Teaching Case

A young twenty-one-year-old female patient presented with complaints of headache and palpitation for four years which has now progressed for the past two weeks. The patient had no complaints of facial puffiness, pedal oedema or reduced urine output.

The patient underwent a thorough clinical evaluation and blood evaluation and subsequent ultrasound abdomen and renal Doppler. Renal Doppler scan showed increased peak systolic velocity in the right kidney.
Renogram showed excretory function of 42% on the right and 58% on the left. On viewing CT angiography and illustrating further history of previous interventions in the past, the patient was taken up for conventional angiography.
Right renal artery showed a string of bead sign on the conventional angiographic run. Left renal artery was normal. A percutaneous transluminal angioplasty was performed with repeat contrast run showing disruption of stenosis with good flow across the right renal artery.

Background:
Fibromuscular dysplasia (FMD) is a non-inflammatory condition which affects the medium and small size vessels. The exact pathophysiology of the disease is still not well understood. Patients with FMD usually are young presenting with hypertension secondary to renal artery stenosis. Patients are also noted to come with complaints of headaches, tinnitus, dizziness and neck pain. The condition is highly prevalent in the female population [1]. Imaging plays a crucial role in the early diagnosis and treatment of the disease. Renal arteries are the most common vessel to be involved, other vessels commonly involved include vertebral artery and carotid artery.
Clinical Perspective:
Based on the arterial layer involved it has been classified as medial type, intimal type and subadventitial type [2]. However, based on angiographic findings, it is now classified as a) multifocal, b) unifocal, c) tubular and d) mixed type [3].
Imaging:
Doppler ultrasound shows accelerated flow in renal arteries with asymmetry in size based on the severity of stenosis. CT angiography and MR angiography have high specificity (84% and 92% respectively) and low sensitivity (62% and 64% respectively) [4]. Various complications associated with the condition include dissection, distal embolisation, aneurysm and av fistula. 33% of patients have bilateral renal arteries involvement requiring a meticulous evaluation.
Outcome:
Percutaneous transluminal angioplasty (PTA) is the mainstay of treatment, and the procedure has an excellent technical success and outcome. Indications include resistant hypertension, renal impairment, and intolerance to hypertensive medications [5].The main aim of the procedure is to disrupt the stenosis to relieve the symptoms. This is achieved by initially using an undersized balloon and successively a bigger if needed. An aggressive approach is prone to higher complication rates. Renal artery stenting is mainly reserved for post-angioplasty complications. PTA has shown a patency rate of 87% over ten years [6]. Patients can present with a recurrence of symptoms due to restenosis or new areas of stenosis. Previous studies have shown about 9% recurrence rate [7]. The use of cutting balloon technology has been used mainly in resistant lesions.
Teaching point: Endovascular therapy is a highly effective technique in a patient with fibromuscular dysplasia of the renal arteries. Recurrence of the condition can occur requiring a reintervention. An over-aggressive approach has to be avoided.