Usefulness of intervention using interlesion pressure ratio in renal artery stenosis due to multifocal fibromuscular dysplasia: A case report

Background Renal artery stenosis (RAS) due to fibromuscular dysplasia (FMD) is a known cause of secondary hypertension. Percutaneous transluminal renal angioplasty (PTRA) is an established treatment. However optimal procedural endpoints remain controversial. The Pd/Pa ratio—the mean distal renal artery pressure (Pd) to the mean aortic pressure (Pa)—has been proposed to guide interventions, its role as an endpoint remains to be validated. This report describes the clinical utility of the Pd/Pa ratio in our patient. Case Summary A 36-year-old Asian woman presented with incidentally diagnosed hypertension (185/115 mmHg). Medical and family history were unremarkable. Despite antihypertensive therapy with ARB and calcium channel blocker-measured blood pressure (BP) remained uncontrolled. Renal ultrasonography revealed a high peak systolic velocity in the right renal artery, and 3D-CT angiography revealed early bifurcation of the right renal artery and suspected stenosis in the lower pole branch. Angiography confirmed multifocal (beaded) stenosis, typical of FMD. The preprocedural Pd/Pa ratio was 0.44. PTRA was performed using two balloon sizes without stenting. Despite slight angiographic changes, the postprocedural Pd/Pa ratio improved to 0.84. At one-year follow-up, BP was well-controlled with monotherapy and renal Doppler findings normalized. Discussion This case demonstrates the clinical utility of Pd/Pa ratio as a physiological endpoint in PTRA for FMD-related RAS. Multifocal FMD, angiographic assessment may underestimate hemodynamic improvement; however, a substantial increase in the Pd/Pa ratio, even below the conventional 0.90 threshold, may indicate procedural success. Applying the Pd/Pa ratio may avoid stenting in small-calibre vessels, and favor long-term BP control.