Is fainting with heart rate changes normal in a teenager?

Question

Hello doctor,

I am a teenager and have a history of fainting when standing. This morning, I felt a bit dizzy. As the day went on, it got worse and worse until I felt like I was going to pass out while sitting still. My heart rate was 139. This process occurred gradually over a period of three to four hours.

I was really disoriented and could barely move. Breathing was hard, too. Thirty minutes later, I got up to catch a dog that ran onto the ride, and my heart rate dropped to 54.

At this point, I felt nauseous and hot, with flushing as well. My resting heart rate was between 106 and 83 beats per minute. I started to feel better, but then a headache started. I was still nauseous and dizzy. My heart rate is fine now, but my PI percent is 0.4.

Please help.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I have gone through your query and understand your concern.

From what you are describing, it sounds like you experienced a significant dizziness episode that built up gradually through the morning, eventually making you feel as though you might faint even while sitting still. Your heart rate rising to 139 bpm (beats per minute), along with the disorientation and difficulty breathing, suggests your body was under stress during that time.

When you suddenly got up and ran to catch the dog, the sharp drop in your heart rate to 54 bpm, followed by nausea, flushing, and feeling very hot, is consistent with a strong vasovagal response or a sudden drop in blood flow to the brain. The fact that your heart rate has been fluctuating between 83 and 106 since then and that you are still dealing with headache, nausea, and dizziness shows that your system has not fully stabilized yet.

The very low PI (perfusion index, a measure from the pulse oximeter) percentage of 0.4 on your oximeter likely reflects poor circulation during the episode rather than an oxygen problem. Given your history of fainting when standing since around age 15, this may point toward a condition like orthostatic intolerance or POTS (postural orthostatic tachycardia syndrome, a disorder of the autonomic nervous system), but you must get checked to rule out dehydration, infection, anemia, or heart rhythm issues.

If possible, please seek a medical evaluation soon, especially if the dizziness returns, your heart rate becomes very high or very low again, or you feel like you might faint.

I hope I have answered your question.

Let me know if I can assist you further.

Thank you.