atrial/ventircular or dual chamber pacing

[mariete]

  Dear Doctors!
  First of all thanks for all the good work you are doing and the great help you provided me earlier!
  I have a question that is bothering me... I had a pacemaker check up today to see if there were signals of a-fib again, which could have caused my recent stroke. There were not many significant events during the previous 95 days. Only a couple of mode switches as well as 450 PMT interventions. Now my questions are as follows:
  1.
  I now have a DDDR pacer, set at lower rate 60 bpm and upper 130 bpm. AV interval 280 ms. Now they seems to think that it owuld be an idea to change the programming to atrial pacing only, to prevent the PMT's.... Mind you: 65% of the pacing was ventricular, approx 30% dual and 0.5% sensing only. So... I wonder who is a nutcase here.... How do they think to get me off the ventricular pacing mode?? They don't really know what to do obviously. I am getting a bit tired, since I wanted my datareports to check by Medtronic, and now the graphs are missing from my file.... What a coincidence...
  2.
  Is a PMT always a tachycardia mediated by the pacemaker? Or can this also just be a "normal" tachycardia?
  3.
  I asked earlier if an a-fib is also possible at a lower rate, which you confirmed. Today I asked the pm technician the same thing and he told me that a-fib was only possible at rates around 200.... I actually trust you more, but what I wanted to know: are only very short episodes of a-fib enough to form clots within the hearts causing strokes?
  4.
  How long can bloodclots stay within the heart before they "go" to the brains? I mean..is it theoretically possible that clots were formed weeks ago and only caused trouble now?
  Thanks very much for your reply and help. I hope that it makes sense to you... It is really worrying me and I get sick of all the incompetent doctors here in the Netherlands.
  Thanks, Mariette

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Dear Mariette
I do not know your doctors personally, but I must disagree with your statement regarding doctors in the Netherlands. The ones I know are all excellent cardiologists.
I cannot comment on the specifics of your pacemaker programming. As far as the need for ventricular pacing, it depends on your underlying heart rate and the reason the pacemaker was implanted. Pacemaker mediated tachycardias are often treated by increasing the PVARP or decreasing the AV interval.
PMT is by definition a pacemaker mediated tachycardia. However, other tachycardias can be present even if a patient has a pacemaker.
Afib can occur at a rate of 200 or more, but it definitely can occur at much lower rates.
Short episodes of afib can cause clot formation, but his is statistically unlikely. The longer you are in afib without being on a blood thinner, the more likely it is that you will form a clot. Usually, clots do not form unless you have been in afib over 2 days. If the clot is going to cause a stroke, it almost always will do so while you are in afib, or shortly after you convert to normal, not weeks later.
I hope this is useful. I wish you the best of luck. Feel free to write back.
If you would like to set up an appointment with one of our cardiologists here at the Cleveland Clinic please feel free to call 1-800-CCF-CARE.
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