It depends on which form of supraventricular tachycardia someone suffer from, and more important, if someones heart is healthy or not.
A healthy heart can usually tolerate supraventricular tachycardia without problems, and usually even ventricular arrhythmias without problems. An unhealthy heart can get problems with a rapid heart rhythm, through different mechanisms. If someone suffer from coronary artery disease, the rapid heart rhythm can provoke ischemia (lack of oxygen) which again may provoke dangerous ventricular arrhythmias. If the heart is having problems filling or pumping (diastolic or systolic heart failure), stroke volume and cardiac output during a supraventricular tachycardia can drop too low, which is dangerous.
But in healthy hearts, supraventricular tachycardia is more of a nuisance. Given that the heart rate isn't extremely rapid (far above the estimated maximal heart rate) or causing problems like fainting. If it does, it's dangerous.
I had a run of supraventricular tachycardia at approx. 240 bpm once. I had no problems but it felt terrible.
Yes, pretty fast. At least now I know that my heart is able to handle that. It happened when walking up a hill along with a panic attack because I felt ectopic beats. When I stopped the heart rate slowed down in seconds.
I had 54 year of SVT with rates rangin from 200- to over 300 bpm. As a year old kid, I was clocked in the hospital at 312bpm. I had been this way for about 24 hours. My lips and fingernail beds were bluish from from lack of oxygen as my hear was pumping too fast to completely fill before being ejected. As i_s_w states, SVT on a healthy heart is more of a disruption of lifestyle. I was able to compete is a variery of sports at very high levels well into adulthood. But when an episode occured, I was immediately out. An SVT episode recorded on a wearable monitor gave my cardiologist concern as he hadn't seen 250 bpm in 60 year old. His concern was whether an aging heart, despite its excellent physical condition, could withstand SVT at that rate. So I decided on cardiac ablation, and today at 62 am free from a lifetime of carrying around that millstone. While too old to compete today, I coach and still skate in a division for old guys like me who refuse to go down without a fight. If you have SVT, there is an excellent chance that cardiac ablation will provide you a cure.
Sorry.... "As a six year old kid, I was clocked in the hospital at 312bpm."
Either way 1 or 6 or anything 312 is so fast it can't be counted in real time by "ear", 5 beats per second (about/average) I can't count 1..5 in one second. Of course while we are older than most here I suppose electronic counting was available back then.
I don't do SVT, just AVT ha! Atrial VT, that is without slow down meds I'd be running well over 130 I'll guess, at rest. When I ran I and wasn't in AFib I could see 170, then had to slow down. That's about the highest I've experienced and it was due to physical stress, not a runaway clocking system.
I don't have any thing to really add, I opened and read to learn, then just can't help trying to relate.
The recommendation I take away is discuss an Ablation with the doctor... EP best.
1957, Jerry when that happened. I remember standing in in front of a florescope no doubt getting dosed with a lifetime of microsieverts in one exam. They converted me with blast of intravenous delivered digitalis; brutal, crude tools by todays standards.