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Some "light" info on cardiac physiology and PVCs

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Posted 1/20/2008 10:03 AM (GMT 0)
I see a lot of posts about concerns regarding arrhythmias. Right now I am learning probably more than I can handle about cardiac physiology in med school, so I thought I might share some highlights.

Your heart has four chambers. I like to think of it as a small house. There's an "upstairs" (right and left atria) and a "downstairs" (right and left ventricles). There are many areas that can "set the pace," so to speak, of your heart rate. The major pacemaker in the heart is the sino-atrial node (SA node) in the right atrium. If for some reason that node fails, there are back-up mechanisms in place to make sure the heart goes on beating. One is the atrio-ventricular node (AV node), which is situated pretty much right in the center of the house. If that fails, there are spots all over the ventricles (the "downstairs") that will then begin setting the pace. So you are very protected by your heart!

A common complaint is premature atrial contractions (PACs) or premature ventricular contractions (PVCs). These happen in everyone at some point or another and are not normally a cause for concern. The reason that PVCs occur is because sometimes those spots all over your ventricles that have firing potential actually start firing - these are called "ectopic beats." They tend to be associated with increased stimulation (like caffeine, increased sympathetic nervous system activity - like when you are suddenly scared, or just anxious - alcohol, and other irritants). So you get a heartbeat that comes too rapidly, and then there is a "pause" before the next beat...which allows more time for the ventricles to collect more energy for the next beat, which sometimes comes as a big ol' THUD. Some people feel them as palpitations, "skipped beats," or just lightheadedness; other people don't even know they are occurring. If you feel them all the time and they are troubling you, it is worth getting an EKG or holter monitor to check them out to make sure they are not "pathological" (i.e., disease-induced); most of the time they are not.

I know it seems crazy that something so stressful-feeling can be considered "benign," but yes, it's true. I myself have suffered PVCs since my teenage years and they can be very troubling, especially if you don't know what's happening.

If you've been checked out and your PVCs are benign, there are a couple of things you can do to relieve the symptoms of them. First, try your best to ignore them by distracting yourself. Watch a funny movie or go walk the dog or something. If you're having a hard time doing that, try jumping on the treadmill for a few minutes to get your heart rate up; this will sometimes coerce your heart back into regular rhythm. Third, you might ask your doctor for a beta-blocker. Beta-blockers can reduce those ectopic beats and provide a lot of relief. Unfortunately, they also have the tendency to reduce heart rate and contraction force, so they are not a good idea to use in people who already have a slow heart rate (60 bpm or less).

Hope this sheds some light on the mystery of PVCs. Let me know if you have any questions!
Posted 2/6/2008 8:40 AM (GMT 0)

Thanks for that Sarita!

I've had mitral valve prolapse for 30 years with extreme symptoms which are mostly controlled with beta blockers.  But in the last two days I've probably thrown about 150 PVC's and even though I KNOW not to get upset, it's almost impossible to stay calm when you feel like the next skipped beat might be the last! 

You are so right about distraction and relaxation (Lord, how I wish those techniques worked as well with the gut problems!).  There is no question in my mind that even 10 seconds of thought devoted to worry about irregular heart beats will substantially increase the number of them that you have!

Thanks for reminding me!

Posted 3/4/2008 7:48 AM (GMT 0)
No problem Gutastrophe, I know that PVCs are very distressing. I am bumping this up for a member of the GERD forum who might benefit from some more info!
Posted 3/4/2008 10:11 PM (GMT 0)
HI New to this site, a couple of months ago i got palpatations for 2 weeks solid morning to night after tablets to slow my heart rate down an ECG and the holter machine the doctor said i had a slight fast heart beat which is noting to worry about but he was going to send me to see a Cardiologist which was grand i was glad he was refering me to to be sure but since then i have been getting a strange sensation in my chest i def. would nt call it pain infact its very hard to describe at one stage i would say it was like an extra something in my chest now i know that sounds mad but i really cant describe it. I seem to only get it while lying down whether thats because i am relaxed or what i dont know but it is starting to worry me i am thinking maybe i have angina or something.

