Background: Given that an experienced physician is not always available 24 hours a day, immediately and always available echocardiography is usually impossible in the emergency department (ED) and intensive care unit (ICU). To compensate this limitation, the investigators have investigated that offsite expert guided, inexperienced practitioner-performed ultrasonography could be effectively performed. In this study, the investigators aimed to investigate whether the offsite expert can effectively evaluate the visually estimated ejection fraction (EF) while watching and guiding the echocardiographic procedure of onsite novice examiner using the social network video calling chat.

Methods: sixty patients presenting to the ICU and requiring echocardiography will be included. Sixty novice practitioners without any previous experience of echocardiography will participate. Prior to their procedure, the onsite expert complete the echocardiography in advance and determine the EF using the modified Simpson's method (MSM, Reference value). Then, the novice physicians perform the echocardiography again with the offsite expert's guidance via video call. They obtain parasternal long and short axis view and EF is visually estimated to the nearest 5% (ex. 40%, 45% and etc) by the offsite expert while watching the ultrasound video on the smartphone display. The subjects requiring immediate management due to severe symptoms were excluded in this study. Interobserver variability between the calculated by onsite expert and visually estimated by offsite expert was assessed. The agreement of the visual estimated EF obtained by onsite expert and offsite expert via smartphone was evaluated by linear regression and Bland-Altman plots.

Inclusion Criteria:

• The patients admit to intensive care unit

Exclusion Criteria:

• Hemodynamic unstable patients
• Patients requiring immediate management

Sixty patients who admit to intensive care unit Sixty novice sonographers without any previous experience of echocardiography Two offsite experts who are certified as trained echocardiologist by the Korean Society of Echocardiography One onsite expert who is board certified cardiologist