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Heart & Cardiology/Low co2 Pacemaker dependent


Dr. Ahmed,
Thank you for your time.  I am a 47 yr old woman who is pacemaker dependent.  Since the end of March I have had episodes of feeling like I can't get enough air, fainting and dizziness.  Last week at work, after walking up stares I just couldn't breath and I collapsed, breathing heavy, shaking, nausea, blacking out.  911 was called and I was taken to the hospital.  I was told my potassium was low and my CO2 was 17.  I was given potassium and bags of fluid and sent home.
Yesterday, I went to my Cardiologist to get clearance to return to work.  When they checked my pacemaker they determined my pacer went into safety mode on March 21st.  Exactly when I began feeling poorly.  I was shocked as was my Dr.  At my last check in Feb It said I had a year left.  
Here are my questions...
I was told safety mode lasts for 3 months then the pacer stops working.  I have no underlying rhythm, so this is scary to me.  My 3 months end June 21st.  I am scheduled for a replacement on June 19th.

Do you think this is cutting it a little close to the end date? Also
Could my the minimal function of my pacer have caused the episode for which I went to the hospital?  The low CO2 etc?
Thank you again for considering my questions!  Any thoughts are appreciated.


The safety mode can last longer than 3 months, also your cardiologist will typically bring you in for a change far before any time of concern, particularly if pacemaker dependent. In terms of the symptoms a lot depends on the type and make of the pacemaker inserted. Some pacemakers will pace in a different mode to save battery when they reach end of life, and this can lead to symptoms. Im not sure thats related to the symptoms that led you to go to hospital however. I would discuss your symptoms with the cardiologist and let them know that the safety mode corresponded with the symptoms and you are wondering if this is related to the mode switch, if so then you may want to address this earlier so you feel better.

Hope that was helpful,  

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Mustafa Ahmed MD


Cardiology, Interventional Cardiology, Cardiac Surgery, Hypertension, Pulmonary Embolism, Structural and Valve Disease


Board Certification Internal Medicine and Cardiology Interventional and Structural Cardiology


Multiple Publications In High Quality Peer Reviewed Journals. Internationally Recognized.

MD from The Royal Victoria University of Manchester, England Medicine, Cardiology, Interventional Cardiology, Research Training - University of Alabama

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