Hi I'm 49 and have had heart problems since I was 39. (stints 98 and they calasped in 99 so had double bypass 2000. then Aug of 09 had stint.Just had test and they where abnormal so had heart cather done .Just started Isosorbide mononitrate 30mg er.After have a heart catheterization .I have already been on 2 other blood pressure pills(Metoprolol tartrate 25mg 1 at p.m and take Lisinopril 2.5mg in am. My concern is my blood pressure dropping to low... Is all 3 of these to much? and How low should it get before I call the doc? thanks