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Figure 1. Dobutamine echo evaluation in low-gradient aortic stenosis. At baseline (LVOT in panelA and aortic valve in B ), calculated AVA was 0.8 cm2, with MG of 29 mmHg. During peak dobutamine dose (LVOT in panel C and aortic valve in D ), AVA remains severe (real severe AS). EF was 28% at baseline and improved to 40% during dobutamine stress (LV contractile reserve). The dobutamine protocol is started at 5 mg/kg/min and increased by 5 mg/kg/min every 3 min to a maximum dose of 20 mg/kg/min. Contractile reserve is defined as an increase in 20% from baseline in LV function (EF or stroke volume). During maximum stress, AVA should be higher than 1.0 cm
2 in order to be considered 'pseudoaortic stenosis'. AS: Aortic stenosis; AVA: Aortic valve area; EF: Ejection fraction; LV: Left ventricularLVOT: Left-ventricular outflow tract; MG: Mean gradient.
(Figure omitted. See article PDF.)
Figure 2. Decision making in low gradient aortic stenosis. AS severity and LV contractile reserve assessed by dobutamine echocardiography will guide the decision-making process. LV contractile reserve is defined as an increase in 20% of the baseline LV function during dobutamine infusion, assessed by EF or stroke volume. For patients with real severe stenosis, AVR is indicated, unless there is no LV contractile reserve and predictors of poor postoperative outcome (mean gradient < 20 mmHg or CABG) are present. In this case, prognosis is extremely poor and then surgery will not change the outcome. AS: Aortic stenosis; AVA: Aortic valve area; AVR: Aortic valve replacement; CHF: Congestive heart failure; CABG: Coronary artery bypass grafting; EF: Ejection fraction; LV: Left ventricular; MG: Mean valvular gradient.
(Figure omitted. See article PDF.)
Figure 3. Kaplan-Meier survival analysis of patients with severe aortic stenosis, low ejection fraction (<35%) and low mean transvalvular gradient (<30 mmHg). Patients with valve replacement had a significantly better survival than those in medical treatment (78 and 15%, respectively, at 4-year follow-up) (by permission from [34]).
(Figure omitted. See article PDF.)
Figure 4. Low gradient aortic stenosis Kaplan-Meier survival analysis. Comparison of patients with (group I) and without (group II) left-ventricular contractile reserve, defined as an increase in stroke volume of 20% or more from baseline during dobutamine infusion. The difference between surgical and medical...