Abstract
The benefit from renal artery stent implantation to treat atherosclerotic renal artery stenosis (ARAS) is not well understood in hemodialysis patients. We sought to evaluate the effects of renal artery stenting on hypertension of hemodialysis patients. Renal artery stent implantation was successfully performed on eight hypertensive hemodialysis patients with ARAS (mean ± SD, 66 ± 10 years; men 6, women 2). Blood pressure was measured by automated oscillometric recordings just before hemodialysis. Mean values of the blood pressure, measured 12 times a month, were used for blood pressure analysis. Values of systolic blood pressure decreased at 6 months after renal artery stent implantation (162.6 ± 29.7 to 121.1 ± 23.3 mm Hg, p = 0.0015). Values of diastolic blood pressure also decreased from 77.6 ± 13.6 to 65.6 ± 7.2 mm Hg (p = 0.02). Renal artery stent implantation for ARAS had a beneficial effect on hypertension in hemodialysis patients.
Keywords: atherosclerotic renal artery stenosis, renal artery stent implantation, hypertension, hemodialysis, blood pressure
Atherosclerotic renal artery stenosis (ARAS) is strongly associated with accelerated hypertension and progressive renal dysfunction.1 The clinical benefit of percutaneous renal artery intervention with stent implantation for ARAS remains controversial.2 3 4 5 6 7 However, there is a potential benefit of renal artery stenting in hemodynamically significant renal artery stenosis on hypertension in certain settings.2 5 6 Translesional pressure gradients and renal frame count have predicted blood pressure response after renal artery stenting.8 9
Among patients who were receiving dialysis, those with renovascular disease (ARAS) have a low survival rate.10 There were few studies to evaluate the impact of renal artery stenting on blood pressure lowering in hemodialysis patients with ARAS. The purpose of our study is to evaluate the effect of renal artery stenting on hypertension in hemodialysis patients with ARAS.
Methods
Study Population and Study Protocol
The study included eight hemodialysis patients with hypertension who fulfilled the following inclusion criteria: (1) persistent arterial hypertension (systolic blood pressure > 140 mm Hg and/or diastolic blood pressure > 90 mm Hg) as measured by cuff manometry at the outpatient clinic despite two or more antihypertensive medications, (2) presence of ARAS of > 50% diameter stenosis by quantitative angiographic estimate on distal abdominal aortogram, and (3) renal artery stenting performed for treating uncontrolled hypertension.
Renal Artery Stenting
All the patients provided informed consent for renal artery intervention. All patients received 100 mg aspirin orally once daily and 75 mg clopidogrel orally once daily for at least 4 days before the procedure. Heparin was used as the procedural anticoagulant agent. Percutaneous renal artery intervention was performed in a standard fashion. A renal guiding catheter was inserted via either the femoral or brachial artery and was advanced into the ostium of the stenosed renal artery. A control angiogram was performed for quantitative angiography. Reference diameter, minimal luminal diameter, and percent diameter stenosis were determined with the guiding catheter as a scaling device. A 0.014-in guide wire was advanced across the stenosis site. Stenting of the renal artery stenosis was performed following balloon dilatation. If necessary, post–balloon dilatation was performed to obtain an acceptable result of residual diameter stenosis < 10% by quantitative angiography. In bilateral significant ARAS cases, the significant ARAS on the other side was treated within a month following percutaneous renal intervention of the significant ARAS on one side.
Blood Pressure Measurements
Blood pressure was measured by automated oscillometric recordings just before hemodialysis. All study patients received hemodialysis three times a week. Mean values of the blood pressure measured 12 times a month were used for blood pressure analysis. Mean values of blood pressure for a month were assessed at preintervention and 6 months after final renal stenting.
Statistics
Data were expressed as mean ± standard deviation. Continuous variables were compared using paired student t-test. All statistical analyses were performed using JMP version 9 (SAS Inc., Chicago, IL). Statistical significance was defined as p < 0.05 (two-tailed).
Results
Baseline clinical characteristics are shown in Table 1. Angiographic data are listed in Table 2. Renal artery intervention procedural success was obtained in all cases. At 6 month follow-up, mean values obtained in blood pressure measurements for a month were significantly lower for both systolic blood pressure and diastolic blood pressure compared with the preprocedural values ( Table 3). The mean decrease in systolic blood pressure and diastolic blood pressure was 41.5 ± 23.3 mm Hg and 12.0 ± 11.3 mm Hg, respectively. A representative case is shown in Fig. 1. The numbers of antihypertensive medications were not changed in any case. All the study patients had still received hemodialysis at 6 months after renal artery stenting.
