In addition, TTE is useful for measuring LV size and systolic function, identifying concurrent AR or MR, and estimating pulmonary systolic 2. Measurements of AS severity made when the patient is hypertensive may underestimate or, less often, overestimate stenosis severity. Systemic hypertension imposes a second pressure load on the LV, in addition to valve obstruction, which CLINICAL STATEMENTS AND GUIDELINES results in a lower forward stroke volume and lower transaortic pressure gradient than when the patient is normotensive. Thus, Doppler veloc- ity data and invasive pressure measurements ideally are recorded when the patient is normo- tensive. If results indicate only moderate stenosis but were recorded when the patient was hyper- tensive, repeat measurements when the blood pressure is better controlled ensure that a diag- nosis of severe AS is not missed. 3. Patients with severe AS and LVEF <50% present with an aortic valve area <1.0 cm2 but a low transvalvular velocity and pressure gradient (ie, velocity <4 m/s or mean gradient <40 mm Hg) at rest. In these patients, severe AS with LV systolic dysfunction attributable to afterload Table 13. 