If SVT that last longer than a few seconds and it’s becoming more frequent and lasting longer you need to see a cardiologist, a heart Dr and he will do an EKG, maybe a heart monitor for 30 days. It may be another arrhythmia like AFib and other more serious. So after the cardiologist gets the whole picture with all the testing, he will probably put you on a med to control your heart rate. I had the same issues at age 19 which by age 57 it was lasting up to 4 hours and wouldn’t turn off. I rested, did the bearing down exercises and drank cold water. I had to go to the ER. I was at a rate of 290 and they started an IV on me( missed 4 time), then pushed Adenosine which literally stops your heart and when it does you get this feeling of leaving this earth. Scared the 💩 out of me! They didn’t tell me what it would do! I know what it was for but I never read reviews from people who have actually had it. If it would not have worked they would have sedated me and out paddles on my heart at low voltage and do a shock or repeated shocks. So I’m thankful the adenosine worked. They had the Dr the nurses and the EMT’s standing around me in case I continued to flat line but like text book it stopped the SVT and converted me into a normal sinus rhythm which is ideal for what a normal rhythm should be. I then found a cardiologist had the monitor and the tests and was put on a beta blocker which I could not tolerate because it was dropping my BP to 60/30 and I felt weak and dizzy and I was on a low dose.I reported this to my cardiologist and he told me to drink salt water stop the metoprolol and he immediately scheduled a Cardiac Ablation” by a Cardio/physiologist. A Cardiologist who does Ablations in the Cath lab. I was off my med for three days and was in SVT at rate if 240 when they did the procedure. They gave me a little anesthesia and threaded a catheter up my right groin to my heart and Zapped! The area in my right atrium where the abnormal foci was coming from and Wala! It Worked. After seven years I have a very rare bout of SVT but very short spurts. I am on no Cardiac meds . My BP runs 110/60 and have more than better cholesterol levels because I exercise and eat healthy and have good genes. Caution, there are risks with an ablation which the Drs will explain and it could come back and you may have to have another ablation. Everyone is different. If you BP runs high normal or high a med to control your heart rate will most likely be the first choice.