Early and long-term results after reconstructive surgery in 42 children and two young adults with renovascular hypertension due to fibromuscular dysplasia and middle aortic syndrome.

OBJECTIVES: This retrospective study presents the early and late results of pediatric patients who underwent reconstructive surgery for renovascular hypertension (RVH) between 1979 and 2009. METHODS: From 1979 to 2009 44 patients (male 22; mean age 13±5.2 years, range 1-19 years; early childhood 7 [1-6 years], middle childhood 5 [7-10 years]; adolescents 32 [11-19 years]) with renovascular hypertension underwent surgery for abdominal aortic stenoses (n=6), renal artery stenosis (RAS) (n=25) or for combined lesions (n=13). Nineteen aortic stenoses (bypass/interposition 10/5, patch dilatation/thromboendarterectomy 2/2), 51 renal arteries (interposition 36, resection+reimplantation 13, patch dilatation/aneurysmorraphy 1 each), and 10 visceral arteries (resection+reimplantation 6, interposition 3, patch dilatation 1) were reconstructed. Each patient underwent duplex studies and if required intra-arterial digital subtraction angiography. Reoperations within 30 postoperative days were required in four (9%) of the patients for occlusion of four arteries (6%), achieving a combined technical success rate of 94%. RESULTS: After 114±81 months 36 patients were re-examined by duplex and magnetic resonance angiography (2 not surgery-related deaths 7/12 years postoperatively, 8 patients lived abroad). Twelve patients had required a second and three a third procedure. Hypertension was cured early/late postoperatively in 27%/56%, improved in 41%/44%, and remained unchanged in 32%/0%. Best late results were obtained in patients with isolated aortic disease and at the age of middle childhood. CONCLUSIONS: Reconstructive surgery for pediatric RVH yields good results at every age and every type of lesion. However, these children should be followed up closely and to avoid early cardiovascular disease and death in later life, surgery should not be delayed.

Fibromuscular dysplasia in living renal donors: still a challenge to computed tomographic angiography.

BACKGROUND: Computed tomographic angiography has become the standard evaluating method of potential living renal donors in most centers. Although incidence of fibromuscular dysplasia is low (3.5-6%), this pathology may be relevant for success of renal transplantation. The incidence of FMD in our population of LRD and reliability of CTA for detecting vascular pathology were the aims of this study. MATERIALS AND METHODS: 101 living renal donors, examined between 7/2004 and 9/2008 by CTA, were included in a retrospective evaluation. The examinations were carried out using a 64 Multi-detector CT (Siemens Medical Solutions, Erlangen). The presence or absence of the characteristic signs of fibromuscular dysplasia, as "string-of-beads" appearance, focal stenosis or aneurysms, were assessed and graded from mild (=1) to severe (=3). Furthermore, vascular anatomy and arterial stenosis were investigated in this study. Retrospective analysis of CTA and ultrasound were compared with operative and histological reports. RESULTS: Four cases of fibromuscular dysplasia (incidence 3.9%) in 101 renal donors were diagnosed by transplanting surgeons and histopathology, respectively. Three cases could be detected by CTA. In one donor even retrospective analysis of CTA was negative. Ten accessory arteries, 14 venous anomalies and 12 renal arteries stenosis due to atherosclerosis were diagnosed by CTA and could be confirmed by the operative report. CONCLUSION: CTA is sufficient for detection of hemodynamic relevant stenosis and vascular anatomy. Only one patient with a mild form of FMD was under estimated. Therefore, if the CTA shows slightest irregularities which are not typical for atherosclerotic lesions, further diagnostic work up by DSA might still be necessary.

Renal cysts in living donor kidney transplantation: long-term follow-up in 25 patients.

