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- BNP, type B natriuretic peptide
- CAD, coronary artery disease
- EBCT, electron beam computed tomography LV, left ventricle
- LVEF, left ventricular ejection fraction
- SPECT, single photon emission computed tomography
The quantitation of left ventricle (LV) volumes and ejection fraction is an important aspect of cardiac evaluation in all cardiac disorders. Prognosis in many types of heart disease is closely related to global left ventricular ejection fraction (LVEF), falling off rapidly as the ejection fraction falls below 40% (fig 1). However, although ejection fraction has the advantage of being a simple numerical parameter that reflects LV function, it is strongly influenced by loading conditions and does not correlate well with symptom status. Perhaps more importantly, although two dimensional (2D) ejection fraction is meaningful when applied across populations or to stratify risk in individuals, its value as a sequential test within individuals is constrained by limited test–retest reliability.
GLOBAL FUNCTION ASSESSMENT BY 2D ECHOCARDIOGRAPHY
Subjective assessment
Whatever the limitations of subjective assessment, the reality is that echocardiographic assessment of global left ventricular systolic function is usually performed subjectively. Moreover, the eye of an experienced observer is comparable to trackball measurements.1 The situations where this approach can be misleading are when the rhythm is irregular (when examining a long tape run rather than individual cine loops is essential), the LV size is very large or very small, and at the extremes of heart rate.
Measurement of ventricular volumes and ejection fraction
Two dimensional echocardiography approaches for calculation of LV volumes have largely superseded M mode echocardiography techniques that used geometric assumptions based on the minor dimension of the ventricle. A number of 2D approaches have been described (table 1),2–4 some using more sophisticated geometric assumptions. With each of these methods, once volumes have …