No abstract

The myocardial performance index (Tei index) determined by the pulsed Doppler method is a simple and noninvasive measurement for assessing global right ventricular (RV) function. This index can also be obtained by tissue Doppler imaging (TDI). The effects of significant pulmonary regurgitation (PR) on the determination of the Tei index by these two methods have not been investigated. We examined 15 patients (6.3 +/- 2.2 years) with significant PR after repair of tetralogy of Fallot (TOF) and 24 age-matched healthy children. Myocardial wall motion velocities at the tricuspid annulus were assessed during systole (Sa), early diastole (Ea), and late diastole (Aa) from a four-chamber view. Pulsed Doppler-Tei index and TDI-Tei index were measured as reported previously. The Tei index obtained by the pulsed Doppler method in TOF patients did not differ from that in normal children (0.30 +/- 0. 12 vs 0.32 +/- 0.07, p = not significant). TDI showed that TOF patients had significantly decreased Ea, Aa, and Sa velocities compared to those of normal children. Both isovolumic contraction time and isovolumic relaxation time in TOF patients were significantly longer than those in normal children (88 +/- 18 vs 62 +/- 23 msec and 46 +/- 11 vs 21 +/- 12 msec, respectively; p < 0.0001), although the duration of Sa did not differ between the two groups. Consequently, the Tei index as measured by TDI was significantly greater in TOF patients than in normal children (0.48 +/- 0.07 vs 0.30 +/- 0.07, p < 0.0001). The Tei index measured by the pulsed Doppler method is limited in its ability to assess RV function in patients with significant PR. However, the Tei index determined by TDI is a sensitive indicator of RV function in these patients, and it appears to be a promising new means of assessing global RV function in patients with significant PR.

Tissue Doppler imaging is a new ultrasound technology that derives measurements of contraction and relaxation velocities directly from the myocardium. However, data on myocardial velocities by using tissue Doppler imaging have not been established in normal children. In 48 normal children, myocardial velocities were measured using tissue Doppler imaging at three different sites (base, middle, and apex) in the left and right ventricles and the interventricular septum. In the left ventricular wall, the peak myocardial velocities during early diastole (peak E), during atrial contraction (peak A), and during systole (peak S) waves decreased gradually between the base and apical sites, whereas the ratio of E to A waves (peak E/A wave ratio) did not change among the 3 segments. Similar findings were obtained from the myocardial velocities in the right ventricle and the interventricular septum. A systolic and diastolic velocity gradient was also observed between the different ventricular walls. Significant correlations of the tissue Doppler parameters with age or heart rate were observed. In the left ventricle, the peak E wave demonstrated a stronger relation with age (r=0.77) than with heart rate (r=-0.65). The peak A wave did not change with age but correlated with heart rate. The peak E/A wave ratio showed a weaker relation with age (r=0.54) than with heart rate (r=0.62). The peak S wave was related to age (r=0.65) and to a lesser extent to heart rate (r= -0.51). Similar relationships of tissue Doppler parameters with age or heart rate were observed for the right ventricle and interventricular septum. The heterogeneous pattern and age- and heart-rate-related changes in normal myocardium demonstrated in this study must be taken into account when attempting to identify altered regional myocardial function with tissue Doppler echocardiography.

Compared with transmitral velocities of flow, myocardial wall velocities obtained by tissue Doppler imaging are less influenced by left atrial pressure. The data supporting this assumption, however, are limited in patients with congenital cardiac disease. The aim of this study was to compare the effects of left ventricular preload on transmitral inflow and velocities assessed by tissue Doppler imaging. Tissue Doppler imaging, and conventional Doppler echocardiography with simultaneous invasive hemodynamic studies, were performed in 33 patients with a simple ventricular septal defect or patency of the arterial duct. Transmitral velocities (E, A) and mitral annular velocities (Ea, Aa) were measured, permitting calculation of the ratio of E to Ea. The ratio of pulmonary to systemic flows, and mean left atrial pressure, were also measured. In 10 of 33 patients, echocardiographic and hemodynamic studies were performed 4 to 5 months after surgery. The E and A values in the patients were greater than those in the controls (p < 0.01). In contrast, neither Ea nor Aa differed between the two group. The ratio of E to Ea in the patients increased significantly compared with that in the controls (8.9+/-2.1 vs 7.3+/-1.3, p < 0.01). The E value was directly related to mean left atrial pressure and the ratio of pulmonary to systemic flows. The velocities measured by Tissue Doppler imaging, however, had no significant relationship to either of these measurements. The ratio of E to Ea correlated well with mean left atrial pressure (r = 0.75, p < 0.01). In 10 post-operative patients, the values for E and A decreased from 119+/-14 to 89+/-10 cm/sec (p < 0.01) and from 91+/-22 to 61+/-9 cm/sec (p < 0.01), respectively. No significant changes were noted in the values of Ea and Aa. The ratio of E to Ea, and mean left atrial pressure, decreased from 10.3+/-1.9 to 8.2+/-1.5 (p < 0.01) and from 11.0+/-1.8 to 7.4+/-1.0 mmHg (p < 0.01), respectively. The percentage change in left atrial pressure correlated with the percent change in the ratio of E to Ea (r = 0.64, p < 0.05). The present study showed that the velocities obtained with tissue Doppler imaging are less dependent on mean left atrial pressure in children with elevated left ventricular preload caused by a left-to-right shunt.

Dobutamine stress echocardiography has become accepted in the evaluation of cardiac functional reserve. Although the Doppler-derived index of combined systolic/diastolic myocardial performance (Tei index) has been reported to be easily obtainable and useful for predicting left ventricular performance, the effect of dobutamine on the Tei index has not been determined in children. To assess the effect of dobutamine on the Tei index, 8 patients who had undergone surgery for ventricular septal defect and 7 patients who had a history of Kawasaki disease were examined. Echocardiographic recordings were obtained before and after dobutamine infusion (5 microg/kg per minute). Variables measured were transmitral flow velocities (E, A, E/A), rate-corrected mean velocity of circumferential fiber shortening (rate-corrected Vcf), and IMP. We measured isovolumic contraction time (ICT), isovolumic relaxation time (IRT), and ejection time (ET) and then calculated the Tei index using the following formula: Tei index = (ICT + IRT)/ET. Dobutamine infusion increased rate-corrected Vcf (29%, p < 0.01), peak E (7%, p < 0.05), and peak A (13%, p < 0.05). E/A ratio did not change during dobutamine infusion. ET, ICT, and IRT were found to decrease during dobutamine infusion. The magnitude of the change in the ICT (-21%, p < 0.01) was greater than those in IRT (-12%, p < 0.01) and ET (-8%, p < 0.05). The decrease in Tei index (-16%, p < 0.01) resulted in a decrease in ICT/ET (-21%, p < 0.01) and a slight decrease in IRT/ET (-12%, p < 0.05). The Tei index has potential as a sensitive indicator of the effects of inotropic stimilation on global left ventricular function.