Doctor leaves one practice - disclosure of patient list to new practice for marketing?

[Guest BL333]

A doctor leaves one practice to join a new one. Both before and after leaving the practice, the doctor compiled a list of patient names from memory. The doctor disclosed this list to the new practice and the new practice sent out a generic notice announcing the new doctor's services to the patient list.

Did the doctor violate HIPAA when the doctor disclosed a list of patients that had been treated at the previous practice to the new practice for the purposes of the new practice's marketing? It is clear under HIPAA that a hospital or health care practice may send out such a generic notice to its own patient list. This situation seems a bit different because the patient list came from the old practice. Did the doctor need to get authorization from the patients before sharing the lists with the the new practice?

If the doctor did violate HIPAA, is only the doctor liable for possible civil monetary penalties in the case of a complaint to the Secretary, or might the new practice be liable as well for using the list?

Any insights would be appreciated! Many thanks!