Renal artery stent placement in renal artery stenosis: technical and early clinical results

Percutaneous Endovascular Therapy of Renal Artery Stenosis: Technical and Clinical Developments in the past Decade

Renal artery stenosis may initiate or exacerbate arterial hypertension and/or renal insufficiency. During the last decade, technical improvements of diagnostic and interventional endovascular tools have led to more widespread use of endoluminal renal artery revascularization and broader indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Grüntzig in 1978, numerous single-center studies have documented the benefits of percutaneous renal revascularization. In the early 1990s, stent implantation was added to the interventionist's armamentarium for treating renal artery stenosis due to atherosclerosis or fibromuscular dysplasia. The metaanalysis of 3 randomized studies comparing balloon angioplasty with best medical therapy found intervention to be beneficial for blood pressure control but not for preservation of renal function. Despite the absence of randomized studies, there is mounting evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has a positive impact on blood pressure control and renal function. This article summarizes the technical improvements in these endovascular tools during the last decade and gives an overview concerning their clinical impact on renal artery revascularization.

Technological Advances in the Design of Catheters and Devices Used in Renal Artery Interventions: Impact on Complications

Purpose:

To analyze the impact of technical improvements in stent devices and guiding catheters (e.g., reduced device diameter, increased flexibility) on the complication rates associated with percutaneous renal artery interventions.

Methods:

During a 5-year period (1997–2001), 268 consecutive patients (178 men; mean age 67±9 years) had 370 atherosclerotic renal artery stenoses (RAS) ≥70% treated with angioplasty/stenting in 320 procedures. The guiding catheter technique was used routinely until 2000; in 2001, a guiding sheath was used in 29% of cases. From 1997 to 2000, sealing devices were frequently used for sheath removal; during the last year, the sheaths were removed using the Femostop device.

Results:

In 320 interventions, 32 (10%) complications occurred, with a decreasing frequency during the last 2 years (1996/97: 13% [7/53]; 1998: 16% [9/57]; 1999: 15% [11/74]; 2000: 4% [3/70]; 2001: 3% [2/66]). There were 21 (6.6%) local complications, including 4 cases requiring permanent hemodialysis after the intervention and 11 (3.4%) access site complications. No procedure-related death occurred. During the study period, the average sheath diameter was reduced from 8.15±0.76 F to 6.15±0.63 F (p<0.05). Mean procedural time was reduced from 42±13 minutes to 23±11 minutes (p<0.05). The initial heparin dose was reduced from 10,000 to 5000 units.

Conclusions:

In parallel with the use of more flexible catheters and premounted stents of lower profile, the complication rate of renal angioplasty/stenting of atherosclerotic RAS has been reduced significantly during a 5-year period.

Technical discussion of diagnostic angiography and intervention of atherosclerotic renal artery stenosis

Renal artery stenting remains an important adjuvant treatment for true-resistant hypertension, although recent disappointing randomized trials highlight the importance of careful patient selection. Safe and successful renal interventions begin with critical core knowledge regarding renal artery anatomy and understanding the often hostile nature of the parent vessel (pararenal aorta). Armed with fundamental knowledge about anatomy and renal ostial disease pathology, it becomes easier to understand the advantages of less traumatic access techniques and how low-profile contemporary flexible stents have enhanced outcomes. In addition to suggested techniques based on detailed understanding of the vessel architecture and pathology, we will review the current available US Food and Drug Administration-approved balloon-expandable on-label renal stents and discuss the role of intravascular ultrasound for definition of lesion severity, stent sizing, and stent apposition. The durability of renal stenting will also be discussed, as will the velocity criteria for duplex surveillance. Lastly, the current empirical data related to renal embolic protection is provided, along with insight into technical issues in this domain.

Renal artery stenosis: prevalence of, risk factors for, and management of in-stent stenosis

Atherosclerotic renal artery stenosis is common and is associated with hypertension and chronic kidney disease. More frequent use of percutaneous renal artery stent placement for the treatment of renal artery stenosis during the past 2 decades has increased the number of patients with implanted stents. In-stent stenosis is a serious problem, occurring more frequently than earlier reports suggest and potentially resulting in late complications. Currently, there are no guidelines covering the approach to restenosis after renal artery stent placement. This article reviews data on the prevalence of and risk factors for the development of in-stent stenosis and the clinical manifestations, evaluation, and treatment of in-stent stenosis and suggests a strategy for the management of patients after percutaneous renal artery stent placement.

Endovascular intervention for renal artery stenosis

Renovascular diseases are common conditions with important implications on cardiovascular morbidity and mortality. Renal artery stenosis (RAS) is present in 1-5% of patients with hypertension (HTN) in the US with the vast majority of caused by atherosclerosis. Atherosclerotic RAS is related not only to uncontrolled HTN, but also to renal dysfunction. Atherosclerotic RAS in the USA has been reported to account for approximately 14-16% of new patients requiring dialysis each year. Hence a concerted effort was made in the last decade to treat renovascular stenosis using newly developed endovascular therapies to improve cardiovascular morbidity and renal function. A review on new advances in the endovascular management of renal artery stenosis with low profile stents, embolic protection devices, and drug eluting stents is presented.

Clinical efficacy of percutaneous renal revascularization with stent placement in hypertension among patients with atherosclerotic renovascular diseases

AIM

The aim was to assess the effect of renal angioplasty with stent on systolic, diastolic, and mean arterial blood pressure (MAP) in awake and sleep time with ambulatory blood pressure (ABP) monitoring (Holter monitoring).

MATERIALS AND METHODS

Patients with angiographically proven atherosclerotic renal artery stenosis (RAS) were referred to the Angiography Department of Imam Hospital for intervention during a 1-year period from June 2008 to December 2009. Primary stent placement was attempted by a single operator in 27 severe RAS cases although 1 case was omitted from the study because of technical failure. Pre- and postprocedure creatinine levels, ejection fraction (EF), history of diabetes mellitus (DM), and ABP were obtained. Twenty-six (17 men, 9 women; average age, 62.6 years; age range, 90-21 years) consecutive patients participated in the study.

RESULTS

All patients had severe hypertension resistant to multiple medications; 10 patients had impaired renal function (serum creatinine level greater than 130 µmol/L). A total of 3 (11.5%) patients had congestive heart failure, and 10 (37.7%) were diabetic. Hypertension was cured in 1 (4%) patient, had improved in 23 (88.4%) patients, and had failed to respond to treatment in 2 (7.6%). Serum creatinine decreased significantly from 1.46 ± 0.89 to 1.35 ± 0.61 mg/dL (P<0.05).

CONCLUSION

Percutaneous transluminal angioplasty for atheromatous RAS rarely cures hypertension, but improved blood pressure control is often achieved.

One year clinical outcomes of renal artery stenting: the results of ODORI Registry

The safety, efficacy and long term clinical benefits of renal artery revascularization by stenting are still a matter of debate. The aim of our study was to define the safety and efficacy of renal artery stenting with the Tsunami peripheral stent (Terumo Corporation, Tokyo, Japan). The ODORI was a prospective, multicentre registry which enrolled 251 consecutive patients, (276 renal arteries) in 36 centres across Europe. The primary endpoint was acute procedural success defined as <30% residual stenosis after stent placement. Secondary endpoints included major adverse events, blood pressure control, serum creatinine level, and target lesion revascularization (TLR) at 6 and 12 months. Patients were 70 +/- 10 years old, 59% were male, 33% had diabetes, and 96% hypertension. The main indications for renal stent implantation were hypertension in 83% and renal salvage in 39%. Direct stent implantation was performed in 76% of the cases. Acute success rate was 100% with residual stenosis of 2.5 +/- 5.4%. Systolic/diastolic blood pressure decreased from a mean of 171/89 at baseline to 142/78 mmHg at 6 months (p < 0.0001 vs. baseline), and 141/80 mmHg at 12 months (p < 0.0001 vs. baseline). Mean serum creatinine concentration did not change significantly in the total population. However, there was significant improvement in the highest tercile (from 283 micromol/l at baseline to 205 and 209 micromol/l at 6 and 12 months respectively). At 12-months, rates of restenosis and TLR were 6.6 and 0.8% respectively. The 12 month cumulative rate of all major clinical adverse events was 6.4% while the rate of device or procedure related events was 2.4%. In hypertensive patients with atherosclerotic renal artery stenosis Tsunami peripheral balloon-expandable stent provides a safe revascularization strategy, with a potential beneficial impact on hypertension control and renal function in the highest risk patients.

Renal parenchymal preservation after percutaneous renal angioplasty and stenting

BACKGROUND

The intent of endovascular therapy for symptomatic atherosclerotic renal artery stenosis (ARAS) is to preserve parenchyma and avoid renal-related morbidity. The aim of this study is to examine the impact of renal artery intervention on parenchymal preservation.

METHODS

We performed a retrospective analysis of records from patients who underwent endovascular intervention for ARAS and were followed by duplex ultrasound between 1990 and 2008. Renal volume (in cm(3)) was estimated in all patients as renal length (cm) x renal width (cm) x renal depth (cm) x 0.5. The normal renal volume was calculated as 2 x body weight (kg) in cm(3). Failure of preservation was considered to be a persistent 10% decrease in volume. Clinical benefit defined as freedom from renal-related morbidity (increase in persistent creatinine >20% of baseline, progression to hemodialysis, death from renal-related causes) was calculated.

RESULTS

Five hundred ninety-two renal artery interventions were performed. One hundred eighty-six kidneys suffered parenchymal loss (>5%) with an actuarial parenchymal loss rate of 29% +/- 1% at five years respectively. There were no significant differences in age, gender, starting renal volume, or kidney size. However, patients with parenchymal loss had lower eGFR (45 +/- 24 vs 53 +/- 24 mL/min/1.73 m(2); Loss vs noLoss, P = .0002, Mean +/- SD) higher resistive index (0.75 +/- 0.9 vs 0.73 +/- 0.10; P = .0001) and worse nephrosclerosis grade (1.43 +/- 0.55 vs 1.30 +/- 0.49; P = .006) then those not suffering parenchymal loss. Parenchymal loss was associated with significantly worse five-year survival (26% +/- 4% vs 48% +/- 2%; Loss vs noLoss; P < .001) and freedom from renal-related morbidity (70% +/- 5% vs 82% +/- 2%; P < .05) with increased numbers progressing to dialysis (17% vs 7%; P < .006).

CONCLUSION

While parenchymal preservation occurs in most patients, parenchymal loss occurs in 31% of patients and is associated with markers of impaired parenchymal perfusion (resistive index and nephrosclerosis grade) at the time of intervention. Pre-existing renal size or volumes were not predictive of parenchymal loss. Parenchymal loss is associated with a significant decrease in survival and a marked increased renal related morbidity and progression to hemodialysis.

Management of atherosclerotic renovascular disease: the effect of renal artery stenting on renal function and blood pressure

In the last few years, renal artery stenting has gradually evolved into one of the most important therapeutic modalities in the management of atherosclerotic renovascular disease. Stenting is nowadays preferred by a steadily increasing number of physicians, not only because of its significant contribution to blood pressure control, but also because of its documented ability to maintain, and even improve, renal function. At the same time, procedure-related morbidity and mortality rates are extremely low, while recurrent stenosis rates have been repeatedly reported to be minimal. Percutaneous transluminal renal angioplasty (PTRA) and stenting are nowadays considered by many physicians to be the treatment of choice for atherosclerotic renovascular disease.

Treatment of instent restenosis following stent-supported renal artery angioplasty

OBJECTIVES

We prospectively studied the long-term outcome of endovascular treatment of instent renal artery stenosis (IRAS).

BACKGROUND

Restenosis is a considerable drawback of stent-supported angioplasty of renal artery stenosis especially in small vessel diameters. The appropriate treatment strategy is not yet defined.

PATIENTS AND METHODS

During a 10-year period 56 consecutive patients (65 lesions) with their first IRAS were included in a prospective follow-up program (mean follow-up 53 +/- 25 months, range 6-102). Primary endpoint of the study was the reoccurence of IRAS (>or= 70%) after primarily successful treatment of the first IRAS determined by duplex ultrasound.

RESULTS

Primary success rate was 100%, no major complication occurred. Nineteen lesions were treated with plain balloon angioplasty (group 1, 30%), 42 lesions with stent-in-stent placement (group 2, 65%) using various bare metal balloon expandable stents, and 4 lesions with drug-eluting stent angioplasty (group 3, 6%). During follow-up, overall 21 lesions (32%) developed reoccurence of IRAS: n = 7/19 in group 1 (37%), n = 14/42 in group 2 (33%), and n = 0/4 in group 3 (0%; P = 0.573). Reoccurence of IRAS was more likely to occur in smaller vessel diameters than in larger ones [3-4mm: 4/7 (57%); 5 mm: 11/26 (42%); 6 mm: 5/25 (20%); 7 mm: 1/7 (14%), P = 0.088]. Multivariable analysis found bilateral IRAS and IRAS of both renal arteries of the same side in case of multiple ipsilateral renal arteries as independent predictors for reoccurence of IRAS.

CONCLUSION

Treatment of IRAS is feasible and safe. The data demonstrate a nonsignificant trend towards lower restenosis with restenting of IRAS versus balloon angioplasty of IRAS. Individual factors influence the likelihood of reoccurence of IRAS.

Treatment of reoccurring instent restenosis following reintervention after stent-supported renal artery angioplasty

BACKGROUND

Reoccurrence of restenosis following angioplasty of renal instent restenosis is a considerable drawback of stent-supported angioplasty of renal artery stenosis especially in small vessel diameters. We therefore prospectively studied the long-term outcome of different techniques of endovascular treatment of reoccurrence of instent renal artery restenosis after primarily successful reangioplasty focusing on the impact of covered and drug eluting stents, respectively.

PATIENTS AND METHODS

The study included 31 consecutive patients (33 lesions) presenting with their at least second instent restenosis following renal artery stenting who were included in a prospective follow-up program (mean follow-up 36+/-25 months, range 1-85). Primary endpoint of the study was the reoccurrence rate of instent stenosis after primarily successful treatment of instent restenosis determined by duplex ultrasound.

RESULTS

Primary success rate was 100%, no major complication occurred. Seven lesions were treated with balloon angioplasty (21%, group 1), 7 lesions with stent-in-stent placement (21%, group 2), 6 lesions with placement of a covered stent (18%, group 3), 3 lesions with a cutting balloon (9%, group 4), and 10 lesions with placement of a drug eluting stent (31%, group 5). During follow-up, overall 12 lesions (36%) developed reoccurrence of instent restenosis: n=5 in group 1 (reoccurrence rate 71%), n=3 in group 2 (43%), n=1 in group3 (17%), 3 in group 4 (100%), and n=0 in group 5 (0%). Treatment with a cutting balloon was the only significant predictor of restenosis (hazard ratio 32.3 (95% CI, 3.3-315.0); P<0.001).

