Mixed aortic valve disease can sometimes occur in aortic stenosis when the heart valve becomes so rigid that it can neither open nor close properly and it becomes a fixed obstruction to the flow of blood. It is effectively stuck half open.

This produces both an increased load for the heart to cope with and also an insult as, after each beat, a proportion of blood then leaks back into the heart.

The load on the heart here is of too much blood (volume) and too much strain (pressure) and heart valve repair may be necessary.