Table 1. Clinical baseline characteristics.
| Characteristics | Value |
|---|---|
| Total patients, N | 8 |
| Men | 6 |
| Women | 2 |
| Age (y) | 66 ± 10a |
| Coronary artery disease (n) | 8 |
| History of heart failure (n) | 2 |
| Diabetes mellitus (n) | 5 |
| Hypertension (n) | 8 |
| Dyslipidemia (n) | 1 |
| Smoking (current and former) (n) | 4 |
| Period of hemodialysis (y) | 6 ± 2a |
| Serum creatinine (mg/dL) | 8.0 ± 3.4a |
Values are given as mean ± SD.
Table 2. Angiographic and procedural characteristics.
| Characteristics | Value |
|---|---|
| Target vessels (n) | 10 |
| Unilateral/bilateral (n) | 6/2 |
| Prestent DS (%) | 63.4 ± 9.3a |
| Prestent MLD (mm) | 1.75 ± 0.47a |
| Poststent DS (%) | 12.1 ± 5.0a |
| Poststent MLD (mm) | 4.17 ± 0.53a |
| Procedural success (%) | 100 |
Abbreviations: DS, diameter stenosis; MLD, minimal lumen diameter.
Values are given as mean ± SD.
Table 3. Blood pressure measurements.
| Prestent | After 6 mo | p-Value | |
|---|---|---|---|
| Systolic BP (mm Hg) | 162.6 ± 29.7a | 121.1 ± 23.3a | 0.0015 |
| Diastolic BP (mm Hg) | 77.6 ± 13.6a | 65.6 ± 7.2a | 0.02 |
Abbreviation: BP, blood pressure.
Values are given as mean ± SD.
Fig. 1.
Stenosis of (A) right renal artery and (B) left renal artery. Palmaz Genesis stent implanted (C) in the right renal artery and (D) in the left renal artery. Values of blood pressure decreased from 160/81 mm Hg before renal artery stenting to 139/70 mm Hg at 6 months after stenting.
Discussion
In this study, we demonstrated that in hemodialysis patients with significant ARAS, renal artery stenting improved blood pressure control at the follow-up period of 6 months. Although, there are several reports indicating that renal artery stenting in hemodialysis patients with ARAS improved renal dysfunction,11 there were few studies to evaluate the impact of renal artery stenting on blood pressure lowering in hemodialysis patients with ARAS.
It has been noted that the circulating renin–angiotensin–aldosterone system is markedly active in chronic hemodialysis patients.12 Based on this concept, medications aimed at blocking the renin–angiotensin–aldosterone system were used for treating hypertension in hemodialysis patients.13 However, the hemodialysis population has shown a high prevalence of hypertension which is resistant to antihypertensive drugs.14 Hemodialysis patients with uncontrolled hypertension had a poor prognosis.14 Further intervention was warranted in these hemodialysis patients.
It has been speculated that hemodialysis patients with significant ARAS have a more active renin–angiotensin–aldosterone system than those without ARAS. In hypertensive hemodialysis patients with ARAS, improvement of renal artery blood flow with renal artery stenting may lead to suppress an increased renin–angiotensin–aldosterone system and control drug-resistant hypertension. It was reported that the prevalence rate of ARAS was 83 out of 683 in hemodialysis patients (12.2%).10 Assessment of ARAS is important in hemodialysis patients. Furthermore, percutaneous renal intervention with stenting may be useful to control oral drug-resistant hypertension in hemodialysis patients with significant ARAS.
There were several limitations of our study. The number of the study patients was very small. Serum values of renin, angiotensin, and aldosterone were not measured in our study. A condition of increased renin–angiotensin–aldosterone system was not possible to be evaluated in our patients. Due to a small number of the study patients, evaluation of prognostic factors for blood pressure lowering by renal artery stenting, such as renal artery pressure gradient and frame count8 9 was not performed. This study follow-up was performed at only 6 months after renal artery stenting. Results of restenosis after renal artery stenting were not indicated in our study. Long-term results of arterial blood pressure after renal artery stenting were not evaluated. Further studies with large numbers of patients and a long-term follow-up period are needed to evaluate the usefulness of renal artery stenting in hypertensive hemodialysis patients with ARAS.
Conclusions
Percutaneous renal artery intervention with stenting improved arterial blood pressure after 6 months in hypertensive hemodialysis patients with significant ARAS.
Funding
The author(s) received no financial support for the research and/or authorship of this article.
Footnotes
Conflict of Interest The author(s) declare no potential conflict of interests with respect to the authorship and/or publication of this article.
