## Abstract Heparinless venoarterial bypass (HLβVAB) was carried out in 16 sheep for 6 days, by means of a closed circuit tubing coated with nonthrombogenic polyurethaneβpolyvinylβgraphite (PPG) and a roller pump. Nine experiments were completed uneventfully. Seven sheep died during bypass. The cau
Ultrasonic Characterization of Blood During Coagulation
β Scribed by K. Kirk Shung; Dingyu Fei Msee; Ying-Wei Yuan Bsbe; William C. Reeves
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 551 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0091-2751
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β¦ Synopsis
Abstract
Recently ultrasound has been found to be extremely useful in detecting intracardiac thrombi as well as intracranial hemorrhages in neonates. The principal criterion used for clinical diagnosis of thrombus has been an increase in the echogenicity of clotted blood. However, echogenicity is a rather nonspecific and qualitative description of tissue ultrasonic properties. A rise in echogenicity could be the result of an increase in ultrasonic backscatter, or a decrease in attenuation, or a combination of both. In order to ascertain the mechanism responsible for the clinically observed increase in echogenicity and thus put the technique on a firm foundation, we have measured serially the ultrasonic velocity, attenuation and backscatter in human blood up to 24 hours following the onset of coagulation. Preliminary results show that all three ultrasonic properties increase during this time period. At 24 hours following clotting, the mean rises in velocity, attenuation and backscatter are 3.36 Β± 0.35 Β± 10^3^ cm/sec, 2.3 Β± 0.22 db/cm and 18.5 Β± 1.2dB per unit volume of blood (at 7.5 MHz and a temperature of 23Β°C), respectively. These results indicate that the increase in echogenicity of a thrombus is due to a substantial increase in ultrasonic backscatter, which is moderated to a certain extent by the accompanied increase in attenuation.
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