Boston Scientific Advisory

The Boston Scientific advisory is confined to their pacemakers using Minute Ventilation, MV. I will read the email I received from my wonderfully gifted Boston Scientific Tech that has tried to help me for the past year resolve other unrelated issues with MV concerning the Accolade model. His mail was in response to my inquiry to him after hearing about this issue from a Cardiology office, this is his reply.

"The Advisory that we just issued is a phenomenon that is only relevant for patients who are pacemaker dependent or heavily rely on either atrial or ventricular pacing. As you may recall the MV algorithm takes an impedance measurement across the chest every 50ms so that we can calculate the volume of oxygen in the lungs accurately, knowing when you are exerting yourself, increased volume equals exercise. To take this impedance measurement, the pacemaker outputs an electrical stimulus, current, and then measures the subsequent voltage. Because the pacemaker knows that it is putting out this electrical stimulus, it also knows that it shouldn't detect the stimulus as an atrial or ventricular heartbeat. However, if the system has a high impedance for some reason, lead fracture, incomplete connection in the header, etc. the pacemaker is fooled into thinking that this MV electrical stimulus is something that it should detect and pay attention to. If that signal is sensed by the pacemaker, then it will not pace because it believes that the patient heart is beating on its own, we call this pacing "inhibition due to noise over sensing." If this pacing inhibition occurs when the patient needs the pacing to survive or even just to stay upright, this is obviously a bad thing.

"Many Physicians are simply turning off the MV sensor in all of their patients, but some are picking and choosing those patients who may be adversely affected if there is pacing inhibition. The high impedance situation can occur more often when the patient has our pacemaker with either Medtronic or St Jude leads attached." End of quote.

The Cardiology nurse that alerted me to this advisory, again not related to my troubles with MV, indicated that this is a very low percentage probability, but obviously serious when it happens if you are pacemaker dependent.

As a footnote the kind of "high  impedance" they're referring to is not the kind they measure at a pacemaker session, but one would hope it would be detected if it existed.

The Bible on our hearts:

Above all else guard your heart, for everything you do flows from it.

Give me your heart and let your eyes delight in my ways.

Take Delight in the Lord, and He will give you the desires of your heart.

 

 

 

 


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