Adrenal Venous Sampling

Background and indications

Adrenal venous sampling (AVS) is the reference examination to differentiate unilateral from bilateral aldosterone hypersecretion in patients with primary aldosteronism (Conn syndrome). This distinction is crucial as it determines treatment: unilateral adrenalectomy for unilateral production (adenoma) versus medical therapy (spironolactone) for bilateral production (hyperplasia).

AVS is indicated in patients with confirmed primary aldosteronism (elevated aldosterone-to-renin ratio, positive confirmatory test) who are surgical candidates and in whom imaging (CT, MRI) cannot reliably determine lateralization.

Pre-procedure assessment

Assessment includes biochemical confirmation of primary aldosteronism, adrenal CT, discontinuation of interfering medications (spironolactone stopped 6 weeks before, other antihypertensives adjusted), and coagulation panel.

Procedure

Under local anesthesia, a catheter is introduced through the right femoral vein. Under fluoroscopic guidance, the interventional radiologist selectively catheterizes the right adrenal vein (most technically difficult as it is small and drains directly into the inferior vena cava) and left adrenal vein (draining into the left renal vein). Samples are obtained from each adrenal vein and peripherally (inferior vena cava). Cortisol and aldosterone are measured on each sample. A selectivity index (adrenal vein cortisol / peripheral cortisol > 3) confirms correct catheterization. The procedure takes 45 to 90 minutes. ACTH stimulation (cosyntropin) may be used to increase reliability.

Results and scientific evidence

ACTH-stimulated AVS offers 85-95% bilateral successful catheterization rate and 90-95% lateralization accuracy (Rossi et al., Hypertension, 2014; DOI: 10.1161/HYPERTENSIONAHA.113.01629). It changes therapeutic decision in 25-40% of cases compared to imaging alone, highlighting the insufficiency of CT alone for lateralization. A lateralization ratio ≥ 4 is considered diagnostic of unilateral production.

Risks and complications

Femoral puncture hematoma (< 3%), right adrenal vein rupture (1-2%, generally without clinical consequence, managed conservatively), adrenal hemorrhage (< 0.5%). Major complications are rare.

Recovery

Bed rest 2-4 hours. Return to activities the following day. Results available within 3-7 days. A synthesis endocrinology consultation determines the therapeutic strategy.

Practical information

The procedure is performed as an outpatient or short inpatient stay depending on the case. It is performed by an experienced interventional radiologist, in coordination with the endocrinologist and surgeon.