Abstract 193: Transthoracic Impedance Patterns During Systole Reveal Changes in Cardiac Hemodynamics Using External Defibrillators
BACKGROUND: This study aims to test the Automated external defibrillators (AED) transthoracic impedance cardiogram (EICG) as a potential sensor for detection of compromised hemodynamics in different arrythmias (atrial fibrillation (AFIB), atrial flutter (AFL), ventricular tachycardia (VT)) vs. sinus rhythm (SR).
METHOD: ECG and ICG recordings via pads in antero-apical position from 106 patients with AFIB, AFL, VT, who received external cardioversion (ECV) with external cardioverter/defibrillator are retrospectively processed. EICG patterns are accumulated to compute EICG measures (maximal EICG velocity (dZ/dt-PEAK), ventricular ejection time (VET), ventricular ejection ratio (VER=VET/ RR interval)), static impedance (Z). Hemodynamical indices are collected: heart rate (HR), HR variability (HRV), systolic and diastolic blood pressure (SYS, DIA).
RESULTS: ANOVA test indicates that EICG measures significantly differ in AFIB, AFL, VT vs. SR (Table 1). Multiple linear regression shows that EICG measures are significantly dependent on hemodynamical indices (HR, HRV, SYS, DIA) with multiple correlation coefficient R=0.49 (VET), 0.54 (dZ/dt-PEAK), p<0.001, whereas Z is not correlated. Linear discriminant analysis (LDA) shows that a combination of dZ/dt-PEAK, VET, VER is able to discriminate either AFIB, or AFL, or VT from SR with respective accuracy of 92.8%, 93.9%, 99.1%.
CONCLUSION: EICG measures are significantly correlated to hemodynamical indices and are altered in AFIB, AFL, VT compared to SR. EICG is a potential sensor for compromised cardiac hemodynamics in AFIB, AFL, VT with a discrimination ability for VT vs. SR of 99.1%, but lower for AFIB and AFL vs. SR (around 93%).
- © 2012 by American Heart Association, Inc.