Can I attempt the Valsalva on a patient who has chest pain? What if the patient has a clear onset of palpitations, then after onset develops chest pain and or shortness of breath?
Chest pain is not technically a Contraindication for the Valsalva maneuver.
If you believe it is the latter and the patient meets all of the Indications, Conditions and none of the Contraindications for the maneuver, then it is reasonable to perform to try to abate the arrythmia and relieve the demand.
If you believe that ischemia may have proceeded the arrythmia, or that the patient will not tolerate the maneuver, despite them meeting all of the Indications, Conditions and Contraindications, it is reasonable to not perform it.
As always, please document any and all rationale.