I have a similar problem. I suffer from palpatation's and have been perscribed 80mg Verapamil tablets to be taken twice a day. Shortly after I take the tablet (around 10 minutes) I have symptoms of my palpatations. Light headed, pains, eratic heart beat, which lasts about an hour. I have been given 40mg Verapamil before, to be taken twice a day, and did nopt have these effects, do you think maybe that the dose is to high for me?
I think that in your case the SVT broke through the verapamil therapy. It is very unlikely that it would cause palpitations. Occasionally, when the heart rate really slows down some people feel forceful contractions which may feel like palpitations. The fullness in the neck really makes me think that you have an SVT that could be easily induced in the EP lab and easily ablated as well. You should see a cardiac electrophysiologist.