title: A novel Doppler echocardiographic method of measuring the biophysical properties of the aorta in pediatric patients.
abstract: BACKGROUND
  This study was performed to: (1) assess the feasibility of measuring pulse wave velocity (PWV) from aortic (AO) Doppler flow and deriving AO input and characteristic impedances and the arterial pressure strain elastic modulus; and (2) compare these indices in pediatric patients with arterial disease to control (C) patients.
  
  
  METHODS
  There were 14 healthy children in the C group, 9 with inflammatory connective tissue diseases (ICTD), and 6 with Marfan syndrome (M). Using standard echocardiographic equipment, the AO annulus, AO root diameter in systole (AO(S)) and diastole (AO(D)), and AO length (L) were measured. The time taken for the Doppler signal to travel from the ascending to descending aorta was measured. AO peak flow was calculated from AO annulus cross-sectional area x peak aortic velocity (AoV); PWV = L/time taken for the Doppler signal to travel from the ascending to descending aorta; input impedance = (systolic - diastolic blood pressure)/(AO cross-sectional area x AoV); characteristic impedance = (PWV x rho)/Ao cross-sectional area (where rho = 1.06); and pressure strain elastic modulus = (systolic - diastolic blood pressure)/[(AO(S) - AO(D))/AO(D)]; beta index = ln (systolic/diastolic blood pressure)/[(AO(S) - AO(D))/AO(D)].
  
  
  RESULTS
  Results for PWV were ICTD = M > C (533, 496, 362 cm/s; P <.02); for input impedance were ICTD > M = C (245, 120, 116; P <.03); for characteristic impedance were ICTD < M = C (249, 107, 142; P <.05); for pressure strain elastic modulus were M > ICTD = C (262, 447, 187; P <.003); and for beta index were M > ICTD > C (2.91, 2.51, 2.13; P <.0006).
  
  
  CONCLUSIONS
  This novel, relatively simple method of assessing the biophysical properties of the aorta shows abnormal function in patients with M and ICTD. This technique may be helpful in the long-term follow up of patients with arterial disease.
authors.affiliation: Department of Pediatrics, British Columbia's Children's Hospital, Vancouver, Canada.
authors.forename: George G S
authors.initials: GG
authors.lastname: Sandor
authors.forename: Takashi
authors.initials: T
authors.lastname: Hishitani
authors.forename: Ross E
authors.initials: RE
authors.lastname: Petty
authors.forename: Mary T
authors.initials: MT
authors.lastname: Potts
authors.forename: Astrid
authors.initials: A
authors.lastname: Desouza
authors.forename: Eustace
authors.initials: E
authors.lastname: Desouza
authors.forename: James E
authors.initials: JE
authors.lastname: Potts
mesh_terms: D000293:Adolescent; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016022:Case-Control Studies; D002648:Child; D003240:Connective Tissue Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology; D015150:Echocardiography, Doppler / Q000379:methods*; D018618:Echocardiography, Doppler, Color; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008382:Marfan Syndrome / Q000000981:diagnostic imaging / Q000503:physiopathology; D011673:Pulsatile Flow / Q000502:physiology