Question: What is pacemaker syndrome, and is it always caused by a pacemaker?
Answer: Well, a pacemaker syndrome is classically thought of as a condition in which a pacemaker is stimulating the lower chambers of the heart and not necessarily the upper chambers of the heart so that activation of the heart starts in the lower chambers and then spreads upward to the upper chambers. So, therefore the normal activation of the heart electrically is reversed. Instead of the upper chambers being activated electrically and then the lower chambers being activated electrically, it goes in the reverse directions so the lower chambers beat before the upper chambers.
And so, the upper chambers beat against closed valves in the heart causing blood to be pushed backwards, causing a variety of things to happen: a sensation of pounding in the chest, shortness of breath, sometimes dizziness or lightheadedness because of low blood pressure, a sensation of shortness of breath, weakness and fatigue.
Pacemakers in some circumstances can cause this especially for pacemakers that are working simply on the lower chambers of the heart. And defibrillators can cause this in a similar way.
Other rhythm disturbances can exist that can do the same thing as would occur with a pacemaker. So, pacemaker syndrome is also used -- that terminology is used -- for other heart rhythm disturbances in which the lower chambers are activated causing the upper chambers to be activated in the wrong sequence.