Ventricular Tachycardia
Tachycardia is a condition where the heart is beating too fast (over 150 BPM) to actually pump any blood. (What is normal for a hummingbird, is not for a human). Brief episodes -- one or two seconds -- aren't noticeable but any longer runs can result in faintness, weakness ... or complete unconsciousness or death. Basically, it's not fun.
There is a (stunt) yoga practice known as "stopping the heart" because there is no discernable pulse. What the very unwise yogi is actually doing is inducing a voluntary state of tachycardia ... from which they hope to recover. I do not do "stunt yoga" (as I have assured my cardiologist and surgeon) because I am not stupid.
(Note 1: Actually, I can do some stunt yogas as demonstrations but I do not practice or demonstrate any which endanger my physical health ... no matter what it might appear.)
(Note 2: cobras are deaf and I can't play a flute anyway ... but it doesn't matter -- they still find me "charming".)