INTRODUCTION: The acceptance of a living donor kidney bearing cysts might implicate complications after the transplantation due to the natural history of renal cysts. We have presented our experience with transplantation of living donor kidneys containing cysts but not polycystic disease. PATIENTS AND METHODS: We retrospectively reviewed donor and recipient records of all living kidney transplants performed between January 1997 and April 2008. We analyzed serum creatinine and urea levels, as well as ultrasound scans concerning cyst size and morphology at hospital discharge as well as at 12 and 24 months after transplantation. RESULTS: Among 268 living kidney transplantations, we noted 25 donors with renal cysts. In the computed tomography scan reports, 19 kidneys were described to show a single and six, multiple cysts. The size of 10 single cysts was <5 mm; the other nine were a mean of 17.33 mm. Two of the multiple cyst kidneys had lesions <5 mm; in four kidneys, the mean cyst size was 27.25 mm. The renal function of the recipients was normal or almost normal at discharge with a tendency to lower levels at 12 and 24 months after transplantation. Ultrasound revealed changes in cyst diameter among 6/23 kidneys; the mean diameter increased after 12 months, namely, 8.25 mm to 11.5 mm after 24 months. The subgroup of patients with enlarged cysts showed creatinine and urea levels slightly higher than in the entire group. No aspects of malignancy were found, according to the Bosniak and Israel classification system. One suspicious cyst was tomographically confirmed to be hemorrhagic without any need for treatment. None of the living donors had any problems related to the donor nephrectomy or a need for dialysis due to renal insufficiency in the long term. In addition, the living donors who had even beforehand cystic lesions in their contralateral nonremoved kidney at the time of transplantation did not show complications upon follow-up. CONCLUSIONS: In our study, 25 living donor kidneys carried cysts. Neither cyst-related complications nor dysfunction of the transplanted organs occurred. An unroofing or excision of the cyst was generally not necessary. Regular ultrasound scans and optional computed tomography scans are recommended for follow-up. Based on this experience, we concluded that kidneys presenting cystic diseases should be considered to be suitable for transplantation without a hazard to the recipients, thus extending the pool of organs.

[Functional MRI of transplanted kidneys using diffusion-weighted imaging]. / Funktionelle MRT der Transplantatnieren: klinische Wertigkeit der Diffusionsbildgebung.

PURPOSE: Contrast-enhanced MRI is considered problematic in renal allograft recipients due to the association of gadolinium administration and the development of NSF. Therefore, we assessed the clinical value of mono- and biexponential analysis of diffusion-weighted imaging (DWI). MATERIALS AND METHODS: A total of 32 patients were divided into four groups: (a) patients with stable function of renal allograft for at least 6 months, (b) patients with acute deterioration of allograft function, patients who recently underwent transplantation (< 14 days) with good (c) or decreased (d) renal function. T 2w ax. and T 1w cor. and a diffusion-weighted sequence with 16 b-values (b = 0 - 750 s/mm (2)) were performed on a 1.5 T scanner (Magnetom Avanto, Siemens Medical Solutions). ROI-based analysis of the renal cortex was analyzed using the software "Table Curve 2D". RESULTS: Monoexponential analysis showed an ADC (mono) of 1961 +/- 104 1801 +/- 150, 2053 +/- 169 and 1720 +/- 191 10 (-6)mm (2) /sec for patient group a, b, c and d respectively. The difference in ADC (mono) between group (a) and (b) (p < 0.006) and between group (c) and (d) (p < 0.04) was statistically significant. Biexponential analysis revealed a mean perfusion fraction of 0.21, 0.23, 0.32 and 0.24 for group (a), (b), (c) and (d), respectively. Biexponential ADC showed a higher numerical accuracy. There were no statistically significant inter-group differences in diffusion (ADC (D)) and perfusion (ADC (P)). CONCLUSION: Unenhanced evaluation of renal allografts with DWI is feasible. ADC (mono) of renal cortex correlates with renal function. The significance of the higher numerical accuracy of biexponential analysis in clinical settings requires further evaluation in larger-scale studies.

