On the night of shvii shel Pesach, or Aharon shel Pesach, a person accidentally recited, or began reciting, the bracha of Shehecheyanu. Is this a hefsek that would require him to repeat borei pri hagofen prior to drinking the Kiddush wine or grape juice, since this bracha does not belong in Kiddush?
When should he say Baruch sheim kevoid malchuso leolam vo’ed on his bracha l’vatala (immediately, or only after drinking the wine)? If the answer is that he should say it after drinking, what should he do if he accidentally said it before drinking?
Would it make a difference what exactly the situation was – for example, he already said the entire bracha (G-d forbid), or he said “Baruch ato Hashem” and ended off with “lamdani chukecha,” which is a verse in the Book of Psalms (but which also does not belong in Kiddush)?
The bracha of Shehecheyanu is not a hefsek, bdieved. “Baruch Shem” should not be said until after drinking. If he said “Baruch Shem” it would constitute a hefsek and a new borei pri hagefen would be required. Finishing off with “lamdeni chukecha” would also constitute a hefsek, as it is knowingly saying something not connected to the kiddush, as opposed to shehecheyanu which he thought to be part of kiddush.
Mikraei Kodesh 2:62, Shmiras Shabbos Khilchisa 47:43, see Madanei Yom Tov, Pesach 124.