Captopril renography and duplex Doppler sonography in the diagnosis of renovascular hypertension

Background. The purpose of this prospective study was to determine the clinical usefulness of captopril renal scintigraphy and duplex Doppler sonography in detecting haemodynamically significant renal artery stenosis (⩾60%) and predicting cure or improvement of hypertension following revascularisation. Methods. Twenty-eight patients with moderate or high index of clinical suspicion of renovascular hypertension underwent both captopril renal scintigraphy and duplex Doppler sonography before undergoing renal angiography. Patients with angiographically proved (⩾60%) RAS were treated by percutaneous transluminal renal angioplasty unless it was contraindicated. Results. The results of captopril renal scintigraphy and duplex Doppler sonography were compared by renal angiography of 45 renal arteries in 28 patients. Eleven renal arteries were excluded from further comparison, because no accurate Doppler signal could be obtained. The sensitivity and specificity of captopril renal scintigraphy in the identification of RAS (⩾60%) was 78% and 81% respectively. The sensitivity of duplex Doppler sonography was 83% and the specificity was 81%. Positive predictive values of both tests for blood pressure cure or improvement after PTRA were 86% for CRS and 85% for DDS. Conclusions. Captopril renal scintigraphy and duplex Doppler sonography are comparable tests for detection of patients with haemodynamically significant renal artery stenosis (⩾60%). Positive predictive values of both tests for cure or improvement of hypertension after percutaneous transluminal renal angioplasty are good and comparable.     

Renal artery stenosis: evaluation with colour duplex ultrasonography

Background: Detection of renal artery stenoses (RAS) by means of duplex Doppler ultrasound with direct scanning of the main renal arteries is subject to numerous limitations. Using semiquantitative analysis of the Doppler curve, which can be recorded from intrarenal arteries, it is possible to detect RAs unaffected by the problems of direct Doppler scanning of the renal arteries. Method: Both angiography of the renal arteries and colour duplex ultrasonography (US) of the intrarenal vessels (interlobar arteries) were performed in 214 patients (53.2±15.1 years) with severe arterial hypertension. Angiography was used as 'gold standard' in the diagnosis of RAS and the Doppler results were compared with the subsequent findings on angiography. At angiography, the reduction of diameter >70% was assessed as haemodynamically effective RAS. For the duplex Doppler diagnosis of RAS the following parameters were calculated: (a) resistive index (RI) of each kidney, and (b) side-to-side differences of the resistive indices (&Dgr;RI) between the right and left kidney. Results: Angiography demonstrated 59 RAS (>70%) in 53 patients, including six with bilateral RAS. By means of duplex US we found a significant difference of RI between kidneys with RAS (0.48±0.11) and without RAS (0.63±0.08; P<0.001). In addition, a significant difference of the &Dgr;RI was noted in patients with RAS (24.4%±12.5%) and the controls without RAS (3.6%±2.7%). Using a combination of both RI and &Dgr;RI, threshold values of RI=0.45 resp. &Dgr;RI=8% yields a sensitivity of 92.5% and a specificity of 95.7% in the detection of haemodynamically effective RAS. Conclusion: Colour duplex US with calculation of the RI and &Dgr;RI of intrarenal arteries is a valuable non-invasive test assessing the haemodynamic effects of RAS. Low costs and safety support the use of the Doppler technique in screening for renovascular disease.     

A correlation between direct and indirect Doppler ultrasonographic measures in transplant renal artery stenosis

Screening for transplant renal artery stenosis (TRAS) with Doppler ultrasonography (DUS) is increasingly used in the era of kidney transplantation. Direct Doppler study of the stenotic site is a time- consuming and difficult method that requires an angle of interrogation parallel to the vessel. The aim of this study was to assess the correlation between the direct-PSVs (peak systolic velocity at the stenotic site), PSVs/PSVi (PSVi, peak systolic velocity of the adjacent iliac artery)-and indirect-intrarenal arterial resistive index (RI), perfusion index (PI), acceleration time (AT)-DUS findings in the kidney transplant recipients with TRAS. We performed 26 DUS studies of both intrarenal and main renal arteries in 19 TRAS patients (who had PSVs > 150 cm/s, PSVs/PSVi > 2). The mean values of PSVs and PSVs/PSVi were 212 +/- 44.19 cm/s and 2.77 +/- 0.77, respectively. The mean intrarenal RI, PI, and AT were 0.48 +/- 0.065, 0.70 +/- 0.12, and 177.8 +/- 54.6 msec, respectively. A significant negative correlation was found between PSVs and intrarenal RI (Pearson correlation coefficient (r) = -0.4, two-tailed P = .043). No correlation was found between intrarenal PI or AT and the direct DUS findings (P > .05). With a cutoff level of 0.55 for intrarenal resistive index, the sensitivity of this parameter to detect proximal renal arterial stenosis was about 85%. Conclusively, PSVs and intrarenal RI were negatively correlated. Intrarenal resistive index can be used as an screening measure for detection of TRAS.     

Intraoperative duplex sonography during renal artery reconstruction

To assess renal duplex sonography as an intraoperative study to detect technical defects during repair, 57 renal artery reconstructions in 35 patients were studied. Sixteen men and 19 women (mean age, 62 years) underwent unilateral (13 patients) or bilateral (22 patients) renal artery repair to 57 kidneys. Methods of repair included aortorenal bypass grafting in 29 cases (20 saphenous vein, 5 polytetrafluoroethylene, 4 Dacron), reimplantation in 7, transrenal thromboendarterectomy with patch angioplasty in 13, and transaortic extraction thromboendarterectomy in 8. Branch renal artery repair was required in six cases (five in vivo, one ex vivo). Fourteen patients had combined aortic replacement (11 patients: 8 abdominal aortic aneurysms, 3 aortic occlusions) or visceral artery reconstruction (three patients: three superior mesenteric artery thromboendarterectomies, one inferior mesenteric artery thromboendarterectomy). Intraoperative renal duplex sonography (mean scan time, 4.5 minutes) was complete in 56 of 57 repairs (98%), and renal duplex sonography was normal in 44 repairs (77%). Overall, B-scan defects were present in 13 repairs (23%). Six of these (11%) were defined as major B-scan defects by Doppler spectra with focal increases in peak systolic velocity greater than or equal to 2.0 meters/sec (major defect, mean renal artery peak systolic velocity, 3.1 m/sec), which prompted immediate operative revision. Seven B-scan defects were defined as minor by Doppler spectra (minor defect, mean renal artery, peak systolic velocity, 0.7 m/sec) and were not revised. Postoperative evaluation (range, 1 to 22 months; mean follow-up, 12.4 months) of 55 renal artery repairs in 34 operative survivors (surface renal duplex sonography, 33 patients; renal angiography, 9 patients) demonstrated 42/43 renal artery repairs with normal intraoperative renal duplex sonography, and 6/6 repairs with minor B-scan defects were patent and free of critical stenosis. Of the 6 renal artery revisions prompted by major B-scan defects, 4 remained patent, 1 stenosed, and 1 occluded. Our experience suggests that intraoperative renal duplex sonography during renal artery repair provides valuable anatomic and physiologic information. Renal artery repairs with normal renal duplex sonography and minor B-scan defects without Doppler spectral changes demonstrated 98% patency without critical stenosis at 12.4 months of mean follow-up. However, major B-scan defects defined by a focal increase in renal artery peak systolic velocity should be considered for immediate correction.     

How to limit screening of patients for atheromatous renal artery stenosis in two-drug resistant hypertension?

BACKGROUND: The DRASTIC model based on nine variables (age, gender, recent onset of hypertension, smoking status, body mass index (BMI), abdominal bruit, atherosclerosis, dyslipidemia and creatininemia) has been proposed to predict renal artery stenosis (RAS) occurrence. METHODS: In a prospective multicenter study, the clinical usefulness of the DRASTIC model was checked in 336 patients with two-drug resistant hypertension. RAS was excluded using at least color Doppler sonography. RAS was diagnosed using at least renal angiography. The statistical dependence (Z(Rho)) analysis was applied to investigate further the relationships between each variable and presence of RAS. Results: The prevalence of RAS (n=51) was 15%. The goodness-of-fit test that compared observed RAS to predicted RAS using the DRASTIC model was not significant. Accordingly, the multivariate logistic regression indicated that only three parameters (abdominal bruit, atherosclerotic vascular disease and BMI <25 kg/m2) were significantly linked to RAS. The Z(Rho) methodology revealed that calculated renal function <60 ml/min and age >58 yrs (median) were also significantly linked to RAS. No variable or combination of variables offered satisfactory positive predictive values for the RAS diagnosis. The combination of the five significantly linked variables had a negative predictive value of 98%, and allowed RAS detection with a sensitivity of 96%. In our population, RAS screening could have been avoided in 30% of our patients screened. CONCLUSIONS: The DRASTIC model was unsuitable for clinical use in our sample population. In our population, renal arteries were considered stenosis free with a probability of 98% in refractory hypertensive overweight patients, aged < or = 58 yrs, with satisfactory renal function and without both abdominal bruit and atherosclerotic vascular disease.     

Noninvasive diagnosis of renal artery stenosis by echo-Doppler velocimetry

We evaluated the diagnostic accuracy of ultrasonic echo-Doppler velocimetry for the noninvasive diagnosis of renal artery stenosis. Renal artery stenosis was diagnosed if one or more of the following four abnormal hemodynamic parameters were found by Doppler velocimetry: (1) peak blood velocity greater than 100 cm . sec-1 in a focal area along the length of a renal artery, (2) absence of blood velocity during diastole, (3) absence of any detectable blood velocity denoting occlusion, or (4) broad-band Doppler frequency spectra due to focal blood velocity disturbances. With these criteria, the presence or absence of renal artery stenosis was blindly evaluated in 26 patients (52 arteries) who underwent standard or digital subtraction angiography. Compared to arteriography (reduction in diameter greater than or equal to 50%), the sensitivity of Doppler method was 89%, while its specificity was 73%. This noninvasive method may be useful in selecting patients for radiographic evaluation of renal artery stenosis and in the long term follow-up of these patients. Furthermore, echo-Doppler velocimetry may have the unique capability of assessing the hemodynamic consequences of renal artery stenosis.     

Value of Doppler ultrasound for the diagnosis of renal artery stenosis in children

To evaluate the reliability of Doppler ultrasonography (US) in identifying children with renal artery stenosis (RAS) among those with hypertension, we compared Doppler US results in 22 hypertensive children (mean age 8.9±4.3 years), with (13 cases) and without RAS at angiography, and in 33 normotensive children (mean age 8.8±4.7 years). We observed 2 false-negatives and 2 false-positives with Doppler US. Of the 2 false-negative diagnoses, 1 had RAS on an accessory renal artery located behind a normal upper polar artery and the other was observed in a patient with bilateral multiple stenosis of the very distal segments of renal arteries. The 2 false-positive diagnoses were due to sinuous left renal artery and to technical reasons, respectively. In another patient, Doppler US showed a tight RAS, while arteriography was normal. RAS was subsequently confirmed by a second arteriography. Peak systolic velocity values of Doppler US were significantly higher in patients with proven angiographic RAS (3.44±0.66 m/s) than in hypertensive patients with normal renal arteries at angiography (0.99±0.35 m/s, P <0.0001) and normotensive healthy children (1.04±0.23 m/s, P <0.0001). With the use of multiple views, and the experience acquired with practice, false-negatives or false-positives due to the geometry of the renal artery can be avoided. Nevertheless, very distal stenosis can be missed by Doppler US. Received October 30, 1995; received in revised form April 16, 1996; accepted May 14, 1996     

Imaging modalities for renal artery stenosis in suspected renovascular hypertension: prospective intraindividual comparison of color Doppler US, CT angiography, GD-enhanced MR angiography, and digital substraction angiography

