Quantification of Electromechanical Coupling to Prevent Inappropriate Implantable Cardioverter-Defibrillator Shocks

Figures

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  Figure 1. Data Sampling Windows (Left) For each VF episode, overlapping 6-s time windows were analyzed. (The same number of sinus rhythm windows were analyzed from immediately before VF induction.) (Right) For each window, a perfusion value was calculated (green circles for sinus rhythm, red triangles for VF). VF = ventricular fibrillation.

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  Figure 2. Discriminative Capability of Laser Doppler to Differentiate Sinus Rhythm From Ventricular Fibrillation Perfusion values are shown as green circles (sinus rhythm windows) and red triangles (VF windows). (A) The Electro-Mechanical coupling method shows 100% discrimination for each patient between the 2 states. No sinus rhythm window of any patient scored <2. (B) Running Mean method, failing to discriminate in 12 patients. (C) Oscillatory Height method, failing in 26 patients.

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  Figure 3. Discriminative Ability of the Running Mean, Oscillatory Height, and Electromechanical Coupling Methods (A) Horizontal gray dotted lines indicate thresholds for each analytical mode, chosen to maximize the sum of sensitivity and specificity. The Running Mean and Oscillatory Height had substantial overlap between sinus rhythm and ventricular fibrillation (VF) perfusion data. (B) Receiver-operating characteristic (ROC) curves for Running Mean, Oscillatory Height and Electro-Mechanical coupling analytical methods. The area under the curves are 0.91, 0.86, and 1.00, respectively.

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  Central Illustration. The Electro-Mechanical Coupling Approach in Situations Where Inappropriate Therapies May Otherwise Result Sinus Rhythm: Gating the laser Doppler signal by the R-R interval from the right ventricular (RV) lead shows a satisfactory consensus perfusion value. A similar situation would occur in other well tolerated rhythm disturbances. RV lead fracture: Gating the laser Doppler signal by the R-R interval from the fractured RV lead shows an unsatisfactory perfusion value. When gating is performed by an alternate electrical signal (atrial lead in this example) a satisfactory consensus perfusion value is seen. EGM oversensing: Gating the laser Doppler signal by the R-R interval from the RV lead shows an unsatisfactory perfusion value. Appropriate gating by the algorithm (which simultaneously tests multiple hypotheses as to which are the true R waves) shows a satisfactory consensus perfusion value. True VF: Gating the laser Doppler signal by R-R intervals detected by the ICD lead, alternate electrical signal and by the multiple hypothesis method each time reveals no satisfactory perfusion. ECG = electrocardiogram; EGM = electrogram; ICD = implantable cardioverter-defibrillator; VF =…