CONCLUSION

Treatment of at least second renal artery instent restenosis is feasible and safe. Balloon angioplasty and the implantation of a bare metal stent, a covered stent, or a drug eluting stent seemed to offer favorable long-term patency, whereas cutting balloon angioplasty resulted in a very high rate of restenoses and should therefore be discouraged for this indication.

Factors Influencing the Need for Target Vessel Revascularization After Renal Artery Stenting

PURPOSE

To provide additional insight into factors that may be associated with the need for target vessel revascularization (TVR) following de novo renal artery stenting during long-term follow-up.

METHODS

A retrospective chart and database review was conducted to analyze the progress of all patients with de novo symptomatic renal artery stenosis who underwent stent-supported angioplasty under the auspices of the Single Operator, Single Center, Renal Stent Retrospective Study (SOCRATES). The records review identified 782 patients who were enrolled in the study between 1993 and 2004; after excluding 34 (4.5%) patients (lost to follow-up or inadequate data), 748 consecutive patients (412 women; mean age 70.7+/-9.7 years, range 37-92) were suitable for longitudinal analysis. The need for TVR was based on strict clinical criteria (> or =20% rise in serum creatinine, worsening hypertension, and/or recurrent flash pulmonary edema), and all patients underwent multidisciplinary evaluation before stenting and during follow-up.

RESULTS

Follow-up spanned a mean 45.8+/-26.5 months. TVR was needed in 88 (10.03%) of 877 arteries and was best predicted by patient age < or =67 years (OR 2.91, p=0.0001), stent diameter < or =5.0 mm (OR 2.31, p=0.001), solitary functioning kidney (OR 2.01, p=0.048), history of lower extremity peripheral artery disease (OR 1.87, p=0.008), and antecedent history of stroke (OR 1.73, p=0.026).

CONCLUSION

Renal artery stenting appears to be durable, with only 10% of stented arteries requiring TVR during clinically-based long-term follow-up. Arteries with a final stent diameter < or =5.0 mm were more than twice as likely to need TVR, as were patients with a solitary kidney. The authors acknowledge that clinical recurrence is not a surrogate for ultrasound surveillance after renal artery stenting, so prospective controlled trials will be needed to determine risk factors for restenosis.

Renal angioplasty and stenting: long-term results and the potential role of protection devices

Renal angioplasty and stenting have become the first treatments to be proposed to patients presenting with renal artery stenosis. The immediate technical success rate is high, with a low complication rate and good long-term patency. In most reports, renal stenting has been proven to improve blood pressure. However, despite good immediate- and long-term results, postprocedural deterioration of renal function is a concern, and may occur after renal artery angioplasty and stenting in 20 to 40% of patients, which limits the immediate benefits of this technique. Of the causes of this deterioration in renal function, atheroembolism seems to play an important role. Contrary to earlier beliefs that atheroembolization is not an issue during percutaneous catheter interventions, there is now mounting evidence that distal atherosclerotic debris commonly embolizes from lesions in many vascular territories during percutaneous interventions. Atheroembolism seems to be the root cause of many procedural complications wherever atherosclerotic lesions are treated. Distal embolization was first demonstrated in saphenous vein grafts and now, clinical data are proving that similar embolization and distal-organ complications also occur during catheter treatment in certain native coronary lesions, carotid stenting and renal artery stenting, demonstrating the role and efficacy of protection devices to reduce the incidence of end-organ complications. The same protection devices (protection balloon and filters) utilized for coronary or carotid procedures may be used to protect the kidney from atheroembolism. In this review, the authors discuss recently published data concerning the techniques and results of renal angioplasty and stenting procedures performed under protection, and evaluate the benefits of this technique on renal function and its role in the future. Indications for this technique need to be discussed.

Renal artery stenosis: epidemiology, clinical manifestation, and percutaneous endovascular therapy

Renal artery stenosis may cause or deteriorate arterial hypertension and/or renal insufficiency. Technical improvements of diagnostic and interventional endovascular tools have lead to a more widespread use of endoluminal renal artery revascularization and extension of the indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Grüntzig in 1978, numerous single-center studies have reported the beneficial effect of percutaneous transluminal renal angioplasty, and since the early 1990's stenting of renal artery stenosis caused either by atherosclerosis or by fibromuscular dysplasia. This article summarizes the impact of technical improvements of endovascular tools on interventional techniques during the last decade and gives an overview concerning the clinical impact of renal artery revascularization. Despite the absence of sufficient randomized studies, there is nonetheless evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has an impact on blood pressure control, renal function, and left ventricular hypertrophy.

Restenosis after stenting of atherosclerotic renal artery stenosis: Is there a rationale for the use of drug-eluting stents?

Percutaneous stent-angioplasty has become an accepted therapy for the treatment of atherosclerotic renal artery stenosis (RAS) because of higher acute and long-term success rates compared with balloon angioplasty alone. Restenosis rates after successful renal stent placement vary from 6 to 20% and depend mainly on the definition of restenosis and the vessel diameter of the renal artery or stent. We recommend that restenosis should be defined as >70%. The safety and efficacy of drug-eluting stents for the treatment of RAS is poorly defined. The currently partially published GREAT study (Palmaz Genesis peripheral stainless steel balloon expandable stent: comparing a sirolimus-coated vs. a bare stent in REnal Artery Treatment) examined the effect of a sirolimus-coated stent on restenosis rate in 102 patients and found a relative risk reduction of angiographic binary in-stent restenosis by 50% (7% versus 14%, P = ns). Given the lack of outcome data, the considerable expenses associated with drug-eluting stents, morbidity, and cost associated with prolonged dual antithrombotic therapy, the use of drug-eluting stents in RAS should be restricted to clinical trials. This is a review on restenosis rate following renal stenting, its definition, and the potential use for implantation of a drug-eluting stent in RAS, which so far for this indication is not yet commercially available.

Renal artery stenting in solitary functioning kidneys: Technical and clinical results

OBJECTIVE

To evaluate the clinical and technical results of renal artery stenting for the treatment of renovascular hypertension and renal failure in patients with solitary functioning kidney.

MATERIALS AND METHODS

Fifteen patients with solitary functioning kidney underwent renal artery stenting and were followed up for 12-60 months. Before the procedures, systolic and diastolic blood pressures and serum creatinine levels were measured and the number of antihypertensive drugs was recorded and followed up after stenting. In case of restenosis, either in-stent percutaneous transluminal renal angioplasty or stent-in-stent placement was performed.

RESULTS

Primary technical success rate was 100%. One lesion was nonostial while 14 were ostial. Primary patency rates were 100% for 6 months, 92.3% for 12 months, and 69.2% for 24 months. The secondary patency rate at 24 months was 100%. The differences between the baseline and postprocedural values of systolic blood pressures, diastolic blood pressures and the number of antihypertensive drug were statistically significant (P < 0.05), except the values of serum creatinine. Hypertension was cured in 1 (6.7%) patient, improved in 4 (26.6%) and stabilized in 10 (66.7%) patients. Renal function improved in 9 (60%), stabilized in 4 (26.6%), and deteriorated in 2 (13.4%) patients. Minor complication rate was 13.4% and major complication rate was 13.4%.

CONCLUSION

Revascularization of renal artery stenosis using stent in solitary functioning kidneys is a safe and efficient procedure with high primary technical results, low restenosis rates and acceptable complication rates. It has an improving and controlling effect on blood pressure and renal functions.

Impact of Carbon Coating on the Restenosis Rate After Stenting of Atherosclerotic Renal Artery Stenosis

PURPOSE

To investigate the impact of carbofilm coating and low-profile rapid exchange stent devices on the restenosis rate after stent-angioplasty of atherosclerotic renal artery stenosis (RAS).

