End-diastolic velocity mediates the relationship between renal resistive index and the risk of death.

OBJECTIVE: Renal resistive index predicts the risk of death in many populations but the mechanism linking renal resistive index and death remains elusive. Renal resistive index is derived from end-diastolic velocity (EDV) and peak systolic velocity (PSV). However, the predictive value of EDV or PSV considered alone is unknown. METHODS: We conducted a retrospective analysis of 2362 consecutive patients who received a kidney transplant from 1985 to 2017. EDV and PSV were measured at 3 months after transplantation, renal resistive index was calculated, and the risk of death was assessed [median follow-up: 6.25 years (0.25-29.15); total observation period: 13 201 patient-years]. RESULTS: Doppler indices were available in 1721 of 2362 (78.9%) patients (exclusions: 113 who died or returned to dialysis before, 427 with no Doppler studies, 27 with renal artery stenosis, 74 missing values). Among them, 279 (16.4%) had diabetes before transplantation. Mean age was 51.5 ±â€Š14.7, 1097 (63.7%) were male. During follow-up, 217 of 1721 (12.6%) patients died. Renal resistive index and EDV shared many determinants (notably systolic, diastolic and pulse pressure, recipient age and diabetes) unlike renal resistive index and PSV. EDV used as a binary [lowest tertile vs. higher values: (hazard ratio: 2.57 (1.96-3.36), P  < 0.001)] and as a continuous (the lower EDV, the greater the risk of death) variable was significantly associated with the risk of death. This finding was confirmed in multivariable analyses. Prediction of similar magnitude was found for renal resistive index. No association was found between PSV used as a binary or a continuous variable and the risk of death. CONCLUSION: Low EDV explains high renal resistive index, and the mechanism-linking renal resistive index to the risk of death is through low EDV.

Early changes in renal resistive index and mortality in diabetic and nondiabetic kidney transplant recipients: a cohort study.

BACKGROUND: Renal resistive index (RI) predicts mortality in renal transplant recipients (RTR). However, its predictive value may be different according to the time of measurement. We analysed RI changes between 1 month and 3 months after transplantation and its predictive value for death with a functioning graft (DWFG). METHODS: We conducted a retrospective study in 1685 RTR between 1985 and 2017. The long-term predictive value of changes in RI value from 1 month to 3 months was assessed in diabetic and non-diabetic RTR. RESULTS: Best survival was observed in RTR with RI < 0.70 both at 1 and 3 months, and the worst survival was found in RTR with RI ≥ 0.70 both at 1 and 3 months (HR = 3.77, [2.71-5.24], p < 0.001). The risk of DWFG was intermediate when RI was < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 2.15 [1.29-3.60], p = 0.003) and when RI was ≥0.70 at 1 month and < 0.70 at 3 months (HR = 1.90 [1.20-3.03], p = 0.006). In diabetic RTR, RI was significantly associated with an increased risk of death only in those with RI < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 4.69 [1.07-20.52], p = 0.040). RI considered as a continuous variable at 1 and 3 months was significantly associated with the risk of DWFG in nondiabetic but not in diabetic RTR. CONCLUSION: RI changes overtime and this impacts differently diabetic and nondiabetic RTR. RI short-term changes have a strong prognosis value and refines the risk of DWFG associated with RI.

The association between renal resistive index and premature mortality after kidney transplantation is modified by pre-transplant diabetes status: a cohort study.

BACKGROUND: Renal resistive index (RI) predicts mortality in renal transplant recipients, but we do not know whether this is true in diabetic patients. The objective of this study was to analyse the long-term predictive value of RI for death with a functioning graft (DWFG) in renal transplant recipients with or without pre-transplant diabetes. METHODS: We conducted a retrospective study in 1800 renal transplant recipients between 1985 and 2017 who were followed for up to 30 years (total observation period: 14 202 patient years). Donor and recipient characteristics at time of transplantation and at 3 months were reviewed. The long-term predictive value of RI for DWFG and the age-RI and arterial pressure-RI relationships were assessed. RESULTS: A total of 284/1800 (15.7%) patients had diabetes mellitus before transplantation. RI was <0.75 in 1327/1800 patients (73.7%). High RI was associated with a higher risk of DWFG in non-diabetic patients [hazard ratio (HR) = 3.39, 95% confidence interval 2.50-4.61; P < 0.001], but not in patients with pre-transplant diabetes (HR = 1.25, 0.70-2.19; P = 0.39), even after multiple adjustments. There was no interaction between diabetes and age. In contrast, there was an interaction between RI and pulse pressure. CONCLUSION: Our study indicates that RI is not a predictor of DWFG in diabetic renal transplant recipients, in contrast to non-diabetic recipients. These findings could be due to a different age-RI or pulse pressure-RI relationship.

