Patients who need temporary pacing following open heart surgery and who are willing to participate receive a phrenic nerve electrode during the operation. Heart function is postoperatively assessed by acoustic cardiography (Audicor, Inovise Medical Inc., Portland, USA) during different forms of pacing (right ventricle, left ventricle, biventricular; AAI, DDD) and with or without phrenic nerve stimulation. Acoustic cardiography simultaneously integrates heart sounds and single-channel electrocardiography input to generate multiple parameters that correlate to established hemodynamic measures. Effects of phrenic nerve stimulation on heart function will be analyzed.
In this study, the investigators sought to determine whether a stimulation of the phrenic nerve affects heart function. Heart function is assessed by acoustic cardiography.