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What causes rapid pulse rate in the middle of night?

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Internal Medicine Specialist
Practicing since : 1981
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I have been waking up with a rapid pulse in the middle of the night in excess of 160+ bpm. I have mitral valve syndrome that was diagnosed some 30 years ago and have had often bouts of PVS's and tachycardia with chest pain in the past. The rapid pulse lasts approximately 4-6 minutes and then brakes on it's own. I am 61 y/o with no other history. I am on atenelol 25mg for PVC's which I have had since the age of 18 y/o. I don't seem to wake up from the tachycardia but from something else, noise, first aid pager, door slamming etc., then the attack seems to come on. I have seen my cardiologist and have had a holter and event monitor on for approximately a month and did not experience an attack within this time. I guess I am worried because an an EMT I know if a rapid pulse continues for an extended amount of time and does not break on it's own, I could have a heart attack or arrest. I am not self diagnosing but am concerned that it might be SVT. I have no symptoms during the attack, chest pain, SOB, fainting and am not diorphoretic. I do notice that if I sit down and compose myself the attack is of shorter duration, rather then getting myself in a panic and increasing the rate more. I never get these attacks during the day. I am a very slender active, non-smoker, with a hot-wired nervous system as they call it. have no problem during sports, kayaking, hiking etc. My last echo and stress test was approximately three years ago, and during that time I was having these night episodes of tachycardia. The test results were "equiviable", but my doc stated to me that he is not really worried about heart disease, and unless we can document these episodes, it is difficult to see what kind of arryth. I am experiencing. He further states that if I should experience prelonged episodes or symptoms attached to the episodes, dizziness, chest pain, fainting etc., to be transported to the hospital for evaluation.
Posted Mon, 4 Aug 2014 in Heart Rate and Rhythm Disorders
 
 
Answered by Dr. Karen Steinberg 5 hours later
Brief Answer:
Rhythm needs documentation

Detailed Answer:
Hi,

Thank you for using Healthcare Magic.

It sounds like you have had a thorough evaluation by your cardiologist. Unfortunately the rhythm has not been caught on EKG so no definite recommendation can be made about it. It certainly could be an SVT, including atrial fibrillation. It is reassuring that you do not have associated symptoms with it. Certainly if you do you need immediate transportation to the ER as your doctor said. If you can get to the hospital while you are having the rapid heartbeat, they might be able to catch it that way. I'd also suggest that you discuss with your cardiologist doing another event monitor until the rhythm is actually seen, so you know what you are dealing with. If it's something like paroxysmal atrial fibrillation, particular treatment might be needed.

I think what the EMT is referring to is if the rapid rhythm does not stop over a very long period of time, eventually blood flow to the heart might be compromised and a heart attack may result. Your own doctor does not seem to be concerned about this possibility based on your previous studies, but does mention your need to be seen immediately if you experience certain symptoms with the rapid pulse, which I agree with. Again, if you can get in during an episode even if you're not having symptoms, they might be able to catch the rhythm.

I find it interesting that this only occurs at night and you don't know it unless you are awakened by something and then it starts. Is it possible you have sleep apnea, and when your oxygen level drops too low, you awaken then and then experience the rapid pulse? Sleep apnea is commonly associated with atrial fibrillation. And sleep apnea does not always occur in obese people. (I am a perfect example of that- I am your age and slender, and have moderate sleep apnea.)

These are the steps I would have you take if you were my patient:
1) Get an event monitor until the rhythm is documented
2) Try to get into the ER as soon as the rapid pulse starts, if possible, so the rhythm can be documented
3) Talk to your cardiologist about electrophysiologic studies that might be able to diagnose the arrhythmia if it can't be caught on a EKG
4) Strongly consider a sleep study to see if there is any evidence of hypoxia occurring during sleep that might set off an arrhythmia if it got severe enough.

The key thing is to determine what the arrhythmia is and what might be setting it off. Since it's been 3 years since your last studies and it's still occurring, I think it's a good idea to repeat them in any case.

Hope this answers your query. If you have further questions, I would be happy to answer them.

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