Impact on renal resistive index of diabetes in renal transplant donors and recipients: A retrospective analysis of 1827 kidney transplant recipients.

High renal resistive index (RI) is observed in diabetes and is associated with poor patient survival, but whether it is primarily due to renal vascular resistance or systemic vascular alterations is unclear. The respective impact of kidney transplant from diabetic donors or to diabetic recipients on RI would shed some light on this issue. The objective of the study was to analyze the impact of donor and recipient diabetes on RI in order to understand the respective impact of the kidney and the vascular environment. The authors conducted a retrospective study in 1827 renal transplant recipients who received a kidney between 1985 and 2017, and had Doppler measurements at 3 months after transplant. Donor and recipient characteristics at the time of transplant and at 3 months were reviewed. Both donor diabetes and recipient diabetes were associated with RI in univariate analysis, but only recipient diabetes remained significantly associated in stepwise multivariate analyses (effect estimate on RI: +0.03 ± 0.005, P < 0.001). These findings were confirmed when RI was expressed as a binary variable using a cutoff of 0.75 (OR = 2.50 [1.77, 3.54], P < 0.001). Other determinants of RI were recipient characteristics (age, sex, systolic and diastolic blood pressure, and duration of dialysis). Donor characteristics were not associated with RI. Our results suggest that high RI observed in diabetic recipients shortly after transplant is primarily due to the new vascular environment, rather than to characteristics of the transplanted kidney. Therefore, RI reflects systemic rather than intra-renal changes.

Evaluation of Doppler-ultrasonography in the diagnosis of transjugular intrahepatic portosystemic shunt dysfunction: A prospective study.

AIM: To prospectively evaluate the performance of Doppler-ultrasonography (US) for the detection of transjugular intrahepatic portosystemic shunt (TIPS) dysfunction within a multicenter cohort of cirrhotic patients. METHODS: This study was conducted in 10 french teaching hospitals. After TIPS insertion, angiography and liver Doppler-US were carried out every six months to detect dysfunction (defined by a portosystemic gradient ≥ 12 mmHg and/or a stent stenosis ≥ 50%). The association between ultrasonographic signs and dysfunction was studied by logistic random-effects models, and the diagnostic performance of each Doppler criterion was estimated by the bootstrap method. This study was approved by the ethics committee of Tours. RESULTS: Two hundred and eighteen pairs of examinations performed on 87 cirrhotic patients were analyzed. Variables significantly associated with dysfunction were: The speed of flow in the portal vein (P = 0.008), the reversal of flow in the right (P = 0.038) and left (P = 0.049) portal branch, the loss of modulation of portal flow by the right atrium (P = 0.0005), ascites (P = 0.001) and the overall impression of the operator (P = 0.0001). The diagnostic performances of these variables were low; sensitivity was < 58% and negative predictive value was < 73%. Therefore, dysfunction cannot be ruled out from Doppler-US. CONCLUSION: The performance of Doppler-US for the detection of TIPS dysfunction is poor compared to angiography. New tools are needed to improve diagnosis of TIPS dysfunction.

Renal auto-transplantation promotes cortical microvascular network remodeling in a preclinical porcine model.

The vascular network is a major target of ischemia-reperfusion, but has been poorly investigated in renal transplantation. The aim of this study was to characterize the remodeling of the renal vascular network that follows ischemia-reperfusion along with the most highly affected cortex section in a preclinical renal transplantation model. There were two experimental groups. The first was a grafted kidney group consisting of large white pigs for which the left kidney was harvested, cold flushed, preserved for 24 h in the University of Wisconsin's preservation solution, and then auto-transplanted (n = 5); the right kidney was removed to mimic the situation of human kidney transplantation. The second group (uni-nephrectomized kidney group) consisted of animals that underwent only right nephrectomy, but not left renal transplantation (n = 5). Three months after autotransplantation, the kidneys were studied by X-ray microcomputed tomography. Vessel morphology and density and tortuosity of the network were analyzed using a 3D image analysis method. Cortical blood flow was determined by laser doppler analysis and renal function and tissue injury assessed by plasma creatinine levels and histological analysis. Renal ischemia-reperfusion led to decreased vascular segment volume associated with fewer vessels of less than 30 µm, particularly in the inner cortex:0.79 ± 0.54% in grafted kidneys vs. 7.06 ± 1.44% in uni-nephrectomized kidneys, p < 0.05. Vessels showed higher connectivity throughout the cortex (the arborescence factor of the whole cortex was less in grafted than uni-nephrectomized kidneys 0.90 ± 0.04 vs. 1.07 ± 0.05, p < 0.05, with an increase in the number of bifurcations). Furthermore, cortical blood flow decreased early in kidney grafts and remained low three months after auto-transplantation. The decrease in microvasculature correlated with a deterioration of renal function, proteinuria, and tubular dysfunction, and was associated with the development of fibrous tissue. This work provides new evidence concerning the impact of ischemia-reperfusion injuries on the spectrum of renal vascular diseases and could potentially guide future therapy to preserve microvessels in transplantation ischemia-reperfusion injury.

