{TAIL ~ The implantable antitachycardia therapy device,17}, wherein the threshold detection means includes means for detecting in which of a plurality of {HEAD ~ rate zones} the heart rate lies 
{ TAIL ~ The implantable antitachycardia therapy device,17 } , wherein the threshold detection means includes means for detecting in which of a plurality of { HEAD ~ rate zones } the heart rate lies
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH