Endovascular Treatment of Renal Artery Stenosis due to Fibromuscular Dysplasia - Is Stent Implantation Underused in this Circumstance?

Fibromuscular dysplasia (FMD) is a nonatherosclerotic and noninflammatory arterial disease that commonly affects the renal and carotid arteries. The primary target in treating patients with renal artery FMD is the control of blood pressure in order to prevent end-organ damage, which can be caused by poorly controlled hypertension. Invasive endovascular treatment should be taken into consideration both when hypertension cannot be controlled with medication. According to current opinion, hypertension attributed to renal artery FMD is often successfully treated solely with percutaneous renal balloon angioplasty (PRBA), with no requirement for stent implantation under most circumstances. However, an FMD recurrence after PRBA occurs frequently in these patients.

INTRODUCTION

Fibromuscular dysplasia (FMD) is a nonatherosclerotic and noninflammatory arterial disease that commonly affects the renal and carotid arteries, but can involve almost every arterial bed.[1] FMD, typically, occurs in premenopausal Caucasian women from 15 to 50 years of age. Its underlying pathogenesis has not yet been fully elucidated.[2]

On angiography, FMD has, typically, been defined as having a “beads-on-a-string” appearance because of the contrast filling of sequential aneurysms along the renal artery, especially the distal two-third of the artery.[3] The primary target in treating patients with renal artery FMD is the control of blood pressure in order to prevent end-organ damage, which can be caused by poorly controlled hypertension.[4] Invasive endovascular treatment should be taken into consideration both when hypertension cannot be controlled with medication and in patients who develop intolerable side effects to increasing doses of antihypertensive drugs.[5] According to current opinion, hypertension attributed to renal artery FMD is often successfully treated solely with percutaneous renal balloon angioplasty (PRBA), with no requirement for stent implantation under most circumstances.

However, FMD recurrence after PRBA occurs frequently in these patients. Therefore, patients require a surveillance program of ultrasound imaging including an assessment of velocity elevations in the region of the previous stenosis so as not to overlook a recurrent renal artery stenosis.

CASE REPORT

A 17-year-old female patient was admitted to our emergency unit due to a sudden onset nosebleed and headache. Her blood pressure was 170/90 mmHg, and there was no blood pressure difference between upper and lower extremities on her physical examination. However, a systolic murmur was heard on the right side of the umbilicus.

The patient had previously undergone PRBA due to FMD involving the right renal artery 2 years earlier. A relapse of renal artery stenosis was suspected. Renal angiography revealed a normal left renal artery and an 80% stenosis showing characteristics of renal artery (FMD) in the mid part of the right renal artery [Figure 1]. Her consecutive blood pressure measurements indicated grade 1 − 2 hypertension, thus, we considered right renal artery stenting due to a relapse of the disease in the same location. The right renal artery was cannulated with a right 7F guiding catheter. Then, a 4 mm × 12 mm RX Herculink Elite Renal Stent System (Abbott Vascular, USA) was implanted successfully at 8 ATMs after a 0.014-inch floppy guide wire was placed distal to the target lesion [Figure 2]. No residual stenosis was observed with the final injection [Figure 3]. Ambulatory blood pressure measurements after the procedure were completely normal.

Figure 1

Stenosis demonstrating characteristics of renal artery fibromuscular dysplasia in the mid-part of the right renal artery

Figure 2

Successful implantation of a 4 mm × 12 mm RX Herculink Elite Renal Stent System (Abbott Vascular, USA) at 8 ATMs

Figure 3

Final enjection of right renal artery with no residual stenosis

DISCUSSION

The primary objective in the management of renal artery FMD is the control of hypertension. Blood pressure can be medically treated in some patients. Further treatment alternatives beyond medical therapy include renal artery revascularization, which can be achieved surgically or percutaneously.

Renal artery FMD is a curable cause of hypertension and typically involves the mid and distal parts of the renal arteries. Balloon dilatation systems with different sizes offer reliable and highly effective treatment options for a technically difficult stenosis. Theoretically, stenting for renal artery FMD is exclusively reserved for fixing complications from a PRBA, such as a dissection or rupture that cannot otherwise be treated with a balloon, or if the pressure gradient is not able to be decreased with PRBA alone.[6] A recurrence after PRBA occurs frequently and these patients require surveillance programs that result in an unwarranted economic burden.

In 2008, Davies et al. conducted an endovascular revascularization study in 29 women with renal artery FMD and reported that the restenosis rate was 28% at 5 years after successful PRBA.[7] Mann and Toss stated that renal artery stenting should be performed in patients who suffer from hemodynamically significant renal artery stenosis and who do not respond to medical therapy alone.[8]

Considering all these data, we believe that renal artery stenting should be the preferred treatment method for symptomatic renal artery FMD to avoid repeated endovascular procedures.

CONCLUSION

Renal artery stenosis triggered by renal artery FMD should be kept in mind as a cause of secondary hypertension, particularly in young females. We suggest that renal artery stenting should be the first-line treatment in patients with symptomatic renal artery FMD due to the high recurrence rates after PRBA alone and the excessive follow-up costs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.