Severity Of Renal Artery Stenosis Research Articles

The performance of duplex ultrasonography for the assessment of renal artery stenosis in Takayasu’s arteritis patients

BackgroundThis study intends to analyze the hemodynamic parameters of the renal artery in patients with Takayasu’s arteritis (TAK) to explore the diagnostic efficacy of duplex ultrasonography in assessing the involved renal artery in TAK patients.MethodsOne hundred fifteen TAK patients with 314 renal arteries were retrospectively analyzed, who were admitted to Peking Union Medical College Hospital between 2017 and 2022. These patients underwent both renal artery ultrasonography and angiography within a 4-week period. Specifically, the study compared seven ultrasonic parameters across groups categorized by the severity of renal artery stenosis (RAS), including noninvolvement, < 50% stenosis, 50–69% stenosis, and 70–99% stenosis. Receiver operating characteristic (ROC) curves were employed to determine the optimal threshold values for renal artery peak systolic velocity (RPSV), renal-aortic PSV ratio (RAR), and renal-interlobar PSV ratio (RIR) in order to diagnose various degrees of RAS in TAK patients.ResultsStatistically significant differences were observed in RAR and RIR among the four groups (all P < 0.05). However, no statistically significant differences were found in RPSV and AT between the moderate stenosis group (50–69% stenosis) and the severe stenosis group (70–99% stenosis). The discrimination of interlobar PSV (IPSV) and interlobar RI (IRI) was not significant, and IEDV did not show statistical significance among the four groups.For TAK patients, the recommended thresholds of RPSV for the diagnosis of renal artery involvement (RAI), ≥ 50% RAS, and ≥ 70% RAS were determined to be 143 cm/s, 152 cm/s, and 183 cm/s, respectively. The sensitivities, specificities, and accuracies of these thresholds were all found to be greater than 80%. Additionally, the optimal thresholds of RIR for detecting RAI, ≥ 50% RAS, and ≥ 70% RAS were determined to be 4.6, 5.6, and 6.4, respectively, with satisfactory diagnostic efficiencies. The areas under the curve (AUCs) for RPSV and RIR were calculated to be 0.908 and 0.910, respectively, for the diagnosis of ≥ 50% RAS, and 0.876 and 0.882 for the diagnosis of ≥ 70% RAS. When the aortic PSV is greater than or equal to 140 cm/s, the RAR exhibits inadequate diagnostic efficacy. Conversely, when the aortic PSV is less than 140 cm/s, a RAR value of 2.2 or higher can be employed as the diagnostic threshold for identifying RAS of 70% or greater, with a sensitivity of 84.00%, specificity of 89.93%, and an overall accuracy of 89.08%.ConclusionIn the present study, it has been demonstrated that RPSV and RIR possess substantial diagnostic value as ultrasonic parameters for diagnosing RAS in TAK patients. Furthermore, when assessing the diagnostic efficacy of RAR, it is crucial to consider the severity of aortic stenosis as a determining factor.

Cardiovascular complications according to severity of renal artery stenosis based on Doppler ultrasound

IntroductionThe interactions between atherosclerotic renal artery stenosis, independently of severity, and cardiovascular risk, and mortality, are complex and have not been fully researched. The aim of this study was the assessment of the risk of cardiovascular events and mortality in patients with haemodynamically non-significant (NS-RAS) and significant renal artery stenosis (S-RAS) diagnosed with ultrasonography.Material and methodsThe study group consisted of all consecutive patients (n = 2059) who underwent Doppler ultrasound of the renal arteries during a 4-year period. The patients were divided, according to the renal aortic ratio (RAR), into the following groups: S-RAS (RAR ≥ 3.5), NS-RAS (1 &lt; RAR &lt; 3.5), and normal RAR (control group; RAR ≤ 1). The risk of cardiovascular events and death was estimated using Cox’s proportional hazard model, including severity of RAS, age, and gender, based on the data from the National Health Fund on causes of hospitalization, deaths, and statistics on percutaneous coronary angioplasty procedures.ResultsSignificant renal artery stenosis was found in 112 patients (5.4%), NS-RAS in 313 patients (15.2%), and 1634 patients (79.4%) were qualified to the control group. The NS-RAS group had an increased risk of stroke (7.0% vs. 3.0%, HR = 1.77, p = 0.032); S-RAS patients were at increased risk of heart failure (16.1% vs. 5.2%, HR = 2.19, p = 0.002) and death (19.6% vs. 4.3%, HR = 3.08, p &lt; 0.001).ConclusionsThe presence of haemodynamically non-significant renal artery stenosis is an indicator of systemic atherosclerotic changes in vital organs and an important cardiovascular risk factor for stroke.