Trophic factor and FR167653 supplementation during cold storage rescue chronic renal injury.

PURPOSE: The use of organs from deceased after cardiac death and extended criteria donors grew in the last decade. These organs are more sensitive to ischemia-reperfusion injury during transplantation and current preservation protocols do not protect them adequately. MATERIALS AND METHODS: In an autotransplanted, deceased after cardiac death donor pig kidney model we evaluated the benefits of supplementation with University of Wisconsin solution trophic factors and FR167653, an inhibitor of p38 mitogen-activated protein kinase. RESULTS: Supplemented solution improved renal recovery and limited ischemia-reperfusion injury, particularly when agents were used in conjunction. Long-term benefits were highlighted by decreased renal fibrosis, as determined by Picrosirius staining, and inflammation, as evaluated by renal cell infiltration. Mechanistic evaluation showed decreased expression of epithelial-to-mesenchymal transition markers, a process involved in renal fibrosis development. Tumor necrosis factor-α was markedly decreased in the treated experimental group. Apoptosis was also decreased, accompanied by decreased p38 mitogen-activated protein kinase phosphorylation. CONCLUSIONS: Supplementing the current gold standard kidney preservation protocol with trophic factors and p38 mitogen-activated protein kinase inhibitors markedly increased the quality of grafts in our pig deceased after cardiac death donor model. Hence, this represents a strategy of interest to improve transplantation outcomes.

Normal ultrasound anatomy of the triangular fibrocartilage of the wrist: a study on cadavers and on healthy subjects.

PURPOSE: To report the normal sonographic anatomy of the triangular fibrocartilage (TFC) of the wrist in cadavers and volunteers. METHOD: Five hands from cadavers were examined sonographically before and after wrist dissection, during which the TFC was marked with surgical wires. Twenty volunteers without wrist limitation or pain, and without any history of wrist disease or inflammatory arthritis (mean age, 26 years (range,19-45 years) were also examined. RESULTS: Sonograms showed that the meniscus and the TFC were clearly separated. The meniscus appeared as a triangular structure that was homogeneous and slightly hyperechoic. Compared with the meniscus, the TFC appeared hypoechoic. The same patterns were observed for cadavers and volunteers. In 3 volunteers (15%), the TFC was not visualized. CONCLUSIONS: Using high-resolution ultrasound systems, the TFC can be separated from meniscus. However, visualization of the TFC remains limited due to its deep location and the presence of acoustic shadowing from bony structures.

Role of parametric imaging in contrast-enhanced sonography of hepatic focal nodular hyperplasia.

PURPOSE: To assess the value of parametric imaging during contrast-enhanced sonographic examination in the diagnosis of focal nodular hyperplasia (FNH) of the liver. MATERIALS AND METHODS: Thirty-one patients with solitary FNH underwent contrast-enhanced sonographic examination between January 2003 and June 2004 using SonoVue and a Sequoia scanner equipped with Cadence Contrast Pulse Sequencing software. Contrast enhancement from a time sequence of perfusion frames was estimated using QontraXt software, which provides quantification of perfusion parameters. From the time-intensity curves, we obtained the following parameters: peak enhancement value, Tr (time recovery corresponding to time needed to reach 63% of the peak value), beta parameter corresponding to the exponential factor, and slope corresponding to the slope of the tangent to the arterial phase of enhancement. RESULTS: Among the 4 parameters studied, the slope of the arterial phase of enhancement was the most sensitive to image the centrifugal arterial flow originating from the central portion of the lesion, whereas peak enhancement value and Tr were the most sensitive to image full enhancement of the lesion. A blinded review revealed equivalent sensitivity in the diagnosis of FNH between the interpretation of the original videoclips and that of the parametric images. CONCLUSIONS: The results of this study show that parametric imaging can be used in place of original videoclips for clinical reporting of FNH; furthermore, it could help less-experienced sonologists diagnose FNH.

Differential diagnosis of focal nodular hyperplasia with quantitative parametric analysis in contrast-enhanced sonography.

