title: Flow acceleration time and ratio of acceleration time to ejection time for prosthetic aortic valve function.
abstract: OBJECTIVE
  We sought to evaluate whether ejection dynamics, particularly acceleration time (AT) and the ratio of AT to ejection time (ET), can differentiate prosthetic aortic valve (PAV) stenosis from controls and prosthesis-patient mismatch (PPM).
  
  
  BACKGROUND
  Diagnosing PAV stenosis, especially in mechanical valves, may be challenging and has significant clinical implications.
  
  
  METHODS
  Doppler echocardiography was quantitated in 88 patients with PAV (44 mechanical and 44 bioprosthetic; age 63 ± 16 years; valve size range 18 to 25 mm) of whom 22 patients had documented PAV stenosis, 22 had PPM, and 44 served as controls. Quantitative Doppler parameters included ejection dynamics (AT, ET, and AT/ET) and conventional PAV parameters.
  
  
  RESULTS
  Patients with PAV stenosis had significantly lower effective orifice area (EOA) values and higher gradients compared with controls and PPM. Flow ejection parameters (AT and AT/ET) were significantly longer in the stenotic valves compared with PPM and controls (respective values for AT: 120 ± 24 ms, 89 ± 16 ms, and 71 ± 15 ms; for AT/ET: 0.4, 0.32, and 0.3, p ≤ 0.001). Patients with PPM had gradients and ejection dynamics that were intermediate between normal and stenotic valves. Receiver-operator characteristic (ROC) curve analysis showed that AT and AT/ET discriminated PAV stenosis from PPM and controls (area under ROC curve = 0.92 and 0.88, respectively). Combining AT with the conventional Doppler velocity index gave the highest area under the curve of 0.98 but was not statistically different from that of AT alone (p = 0.12). A cutoff of AT = 100 ms had a sensitivity and specificity of 86% for identifying PAV stenosis; for an AT/ET = 0.37, the sensitivity and specificity were 96% and 82%, respectively. Analysis by valve type (mechanical and biological) revealed similar results; however, biological valves had slightly higher areas under the curve for all systolic time intervals.
  
  
  CONCLUSIONS
  Ejection dynamics through PAV, particularly AT and AT/ET, are reliable angle-independent parameters that can help evaluate valve function and identify PAV stenosis.
authors.affiliation: Cardiovascular Imaging Institute, Echocardiography Laboratory, The Methodist DeBakey Heart & Vascular Center, Houston, Texas 77030, USA.
authors.forename: Sagit
authors.initials: S
authors.lastname: Ben Zekry
authors.forename: Robert M
authors.initials: RM
authors.lastname: Saad
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ozkan
authors.forename: Maie S
authors.initials: MS
authors.lastname: Al Shahid
authors.forename: Mauro
authors.initials: M
authors.lastname: Pepi
authors.forename: Manuela
authors.initials: M
authors.lastname: Muratori
authors.forename: Jiaqiong
authors.initials: J
authors.lastname: Xu
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Little
authors.forename: William A
authors.initials: WA
authors.lastname: Zoghbi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D001705:Bioprosthesis; D015150:Echocardiography, Doppler; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D006801:Humans; D007558:Italy; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012529:Saudi Arabia; D013318:Stroke Volume; D013599:Systole; D013781:Texas; D013997:Time Factors; D014421:Turkey; D016277:Ventricular Function, Left