METHODS

During a 2-year period (7/2002-7/2004), 143 consecutive patients with 179 primary ostial atherosclerotic RAS>or=70% diameter stenosis were treated with stents selected at the discretion of the operator. Eighteen patients (32 lesions) treated with 9 different types of stents were excluded from the analysis, leaving 125 patients (69 men; mean age 67 years, range 42 to 90) with 147 lesions who received either a Radix carbofilm-coated stent in 78 (53%) lesions (68 [54%] patients) or a Palmaz Genesis bare stainless steel stent in 69 (47%) lesions (57 [46%] patients). The target vessel diameter ranged from 5 to 7 mm.

RESULTS

Baseline characteristics were similar in both groups except the mean stent diameter, which was larger in the bare stent cohort (6.4+/-0.7 versus 5.9+/-0.5 mm, p<0.001). Primary success was 100% in both groups; the initial mean diameter stenosis was reduced from 79%+/-14% and 80%+/-14% in the coated versus bare stent groups to 3+/-5% and 2+/-6%, respectively. After a mean follow-up of 22+/-5 months, the restenosis rate was 6.4% for the coated stent and 5.8% for the bare stent (p=0.87). For the entire cohort, restenosis rates varied significantly (p<0.05) according to stent diameter: 19% (5/26) for 5 mm, 4% (3/81) for 6 mm, and 2.5% (1/40) for 7 mm. In a binary logistic regression analysis including carbofilm coating, stent diameter, gender, diabetes, smoking status, and body mass index, stent diameter was the only independent predictor of restenosis (odds ratio 0.12, 95% CI 0.03 to 0.48 [p=0.003] for a 1-mm increase in vessel diameter).

CONCLUSIONS

Using modern low-profile stent devices, carbofilm coating does not significantly reduce the restenosis rate compared to a bare metal stent. With contemporary stent devices, the restenosis rate has been decreasing compared to earlier reports in the literature.

Percutaneous endovascular therapy of renal artery stenosis: technical and clinical developments in the past decade

Renal artery stenosis may initiate or exacerbate arterial hypertension and/or renal insufficiency. During the last decade, technical improvements of diagnostic and interventional endovascular tools have led to more widespread use of endoluminal renal artery revascularization and broader indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Gruntzig in 1978, numerous single-center studies have documented the benefits of percutaneous renal revascularization. In the early 1990s, stent implantation was added to the interventionist's armamentarium for treating renal artery stenosis due to atherosclerosis or fibromuscular dysplasia. The meta-analysis of 3 randomized studies comparing balloon angioplasty with best medical therapy found intervention to be beneficial for blood pressure control but not for preservation of renal function. Despite the absence of randomized studies, there is mounting evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has a positive impact on blood pressure control and renal function. This article summarizes the technical improvements in these endovascular tools during the last decade and gives an overview concerning their clinical impact on renal artery revascularization.

Delicate Percutaneous Renal Artery Stenting Minimizes Postoperative Renal Injury and Protects Kidney in Patients With Severe Atherosclerotic Renal Artery Stenosis and Impaired Renal Function

Percutaneous transluminal renal artery stenting (PTRAS) is associated with declining renal function in a non-negligible portion of patients and is inflicted by different mechanisms, including atheroembolism. This study investigated whether delicate PTRAS to reduce atheroembolism might minimize postoperative renal injury and better preserve renal function. Patients undergoing PTRAS performed by experienced interventional cardiologists, applying coronary intervention concepts, techniques, devices and delicacy principles whenever possible, were prospectively studied. A total of 34 patients (29 M/5 F) with impaired renal function (group A, creatinine 2.4 +/- 0.1 mg/dL) and another 20 patients (16 M/4 F) with normal serum creatinine (group B, baseline creatinine 1.2 +/- 0.0 mg/dL) were studied. PTRAS was successfully performed in all but one group A patient. During a 6-month follow-up, systolic and diastolic blood pressure (130 +/- 2 versus 148 +/- 4 mmHg, P = 0.001 and 70 +/- 2 versus 78 +/- 3 mmHg, P = 0.006) and serum creatinine (2.1 +/- 0.1 versus 2.4 +/- 0.1 mg/dL, P < 0.001) were all significantly lowered in group A patients. Using a 20% change cut-off value, renal function improved in eight (24%), remained unchanged in 24 patients (73%), and deteriorated in only one patient (3%). The corresponding alterations in blood pressure and renal function were insignificant in group B patients. Patients with bilateral involvement (eleven patients) also had significantly lowered serum creatinine on follow-up. In conclusion, delicately practiced PTRAS can reduce the rate of postprocedural renal deterioration in patients with impaired renal function, and should be adopted in every renal intervention.

Transradial Renal Artery Angioplasty and Stenting in a Patient With Leriche Syndrome

Percutaneous interventional procedures in the renal arteries are usually performed employing a femoral or brachial vascular access. In contrast, the transradial approach has been established for coronary angiography and angioplasty. We encountered a patient with Leriche syndrome who had renovascular hypertension ascribed to a severe left renal artery stenosis. To stabilize his blood pressure, we made an attempt to relieve the renal artery stenosis with Leriche syndrome by transradial renal artery angioplasty and stenting, using devices for coronary intervention. The procedure was successful without complications or residual stenosis. His hypertension improved with less antihypertensive medications. This case suggests that the radial approach might become an alternative entry site for renal artery interventions.

Sonographic follow-up after visceral artery stenting

OBJECTIVE

The aim of this study was to evaluate the sonographic features of stents and the flow parameters of the visceral arteries after stent implantation.

METHODS

Since 1996, 34 stenoses of the visceral arteries (2 mesenteric, 4 celiac trunk, and 28 renal arteries) in 28 patients have been treated with metallic stent implantation in the Department of Radiology of Szeged Medical University. All these patients were regularly followed sonographically. For the diagnosis of restenosis, previously published criteria were used.

RESULTS

All the mesenteric and celiac stents could be visualized, but none of the renal stents were clearly seen sonographically. The flow parameters could be established in all cases. Sonographic examination revealed 1 occlusion, 2 restenoses, and 1 stent displacement. All these abnormalities were confirmed by other imaging modalities.

CONCLUSIONS

Sonography is a useful tool in the follow-up of patients after visceral artery stenting. Despite the fact that none of the renal artery stents were visualized directly, the flow parameters could be evaluated, and the pathologic changes were found.

Stent-Supported Angioplasty of Severe Atherosclerotic Renal Artery Stenosis Preserves Renal Function and Improves Blood Pressure Control:Long-term Results From a Prospective Registry of 456 Lesions

PURPOSE

To report a prospective study evaluating the long-term impact of stent-supported angioplasty on renal function and blood pressure control.

METHODS

In a 6-year period, 456 hemodynamically significant de novo renal artery stenoses > or =70% were treated in 340 consecutive hypertensive patients (223 men; mean age 66+/-10 years, range 44-84) with or without impaired renal function. Baseline data on serum creatinine (sCr), intrarenal resistance index, ambulatory 24-hour blood pressure monitoring, and documentation of the number and dose of antihypertensive drugs were compared to values obtained during follow-up. The primary endpoint was a 10% decrease in sCr; the glomerular filtration rate and changes in blood pressure control were additional outcome measures.

