Monitoring of cardiac activity during application of conducted electrical weapons (CEWs) is difficult because electrical pulses and muscular activity cause excessive interference and "noise", making electrocardiographic interpretation impossible. Even palpating pulses during application of CEWs is difficult or impossible. Invasive monitoring with an arterial line or right heart catheterization is useful in animal models, but is not practical in human subjects. Ultrasound of the heart (echocardiography) during application of CEWs is feasible and provides valuable information about cardiac rate and rhythm. Echocardiography has been used to monitor cardiac activity during CEW application in both animal and human models with very different results.