OBJECTIVES: We investigated the potential of quantitative parametric analysis in the differential diagnosis of focal nodular hyperplasia (FNH) from other hypervascularized liver focal lesions. MATERIALS AND METHODS: Eighty-five focal liver lesions (in 83 patients) were explored using contrast-enhanced ultrasound (SonoVue and Cadence Contrast Pulse Sequencing) consisting of typical FNH (n=52), hepatocellular carcinoma (n=11), hemangioma with high flow (n=8), hypervascular metastases (n=10), and hepatocellular adenoma (n=4). QontraXt software (AMID, Italy) was used here to estimate the following parameters: maximum peak value, Tr (time corresponding to time for obtaining 63% of the plateau), beta parameter corresponding to the exponential factor, and slope corresponding to the tangent value of the first phase of enhancement. These parameters were obtained from the time-intensity curves derived from the enhancement observed in 2 regions of interest corresponding, respectively, to the whole lesion and the central region only. RESULTS: A significant statistical difference (P<0.05) was found in the values of Tr, beta, and slope between FNH and other hypervascularized lesions on both the whole lesion and central region. Among these parameters, slope appeared as the most valuable whatever the region of interest, ie, central or whole lesion (P<0.01). Central region was more accurate in the differentiation of FNH and concordant with visual characterization. CONCLUSION: Quantitative parametric curve analysis of the different hypervascularized lesions confirms the depiction of the central artery in FNH and thus could help in differentiating this specific focal liver lesion from the others.

Modalities of surveillance after carotid endarterectomy: impact of surgical technique.

The purpose of this study was to assess the need for follow-up duplex scan (DS) 1 year after carotid endarterectomy (CE) performed with prosthetic patching and intraoperative completion arteriography. Between April 1994 and December 2000, a total of 605 CE procedures with prosthetic patch closure and intraoperative completion arteriography were performed in 540 patients. All patients underwent DS at 4 days and then yearly after the procedure. Five patients died during the early postoperative course and eight suffered a nonfatal stroke (combined neurological morbidity-mortality rate, 2.4%). Intraoperative completion arteriography showed abnormalities in 114 cases, including 17 involving the internal carotid artery (ICA) and 73 involving the external carotid artery (ECA). Successful revision was achieved in all cases and confirmed by repeat arteriography. Postoperative DS at 4 days detected three abnormalities involving the ICA (0.5%), including asymptomatic occlusion in one case and residual stenosis >50% in two cases. Ninety-eight percent of patients were stenosis-free at 1 year. Actuarial stroke-free survival was 98.3% at 3 years. Diameter reduction of the contralateral carotid artery progressed over 70% within 1 year after CE in 22.9% of patients with contralateral carotid stenosis over 50% at the time of the initial intervention. The findings of this study indicate that DS follow-up 1 year after CE with intraoperative completion arteriography is unnecessary unless postoperative DS demonstrates residual stenosis of the ICA. However, DS at 1 year is beneficial for patients presenting with contralateral carotid artery disease with diameter reduction >50% at the time of CE.

Carotid bypass with polytetrafluoroethylene grafts: a study of 110 consecutive patients.

BACKGROUND: Carotid endarterectomy (CEA) is the standard treatment for atherosclerotic lesions involving the carotid bifurcation. However, CEA can be challenging under some conditions. We describe the technique and outcome of prosthetic carotid bypass grafting (PCB) with polytetrafluoroethylene (PTFE) grafts as an elective alternative to CEA. PATIENTS AND METHODS: This retrospective analysis of prospectively collected data came from a series of 110 consecutive PCBs, that is, 9.6% of 1140 carotid revascularization procedures performed in our department between September 1986 and July 2002. Primary indications for PCB were extensive atherosclerotic lesions (n = 45, 40.9%), carotid stenosis associated with kinking (n = 29, 26.4%), recurrent stenosis (n = 18, 16.4%), and stenosis after radiation therapy (n = 7, 6.4%). RESULTS: The combined stroke and death rate at 30 days was 0.9%. Mean duration of follow-up was 647 +/- 71 days. Four carotid bypass grafts (3.6%) became occluded, and stenosis recurred in 1 (0.9%). At 3 years, overall actuarial survival was 81.4 +/- 11.5 and actuarial stroke-free rate was 97.7 +/- 2.3. There were no fatal strokes. CONCLUSION: PCB is a viable technique for treatment of extensive atherosclerotic carotid lesions, recurrent carotid stenosis, and carotid stenosis after radiation therapy. Postoperative stroke, occlusion, and recurrent stenosis rates are comparable to those associated with CEA performed under optimal conditions.