Markus Hollenbeck

Management of arterial stenosis affecting kidney graft perfusion: a single-centre study in 53 patients.

We assessed clinical and duplex sonographic (CDS) findings, and outcome in patients with stenosis of the transplant renal artery (TRAS) or the aorto‐iliac segment proximal to the graft (Prox‐TRAS) treated with dilatation (PTA), stenting (PTAS) and surgery. From 1988 to 2002, of 1189 patients with renal transplantations, 117 underwent angiography. Fifty‐three patients with TRAS (n = 37)/Prox‐TRAS (n = 16) were found (4.4%).

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 ≥60% by DSA was considered a stenosis relevant to the patient. Results: Sixtyeight main renal arteries and 9 accessory vessels were detected by DSA. Twenty main and 3 accessory arteries were found to be stenosed ≥60%, while 4 main and 1 accessory artery presented with occlusion. MRA detected 70 renal vessels (65 main and 5 accessory arteries). Twentyone stenosed arteries and 4 occluded vessels were correctly diagnosed by MRA. With CDS 68 renal vessels (62 main and 6 accessory arteries) could be visualized 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 ≥60%. Despite several limitations, CDS can at the moment still be favored as a screening method.

Iliac artery stenosis proximal to a kidney transplant: Clinical findings, duplex-sonographic criteria, treatment, and outcome

Background. Stenosis of the iliac segment proximal to the transplant renal artery (Prox-TRAS) is an uncommon cause of graft dysfunction and hypertension. We assessed the role of duplex sonography (DS) in regard to clinical and angiographic findings and followed the patients after percutaneous transluminal angioplasty (PTA), PTA stenting (PTAS), or surgery. Methods. From January 1988 to August 2001, 97 of 1,064 kidney recipients underwent angiography for clinical or Doppler-sonographic suspicion of vascular problems. Kidney function, blood pressure, medication, and DS findings after renal transplantation (RTx) at the time of diagnosis of Prox-TRAS and after treatment were evaluated. Results. Prox-TRAS was diagnosed in 16 patients (1.5%) (49.6±6.9 years). Four patients demonstrated early presentation of Prox-TRAS 1 to 7 days after RTx (group A), leading to acute renal failure but without hypertension. In all patients, DS revealed pulsus parvus et tardus, low pulsatility index (PI) (<1.0), and a pathologic flow profile in the iliac artery proximal and distal to the graft. After treatment (surgery in two patients, PTA in one patient, PTAS in one patient), all patients developed good renal function (creatinine 1.7±0.9 mg/dL). PI increased from 0.9±0.1 to 1.2±0.1 (P =0.04), and flow profile within the iliac artery distal to the graft normalized. Late presentation (3–209 months after RTx) of Prox-TRAS was observed in 12 patients (group B), causing an increase of creatinine in 11 patients (two patients receiving dialysis treatments), impairment of blood pressure (141±15 and 80.7±7 to 160±18 and 85±7 mm Hg, P =0.009), and an increase in antihypertensive drugs (2.1±1.1 and 4.3±1, P =0.003) in all patients. The PI was decreased when compared with values early after RTx (1.6±0.4 to 1.2±0.3, P =0.007), and flow profile in the iliac artery was pathologic. All patients except one were managed by surgery (n=6), PTA (n=1), or PTAS (n=4). Creatinine (2.7±1.4 to 1.8±0.4 mg/dL, P =0.02) and blood pressure (160±18/85±7 mm Hg to 138±7/82±9, P =0.018) improved. Antihypertensive drugs were reduced to 2.8±0.8 (P =0.01). PI increased from 1.2±0.3 to 1.9±0.5 (P =0.01). Flow profile within the iliac artery distal to the graft anastomosis normalized. Kidney function, blood pressure, and PI remained unchanged during follow-up (82±69.9 months) in both groups. Conclusions. Prox-TRAS is rare. Because clinical symptoms are similar to those of transplant renal artery stenosis, DS is a valuable tool for diagnosis and follow-up for this type of vascular lesion. Selective treatment with PTA, PTAS, or surgery improves kidney function and hypertension.

Kidney transplantation in the elderly: age-matching as compared to HLA-matching: a single center experience.

