Echocardiographic assessment of epicardial defibrillator patch electrodes

We performed a blinded controlled analysis of transthoracic echocardiograms on 18 patients before and after epicardial defibrillator patch electrode placement to determine the accuracy of echocardiography in identifying defibrillator patches and to determine possible echocardiographic findings that may correlate with defibrillator function or perioperative complications. The sensitivity of two-dimensional echocardiography in detecting defibrillator electrodes was 72% by one observer and 39% by a second observer. Corresponding specificities were 67% and 83%, respectively. The discordance rate was 27%. The echocardiographic finding of patch buckling was not observed and echocardiographic estimates of the distance from patch to epicardium did not correlate with defibrillator threshold at the time of surgery. We conclude that: echocardiography is only moderately sensitive and specific in identifying epicardial defibrillator electrodes; significant interobserver variability does exist; and echocardiography therefore cannot be used reliably to assess for pericardial changes or possible complications of patch electrode placement.