A simplified normalized ejection phase index measured by Doppler echocardiography for the assessment of left ventricular performance.

Although useful for the assessment of directional changes in contractility in individual patients, resting peak aortic blood velocity is of limited value for differentiating among patients with different levels of basal cardiac function. A dimensional analysis based on fluid dynamics shows that peak aortic blood velocity is not only generated by the contracting myocardium but also reflects the convective acceleration of blood from the left ventricle to the aorta. The reduction of cross-sectional area from the midleft ventricle to the aorta at the time of peak aortic blood velocity generates the convective acceleration. Accordingly, a higher convective acceleration due to left ventricular (LV) enlargement as observed in cardiomyopathy may explain why peak aortic blood velocity can be maintained as normal although myocardial contractility is depressed. This study tested the hypothesis that peak aortic blood velocity normalized by the ratio of midleft ventricle to aortic cross-sectional areas might provide a reliable index of LV performance. Nine normal control subjects and 25 patients undergoing catheterization were studied by M-mode, 2-dimensional and Doppler echocardiography. The normalized peak velocity measured noninvasively showed a high correlation with angiographic ejection fraction (r = 0.90, p less than 0.0001). Peak aortic blood velocity and the ratio of midleft ventricle to aortic cross-sectional areas alone correlated less well with ejection fraction (r = 0.76 and r = 0.75, p less than 0.0001, respectively). Furthermore, peak aortic blood velocity showed a significant overlap between patients with normal and those with abnormal LV function, whereas normalized peak aortic blood velocity was a better discriminator.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler echocardiographic measurement of low velocity motion of the left ventricular posterior wall.

A new noninvasive method using pulsed Doppler echocardiography was developed to assess left ventricular (LV) posterior wall motion dynamics. Seventeen normal subjects and 23 patients undergoing cardiac catheterization were prospectively studied. The sample volume was placed within the LV posterior wall endocardium just apical to the mitral valve sulcus using a posteriorly angulated low parasternal view. The wall filter was set at 100 Hz to record the low velocities of the LV posterior wall motion. The Doppler signal was morphologically similar to the rate of change of the LV posterior wall endocardium excursion obtained by a digitized M-mode echocardiogram, and showed 3 major waves: a systolic wave (S), an early diastolic wave (E) and a late diastolic wave (A). The peak velocities of LV posterior wall endocardium excursion were also determined by M-mode echocardiographic technique. We found a significant linear correlation between peak E-wave velocity and M-mode peak diastolic endocardial velocity (r = 0.90, p less than 0.001) and between peak S-wave velocity and M-mode peak systolic endocardial velocity (r = 0.81, p less than 0.001). M-mode peak systolic endocardial velocity showed an important overlap between control subjects and patients with normal and patients with abnormal LV posterior wall motion on the angiogram. In contrast, peak S-wave velocity was a better discriminator, and a peak S-wave velocity less than 7.5 cm/s was associated with abnormal LV posterior wall motion with an 83% sensitivity, 100% specificity and 95% accuracy. In patients with coronary artery disease but normal systolic LV posterior wall motion and normal global systolic LV function, peak S-wave velocity was not different when compared to control subjects. Peak E-wave velocity and E/A were significantly lower than in control subjects (p less than 0.01) and peak A-wave velocity was greater (p less than 0.01). In conclusion, these data suggest that pulsed Doppler echocardiography can be used for the direct analysis of LV posterior wall instantaneous low velocities and appears to be more informative than M-mode technique for systolic measurements. Thus, detection of abnormal LV posterior wall diastolic motion by pulsed Doppler echocardiography may, upon additional confirmation, be used as a new noninvasive method to gain insight into global LV diastolic performance.

A new Doppler method of assessing left ventricular ejection force in chronic congestive heart failure.

A noninvasive method using Doppler echocardiography was developed to determine the force exerted by the left ventricle in accelerating the blood into the aorta. The value of this new Doppler ejection index in the assessment of left ventricular (LV) performance was tested in 36 patients with chronic congestive heart disease undergoing cardiac catheterization and in 11 age-matched normal control subjects. The 36 patients were subgrouped into 3 groups based on angiographic ejection fraction (LV ejection fraction greater than 60, 41 to 60 and less than or equal to 40%). According to Newton's second law of motion (force = mass X acceleration), the LV ejection force was derived from the product of the mass of blood ejected during the acceleration time with the mean acceleration undergone during that time. In patients with LV ejection fraction less than or equal to 40%, LV ejection force, peak aortic velocity and mean acceleration were severely depressed when compared with the other groups (p less than 0.001). In patients with LV ejection fraction of 41 to 60%, LV ejection force was significantly reduced (22 +/- 3 kdynes) when compared with normal subjects (29 +/- 5 kdynes, p = 0.002) and with patients with LV ejection fraction greater than 60% (29 +/- 7 kdynes, p = 0.009); peak velocity and mean acceleration did not differ between these 3 groups. The LV ejection force showed a good linear correlation with LV ejection fraction (r = 0.86) and a better power fit (r = 0.91). Peak aortic blood velocity and mean acceleration showed less good linear correlations with LV ejection fraction (r = 0.73 and r = 0.66, respectively). The mass of blood ejected during the acceleration time also showed a weak linear correlation with LV ejection fraction (r = 0.64). An LV ejection force less than 20 kdynes was associated with a depressed LV performance (LV ejection fraction less than 50%) with 91% sensitivity and 90% specificity. Thus, these findings suggest that LV ejection force is a new Doppler ejection phase index that appears to be more accurate than peak aortic blood velocity and mean acceleration for the assessment of systolic LV function.