Subtyping of Primary Aldosteronism by Adrenal Venous Sampling

Primary aldosteronism (PA), the most common cause of arterial hypertension, is surgically curable if a unilateral source of the hyperaldosteronism is discovered. To identify which patients are curable, all current guidelines recommend adrenal venous sampling (AVS), a procedure which, albeit simple in principle, remains scarcely available and markedly underutilized, because it is still perceived as technically challenging, invasive, and difficult to interpret. The lack of uniformly accepted standards for performance and interpretation of AVS, alongside the diffuse concerns that (although quite rarely) it can be complicated by adrenal vein rupture, contribute to the scant utilization of AVS. In the last decade, several major studies have led to a greater understanding of the use of AVS in PA patients, thus paving the way to a more rational and effective application that can enable diagnosis of many more PA patients with a unilateral form of the disease to be referred for curative adrenalectomy. Moreover, microcatheters and androstenedione have been introduced to increase the success rate. This review provides updated information on the subtyping of PA by means of AVS and examines key issues on the selection and preparation of patients, the optimal performance of the procedure, and the interpretation of its results for diagnostic purposes, even in the most challenging cases. Situations when AVS can be omitted before surgery and alternative functional imaging techniques that have been proposed to identify unilateral surgical curable PA to circumvent the bottleneck represented by the limited availability of AVS worldwide, are also discussed.