Impact of Defibrillation Test Protocol and Test Repetition on the Probability of Meeting Implant Criteria

Abstract

The defibrillation test protocol greatly influences the probability of meeting implant criterion. Therefore, these test protocols should be standardized. The model developed in this study, could be used to further understand their impact and to derive recommendations.

Implantable Cardioverter Defibrillator

“…Simulations based on clinical data demonstrate both that the mean DFT depends on the specific testing method used (shock protocol, initial shock strength, and shock step size) and that the standard deviation of most clinical methods is wide. 6,7 Vulnerability testing is based on the close relationship between the ULV and the minimum shock strength that defibrillates reliably (see Figure 116-3, B). 8 The ULV is the weakest shock at which VF is not induced when delivered at the most vulnerable time point during the vulnerable period of the T wave.…”

“…6,7 Failure of a test shock at greater than or equal to 20 J and the subsequent maximum output rescue shock is sufficient confirmation if detection of VF is rapid. However, if a test shock fails but a maximum output shock succeeds, the test shock should be repeated.…”

Should You Use DFT or ULV to Assess Defibrillation Efficacy?

“…4 D) testing is more reproducible than DFT testing. 1 Whether safety margin or DFT testing is used, there is an inverse relationship between specificity of failing high-DFT patients and sensitivity for passing low-DFT patients, depending on the implant criterion used. Smits and Virag 1 compared the ability of different implant criteria to identify patients with a 90% probability of a successful first shock at the maximum output of a 35-J ICD.…”

“…[1][2][3] The direct, defibrillation method requires one or more sequences of induced ventricular fibrillation (VF) followed by defibrillation shocks. The pattern of success and failure of these shocks is used to estimate either the defibrillation safety margin or the defibrillation threshold (DFT).…”

The Effect of Direct Current Stimulation versus T‐Wave Shock on Defibrillation Threshold Testing

“…During the implantation of ICDs, ventricular fibrillation (VF) is commonly induced to ascertain the detection and the effectiveness of arrhythmia termination by the ICD. Although there are pros and cons regarding defibrillation threshold (DFT) testing, several methods to induce VF at DFT testing are performed . Delivering a shock at a critical time during the T wave (T‐shock) is the conventional approach .…”