The natural history of atherosclerotic and fibrous renal artery disease

Response of blood pressure after percutaneous transluminal renal artery angioplasty and stenting

AIM: To evaluate the short and intermediate term outcome of percutaneous transluminal renal artery angioplasty (PTRA) and stenting particularly on blood pressure (BP) control and renal function and to evaluate predictors of poor BP response after successful PTRA and stenting.

METHODS: We conducted a prospective analysis of all patients who underwent PTRA and stenting in our institute between August 2010 to September 2012. A total number of 86 patients were underwent PTRA and renal stenting. Selective angiography was done to confirm at least 70% angiographic stenosis. The predilatation done except few cases with critical stenosis, direct stenting was done in the rest of cases. All patients received aspirin 325 mg orally, and clopidogrel 300 mg orally within 24 h before the procedure. Heparin was used as the procedural anticoagulant agent. Optimal results with TIMI-III flow obtained in all cases. Following stent placement, aspirin 150 mg orally once daily was continued for a minimum of 12 mo and clopidogrel 75 mg orally once daily for at least 4 wk. The clinical, radiological, electrocardiography, echocardiography and treatment data of all patients were recorded. The BP measurement, serum creatinine and glomerular filtration rate (GFR) were recorded before the procedure and 1 and 6 mo after PTRA.

RESULTS: A total of 86 patients were included in the study. The mean age of study population was 55.87 ± 11.85 years old and 67 (77.9%) of patients were male. There was a significant reduction in both systolic and diastolic BP at 1 mo after the procedure: 170.15 ± 20.10 mmHg vs 146.60 ± 17.32 mmHg and 98.38 ± 10.55 mmHg vs 89.88 ± 9.22 mmHg respectively (P = 0.0000). The reduction in BP was constant throughout the follow-up period and was evident 6 mo after the procedure: 144.23 ± 18.19 and 88.26 ± 9.79 mmHg respectively (P = 0.0000). However, no improvement in renal function was observed at any time during the follow-up period. After multivariate analysis, we found male sex, low GFR (< 60 mL/min) and higher baseline mean BP as a poor predictors of successful outcome on BP response after PTRA and stenting.

CONCLUSION: The PTRA and stenting can be considered as an effective therapeutic intervention for improving BP control with minimal effect on renal function. The male sex, higher baseline BP and low GFR are associated with poor BP response after successful PTRA and stenting.

Renovascular hypertension

Renovascular hypertension is the most common cause of secondary hypertension. Interest in identifying patients with renal artery stenosis has been stimulated recently by advances in three areas. First, is the realization that not only can renal artery stenosis cause renovascular hypertension, but it can also lead to progressive renal failure (ischemic nephropathy) caused by progression of disease, usually atherosclerotic in nature. Second, advances in percutaneous transluminal renal angioplasty and, especially, the recent use of renal stents has led to a less invasive management of these patients as compared with traditional renal revascularization. Finally, the development of newer less invasive diagnostic techniques, both for the identification of patients with renal artery stenosis and to follow patients with known renal artery stenosis, has simplified the diagnostic aspect of the disease.

Defining the role of renal angiography in the diagnosis of renal artery disease

The current goal of angiography in the diagnosis of renal artery disease is poorly defined, probably because of the diversity of patients presenting for management. The current application of angiography is better understood when put into perspective with the patient population that we are trying to screen. There are two distinct patient populations with renovascular disease: those with uncontrolled hypertension and those with azotemia or risk of progression to end-stage renal disease. The role of angiography in these two patient populations is quite different. In patients with hypertensive renovascular disease, angiography should be applied rather late and should be preceded by other noninvasive testing to screen patients from those with essential hypertension, since the prevalence of this disease is low and the cost implications of applying angiography primarily are immense. The two promising tests in this setting are captropril renography and duplex ultrasound scanning. In contradistinction, patients with azotemic renovascular disease, suffering from bilateral renal artery stenoses, or suffering from stenosis of the renal artery in a solitary kidney may be better studied by early application of renal angiography, especially those at risk of progression and for whom intervention is indicated.