Impact of preload alteration on left ventricular mechanical dyssynchrony using tissue velocity imaging echocardiography.
ABSTRACT We lack full understanding on the determinants of left ventricular (LV) systolic mechanical dyssynchrony. We here tried to evaluate the effect of preload alterations on LV dyssynchrony using echocardiographic tissue velocity imaging.
Thirty-eight patients with a history of heart failure who were in sinus rhythm (24 men, mean age of 61 ± 12 years [range, 26-82]) were consecutively recruited. Twenty-four patients were allocated into a mild diastolic dysfunction group (Gr 1), and 14 to an advanced diastolic dysfunction group, which included pseudonormalization or restrictive mitral inflow patterns (Gr 2). The leg-raising maneuver was performed for 5 minutes in Gr 1, whereas two tablets (1.2 mg) of sublingual nitroglycerin (SLNG) were given to Gr 2 to manipulate preload status. An index representing LV systolic mechanical dyssynchony (DYSsys) was defined as the maximal differences in time intervals from the QRS onset to the systolic peak velocities in 4 basal segments derived from the apical four- and two-chamber views.
DYSsys decreased significantly after SLNG administration (74.2 ± 50.2 vs. 46.9 ± 34.8 ms, P < 0.01), whereas it showed a significant elevation after leg-raising maneuver (76.3 ± 33.5 vs. 88.8 ± 37.5 ms, P < 0.05). Maximal difference in DYSsys between before and after SLNG administration in a patient of Gr 2 was estimated to be 120.2, whereas with the leg-raising maneuver, maximal difference in DYSsys in a patient of Gr 1 was found to be 66.8. Changes in heart rate induced by preload manipulation did not display any association with changes in DYSsys.
DYSsys is significantly affected by preload alterations, and thus it can be considered a "dynamic" parameter that could be modified depending on the loading status. Therefore, loading status of individual patients should be considered when DYSsys is assessed.
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ABSTRACT: Objectives. This study assessed the clinical utility of mitral annulus velocity in the evaluation of left ventricular diastolic function.Background. Mitral inflow velocity recorded by Doppler echocardiography has been widely used to evaluate left ventricular diastolic function but is affected by other factors. The mitral annulus velocity profile during diastole may provide additional information about left ventricular diastolic function.Methods. Mitral annulus velocity during diastole was measured by Doppler tissue imaging (DTI) 1) in 59 normal volunteers (group 1); 2) in 20 patients with a relaxation abnormality as assessed by Doppler mitral inflow variables (group 2) at baseline and after saline loading; 3) in 11 patients (group 3) with normal diastolic function before and after intravenous nitroglycerin infusion; and 4) in 38 consecutive patients (group 4) undergoing cardiac catheterization in whom mitral inflow velocity and tau as well as mitral annulus velocity were measured simultaneously.Results. In group 1, mean ± SD peak early and late diastolic mitral annulus velocity was 10.0 ± 1.3 and 9.5 ± 1.5 cm/s, respectively. In group 2, mitral inflow velocity profile changed toward the pseudonormalization pattern with saline loading (deceleration time 311 ± 84 ms before to 216 ± 40 ms after intervention, p < 0.001), whereas peak early diastolic mitral annulus velocity did not change significantly (5.3 ± 1.2 cm/s to 5.7 ± 1.4 cm/s, p = NS). In group 3, despite a significant change in mitral inflow velocity profile after nitroglycerin, peak early diastolic mitral annulus velocity did not change significantly (9.5 ± 2.2 cm/s to 9.2 ± 1.7 cm/s, p = NS). In group 4, peak early diastolic mitral annulus velocity (r = −0.56, p < 0.01) and the early/late ratio (r = −0.46, p < 0.01) correlated with tau. When the combination of normal mitral inflow variables with prolonged tau (≥50 ms) was classified as pseudonormalization, peak early diastolic mitral annulus velocity <8.5 cm/s and the early/late ratio <1 could identify the pseudonormalization with a sensitivity of 88% and specificity of 67%.Conclusions. Mitral annulus velocity determined by DTI is a relatively preload-independent variable in evaluating diastolic function.Journal of the American College of Cardiology 08/1997; · 14.09 Impact Factor