Assessment of left ventricular systolic function in research and in clinical practice.

Left ventricular (LV) systolic function is a major prognos-tic factor in cardiac disease 1–3 ; the serial reliable assessment of LV function is therefore essential. Since its development, echocardiography has played a major role in non-invasive evaluation. M mode echocardiography With the increasing sophistication of two dimensional echocardiography, it is notable that two groups with papers in this issue have used the very basic technique of M mode (one dimensional) echocardiography in the assessment of LV function. M mode measurements allow excellent resolution in measurement of LV diameters and wall thickness. Mahon and colleagues 4 have taken advantage of this to identify LV enlargement in relatives of patients with dilated cardiomyopathy and then elegantly demonstrated metabolic abnormalities in these patients. The population based heart failure study by Cowie and colleagues 5 illustrates the limitations of M mode. It should be noted that echocardiography was not a primary focus of this study. Qualitative two dimensional and M mode echocardiographic findings were not significantly associated with outcome. In this heterogeneous group, M mode was likely inadequate for assessment of LV function. Data were missing in over 50% of patients, possibly because of the technical limitations of M mode. M mode has shown little evolution until the relatively recent development of anatomic M mode, 6 which allows independent positioning of M mode cursors on cine loops. This technique may have a role for patients with unusual imaging planes and in stress echocardiography. Two dimensional quantitative assessment of LV function While M mode echocardiography still has applications, two dimensional imaging is critical for assessment of LV function in most patients. LV systolic function is frequently assessed visually. 7 The general validity of this has been shown, although wide ranges of interobserver variability have been reported. Visual estimation is clinically useful, but unreliable for patients with very poor images, of limited value in serial evaluation, and inadequate for patients in whom LV volumes critically aVect timing of intervention. M mode measurements can be converted to LV volumes, but compounds errors and is inaccurate in regional LV dysfunction and spherical ventricles. Multiple algorithms may be used to calculate LV volumes from two dimensional traces; all involve some geometric assumptions. The area–length method (symmetrical ventricles) and the apical biplane sum-mation of discs method (asymmetrical ventricles) are validated and normal values are available. 8 Opinions for and against the use of quantitative two dimensional echocardio-graphy largely revolve around …