pauses and av block

I am 39 yr old male.  I have been running since high school track and have had a resting heart rate in the low 40's even high 30's for as long as I can remember.  For many years I ran 15-20 miles a week but last year I decided to take up marathoning.  I completed my 1st marathon after 6 months of specific training and noticed after the race that I was an increase in skipped beats which my doctor told me were probably PVC's and I shouldn't worry about them.  After running Boston Marathon this spring I decided the frequency of the PVC's was making nervous me and my doctor suggested a holter monitor and, if indicated, an echo-cardiogram.  TheHolter results came in withmultiple PVC's but also, at night my pulse dropped as low as 26 with several pauses, most less than 3 seconds but between 2 and 15 (the data I have is not broken down enough) were between 4 and 5 seconds.  2 holter data plots were provided for these long pauses which shows a single sinus pulse with no beat after it.  I suspect that this only happened 2 times in 24 hrs but definitely less than 15, all in a 1 hr period at night.  My cardiologist flet I may need a pacemaker but referred me to an arrythmea specialist for a 2nd oppinion.  I am also scheduled for an echocardiogram tomorrow.  I would like to be well educated when I talk to the specialist.  I have read that pauses, very low pulse at night, and AV blocks are common in atheletes but I don't know if the type of av block could be a result of good fitness.  In case the level of performance is an indicator, I placed in the top 4% overall in Boston and typically place in the top 1-2% in local races.

[Cleveland Clinic]

Slow heart rate due to sinus bradycardia or even some heart block (type I second degree) while sleeping is common in athletes such as yourself.  this does not warrant a pacemaker unless you are having symptoms.  of course, when you are sleeping you won't be having any symptoms, and since you are able to run marathons without any problems, that really stresses your system and therefore, is very reassuring that your conduction system is normal, further supporting that you should not need a pacer.  

[RunningPartner]

A related discussion, 3rd Degree AV Block in Marathoner was started.