Influence of renal artery stenosis morphology on hemodynamics

Objective Currently, the clinical classification of the severity of renal artery stenosis (RAS) solely depends on the degree of stenosis. In addition, when the stenosis degree is between 50% and 70%, the clinical strategy is decided based on whether the RAS is hemodynamically significant. In this study, the influence of RAS morphological parameters on hemodynamics was numerically analyzed to provide a theoretical basis for clinical treatment. Methods Idealized RAS models were established to investigate the hemodynamic effects of the stenosis length, asymmetric stenosis, and direction of the opening of the renal artery. Results The longer the stenosis length, the greater is the ratio of the low time-averaged wall shear stress (WSS) and high oscillatory shear index (OSI) area distal stenosis (when the stenosis area is the same). In addition, asymmetric stenosis leads to a significant increase in the ratio of the renal artery peak systolic velocity (R-PSV) and the abdominal aorta peak systolic velocity (A-PSV) when the stenosis area is 60–70%. Furthermore, the fraction flow reserve (FFR) of the RAS model with 12 mm stenosis length, upward eccentricity and upward direction of renal artery opening was approximately equal to the cumulative value of the influence of different stenosis morphologies on FFR. Conclusion An assessment of the severity of RAS should consider the stenosis area and other morphological parameters, including the length and asymmetry of RAS as well as the direction of the opening of renal artery, particularly when the stenosis degree of RAS is between 50% and 70%.

Renal Artery Stenosis in the Patient with Hypertension: Prevalence, Impact and Management.

Atherosclerosis is the primary cause of renal artery stenosis. Atherosclerotic renal artery stenosis (ARAS) is associated with three clinical problems: renovascular hypertension, ischemic nephropathy and cardiac destabilization syndrome which pose huge healthcare implications. There is a significant rate of natural disease progression with worsening severity of renal artery stenosis when renal revascularization is not pursued in a timely manner. Selective sub-groups of individuals with ARAS have had good outcomes after percutaneous renal artery stenting (PTRAS). For example, individuals that underwent PTRAS and had improved renal function were reported to have a 45% survival advantage compared to those without improvement in their renal function. Advances in the imaging tools have allowed for better anatomic and physiologic measurements of ARAS. Measuring translesional hemodynamic gradients has allowed for accurate assessment of ARAS severity. Renal revascularization with PTRAS provides a survival advantage in individuals with significant hemodynamic renal artery stenosis lesions. It is important that we screen, diagnosis, intervene with invasive and medical treatments appropriately in these high-risk patients.

Noninvasive and Patient-Specific Assessment of True Severity of Renal Artery Stenosis for New Guidelines for Planning Stent Therapy

Noninvasive and Patient-Specific Assessment of True Severity of Renal Artery Stenosis for New Guidelines for Planning Stent Therapy

The renal artery is involved in Chinese Takayasu’s arteritis patients

Takayasu's arteritis is a rare systemic vasculitis mainly affecting the aorta and its major branches. Previous studies have suggested that almost half of the Asian Takayasu's patients have renal artery involvement. However, due to the rarity of the disease, little is known about renal artery involvement in Chinese Takayasu's arteritis patients. Here, we retrospectively reviewed and analyzed 411 patients diagnosed with Takayasu's arteritis in our center to explore the clinical features of renal artery involvement in this group of patients. Of these, 201 patients were diagnosed to have renal artery involvement, with stenosis (78.1%) the most common renal artery pattern. Compared to those without, patients with renal artery involvement were significantly younger at disease onset (23.5 vs 25.6 years) and more frequently had hypertension (74.6% vs 28.1%). Congestive heart failure (22.4% vs 7.6%) and pulmonary hypertension (19.9% vs 9.5%) were both significantly more prevalent among patients with than those without renal artery involvement. The estimated glomerular filtration rate (eGFR) significantly decreased as the severity of renal artery stenosis increased. Age at disease onset older than 24 years (odds ratio 6.06 [95% Confidence Interval 2.76-13.3]), disease duration longer than 19 months (3.35 [1.52-7.4]) and renal artery involvement (8.7 [3.8-20.1]) were independent risk factors for renal dysfunction (eGFR under 90 mL/min/1.73m2) among patients with Takayasu's arteritis. Thus, patients with renal artery involvement have more severe cardiac and renal dysfunction compared to those without. The eGFR is correlated negatively with the severity of renal artery stenosis.

Secondary hypertension: Renovascular hypertension

Takayasu’s arteritis is a rare systemic vasculitis mainly affecting the aorta and its major branches. Previous studies have suggested that almost half of the Asian Takayasu’s patients have renal artery involvement. However, due to the rarity of the disease, little is known about renal artery involvement in Chinese Takayasu’s arteritis patients. Here, we retrospectively reviewed and analyzed 411 patients diagnosed with Takayasu’s arteritis in our center to explore the clinical features of renal artery involvement in this group of patients. Of these, 201 patients were diagnosed to have renal artery involvement, with stenosis (78.1%) the most common renal artery pattern. Compared to those without, patients with renal artery involvement were significantly younger at disease onset (23.5 vs 25.6 years) and more frequently had hypertension (74.6% vs 28.1%). Congestive heart failure (22.4% vs 7.6%) and pulmonary hypertension (19.9% vs 9.5%) were both significantly more prevalent among patients with than those without renal artery involvement. The estimated glomerular filtration rate (eGFR) significantly decreased as the severity of renal artery stenosis increased. Age at disease onset older than 24 years (odds ratio 6.06 [95% Confidence Interval 2.76-13.3]), disease duration longer than 19 months (3.35 [1.52-7.4]) and renal artery involvement (8.7 [3.8-20.1]) were independent risk factors for renal dysfunction (eGFR under 90 mL/min/1.73m2) among patients with Takayasu’s arteritis. Thus, patients with renal artery involvement have more severe cardiac and renal dysfunction compared to those without. The eGFR is correlated negatively with the severity of renal artery stenosis.

Comparing Diagnostic Techniques of Magnetic Resonance Angiography (MRA) and Doppler Ultrasonography in Determining Severity of Renal Artery Stenosis.

Renal artery stenosis is one of the important causes of hypertension and end stage renal failure. Magnetic resonance angiography (MRA) and Doppler ultrasonography are non-invasive and safe diagnostic techniques that have also high sensitivity and specificity. Since the accuracy and reliability of these techniques depend upon technicians and softwares, we decided to evaluate and compare the sensitivity and specificity of these techniques in Isfahan. Our study included all the patients (37 patients) who underwent renal artery angiography during 2 years from May 2003 to May 2005 and up to six months after that had underwent MRA (21 patients) and Doppler sonography (16 patients) in Isfahan. Renal artery angiography was considered as the gold standard. Sensitivity, specificity, positive and negative predictive values of 100%, 25%, 25%, and 100% were obtained for MRA respectively. Specificity and positive predictive values (PPV) of Doppler sonography were 67%. Its sensitivity and negative predictive values (NPV) were 57%. Although it seems that technician dependency, technical and software problems were the reasons of low specificity of gadolinium-enhanced MRA in our study, further studies with larger sample sizes are recommended.

Revascularization versus medical therapy for renal-artery stenosis. The ASTRAL Investigators. The New England Journal of Medicine 2009; 361: 1953—1962

Study objective: The objective of ASTRAL was to determine whether percutaneous revascularization combined with medical therapy compared to medical therapy alone improves renal function and other outcomes, such as blood pressure, time to first renal event, time to first major cardiovascular event, and mortality. Study population: ASTRAL enrolled 806 patients with atherosclerotic renovascular disease from 57 centers. Patients were screened if treating clinicians felt they had clinical features suggestive of underlying atherosclerotic renovascular disease (i.e. hypertension refractory to medical therapy, or renal impairment as suggested by laboratory measurements). All patients had to have an imaging modality (i.e. computed tomographic angiography (CTA), magnetic resonance angiography (MRA) or renal artery ultrasound). This imaging had to convey that the patient had ‘substantial’ anatomical atherosclerotic stenosis in at least one renal artery that was suitable for endovascular therapy. Also, the treating clinician had to be ‘uncertain’ that the patient would benefit from revascularization. Fifty-nine percent of patients were reported to have renal artery stenosis of &gt; 70%, and 60% had a serum creatinine of ≥ 150 mmol per liter. Design and methods: ASTRAL was a randomized, unblinded study of patients with atherosclerotic renal artery disease who were assigned to percutaneous revascularization plus best medical therapy or best medical therapy alone. The primary outcome of the ASTRAL trial was the change of renal function over time, as determined by the mean slope of the reciprocal of serum creatinine. Secondary outcomes included blood pressure, time to first renal event (defined as: new onset of kidney injury, dialysis, renal transplantation, nephrectomy, or death from renal failure), time to first major cardiovascular event (defined as: myocardial infarction, stroke, death from cardiovascular cause, hospitalization for angina, fluid overload or congestive heart failure, coronary artery revascularization, or another peripheral arterial procedure), and all-cause mortality. Randomization was 1:1 via computer algorithm and was stratified by serum creatinine, glomerular filtration rate (GFR), severity of renal artery stenosis, kidney length on ultrasound, and rate of progression of renal impairment. Patients who were assigned to the revascularization plus medical therapy arm underwent percutaneous revascularization within 4 weeks. The procedure type (angioplasty alone or with stenting), was left to the discretion of the local operator. Distal protection devices were not used. Medical therapy in both arms consisted of antihypertensive drugs, statins, and antiplatelet agents. The trial was powered to detect a 20% reduction in the mean slope of the reciprocal of serum creatinine. Based on low crossover rates, it was determined that at least 750 patients would have to be enrolled. Analysis was by intention to treat. Continuous variables were subject to repeated measures analysis. Time-to-event data were expressed via Kaplan Meier curves and compared via log-rank testing. Prespecified subgroup analyses included baseline serum creatinine, GFR, severity of renal artery stenosis, kidney length, and progression of renal disease. Results: Of the 806 patients included, 403 were randomized to the revascularization arm and 403 to medical therapy only. The median follow-up was 34 months. Only 337 (83%) patients randomized to revascularization underwent the procedure, whereas 24 patients (6%) randomized to the medical therapy arm underwent revascularization. The number of antihypertensive medications used was greater in the medical therapy group than in the revascularization group at the 12-month follow-up: 2.97 versus 2.77 ( p = 0.03). The mean slope of the reciprocal of the serum creatinine concentration was —0.07 × 10— 3 liters per micromole per year in the revascularization group versus —0.13 × 10—3 liters per micromole per year in the medical-therapy group (difference of 0.06 × 10 —3 liters per micromole per year) (95% confidence interval [CI], —0.002 to 0.13, p = 0.06) with a trend favoring revascularization. After 5 years of follow-up, there was a trend toward lower mean systolic blood pressure (1.6 mmHg lower, p = 0.06) in the revascularization group. However, the mean diastolic blood pressure was significantly lower in the medical therapy group at long-term follow-up (divergence of slope of mean diastolic blood pressure: 0.61 mmHg per year, p = 0.03). There was no significant difference between renal events, time to first renal event, acute kidney injury, or development of end-stage renal disease in either group. Further, there was no difference in major cardiovascular events or overall survival in either group. The periprocedural complication rate within the revascularization group was 9% (31/359 patients). Fifty-five out of 280 patients (20%) had an adverse event by 1 month post procedure. Overall, there were 31 serious complications of revascularization in 23 patients. Per protocol analysis of patients suggested that there was no significant difference in outcomes between patients who received revascularization versus medical therapy. No differences between treatment groups were identified in any of the pre-specified subgroup analyses. Conclusions: Renal artery stenting combined with medical therapy did not improve renal function compared to medical therapy alone in patients with atherosclerotic renal artery disease.

Assessment of Renal Artery Stenosis Severity by Pressure Gradient Measurements

Assessment of Renal Artery Stenosis Severity by Pressure Gradient Measurements

Left Ventricular Hypertrophy in Patients with Renal Artery Stenosis

Left ventricular hypertrophy (LVH) has been shown to be 3 times more prevalent in patients with renal artery stenosis (RAS) compared to essential hypertension, but factors that predict LVH in this population are not known. We identified 66 patients with unilateral renal artery stenosis and an interpretable electrocardiogram (ECG). LVH by either Cornell voltage-duration product or Sokolow-Lyon voltage criteria was present in 18 of the 66 patients (27%). The mean intra-aortic blood pressure was 100 +/- 14 mm Hg in patients with LVH, and 104 +/- 23 mm Hg in those without LVH (P = 0.37). The average stenosis by quantitative computerized angiography was 68 +/- 17% in patients with LVH, and 64 +/- 13% in those without LVH (P = 0.34). The mean translesional pressure gradient was 11 +/- 15 mm Hg in patients with LVH, and 13 +/- 20 mm Hg in those without LVH (P = 0.60). Using linear regression models, there was no correlation between intra-aortic blood pressure, percentage of stenosis, or translesional pressure gradient and either Cornell voltage-duration product or Sokolow-Lyon voltage criteria. In summary, LVH using ECG criteria was present in 27% of patients with unilateral RAS but was not associated with blood pressure at the time of the procedure or severity of renal artery stenosis.

The profile of cardiac patients with renal artery stenosis

ObjectivesWe examined the prevalence and severity of renal artery stenosis (RAS) in patients undergoing cardiac catheterization who were deemed at risk for RAS based on clinical or laboratory criteria for study entry, but who had not previously been suspected of having RAS. BackgroundThe diagnosis of atherosclerotic RAS remains problematic because its clinical manifestations are nonspecific. MethodsConsecutive patients undergoing non-emergent cardiac catheterization at a single institution during a 12-month period were evaluated using standardized clinical, laboratory, and angiographic criteria. Patients exhibiting at least one of four predefined selection criteria (severe hypertension, unexplained renal dysfunction, acute pulmonary edema with hypertension, or severe atherosclerosis) were prospectively registered and underwent coincident diagnostic renal angiography. ResultsRenal angiography was performed in 851 patients and was diagnostic in 837. Angiographically evident renal atherosclerosis was present in 39% of the population, with RAS ≥50% in 120 (14.3%) and severe stenosis (≥70%) in 61 (7.3%). Severe stenosis was present in 48 (7%) patients with severe atherosclerosis, 38 (16%) with renal dysfunction, 25 (9%) with hypertension, and 2 (22%) with acute pulmonary edema with hypertension. The prevalence was higher in those exhibiting multiple selection criteria. In a multivariate model, severe RAS was associated with age, female gender, reduced creatinine clearance, increased systolic blood pressure, and peripheral or carotid artery disease. ConclusionsIn a population at risk of, but not previously suspected of having RAS, severe RAS is associated with simple and readily determined clinical and laboratory patient characteristics. These data facilitate focused application of diagnostic renal angiography.

The right diagnostic work-up: investigating renal and renovascular disorders.

Renovascular disease is present in about 10-40% of patients with end-stage renal disease, and constitutes the fastest-growing group of end-stage renal disease patients. The unselective correction of renal artery stenosis has led to disappointing results. Most studies that have compared conservative treatment with angioplasty have found only modest or no beneficial effects of angioplasty on renal function and blood pressure. It is therefore mandatory to evaluate the functional significance of a stenosis before intervention. Patients most likely to respond favourably to revascularization should be identified. Factors that affect outcome include the severity of renal artery stenosis, type of treatment of renal artery stenosis and, most importantly, underlying renal disease, which prevents a favourable response even after successful correction of renal artery stenosis. Doppler ultrasonography to evaluate the renal resistance index [1 - (end diastolic velocity/maximum systolic velocity) x 100] or captopril scintigraphy are the best methods by which to classify patients as responders or non-responders to intervention. In patients with a renal resistance index > or = 80%, improvement of renal function or blood pressure is highly unlikely, despite successful correction of renal artery stenosis. The value of the renal resistance index can also be extended to patients with non-stenotic renal diseases. Identifying patients at risk for irreversible loss of renal function and who may benefit from intervention is a high research priority.

Pulse transmission coefficient in the evaluation of the severity of renal artery stenosis

Pulse transmission coefficient in the evaluation of the severity of renal artery stenosis

Techniques for predicting a favourable response to renal angioplasty in patients with renovascular disease.

