A 72-year-old woman had a pacemaker inserted 4 years ago for symptomatic bradycardia because of AV nodal disease. She is clinically feeling well and her ECG shows normal sinus rhythm at a rate of 68/min but no pacemaker spikes. Her pacemaker only functions when the ventricular rate falls below a preset
interval. Which of the following best describes her pacemaker function?
(B) atrial synchronous
© ventricular synchronous
(D) ventricular inhibited
(E) atrial sequential
(D) The ventricular inhibited (VVI) pacemaker functions when the heart rate falls below a preset interval. If a QRS is detected, the pacemaker is inhibited. If a QRS is not sensed, the pacing stimulus is not inhibited and the ventricle is stimulated