[Hypertension in patients with renal artery stenosis]. / Hypertonie bei Patienten mit Nierenarterienstenosen.

Renal artery stenosis (RAS) is often present in patients with severe hypertension and atherosclerotic vascular disease. In this setting it is important to screen patients for renovascular disease, e.g. with Duplex-ultrasound, CT- or MR-angiography. The challenge of treating these patients is to find the evidence proving that the RAS is responsible for hypertension and/or renal dysfunction. Measurement of the intra-arterial pressure gradient is necessary in order to determine hemodynamic relevance. On the other side, in these patients hypertension is often of primary and/or renoparenchymatous origin and is aggravated by a renovascular disease. This explains why hypertension cannot be cured even if a high grade stenosis has been removed. In addition, thromb- and cholesterol-embolic material is often mobilized during an invasive procedure and leads to renaparenchymatous ischemia which sustains hypertension after intervention. An individual evaluation of profit versus risk is important for the decision for or against an invasive procedure, especially since there is no sufficient evidence for a decrease of mortality after interventions of RAS. The optimal conservative treatment, including the treatment of atherosclerotic risk factors is recommended.

Prospective age-matching in elderly kidney transplant recipients--a 5-year analysis of the Eurotransplant Senior Program.

Renal transplantation faces challenges: the organ shortage resulting in extended waiting times and an aging population resulting in death with a functioning graft. The Eurotransplant Senior Program (ESP) allocates kidneys within a narrow geographic area from donors aged >/=65 years to recipients >/=65 years regardless of HLA. This analysis investigates the impact of the ESP on waiting time, graft and patient survival. The ESP group (n = 1406, old to old) was compared to two groups allocated via the Eurotransplant Kidney Allocation System (ETKAS) with either similar donor age (old to any [O/A], donor age >/=65, n = 446) or recipient age (any to old, [A/O], recipient age 60-64, n = 1687). All patients were transplanted between 1999 and 2004. Since initiation of the ESP (1999), availability of elderly donors doubled and waiting time for ESP patients decreased. Local allocation led to shorter cold ischemia time (11.9 vs. >17.0 h, p < 0.001) and less delayed graft function (DGF, ESP 29.7% vs. O/A 36.2%, p = 0.047) but 5-10% higher rejection rates. Graft and patient survival were not negatively affected by the ESP allocation when compared to the standard allocation. The ESP age matching of elderly donors and recipients is an effective allocation system for organs from elderly donors.

Intravenous iloprost: a new therapeutic option for patients with post-transplant distal limb syndrome (PTDLS).

The purpose of this study was to investigate the application of intravenous iloprost as a novel therapy for the treatment of post-transplant distal limb syndrome (PTDLS). PTDLS is a benign but disabling complication in the first year after renal transplantation. It is characterized by bilateral, often incapacitating pain in the feet and or knees on motion and a significant rise in alkaline phosphatase levels on laboratory evaluation. On MRI, bone marrow edema of the affected bone regions can be demonstrated. PTDLS differs from steroid induced osteonecrosis of the hip in terms of localization, an average cumulative steroid dosage within expected limits, and a benign outcome, as PTDLS does not progress to overt cell necrosis. From August 2003 to April 2005 we treated 10 patients with MRI-proven diagnosis of PTDLS following a standardized regimen of intravenous iloprost over 5 days. Iloprost led to prompt pain relief measured on a visual analogous scale (VAS) ranging from 1 to 10 (5.6 +/- 1.5 before vs. 2.1 +/- 1.3 after treatment, p = 0.0004). PTDLS represents a benign but disabling complication following renal transplantation. Intravenous iloprost might be a promising therapeutic concept leading to a quick relief of symptoms without relevant side effects.

Renovascular disease: a review of diagnostic and therapeutic procedures.

The clinical importance of renovascular disease, atherosclerotic or of other origin, arises from the fact, that renal artery stenosis (RAS), if hemodynamically significant (> 70% diameter reduction), induces arterial hypertension, renal insufficiency or both. The prevalence of RAS rises with increasing age and with the presence of atherosclerosis of the aorta, carotid, coronary and peripheral arteries. Typical clinical symptoms, as uncontrolled hypertension or renal dysfunction in the absence of pathological urinary findings, are helpful to select patients for further screening methods: We see a prominent role of color duplex sonography as a screening procedure. Intra-arterial angiography remains gold standard for the diagnosis of RAS. The major problem in daily clinical practice is the differentiation between patients in which hypertension and kidney function can be improved or normalized by removal of RAS and those with ''fixed'' hypertension and irreversible kidney dysfunction and therefore to decide if it is worth while to perform invasive treatment as angioplasty or surgery. In this setting, the proof of hemodynamic significance is essential and is indicated especially when the stenosis has a diameter reduction of < 50-70% only. Methods proving a critical stenosis are intra-arterial measurement of the pressure gradient, measurement of differential renal vein renin and duplex sonography. In addition, predictors of treatment outcome should be considered. Studies analyzing if patients improve with blood pressure and kidney function after removal of RAS have shown that high grade stenosis and/or very high blood pressure indicate a good outcome. Further prognostic factors are the absence of parenchymal disease and/or positive functional test. In the presence of a critical stenosis in a patient with a clear clinical problem with hypertension and/or renal dysfunction a positive effect of invasive treatment seems warranted despite the risks that must be considered as well in angioplasty as in surgery. The selection for the type of invasive treatment requires a clarification of the treatment goals in the individual patient, the evaluation of the morphology and localization of the stenosis as the presence of other vascular disease (aortic aneurysm, peripheral artery disease etc.) and the assessment of the risk according to the type of intervention.

Successful treatment of renovascular hypertension has no effect on insulin sensitivity.

BACKGROUND: The association of insulin resistance (IR) and essential hypertension is well known, but a causal relationship has not been proven. Patients with secondary hypertension as a result of renal artery stenosis (RAS) usually do not reveal IR, but no study has addressed the effect of blood pressure reduction after successful treatment of RAS on insulin sensitivity and glucose effectiveness. PATIENTS AND METHODS: The insulin sensitivity index (SI) and glucose effectiveness (SG) were measured before and after successful intervention of an angiographically proven significant RAS in 18 out of 23 patients (eight males/10 females; mean age 51.5 +/- 13.1 years) in which improvement/cure of arterial hypertension was achieved. After a mean of 10.7 months, patients were reevaluated for 24-h blood-pressure measurement, kidney function, adrenaline, noradrenaline, plasma-renin-activity (PRA), aldosterone, atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP), and glucose metabolism parameters such as basal insulin, glucose disappearance constant (K-value), SI and SG. For calculation of SI and SG, insulin and glucose data from the modified frequent sampling intravenous glucose tolerance test (FSIGT) were submitted to the MINMOD program. RESULTS: After intervention, systolic 24-h blood pressure had decreased from 156.1 +/- 16.4 mmHg to 139.9 +/- 15.1 mmHg, and diastolic 24-h blood pressure from 97.1 +/- 14.7 mmHg to 87.3 +/- 13.4 mmHg. No significant change in SI (before 4.3 +/- 2.0, after 4.8 +/- 2.0 min(-1) per microU mL(-1)) or SG (before 1.55 +/- 0.42x10(-2) min(-1), after 1.8 +/- 0.48x10(-2) min(-1)) was observed. Aldosterone decreased from 246.7 +/- 180.7 to 115 +/- 61.4 (P=0.009) as PRA decreased from 12.4 +/- 11.4 to 4.2 +/- 7.6 ng mL h(-1) (P=0.01). Creatinine clearance, and adrenaline and noradrenaline levels as well as ANP and cGMP did not change after treatment for RAS. Subsequent to the definition of IR (SI < or =3.2x10(-4) min(-1) per microU mL(-1)) some differences among these two subgroups (SI < or =3.2, or SI>3.2) could be found. Patients with IR (n=8) were characterized by a higher body mass index (BMI), higher basal insulin values and significantly lower cGMP values. Only the group without IR (n=10) developed significant improvement of systolic blood pressure. CONCLUSION: We conclude that blood pressure reduction by treatment of RAS does not alter insulin action and that there is no link between the circulating concentrations of renin/aldosterone and glucose metabolism in renovascular hypertension (RVH). The results do not support the hypothesis of a direct link between blood pressure in RVH and the individual state of insulin sensitivity. However, patients with a normal SI are more likely to experience an almost normalization of arterial blood pressure after treatment for RAS.

