title: Doppler color flow "proximal isovelocity surface area" method for estimating volume flow rate: effects of orifice shape and machine factors.
abstract: Previously described Doppler color flow mapping methods for estimating the severity of valvular regurgitation have focused on the distal jet. In this study, a newer Doppler color flow technique, focusing on the flow proximal to an orifice, was used. This method identifies a proximal isovelocity surface area (PISA) by displaying an aliasing interface. Volume flow rate (cm3/s) can be calculated as PISA (cm2) x aliasing velocity (cm/s). For planar circular orifices, a hemi-elliptic model accurately approximated the shape of PISA. Clinically, however, orifice shapes may be noncircular. In vitro flow experiments (n = 226) using orifices of various shapes (ellipse, square, triangle, star, rectangle) were performed. Volume flow rate calculated using a hemi-elliptic model for PISA was accurate, with average percent differences from actual flow rate = +4.3% for a square, -4.2% for a triangle, -4.7% for a star, -4.5% for an ellipse and -2.8% for a rectangle. However, average percent differences for calculated volume flow rates using a hemispheric model for PISA shape ranged from -11.6% (square) to -34.8% (rectangle). In addition, to evaluate whether PISA is influenced by machine factors, in vitro studies (n = 83) were performed.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of California, Irvine.
authors.forename: T
authors.initials: T
authors.lastname: Utsunomiya
authors.forename: T
authors.initials: T
authors.lastname: Ogawa
authors.forename: R
authors.initials: R
authors.lastname: Doshi
authors.forename: D
authors.initials: D
authors.lastname: Patel
authors.forename: M
authors.initials: M
authors.lastname: Quan
authors.forename: W L
authors.initials: WL
authors.lastname: Henry
authors.forename: J M
authors.initials: JM
authors.lastname: Gardin
mesh_terms: D001783:Blood Flow Velocity; D004452:Echocardiography; D006439:Hemodynamics / Q000502:physiology; D008432:Mathematical Computing; D008955:Models, Cardiovascular; D011673:Pulsatile Flow / Q000502:physiology