I heard back from the neurogenetecist about the concerns with Abby's breathing and heart. While they assured me that no heart defects are associated with RS (which I knew) it might be time to get a pulmonology workup. They would be able to assess her breathing issues and decide what route we should take in terms of checking her heart.
So on to yet another specialist. There isn't a huge hurry since the concerns are not terribly serious. So on we go.