Hemodynamically relevant hematuria several months after biopsy of a kidney graft: an unusual cause.

We report the case of a 52-year-old female patient, who after a complicated living donor kidney transplantation, underwent kidney biopsy for suspected rejection. Duplex scanning revealed a small, asymptomatic arteriovenous (AV) fistula which was assessed as being hemodynamically unimportant. During follow-up, several urinary tract infections occurred and recurrent short episodes of hematuria were attributed to cystitis, urethritis and urosepsis. Eight months later, the patient developed suddenly massive hematuria, tamponade of the urinary bladder and hemorrhagic shock as well as urosepsis. Duplex sonography showed a massive pseudoaneurysm in addition to the AV fistula. Arteriography confirmed the Duplex sonographic findings and embolization was performed after treatment of concomitant urosepsis. The fistula was closed completely and bleeding ceased. Although AV fistulas are rare complications of kidney biopsies and in most cases they remain asymptomatic, life-threatening hematuria can present several months after a biopsy due to the development of a pseudoaneurysm. Concomitant infectious complications of the urinary tract, bleeding disorders and other factors can be misleading during the assessment of the cause of gross hematuria. Regular Duplex sonographic follow-up examinations in patients with AV fistulas are advisable.

[Aortoiliac reconstruction after kidney transplantation. Strategies to avoid ischemic damage of the transplant]. / Rekonstruktion der aortoiliakalen Strombahn bei Patienten nach Nierentransplantation. Strategien zur Vermeidung einer ischämischen Transplantatschädigung.

INTRODUCTION: The rising life expectancy of patients undergoing kidney transplantation and the improvement in the function rate of the allografts have led to an increasing number of patients suffering from arteriosclerosis-related diseases of the aortoiliac arteries. In these particular cases, an interruption of the blood supply of the allograft is always necessary for operative repair of the aortic and iliac arteries. This means a high risk of ischemic damage to the transplanted kidney. PATIENTS AND METHODS: Between 1987 and 2000, 1,076 kidney transplantations were performed in our department. During this time, 14 reconstructive operations of the aortoiliac arteries were performed in 12 patients (6 women, 6 men, average age 55.2 (45-71) years). Operations were indicated in patients suffering from occlusive disease with imminent extremity or allograft loss, and symptomatic or asymptomatic aneurysms with a maximum diameter of more than 4 cm. In patients presenting with thoracoabdominal (1) and abdominal aortic aneurysms (3), protection of the transplanted kidney was performed by axilloiliac or axillofemoral bypass. Hypothermic flush-perfusion of the allograft containing PGE1 and heparin was performed in seven of nine operations for occlusive disease. RESULTS: None of the patients presented with a permanent decrease in kidney function, six patients showed temporary creatinine elevation, and in nine patients creatinine levels at discharge were lower than they were preoperatively. None of the patients died. CONCLUSION: Reviewing all reported methods of allograft protection, we recommend a three-step strategy including sequential clamp technique (ischemia < 30 min.), hypothermic flush-perfusion (ischemia < or = 60 min.), and temporary axilloiliac/femoral shunt (ischemia > 60 min), depending on the expected renal ischemia time.

