In vitro analysis of colour Doppler flow with the use of proximal isovelocity surface area: improved flow estimates using a nonhemispherical model.
Can J Cardiol
; 15(1): 89-94, 1999 Jan.
Article
em En
| MEDLINE
| ID: mdl-10024864
ABSTRACT
OBJECTIVE:
To examine the geometry of the proximal isovelocity surface area (PISA) envelope and its associated isotach, and to evaluate the accuracy of two models of calculating volumetric flow by using the PISA technique.DESIGN:
A new model for determining isotach geometry from the PISA envelope was developed and tested in an in vitro simulation.SETTING:
Echocardiography Laboratory, Hotel Dieu Hospital, Kingston, Ontario. MATERIALS ANDMETHODS:
PISA envelopes were visualized using an in vitro flow simulator with a series of sharp-edged orifices (2.5 to 16 mm diameter) at a range of flow rates (10 to 110 mL/s).INTERVENTIONS:
Flow calculations based on the traditional hemispherical geometric assumption for the isotach and the new model were made and compared with measured flow rates. MAINRESULTS:
The hemispherical model systematically and significantly underestimated flow. The nonhemispherical model, which requires measurement of both the height (a) and lateral width (2d) of the PISA envelope, provided improved estimates of flow.CONCLUSIONS:
The nonhemispherical model provides a better estimate of flow through an orifice. Flow rate Q can be calculated directly from the size of the PISA envelope and the aliasing velocity (VA) by using the relationship Q = (3.14d2 + 5.97da + 1.37a2)VA or can be read from a nomogram.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Reologia
/
Velocidade do Fluxo Sanguíneo
/
Ecocardiografia Doppler em Cores
Limite:
Humans
Idioma:
En
Ano de publicação:
1999
Tipo de documento:
Article