Do you have any comments for me or do i sound a bit mad!!!!
Posted 3/4/2008 10:57 PM (GMT 0)
Hi tlight, no, you don't sound mad :) It's good that you are going to see a cardiologist, hopefully they can check you out and give you some answers and an idea of what approach to take for your rapid heart beat. The sensation you describe sounds like an irregular beat and perhaps a PVC, like I've written about in this post, but you can't tell for sure unless you have an EKG or other testing done. Angina is severe chest pain caused by lack of oxygenated blood reaching the tissues and occurs when someone has narrowed arteries. When do you see the cardiologist?
Posted 3/4/2008 11:16 PM (GMT 0)
I dont see him until Nov. which is quiet some time away but the hospital said if i phone each week they might have a cancelation so fingers crossed. It def. isnt angina then as i really dont have that kind of pain maybe it is anxiety but i have to say it has helped me quiet a lot reading other peoples messages its kinda put me at ease a bit even though i would really like this to stop altogether. Thanks for your reply
Posted 3/4/2008 11:51 PM (GMT 0)
November, WOW, that is a long way away. If you are feeling really miserable you could always go to the ER where they could do an EKG. In young, otherwise healthy people these palpitations have no real pathological basis (that is, they are not caused by disease) and they are certainly exacerbated by anxiety. If they are bad enough some doctors will put you on a medication called a beta-blocker, which slows down the heart rate and tends to help keep the palpitations at bay. You might try staying away from caffeine, alcohol, nicotine, and keep up with an exercise program that you are comfortable with. All of those should help to minimize the palpitations. Keep us updated and let us know if you have more questions!
Posted 3/5/2008 9:11 AM (GMT 0)
Hi Sarita, thanks for your reply i do love a couple of cups of coffee a day especially first thing in the morning but i know i should steer clear, fairly good with the exercise since the palpitations went back to gym so at least thats one good thing.  I will keep you posted with what the doctors say.
Posted 4/2/2008 12:22 PM (GMT 0)

Thanks so much for all the information.  It is very helpful.  BUT........What makes most pvc's benign if an electrical study isn't done? I started noticing PVC's about a month ago . I got an ekg, halter, will be gettung a stress test and echo.  Assuming that all results are negative I then ask why am I getting them..............My TSH was low, outside the range and I cut back on my medication about a week ago, but still no improvement (maybe it takes longer)  Could this cause them.....My concern is that they could turn into Vtack or Vfib at any given time even if my  tests come out okay............Am I getting carried away about my concerns?    Am I over exaggerating the possible results of PVC's.  Appreciate all responses...Thanks

Posted 4/3/2008 3:17 AM (GMT 0)
anti, absolutely, having a low TSH can lead to palpitations. A low TSH (below the normal range) means that the thyroid is pumping out a lot of hormones, and thyroid hormones control pretty much everything in your body to a certain extent, including the heart. High thyroid output = increased heart rate and palpitations. Are you hypothyroid and taking synthetic thyroid replacement? You need to speak to your physician about this ASAP. It might take a while longer for the med decrease to have an effect, but in the meantime you should at least ask your doctor about taking a beta-blocker temporarily...this might help your palpitations.
Posted 4/4/2008 12:11 AM (GMT 0)
Thanks for your reply.  Yes, I am taking thyroid medication due to being diagnosed with hypo many, many years ago.  Its so funny that I was on the same dose all these years and now all of a sudden its too much medication,  But that really is whats happening as my blood work shows it.  I will be going for my stress test/echo in a couple of days and I'll talk to my doctor about medication for the PVC's.  Today, they finally quieted down and I'm not having as many.  Maybe my med decrease is kicking in............Too bad I got PVC's  because I felt terrific with a extra low TSH, but I guess my body is talking to me.........
Posted 4/4/2008 6:57 AM (GMT 0)

Sarita, I need some support and consolation/advice.  Six weeks ago, I was having the pvc's for about two weeks.  I increased my nadolol for about three days.  Then I decreased again back to my original dose (doc's supervision).  They stopped just as suddenly as they started.  Three days ago, they came back with a vengence.  I can't tell you how DISTRAUGHT I am over this.  Doc did an EKG last visit but of course I did not have even one stinking arrhythmia during the test.  He KNOWS my condition well, as he's been treating me for 18 years.  BUT, I am still convinced I am minutes away from a cardiac arrest.  It just does not seem possible for the heart to beat so erratically 500 to 600 times a day.  How can that possibly be benign?

