Q. A patient has been provided with a single chamber pacemaker recently for complete heart block. The pacing mode is set as VVIR. R in VVIR stands for? A. Rate responsive B. Rate controlled C. Rate sensitive D. Rate inhibition Answer: A. Rate responsive Explanation: 1st letter: Chamber paced 2nd letter: Chamber sensed 3rd letter: Action of the pacemaker after sensing a beat 4th letter: Rate responsiveness i.e. demand ventricular pacing is present with response to exercise VVIR means: Ventricle is paced, ventricle is sensed, pacing is inhibited if beat is sensed and rate responsiveness is present in pacemaker i.e. rate of pacing is increased if a physiological need is there e.g. during exercise.
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