Tachycardia and palpitations after cardioversion

I had a-fib for 6 months and had cardioversion 2 weeks ago. It went well and only took one shock. My resting heart rate is now between 62 and 75 and my blood pressure is not bad. Prior to cardioversion I would sometimes have palpitations when lying down. I also had occasions when I would wake up early with a rapid heartbeat and shortness of breath (even though I use a CPAP machine religiously). I expected these symptoms to go away after cardioversion but they haven't. I usually have strong palpitations when lying down, although they are now very regular. The tachycardia is happening most nights now, usually between 4:30 and 6:30 AM. Sometimes it is not too bad but this week I had a very bad episode so I checked my heart rate with my blood pressure machine and my pulse was 184. My blood pressure was 203/170 but my cardiologist's assistant says my machine probably cannot measure b/p at that pulse rate, which sounds reasonable, but I think the rate was accurate as it was really flying. I am taking 240 mg Cartia XT and 40 mg Benicar each night at midnight along with my Coumadin, and 4000mg fish oil in the morning. I have noticed that eating a late, heavy meal will greatly aggravate both symptoms. I am wondering if the vagal (sp?) nerve is stimulated during cardioversion and if that could be causing it. I do have a lot of gas sometimes. Maybe I should see a gastro enterologist? Another possibility is that my CPAP machine loses effectiveness during the night but I don't think that's it. I wore a halter monitor earlier this week in an attempt to catch the problem and had a mild episode that I thought would have shown up. My cardiologist has not read it yet but his assistant took a look and said she didn't see anything out of the ordinary. The palpitations are annoying but I am very concerned about the tachycardia putting me back in a-fib. I had surgery to fix my mitral valve in 2002 and my atrium is enlarged. What can you suggest? I think my doc thinks I'm crazy.

[Michael J. McWilliams, M.D.]

The answer to the fast heart rhythm is probably partly on the Holter.  It is important to see the rhythm because this could be atrial fib, atrial flutter, sinus tachycardia from panic attacks, or another arhthmia.  The hard will be figuring out if it is from panic attacks or not -- if the rhythm is normal but fast (sinus tachycardia), it suggests an anxiety or panic related cause.

There is not evidence to suggest that cardioversions affect the vagus nerve and a GI doctor probably will not be helpful in treating the fast heart rate.

Previous mitral valve surger puts you at risk for atrial flutter, but the fact that it is happening in the morning around the same time suggests panic axiety -- arrhythmias are usually not that punctual and tend to have a mind of their own.

I hope this helps.