RESULTS

During a mean follow-up of 34+/-20 months, sCr decreased significantly from 1.45+/-0.87 to 1.39+/-0.73 mg/dL (p=0.048). In 34% of the patients, sCr decreased >10%, 39% were unchanged, and 27% had an increase >10%. Glomerular filtration rate increased from 59+/-26 to 62+/-26 mL/min/1.73 m(2) (p=0.6). Systolic, diastolic, and mean blood pressure measurements significantly improved immediately after the intervention (132/72/93 versus 144/79/102 mmHg at baseline, p<0.0001) and remained improved during follow-up (p<0.0001). Blood pressure control was improved in 46%, unchanged in 43%, and deteriorated in 11%. Baseline sCr, bilateral intervention, percent diameter stenosis, and 3-vessel coronary disease were independent predictors of improved renal function during follow-up; the number of antihypertensive drugs taken before the intervention predicted improved blood pressure control.

CONCLUSIONS

Stent-supported angioplasty of renal artery stenoses preserves renal function and improves blood pressure control in a broader spectrum of patients than previously thought.

Predictors of Improved Renal Function After Percutaneous Stent-Supported Angioplasty of Severe Atherosclerotic Ostial Renal Artery Stenosis

BACKGROUND

Percutaneous stent-supported angioplasty is a treatment option for atherosclerotic ostial renal artery stenosis. Improvement of renal function by such intervention, however, is controversial and thought to be limited to specific subsets, such as nondiabetic patients and bilateral stenoses. In this prospective study, we investigated predictors for improvement of renal function and blood pressure after renal artery stent placement.

METHODS AND RESULTS

The study included 215 consecutive patients with ostial renal artery stenosis of > or =70% diameter stenosis undergoing stent-supported angioplasty. The primary end point was decrease in serum creatinine concentration at 1 year; the secondary end point, decrease in average mean arterial blood pressure assessed by 24-hour monitoring. One-year follow-up was complete in 191 surviving patients. In 52% (99/191) of the patients, serum creatinine concentration decreased during 1-year follow-up. Median serum creatinine concentration dropped significantly from 1.21 mg/dL (quartiles: 0.92, 1.60 mg/dL) at baseline to 1.10 mg/dL (quartiles: 0.88, 1.50 mg/dL) at 1 year (P=0.047). On average, mean arterial blood pressure decreased significantly, from 102+/-12 mm Hg (mean+/-SD) at baseline to 92+/-10 mm Hg at 1 year (P<0.001). Significant independent predictors of improved renal function were baseline serum creatinine (odds ratio [95% CI], 2.58 [1.35 to 4.94], P=0.004) and left ventricular function (OR 1.51 [1.04 to 2.21], P=0.032). Female sex, high baseline mean blood pressure, and normal renal parenchymal thickness were independent predictors for decreased mean blood pressure.

CONCLUSIONS

Stent-supported angioplasty for severe ostial renal artery stenosis improves renal function and blood pressure in a broader spectrum of patients than previously thought.

Renal angioplasty and stenting with distal protection of the main renal artery in ischemic nephropathy: early experience

PURPOSE

We present a retrospective review of a single tertiary hospital experience in renal artery stent revascularization with distal protection in patients with ischemic nephropathy. The objectives of the study included preliminary assessment of the effect of distal protection on procedure-related acute deterioration in renal function and on renal salvage.

MATERIAL AND METHODS

All patients had significant atherosclerotic main renal artery stenosis, documented at preprocedural imaging, and a degree of chronic renal impairment before revascularization. Forty-six renal arteries were treated in 37 patients with preprocedural renal impairment, which was mild in 10 patients, moderate in 19 patients, and severe in 8 patients. Median patient age was 72 years (range, 59-85 years). All patients underwent primary stenting of renal artery ostial stenoses with adjuvant use of a filter device (Angioguard guide wire system; Cordis Corp, Division of Johnson & Johnson, Miami, Fla) in the distal main renal artery. The filter baskets were recaptured for pathologic analysis.

RESULTS

Overall, in 95% of patients, including all patients with preprocedural mild or moderate renal impairment, renal function was stabilized or improved after revascularization. In 5% of patients decline in renal function was unchanged. No patients had acute postprocedural deterioration. Mean follow-up was 12.5 months (range, 2-28 months). These results are better than in most reports in the literature and also better than in a historical group of similar patients with ischemic nephropathy who underwent stent revascularization without distal protection at the same institution. The improved results are thought to be due to prevention of cholesterol atheroembolization during the procedure by the distal filter baskets. Sixty-five percent of the distal protection baskets contained embolic material, including fresh thrombus, chronic thrombus, atheromatous fragments, and cholesterol clefts.

CONCLUSION

A distal protection device may significantly improve results during stent revascularization. There are a number of unique demands on a renal protection device, and the ideal device has not yet been developed.

Renal angioplasty and stenting under protection: The way for the future?

The purpose of this study was to evaluate the feasibility and safety of renal artery angioplasty and stenting utilizing a distal protection device to reduce the risk of intraprocedural artery embolism and avoid deterioration of the renal function. Fifty-six hypertensive patients (32 men; mean age, 66 +/- 11.8 years; range, 22-87) with atherosclerotic renal artery stenosis (8 bilateral) underwent angioplasty and stenting with distal protection in 65 renal arteries (58 ostial lesions). Five patients had a solitary kidney, 18 a renal insufficiency. The lesion was crossed either with a GuardWire temporary occlusion balloon (n = 38), which was inflated to provide parenchyma protection or with a filter (EPI Filter; n = 26), or with Angioguard (n = 1), which allows a continuous flow. Generated debris was aspirated and analyzed. Blood pressure and serum creatinine levels were followed. Immediate technical success was 100%. All lesions except one were stented, either directly (43 ostial lesions) or after predilatation (22 ostial lesions). Visible debris were aspirated with the PercuSurge in all patients or removed with filters in 80% of the patients. Mean particle number and diameter were 98.1 +/- 60.0 per procedure (range, 13-208) and 201.0 +/- 76.0 microm (range, 38-6,206), respectively. Mean renal artery occlusion time was 6.55 +/- 2.46 min (range, 2.29-13.21) with the PercuSurge device. Mean time in situ (filters) was 4.25 +/- 1.12 min. Mean follow-up was 22.6 +/- 17.6 months (range, 1-47). Systolic and diastolic blood pressure declined from 169.0 +/- 15.2 and 104.0 +/- 13.0 mm Hg, respectively, to 149.7 +/- 12.4 and 92.7 +/- 6.7 mm Hg after the procedure. The mean creatinine level remains constant during the follow-up. At 6-month follow-up (45 patients), renal function did not deteriorate in any patient, whereas 8 patients with baseline renal insufficiency improved after the procedure. At 3 years (19 patients), renal function deteriorated only in 1 patient with renal insufficiency and in 1 patient treated for bilateral renal stenosis, one side without protection. These preliminary results suggest the feasibility and safety of distal protection during renal interventions to protect against atheroembolism and to avoid renal function deterioration. This technique's beneficial effects should be evaluated by randomized studies.

Guidelines for the Reporting of Renal Artery Revascularization in Clinical Trials

Although the treatment of atherosclerotic renal artery stenosis with use of percutaneous angioplasty, stent placement, and surgical revascularization has gained widespread use, there exist few prospective randomized controlled trials (RCTs) comparing these techniques to each other or against the standard of medical management alone. To facilitate this process as well as help answer many important questions regarding the appropriate application of renal revascularization, well-designed and rigorously conducted trials are needed. These trials must have clearly defined goals and must be sufficiently sized and performed so as to withstand intensive outcomes assessment. Toward this end, this document provides guidelines and definitions for the design, conduct, evaluation, and reporting of renal artery revascularization RCTs. In addition, areas of critically necessary renal artery revascularization investigation are identified. It is hoped that this information will be valuable to the investigator wishing to conduct research in this important area.

