How to manage palpitations?

Hi doctor,

I am a 46-year-old female, and I am obese. I do not consume caffeinated drinks, smoke, or use drugs. I stopped taking Lisinopril because it was causing more symptoms than it was helping. I have high blood pressure, but it became too high, so I started taking it again. I was born with a small heart murmur, but it has never bothered me. About four to five years ago, while training in mixed martial arts, I started experiencing episodes where my heart would beat too fast and then pause. At that time, I weighed about 280 to 290 pounds, was eating healthy, and worked out six to seven days a week during training, but the episodes did not last long.

In the past year, the issue has worsened, and now my heart occasionally beats hard against my sternum. During the last episode, it actually hurt slightly when my heart would hit the wall of my sternum. This time, it is been happening consistently for about a week and has not stopped. It occurs daily.

The first cardiologist I saw did not find anything abnormal after I wore a Holter monitor for two days, had an ultrasound, and underwent a few other tests. I went to the ER last week, and nothing showed up. But when I got into my car to leave, the palpitations started again. I am feeling overwhelmed and scared. Can you please help me figure out what direction I need to take?

I no longer work out because I have a reverse curve in my cervical spine and some curve loss in my lumbar spine, which has caused my lower thoracic spine to straighten a bit. I have noticed improvements in my posture, but I am wondering if my spine issues could be causing my heart symptoms since I know the innervation to the heart comes from the cervical and thoracic spine. If not, what would you suggest? By the way, I am improving my diet, drinking about 0.52 gallons of water a day, and occasionally taking magnesium.

Thank you.