I am considering requesting an ultrasound.  Since I've been dx with MVP, I was hoping this test could show whether the regurgitation has worsened.  Is this the right test to have or should I ask for something else?  Also, while I hate that I have to factor this in, I've been laid off and cosequently have no insurance right now.  I'd rather not sink thousands of dollars into an unnecessary test.  What would you suggest?

You know, I've dealth with the gut and the psoriasis and the headaches and all the other ridiculous maladies for decades but nothing, and I mean NOTHING freaks me out like this.  It's utterly terrifying.  HELP!

Posted 4/4/2008 8:03 AM (GMT 0)
Oh, gutsy, I know how scary this is...so let me understand, you've been taking nadolol, worked like a charm, then started decreasing and now you are having them again? Do you notice when the palpitations come on, where you feel them, how long they last, how frequently they occur, does anything make them feel better or worse (exercise, lying down, etc.?), and how much discomfort are they giving you (say on a scale from 1-10)? When was the last time you had a "work-up" (i.e., an EKG and echocardiogram)?

It might be good to get another echocardiogram, but those are expensive. You'd have to talk to your doctor - if he thinks it's necessary, he might cut the cost for you if that's in his power to do so. Or they have payment plans...I'm a big fan of those. Even though they suck me drive!

When I was hospitalized last time I had hypovolemia (volume depletion) from all of my diarrhea, which led to a burst of arrhythmias, orthostatic hypotension (rapidly dropping blood pressure upon standing), dizziness, near-syncope...it was awful! After an infusion with NaCl solution and some potassium, I was much better. I have chronic hypokalemia which can lead to these symptoms. UGH is right.
Posted 4/4/2008 4:08 PM (GMT 0)

Sarita, I am thanking God for you!  Even your posts are calming!

I didn't start decreasing the nadolol initially.  I've been on 120mg for years and years.  Controlled the arrhythmia like a charm. Out of the blue, they started about 7 weeks ago.  Went to doc, had an EKG, during which not ONE expressed itself!  As I said, my doc has been treating me for this for 18 years so I know he is familiar with the types of PVC's I have.  But still, I was disgusted that I couldn't coax even one during the test.  I am always sure that when they return after long remissions, that they must be the "serious" life-threatening kind.  He listened to my heart, of course, and said everything sounded and looked normal and not to worry.  He advised that I increase my dose by 40 mgs.  I did that for about 3 days, felt worse.  Decreased back to 120 again and within 5 days, they were gone four about 3 weeks.  JOY!  RELIEF!  LIFE RETURNS TO NORMAL!  And then, wallop - they are back and even worse than before.  Do I feel them?  You betcha!  It's like there is a tiny man inside my chest with a hammer!  Yesterday, I estimated about 30 per hour.  They seem to diminish when I am lying down, but not always.  Sometimes they are isolated singles, sometimes they come in pairs or triplets.  On a scale of 1-10 I would say a 9.  It's not at all like the docs sometimes describe when they say PVC's are not discernable.  Believe me when I say I FEEL every single one.  I have a knee-jerk reaction of heavy, deep breathing when they come on and I'm not sure if this helps or hurts.  Sort of the panic attack response where you are almost on the verge of hyperventilating.  It's exhausting.  I was so wiped out last night I felt like I had run a marathon.

I decreased my caffeine intake to a half cup a day, although I have been drinking de-caf during the day.   I haven't had an echo in years and years, probably 10.  It might be worth the expense though, if the results were good and put my mind at ease.  I have no doubt that my frantic responses are causing them to worsen. 

My recent blood work showed iron depletion, just shy of full blown anemia.  Could this be a contributing factor?  As you know, with the IBS C, iron would probably KILL me but I am actually willing to consider taking it if it would knock these bad boys out.

Thank you SOOOO much for your help! 

Posted 4/4/2008 4:42 PM (GMT 0)
No problem, guts! Glad I can help!

I don't think that the iron deficiency would lead to palpitations in itself. However, do you know why your iron levels are low? I wonder about that. Did they do a serum ferritin test for you? That is the best measure of iron stores in the body and is helpful when someone is borderline anemic. If there's a good reason for the near-anemia (which you should get checked every month or so, by the way, to make sure you aren't getting worse), there may be something contributing to your increased PVCs/PACs.

When you say you felt worse on the higher dose of nadolol, do you mean you had more palpitations, or some sort of side effects?

30 an hour is annoying as heck but not necessarily dangerous (I know it doesn't feel that way). That time I went into the hospital I had 30 per minute and thought I was going to jump out the window if it continued!
Posted 4/5/2008 6:57 AM (GMT 0)

Wow!  Thirty per minute!  I think I'd stroke out just from the anxiety!  My Sarita, is there anything you haven't been through?

The increased dose of nadolol seemed to increase the palps but you know, it's so hard to tell.  It could have just been my anxiety.  I only took the larger dose for three days so I just can't assume that is what it was.  And the fact that they stopped three days after I went back to my regular dose could also just be coincidence.  Aside from the direct connection between caffeine and palps, I don't know if they can really isolate a reason why they suddenly come on.

Doc just did a regular blood test so whatever that includes is what showed the iron deficiency.  I always assumed it was diet related BUT it might be possible (you tell me) that the large amount of aspirin I take for chronic headache, which I think contributes to the tsunami like menstrual flow I have each month, might have something to do with it?  Don't know.  As I've mentioned on the IBS boards, I only eat one meal a day because of the spasm and pain.  Hard to pack one meal with enough iron, I guess.  Also, my cholesterol is sky high.  These are the only things that have changed in the last few years.

I have increased the nadolol again the last two days.  I feel a bit better today so I'll keep it at 140 for a few more days and pray they cease. 

Your thoughts?

Posted 4/5/2008 7:24 AM (GMT 0)
Aspirin could, theoretically, be contributing to your near-anemia because it can cause gastrointestinal bleeding. The way to check if that's happening is to get a fecal occult blood test. If that is negative, you could rule out the possibility that aspirin is the cause. More likely your low hemoglobin is caused by a combination of your diet and your monthly "tsunami" (I like that analogy, by the way!). Are you on any birth control? That usually helps shorten Aunt Flo's stay :) That is rotten that you can only eat one meal a day. What about drinking an Ensure or something for breakfast? Do you think your gut could handle that?

This might sound weird, but once when I was having a particularly bad run of PVCs I called my cardiologist at the time and he suggested I go for a run. I did, and the palpitations went away. The reason for this is that boosting the heart rate for a sustained period of time (like 15 minutes or so) can sort of "re-set" the heart beat. Sometimes now I will run up and down the stairs for a bit and that helps frequently. So if you've been given the OK to exercise, you might try that. Sometimes I also do yoga to try to calm down and get my mind off them. I think that is the key - to preoccupy yourself with something so that you're not thinking about them.

One other thing that might help is to try coughing really hard. Also sounds weird but has sort of the same effect as exercise. I didn't find that to be a particularly helpful solution in my case, but evidently it does help some people.

I hope you have a really good internist who can help you with all this. There's a lot of pieces to fit together and it's just distressing to hear that you are suffering when there's probably something that can be done to help you. Even trying a new beta-blocker might be a good idea. I take atenolol and it works like a charm. When's your next doctor's appointment?
Posted 4/5/2008 5:40 PM (GMT 0)

Once again, GOD BLESS YOU and your generosity and patience! 

It's ironic that you suggested a "run".  You made this recommendation earlier on this thread and I did file it away.  The last time I had the PVC's (about 14 years ago), I decided to take matters into my own hands and I started walking a half mile every day on my lunch break.  I made sure it was a brisk walk to get my heart rate up and within 2 weeks, the palps had stopped.  It's a great suggestion.  I have to get over my extreme fear that exercising is going to cause a heart attack (because of the palps).  Time to use the logical side of my brain!

As for changing meds - I've been considering this.  The last time I had the palps, doc switched me from Inderal to Nadolol and that made a huge difference.  I was thinking about atenolol just the other night.  I may call him next week and make this suggestion.