Gold coating and restenosis after primary stenting of ostial renal artery stenosis

Predictors of restenosis after stent angioplasty of ostial renal artery stenosis (RAS) and long-term technical success, particularly the influence of gold coating, are unknown. During a 4-year period (1996-2000), we treated 156 consecutive patients with 219 ostial RAS of > or = 70% diameter stenosis. Gold-coated stents were used in 29% of RAS (n = 64); the vessel diameter ranged from 3 to 9 mm. The restenosis rate was 11.4% at 12 months, 12.2% for gold-coated stents and 11.1% for noncoated stents. Restenosis rates were 16% for < or = 4 mm, 17% for 5 mm, 10% for 6 mm, and 0% for > or = 7 mm (P < or = 0.05). In a backward stepwise logistic regression analysis including gold coating, vessel diameter, gender, diabetes, smoking status, as well as lesion diameter stenosis before and after stenting, vessel diameter was found the only independent predictor of restenosis (odds ratio = 0.57; 95% CI = 0.35-0.93; P = 0.02, for an increase in vessel diameter of 1 mm). Gold coating was not a significant predictor (odds ratio = 1.09; 95% CI = 0.39-3.03; P = 0.87). Seven major (4.5%) complications occurred. There were no procedural fatalities. The restenosis rate after stent angioplasty of ostial RAS is influenced by the vessel diameter but not by gold coating.

Renal artery stenosis: when to intervene?

Indications and timing of revascularization for atherosclerotic renal artery stenosis are topics of considerable controversy. Labile hypertension, progressive renal failure, and flash pulmonary edema may be strong indications for revascularization, yet revascularization may carry significant morbidity and mortality risks. Medical therapy alone, however, may also risk deterioration of renal function with worsening morbidity and mortality. We report a case of renal artery stenosis illustrating some of the complexities of decision-making, the limitations of angiography, and the importance of physiologic testing.

The diagnosis and management of renovascular disease: a primary care perspective. Part II. Issues in management

Renovascular disease is a complex disorder, most commonly caused by fibromuscular dysplasia and atherosclerotic disease. It usually presents in one of three forms: asymptomatic renal artery stenosis, renovascular hypertension, or ischemic nephropathy. This complexity may make diagnostic and management decisions difficult for the primary care physician. In Part I of this review (presented in the May/June 2003 issue of The JCH), the authors discussed when to consider and how to go about making a diagnosis of renovascular disease. In Part II, the authors review the management of this complex condition. There is a debate concerning the optimal treatment of patients with renovascular disease. Management options include medical, surgical, or percutaneous approaches (angioplasty and stenting). Generally in patients with fibromuscular disease, the results of surgery and percutaneous approaches appear superior. In patients with atherosclerotic disease, the data are less consistent, and there does appear to be a group of patients who will respond well to medical management. A potential management algorithm is presented.

Atherosclerotic Renal Artery Stenosis

The clinical diagnosis of renal artery stenosis relies on a high index of suspicion and confirmation by noninvasive imaging modalities. There are three distinct clinical syndromes associated with renal artery stenosis: renin-dependent hypertension, essential hypertension, and ischemic nephropathy. Clinical features that should heighten suspicion for renal artery stenosis include abrupt-onset or accelerated hypertension at any age, unexplained acute or chronic azotemia, azotemia induced by angiotensin-converting enzyme (ACE) inhibitors, asymmetric renal dimensions, and congestive heart failure with normal ventricular function. Patients with true renin-dependent (renovascular) hypertension are typically young or middle-age women with renal fibromuscular dysplasia (FMD). Initial therapy for renovascular hypertension associated with FMD is an ACE inhibitor; refractory hypertension responds readily to balloon angioplasty without stenting. Elderly patients with generalized atherosclerosis and hypertension often have atherosclerotic renal artery stenosis (ARAS); hypertension in these patients is usually not renin dependent (ie, essential hypertension). Hypertension alone, even if treated with multiple medications, is not a compelling indication for renal artery revascularization; these patients should be treated aggressively with antihypertensive medical therapy. Renal artery revascularization with stenting may be considered for refractory severe hypertension, and would be expected to improve blood control and modestly reduce medication requirements. Renal revascularization rarely cures hypertension in patients with ARAS. Patients with ARAS, hypertension, and end-organ injury should be considered for renal revascularization. Manifestations of end-organ injury include nonischemic pulmonary edema; hypertensive crisis associated with acute coronary syndrome, aortic dissection, or neurologic impairment; and renal insufficiency. Ischemic nephropathy is best treated before the development of advanced renal failure. The best candidates for revascularization are those with baseline serum creatinine less than 2.0 mg/dL, bilateral renal artery stenosis, normal renal resistive indices, no proteinuria, and one or more manifestations of end-organ injury. In these patients, renal revascularization is best accomplished by stenting, although surgical revascularization may be considered in patients with concomitant severe aortic aneurysmal or occlusive disease.

Stent angioplasty of severe atherosclerotic ostial renal artery stenosis in patients with diabetes mellitus and nephrosclerosis

Atherosclerotic renal artery stenosis (ARAS) may lead to deterioration of renal function or hypertension. The clinical outcome after stent angioplasty of ARAS on renal function and blood pressure control in patients with diabetes and nephrosclerosis is the subject of some controversy. We have analyzed the results of our single-center experience with stent angioplasty for severe (>/= 70%) ostial ARAS and present here the results of a subgroup analysis of those patients who had diabetes mellitus and nephrosclerosis. From 1996 to 2001, 241 patients underwent stent angioplasty for the treatment of ARAS at our center. Of these, 99 patients had diabetes mellitus (41%) and 176 patients (73%) had nephrosclerosis defined as intrarenal resistance index (RI) >/= 0.7 diagnosed by duplex ultrasound. All lesions (n = 355) were treated successfully. Mean blood pressure at baseline was comparable and significantly improved immediately after the intervention in all groups (nondiabetics: 102 +/- 12 to 93 +/- 10 mm Hg; diabetics: 102 +/- 14 to 93 +/- 11 mm Hg; RI < 0.7: 105 +/- 13 to 95 +/- 10 mm Hg; RI = 0.7-0.8: 100 +/- 12 to 92 +/- 10 mm Hg; RI > 0.8: 102 +/- 15 to 92 +/- 11 mm Hg; P < 0.0001 each). Baseline serum creatinine was not significantly lower in nondiabetics compared to diabetics (1.46 +/- 0.9 vs. 1.62 +/- 1.2 mg %; P < 0.05) and increased in patients with nephrosclerosis (RI < 0.7: 1.18 +/- 0.6 mg %; RI = 0.7-0.8: 1.57 +/- 1.1 mg %; RI > 0.8: 1.96 +/- 1.6 mg %). Except for patients without nephrosclerosis who had a normal baseline creatinine, serum creatinine decreased significantly in all subgroups during follow-up. Stent angioplasty of ARAS offers favorable acute and long-term clinical results for the preservation of the renal function and for blood pressure control in patients with diabetes mellitus and nephrosclerosis.

Atherosclerotic renal arterial stenosis: clinical outcomes of stent placement for hypertension and renal failure

PURPOSE

To assess technical success rates and long-term clinical outcomes of primary renal arterial stent placement in atherosclerotic renal arterial stenosis (RAS).

