Measurement of cardiac time intervals by Doppler tissue M-mode imaging of the anterior mitral leaflet.

OBJECTIVE: We sought to evaluate a new method of measuring cardiac time intervals from Doppler tissue imaging (DTI) of the anterior leaflet of the mitral valve.
BACKGROUND: For a reliable analysis of the regional cardiac performance by DTI, a reference of time intervals of global cardiac events in the same cardiac cycle and based on the same imaging modality is required to reduce measurement error.
METHODS: We conducted a comparison of the measurements of isovolumic contraction and relaxation time and left ventricular (LV) ejection time by DTI M-mode analysis of the anterior mitral leaflet and the traditional approach based on spectral Doppler recordings. The measurements were done in 20 control subjects and 40 patients with cardiac diseases known to affect cardiac time intervals: heart failure, aortic stenosis, and essential hypertension with LV hypertrophy.
RESULTS: Mean difference in milliseconds (95% limits of agreement) of measurements were not different overall (-0.20 [-10.58; 10.18], -1.95 [-16.66; 12.76], 1.48 [-8.34; 11.34], and 0 [-0.06; 0.07] for isovolumic contraction time, LV ejection time, isovolumic relaxation time, and calculated index of myocardial performance, respectively). Intraobserver variability was low. Analysis of patients with different categories of cardiac diseases confirmed the expected values for time intervals and index of myocardial performance.
CONCLUSIONS: Measurement of isovolumic periods and LV ejection time was feasible and reliable by DTI M-mode analysis of the anterior mitral valve leaflet. The DTI method can, therefore, be used for obtaining information of global events in the cardiac cycle from the same heart beat as used for analysis of regional cardiac performance.

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