0
edits
Dobutamine Stress Echo: Difference between revisions
no edit summary
No edit summary |
No edit summary |
||
| Line 280: | Line 280: | ||
DSE with low- gradient aortic stenosis | DSE with low- gradient aortic stenosis | ||
Low- gradient aortic stenosis is defined as a severe aortic valve stenosis (AVA < 1.0cm | Low- gradient aortic stenosis is defined as a severe aortic valve stenosis (AVA <1.0cm<sup>2</sup>) with a transvalvular pressure gradient ≤30mmHg. A low- gradient aortic stenosis occurs in patients who have LV dysfunction with decreased ejection fraction. The assessment of the AGM in these patients may be overestimated because the calculated AVA is proportional to the displacement. A poorly functioning LV can exert enough pressure to open. Calcified aortic valve sufficient At a fixed, or "true" stenosis in which the stroke volume increases, the gradient across the valve is relatively also increases. In some patients, an increase in stroke volume results for only a limited increase in pressure gradient across the aortic valve. This phenomenon is called a "pseudo stenosis". DSE is a tool to distinguish between a true and a pseudo stenosis stenosis. Distinction | ||
Patients with pseudo- stenosis manifest an increase in the calculated AGM and a decrease in resistance of the valve as a response to an increase of the stroke volume. The reaction is different in patients with severe aortic stenosis true in whom a dobutamine - induced increase in the transvalvular flow, giving an increase in the mean transvalvular gradient, but no change in AGM. | Patients with pseudo- stenosis manifest an increase in the calculated AGM and a decrease in resistance of the valve as a response to an increase of the stroke volume. The reaction is different in patients with severe aortic stenosis true in whom a dobutamine - induced increase in the transvalvular flow, giving an increase in the mean transvalvular gradient, but no change in AGM. | ||
| Line 286: | Line 286: | ||
A DSE study in a low- gradient aortic valve stenosis is given a low -dose dobutamine. That is, they started to get 5μg/kg/min and gradually increased to a maximum 20μg/kg/min. | A DSE study in a low- gradient aortic valve stenosis is given a low -dose dobutamine. That is, they started to get 5μg/kg/min and gradually increased to a maximum 20μg/kg/min. | ||
If there is an increase in stroke volume, an increase in AVA | If there is an increase in stroke volume, an increase in AVA ≥0.3cm<sup>2</sup> and a small change in gradient produced after administration of Dobutamine there is an overestimation of the severity of aortic stenosis (=pseudo stenosis). | ||
A DSE may also demonstrate a severe aortic stenosis with low transvalvular pressure gradient or contractile reserve. Contractile reserve has a predictive value for mortality in surgery of aortic valve replacement. Recent studies have shown that perioperative mortality 5-8 % versus 32 % without contractile reserve in contractile reserve.<cite>2</cite> | A DSE may also demonstrate a severe aortic stenosis with low transvalvular pressure gradient or contractile reserve. Contractile reserve has a predictive value for mortality in surgery of aortic valve replacement. Recent studies have shown that perioperative mortality 5-8% versus 32% without contractile reserve in contractile reserve.<cite>2</cite> | ||
==Indication DSE== | ==Indication DSE== | ||