The aim of the study was to evaluate the diagnostic accuracy of Color Doppler US, CT Angiography (CTA), and GD-enhanced MR Angiography (MRA) compared with digital subtraction angiography (DSA) for the detection of renal artery stenosis in patients with clinically suspected renovascular hypertension. Fifty-eight patients with suspected renovascular hypertension were enrolled in the study. All patients underwent Color Doppler US, CTA and GD-enhanced MRA. DSA was the gold standard method for the number of renal arteries, existence and degree of stenosis, or evidence of fibromuscular dysplasia. DSA depicted 132 renal arteries, 16 stenoses, and 4 arteries with fibromuscular dysplasia. Color Doppler US failed to detect 1 main and 14 polar arteries. CTA depicted all main renal arteries and 7/16 polar arteries, but failed to detect stenosis in two accessory vessels. Likewise, MRA did not detect stenotic accessory renal arteries, depicted 9/16 polar renal arteries, but missed two main renal arteries. All methods depicted the four main renal arteries with fibromuscular dysplasia. The overall sensitivity, specificity, and positive and negative predictive accuracy were 75%, 89.6%, 60% and 94.6%, respectively, for color Doppler US; 94%, 93%, 71%, and 99%, respectively, for CTA; and 90%, 94.1%, 75%, and 98%, respectively, for GD-enhanced MRA. CTA and GD-enhanced MRA have comparable and satisfactory results with respect to the negative predictive accuracy of the suspected renal artery stenosis. The concept of an imaging algorithm including US as screening test when appropriate and CTA or MRA as the second step-procedure is suggested. Therefore, DSA may be reserved for cases with major discrepancies or therapeutic interventions.     

Imaging Modalities for Renal Artery Stenosis in Suspected Renovascular Hypertension: Prospective Intraindividual Comparison of Color Doppler US,CT Angiography,GD-Enhanced MR Angiography,and Digital Substraction Angiography

The aim of the study was to evaluate the diagnostic accuracy of Color Doppler US, CT Angiography (CTA), and GD-enhanced MR Angiography (MRA) compared with digital subtraction angiography (DSA) for the detection of renal artery stenosis in patients with clinically suspected renovascular hypertension. Fifty-eight patients with suspected renovascular hypertension were enrolled in the study. All patients underwent Color Doppler US, CTA and GD-enhanced MRA. DSA was the gold standard method for the number of renal arteries, existence and degree of stenosis, or evidence of fibromuscular dysplasia. DSA depicted 132 renal arteries, 16 stenoses, and 4 arteries with fibromuscular dysplasia. Color Doppler US failed to detect 1 main and 14 polar arteries. CTA depicted all main renal arteries and 7/16 polar arteries, but failed to detect stenosis in two accessory vessels. Likewise, MRA did not detect stenotic accessory renal arteries, depicted 9/16 polar renal arteries, but missed two main renal arteries. All methods depicted the four main renal arteries with fibromuscular dysplasia. The overall sensitivity, specificity, and positive and negative predictive accuracy were 75%, 89.6%, 60% and 94.6%, respectively, for color Doppler US; 94%, 93%, 71%, and 99%, respectively, for CTA; and 90%, 94.1%, 75%, and 98%, respectively, for GD-enhanced MRA. CTA and GD-enhanced MRA have comparable and satisfactory results with respect to the negative predictive accuracy of the suspected renal artery stenosis. The concept of an imaging algorithm including US as screening test when appropriate and CTA or MRA as the second step-procedure is suggested. Therefore, DSA may be reserved for cases with major discrepancies or therapeutic interventions.     

Noninvasive evaluation of renal artery stenosis and renovascular resistance. Experimental and clinical studies

Doppler ultrasound was used to detect experimental and clinical renal artery stenosis (RAS) and increased renovascular resistance (RVR). Parameters assessing RAS included elevated systolic frequency and spectral broadening, while diastolic/systolic frequency ratios predicted elevated RVR. In canine models these parameters detected graded RAS before reduction in renal blood flow. Index values were 88% sensitive and 100% specific in identifying RAS with gradients greater than or equal to 25 mm Hg. Diastolic/systolic frequency correlated well with increased RVR induced by microsphere injections (p less than 0.05). Duplex scanning noninvasively detected bilateral renal artery velocity in 113 of 120 patients. Index values were 83% sensitive and 97% specific in identifying greater than or equal to 60% RAS in 86 vessels visualized by angiography. Estimated RVR was significantly higher in age-matched hypertensive and atherosclerotic patients than in controls (p less than 0.01). Ultrasound may be useful to screen patients for RAS and increased RVR.     

