To evaluate intrarenal arterial stiffness by Doppler ultrasound and examine the correlation between renal Doppler indices, glomerular filtration rate, and digital microvascular damage in systemic sclerosis patients.
Thirty systemic sclerosis patients and 30 healthy controls were enrolled in this study. Doppler indices of intrarenal arterial stiffness, peak systolic flow velocity, end diastolic flow velocity, resistive index, pulsative index, and systolic/diastolic (S/D) ratio were measured on the interlobar artery of both kidneys. Glomerular filtration rate was measured using Tc(99m) diethylenetriamine pentaacetic acid (DTPA). Equation 7 from the Modification of Diet in Renal Disease was used to estimate glomerular filtration rate. Nailfold videocapillaroscopy findings were classified as early, active, and late patterns.
The intrarenal arterial stiffness, evaluated by Doppler indices, was higher in systemic sclerosis patients than healthy controls. In systemic sclerosis patients pulsative index (r = -0.69), resistive index (r = -0.75), and S/D ratio (r = -0.74) showed a negative correlation with measured glomerular filtration rate (P < 0001). High correlation (P = 0008) was observed between measured and estimated glomerular filtration rate (r = 0.55). Pulsative index, resistive index, and S/D ratio significantly increased with progression of capillaroscopic damage. Conversely, measured glomerular filtration rate significantly decreased with capillaroscopic damage progression.
Doppler indices of intrarenal arterial stiffness are noninvasive diagnostic tests to evaluate renal damage in SSc patients. Intrarenal arterial stiffness and glomerular filtration rate correlate with capillaroscopic microvascular damage.