Panic Attack with no elevated heart rate?

So this one was new for me and wondering if it's happened to anyone before: early this morning I woke up just fine and went to use the restroom. While sitting on the pot for a few minutes (maybe 3 or 4) I suddenly got that familiar anxiety/panic attack feeling of lightheadedness and body tingles I stood up, but not too fast, and splashed some water on my face. and made my way to the couch as I felt I was going to pass out. I've been here before but, as the title suggests, my pulse didn't go up much higher than normal. I don't remember ever experiencing this before. Does anyone else run into this? Honestly, it scared me a little as it didn't follow what I expected.

Just curious if this is common, or at least not unusual, for others.