Renovascular disease is present in some 10-40% of patients with end-stage renal disease, and constitutes the fastest-growing group of end-stage renal disease patients. The unselective correction of renal artery stenosis has led to disappointing results. Most studies that compared conservative treatment with angioplasty found only modest or no beneficial effects of angioplasty on renal function and blood pressure. It is therefore mandatory to evaluate the functional significance of a stenosis before intervention. Patients with a high likelihood of a favourable response should be identified. Factors that affect outcome include the severity of renal artery stenosis, the procedure used to treat renal artery stenosis (antihypertensive drugs, angioplasty with or without stenting, or surgery), radiocontrast nephrotoxicity, atheroembolism and, most importantly, underlying renal disease, forestalling a favourable response of renal function or blood pressure even after the successful correction of renal artery stenosis. Evaluation of the renal resistance index using Doppler ultrasound or captopril scintigraphy are the best methods by which to classify patients as responders or non-responders to intervention. Each factor has to be considered before the correction of renal artery stenosis to achieve satisfactory results with regard to an improvement in renal function and blood pressure.

Progression of renal artery stenosis in patients undergoing cardiac catheterization

Background Renal artery stenosis is potentially correctable by either revascularization surgery or percutaneous methods. However, appropriate use of these techniques has been hampered by a lack of data on the natural history of this disease. This study assesses the prevalence, risk factors for progression, and effect on renal function of angiographically demonstrated renal artery disease in patients undergoing cardiac catheterization. Methods The severity of renal artery stenosis was quantified in all patients who underwent abdominal aortography as part of a diagnostic cardiac catheterization study at Duke University Medical Center between January 1989 and February 1996. Results There were 14,152 patients in the study (mean age 61 ± 12 years, 62% male). Normal renal arteries were identified in 12,543 (88.7%) patients, insignificant disease (<50% stenosis) in 1 or more vessels in 726 patients (5.1%), and significant stenosis in 883 patients (6.3%). Significant bilateral renal artery stenosis was present in 178 patients (1.3%). By multivariate logistic regression, elevated serum creatinine level, coronary artery disease, peripheral vascular disease, hypertension, cerebrovascular disease, older age, female sex, and family history of coronary artery disease were identified as independent predictors of significant renal arterial disease. Disease progression was assessed in 1189 patients. Mean time between cardiac catheterizations was 2.6 ± 1.6 years. Significant disease progression occurred in 133 patients (11.1%). Independent predictors of disease progression were female sex, age, coronary artery disease at baseline, and time between baseline and follow-up. At follow-up, serum creatinine level was significantly higher in patients who demonstrated ≥75% stenosis in 1 or more vessels (mean creatinine level 141 ± 114 μmol/L compared with those with insignificant disease (mean creatinine level 97 ± 44 μmol/L ( P = .01). Conclusions Renal artery disease is frequently progressive in patients who undergo cardiac catheterization for investigation of coronary artery disease. Significant stenotic disease may develop over a short period despite evidence of normal renal arteries at prior catheterization. (Am Heart J 1998;136:913-8.)

Renal Artery Evaluation: Comparison of Spiral CT Angiography to Intra-arterial DSA

To assess the role of spiral computed tomographic angiography (CTA) in renal artery evaluation. The authors prospectively performed both CTA and intraarterial digital subtraction angiography (IA-DSA) in 50 consecutive patients (24 males and 26 females) who ranged between 9 and 77 years old (mean, 39.3 years), in whom renovascular hypertension was suspected (n = 32) or who were potential renal donors (n = 18). The major scan parameters of CTA were 3-mm collimation, 4-5-mm/sec table speed, and 2-mm reconstruction interval. Both CTA and IA-DSA images were blindly interpreted by two radiologists with respect to the number of accessory renal arteries and the location and severity of renal artery stenosis. CTA demonstrated 27 of 28 accessory renal arteries (detection rate = 96%). For the detection of stenoses greater than 50% (37 of 127 renal arteries, at 40 sites), the sensitivity and specificity of CTA were 90% and 97%, respectively. For the detection of stenoses greater than 50% in the main renal arteries (32 of 99 main renal arteries, at 32 sites), the sensitivity and specificity of CTA were 100% and 97%, respectively. CTA is a reliable and accurate screening modality for the evaluation of renal arteries in patients with suspected renovascular hypertension and in potential renal donors.