Noninvasive investigation for renal artery stenosis: contrast-enhanced magnetic resonance angiography and color Doppler sonography as compared to digital subtraction angiography.

INTRODUCTION: The question about the most appropriate non-invasive method for detecting a renal artery stenosis (RAS) when comparing contrast enhanced magnetic resonance angiography (MRA) and color Doppler sonography (CDS) is still under discussion. Therefore we conducted a prospective study in order to evaluate both methods as compared to digital subtraction angiography (DSA). PATIENTS/METHODS: Thirtysix consecutive patients (53,9 +/- 13,7 years) with suspected RAS were investigated. MRA was performed using gadolinium for contrast enhancement. CDS was performed using a 2.5 and 3,5 MHz transducer. A peak systolic velocity (Vmax) >200 cm/sec within renal arteries and/or a side to side difference of the resistive index (RI) of >0,05 were used to discriminate stenosis. A diameter reduction of > or = 60% by DSA was considered a stenosis relevant to the patient. RESULTS: Sixty-eight main renal arteries and 9 accessory vessels were detected by DSA. Twenty main and 3 accessory arteries were found to be stenosed > or = 60%, while 4 main and 1 accessory artery presented with occlusion. MRA detected 70 renal vessels (65 main and 5 accessory arteries). Twenty-one stenosed arteries and 4 occluded vessels were correctly diagnosed by MRA. With CDS 68 renal vessels (62 main and 6 accessory arteries) could be visual- ized out of which 21 stenoses were diagnosed because of increased Vmax and 6 stenoses were detected because of a side to side difference of RI. For main renal arteries sensitivities and specificities were 96% and 86% for MRA and 96% and 89% for CDS. CONCLUSIONS: MRA and CDS are both comparable methods for detection of a renal artery stenosis > or = 60%. Despite several limitations, CDS can at the moment still be favored as a screening method.

Systemic mycophenolate mofetil in comparison with systemic cyclosporin A in high-risk keratoplasty patients: 3 years' results of a randomized prospective clinical trial.

BACKGROUND: With the use of systemic cyclosporin A (CsA), graft prognosis after high-risk penetrating keratoplasty has improved considerably. However, the application of CsA is limited owing to a variety of severe side effects. In this prospectively randomized study mycophenolate mofetil (MMF), a safe and efficient immunosuppressive medication after renal transplantation, was compared with CsA after high-risk penetrating keratoplasty. METHODS: Twenty-nine high-risk keratoplasty patients were treated with MMF 2x 1 g daily; another 27 patients received CsA, aiming at blood trough levels of 120-150 ng/ml. Systemic immunosuppression was scheduled for 6 months. In both groups oral corticosteroids (fluocortolone 1 mg/kg) were administered for 3 weeks postoperatively. RESULTS: During the first year after operation, no graft failure was recorded. Two years postoperatively 92%/82% and 3 years postoperatively 74%/69% of grafts were clear in the MMF and CsA group, respectively (Kaplan Meier P=0.33, logrank test). In total, two graft failures were recorded in the MMF group and four in the CsA group. Three years postoperatively 53% of the grafts were rejection-free in the MMF group and 73% in the CsA group (Kaplan Meier P=0.46, log-rank test). Eight endothelial immune reactions were observed in the MMF group (three under systemic immunosuppression/five thereafter; six mild/two severe) and five in the CsA group (three under systemic immunosuppression/two thereafter; three mild/two severe). Side effects occurred in six patients under MMF and 11 under CsA. CONCLUSIONS: Concerning efficacy, no statistically significant difference between systemic MMF and systemic CsA administered for 6 months after high-risk penetrating keratoplasty could be shown. Systemic MMF was proven to be at least as safe as CsA. The main mechanism in improving graft survival is a shift from severe to milder endothelial immune reactions, as already demonstrated for CsA. Thus, MMF may become an alternative to CsA for immunosuppression after penetrating high-risk keratoplasty. About 2 years postoperatively, pharmacologically induced relative immunological tolerance slowly decreases. Therefore, long-term administration of systemic MMF should be evaluated in further studies.