MATERIALS AND METHODS

Primary stent placement was performed in 100 consecutive patients with atherosclerotic RAS. Indications for treatment were resistant hypertension (n = 25), impaired renal function, (n = 50), and both (n = 25). Immediate technical results were evaluated with angiography. Clinical outcomes were assessed with serial systolic and diastolic blood pressure and serum creatinine values obtained from retrospective review of case notes. Results obtained every 6 months after the procedure were compared with those obtained at the time of the procedure with the paired t test. Radiologic reports were evaluated for immediate and case notes for delayed complications.

RESULTS

Technical success was achieved in 120 (95.2%) of 126 RAS in 95 patients. Mean follow-up was 25 months (median, 24 months; range, 1-66 months). Resistant hypertension was cured in two (4.2%) of 48 patients, had improved in 38 (79.1%), and had failed to respond to treatment in eight (16.7%). Mean systolic and diastolic blood pressures were significantly lower at 6, 12, 18, 24, and 30 months (P <.01) than before the procedure. Among 65 patients treated for renal impairment, renal function improved in 20 (30.8%), stabilized in 25 (41.7%), and continued to deteriorate in 20 (30.8%). The mean serum creatinine level did not show significant change with time for this group. In the improved subgroup, it was significantly higher at 6, 12, 18, 24, 36, and 42 months (P <.05) than prior to the procedure. Procedure-related complications occurred in 18 (18%) cases: Ten were minor and self-limiting and eight were major and included two procedure-related deaths.

CONCLUSION

In atherosclerotic RAS, primary stent deployment has a high technical success rate, producing clinical benefits in the majority of patients when performed for resistant hypertension and recovery of renal function.

Repeated intervention for in-stent restenosis of the renal arteries

PURPOSE

To assess the long-term technical success of repeated endovascular intervention in stenosed renal artery stents.

MATERIALS AND METHODS

Fifteen patients with stenoses >or=50% in a renal stent placed because of an ostial atherosclerotic renal artery stenosis were included in this study. In the presence of increased blood pressure or decreased renal function, the in-stent restenosis was treated with percutaneous transluminal angioplasty (PTA) in the stent or placement of a second stent if the stenosis was located too distally in the stent. The results of these repeat interventions were evaluated by angiography.

RESULTS

The 15 patients had a total of 20 stenosed stents. Eighteen of these in-stent stenoses were treated with PTA and two were treated with placement of a second stent. Angiographic follow-up was available in 16 arteries, showing in-stent restenosis in four (25%; mean follow-up, 11 mo). The cumulative patency rates after repeat endoluminal intervention were 93% (95% CI: 80%-106%) and 76% (95% CI: 52%-101%) after 6 and 12 months, respectively. Renal function remained stable or improved in most patients (80%) after repeated intervention in the stent, and hypertension was classified as improved or cured in 47% of patients after 1 year.

CONCLUSION

Patients with stenosed renal artery stents can be treated successfully with PTA in a majority of cases, with a long-term success rate of 75% and stable renal function 1 year after repeated intervention.

Guidelines for the reporting of renal artery revascularization in clinical trials

Although the treatment of atherosclerotic renal artery stenosis with use of percutaneous angioplasty, stent placement, and surgical revascularization has gained widespread use, there exist few prospective randomized controlled trials (RCTs) comparing these techniques to each other or against the standard of medical management alone. To facilitate this process as well as help answer many important questions regarding the appropriate application of renal revascularization, well-designed and rigorously conducted trials are needed. These trials must have clearly defined goals and must be sufficiently sized and performed so as to withstand intensive outcomes assessment. Toward this end, this document provides guidelines and definitions for the design, conduct, evaluation, and reporting of renal artery revascularization RCTs. In addition, areas of critically necessary renal artery revascularization investigation are identified. It is hoped that this information will be valuable to the investigator wishing to conduct research in this important area.

Incidental renal artery stenosis among a prospective cohort of hypertensive patients undergoing coronary angiography

OBJECTIVE

To determine the feasibility, safety, and clinical yield of angiographic screening among hypertensive patients undergoing coronary angiography.

PATIENTS AND METHODS

This study was a prospective cohort analysis of hypertensive patients who underwent cardiac catheterization at a tertiary care referral center from July 1998 to March 1999. Abdominal aortography was performed to screen for renal artery stenosis, the percentage of which was measured.

RESULTS

The mean +/- SD age of the 297 study patients was 64.9+/-10.2 years; 58.6% were male, and 98.0% were white. Mean +/- SD systolic/diastolic blood pressure was 142.8+/-22.5/79.6+/-11.4 mm Hg. Aortography required a mean incremental dose of 62+/-9 mL of nonionic contrast agent. No complications were attributable to aortography. Of 680 renal arteries, 611 (90%) were visualized adequately. Also, 53% of patients had normal renal arteries, 28% had stenoses less than 50%, and 19.2% had stenoses of 50% or more. Renal artery stenosis was bilateral in 3.7% of patients and high grade (>70% stenosis) in 7%. Patients with renal artery stenosis were more likely to have had a previous coronary intervention. In multivariate analysis, systolic blood pressure (odds ratio [OR], 1.2; 95% confidence interval [CI], 1.03-138; P=.02), history of stroke or transient ischemic attack (OR, 2.7; 95% CI, 1.27-5.78; P=.01), and cancer (OR, 2.0; 95% CI, 1.02-3.82; P=.04) independently correlated with renal artery stenosis of 50% or more.

CONCLUSION

The prevalence of incidental renal artery stenosis among hypertensive patients undergoing coronary catheterization is significant. Therefore, screening abdominal aortography should be considered in these patients to better define their risk of cardiovascular complications.

Renal artery stenosis: duplex US after angioplasty and stent placement

PURPOSE

To evaluate the hemodynamic outcome of technically successful percutaneous transluminal renal artery angioplasty and stent placement (PTRAS) with duplex ultrasonography (US).

MATERIALS AND METHODS

Eighteen patients who underwent PTRAS in 22 renal arteries were prospectively examined. All had abnormal preprocedural duplex US findings. Those who had significant renal artery stenosis (>70%) at angiography and underwent technically successful percutaneous interventions were enrolled. Standard intrarenal duplex US parameters (acceleration index [AI], acceleration time, waveform morphology grade, and resistive index) were compared before and after interventions.

RESULTS

A significant AI increase occurred after PTRAS (9.02 m/sec(2) +/- 4.85 [SD]), as compared with before intervention (2.34 m/sec(2) +/- 2.03; P <.001). Acceleration time significantly decreased from 0.084 second +/- 0.049 to 0.032 second +/- 0.008 (P <.01). There was also a significant resistive index increase from 0.69 +/- 0.12 to 0.79 +/- 0.12 (P <.01). Abnormal waveform morphology (modified Halpern waveform grade 3-6) was present in 19 (86%) of 22 intrarenal arteries prior to intervention, as compared with one (5%) after PTRAS (P <.001). In the instance in which an abnormal waveform persisted after intervention, waveform morphology improved from grade 6 to grade 3, with a concomitant AI increase from 0.96 to 5.1 m/sec(2).

CONCLUSION

The findings suggest an important potential role for duplex US in noninvasive assessment of the immediate hemodynamic outcome and long-term follow-up of PTRAS.

Protected renal stenting with the PercuSurge GuardWire device: a pilot study

PURPOSE

To evaluate the feasibility and safety of renal artery angioplasty and stenting utilizing a distal protection device to reduce the risk of intraprocedural atheroembolism.

METHODS

Twenty-eight hypertensive patients (18 men; mean age 71.3 +/- 8.6 years, range 49-87) with atherosclerotic renal artery stenosis (4 bilateral) underwent angioplasty and stenting with distal protection in 32 renal arteries (29 ostial lesions). The lesion was crossed with a GuardWire temporary occlusion balloon, which was inflated to provide parenchymal protection. Generated debris was aspirated and analyzed. Blood pressure and serum creatinine levels were followed.