I've never taken the birth control pill.  My menses is as "natural" as it was when it first arrived, at the age of 12!  Always been a ultra-super tampon gal!  Since I am peri-menopausal, I'm not going to start messing with things now!

Would gastro bleeding show up on a colonoscopy?  Just had one about two years ago.  Got the all clear.  Don't have any rectal bleeding except for the occasional fissure rupture.

I LOVE my doc.  Been with him for 17 years.  He's extremely intuitive and has no problem with just making a phone call to quell my anxiety.  I'm confident that if he believed there was a more serious problem here, he would refer me to a specialist. 

And of course, the suggestion of distraction is always a good one.  Even with the IBS, I have found that if I am preoccupied with something other than my own discomfort, I do much better.

Thanks again!

Posted 4/5/2008 7:47 PM (GMT 0)
Thank you for your compliments, guts!

Yes, I can see how you might be nervous about jumping into exercise when your heart is doing flip-flops...it seems counterintuitive. But if you've gotten a cardiac work-up before and have been cleared for exercise, there is no reason to think you will suddenly develop a heart attack. It will not only probably help your palpitations, but exercise has been shown to be as (if not more) effective than anti-depressant medications in relieving symptoms of anxiety and depression, and I can pretty much guarantee that you will feel better on some level after a brisk work out! Plus, you get the added bonus of doing something to actually protect your heart in the long-run.

GI bleeding wouldn't necessarily show up in a colonoscopy. Aspirin can wear away the stomach lining after a while and so the bleeding would be coming from the stomach, while the colon would look fine. The fecal occult blood test would show if there's any "hidden" bleeding. It's really easy, just a swab on a card, and the results are instantaneous. Might be something to ask your doctor about (if he's even concerned about your low-ish iron levels).

I'm glad you like your doctor so much. That is invaluable! Hang in there and be strong - you'll stop those palpitations in their tracks soon enough!
Posted 4/6/2008 7:16 AM (GMT 0)

Today was better, although I'm not palp free yet!  Gonna continue with the 140mg for a bit and see if that does that trick.  If they don't stop completely, I might check with the doc about switching to another beta-blocker.

I've no doubt that our conversation here has contributed to their decrease.  I've felt a lot calmer since we've been chatting.  I've also noticed that when I don't get stuck in that anxious, deep breathing/semi hyperventilation syndrome, they seem to diminish.  Yes, often it just takes a trustworthy friend or doc (in this case, you are currently one and will soon be the other) to help alleviate the anxiety.

Doc doesn't seem worried about the iron situation.  He described it like this:  There is wood in the fire but none in the woodshed.  I've been making a real effort to increase my intake of iron rich foods.  Unfortunately, with the high cholesterol, I've had to severely cut back on my meat intake.  HUGE bummer.

THANK YOU THANK YOU THANK YOU THANK YOU THANK YOU THANK YOU THANK YOU!!!

Posted 4/6/2008 10:33 AM (GMT 0)
I know how you feel - sometimes I just need someone to hear me out when I'm feeling cruddy and things seem more tolerable then. I'm glad we could have this conversation for that reason for you. We can keep it going as long as you like. I think you have some good insight about yourself and that surely helps too. Hopefully I'll have lots of patients like you when I'm in practice!

It is 3:30 a.m. and I'm up for a while. Sometimes it seems my body knows when it needs "quiet time" - to think, to study, to listen to silence - and I really like it. At least when I'm free to sleep in later! I know I always moan and groan about being a student but it's been pretty flexible lately and I have to say, I do have more time now to just sort of chill out when I need to.

I've never had high cholesterol but I do take an Omega 3-6-9 supplement, which has been shown to raise HDL ("good" cholesterol) levels; maybe you should try one. They apparently have some anti-inflammatory properties as well, although I don't have any stacks of papers hailing this fact or anything.

I'm glad your doctor doesn't seem worried about your iron; just keep your eye on it and I'm sure your body will naturally find the right course of action.

Cheers, my friend!
Posted 4/6/2008 4:44 PM (GMT 0)

Sarita, I would never classify you as a complainer.  On the contrary, you are usually comforting everyone else (unless you have a life-threatening experience!). 