Standard dose Gd-DTPA dynamic MR of renal arteries.

Renal MR contrast enhancement depends on the timing of image acquisition. Limited human trials have demonstrated efficacy of renal artery stents on salvage of renal function. This study assessed the ability of dynamic gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) administration to demonstrate renal artery stenosis and renal stent patency compared to conventional angiography as the gold standard. Twenty subjects referred for renal angiography underwent 22 dynamic MR studies, including 7 with renal artery stenting (Palmaz P204 or P201, Johnson & Johnson, Sydney, Australia). All were examined with conventional angiography and after dynamic Gd-DTPA infusion. Coronal MR images of the kidneys were acquired using a GE Signa 1.5-T magnet (General Electric Medical Systems, Milwaukee, WI) (fast spoiled gradient echo [FSPGR]; TE=4.2 msec, TR=68-150 msec, flip angle=75 degrees) 0 to 600 seconds after iv bolus injection of 15 ml of Gd-DTPA during sequential breath-hold acquisitions, 13 to 32 seconds each. All 51 renal arteries (13 stenosed, 38 normal) were detected with dynamic MRI. Severity of renal artery stenosis was classified correctly with an accuracy of 98% (95% confidence interval [CI]: 85-100), yielding 98% specificity and 100% sensitivity. All nine renal stents were visualized with 100% accurate patency documentation. FSPGR MRI with bolus Gd-DTPA administration can provide adequate time and spatial resolution to demonstrate renal artery stenosis.

Increased platelet volume and platelet mass in patients with atherosclerotic renal artery stenosis.

1. Platelet volume was measured in citrated blood in two groups of patients at risk of having atherosclerotic renal artery stenosis, namely (i) 30 patients with severe hypertension, and (ii) 44 patients with peripheral vascular disease. 2. Platelet volume was increased in patients with hypertension who had atherosclerotic renal artery stenosis diagnosed by angiography: no renal artery stenosis, median 7.2 (interquartile range 0.5) x 10(-15)/l; renal artery stenosis 7.8 (0.8) x 10(-15)/l; platelet mass also increased with increasing severity of renal artery stenosis. Platelet volume correlated with severity of renal artery stenosis (rs = 0.391, 2p = 0.033, n = 30). Similarly, platelet volume correlated with severity of renal artery stenosis in patients with peripheral vascular disease (rs = 0.319, 2p = 0.035, n = 44). Serum immunoreactive platelet-derived growth factor (predominantly released from platelets) and plasma immunoreactive interleukin-6 (a cytokine which has been postulated to regulate platelet volume) concentrations were not different between hypertensive patients with and without renal artery stenosis. 3. Since large platelets are hyperactive, increased platelet volume may contribute to the development of atherosclerotic renal artery stenosis. However, the present data do not lend support to the hypothesis that platelet-derived growth factor is central to renal artery atherogenesis. Interleukin-6 does not appear to regulate platelet volume.

Doppler evaluation of renal artery stenosis: interobserver agreement in the interpretation of waveform morphology.

Analysis of Doppler waveform morphology for features of the tardus-parvus phenomenon has been promoted as a useful and accurate means for detecting renal artery stenosis. The purpose of this study was to examine and quantify the interobserver agreement of such an analysis and to determine if interobserver differences limit the value of this approach for predicting renal artery stenosis. Four observers independently categorized renal artery waveforms of 47 patients (94 kidneys) clinically selected for renovascular hypertension. Waveforms were classified into five categories based on the presence and severity of tardus-parvus changes in the systolic upstroke and early systolic peak. This categorization was then compared with angiographic findings, and the results were analyzed with receiver-operating-characteristic curves. Kappa statistics and agreement tables were computed to evaluate interobserver agreement. Interobserver agreement in the waveform analysis for the four interpreters was statistically significant (p < 0.001). The receiver-operating-characteristic areas produced by the observers indicated, however, that such waveform classification was not strongly predictive of renal artery stenosis. We conclude that substantial agreement in the interpretation of waveform morphology can be obtained between independent observers, and that such differences that do exist do not preclude the use of the pattern-recognition approach to waveform analysis. Even so, the specific application of this strategy to the waveform contours of early systole was not successful in predicting the presence or severity of renal artery stenosis.