Is Desmopressin the same as Vasopressin

My 10 year old (has Long QT Syndrome) has a bedwetting problem that has progressively gotten worse over the past couple of years. Our pediatrician wants to give him Desmopressin nasal spray and he told me that it does not interfere with LQTS. I haven't checked it out with our EP yet, and I looked it up on the Long QT drug list and it says to avoid Vasopressin. I read that Desmopressin is a synthetic form of Vasopressin and is different. Would Desmopressin  cause the same effect as Vasopressin in someone with Long QT Syndrome and should it be avoided? I have also read that it is not being used for bedwetting in the UK anymore as it can cause low sodium and excessive water retention. Wouldn't causing low sodium be bad for someone with LQTS also?
Thanks

[Forum-M.D.-CA]

Desmopressin is a synthetic agonist of Vasopressin which acts on V1 receptors on the renal collecting duct to decreased the volume of urine and also decrease thirst by inducing hyponatremia. After consulting lists of drugs not to be used by people with LQTS I did not find either vasopressin or desmopressin, so I am assuming it is acceptable to use this drug. However, the benefit of th drug is likely not to be very significant, and in studies the improvement in bed wetting was minimal.
I don't know several things about your son: first does he have defibrilator and second what subtype of LQTS does he have. Depending in the answers to these questions he may be protected from VT/VF and use of the medication may be acceptable. But I would say that since the benefit from it is so small from the medication that I would advise you not to take it.