The thing is, that when I do this, I get a really strange effect from it. During the valsalva you force air agains a closed
glottis, and hold that pressure for maybe 10 sec.
When i release the air, my heart acts REALLY weird. It takes long pauses, and then beats really hard, then fast for a few beats again, then another break and a hard beat, and then after maybe 30. seconds, it goes back to a steady, normal rhythm.
Those thirty seconds are terrible.