Patient, recipient of a Abbott Current DR ICD was hospitalized for palpitations and an ICD shock.
Main programmed parameters
Tracing
The device can be programmed for a maximal duration of arrhythmia, at the end of which therapy is delivered even if the tachycardia has been classified as SVT; this eliminates the risk of an untreated VT that has not been properly diagnosed by the device, at the risk of delivering inappropriate therapy for an episode of SVT that was accurately diagnosed as in this patient. This represents a “safety”, which increases the sensitivity of the discrimination algorithm, at the cost of some specificity. The programming of this kind of parameter is an expression of limited trust in the ability of the device to discriminate flawlessly the tachyarrhythmias.
It is our practice to usually deactivate these clocks, in order to avoid inappropriate therapies delivered for episodes of accurately detected, sustained SVT.
Episode initially diagnosed as SVT in the V=A arm. The discriminators were discordant, as morphology indicated SVT while onset indicated VT. Hence, SVT was diagnosed and no therapy was initially delivered (all parameters required for VT). Then VT diagnosed (SVT timeout) despite the persistence of one discriminator in favor of SVT. 2 ATP and 1 shock are then delivered.
