I would suggest getting a thirty day monitor as opposed to a 24 or 48 hour holter. this way you have 30 days to try and catch it. I had a holter first to try and catch mine but didn't have an episode the day I had it on. I had one the day after so ask about getting a 30 day because the only way to know for sure what it is, is by catching it. But I would not rule out simple svt. I had the type called AVNRT that was caused by extra muscle fiber around the avnode. That type can cause the heart to beat extremely fast in the 200s but there are other types like WPW which could mean the rentry circuit spans the whole of the heart and present at slower rates. I know mine felt manic fast, started and stop in one beat and made me feel like I would pass out though I never did.
The fact you have some tricuspid regurgitation could indicate some scar tissue coming into play but which could lend itself to NSVT but since you aren't actually passing out it very well is svt. I know that the pvcs would be what triggered me into an svt episode and having an svt episode would irritate my heart and cause more pvcs for a time so just try your best to stop any episodes as soon as you can if they don't stop quickly. Holding your breath and bearing down like you are straining to go to the bathroom. Drinking a cold glass of water or even pouring cold water over your head. Or coughing may help break the pattern your heart is caught in. But at this point it is important to get it captured so that the cardiologist can see what the heart beat looks like. they would be able to tell then if it is simple svt or vt or something else. Best of luck and if the first monitor doesn't catch anything just keep trying.
I have some VERY similar experiences to you, except I don't feel dizzy or like I'm going to pass out. However, I experience these episodes multiple times a day, sometimes even multiple times an hour. I have skipped beats throughout the day (my last 48 monitor should over 1500 PVCs and 600 PACs), 70 came in couplets and I had 2 episodes of triplets PVCs (3 skips in a row) which was classified as Non-Sustained Ventricular Tachycardia. However, I also had multiple short episodes of SVT throughout the day (average was 16 beats at 131 BPM). I was told by an ER doctor that since my racing was under 150 most of the time, it probably wasn't SVT because that would be atypical. Guess what, I'm atypical. Usually, my SVT is triggered off of a skip. It skips than takes off racing. The reason why most of my SVT runs were around 16 beats is that I've gotten very good at catching them and stopping them quickly. As soon as it starts racing, I take a few slow DEEP abdominal breaths. That usually stops it. If that doesn't work, I hold my breath and bear down from your chest run down to your butt. If THAT doesn't work, I press on my eyeballs (not usually recommended by doctors because if there is risk of damaging your eyes if you press too hard, but if nothing else works, this one will do it for me. My paramedic relative told me about this trick). All of these maneuvers stimulate your vagas nerve and cause your parasympathetic system to kick in and slow your heart. Good luck! I'm also in the testing phase of a diagnosis and heading for a stress test and echo next month. Oh, and I also suffer from a panic disorder and know how badly these things can trigger your anxiety, which in turn just makes things worse. I take magnesium citrate and taurine at night to help with the anxiety ( I also had Xanax to take as needed.... and when the symptoms really act up... I do need it). Good luck!
Just as an update, after many echos, ecgs, stress tests, and holter and event monitor results were normal but showed random high spikes of sinus tachy up to 180, I was referred to an EP. Met with the EP and have been diagnosed with Inappropriate Sinus Tachycardia. Switched high bp meds from atenolol to candesartan and also added metoprolol for the sinus tachy. Hopefully this will help. Follow up in a month.