Sublingual nitro -- how fast does it work?

A couple of weeks ago my cardiologist offered to rx nitroglycerin tabs (0.4 mg sublingual) to help diagnose whether my symptoms are due to ischemia or not. I've used them twice now and am having trouble deciding whether they really helped. What I mean is, my symptoms always go away eventually so how can I tell whether it was the nitro that helped relieve them? The first time was during the afternoon last week when I was having a squeezing heaviness in the center of my chest. The nitro made my heart pound and moved the center of the heaviness upward toward my throat, and gave me a throbbing headache. After a half hour I finally fell asleep, and when I woke up an hour later, the chest heaviness was gone but the headache was still there. Today I was feeling a chest congestion and burning all day, which this evening turned into a twisting feeling on the left side of my chest and neck. I took one nitro, got the same throbbing and pounding in my chest, neck, and head, but the tightness didn't begin to go away for another 20 minutes. At that point I took a xanax 0.25 mg and the pressure was more or less gone about 30 minutes after that.

So I'm wondering what others who have used nitro have experienced? Do your angina symptoms subside within a couple of minutes (that's when I feel the throbbing/pounding), or does anyone else get relief 20 minutes or more later like this? Everything I've read says it should give relief right away if at all, but I trust other people's experience over the word of "experts" in things like this.

[fizzixgal]

bump

[shell1925]

I was at my cardio on Wed. and while I was there I started having the chest pressure and left arm pain.  They gave me the sublingual nitro and told me that if it didn't work within 3-5 minutes then it is not my heart or esophageal spasms.  Hope this hopes.

Shell

[diva2008]

Well I take 60mg of Imdur in the morning and 30mg of Imdur at evening this is a long acting nitro and I also take 0.4 mg of Nitroquick when needed and it does work very quickly for me. I'm so glad I have these meds in my life. I think everyone is different in our bidy so meds will effect us differently.

[fizzixgal]

Thank you both for answering. I had a long talk with my cardiologist yesterday and he agrees, if the nitro had done anything to relieve the pain it would have been in the first 2-3, maybe 5 minutes, not a half hour later. And I definitely felt the effects of it, just no relief. I also described my symptoms from Friday night to him in detail and he doesn't think they sound anginal at all. He believes I suffer from hyperventilation syndrome and said that I could confirm that with a pulse oximeter. I don't really understand what he is getting at there. I'm glad I will be seeing a different cardiologist this week for a fresh evaluation.