Medtronic PROTECTA XT DR D314DRG, Clinician Manual

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8.4.5.5 QRS complexes with a low match score
Figure 167. Recorded VT episode showing QRS complexes that do not match the template
8.5 Discriminating sinus tachycardia from VT using the
Onset feature
Patients experiencing sinus tachycardia may exhibit ventricular rates in the VT detection
zone. If sustained, such fast ventricular rates may cause an inappropriate delivery of a
ventricular tachyarrhythmia therapy. Sinus tachycardia can generally be distinguished from
ventricular tachycardia by the speed of the ventricular rate increase. Typically, sinus
tachycardia is characterized by a gradual ventricular rate increase, while ventricular
tachycardia exhibits a sudden ventricular rate increase.
8.5.1 System solution: Onset feature
The Onset feature may help prevent detection of sinus tachycardia as VT by evaluating the
acceleration of the ventricular rate. If the ventricular rate increases gradually, as typically
happens during sinus tachycardia, the device does not classify sensed ventricular events
that occur in the VT detection zone as VT events. If the ventricular rate increases rapidly,
as typically happens during a ventricular tachycardia episode, the device does classify
sensed ventricular events that occur in the VT detection zone as VT events.
Medtronic PROTECTA™ XT DR D314DRG
334 Clinician Manual