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Effective systolic orifice area of the aortic valve: implications for Doppler echocardiographic cardiac output determinations
Author(s) -
Schmidt C.,
Theilmeier G.,
Van Aken H.,
Flottmann C.,
Wirtz S. P.,
Kehl HG.,
Hoffmeier A.,
Berendes E.
Publication year - 2005
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2005.00763.x
Subject(s) - medicine , body orifice , cardiology , aortic valve , stroke volume , equilateral triangle , cardiac output , hemodynamics , blood pressure , geometry , heart rate , anatomy , mathematics
Background: Substantial research using echocardiography has established that stroke volume (SV) or cardiac output (CO) can be measured non‐invasively at the level of the aortic valve (AV) with high accuracy. Stroke volume is the product of the velocity time integral occurring at the sampling site and the effective systolic AV orifice area (AVOA eff ). Nevertheless, a generally accepted method for the determination of AVOA eff is still lacking. Methods: Aortic valve OA eff was measured in 228 consecutive patients scheduled for coronary artery surgery. Two widely adopted methods were applied to approximate the constantly changing orifice area of the AV: (1) the circular orifice model (AVOA–CM), and (2) the triangular orifice model (AVOA–TM). Aortic valve OA–CM assumes the shape of a circle as an appropriately time averaged geometrical model, and AVOA–TM takes the shape of an equilateral triangle for granted. Results: The AV was easily imaged by echocardiography in both short‐ and long‐axis views in all patients. Relying on AVOA–CM, AVOA eff was 3.49 ± 0.77 cm 2 . AVOA–TM estimates were 2.80 ± 0.55 cm 2 (mean ± SD). The results did not agree (bias analysis). Conclusions: The echocardiographic measurement of SV or CO at the level of the AV has to be reconsidered.