Angioplasty with stent in renal artery stenosis: our experience

Rev Chil Radiol 2016; 22(1): 13-19. Angioplasty with stent in renal artery stenosis: our experience Johanna Marcela Vasquez Veloza *, José Luis Abades Vázquez, José Luis Cordero Castro. Interventional Radiology, San Pedro of La Rioja Hospital, Logrono, Spain. Abstract In this study we provide the results and effectiveness of angioplasty with stent in patients with renal artery stenosis who presented as well with a poorly controlled or refractory hypertension and renal failure. Retrospective study including 16 patients treated by angioplasty with stent. Blood pressure and renal function was monitored in the first 24 hr, 6 month and 12 month follow-ups after angioplasty. Reduction of systolic blood pressure from170 mm Hg to 145 mm Hg was achieved n the first 24 hrs, and to 138 mm Hg in the control at 12 months; the diastolic blood pressure increased from 95 mm Hg to 77 mm Hg in the first 24 hrs, and to 70 mm Hg in the control at 12 months. Renal function remained stable. Keywords: Renal artery stenosis; Angioplasty; Stent Introduction Renal artery stenosis (RAS) is a disease that in 90% of cases is secondary to atherosclerosis, affecting the ostium (80-85%) (Figure 1) or the proximal third of the renal artery (Figure 2). Figure 1 A selective aortogram and arteriography of the right renal artery was performed via the left femoral artery, with significant stenosis of the ostium being visible. Figure 2 Selective aortogram and arteriography of left renal artery is performed via the right femoral artery, with stenosis approximately 1 cm distal to the ostium being visible. The stenosis causes a reduction of 50% in the diameter of the artery and 75% of the area thereof. Its prevalence increases with age, especially in subjects with morbidity and mortality associated factors, such as diabetes mellitus (DM), the aortoiliac occlusive disease, arterial hypertension (high blood pressure - HBP) or heart disease. Progression is from 50% in the following 5 years after diagnosis, with occlusion from 3% to 16% and renal atrophy in 21% of the patients with stenosis greater than 60% (1). Stenosis of the renal artery can cause chronic renal failure if it affects both renal arteries, or if the hypertension associated with this condition is prolonged or critical. This can be serious in cases where it is accompanied with HBP, and sometimes accelerated or malignant, but often it is indistinguishable from essential HBP (1). As for the diagnosis of renal artery stenosis, Doppler ultrasound is the first screening test (2), as it allows for the identification of subclinical atheromatosis in the different vascular territories, renal disorders and renal artery stenosis (3), allowing for the evaluation of the increase of peak systolic velocity above 180 cm/s, being a good parameter to detect a stenosis greater than 60% (4-11). Another parameter used is the resistance index >0.8, allowing for the identification of the patients in whom revascularization will not improve kidney function, blood pressure or kidney survival (3,4). But it must be taken into account that it is Received 5th February 2016; accepted 25th February 2016. Available on internet 5th April 2016. * Author for correspondence. Email address: jmache@gmail.com (J.M. Vasquez Veloza). 2016 SOCHRADI. Published by Elsevier Spain, S.L.U. This is an Open Access article under license CC BY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/). 13

J.M. Vasquez Veloza et al. operator-dependent, and in some cases can be difficult to evaluate, such as in obese patients or those with abundant intestinal gas, and it also does not allow for evaluation of the accessory renal arteries (5). Magnetic resonance angiogram and CT angiography are methods with high a sensitivity and specificity (more than 90%), used when the creatinine clearance exceeds 30 ml/min and 60 ml/min, respectively. Their main disadvantages are based on the limited capacity they have to objectify lesions that are not in the ostium, lesions of the accessory arteries and the respiratory or peristaltic artifacts (6). Renal angiography is used in patients with inconclusive imaging studies, in renovascular hypertension and renal failure due to renal artery stenosis (7). Contraindications are uncorrectable coagulopathy, proven allergy to iodinated contrast and bad vascular access. With this technique, data for the severity of the arterial stenosis and commitment of its branches can be obtained, in order to determine the best revascularization strategy. Even so, this technique is not without risk and may even worsen renal function, especially in diabetic patients or those who previously had an impaired renal function (8). Treatment of RAS helps to improve or in some cases cure hypertension and regulates renal function. However, its invasive treatment consists of 2 procedures: surgery and angioplasty. Surgical repair used primarily in patients who want to correct at the same time an aortic aneurysm, has a preoperative mortality from 2.1% to 6.1% when bypasses are implanted, and 4.7% when endarterectomy is performed. Reoperation at 5 years is from 5% to 15% in treated patients, and the survival rate is from 65% to 81% (9). Percutaneous angioplasty with stenting is a safe procedure, with low morbidity and high success rate in selected patients, as inpatient mortality is 0.5%, but the rate of restenosis remains a disadvantage, because it presents values between 11% to 23% at 5 years (7,8). The aim of this study is to verify the effectiveness of angioplasty with stenting as a treatment for renal artery stenosis using the results obtained in our institution. Materials and methods Study of retrospective case series, in which all patients diagnosed with significant and critical renal artery stenosis, operated between the 30th april 2007 to 30th april 2015 with angioplasty and stent implantation were included, yielding a population target of 16 patients in total. Patients had renal ultrasound with doppler, where renal artery stenosis was confirmed by the aforementioned parameters. Not all of the ultrasound reports had renal measurements, so that criterion is not taken into account in the study. Rev Chil Radiol 2016; 22(1): 13-19. All of the patients underwent renal arteriography for correct diagnosis and to assess the degree of stenosis, considered significant when occlusion of the vessel lumen was between 50% to 80%, and critical when it was greater than 80% (Figure 3). Figure 3 A. Selective aortogram and arteriography of the right renal artery was performed via the left femoral artery, objectifying critical stenosis of the proximal third with ostium integrity. The left renal artery has early bifurcation with no signs of stenosis. B. After the infusion of 5000 IU heparin the 5 20 mm metal prosthesis is implanted with a satisfactory angiographic result. To perform the procedure, all patients received hydration protocol such as nephroprotective. It was performed via the femoral artery under local anaesthesia. Immediately, 5,000 IU of heparin was administered intravenously prior to the start of the intervention. Nonionic contrast medium was used during angioplasty. Subsequently patients received 75 mg of clopidogrel for a month and 100 mg acetylsalicylic acid for life. Angiographically diagnosed lesions were classified as ostial type lesion, those which are located in the first 5 mm into the main artery, and as not ostial lesion those found after the first 5 mm of the main artery. Herculink stents were used in 100% of the cases, most patients with a diameter of 6 mm and longitude of 20 mm (Table 1). After the angioplasty was performed renal function was assessed via plasma creatinine levels during their hospital stay. Hypertension stage was evaluated according to the classification by the National Committee of the United States, where a systolic blood pressure (SBP) less than 120 mm Hg and a diastolic blood pressure (DBP) of less than 80 mm Hg is defined as normotensive, SBP between 120-139 mm Hg or DBP between 80-89 mm Hg is defined as pre-hypertension, SBP between 14

Rev Chil Radiol 2016; 22(1): 13-19. Table 1. Characteristics of the renal angioplasty stent Herculink Stent 17 Diameter 5 mm 8 (47%) 6 mm 9 (53%) Length 18 mm 4 (23%) 20 mm 12 (71%) 22 mm 1 (6%) obesity in 2 patients (12%) were taken into consideration. The majority of the patients were in functional class I, and mean serum creatinine was 1.83 mg/dl. No patient had previously been treated for renal angioplasty with stent. Fourteen patients were taking antihypertensive medication of different classes including diuretics, with an average of 2 drugs per patient (Table 2). Ten patients (62%) had significant renal artery stenosis (Figure 4) and 6 patients (38%) critical stenosis; 13 patients (81%) presented unilateral lesion, one with 2 ipsilateral renal arteries and 3 patients (19%) bilateral (Figure 4), with greater commitment of the right side. 140-149 mm Hg or DBP between 90-99 mm Hg is hypertension stage I and SBP greater than 160 mm Hg or DBP greater than 100 mm Hg is hypertension stage II (10), resistant hypertension refers to patients taking 3 or more antihypertensive drugs of different classes, one of which is a diuretic, without being able to control blood pressure. Hypertension is considered cured when the SBP is reduced below 140 mm Hg and the DBP below 90 mm Hg after angioplasty, without the need to continue with antihypertensive