Selective Venous Sampling (SVS)
Selective Venous Sampling (SVS) is unique in that we consider to be an invasive localization study. By that we mean that a catheter is placed in the right groin area and then threaded through the vein all the way up to the upper chest and lower neck in the areas surrounding the thyroid. Under X-ray the location of the catheter tip is confirmed by injecting contrast and confirming the tip location. From each separate area here samples of blood are obtained and sent for PTH testing to map out where the highest concentration of PTH is and indicate the general area where the overactive parathyroid may be.
This technique is further refined by having the rapid PTH test so that the radiologist can further focus on areas that have higher PTH levels to get more samples and try to more precisely locate the abnormal overactive gland. It is rare to have this procedure done before any parathyroid surgery has been performed because of it is a very involved & invasive procedure. So it is often used after a person has had a failed parathyroid surgery. But in fact after a previous surgery (in the figure the right superior parathyroid was perilously removed and the blood vessels to it closed) SVS becomes less reliable because the blood vessel anatomy of the area becomes altered; some blood vessels get closed off (ligated) during surgery and new ones form, in time, after surgery. So the blood vessel anatomy becomes more complex and SVS becomes less reliable, so much so that it is now rarely used.
An example of a case where I have found it to be helpful is in a person who has had previous total parathyroidectomy and auto-transplantation of a parathyroid into the muscle of the left forearm, who years later develops elevated calcium and PTH. It is not clear if this person has elevation due to over functioning of the autotransplanted parathyroid in the left forearm or if there was a fifth gland in the neck that was not discovered originally. SVS was able to show that high PTH was from the blood vessel coming from the arm and so the surgery could be focused on that area.
PROS – 1. Very accurate in a person who has never had surgery in the neck.
2. Can show the general area of the overactive parathyroid gland in the neck and chest.
CONS – 1. Exposure to radiation.
2. Not reliable in a person who has had previous neck surgery (previous parathyroidectomy or thyroidectomy).
Contact The CENTER For Advanced Parathyroid Surgery Today
Dr. Larian is an experienced parathyroid surgeon in Los Angeles with over 2 decades of experience in hyperparathyroidism surgery. unique knowledge in parathyroid gland diagnostic testing and the meaning and ramifications of parathyroid gland testing for patients suffering from HPT. Dr. Larian is happy to perform localization studies to help a patient diagnose HPT. And if a patient is dealing with HPT, Dr. Larian can provide a custom treatment recommendation.
If you feel as though you may be experiencing parathyroid problems and would like to
speak with an expert parathyroid surgeon today, we encourage you to contact our
CENTER by calling 310.461.0300 to set up an initial consultation.