fata,
When we refer to the function of the heart at any given moment, it is generally reflective of the conditions effecting the heart at that time. Thus, the heart is a pump and anything to optimize the function of the pump can imporve or worsen the efficinecy of the pump. Thus, diastolic function if measured on an echo is a picture of the diastolic function of the heart at that moment with that blood pressure and heart rate. So any medication such as a diuretic which changes the volume that the pump has to move, or a blood pressure medication which changes the pressure the heart pumps against can change the function of the heart from one point to the next.
The issue of the pulmonary hypertension should be examined further. It is not just a diagnosis that happens. If your cardiac evaluation is normal other things such as rheumatoloic diseases and sleep apnea should be examined.
good luck
Also, given the seriousness of these some of the possible outcomes, as well as the difficulty of makeing the diagnosis --- from what I read, Pulmonary Hypertension is often missed --- I believe I would be very careful with your approach to managing your medical care. 2nd and 3rd opinions are good, but be sure all doctors share information, and understand what you are asking them to do.
You are/should be looking for a complete assessment, and a comprhensive strategy for dealing with it, not for an assessment bounded by the doctor's area of specialization, and lacking a plan of action (A plan that says "do nothing" is ok, as long as that approach has been weighed against other rational approaches). So it is good to have at least one doctor who is aware of all findings and is helping you do some thinking.
Regards,