Associations of Renal Augmented Velocity Index with Arterial Stiffness, Carotid Intima-Media Thickness and Blood Pressure, in Comparison with Renal Resistive Index

The Relationship of Renal Augmented Velocity Index With Ventricular-Arterial Coupling in Comparison to Renal Resistive Index: Analysis by Means of Arterial and Ventricular Elastances in Hypertensive Patients

OBJECTIVE

It's a well-known scientific statement that the heart and kidney functions are frequently tied together and the impairment of one directly alters the other. However, there exist knowledge gaps about this intricate pathophysiologic link and the exact unifying mechanism is not established. Herein, we aimed to investigate the presence of cardiorenal interaction at subclinical level while the conventional cardiac and renal clinical parameters are not disrupted yet in patients with hypertension.

METHODS

We chose a novel renal Doppler ultrasonographic parameter-augmented velocity index (Avi)-and an echocardiographic measure-ventriculoarterial coupling-which is complex to analyze but increasingly used after its acceptance about being a key determinant of cardiovascular efficiency. We recruited 137 patients without a previous history of antihypertensive medication use (47.4% women; median age, 49 years). Renal Avi, renal resistive index (RI), arterial elastance (Ea ), ventricular elastance (Ees ) and Ea /Ees (ventriculoarterial coupling) parameters were all examined.

RESULTS

Renal Avi, Ea , and Ea /Ees values were higher in females. Correlation analysis revealed that renal Avi was correlated with many hemodynamic variables including Ea and Ea /Ees . On multiple linear regression analysis, Ea and Ea /Ees remained as significant independent predictors of renal Avi but not of renal RI after adjustments for co-variables (β = 0.488, P < .001 for Ea ; β = 0.380, P < .001 for Ea /Ees ).

CONCLUSIONS

In comparison to renal RI, we suggest that renal Avi is a more reliable and promising index that can even measure subclinical changes in the cardiorenal circulation which needs to be elucidated.

Current Insights into the Significance of the Renal Resistive Index in Kidney and Cardiovascular Disease

Initially, the renal resistive index (RRI) was investigated with the aim of improving diagnosis in kidney diseases, but this goal was not met. Recently, many papers have highlighted the prognostic significance of the RRI in chronic kidney disease: specifically, in estimating the revascularization success of renal artery stenoses or the evolution of the graft and the recipients in renal transplantation. Moreover, the RRI has become significant in the prediction of acute kidney injury in critically ill patients. Studies in renal pathology have revealed correlations of this index with parameters of systemic circulation. The theoretical and experimental premises of this connection were then reconsidered, and studies analyzing the link between RRI and arterial stiffness, central and peripheral pressure, and left ventricular flow were conducted with this purpose. Many data currently indicate that RRI is influenced more by pulse pressure and vascular compliance than by renal vascular resistance-assuming that RRI reflects the complex interplay between systemic circulation and renal microcirculation and should be considered a marker of systemic cardiovascular risk beyond its prognostic relevance for kidney disease. In this review, we overview the clinical research that reveals the implications of RRI in renal and cardiovascular disease.

Sonographic Measurement of Mesenteric Fat Thickness Is a Better Predictor of Aortic Stiffness Compared With Conventional Obesity Indexes

Increased aortic stiffness is closely associated with central obesity whereas mesenteric fat is the key adipose tissue in central obesity. We investigated the associations of mesenteric fat thickness with aortic stiffness, with comparison to conventional obesity measures. We used ultrasound to measure mesenteric, pre-peritoneal and subcutaneous fat thickness, carotid intima-media thickness (CIMT) and carotid-femoral pulse wave velocity (c-f PWV), an index of central aortic stiffness. Anthropometric indexes, blood pressure, fasting plasma glucose and lipid profile were measured. One hundred forty-seven healthy volunteers (age [mean ± standard deviation]: 43.2 ± 13.3 y; 41.5% men) were assessed. On univariate analysis, mesenteric, preperitoneal and subcutaneous fat thickness, body mass index (BMI), waist circumference (WC), waist/hip ratio (WHR) and waist/height ratio (WHtR) were associated with c-f PWV with or without adjustment for age. The mesenteric fat thickness had the highest correlation coefficient (r = 0.48, p < 0.001) with c-f PWV among all the investigated obesity indexes. Using multiple linear regression analysis, only mesenteric fat thickness remained to be an independent determinant of c-f PWV after adjustments for other abdominal fat thickness, anthropometric and metabolic indexes and CIMT. In conclusion, mesenteric fat thickness is an independent risk factor for aortic stiffness and has a stronger association with aortic stiffness compared with conventional obesity indexes.