RESULTS

Immediate technical success was 100%. All lesions were stented, either directly (14 ostial lesions), after predilation (15 ostial lesions), or owing to suboptimal angioplasty (3 nonostial lesions). Visible debris was aspirated from all patients. Mean particle number and diameter were 98.1 +/- 60.0 per procedure (range 13-208) and 201.2 +/- 76.0 microm (range 38-6206), respectively. Mean renal artery occlusion time was 6.55 +/- 2.46 min (range 2.29-13.21). Mean follow-up was 6.7 +/- 2.9 months (range 2-17). Systolic and diastolic blood pressure declined from 167.0 +/- 15.2 and 103.0 +/- 12.0 mm Hg, respectively, to 154.7 +/- 12.3 and 93.2 +/- 6.8 mm Hg after the procedure. The mean creatinine level dropped from 1.34 +/- 0.35 mg/dL preprocedurally to 1.22 +/- 0.36 mg/dL at 24 hours and remained constant. At 6-month follow-up, renal function did not deteriorate in any patient, whereas 5 patients with baseline renal insufficiency improved after the procedure.

CONCLUSIONS

These preliminary results suggest the feasibility and safety of distal balloon occlusion during renal interventions to protect against atheroembolism. This technique's beneficial effects should be evaluated by randomized studies.

Endovascular revascularization of renal artery stenosis: technical and clinical results

PURPOSE

The natural history of renal artery stenosis is progression with subsequent deterioration of kidney function and development of renovascular hypertension. Percutaneous transluminal renal angioplasty is effective in the treatment of nonostial lesions but less effective for ostial stenoses. Because of the poor technical success experienced with percutaneous transluminal renal angioplasty, stenting of ostial stenoses is becoming the standard of endovascular care. In this retrospective study we analyzed the technical and clinical outcomes after renal artery stenting in 73 consecutive patients.

PATIENTS AND METHODS

From July 1992 to January 1999, 88 Palmaz stents were deployed in 85 renal artery stenoses in 73 patients, with a mean age of 67.9 +/- 9.4 years. Twelve patients (16%) underwent bilateral stent placement. Atheromatous lesions were the most prevalent (99%: 82% ostial, 16% nonostial). Most stents were implanted for suboptimal balloon dilation (52%) or dissection (24%). Mean percent stenosis was 86% +/- 12%. Renal insufficiency (creatinine level > or = 1.5 mg/dL) was present in 50 (68%) patients, and uncontrolled hypertension (systolic > or = 160 mm Hg or diastolic > or = 90 mm Hg with more than two medications) was present in 57 (78%).

RESULTS

Primary technical success was achieved in 89%. At the initial procedure, three additional stents were placed for residual stenoses, and urokinase was used to treat one intraprocedural stent thrombosis, resulting in an assisted primary technical success rate of 94%. Major complications occurred in 9.1% of stents placed: access artery thrombosis (n = 4), renal artery extravasation (n = 1), renal artery thrombosis (n = 1), and hematoma requiring operation (n = 2). Long-term clinical data were available on 69 (95%) patients at 20 +/- 17 months. Overall, a significant decrease in systolic and diastolic pressures (P <.001) and reduction of medication (P <.01) were noted without a change in renal function (P = NS). Angiography was performed on 22 patients at 11.3 +/- 10.3 months for persistent or worsening renal function or hypertension or for other reasons; 10 patients had significant restenoses in 14 renal arteries.

CONCLUSION

Our retrospective analysis demonstrates that endovascular stenting of renal artery stenosis in patients with poorly controlled hypertension or deteriorating renal function is a safe and effective alternative treatment to surgical management.

Renal artery stenosis treated with stent deployment: indications, technique, and outcome for 108 patients

From January 1993 to May 1996, 108 patients (64 men, 44 women; mean age, 72 years; age range, 37 to 87 years) underwent 125 percutaneous transluminal angioplasties and stent implantations primarily for atherosclerotic lesions of the renal artery. Sixty-four patients underwent treatment for renovascular hypertension (two antihypertensive medications or more), 32 patients underwent treatment for a combination of hypertension and renal failure (serum creatinine level >/=1.6 mg/dL), and a small group of six patients (5%) without hypertension or diminished renal function underwent treatment to prevent the progression to renal artery occlusion and kidney loss. Thirty-three patients (31%) had renovascular hypertension that was classified as severe on three or more medications, 31 patients (29%) had renovascular hypertension that was classified as moderate on two medications, and 38 patients (35%) had renovascular hypertension that was classified in the mild group on a single antihypertensive agent. Stenotic lesions were located at the ostium of the renal artery in 82 cases (65%) and were ostial-adjacent (<5 mm from renal ostium) in the other 43 cases (34%). A total of 125 stents were deployed in 125 arteries (procedural success 97.6%). Renovascular hypertension either was cured or was improved in 73 patients (68%), with 14 patients (13%) considered cured (normotensive on no medications). The conditions of 29 patients (27%) were unchanged, and 6 patients (5%) had worsening hypertension after surgery. We were unable to demonstrate a statistically significant improvement in serum creatinine levels after renal artery balloon angioplasty/stenting. Complications occurred in a total of nine cases (7.2%), six of which were related to technical problems. One patient had worsening renal insufficiency caused by contrast agent, and another patient had a perinephric hematoma develop that necessitated evacuation. There were four postoperative deaths (30-day mortality). Two of these deaths were caused by postoperative myocardial infarction. The other two patients had progressive renal failure develop that necessitated dialysis. These patients later died of the disease process despite supportive care. Follow-up renal artery duplex scan studies and angiograms were available on 96 patients (76%). The mean peak systolic renal/aortic ratio on duplex scanning was 2.2. Life-table analysis yielded a 74% primary patency rate and an 85% secondary patency rate at 36 months. This retrospective analysis showed the effectiveness of combining percutaneous transluminal angioplasty with stent deployment for significant renal artery stenosis to treat renovascular hypertension.

Stent placement for treatment of renal artery stenosis guided by intravascular ultrasound

PURPOSE

To study the impact of intravascular ultrasound (IVUS) during renal artery stent placement.

MATERIALS AND METHODS

Patients (n = 22) with atherosclerotic renal artery stenosis were studied with IVUS after predilation and after angiographically successful stent deployment (diameter stenosis < 10%). After predilation, IVUS was used to assess whether the balloon size selected angiographically was correct (discrepancy balloon-reference lumen diameter < 20%). After stent placement, IVUS images were assessed for (i) complete stent-vessel wall apposition; (ii) complete stent expansion (discrepancy stent-reference lumen diameter < 20%), and (iii) complete lesion covering by the stent. Modification based on IVUS included selection of a larger balloon, additional dilation, and placement of a second stent. Clinical outcome was based on blood pressure, amount of antihypertensive drugs, and glomerular filtration rate during follow-up of 3 months.

RESULTS

Stent placement and ultrasound imaging were completed successfully in 18 patients. After predilation, IVUS warranted the use of a larger balloon in five patients. After stent placement, incomplete stent apposition (n = 1), discrepancy between stent and reference lumen diameter (n = 3), and lesion distal to the stent (n = 2) seen on IVUS were treated with additional dilation in five patients and with a second stent in one patient. A larger balloon was used in three patients. Mean blood pressure and amount of antihypertensive drugs decreased (P < .05).

CONCLUSIONS

In a number of patients, IVUS monitoring during renal artery stent placement resulted in additional lumen enlargement not considered necessary at angiography.