Evaluation of blood flow in carotid artery stenosis using B-flow sonography

B-flow ultrasonography can directly visualize blood streams by reflecting the intravascular red blood cells, and so can detect turbulent flow in vessels. B-flow sonography was used to evaluate flow abnormalities in patients with cervical carotid artery stenosis, and to investigate the mechanism of large embolus formation that may cause distal arterial occlusion. Twenty-two patients with > or = 60% stenosis of the cervical carotid artery excluding cardiovascular embolism were examined by B-flow and color Doppler sonography. Two patients had distal embolism as revealed by digital subtraction angiography, 16 patients had lacunar infarction, and four patients had transient ischemic attacks. B-flow sonography demonstrated reverse flow at the poststenotic site in patients with > or = 70% stenosis. Increased echogenicity at the site of the stenosis was seen in patients with at least 80% stenosis. Prestenotic reverse flow was seen in nine patients with > or = 85% stenosis. The two patients with distal embolism had decreased echogenicity and flow velocity, and diastolic flow was absent. B-flow sonography could detect various turbulent flow patterns and changes in echogenicity associated with cervical carotid artery stenosis. Prestenotic reverse flow and decreased flow velocity may be potential causes of distal embolism. B-flow sonography is a useful method for the evaluation of flow abnormality in patients with carotid artery stenosis.     

Incidental renal artery stenosis in peripheral vascular disease: a case for treatment?

BACKGROUND: Renal artery stenosis (RAS) is frequently encountered as an incidental finding in peripheral vascular disease. We assessed whether revascularization is indicated to prevent the practical consequences of end-stage renal failure, that is, the need for renal replacement therapy. METHODS: In a retrospective study, a cohort of consecutive patients was followed who had undergone angiography 8 to 10 years previously for peripheral artery disease. Patients with untreated incidental RAS of > or =50% diameter stenosis (68.8 +/- 9.8 years, mean +/- SD) were compared with regard to the prevalence of renal replacement therapy to controls without RAS who were matched for age and gender. RESULTS: RAS was present in 126 of 386 evaluable patients (33%). None of these patients required renal replacement therapy during the 10-year follow-up. Serum creatinine values remained stable during follow-up. CONCLUSIONS: Incidental RAS is frequently seen in patients with peripheral vascular disease. If left untreated, incidental RAS seems not to result in end-stage renal failure or in a need for renal replacement therapy. Revascularization with the aim to prevent end-stage renal failure seems less indicated, and further prospective studies are indicated to elucidate this issue.     

Posttransplant Renal Monitoring With B-Flow Ultrasonography

B-flow ultrasonography (BFU) is a new technology to detect blood circulation. It has been developed by using digitally encoded sonography, showing higher spatial and temporal resolution than Doppler imaging because of the clearer definition of the vessel lumen. Our study was performed on 55 patients, including 37 men (67.3%) and 18 women (32.7%), of overall mean age of 45.8 years (range = 16-60 who underwent kidney transplantation from deceased donors. The patients underwent an ultrasonography check postoperatively with successive daily controls to compare evaluations with both techniques: the combination of color and power Doppler versus BFU. In 25 patients (45.5%), visualization of cortical blood flow was clearer than with the standard techniques. The parameters of intrarenal circulation were easy to measure. In conclusion, BFU was effective to visualize hemodynamic flow and to detect stenotic lesions in the renal artery. Combined with the conventional B-mode technique, BFU seems to be useful in the evaluation of renal anasthamotic stenosis, especially among patients with vascular diseases.     

糖尿病早期肾损害的彩色多普勒超声研究

目的：探讨彩色多普勒超声肾血流测定对诊断糖尿病早期肾损害的价值。方法：以尿白蛋白排泄率（UAER）作为早期肾损害指标,对60例糖尿病患在26例正常人行彩色多普勒超声肾血流检查,结果：小叶间动脉收缩期峰值流速（Vs),弓状动脉及小叶间动脉舒张末期流速（Vd)的减慢是糖尿病患最早出现的肾内血流动力学改变;有肾脏早期损害的糖尿病患肾血流频谱参数特点是肾内弓状动脉,小叶间动脉的Vs和肾内各分支动脉的Vd明显减低,肾内各分支动脉的阻力指数（RI）明显增高,RI与糖尿病患肾功能损害程度相关。结论：彩色多普勒超声肾血流检测是早期诊断糖悄病肾损害的简便,可靠的方法。     

