Answer #58

The correct answer is D: Better at getting on axis dimension measurement of the LV. M mode has higher temporal resolution (1000-3000 Hz compared to up to 60 Hz for 2D echocardiography) and higher or equalent spatial resolution. As such it is better able to tell you about fine movments in flutter valves, such as the diastolic mitral valve fluttering seen in aortic insufficiency. One pitfall of M mode measurement is that they may not be on axis, depending on how the probe is aimed at the LV in the parasternal long axis. This is why 2 D measurements sometimes may be more reliable.