Renal Artery Fibromuscular Dysplasia: Clinical Aspects and Ultrasound Diagnostics

Abstract

Fibromuscular dysplasia (FMD) is a noninflammatory and nonatherosclerotic type of vascular stenosis that affects mainly the renal and carotid arteries. The most common type of FMD is the media fibroplasia with the characteristic “string of beads” appearance. The disease must be suspected in young people, commonly women, with arterial hypertension, in the resistant hypertension and in the hypertension associated with a decrease of renal mass. Considering that the string of beads appearance generally isn't seen on duplex imaging of renal arteries, a peak systolic velocity of 285 cm/sec or a renal aortic ratio of 3.5 alone can be used in detecting >60% of renal artery stenosis. Duplex ultrasound visualization of middle third of renal arteries may be very difficult in some cases, particularly on the left side as a result of gas artifact from the colon. In these cases comparing spectral waveforms and resistive index at the renal hilum can be helpful. Catheter based angiography remains the most accurate imaging to diagnose and evaluate FMD. Balloon angioplasty alone of the renal arteries is the treatment of choice of hypertension due to FMD and should be considered in patients with a recent onset of hypertension in whom the goal is the cure of hypertension, in those in whom blood pressure control is difficult to achieve and in those who have lost renal volume because of ischemic nephropathy.