肾动脉狭窄的介入治疗分析

目的 分析介入治疗肾动脉狭窄（RAS）的疗效。方法自2003年3月至2008年3月共收治45例RAS患者,53支肾动脉中单纯行腔内球囊扩张术（PTA）治疗11支,行球囊扩张及内置支架术（PTA／Stent）治疗者42支,随访9～48个月,检测患者的血压与血肌酐水平,并作肾动脉彩超。结果手术成功率为100％。手术后高血压治愈者9例,改善28例,肾功能改善12例。肌纤维发育不良及多发性大动脉炎的血压改善有效率均为100％,高于动脉粥样硬化的有效率65．1％（P〈0．05）。行彩色多普勒超声检查肾动脉18支,发现再狭窄者7支。结论PTA和PTMStent治疗肾动脉狭窄具有微创、安全、有效的优点。     

A single chinese center investigation of renal artery stenosis in 141 consecutive cases with coronary angiography

BACKGROUND: There is an increasing prevalence of ischemic nephropathy in the aging population of the world. However, the exact incidence of ischemic nephropathy in the Chinese population is still uncertain. The present study investigated the incidence of renal artery stenosis (RAS) in patients with suspected coronary artery disease (CAD) using renal angiography. METHODS: Renal angiography was performed immediately after coronary artery angiography in 141 patients with suspected CAD, including 59 males and 82 females whose mean ages were 59 +/- 10 years. Comorbidities included hypertension (n = 69), diabetes mellitus (n = 21), hyperlipidemia (n = 19), hypokalemia (n = 7) and preoperative renal insufficiency (Cr >132 micromol/l; n = 14). The patients were divided into CAD (luminal narrowing of > or =50%) and non-CAD (luminal narrowing of <50%) subgroups, and RAS (luminal narrowing of > or =50%) and non-RAS subgroups. In the RAS group, there were 11 patients (5 males, 6 females) in whom percutaneous transluminal renal angioplasty was performed in conjunction with stent implantation due to refractory hypertension. RESULTS: The incidence of RAS was 18.4% (26/141) in all cases and 30.8% (16/52) in patients with CAD identified by coronary artery angiography. Ten cases with RAS were found among the 89 cases with normal coronary arteries (11.2%). The incidence of RAS in patients with CAD was higher than that in patients without CAD (30.8 vs. 11.2%, p< 0.05). In 52 cases with CAD, the incidence of RAS with three vessel lesions was significantly higher than that with one or two vessel lesions. Hypertension, CAD, renal insufficiency, hyperlipidemia and hypokalemia were associated with a higher risk of RAS. CONCLUSIONS: This study suggests that RAS is very common in the elderly Chinese population, specifically for those with three vessel lesions in CAD. For early detection of potential ischemic nephropathy, renal angiography is necessary in patients who receive coronary artery angiography.     

Prevalence and prediction of renal artery stenosis in patients with coronary and supraaortic artery atherosclerotic disease.

BACKGROUND: Renal atherosclerosis is associated with increased cardiovascular mortality. This study aimed to determine the prevalence and predictors of renal artery stenosis (RAS) in patients with coronary artery disease (CAD) and supraaortic arteries (SA) stenosis. METHODS: Renal angiography was performed in 1193 (807 men) consecutive patients referred for coronary or SA angiography. Group I included 296 (136 men, 60.1 +/- 9.5 years) patients with no significant (< 50%) lesion in coronary arteries or SA; group II included 706 (526 men, 62.2 +/- 9.7 years) patients with stenosis > or = 50% within single arterial territory (coronary arteries or SA) and group III included 191 (145 men, 64.9 +/- 8.5 years) patients with stenosis > or = 50% in both territories. RESULTS: Some RAS was found in 55 (18.6%) patients in group I, 250 (35.4%) patients in group II and 115 (60.2%) patients in group III (P < 0.001). The proportion of patients with RAS > or = 50% in groups I, II and III was 3.3, 6.2 and 18.3%, respectively (P < 0.001). RAS prevalence increased with the number of stenosed coronary arteries (38.4% in 1-vessel, 42.1% in 2-vessel, 48.5% in 3-vessel CAD, P < 0.001). Independent predictors of RAS > or = 50% identified by logistic regression analysis were SA stenosis [relative risk (RR) = 3.28, P < 0.001], 2-3-vessel-CAD (RR = 2.04, P = 0.002), creatinine level > or = 1.07 mg/dl (RR = 2.95, P < 0.001), hypertension (RR = 2.97, P = 0.012) and body mass index < 25 kg/m(2) (RR = 1.42, P = 0.169). A calculated score for RAS > or = 50% prediction (based on the regression model) was reliable (coefficient of determination, R = 0.978) and showed a sensitivity of 77.5% and a specificity of 63.9%. CONCLUSIONS: RAS prevalence and severity increases with the number of arterial territories involved and CAD severity. The following independent predictors of RAS > or = 50% were identified: SA involvement, 2-3-vessel-CAD, serum creatinine level and hypertension.     

