Ok thanks for the additional symptoms well enlargement of the pulmonary artery by itself is not something to wory about as there are a number of congenital anomalies which could lead to asymptomatic enlargement of the artery. But the important thing here is that you have the enlargement alongwith symptoms which can be consistent with that of pulmonary hypertension.
The shortness of breath which increases on exertion and the fact there is high pulse rate and increased coughing all point towards the diagnosis. In addition since you have had the echo this would have shown the increased PAP which is pulmonary artery pressure. Now what is the cause for this? at such a young age the cause is ually congenital anamoly of the artery which leads to its enlargementor even collagen vascular diseases such as scleroderma etc which leads to gradual thickineing of the artery due to deposition of fibrous material and thus leads to the enalrgement of the pulmonary artery. yet another rare cause is that of an idipathic pulomart artery aneurysm which should be picked up on a CT scan of the chest. This is a very rae cause and studies have shown this to occur in young patients as well. Im mentioning this here because if no other cause is found then this should be considered. Ill paste a link here for a study regarding this last condition,http://www2.umdnj.edu/~shindler/padil.html
You can show this to your doctor and ask for his opinion on this.
Now the other causes of PAH (pulmonary artery hypertension) like collagen vascular diseases or vasculitis must be ruled out with tests like ESR, ANA, CRP, ANCA etc etc. This can be done if you have any other evidence of the disease. If you dont have any cause which can be found then this will be termed as idipathic hypertension.
Now the treatment for this is varied and depends on the pressure and the symptoms as well,
Diuretics like lasixVasodilators
like calcium channel blockers (procardia)Sildenafil
Epoprostenol which also dilates the arteries and reduce the pressure
the important point here is that treatment needs to be started early and to prevent the occurence of failure of the right side of the heart. Here is some more information on this conidtion,
I hope this helps you out
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