title: Estimation of cardiac output and pulmonary vascular resistance by contrast echocardiography transit time measurement: a prospective pilot study.
abstract: BACKGROUND
  Studies with other imaging modalities have demonstrated a relationship between contrast transit and cardiac output (CO) and pulmonary vascular resistance (PVR). We tested the hypothesis that the transit time during contrast echocardiography could accurately estimate both CO and PVR compared to right heart catheterization (RHC).
  
  
  METHODS
  27 patients scheduled for RHC had 2D-echocardiogram immediately prior to RHC. 3 ml of DEFINITY contrast followed by a 10 ml saline flush was injected, and a multi-cycle echo clip was acquired from the beginning of injection to opacification of the left ventricle. 2D-echo based calculations of CO and PVR along with the DEFINITY-based transit time calculations were subsequently correlated with the RHC-determined CO and PVR.
  
  
  RESULTS
  The transit time from full opacification of the right ventricle to full opacification of the left ventricle inversely correlated with CO (r=-0.61, p<0.001). The transit time from peak opacification of the right ventricle to first appearance in the left ventricle moderately correlated with PVR (r=0.46, p<0.01). Previously described echocardiographic methods for the determination of CO (Huntsman method) and PVR (Abbas and Haddad methods) did not correlate with RHC-determined values (p = 0.20 for CO, p = 0.18 and p = 0.22 for PVR, respectively). The contrast transit time method demonstrated reliable intra- (p<0.0001) and inter-observer correlation (p<0.001).
  
  
  CONCLUSIONS
  We describe a novel method for the quantification of CO and estimation of PVR using contrast echocardiography transit time. This technique adds to the methodologies used for noninvasive hemodynamic assessment, but requires further validation to determine overall applicability.
authors.affiliation: The GW Heart & Vascular Institute, The George Washington University, Washington, DC, USA. bchoi@gwu.edu.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Choi
authors.forename: Reza
authors.initials: R
authors.lastname: Sanai
authors.forename: Benjamin
authors.initials: B
authors.lastname: Yang
authors.forename: Heather A
authors.initials: HA
authors.lastname: Young
authors.forename: Ramesh
authors.initials: R
authors.lastname: Mazhari
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Reiner
authors.forename: Jannet F
authors.initials: JF
authors.lastname: Lewis
mesh_terms: D000465:Algorithms; D006328:Cardiac Catheterization; D002302:Cardiac Output; D003198:Computer Simulation; D003287:Contrast Media; D004452:Echocardiography / Q000379:methods*; D005260:Female; D005466:Fluorocarbons; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D063177:Pulse Wave Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059289:Vascular Stiffness
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren