To investigate the effects of dobutamine on the Doppler transmitral flow pattern in children with normal left ventricular function, Doppler echocardiography was used to measure the transmitral flow in 14 healthy children before and during infusion of dobutamine (5 micrograms/kg per minute). Cardiac output was measured by the thermodilution method, and stroke volume was calculated as the cardiac output divided by the heart rate. Dobutamine increased the peak velocity and flow velocity-time integral of early diastolic filling without changing those of atrial contraction and normalized peak velocity of early diastolic filling, suggesting an increase in left ventricular relaxation. Dobutamine increased the stroke volume and rate-corrected mean velocity of fiber shortening with reduced end-systolic wall stress, indicating an increase in left ventricular contractility. The percentage of increase in the flow velocity-time integral of early diastolic filling during dobutamine infusion tended to correlate with the increase in stroke volume (r = 0.67, p < 0.05) and with the decrease in end-systolic wall stress (r = -0.61, p < 0.05). Our results suggest that low-dose dobutamine increases left ventricular relaxation with enhanced systolic function. The observed decreased endsystolic wall stress might have caused enhanced relaxation characteristics with dobutamine.

Cardiac Output↗

PubMedDate not supplied

Role of gestational age and body weight on Doppler transmitral flow velocity pattern in very low birth weight infants.

Doppler transmitral flow velocity was measured in premature infants. The early diastolic peak velocity, the peak velocity of early diastole/peak velocity of atrial contraction ratio, and total flow velocity-time integral increased significantly with advancing gestational age and body weight. The peak filling rate normalized to stroke volume (NPFR) did not correlate with gestational age or body weight. Moreover, mean NPFR was not significantly different between premature and term infants. Thus NPFR demonstrates that changes in the left ventricular filling patterns with advancing gestational age and increasing body size are related to the progressive increase in loading conditions, rather than to sequential changes in myocardial properties.

Birth Weight↗

PubMedDate not supplied

Effect of dobutamine on a Doppler echocardiographic index of combined systolic and diastolic performance.

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.

Adolescent↗