Hi sktrans!
Your source text involves an "interrogation" of a pacemaker.
The pacemaker is in the patient and it is being checked out wirelessly.
The pacemaker has a memory which is being read. It reports such things as what percentage of the ventricular beats were actually stimulated by the artificial pacemaker (Vp). We use the same term for this reading of the pacemaker memory in French and English - interrogation.

Here is a list of pacemaker parameters which should help you with your other questions: http://www.pacemakerclub.com/public/jpage/1/p/Abbreviations/...