drugs, and controlled hypertension when SBP is reduced below 140 mm Hg and DBP below 90 mm Hg with the decrease in the number of antihypertensive medications. A comparison of serum creatinine values before angioplasty and in the first 24 hrs and at 12 months after angioplasty was performed, considering deterioration of renal function when the serum creatinine increased to a value equal to or greater than 0.5 mg/dl, and improvement of same when a reduction occurs of serum creatinine equal to or greater than 0.5 mg/dl (12). Results Population 16 patients diagnosed with stenosis of more than 50% of the renal artery, aged between 40-89 years; average 69 years, mostly male gender (56%), were included. Fourteen patients (87%) had a diagnosis of hypertension, the average SBP was 160 mm Hg and DBP of 90 mm Hg, of which 8 patients (57%) were diagnosed with resistant hypertension. All patients were admitted in the course of 30 days prior to renal angiography-angioplasty with stenting because of: hypertensive crisis in 5 patients (31%), deteriorated renal failure in 8 patients (50%) and AHT crisis with deteriorated renal failure in 3 patients (19%), one being diagnosed with de novo hypertension in this hospital stay. Risk factors for coronary heart disease such as type 2 diabetes in 6 patients (37%), dyslipidemia in 9 patients (56%), smoking in 4 patients (25%) and Table 2. Risk factors. Characteristics Age 40-89 years, with an average of 69 Gender Female 7 Male 9 Blood Pressure figures Peak systolic blood pressure Average systolic blood pressure Peak diastolic blood pressure Average diastolic blood pressure 200 mm Hg 170 mm Hg 110 mm Hg 95 mm Hg Reason for admission AHT Crisis 5 AHT Crisis with deteriorated renal failure 3 Deteriorated renal failure 8 Arterial Hypertension De novo 1 Suitable Control 5 Poor Control 1 Resistant 8 Diabetes mellitus 6 Dyslipidemia 9 Obesity 2 Smoking 4 Ischemic history 1 (TIA) Creatinine Media high rates Low Maximum 1.83 mg/dl 0.9 mg/dl 4.26 mg/dl Number of antihypertensive drugs 1 2 2 4 3 8 4 1 15

J.M. Vasquez Veloza et al. Rev Chil Radiol 2016; 22(1): 13-19. Figure 4. Bilateral renal arteriography is performed via the right femoral artery. Stenosis of more than 50% in the proximal third of the right renal artery can be seen, so implantation of 6 20 mm metal stent is decided with a satisfactory angiographic result. Critical stenosis is observed in the middle third of the left renal artery, which presents an ulcerated appearance, after pre-dilatation with 4 20 mm balloon catheter implantation of metal prostheses of 5 20 mm diameter is decided, with a satisfactory angiographic result. The angiographic characteristics were of atherosclerotic stenoses, being ostial type lesions in 5 patients (31%) and in 11 patients (69%) non ostial type; 4 patients (36%) with lesions to 1 cm of the ostium and 7 patients (64%) in its proximal third (Table 3). Table 3. Pre-angioplasty vascular characteristics. Variables Left artery 10 Right artery 9 Unilateral 13 Bilateral 3 Assessory 1 Ostium 5 To 1 cm from its source 4 Proximal third 7 Stenosis > 80% 6 50-80% 10 Procedure Of the 20 arterial commitments only 2 balloon pre-dilatations were performed, for critical stenosis that made passage of the catheter difficult. 17 stents (85%) were implanted. The other three stents were not implanted because: in one patient with bilateral commitment, a sufficient selective catheterization for the placement thereof in one side, was not obtained; in the other patient, who presented two ipsilateral renal arteries, access to the upper polar artery is attempted, succeeding on several occasions, but when the time comes to pass the guide catheter to proceed to place the stent it comes out repeatedly, failing to implant safely, so it is removed; in any case the repeated passage of material through the lesion causes an angioplasty effect on it, reducing its stenosis; the last patient only allowed the placement of a stent, although the stenosis was bilateral (such drawbacks were taken into account when collecting data). As a complication, hematoma at the puncture site which completely remitted after local management, was reported in only one patient (Table 4). The average hospital stay was 3 days. Table 4. Post-angioplasty variables. Immediate Immediate complications Inguinal hematoma 1 During the first 24 hrs of the hospital stay Blood pressure figures Peak systolic blood pressure 170 mm Hg Average systolic blood pressure 145 mm Hg Peak diastolic blood pressure 99 mm Hg Average diastolic blood pressure 77 mm Hg Creatinine Average 1.7 mg / dl Minimum 0.9 mg / dl Maximum 3.5 mg / dl Control at 12 months Average blood pressure figures Peak systolic blood pressure Average systolic blood pressure Peak diastolic blood pressure Average diastolic blood pressure Creatinine Average Minimum 145 mm Hg 138 mm Hg 80 mm Hg 70 mm Hg 1.68 mg / dl 1 mg / dl Maximum 3 mg / dl Number of antihypertensive drugs 0 1 1 9 2 4 3 1 Improvement of renal function 3 No change in renal function 10 Deterioration of renal function 3 16

