Im assuming your PDA has been assessed by a specialist and that you don't have indications for closing it and you are not symptomatic. Im sure you have had the relevant tests such as an echocardiogram. Usually in adults we close PDA's in the following settings 1) symptoms and evidence of significant blood shunting across the PDA, evidence of elevated blood pressures in the lung, enlarged heart chambers, or prior infection in the heart. The echocardiogram can assess for pretty much all of these things. So since you have been reassured the only thing needed is regular follow up with an echocardiogram every few years or so. Symptoms could include fatigue and shortness of breath. Its not that the PDA enlarges, in fact is will likely become calcified and maybe smaller. Follow up is to ensure the effects on the heart remain minimal. So you should 1) ensure echocardiographic follow up periodically to ensure no detrimental effects to the heart or lung arteries and 2) be aware of the symptoms that could occur.