this study, we used the color Doppler technique to measure renal blood flow velocity in 46 normal control patients (over 40 years old) and 70 patients with essential hypertension. For measurement, renal blood flow was assessed in the interlobular arteries along the right renal pyramid, which were identified under color Doppler guidance. Using the pulse Doppler system (SSD-3000; Aloka Co. Ltd.), we measured the maximum systolic blood flow velocity (Vmax), the minimum diastolic blood flow velocity (Vmin), and the time interval from Vmin to Vmax (Δt). We calculated the Vmax/Vmin ratio, the resistance index [RI= (Vmax-Vmin)/Vmax], and the acceleration index (AI=(Vmax-Vmin)/Δt). Comparisons were made between the normal control patients and the patients with hypertension. The Vmax/Vmin ratio and RI were significantly higher in the cases with hypertension than in the normal control patients, suggesting that intrarenal vascular resistance is elevated and renal blood flow is reduced. Although Δt was significantly prolonged and AI was significantly decreased, these changes were assumed to be secondary to the elevation of intrarenal vascular resistance. This method is non-invasive, features excellent reproducibility, and it would appear to be a useful diagnostic method for long-term observation of the clinical course of hypertension.