References
- 1.Safian R D, Textor S C. Renal-artery stenosis. N Engl J Med. 2001;344(6):431–442. doi: 10.1056/NEJM200102083440607. [DOI] [PubMed] [Google Scholar]
- 2.Dorros G, Jaff M, Mathiak L. et al. Four-year follow-up of Palmaz-Schatz stent revascularization as treatment for atherosclerotic renal artery stenosis. Circulation. 1998;98(7):642–647. doi: 10.1161/01.cir.98.7.642. [DOI] [PubMed] [Google Scholar]
- 3.Bax L Woittiez A JJ Kouwenberg H J et al. Stent placement in patients with atherosclerotic renal artery stenosis and impaired renal function: a randomized trial Ann Intern Med 200915012840–848., W150-1 [DOI] [PubMed] [Google Scholar]
- 4.Wheatley K, Ives N, Gray R. et al. Revascularization versus medical therapy for renal-artery stenosis. N Engl J Med. 2009;361(20):1953–1962. doi: 10.1056/NEJMoa0905368. [DOI] [PubMed] [Google Scholar]
- 5.Rocha-Singh K J, Novack V, Pencina M. et al. Objective performance goals of safety and blood pressure efficacy for clinical trials of renal artery bare metal stents in hypertensive patients with atherosclerotic renal artery stenosis. Catheter Cardiovasc Interv. 2011;78(5):779–789. doi: 10.1002/ccd.23055. [DOI] [PubMed] [Google Scholar]
- 6.Jaff M R, Bates M, Sullivan T. et al. Significant reduction in systolic blood pressure following renal artery stenting in patients with uncontrolled hypertension: results from the HERCULES trial. Catheter Cardiovasc Interv. 2012;80(3):343–350. doi: 10.1002/ccd.24449. [DOI] [PubMed] [Google Scholar]
- 7.Miyashita Y, Ikeda U, Soga Y, Yokoi H, Suzuki K, Inoue N. Results of the retrospective analysis of renal artery stenting for the salvage of renal function study. Angiology. 2013 doi: 10.1177/0003319713501069. [DOI] [PubMed] [Google Scholar]
- 8.Mangiacapra F, Trana C, Sarno G. et al. Translesional pressure gradients to predict blood pressure response after renal artery stenting in patients with renovascular hypertension. Circ Cardiovasc Interv. 2010;3(6):537–542. doi: 10.1161/CIRCINTERVENTIONS.110.957704. [DOI] [PubMed] [Google Scholar]
- 9.Mahmud E, Smith T WR, Palakodeti V. et al. Renal frame count and renal blush grade: quantitative measures that predict the success of renal stenting in hypertensive patients with renal artery stenosis. JACC Cardiovasc Interv. 2008;1(3):286–292. doi: 10.1016/j.jcin.2008.03.012. [DOI] [PubMed] [Google Scholar]
- 10.Mailloux L U, Napolitano B, Bellucci A G, Vernace M, Wilkes B M, Mossey R T. Renal vascular disease causing end-stage renal disease, incidence, clinical correlates, and outcomes: a 20-year clinical experience. Am J Kidney Dis. 1994;24(4):622–629. doi: 10.1016/s0272-6386(12)80223-x. [DOI] [PubMed] [Google Scholar]
- 11.Thatipelli M, Misra S, Johnson C M. et al. Renal artery stent placement for restoration of renal function in hemodialysis recipients with renal artery stenosis. J Vasc Interv Radiol. 2008;19(11):1563–1568. doi: 10.1016/j.jvir.2008.08.016. [DOI] [PubMed] [Google Scholar]
- 12.Blankestijn P J, Ligtenberg G. Volume-independent mechanisms of hypertension in hemodialysis patients: clinical implications. Semin Dial. 2004;17(4):265–269. doi: 10.1111/j.0894-0959.2004.17324.x. [DOI] [PubMed] [Google Scholar]
- 13.Morishita Y, Kusano E. The blockade of renin-angiotensin-aldosterone system in hemodialysis patients to control hypertension and prevent cardiovascular disease: optimal pharmacotherapy. Cardiovasc Hematol Agents Med Chem. 2011;9(4):241–246. doi: 10.2174/187152511798120903. [DOI] [PubMed] [Google Scholar]
- 14.Grekas D, Bamichas G, Bacharaki D, Goutzaridis N, Kasimatis E, Tourkantonis A. Hypertension in chronic hemodialysis patients: current view on pathophysiology and treatment. Clin Nephrol. 2000;53(3):164–168. [PubMed] [Google Scholar]