Many . Many things can alter some aspects of echocardiogram result including hemodynamic status, cardiac ischemia, and drugs to name a few but there are many more. Understand that the echocardiogram result is a picture of the heart function/structure at a given time, namely at the time the test is conducted. Although there is the capability to acquire 3 d images now, mostly the images are 2 dimensional and can capture misleading results if a thorough exam is not performed to get a complete picture. There are no "false" results per se just perhaps incomplete and at one point in time which may change at another time.
It . It would be possible. Most often this occurs by an error in placing the leads in the appropriate positions.