Teaching Case

Fibromuscular dysplasia causing stenosis of the right renal artery

Patient had been suffering from hypertension for a couple of years and had been under constant medication with a combination of two antihypertensive drugs. During coronary angioplasty a flush angiogram of her renal arteries were performed revealing a suspicion for renal artery stenosis. Selective angiography performed on the same day showed bilateral irregularities of the renal arteries which were mild on her left but was severe on the right showing a typical pattern of fibromuscular dysplasia with multiple pearlstringlike lesions and septa inside the renal artery (Fig. 1).

After passing the diseased segment by use of a slightly curved hydrophilically coated guidewire (Terumo Inc.), a cobra-shaped catheter was deeply inserted into the renal artery and the guidewire was exchanged for a 200 cm long noncoated conventional guidewire which was left in place (Fig. 2 a). Over the wire, a balloon catheter with a 4 cm long and 5mm wide balloon was placed inside the diseased segment ( Fig. 2 b) and was inflated for 60 seconds. After removing the guidewire, a 6 F renal guiding catheter was advanced close to the ostium of the renal artery and a selective angiography was performed showing improvement of the lumen with less prominent indentations caused by the septa. Then, all material was removed and selective angiography was repeated (Fig. 2 c). The blood pressure dropped from an average of 160/ 110 mmHg to 130/ 90 mmHg under medication. Treatment of fibromuscular dysplasia by PTA is well known. If applied on younger patients, technical and clinical success is more likely than in atherosclerotic lesions. However, there is a tendency for recurrence. In that particular case, age of the patient and a longstanding history of hypertension beared the risk that clinical response could be limited. Preinterventional testing of the success is however difficult. During the intervention, intraarterial pressure recording could be performed. Methodically, this is not so easy to perform since in small arteries insertion of a 5 F catheter may mimick a significant stenosis; use of smaller catheters of 3 F is therefore mandatory but technically challenging. Technically, balloon angioplasty of fibromuscular dysplasia can be difficult. A major problem is the successful passage of the diseased segment by a guidewire because the tip of the guidewire may be encaptured between the multiple septa. The use of a straight guidewire, a slightly bent hydrophilic guidewire or a stepwise intubation of the lumen by a catheter (Sidewinder I or II ) may become necessary. Although, involvement of multiple segmental arteries may be present making the intervention a challenge. Normally, reaction towards balloon angioplasty is favourable and dissection is not too frequent. Typically, the fibromuscular character of the artery is still present after PTA.