The left adrenal vein: An important direction for right adrenal venous sampling

This study aimed to evaluate the guiding role of left adrenal vein (LAV) for right adrenal venous sampling (AVS). A total of 347 patients who were diagnosed with primary aldosteronism (PA) and underwent successful AVS procedures from January 2020 to July 2021 were retrospectively analyzed. According to the different quadrant position of the orifice of right adrenal vein (RAV), the area where the orifice of RAV is located is divided into three areas: A, B, and C and the area A is further subdivided into A1, A2, and A3 areas. By counting the area where the orifice of RAV is located, the guiding role of the LAV on the RAV is determined. Most of the orifice of RAV are located in area A, and the proportions of areas A, B, and C was 96.8%, 1.4%, and 1.7%, respectively. In area A, areas A1, A2, and A3 account for 80.9%, 17.0%, and 2.1%, respectively. High body mass index, female and smaller the angle between the LAV and horizontal line was associated with the closer positional relationship between the LAV on the RAV. These findings suggest that most of the horizontal position of the RAV orifice is close to the horizontal position of the most distal end of the LAV, which indicate that the LAV location can play an important role on the guiding for right AVS. Additionally, body mass index, sex, and the angle of the LAV was largely related to location of the orifice of the RAV.

Use the right kidney contour as a landmark in adrenal vein sampling

Adrenal Vein Sampling (AVS) is the gold standard for categorizing primary aldosteronism (PA). However, catheterization of the right adrenal vein (RAV) is challenging due the small size and variable location. This study aims to explore the relationship between the RAV orifice and the right kidney contour (RKC) on fluoroscopy, thus evaluating the potential of use the RKC as an anatomic marker for localizing RAV. Imaging data of 107 PA patients with successful bilateral AVS were retrospectively analyzed. Based on the body mass index (BMI), all patients were divided into the Normal Group (BMI < 24 kg/m²), Overweight Group (24 kg/m² ≤ BMI < 28 kg/m²) and Obese Group (BMI ≥ 28 kg/m²). At the anterior view, the height level of RAV orifice was determined relative to vertebral bodies and disks. The distance from the RAV orifice to the upper edge of RKC was measured manually. The RAV orifice height level was mainly distributed from vertebral T11 to T12 (90.6%), and tended to be higher in patients with a larger BMI. The mean distance from the RAV orifice to the upper edge of RKC was 13.9±7.8mm, and had no difference among Normal group (n = 53, 14.1±8.2mm), Overweight group (n = 39, 13.7±8.0mm), and Obese group (n = 15, 13.9±5.5mm) (p = 0.981). Based on these findings, the RKC might be used as a landmark for localizing RAV on fluoroscopy, which is conductive to narrow down the exploration range and increase the success rate of RAV catheterization.

Difficulty factors of adrenal venous sampling based on patient characteristics and imaging findings

BACKGROUND

Primary aldosteronism is one of the most common causes of secondary hypertension. Unilateral primary aldosteronism can be treated with adrenalectomy; therefore, determining laterality is essential, for which adrenal venous sampling is considered the gold standard. However, as catheter insertion and sampling at an appropriate venous point is occasionally difficult, it is a time-consuming procedure.

PURPOSE

To evaluate the patient characteristics and imaging findings that influence the adrenal venous sampling procedure.

MATERIAL AND METHODS

A total of 69 patients who underwent adrenal venous sampling between January 2013 and December 2017 were retrospectively analyzed. The procedure was considered difficult if the duration was > 142 min (mean ± standard deviation [SD] of procedure time in this study) and/or proper sampling failed. Anatomical factors such as belly diameter, presence of adrenal nodules, diameter of the right adrenal vein and inferior vena cava, ratio of the diameters of the right adrenal vein to diameter of the inferior vena cava, vertical direction of the right adrenal vein, and vertebral level of the right adrenal vein were evaluated as predictive factors on computed tomography.

RESULTS

Fifteen patients (21.7%) were considered difficult cases. The factors associated with difficulty were the long transverse diameter of the belly (P = 0.004) and high vertebral level of the right adrenal vein (P = 0.032). No statistical differences were observed in any other factors.

CONCLUSION

The long transverse diameter of the belly and high vertebral level of the right adrenal vein may prevent completion of the adrenal venous sampling procedure.

Evaluation of right adrenal vein anatomy by Dyna computed tomography in patients with primary aldosteronism

Primary aldosteronism (PA) is the most common cause of secondary hypertension and consists up to 11% of patients with hypertension. Adrenal venous sampling (AVS) is the recommended procedure for diagnosis of PA, but the technique is difficult and the right adrenal vein is especially hard to catheterize. We retrospectively examined the clinically relevant anatomy of the right adrenal vein in a sample of 66 PA patients with technically successful AVS and distinctly-opacified right adrenal veins in Dyna computed tomography (CT). In the majority of cases: the right adrenal veins were catheterized when the catheter tilted posterior and rightward (57/66, 86.4%), the transverse direction of the right adrenal vein from the inferior vena cava (IVC) was posterior and rightward (55/66, 83.3%), and the vertical direction of the right adrenal vein from the IVC was caudal (52/66, 78.8%). This study shows that Dyna CT is able to provide detailed anatomical information to the course and direction of the right adrenal vein.

A review of the anatomy and clinical significance of adrenal veins

The adrenal veins may present with a multitude of anatomical variants, which surgeons must be aware of when performing adrenalectomies. The adrenal veins originate during the formation of the prerenal inferior vena cava (IVC) and are remnants of the caudal portion of the subcardinal veins, cranial to the subcardinal sinus in the embryo. The many communications between the posterior cardinal, supracardinal, and subcardinal veins of the primordial venous system provide an explanation for the variable anatomy. Most commonly, one central vein drains each adrenal gland. The long left adrenal vein joins the inferior phrenic vein and drains into the left renal vein, while the short right adrenal vein drains immediately into the IVC. Multiple variations exist bilaterally and may pose the risk of surgical complications. Due to the potential for collaterals and accessory adrenal vessels, great caution must be taken during an adrenalectomy. Adrenal venous sampling, the gold standard in diagnosing primary hyperaldosteronism, also requires the clinician to have a thorough knowledge of the adrenal vein anatomy to avoid iatrogenic injury. The adrenal vein acts as an important conduit in portosystemic shunts, thus the nature of the anatomy and hypercoagulable states pose the risk of thrombosis.