Abstract 002: PO 2 -guided Adrenal Vein Sampling In Primary Aldosteronism

Abstract

Background: Accurate diagnosis of laterality of adrenal aldosterone over-secretion is crucial in determining specific treatment for primary aldosteronism (PA). Although adrenal vein sampling (AVS) is considered as the gold standard method for lateralization, successful canulation to right adrenal vein (RAV) has been reported to be challenging since RAV usually empties directly into inferior vena cava (IVC). In addition, the entrance of RAV is close to that of hepatic vein (HV) or opens to a common trunk with HV in up to 20% of the patients with PA. Cortisol step-up and other proposed indices are not always available during the procedure. Method: AVS was performed in confirmed PA patients between January 2021 and April 2022 at Tohoku University Hospital. During AVS, a small portion (0.3mL) of the sampled veins (RAV, IVC and HV) were analyzed with a blood gas analyzer for partial pressure of oxygen (pO 2 ) measurement. Result: A total of 120 AVS was performed. After excluding inappropriate samples, further analyzed were 120 samples of IVC, 107 of RAV, 116 of HV before cosyntropin stimulation, and 120 samples of IVC, 117 of RAV, 115 of HV after cosyntropin stimulation. We observed an average of 22 mmHg increase of pO 2 in RAV than IPV, and 28 mmHg increase than HV before stimulation. The difference between RAV and IPV was 15 mmHg in average and that of RAV and HV was 22 mmHg after stimulation. Similar pO 2 step-up was also observed between left adrenal vein and left inferior phrenic vein. Discussion: Here we describe prominent pO 2 step-up in both adrenal veins compared to neighboring non-adrenal veins and peripheral blood. pO 2 measurement is easier, faster, less expensive, and requires a very small amount of sample, can be performed by routine equipments in angiography suite, compared to other selectivity indices for successful cannulation in AVS. This would also contribute to reducing unnecessary blood sampling, radiation exposure and repeat AVS. pO 2 step-up in adrenal vein suggests low oxygen consumption in adrenal glands, which potentially contributes to survival advantage in systemic hypoxic conditions. We propose novel pO 2 -guided AVS especially in patients with difficult RAV anatomy and in unexperienced centers.