What happens to diastolic blood pressure in severe Aortic stenosis ?
Traditional answer: The diastolic BP remain unchanged. Only systolic BP falls as it is related to LV stroke volume .(What we refer to as systolic decapitation of BP )
Reasoning :Diastolic BP is related to peripheral vascular resistance , hence aortic stenosis has little impact on diastolic BP .
If we assume only the systolic blood pressure is bound to decrease in AS , at one critical point of time* systolic BP should approach the diastolic pressure and pulse pressure should approach zero .This can not happen , hence at that point diastolic pressure will also fall.
*What is that point ?
No one really knows !
In severe aortic stenosis both systolic and diastolic pressure falls , but the fall in systolic BP is more striking .
* Though it is customary for clinicians to discuss them in isolation both systolic and diastolic blood pressure are closely coupled parameters..In the absence of peripheral run off one of the strong determinant of diastolic BP is . . . systolic BP !
1. What happens in combined aortic stenosis and regurgitation ?
In combined AS and AR we get pulsus bisferiens. implying AR will elevate the systolic blood pressure in spite of obstruction.
2.What happens in associated systemic Hypertension and aortic stenosis . (Which is very common combo in elderly )
Since HT will increase the aortic pressure , the LV-Aorta gradient tend to fall.
However ,this does not happen always as if the original cause for HT was dependent more on the stroke volume rather than peripheral mechanisms .
3. Aortic stenosis with aortic atherosclerosis .
A stiff aorta augments the percussion wave amplifying the symbolic BP and blunting the classical anacrotic pulse of AS.
4.What happens to BP during exercise in severe AS ?
Exercise demands raise in systolic BP and temporary reduction in diastolic BP due to peripheral vaso dilatation in exercising muscles.
If a fixed crtical AS does not allow the systolic BP to raise as required , diastolic continue to fall pulse pressure should still become wide .
Excercise testing is a tricky business in AS. Some have attempted it to assess the functional capacity.(Read below)