Background. We report the short-term outcome of our patients participating within the Eurotransplant age-matching program, where kidneys from donors >65 years are transplanted to recipients >65 years regardless of human leukocyte antigen (HLA) compatibility but with short cold ischemia times, in comparison with patients >60 years transplanted with HLA-matching. Methods. Twenty-five patients (66.7±2.6 years) (donors 69±4.3 years) participated in this program (group A). The control group consisted of 21 patients (63±2.6 years) (group B) (donors 47.6±17.3 years). Results. Despite significant differences in donor age, cold ischemia time (12.3±4.6 hr in A, 22.8±4.8 hr in B, P <0.001) and a mean of 4.4±1.4 vs. 2.3±1.6 HLA-mismatches (P <0.001), there was no difference regarding the incidence of delayed graft function (64 vs. 57%), rejections (52 vs. 66.7%), infections (56 vs. 52.4%), and other complications (80 vs. 71.4%). Mean serum creatinine after 6 months was 1.94±0.49 and 1.83±0.67 mg/dl (NS). Conclusion. The short-term results of the age-matching program are promising and comparable with results from patients of similar age with HLA-matching.

Increasing sensitivity and specificity of Doppler sonographic detection of renal transplant rejection with serial investigation technique.

Acute rejection episodes are the most common cause leading to loss of renal grafts in the early postoperative phase. Doppler sonography presents a noninvasive tool to detect increased arterial blood flow resistance as a result of rejection. This can be measured by the increase in the resistive index (RI) and the pulsatility index (PI). In a prospective study including 65 consecutive patients we investigated whether the detection of rejection episodes is improved by determining RI or PI serially twice a week instead of performing a single examination in cases of transplant dysfunction. In 330 examinations with a color-coded Doppler device (Philips QAD 1, Philips Medical Systems Hamburg, Germany) flow profiles were obtained by means of pulse-wave Doppler over at least three interlobar arteries of the renal transplant and RI and PI were calculated. In 41 cases primary rejections were better recognized by an increase in PI compared to the preceding value than by the absolute PI value (with a sensitivity of 90%; specificity was 76% and 42% respectively). The RI was less specific (with a sensitivity of 90%; specificity was 47% for the relative RI increase and 30% for the absolute RI value). The continuous PI increase started an average of 3.3 days (95% CI −15.25 to + 1.55) before rejection was diagnosed. Vascular rejection episodes showed higher PI values than interstitial rejections (3.86 ± 2.14 vs. 2.19 ± 0.87; P < 0.01). The serial investigation technique of PI allows better recognition of rejection episodes than the single measurement of RI or PI performed so far. Doppler sonography recognizes rejection at an early stage.

Development of Insulin Resistance and Elevated Blood Pressure during Therapy with Cyclosporine A

OBJECTIVES Essential hypertension and insulin resistance frequently coexist; cyclosporine A (CsA) is known to induce hypertension which has been used as a model for essential hypertension. The present study aimed to evaluate whether elevated blood pressure and insulin resistance coexist during CsA therapy to prove the similarity between essential hypertension and CsA induced hypertension. DESIGN Normotensive patients who underwent keratoplasty were investigated before and during single therapy with CsA (2-4 mg/kg body weight) in an open A-B Trial. PATIENTS Eighteen lean, normotensive patients without metabolic disorders with normal renal function and without family history of hypertension or metabolic abnormalities. MAIN METHODS Insulin sensitivity index was determined by the modified frequent sampling intravenous glucose tolerance test (FSIGT) and blood pressure was determined by indirect ambulatory blood pressure monitoring. RESULTS Mean insulin sensitivity index (S1) was significantly reduced (p < 0.03) during treatment with CsA (4.4 +/- 2.6 x 10(-4) vs 2.8 +/- 2.0 x 10(-4)/min per microU/ml), whereas mean systolic daytime blood pressure increased from 126.4 +/- 10.8 mmHg to 135.7 +/- 11.8 mmHg (p < 0.02), as well as the corresponding diastolic blood pressure from 76.8 +/- 8.7 mmHg to 82.8 +/- 9.3 mmHg (p < 0.05). CONCLUSIONS CsA therapy induces elevated blood pressure and insulin resistance as seen in patients with essential hypertension, thus CsA induced hypertension is considered to have pathophysiological similarities to essential hypertension.