Renal artery stenosis is not associated with the development of acute renal failure following coronary artery bypass grafting

BACKGROUND: Acute renal failure (ARF) is a frequent complication of coronary artery bypass grafting (CABG) surgery and is strongly associated with perioperative morbidity and mortality. We hypothesized that renal artery stenosis (RAS), causing occult renal ischemia, may be an important factor contributing to development of ARF after CABG surgery. METHODS: Preoperative and intraoperative data on 798 consecutive adult patients undergoing CABG surgery with cardiopulmonary bypass from February 1, 1995 to February 1, 1997 (who had also undergone an abdominal aortogram for the evaluation of RAS) were recorded and entered into a computerized database. The development of ARF was defined as a rise in serum creatinine of 1 mg/dL (88.4 micromol/L) above baseline postoperatively. The association between the presence of renal artery stenosis together with preoperative and intraoperative variables and the development of ARF was assessed by multivariate logistic regression. RESULTS: A total of 798 patients underwent isolated coronary bypass grafting, of which 18.7% demonstrated 50% or more RAS. ARF developed in 82 patients (10.2%), of which three (0.3%) required dialysis support. The mortality for patients who developed ARF was 14% (OR 15, P=0.0001) compared to 0.2% among those who did not develop ARF. The presence of renal artery stenosis of any severity ranging from unilateral 50% RAS to bilateral 95% RAS was not associated with the subsequent development of ARF. CONCLUSIONS: The development of ARF following CABG surgery is associated with high mortality. The presence of RAS does not appear to increase the risk for developing ARF.     

Pulsed Doppler sonography of the hilar renal artery: differentiation of obstructive from nonobstructive hydronephrosis in children

BACKGROUND/PURPOSE: It is difficult to detect the arcuate or cortical renal arteries when performing pulsed Doppler sonography (PDS) for congenital hydronephrosis. This study was undergone to assess the usefulness of PDS of the hilar renal artery to differentiate obstructive from nonobstructive hydronephrosis. METHODS: The authors performed PDS of the hilar renal artery in 80 normal children: 20 aged 0 to 1 months (group I), 20 aged 1 to 12 months (group II), 20 aged 1 to 6 years (group III), and 20 aged 7 to 15 years (group IV). Based on diuretic renography findings, 22 kidneys from 19 children with a ureteropelvic junction (UPJ) stricture were divided into 7 dilated obstructed and 15 dilated nonobstructed kidneys. The peak-systolic velocity (PSV), end-diastolic velocity (EDV), mean average velocity (Vm) and the resistive index (RI = [PSV - EDV]/PSV) were measured at the hilar renal artery. RESULTS: There was a significant difference in the RI of the hilar renal artery between obstructive and nonobstructive hydronephrosis. CONCLUSION: A pulsed Doppler evaluation of the hilar renal artery is useful for detecting an obstructive UPJ stricture compared with assessing arcuate or cortical renal arteries.     

Correlation between renal blood flow and intrarenal Doppler measurements in canine autotransplanted kidney

For proper interpretation of the changes in intrarenal Doppler ultrasound measurements, we evaluated the direct correlation between total renal blood flow and intrarenal Doppler parameters. Under progressive constriction of the renal artery in canine autotransplanted kidneys, we simultaneously measured blood flow at the main renal artery and Doppler parameters at the segmental artery. The changes in total renal blood flow were well correlated to changes in peak systolic velocity, end diastolic velocity and resistive index (RI) of the segmental artery (r = 0.964, 0.960 and 0.486, respectively). The acute reduction of total renal blood flow produces a linear decrease in Doppler parameters at intrarenal arteries. These results should be helpful for better understanding the changes in renal hemodynamics in various pathologic conditions as well as those induced by various vasoactive agents including angiotensin converting enzyme inhibitor. This revised version was published online in September 2006 with corrections to the Cover Date.