Etiology And Interventional Therapy Of Renal Artery Stenosis

Part ⅠBackground and Objective:In the Western population, atherosclerosis is reported as the most common cause of renal artery stenosis (RAS),followed by fibromuscular dysplasia (FMD). However, systematic investigation with large sample size of the distribution of etiologies of RAS is scant in both Western countries and China. The objective of the present study was to analyze a relatively large study population with RAS in China to understand such distribution pattern.Methods:We retrospectively analyzed the etiology of RAS in consecutive 2047 inpatients diagnosed with RAS for hypertension. Patients presented for work-up at our institute between March,1999 and June,2014. All of the patients suffered from Grade≥2 hypertension. RAS was diagnosed if the diameter reduction in the renal artery was≥50%. 1564(76.4%) patients were diagnosed by angiography, the remaining 483 (23.6%) of patients were diagnosed by computed tomography angiogram. The etiologic diagnosis of RAS was confirmed by characteristic clinical and radiological findings.Results:The number of patients with atherosclerosis was 1668 (81.5%),259 (12.7%) with Takayasu’s arteritis,86 (4.2%) with FMD,34 (1.6%) with other causes. There was an obvious increase with age in the proportion of atherosclerotic RAS (P<0.001). In patients aged≤40 years (n=319) the predominant etiology of RAS was Takayasu’s arteritis (60.5%), followed by FMD (24.8%). In patients aged>40 years (n=1728) the major cause of RAS was atherosclerosis (94.7%), followed by Takayasu’s arteritis (3.8%). The proportion of Takayasu’s arteritis and FMD in female patients was significantly higher than that in male patients (P<0.001). In female patients aged≤40 years (n=215), the top three etiologies of RAS were Takayasu’s arteritis (68.4%), FMD (27.9%) and atherosclerosis (1.4%). In male patients aged≤40 years (n=104), the order of the etiology of RAS was Takayasu’s arteritis (44.2%), atherosclerosis (26.9%) and FMD (18.3%). During the period between 1999 and 2014 the predominant etiology of RAS was atherosclerosis, followed by Takayasu’s arteritis. There was a gradual increase in the proportion of atherosclerotic RAS during the past 15-year period.Conclusions:The present analysis showed atherosclerosis, Takayasu’s arteritis and FMD were sequentially the top three causes of RAS in our center. Age and gender had a significant effect on the distribution of etiologies of RAS.Part ⅡBackground and Objective:Percutaneous balloon angioplasty (PTA) is usually recommended as a first-line therapy for renovascular hypertension caused by Takayasu’s arteritis. Selective stent placement is considered as an alternative therapy for suboptimal outcomes or failure after PTA. So far, the long-term clinical outcomes of selective stent placement in patients with renal artery stenosis caused by Takayasu’s arteritis (RASTA) need to be clarified. The purpose of the present study was to investigate the long-term clinical outcomes of selective stenting versus PTA in patients with RASTA.Methods:We retrospectively analyzed the data of 152 consecutive patients with RASTA undergoing endovascular treatment at our institute between 2005 and 2012. At baseline the information on social, demographic and clinical factors was collected. Patients were followed up at 1,6,12,18 and 24 months after the procedure. Erythrocyte sedimentation rate, C-reactive protein, serum creatinine, renal artery color duplex scanning and blood pressures were measured at every visit. The types and dose of drugs and the primary composite clinical events were also recorded.Results:At two-year follow-up, the proportion of hypertension cure, improvement, and failure was 27.4%,63.4% and 12.3% in the PTA group (n=93),22.4%,62.1% and 15.5% in the stent group (n=59), respectively, P=0.79. Estimated glomerular filtration rate increased slightly, and there was no significant difference between the two groups. Primary patency rate was 90.1% in renal arteries (125 lesions) treated with PTA,75.6% in renal arteries (64 lesions) treated with stent, P=0.008. Cox regression analysis suggested that stent placement (risk ratio,3.41; 95%CI:1.575-7.370; P=0.002), residual stenosis rate (risk ratio,1.04;95%CI:1.013-1.077;P=0.006), female gender (risk ratio, 2.84; 95%CI:1.28-6.29; P=0.01) and active disease in need of steroid and/or immunosuppressant agents (risk ratio,3.32;95%CI:1.388-7.928; P=0.007) were significantly associated with the restenosis. In patients with restenosis, renal artery occlusion occurred more frequently in the stent group (8/15,53.3%), compared with that in the PTA group (1/12,8.3%), P=0.019. Reintervention was more common in the stent group (13/63,20.6%), including nephrectomy in 3 patients, than that in the PTA group (8/125,6.4%), P=0.003. In the stent group, progressive renal insufficiency occurred in 2 patients (3.4%).Conclusions:Though. PTA alone and selective stenting had no significant difference in terms of the effect on blood pressure, stenting resulted in inferior 2-year primary patency rate, higher occlusion rate and higher reintervention rate. It should be seriously considered before stenting was undergone in patients with RASTA,. particularly in patients with high risk for restenosis.Part ⅢBackground and Objective:Although contrast medium (CM) nephrotoxicity is often neglected in clinical practice, contrast-induced nephropathy (CIN) was reported to range between 11% and 50% in the patients with multiple risk factors, and was the third leading cause of hospital-acquired acute renal failure, resulting in increased patient morbidity and mortality. It is generally thought that renal micro-embolization, direct injection of CM into the renal artery and repeated transient blockage of blood flow during renal artery revascularization (RAI) may sensitize patients to the toxic effect of CM. However, it is unclear whether CM-induced renal damage is greater in patients who underwent RAI. Therefore, the purpose of this prospective cohort study was to compare the nephrotoxic effect of iodixanol in elderly patients who underwent RAI or other peripheral vascular intervention (OPI).Methods:In the prospective study 354 consecutive patients (>60 years old) received iodixanol during RAI (n=150) or OPI (n=204). Serum creatinine (SCr) was measured at baseline,24h,48h,72h and 1 month after intervention.Results:Within 72h after intervention, the adjusted mean of the peak SCr increase was 11.22 umol/L (95%CI:9.21-13.24) in the RAI group and 12.40 umol/L (95%CI: 10.7-14.09) in the OPI group. The difference in the peak SCr increase was -1.17 umol/L (95%CI:-3.94-1.60, P=0.41). The adjusted mean of the peak decrease in eGFR was 10.94 mL/min/1.73 m2 (95%CI:9.41,12.43) in the RAI group and 10.31 mL/min/1.73 m2 (95%CI:9.02,11.61) in the OPI group. The difference in the peak eGFR decrease was 0.63 mL/min/1.73 m2 (95%CI:-1.48,2.74, P=0.56). Within 72h after the procedure CIN occurred in 26 patients (17.3%) of the RAI group and in 27 patients (13.2%) of the OPI group (P=0.29). An absolute increase of≥ 44.2 μmol/L (0.5mg/dL) in SCr was observed in 5 (3.3%) patients of the RAI group and in 8 (3.9%) patients of the OPI group (P=0.77). Patients who underwent RAI had no increased risk for CIN compared to patients who underwent OPI (adjusted OR=1.108,95%CI:0.540-2.273, P=0.78). At 30 days after the procedure, a relative increase of≥25% or an absolute increase of ≥44.2 μmol/L (0.5 mg/dL) in SCr still existed in 15 (4.2%) patients (6 for the RAI group,9 for the OPI group, P=0.85)Conclusions:The nephrotoxic effect of iodixanol in elderly patients who underwent RAI or OPI was comparable.Part ⅣBackground and Objective:Some studies showed that renal artery stent cannot reverse kidney damage, suggesting that increased renal blood flow cannot compensate for the unfavorable effects of hypertension and atherosclerosis on renal function. An appropriate antihypertensive treatment may be an important approach to improve the efficacy of renal artery stents. The purpose of this study was to investigate the nephroprotective effect of taking lercanidipine regularly in patients undergoing renal artery intervention.Methods:A prospective, single-center study was conducted and the patients with atherosclerotic renal artery stenosis undergoing renal artery intervention aged 30-75 year were consecutively enrolled between September,2011 and October,2012. Lercanidipine was regularly taken after the intervention. All patients were invited to present themselves at our institute at 3 and 6 months after the intervention. Serum creatinine, clinical blood pressure (BP),24-hour ambulatory BP, brachial-ankle pulse wave velocity, fasting blood glucose, lipids and 24-hour urine protein were measured. Adverse events were recorded.Results:At 3 months after the intervention either estimated glomerular filtration rate or 24-hour urine protein was not statistically different compared with the baseline. At 6 months after the intervention 24-hour urine protein decreased significantly [0.02 (IQR.0.01-0.1) VS 0.03 (IQR,0.01-0.28)g, P=0.04] and estimated glomerular filtration rate increased significantly [(78.0±23.1) VS (71.3±21.4) m 1/min/1.73 m 2, P=0.02]. BP control was more effective at 3 and 6 months after intervention than during the preoperative period (baseline). At 3 months, the number of different antihypertensive drugs administered to patients had significantly decreased [(1.81±0.82) VS (2.31±0.76),P=0.001], as well as clinical and 24 hour systolic and diastolic BP [clinical systolic BP:(143.1±15.7) VS (158.4±17.9) mmHg, P<0.001; clinical diastolic BP: (77.4±11.0)VS (86.4±12.2) mmHg, P<0.001;24 hour systolic BP:(133.6±15.9) VS (143.9±20.2) mmHg, P=0.001;24 hour diastolic BP:(71.8±9.9)VS (80.3±11.0) mmHg, P<0.001]. At 6months, the number of antihypertensive drugs significantly decreased [(1.67±0.93) VS (2.31±0.76), P<0.001],clinical systolic BP [(136.1±15.4) VS (158.4±17.9) mmHg, P<0.001]:diastolic BP[(73.9±9.3)VS (86.4±12.2) mmHg, P<0.001] and 24 hour average systolic BP[(122.4±23.2) VS (143.9±20.2) mmHg, P <0.001], and diastolic BP [(69.0±10.0) VS (80.3±11.0)mmHg, P<0.001] significantly decreased. Brachial-ankle pulse wave velocity was significantly decreased at 3 months and 6 months after intervention. Lercanidipine did not exert negative effects on glucose or lipids homeostasis. At the end of follow-up, death, dialysis, myocardial infarction or stroke occurred in none of the patients. Mild lower extremity edema occurred in only one patient. No other side effects occurred.Conclusions:The study showed that taking lercanidipine regularly may improve renal function in patients with atherosclerotic renal artery stenosis undergoing renal artery intervention.