All issues > Volume 30(9); 1987

Original Article

J Korean Pediatr Soc. 1987;30(9):972-981. Published online September 30, 1987.

Measurements of Blood Flow in the Ascending and Descending Aorta by Two-Dimensional doppler Echocardiography in School children.

Soon Ung Kang¹

¹Department of Pediatrics, College of Medicine, Seoul National University

Abstract

Cardiac output measurements are among the most important physiologic indices of cardiovascular function. Flow computation is one of the major capabilities of Doppler echocardiography. The basic principle is that the average velocity of blood flow multiplied by the area through which the blood passes yields flow volume. The normal range of diameters and velocities in the ascending and descending aorta were established in 76 healthy children aged 7 to 12 years. Computations of the ascending and descending aortic flows were also presented. The results were as follows: 1) Ascending aortic diameters (AAD) and descending aortic diameters (DAD) measured from center to center of the aortic wall image(I) and between internal margins(II) at the age of 7 years and 12 years were: (I) 17.3±0.7 mm, 20.8±l.lmm (AAD) and 14.1 ±0.6 mm, 16.8±1.0 mm (DAD), (II) 15.2±0. 8 mm, 18.2±1.0 mm (AAD) and 12.4±0.9 mm, 14.7±0.8 mm (DAD) respectively and both of aortic diameters enlarged with increasing age (p<0.01). The ratio (DAD/A AD) was 0.80 ±0.02 ⑴ and 0.80 ±0.03 (II), and relatively constant throughout all ages. 2) Maximum velocities in the ascending aorta (VmaxAA) and the descending aorta (VmaxDA) were 106 ±13 cm/sec and 129 ±13 cm/sec respectively and there was no significant difference with increasing age (p>0.05). The ratio (VmaxDA/VmaxAA) was 1.22±0.05 and relatively constant throughout all ages. 3) Ascending aortic flows (AAF) and descending aortic flows (DAF) using the diameters from center to center of the aortic wall image (I) and between internal margins (II) at the age of 7 years and 12 years were: (I) 2.83±0.27 L/min, 3.79 ±0.38 L/min (AAF) and 2.22 ±0.18 L/min, 3.01 ±0.40 L/ min (DAF), (II) 2.19±0.19 L/min, 2.88±0.30 L/min(AAF) and 1.72±0.17 L/min, 2.31 ±0.24 L/min (DAF) respectively. The former was more close to the known normal cardiac output for age than the latter. Both of the aortic flows increased with increasing age (p<0.01). The ratio (DAF/AAFX100) was 79.6±4.9% (I) and 79.3 ±3.5% (II), and relatively constant throughout all ages. 4) The increase in the ascending aortic flows correlated closely with the increase in the aortic diameters (r=0.66, p<0.01). Thus growth of aortic cross section keeps pace with the increase in cardiac output that occurs over this growing period. 5) Ascending aortic flows per m2 of body surface area decrease gradually with increasing age (p <0.01). 6) These findings suggest that cardiac output can be estimated through the descending aortic flow multiplied by 1.25

Keywords :Two-dimensional Doppler echocardiography; Ascending aorta; Descending aorta; Cardiac output