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Titolo:
A method for determining the reference effective flow areas for mechanicalheart valve prostheses - In vitro validation studies
Autore:
Shandas, R; Kwon, J; Valdes-Cruz, L;
Indirizzi:
Childrens Hosp, Cardiovasc Flow Res Lab, Denver, CO 80218 USA Childrens Hosp Denver CO USA 80218 asc Flow Res Lab, Denver, CO 80218 USA
Titolo Testata:
CIRCULATION
fascicolo: 16, volume: 101, anno: 2000,
pagine: 1953 - 1959
SICI:
0009-7322(20000425)101:16<1953:AMFDTR>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHRONIC ANIMAL-MODEL; ORIFICE AREA; PULSATILE FLOW; VENA CONTRACTA; MITRAL-VALVE; IN-VITRO; SIMULTANEOUS DOPPLER; CONTINUITY EQUATION; AORTIC-STENOSIS; GORLIN FORMULA;
Keywords:
blood flow; valves; echocardiography;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
22
Recensione:
Indirizzi per estratti:
Indirizzo: Shandas, R Childrens Hosp, Cardiovasc Flow Res Lab, 1056 E 19th Ave,B-100,Denver, CO80218 USA Childrens Hosp 1056 E 19th Ave,B-100 Denver CO USA 80218 18 USA
Citazione:
R. Shandas et al., "A method for determining the reference effective flow areas for mechanicalheart valve prostheses - In vitro validation studies", CIRCULATION, 101(16), 2000, pp. 1953-1959

Abstract

Background-The anatomic opening area (AOA) is usually reported as the primary index of mechanical heart valve function. Because flow contracts immediately distal to an orifice as a result of the vena contracta effect, AOA may not be a good measure of true effective flow area. Methods and Results-Laser flow imaging was used to visualize the contraction in the jet flow stream as it passed through bileaflet mechanical valves under steady and pulsatile conditions. Such visualization allowed clear measurement of the individual vena contracta areas (VCAs) of the 3 valve orifices. VCAs for side orifices were larger (94+/-2% of AOA) than those throughthe central orifice (34+/-8%). Formation of large radial vortices around the leaflet tips constricted the central orifice flow stream and appeared tobe the main reason for smaller central VCA. Total VCA remained constant until approximate to 0.5 orifice diameters (approximate to 1.0 cm) downstream, beyond which cross-sectional area increased as a result of entrainment ofreceiving chamber flow. Total VCA was larger for steady flow (89.6+/-2.7% of AOA) than for pulsatile flow (76.3+/-5.0% of AOA). Conclusions-This study further clarifies flow dynamics through bileaflet mechanical valves and provides previously unavailable reference information on VCAs for these valves. Such information should aid clinicians in explaining Doppler-derived and catheter-measured pressure discrepancies, validating clinical techniques for quantifying effective flow areas, and optimizing valve size for implantation. The method should also be useful for comparative studies of different valve designs.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/11/20 alle ore 22:42:30