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Biomedical subjects

I A Simpson

Publications and source records attributed to I A Simpson.

148 records · Page 9Linked to original sources

Color flow Doppler mapping studies of "physiologic" pulmonary and tricuspid regurgitation: evidence for true regurgitation as opposed to a valve closing volume.

Color flow Doppler mapping using either an Aloka 880 or a Toshiba SSH65A system was performed in 39 normal subjects (aged 13 to 45 years) and 43 patients (aged 13 to 82 years) with pathologic tricuspid or pulmonary regurgitation to evaluate the incidence of "physiologic" regurgitation of right heart valves and to determine the differentiating characteristics in the spatial distribution and velocity encoding of "normal" and "pathologic" regurgitant jets. In the normal subjects, tricuspid and pulmonary regurgitation were documented in 32 (83%) and 36 (93%), respectively, and were unrelated to the system being used. Flow acceleration and aliasing were imaged on the right ventricular side of the tricuspid regurgitant orifice and on the pulmonary artery side of the pulmonary valve (in both normal subjects and patients), and indicated flow convergence for true regurgitation through an orifice as opposed to blood being driven retrogradely by the closing valve. Such proximal acceleration was documented in all patients with pathologic tricuspid regurgitation, in 31/32 of the normal subjects with tricuspid regurgitation, and was also observed in 12/15 (80%) of the patients and 4/12 (33%) of normal subjects with pulmonary regurgitation who were examined with the Toshiba system. The dimensions (mean +/- SD) of tricuspid regurgitant jets (length [JL] and area [JA]) were consistently larger in the patients than in the normal subjects [JL: 3.4 +/- 0.9 vs 1.2 +/- 0.5 cm, p less than 0.001; and JA: 5.7 +/- 2.0 vs 1.4 +/- 0.7 cm2, p less than 0.001) as were the pulmonary regurgitation jet dimensions (JL: 1.8 +/- 0.4 vs 0.9 +/- 0.08 cm, p less than 0.001; JA: 1.8 +/- 0.7 vs 0.3 +/- 0.08 cm2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Colour Doppler flow mapping: providing an insight into cardiac hydrodynamics.

Colour Doppler flow mapping can now provide spatial velocity information in relation to surrounding structural detail as imaged by conventional echocardiography and, as such, represents a major advance in non-invasive cardiac imaging. This article describes the basic principles of colour Doppler flow mapping, details how the Doppler information is processed and displayed to arrive at the real-time two-dimensional flow-enhanced image. Since colour Doppler flow mapping is really the first available technique which allows detailed real-time velocity information to be displayed in vivo and in relation to intracardiac structures, it can allow important insight into the haemodynamics of intracardiac flow. With the application of digital computer analysis techniques it may also be possible to extract valuable quantitative information from colour Doppler flow mapping.

Blood Flow Velocity↗

Transoesophageal echocardiography.

Transoesophageal echocardiography is a major diagnostic imaging technique with a wide range of clinical indications. Its use in cardiovascular diagnosis overcomes all the limitations of conventional transthoracic cardiac ultrasound imaging and it is now the investigation of choice in some areas.

Cardiovascular Diseases↗