Intravascular ultrasound evidence for coarctation causing symptomatic renal artery stenosis

Background-A recent study of human cadaveric renal arteries revealed that r enal artery narrowing could be due not only to atherosclerotic plaque compe nsated for by adaptive remodeling, but also to hitherto undescribed focal n arrowing of an otherwise normal renal arterial wall (ie, coarctation). The present study investigated whether vessel coarctation could be identified i n patients with symptomatic renal artery stenosis (RAS). Methods and Results-Consecutive symptomatic patients with angiographically proven atherosclerotic RAS who were referred for stent placement were studi ed by 30-MHz intravascular ultrasound before intervention (n=18) or after p redilatation (n=18), Analysis included assessment of the media-bounded area and plaque area (PLA) at the most stenotic site and at a distal reference site (most distal cross-section in the main renal artery with normal appear ance). Coarctation was considered present whenever the target/reference med ia-bounded area was less than or equal to 85%. Before intervention, coarcta tion was observed in 9 of 18 patients and adaptive remodeling in 9 of 18 pa tients. Coarctation lesions had a significantly smaller PLA than adaptive r emodeled lesions (P=0.001), Similarly, despite predilatation, coarctation w as seen in 8 of 18 patients who had significantly smaller PLAs (P=0.008) wh en compared with those patients who had adaptive remodeled lesions. No diff erences in severity of RAS or angiographic or clinical parameters were obse rved. Conclusions-Low-plaque coarctation may cause a considerable proportion of s ymptomatic RAS, which is angiographically and clinically indistinguishable from plaque-rich RAS.