Normal Values for the Assessment of Left Ventricular Function a
|Left ventricular ejection fraction (%)||≥52 (males)≥54 (females)|
|Stroke volume (mL), range||70-100|
|Rate of ventricular pressure rise (mm Hg/s)||>1200|
|Global longitudinal strain (2-D) (%), mean (range)||−20 (−15.9 to −22.1)|
|Global circumferential strain (2-D) (%), mean (range)||−23 (−20.9 to −27.8)|
|Global radial strain (2-D) (%), mean (range)||+47 (+35.1 to +59.0)|
a2-D = two-dimensional.
Pena que a técnica abaixo não vingou na rotina
Doppler Assessment of Stroke Volume
Cardiac stroke volume can be estimated by multiplying the velocity-time integral obtained from Doppler examination of the LV outflow tract by the LV outflow tract area . Doppler examination requires parallel alignment of the pulse-wave beam with the LV outflow tract. Nonparallel beam alignment can result in a reduced LV stroke volume by underestimating the velocity-time integral. Furthermore, this method requires accurate estimation of the LV outflow tract diameter; minor inaccuracies in diameter estimation result in marked errors in the area calculation because of the squaring of the radius.
Mas padece dos mesmos vícios que a estimativa de área valvar na estenose aórtica.
Assessment of LV function remains the most common reason for cardiac imaging because of its powerful ability to predict morbidity and mortality. Current routine methods of quantifying LV function (with LVEF) is not without limitations. Strain imaging that uses speckle tracking in 2-D and 3-D offers promise for quantifying LV function, particularly for patients with borderline LV function, because of the potential to identify subclinical disease. Strain imaging offers the treating physician a unique opportunity to alter management before the onset of overt LV dysfunction, which may, in turn, improve prognosis.