Effects of dobutamine on coronary flow velocity response and their relations to age

Normal values for left anterior descending coronary artery flow velocity assessed by transthoracic doppler echocardiography in healthy children

Normal values for left anterior descending coronary artery (LAD) flow velocity were assessed from a large number of normal children. In 303 healthy children, LAD peak flow velocity was measured by Doppler echocardiography. LAD peak flow velocities were calculated considering the angle between the Doppler beam and the coronary flow direction. The flow signals of LAD were recorded in 95% (288/303). The mean angle between the Doppler beam and Doppler flow signals of LAD was 42 +/- 8 degrees. The ratio of AT to total diastolic spectral duration was 0.19 +/- 0.088 and constant with age. LAD peak flow velocity correlated significantly with age (r = -0.57, p < 0.0001) and heart rate (r = 0.63, p < 0.0001). Multiple linear regression analysis showed that LAD peak flow velocity was associated with age and heart rate (LAD peak flow velocity = 20-0.34 (age) + 0.16 (heart rate), r2 = 0.41, p < 0 .0001). Normal data obtained in the present study provide a basis of the understanding and investigation in children with congenital heart disease or acquired heart disease such as atherosclerosis, left ventricular hypertrophy, or Kawasaki's disease.

Left ventricular systolic and diastolic function during early neonatal period using transthoracic echocardiography

To examine the effects of ductal closure on left ventricular (LV) systolic and diastolic function during the early neonatal periods, 45 normal term neonates delivered after uncomplicated pregnancies (mean 39 weeks) were studied using two-dimensional and Doppler echocardiography. We measured ductus arteriosus size, arterial blood pressures, ascending aortic size, LV dimensions, and transmitral flow velocity patterns and calculated LV output and rate-corrected fiber shortening fraction (mVcfc) at 2, 12, 24, and 120 hours after birth. The inner diameter of the ductus arteriosus was 4.3 +/- 0.7mm at 2 hours, 2.1 +/- 0.6 mm at 12 hours, and had closed in 42 of 45 neonates at 24 hours. LV output and LV end-diastolic dimension showed the highest level at 2 hours of age. However, the mVcfc did not change from 2 to 120 hours of age. The peak velocity during early diastole (peak E) was significantly greater at 2 hours than at 12 hours. The peak velocity during atrial contraction (peak A) remained unchanged during this period. The normalized peak filling rate at isovolumic relaxation time did not change over 120 hours. The present study demonstrated changes in LV systolic function and LV diastolic filling during the early neonatal period. LV systolic and diastolic function was preserved under the hemodynamic changes associated with the early neonatal period.