I'm a bit of a night owl myself.  Last night, at 2am, I was reflecting on the events of 2008 so far (prior to the onset of the palps).  It goes something like this:

  • Dad dx. with Vascular Dementia
  • Mom showing signs of beginning stage Alzheimers
  • I am laid off from work
  • Finances in shambles
  • My 20 year old kitty dies
  • My big sis is dx with Leukemia

Is it any wonder my heart is doing somersaults in my chest?

Posted 4/13/2008 5:00 AM (GMT 0)
Sarita,

Thanks for the comforting post! I've had PVC's, NSVT, and IST for 20 years now, mine started while I was in pred-med (quit after MCAT's) and I still love to hear how benign they really are, in the presence of a healthy heart of course.

I recently (6 months ago) came out of a 13 month cycle of 10,000 to 25,000 PVC's daily and just wanted to hear your thoughts on Magnesium.
I've researched alot during the last year (alot of the stuff came from Europe), and personally, I swear by the stuff when it comes to PVC's and certain arrhythmia's now.
My problem is that my serum potassium always ran around 2.9 to 3.2 mEq/L (suspected ion/voltage gated channel deficiency) and my magnesium was running around 1.1 mg/dL. (normal values 1.6 to 2.6) even with a very healthy diet. (I also went and had an RCM which was low). After talking with my Cardio, we agreed on increasing my supplemental mag. to around 600 mgs a day and my PVC's all but went away (occasional blip) within 6 weeks. I also increased my daily potassium through diet. After a few months, I started slacking on the mag. and now my PVC's are back.
Two weeks ago my potassium was at 3.6 mEq/L, I'd like to see how I feel at 4.0, and my mag levels were up to 1.6 mg/dL., right on the border.
I just started on the liquid mag again and am considering injections.
Have you discussed magnesium in class yet? 20 years ago while I was going thru pre-med they barely touched on the subject of magnesium for the heart...are the studies and doctors finally coming around in general concerning arrhythmia's and mag? Or is magnesium still thought of as "questionable and unproven" for PVC's?

Again, thanks for the comforting post! I can't hear it enough!

Jewels
Posted 4/13/2008 5:37 AM (GMT 0)
Jewels,
Magnesium definitely has effects on cardiovascular health and rhythm, in that it affects the calcium flow in the heart and affects the sodium/potassium ATPase (a "gateway" for sodium and potassium to flow between the outside and inside of a cell). Some people with PVCs have improvement with magnesium supplements. I wonder about the "suspected ion/voltage gated channel deficiency" you mentioned. It's an extremely complex process and I wonder how they can tell if this is contributing to your arrhythmias. Do you see a cardiologist? Or an electrophysiologist? If you have a lot of symptomatic PVCs that have not improved with decreased caffeine/alcohol/nicotine intake, in the absence of any other known "physiologic" abnormalities, maybe you should talk to your doctor about trying a beta-blocker. I'm sure this avenue has been considered and if you have normal-to-low blood pressure they may shy away from this treatment, as beta-blockers will lower your blood pressure...but it's always worth a shot if you haven't had success with other treatments.

You were pre-med and quit after the MCAT? Jeez, you got pretty far...most people I know who were "pre-med" don't even know what the MCAT is! I had a pretty mediocre score but am still hanging in there in med school :)

I hope you are doing OK, you sound very persistent and level-headed. I know how annoying these arrhythmias can be. When I have a lot of them I am barely functional.
Posted 4/13/2008 5:41 AM (GMT 0)
Gutastrophe,
I can't believe what you have gone through the past few months. Dementia and Alzheimer's disease are incredibly difficult, just painful, for families. Your sister has leukemia - what kind? My goodness, as if that weren't enough. The loss of a pet, and sick pets, make my heart hurt. My childhood kitty (he is 18 years old) is nearing the end, and every time I think about it (like now) I just tear up...

It's definitely no wonder you've been having some extra "issues." I hear you. Although I know it's rare to have people really hear you!

Girl, have you talked to anyone in person about all of this? I mean, someone you really trust?
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