Objective: We recently demonstrated that the renal resistive index, measured after renal transplantation, reflects recipient characteristics, like recipient age and central hemodynamics, and not so much allograft function nor histology. In this study, we provide further evidence.

Methods: Aortic calcifications were measured by lateral lumbar X-ray in 262 recipients at the time of admission for renal transplantation. In a subgroup of patients, also pulse wave velocity (PWV) (n=119) and intima media thickness (IMT) (n=74) were measured. After transplantation, the renal resistive index, systolic (SBP) and diastolic blood pressure (DBP), pulse pressure, allograft function (eGFR), proteinuria, hematocrit and lipid blood tests were routinely measured at 3 months, 1 year and 2 years.

Results: There was a highly significant correlation between the severity of aortic calcifications of the recipient at transplantation and the resistive index measurements after transplantation (P<0.0001 at all time points). Also the IMT and PWV correlated with the resistive index (P<0.01 at all time points for all correlations). In the univariate repeated measurements model, recipients with higher resistive indices after transplantation were older, more likely diabetic and had higher body mass index. They had higher SBP, lower DBP, higher pulse pressures and lower hematocrit during follow-up and allograft function was also lower. When all significant variables were included in a multivariate mixed model, aortic calcifications, recipient age, diabetes, pulse pressure, DBP and hematocrit remained independently and significantly associated with the resistive index measurements after transplantation, whereas allograft function, donor age and recipient body mass index did not. In the subgroup of patients in whom also PWV and IMT was measured, PWV and IMT were not associated with the resistive index independently from the other covariates.

Conclusion: The renal resistive index measured regularly after renal transplantation depends on characteristics of the upstream vasculature of the recipient.

CITATION INFORMATION: Heylen L, Naesens M, Sprangers B, Heye S, Verhamme P, Jochmans I, Monbaliu D, Pirenne J, Kuypers D, Claes K. The Intrarenal Resistive Index Measured After Transplantation Is Determined by the Upstream Vascular System of the Recipient. Am J Transplant. 2016;16 (suppl 3).

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