Ultrasound Section, Policlinica Antônio Ribeiro Netto, Rio de Janeiro, Brazil.
Med Hypotheses. 2019 Mar;124:1-6. doi: 10.1016/j.mehy.2019.01.016. Epub 2019 Jan 24.
Doppler sonography is used as a routine test for detection of renal artery stenosis (RAS). Although increased peak systolic velocity at the site of the narrowing is a widely accepted method for assessing main renal artery stenosis, tardus parvus phenomenon detected on the downstream blood flow has been used as an alternative to direct insonation of the main artery. However, the uncertainty about the best Doppler parameter to be used for characterization of tardus parvus has yielded a variety of studies. Recently, the difference between the resistive index of the spleen and kidney (RISK) has been proposed as a potential marker of kidney damage and Doppler criterion for RAS in hypertensive patients without chronic kidney disease (CKD). The hypothesis of this study was to speculate further and propose the RISK as valuable new Doppler diagnostic criteria for the tardus parvus in CKD too. Data from 183 control patients and 135 chronic kidney disease patients (CKD) were included in the study to test the feasibility of the method and plausibility of the hypothesis. Criteria inclusion was a color Doppler ultrasound measurement of the renal (RRI) and spleen resistive index (SRI). Serum creatinine (0.83 ± 0.20 vs 3.27 ± 1.74), RRI (0.60 ± 0.06 vs 0.69 ± 0.09), SRI (0.55 ± 0.06 vs 0.58 ± 0.09), RISK (0.06 ± 0.04 vs 0.11 ± 0.08), and spleen size (94.1 ± 13.2 vs 100.8 ± 16.5) were higher in CKD patients (p < 0.05). RRI correlated with SRI in both groups; however, the coefficient of determination was different (Z = 2.29, p = 0.022). In the CKD group, RISK correlated inversely with age (r = -0.276; p = 0.001) and positively with creatinine (r = 0.509; p < 0.001). In the multivariate analysis, creatinine remained an independent predictor of the high RISK (Wald = 13.07; p < 0.001; odds ratio = 1.87; 95% confidence interval 1.33-2.62). Since extraneous factors similarly influence RRI and SRI, the SRI can be considered the correction factor that can estimate the cardiovascular burden on the RRI. Consequently, according to the suggested hypothesis, RISK helps to distinguish the tardus parvus related to RAS from tardus parvus related to systemic influences on Doppler morphology. The identification of the underlying mechanisms of tardus parvus, would help a more accurate characterization of the phenomenon and improve screening and diagnostic test for RAS in CKD patients.
多普勒超声检查已被用作检测肾动脉狭窄（RAS）的常规检查。尽管在狭窄部位检测到的收缩期峰值速度增加是评估主肾动脉狭窄的广泛接受的方法，但在下游血流中检测到的渐细渐弱现象已被用作主动脉直接照射的替代方法。然而，对于最佳多普勒参数用于描述渐细渐弱的不确定性，导致了各种研究。最近，脾肾阻力指数（RISK）的差异已被提出作为高血压患者无慢性肾脏病（CKD）的肾脏损伤和 RAS 的潜在标志物和多普勒标准。本研究的假设是进一步推测并提出 RISK 作为 CKD 中渐细渐弱的有价值的新多普勒诊断标准。该研究纳入了 183 名对照患者和 135 名慢性肾脏病患者（CKD）的数据，以测试该方法的可行性和假设的合理性。该标准包括彩色多普勒超声测量肾脏（RRI）和脾脏阻力指数（SRI）。血清肌酐（0.83±0.20 vs 3.27±1.74）、RRI（0.60±0.06 vs 0.69±0.09）、SRI（0.55±0.06 vs 0.58±0.09）、RISK（0.06±0.04 vs 0.11±0.08）和脾脏大小（94.1±13.2 vs 100.8±16.5）在 CKD 患者中更高（p<0.05）。RRI 在两组中均与 SRI 相关，但决定系数不同（Z=2.29，p=0.022）。在 CKD 组中，RISK 与年龄呈负相关（r=-0.276；p=0.001），与肌酐呈正相关（r=0.509；p<0.001）。在多变量分析中，肌酐仍然是高 RISK 的独立预测因子（Wald=13.07；p<0.001；优势比=1.87；95%置信区间 1.33-2.62）。由于外在因素同样影响 RRI 和 SRI，因此 SRI 可以被认为是估计 RRI 心血管负担的校正因子。因此，根据提出的假设，RISK 有助于区分与 RAS 相关的渐细渐弱与与多普勒形态的系统影响相关的渐细渐弱。渐细渐弱的潜在机制的识别将有助于更准确地描述该现象，并提高 CKD 患者的 RAS 筛查和诊断测试。
