“String of Beads” Appearance of Bilateral Brachial Artery in Fibromuscular Dysplasia
A 56-year-old woman presented with chest discomfort and underwent coronary angiography via a transradial route. Left brachial artery stenosis was suspected because of difficulty in passing with a 0.035-inch guide wire. Upper-extremity angiography showed presence of multiple stenoses and aneurysmal dilatations in her brachial artery (Figure 1). Subsequent to catheterization, the patient received duplex scanning using Aplio SSA-700A (Toshiba, Tokyo, Japan) using the advanced dynamic flow mode. This mode is associated with high resolution, wide dynamic range, and high frame rates and is capable of producing a superior angiograph-like vascular image. Duplex scanning showed serial stenoses alternating with aneurysmal dilatations over a length of approximately 10 cm in her bilateral brachial arteries, which is a typical “string of beads” appearance of fibromuscular dysplasia (FMD)1 (Figure 2).
FMD usually affects the renal and carotid arteries, and brachial artery involvement is very rare. To our knowledge, there have been only 4 cases of FMD involving bilateral brachial arteries reported thus far in the literature.2 Pathologically, 3 main types of FMD have been identified, which include intimal fibroplasia, medial FMD, and periarterial fibroplasia.3 Among these, medial FMD is the most common, accounting for 70% to 95% of all fibromuscular vascular lesions.1 As shown in Figure 2, arterial narrowing within the “string of beads” segment is caused by protrusion of the dysplastic arterial media, whereas aneurysmal dilatation results from deficit of the arterial media. Although FMD is a histological diagnosis, its diagnosis is usually made by angiography with a high degree of accuracy on the basis of the “string of beads” appearance. Ultrasound examination with advanced dynamic flow mode produces superior angiograph-like images and appears to be useful for noninvasive diagnosis of FMD.