Percutaneous renal biopsy: three years of experience with the biopty gun in 761 cases--a survey of results and complications.

From 1.1.1993 to 12.31.1995 we performed 761 consecutive biopsies on 509 non-selected patients. The most frequent diagnoses in 351 biopsies (39.4%) on native kidneys were 262 cases of glomerulonephritis (74.6%) and 167 of so-called benign nephrosclerosis (47.6%). With 410 biopsies (60.6%) on allograft kidneys 219 cases (78%) showed signs of interstitial rejection, 14 cases (5%) vascular and 49 cases (17%) interstitial as well as vascular rejection. Only after 5 biopsies (0.66%) clinical relevant complications (3 perirenal haematomas, 1 AV fistula, 1 vesical tamponade) appeared. Again percutaneous renal biopsy is proven to be a diagnostically efficient and safe tool at the same time even when used in a large number of non-selected patients, so that an ambulant performance may be discussed. The relatively frequent diagnosis of a so-called benign nephrosclerosis seems to indicate the need for an intensified examination of this disease.

Assessment of radiocontrast media induced renal vasoconstriction by color coded duplexsonography

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 Iopamidol. Methods: Intrarenal arterial doppler wave forms were analyzed every minute after intravenous injection of 100 mL Iopamidol 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 Iopamidol 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.

Influence of betaxolol on renal function and atrial natriuretic peptide in essential hypertension.

The hypotensive action of beta-adrenoreceptor blockers is not fully understood, there being a lack of studies focusing on possible relationships between beta-blockers and the secretion of atrial natriuretic peptide (ANP). In 10 patients with essential hypertension, we investigated the influence of betaxolol, a selective beta 1-adrenergic blocking agent, on renal function and on plasma levels of ANP during exercise, volume depletion and volume expansion. Chronic therapy with betaxolol (mean 14.5 mg/day) did not alter glomerular filtration rate and renal blood flow although blood pressure was reduced. Renal vascular resistance decreased from 12795 +/- 1064 dyn/s per cm5 to 10614 +/- 833 dyn/s per cm5 (P less than 0.005). Under betaxolol, basal ANP levels increased from 39 +/- 10 pg/ml to 80 +/- 19pg/ml (P less than 0.01). ANP increased during exercise and volume expansion but was decreased during volume depletion. ANP values observed under betaxolol treatment showed significantly higher values while preserving their dynamic features. We believe that the stimulating effect of betaxolol on ANP may at least partly account for its hypotensive action.

Indicators of acute and persistent renal damage in adult thrombotic microangiopathy.

Background Thrombotic microangiopathies (TMA) in adults such as thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS) are life-threatening disorders if untreated. Clinical presentation is highly variable and prognostic factors for clinical course and outcome are not well established. Methods We performed a retrospective observational study of 62 patients with TMA, 22 males and 40 females aged 16 to 76 years, treated with plasma exchange at one center to identify clinical risk factors for the development of renal insufficiency. Results On admission, 39 of 62 patients (63%) had acute renal failure (ARF) with 32 patients (52%) requiring dialysis treatment. High systolic arterial pressure (SAP, p = 0.009) or mean arterial pressure (MAP, p = 0.027) on admission was associated with acute renal failure. Patients with SAP>140 mmHg on admission had a sevenfold increased risk of severe kidney disease (OR 7.464, CI 2.097–26.565). MAP>100 mmHg indicated a fourfold increased risk for acute renal failure (OR 4.261, CI 1.400–12.972). High SAP, diastolic arterial pressure (DAP), and MAP on admission were also independent risk factors for persistent renal insufficiency with the strongest correlation for high MAP. Moreover, a high C-reactive protein (CRP) level on admission correlated with renal failure in the course of the disease (p = 0.003). At discharge, renal function in 11 of 39 patients (28%) had fully recovered, 14 patients (23%) remained on dialysis, and 14 patients (23%) had non-dialysis-dependent chronic kidney disease. Seven patients (11%) died. We identified an older age as risk factor for death. Conclusions High blood pressure as well as high CRP serum levels on admission are associated with renal insufficiency in TMA. High blood pressure on admission is also a strong predictor of sustained renal insufficiency. Thus, adult TMA patients with high blood pressure may require special attention to prevent persistent renal failure.