I'm new: What reasons could my heart be experiencing exercise-induced tachycardia and difficulty breathing? None of the conditions match?

[passionaterunner]

With COVID-19, it is hard to find a cardiologist that has time or space. Any insights or similar experiences would be greatly appreciated. I am a college-aged individual that is active (half marathon runner, etc.).

About one month ago, I went to the ER with symptoms of a DVT- sharp calf pain, chest pain, shortness of breath, and heart arrhythmia, but all tests came back normal. They originally told me that I had an anxiety attack, but this seems very unlikely given the symptoms' persistence and documented arrhythmia that I am experiencing. In an echocardiogram, I was found to have an atrial septal aneurism and small issues with valve regurgitations. The report said that these were incidental findings, and probably do not mean anything causing my symptoms.

My average resting bpm is around 52, but when I start very light exercise, my bmp jumps to 160-190 and it becomes extremely difficult to breathe. Sometimes, the symptoms last for a few days afterwards. After a 6 mile bike ride last week, my heart stayed around 130 throughout (which I thought was great). But it wasn't normal- I felt extremely fatigued afterwards and found it hard to breathe that evening. However, it took 2 days for my breathing and heart rate to lower back to my normal resting rate. It was constantly at 90-120 and jumping all around.

I frequently have chest pain and tightness, but this isn't always correlated with my physical exertion. What is so frustrating is that one month ago, I had no such problems and exercised for 60 min almost every day with no issues. I don't understand what is going on, and I am scared for what this means for the future. In a cardiology appointment, inappropriate sinus tachycardia was raised as a possible diagnosis, but my heart rate is not normally above 100. As I write this, my bpm is around 49-52.

Today I went for a 2 min run on the treadmill going (15 min/mile). Within 45 seconds, my heart spiked to 140-170 and stayed that way for 2 min. I stopped immediately and sat down- my heart rate plummeted to 50 and I felt lightheaded and fatigued. I felt that it was hard to breathe.

This is a very isolating experience, especially during social distancing when I can't talk to people about it. Please let me know if anyone has similar symptoms, especially if you have been diagnosed with inappropriate sinus tachycardia. And if anyone also has the ASA, let me know too if it has caused complications!!

[winter399]

Not everyone with IST has a resting heart rate over 100bpm. My cardiologist explained that you can be diagnosed if you 1) have a resting heart rate over 100bpm or 2) have a significant increase in heart rate in response to exertion/exercise (or both). It also has to cause significant disruption to your quality of life - some people naturally have resting heart rates of 110-120+, but if it isn't bothering them, they don't have IST.

He couldn't specify a number of beats per minute in terms of the 'significant increase', just that the increase is inappropriate given the exercise you're doing. Also because your fitness levels will determine what is 'inappropriate' for you.

My resting heart rate over 24h is about 85-90 unmedicated but I was diagnosed with IST because my heart rate jumps up whenever I get up and move about - up to 166bpm when simply walking. I'm not a doctor but I would say someone's heart rate going up to 160-190 with light exercise would qualify as 'inappropriate'.

[2k2d]

Unfortunately winter399 is correct. I also have IST and a resting heart rate of 54. I believe mine started in my early 30s but didn't get so bad that I noticed until I was 38 (I am almost 42 now). Mine jumps up for any sympathetic stimulation and sometimes stays high for hours. So weird... it will shoot up for things like strong emotion, laughing, eating, bending over, exercise, etc. and sometimes for no reason at all with some days being worse than others. It took a year or two to pinpoint exactly what was going on --- that it was indeed IST and no other arrhythmia. It lead to a host of other bodily issues like poor sleep, extreme fatigue, irritability, breathlessness, chest pain, weight loss, jumpy feeling, headaches, etc. Finally I found a beta blocker dosage I can live with, and it keeps the symptoms manageable. Mind you, they are not gone but livable. Even with the beta blocker, there are athletic things I just can't do anymore. My heart rate will easily hit 190 on a beta blocker if I jog lightly for over 5 minutes. And like you, I was always athletic, a former college-athlete even. I've had to learn my new body and my new limits and what works for me. I sincerely hope you are not dealing with IST, but if you want, look at some of the past posts on here so you can get an idea of what meds people have tried and other ideas. Also, see if your cardiologist will refer you to an electrophysiologist. You might could just get the ball rolling with a teledoc appointment. Good luck and keep us posted!