A "b-notch" on the mitral valve in M-mode is associated with what condition?

The presence of a "b-notch" on the mitral valve in M-mode is indicative of increased left ventricular end diastolic pressure. This characteristic notch represents an abnormal pattern of mitral valve motion during diastole, often seen in conditions where there is impaired filling of the left ventricle. When there is increased left ventricular end diastolic pressure, it creates a more pronounced pressure gradient between the left atrium and the left ventricle during diastole, which can cause the mitral valve leaflets to demonstrate this distinct b-notch pattern.

This finding can be a useful clinical marker for assessing diastolic dysfunction and understanding the hemodynamic status of the left atrium and ventricle. In practice, interpreting the significance of this b-notch helps cardiac sonographers evaluate patients for conditions such as heart failure or other forms of diastolic dysfunction associated with increased pressures.