Symptomatic Intermittent 2nd Degree Heart Block

I posted before but wasn't asked for $,please forgive if this is just a repeat
54yo female, h/o HTN (tenormin 50mg QD), IBS,GERD,Goiter (labs wnl).  2003 had symptomatic slow,arrythmia w chest tightness,sob,(never dizzy) after position change. To ER, Dx 2nd degree AV block,RBBB, HR 38-48.Admitted. Tenormin DC'd. After 3 days in hosp w bradycardia ,HR to170-180(prob d/t no tenormin) SVT narrow QRS. Cardio thought possTachy-Brady Syndrome. Had EP done rhythm could not be reproduced .Dx IST, High grade physiological?AV Block -etiology unsure-put back on tenormin-assured not life-threateninng-(to come back if occurred freq).  30 day event monitor=occ atrial tach, pac/pvc's, 1 episode svt. Over the yrs had 4 similar episodes , to ER usually K+ 2.8, many PAC's and rate again 40-50's. Tx w K+, sent home all back to normal). Loss of K thought d/t IBS. Well, happened again but worse, now live in Fl, to ER, same scenario except K+ OK. Sent home b/c after hrs in ER the EKG was OK and rhythm reg again. Continues to happen sporadically now, New Cardio says 2 things going on at diff times 2nd degreeAV block and then sometimes PAC's causing slow rate and symptoms . I am scheduled for 2nd EP tomorrow, but I am scared .  I'm not athletic, so how can I get physiologic block(which has been speculated) What could be happening here? Echo in 2007 normal. I'm fearful of ablations b/c I hear they can increase sx and b/c I don't really know these Docs here.  May I have your opinion please? P.S. Tenormin usually helps with the symptoms.

[Michael J. McWilliams, M.D.]

I read your last post, but there are few things that you say here that clear it up.

Physiologic block occurs when there is a premature beat in the upper chamber (atria) that comes when the AV node is not ready to conduct.  The sinus node is reset by the PAC and has to wait to be ready again.  Say your heart rate is 60 beats per minute - one beat per second.  Then you have a premature atrial beat that occurs at 0.5 seconds and it blocks the AV node.  Your sinus node would not be ready to beat again for another second.  So now you have one beat in 2.5 seconds.  If you have one premature beat for every normal beat, now you have a functional rate of 24 beats per minute.  If you have just a few PACs with block per minute, you can see how this could add up to decrease your effective heart rate.

Mobitz I or second degree type 2 heart block can work in a similar way to decrease your effective heart rate -- it depends on how many beats are in the drop cycle and how symptomatic you are during the pause.

There must be something else going on though because neither of these two events is an indication for an EP study.

If you think the procedure is not indicated, get a second opinion.  I find academic centers a great place for second opinions because most academic centers are salaried and most private practiced make money from procedures.  In academic there is no motivation for unnecessary procedures.

I hope this helps.  Thanks for posting.

[worriwart]

When I lived in Akron Ohio I would have gone to CCF, do you know of any reputable academic areas here in SW Florida? I truely am out of my element here.  And I sincerely thank you for your input into my problem.

[Michael J. McWilliams, M.D.]

Dr. H A. Hazlitt, MD
455 Pinellas Street
Clearwater, Florida 33756

Dr. Hazlitt is in private practice, is very well trained and a very honest person.  If you are near Clearwater, it might be worth a second opinion.