Before and at the end of @ week treatment , the clinic responses of the two regimens were evaluated , plasma levels of endothelin-@ ( ET-@ ) and nitric oxide ( NO ) were determined ; arterial oxygen partial pressure ( PaO@ , mean pulmonary arterial pressure ( mPAP ) , outflow tract of right ventricle ( RVOT ) , and internal diameter of right ventricle ( RV ) were measured .