Questions on Mobitz I Heart Block

[spade22]

Hi,

I have two questions on Mobitz I heart block I am hoping you can answer:

1) Are there any known triggers for the heart block arrhythmia (in the case where symptoms are intermittent)?  For example, can electrolyte imbalances or low blood sugar bring on symptoms.

2) Can Mobitz I progress into type II or 3rd degree heart block?

thanks!  

[CCFHeartMD16]

With regard to AV block (or atrioventricular block, or electrical conduction delay between the atria [top chamber of the heart] and ventricle [bottom chamber of the heart]) there are several levels:
1st degree - delay in conduction from atria to ventricles.
2nd degree type 1 (Mobitz 1, or Wenckebach) - progressively longer delay in conduction from atria to ventricles until an atrial beat is not conducted, then resets.
2nd degree type 2 (Mobitz 2) - constant time from atria to ventricles until intermittently one atrial beat is not conducted, then resets.
3rd degree (complete heart block) - no atrial conduction reaches the ventricles, so the ventricles are activated from an internal stimulus and go at a different rate than the atria.

Mobitz 1 block can develop from disease, or from natural wear down of the AV node, which is the junction where electricity from the atria flows through then into the ventricle to stimulate. Low blood sugar should not be a cause, though severe electrolyte abnormalities may contribute. If due to a transient process, the block may develop then go away as the patient improves.

Mobitz 1 occurs at a different level (the AV node) than Mobitz 2 or 3rd degree do (below the AV node) and so development of Mobitz 1 does not typically develop into more severe block. However, routine EKG monitoring (once a year, or if concerning symptoms develop such as lightheadedness or syncope, chest pain, shortness of breath) should be done.

[spade22]

THANK YOU so much for your comments - I really appreciate them.

In my case, I typically experience symptoms occasionally but have noticed there are periods when the symptoms occur a lot more frequently, and the "runs" are much longer.  Its interesting to know that electrolyte abnormalities "may" contribute to this and I have noticed symptoms seem much worse in summer.

My situation is a little more complicated in that I have a clinical diagnosis of LQTS (genetic tests in progress) and bradycardia is one of the known triggers of LQTS events so even though Mobitz I is typically not a harmful condition, there is a possibility it may trigger LQTS-events in me.  I will bring this up with my EP when I see her next.