Biomedical subjects

B Hartig

Publications and source records attributed to B Hartig.

4 recordsLinked to original sources

PubMed1998

The development of hemodynamics in the extracranial carotid and vertebral arteries.

To investigate the development of hemodynamics in the extracranial carotid and vertebral artery system, a prospective color duplex sonography study was performed in 94 healthy children and adolescents between 3 and 18 y old. Angle-corrected flow velocities and luminal diameters were measured; waveform parameters and flow volumes were calculated. Side-to-side differences of volumetric data were analyzed. In 53 children, an intrasession test-retest flowmetry of the internal carotid and vertebral arteries was performed. From 3 to 18 y old, flow volumes decreased significantly in the vertebral arteries (p < or = 0.01) and increased in the external carotid artery (p < or = 0.0001); the luminal diameter increased in all the carotid arteries (p < or = 0.0001) and remained constant in the vertebral arteries; mean flow velocities declined in the common and internal carotid arteries and in the vertebral arteries (p < or = 0.0001), but increased in the external carotid arteries (p < or = 0.01). Flow volume rate was lower in the right than the left vertebral artery (p < or = 0.0001), and there was no side difference in any of the carotid arteries. The test-retest correlation of volumetric data was high (0.81 < or = r < or = 0.97; p < or = 0.0001). By comparing the reference data presented here with analogous adult data, we were able to delineate the physiologic development of extracranial and cerebral hemodynamics from childhood to adulthood. These data make possible the clinical application of quantitative flowmetry in extracranial cerebral arteries of children and adolescents.

Adolescent↗

PubMed1996

Transcranial color duplex sonography of basal cerebral arteries: reference data of flow velocities from childhood to adulthood.

A prospective study on transcranial color duplex sonography (TCCD) was performed with 94 healthy children and adolescents between 3 and 18 years of age (age and sex evenly distributed) in order to provide normal data on angle-corrected ("true") flow velocities and wave-form parameters of the main supra- and infratentorial basal cerebral arteries. Using a 2.0 MHz transducer of a computed sonography system, we examined the anterior, middle, and posterior cerebral arteries of either side transcranially, and the vertebrobasilar system suboccipitally. In all arteries, flow velocities decreased continuously from early childhood to adulthood, while wave-form parameters remained constant. There was no difference in flow velocities, and wave-form parameters between girls and boys. On the average, the angle-corrected flow velocities measured by TCCD were about 10%-20% higher than the reference data provided in "blind" transcranial Doppler studies by other groups for the anterior and posterior cerebral arteries as well as the basilar artery, while there were only small differences in the values for the middle cerebral artery. Side-to-side differences in flow velocities were lower in the middle and posterior cerebral arteries than in the anterior cerebral and the vertebral arteries. The reference data presented here provide a basis for the clinical application of the TCCD method in children and adolescents.

Adolescent↗

PubMed1996

Age dependence of total cerebral blood flow volume from childhood to adulthood.

In a prospective study of the natural development of total cerebral blood flow volume (CBFV), the common, external and internal carotid and vertebral arteries were examined in 94 healthy children and adolescents between 3 and 18 years of age (sex and age evenly distributed) using a 7.0-MHz transducer of a computed sonography system. Intravascular flow volumes were calculated with the product of angle-corrected time-averaged flow velocity and the cross-sectional area of the vessel. CBFV was determined as the sum of flow volumes in the internal carotid and vertebral arteries of both sides. CBFV increased significantly between 3 and 6.5 years of age (from 687 +/- 85 to 896 +/- 110 ml/min; age correlation, p < or = 0.01) and declined thereafter (p < or = 0.001) to a constant level of approximately 700 ml/min at 15 years of age. There was no difference in CBFV between sexes. The proportion of bilateral vertebral artery flow volume in total CBFV decreased significantly between the ages of 3 and 18 years (p < or = 0.001). As the flow volumes of the external carotid arteries increased markedly from childhood to adulthood, flow volumes of the common carotid arteries were not representative of CBFV. Intrasession test-retest correlation of CBFV was high (r = 0.89, p < or = 0.0001). Reference data for the childhood years presented here and previously described results from healthy adults allow us to outline the natural evolution of CBFV in humans. The reliability of the method has already been demonstrated. Thus, it may now be introduced into clinical application.

Adolescent↗

PubMed1984

Stimulus context and infant orientation discrimination.

In three experiments, the effect of additional "contextual" elements on the discrimination of the orientation of linear and curvilinear segments was investigated with 4-month-old infants. In Experiment 1, paired visual matrices (one which contained some irregularity in orientation of internal elements, vs one which contained no irregularities) were presented. Infants detected irregular matrices significantly better than chance, but such detection was not aided by contextual elements. Discrimination of orientation in Experiment 2 was assessed with a paired-comparison familiarization-novelty paradigm. It was found that the addition of elements here significantly aided discrimination of linear segment orientation, but not curvilinear segment orientation. Experiment 3 investigated why this effect was not found for curvilinear segments; after equating the curvilinear stimuli to linear ones used in Experiment 2 with respect to the closedness of figure, discrimination of curvilinear orientation was observed.

Female↗