[Highly active antiviral and immunosuppressive combination therapy with acyclovir and mycophenolate mofetil following keratoplasty in patients with herpetic eye disease]. / Hochaktive antivirale und immunsuppressive Kombinationstherapie mit Acyclovir und Mycophenolatmofetil nach Keratoplastic bei herpetischer grunderkrankung.

BACKGROUND: Herpes simplex virus (HSV) infection is the most common cause of corneal blindness in developed countries. Penetrating keratoplasty is the only therapeutic option for visual rehabilitation in patients with severely scarred corneas. Recurrence of the underlying disease and allograft rejection (AR) are the common causes of graft failure. Systemic immuno-suppression with cyclosporin A is contraindicated due to the risk of HSV recurrence. The potent immunosuppressive properties of mycophenolate mofetil (MMF) have already been shown clinically. By reducing the intracellular guanosid-pool MMF inhibits the proliferation of lymphocytes. As these quanosin-nucleosides also act as competing substrates to acyclovir at the viral DNA-polymerase, a synergistic effect of MMF and acyclovir might be expected. The aim of this study was to evalute the efficacy and safety of a double-drug regimen with MMF and acyclovir in the prevention of acute allograft rejection and HSV recurrence following corneal transplantation. METHODS: Patients following penetrating keratoplasty due to herpetic eye disease have been treated with MMF 1 g twice dialy and acyclovir 5 x 200 mg/day for one year. Primary efficacy variables have been the number of acute AR and recurrence of herpetic disease per patient and time. The number of adverse events has been documented for safety analysis. RESULTS: Fifteen patients have been enrolled. The average follow up period was 9.1 (+/- 5.2) months. No graft opacifications have been seen. With two AR and no recurrence of herpetic disease the efficacy ofthis therapeutic regimen was supperior compared with historical control groups. CONCLUSION: In this first study on the efficacy and safety of a double drum regimen with acyclovir and MMF for the control of acute corneal AR and HSV-recurrenct following keratoplasty in patients with herpetic eye disease, the combination therapy has been shown to be a safe and highly efficient protocol for graft protection.

Assessment of radiocontrast media induced renal vasoconstriction by color coded duplex sonography.

INTRODUCTION: Changes in renal hemodynamics are suspected to be one of the major pathogenetic correlates in radiocontrast media-induced nephrotoxicity. We investigated whether color-coded duplex sonography is an appropriate method to document changes in intrarenal vascular resistance, after intravenous injection of the low-osmolar contrast material lopamidol. METHODS: Intrarenal arterial doppler wave forms were analyzed every minute after intravenous injection of 100 mL lopamidol in 10 patients during a voiding cystourogram-procedure. The Resistive Index (RI) of each flow curve, reflecting intrarenal flow resistance, was calculated and compared to the mean of four RI measurements taken before contrast media application. RESULTS: One minute after injection of Iopamidol the RI remained unchanged compared to the baseline standard of 0.70. In measurements obtained 2, 3, 4, and 5 minutes after lopamidol injection a statistically significant rise was seen: (minute 2: 0.74, p < 0.001/minute 3: 0.75, p = 0.001/minute 4: 0.72, p =0.018/minute 5: 0.74, p = 0.031). During the further course, the resistive indices decreased progressively and showed no significant difference in comparison with the baseline standard value. CONCLUSION: Color coded duplex sonography is a simple method to detect changes in renal flow resistance after application of radiocontrast media. Based on our results, we believe that the analysis of intrarenal arterial doppler flow profiles constitutes an ideal method to investigate pathophysiologic mechanisms of radiocontrast media-induced nephrotoxicity, as well as pharmacological concepts in nephroprotectivity.