Percutaneous transluminal angioplasty in the treatment of renovascular hypertension : sequential prospective study

Objective: to evaluate the use of percutaneous transluminal renal angioplasty (PTRA) in the treatment of renal vascular hypertension. Design: sequential prospective PTRA treatment of severe arterial hypertension, screening by the captopril test, confirmed by renal arteriography, and the result evaluated by post-PTRA arteriography, blood pressure measurement and renal function. Site: Vascular Surgery, angioradiology sector, and Nephrology outpatients department of the Federal University of Sao Paulo Paulista School of Medicine, Sao Paulo, Brazil, a tertiary health-care institution. Participants: PTRA was employed on 32 patients screened by clinical examination, captopril test and renal arteriography. Evaluation: PTRA results were evaluated by the criteria of the Cooperative Study of Renovascular Hypertension. Results: after PTRA the completion arteriography showed no renal stenosis in 24 patients (75%), residual stenosis (20-50%) in 3 (9.4%) and no change in 5 (15.6%). The blood pressure results were: 3 patients (9.4%) were cured, 24 (75%) improved and 5 (15.6%) were unchanged. We observed normal renal function before and after PTRA in 25 patients (78%); altered preand improved post-PTRA in 2 (6.3%); post-PTRA remained unaltered in 2 (6.3%); and altered preand worsened postPTRA in 3 (9.4%). Recurrence of stenosis occurred in one patient after 8 months. Conclusions: PTRA is a convenient procedure, relatively safe and an effective complementary method of medical therapy for controlling renovascular hypertension.

Address for correspondence: Fausto Miranda Jr. Rua Estela, 515 -bloco G -cj 81 Sao Paulo/SP -Brazil-CEP  Acquired experience has reduced the complications rate and primary success has reached nearly 900/0(2-13) with good results above 70% in longer follow-ups (14)(15)(16)(17)(18)(19)(20).The treatment decision is taken by a multidisciplinary team, PTRA being the first choice except in cases of anticipated technical difficulties, treating one renal lesion at time in cases of bilateral lesion.PTRA has a low incidence of technical failure and renal loss, being the preferred route for inguinal.catheterism.Balloon-catheter insufflation at the stenosis site breaks the intimal layer, the atherosclerotic plaque and the medial layer, dilating the renal artery (21,22).Complications have been reduced and primary successes increased with greater experience and technological advance, using digital subtraction angiography, reduced quantities of injected contrast, adequate hydration and better materials (23).Good results have been observed in children (1~J), transplanted kidneys (24\ segmental renal branches (25), ostial lesions (26,27) and even in short segmental obstructions (28).PTRA is considered a long-term effective treatment for preventing renal function impairment and controlling blood pressure (19,24,25).
The good results observed in the medical literature have led us to use this procedure and the aim of this article is to summarize our experience.with PTRA in the treatment of renovascular hypertension.

PATIENTS AND METHODS
Out of a total of 2,554 angiograms performed during a five year period, 137 patients (5.6%) with arterial hypertension underwent screening renal arteriography.Percutaneous transluminal renal angioplasty (PTRA) was performed on 32 patients with renovascular hypertension The technique used for renal angioplasty did not differ from the classic techniques reported in the literature (29)(30)(31)(32).Acetylsalicylic acid 500 mg/day was prescribed for six months after the procedure.
The results were evaluated in accordance with the criteria of the Cooperative Study of Renovascular Hypertension (33): 1 -The technical results before and after PTRA were quantified as: without stenosis, having residual stenosis (20-50%), and unchanged.2 -The blood pressure results were classified as cured (without antihypertensive drugs), improved (controlled with decreased doses of antihypertensive drugs), and unchanged.3 -the renal function results before and after PTRA were classified by the creatinine dosage needed.4 -the complications of the procedure and recurrence of the hypertension.

DISCUSSION
Recurrence of stenosis occurred in one patient after 8 months, which was treated with another successful PTRA after the termination of this work.

Table 3
Complications in 10 out of 32 patients treated with percutaneous transluminal angioplasty Renal function impairment and the progression of renovascular disease has been associated with the clinical treatment of renovascular hypertension.
PTRA and surgical treatment result in better control of arterial hypertension with lesser occurrence of cardiovascular events and mortality, preserving renal function (lR,33,34).
The use of PTRA in the treatment of renovascular hypertension has lower operative risk and the results are comparable to surgical treatment (R,IR).
To evaluate the results of PTRA the criteria of the Cooperative Study of Renovascular Hypertension were used (33).The technical results of PTRA depend upon the stenosis characteristics (29), chiefly the etiology, our best results being the treatment of fibromuscular hyperplasia which was similar to other authors (14,15,19,25,31,(35)(36)(37)(38).These good results, ranging from 89 to 100%, may be attributed to younger age groups and lesser effects of hypertension on contralateral kidney and systemic vessels (21).Recently, with a minor procedural risk, a cure rate of less than 300/0 has been obtained in the atherosclerotic group, which should be compared with rates greater than 50% in the fibromuscular dysplasia group (18).No significant difference has been found between ostial and non-ostial PTRA treatment results of renal lesions (20,26,27).These findings are different from some works relating ostial dilating difficulties compared with non-ostial lesions (15,29,39), because ostial plaque is generally an extension of aortic plaque.
The PTRA cure rate is low, ranging from 60/0(40) to 25%(4,15), and the best results have been obtained in fibromuscular dysplasia (25).In our experience the cure rate was 9.4%.The hypertension control with decreased doses of medication was a real benefit, as obtained in 750/0 of our patients treated with PTRA and in accordance with other authors (21) (table 4).
The PTRA complication rate ranged from 7.2%(34) to 46.2%(16\ with local complications being the most frequent.We observed PTRA complications in 10 patients (table 3).However, the lack of comparability between patients in different series and the problem of definition of a "complication" leaves the discussion of this issue outside of the scope of this paper.
In these cases surgical treatment or a new PTRA should be performed.In one of our patients, changing the femoral catheterization method  to the axillar route made the catheteriiation and dilation of the renal artery successful.
In the literature, a recurrence rate of 5 to 8% has been reported (9,15,20,41).Generally, most recurrences take place within the first year (l7).Our patient with recurrence of renal stenosis 8 months after PTRA was successfully submitted to redilation after the end of this study.The use of PTRA and "stents" has been recommended for diminishing the recurrence of renal stenosis (42,43), although these devices are at present expensive and are not available in the public hospital where we work.
In conclusion, PTRA is a relatively safe and convenient procedure and an effective complementary method of medical therapy for controlling hypertension.

Table 2 Etiology
1 -The technical results of PTRA were shown by the completion arteriography: renal artery without stenosis in 24 patients (75%), residual stenosis in 3 (9.4%),and unchanged in 5 (15.6%). 2 -The blood pressure results ranged from one month to five years (mean period of 16 months),