Rev Chil Radiol 2016; 22(1): 13-19. Evolution of blood pressure During the first 24 hours of hospital stay in the 5 hypertensive patients the average SBP was 145 mm Hg with a maximum of 170 mm Hg, and the mean DBP was 77 mm Hg with a maximum of 90 mm Hg, with normal blood pressure values in 6 patients (37%) (Table 4). The patient that was not hypertensive presented no change in their blood pressure readings. Controls at 6 months post-angioplasty were performed with pressure values for SBP with maximum of 150 mm Hg and DBP with maximum of 80 mm Hg. The controls at 12 months post-angioplasty showed pressure values for SBP with average of 138 mm Hg and maximum of 145 mm Hg, and the DBP average was 70 mm Hg with a maximum of 80 mm Hg, these being statistically significant compared to the preangioplasty blood pressure readings (Table 4). The average number of antihypertensive drugs post-angioplasty was one per patient (Table 4). Evolution of renal function In relation to the creatinine in the control at 24 hrs, an average value of 1.7 mg/dl, with a minimum figure of 0.9 and a maximum of 3.5 was found; in the control at 12 months post-angioplasty an average value of 1.68 mg/dl was found; significant improvement in renal function in 3 patients (19%), with improved nonsignificant renal function in 10 patients (62%) and deteriorated renal function in 3 patients (19%) (Table 4). In the patient who was not hypertensive the indication for angioplasty was renal failure secondary to renal artery stenosis, showing improvement in serum creatinine figures at 24 hrs, and at 6 months and 12 months post-angioplasty. Other information 2 deaths occurred in the course of 12-24 months post-angioplasty due to complications of kidney disease (Table 4). No reoperation was performed. Discussion Arterial hypertension is a public health problem that causes multiple organ failure and primary mortality, most often being secondary to the RAS, occurring in up to 5% of hypertensive patients5. RAS is associated with kidney failure, its treatment being in 14% to 20% of patients on dialysis. 6% is associated with end stage nephropathy, a high-risk disease as it has high mortality in the first 3 years after diagnosis (7). Angioplasty with stent is a very controversial procedure, therefore different complementary parameters (angiographic renal blush, fractional flow reserve and doppler resistance rate) are still being evaluated in order to identify the patients who could obtain the greatest clinical benefit, because it does not cure hypertension or renal failure, but helps control both disease processes, either by decreased use of drugs or adequate control of creatinine figures (11). However, current scientific evidence is insufficient to standardize the role of renal angioplasty (12). The latest and largest studies made (ASTRAL and CORAL) concluded that percutaneous intervention with stent placement for handling RAS had no benefits on the control of blood pressure or renal function (basing the latter on the serum creatinine value), but the results are taken as false positives because the tests are biased, either by error in the target population, for the stage of renal failure and for the extent of the same stenosis (in the ASTRAL study: 41% of patients have stenosis <70% of the renal artery, and the CORAL study 55% of patients have stenosis <70% of the renal artery and 50% of the cohort did not present renal failure or did in stage I or II) (13-15). We, in this study that we conducted in 16 patients, 15 hypertensive, all with significant or critical RAS, diagnosed with angiography and treated by angioplasty and stenting, have obtained favourable results for the treatment of hypertension stabilizing their numbers and achieving a better control of same with fewer antihypertensive drugs. Even so, no cure for hypertension was observed. As for serum creatinine numbers, an improvement in statistically nonsignificant renal function was found, providing a stability to that disease. From these results we consider treatment of RAS with angioplasty and stent implantation, as it allows systemic blood pressure improvement and control and stabilizes renal function in patients who have clear indications to undertake this procedure. Conclusion RAS is a disease with great impact in our midst, mainly for causing hypertension and nephropathy. 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