Also, stimulation at {HEAD ~ a physiological back up frequency} is provided in the event of {TAIL ~ a detected ventricular pause} 
Also , stimulation at { HEAD ~ a physiological back up frequency } is provided in the event of { TAIL ~ a detected ventricular pause }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL