Transesophageal echocardiographic evaluation of native aortic valve area: Utility of the double-envelope technique

Objective: To assess the accuracy of aortic valve area (AVA) calculations u sing the continuity equation with data obtained from the double envelope (D E) (simultaneously obtained left ventricular outflow tract [V-1]) and aorti c valve [V-2] velocities) during intraoperative transesophageal echocardiog raphy (IEE). Design:Prospective study; measurements were performed on-line. Setting: University hospital. Participants:Cardiac and noncardiac surgical patients (n = 75) with recent aortic valve assessment (<3 months) undergoing general anesthesia or endotr acheal intubation. Interventions: Intraoperative AVA was measured by the continuity equation u sing the DE technique (DE/TEE) and by planimetry (PL/TEE). Left ventricular outflow tract diameter was obtained from midesophageal views, whereas subv alvular (V-1) and valvular (V-2) velocities were obtained simultaneously us ing continuous-wave Doppler from transgastric views. V-1 was also obtained using pulsed-wave Doppler. Measurements were compared with AVA obtained pre operatively by the Gorlin equation during cardiac catheterization (G/CATH) or by transthoracic echocardiography using the traditional continuity equat ion (C/TTE) (nonsimultaneously obtained V-1 and V-2) Measurements and Main Results: A DE was obtained in 73 of 75 patients (97%) . Four patients had atrial fibrillation at the time of the examination, whe reas the rest were in sinus rhythm. PL/TEE was performed in 54 of 71 patien ts with sinus rhythm (76%). Agreement was good between DE/TEE and G/CATH (m ean bias, 0.02 cm(2) [SD, 0.24 cm(2)]), and C/TTE (mean bias, -0.05 cm(2) [ SD, 0.16 cm(2)]). Agreement was not as good between PL/TEE and G/CATH (mean bias, -0.07 cm(2) [SD, 0.28 cm(2)]) and C/TTE (mean bias, -0.13 cm(2) [SD, 0.30 cm(2)]). V-1 obtained by pulsed-wave Doppler and with DE closely agre ed (mean bias, 0.01 m/sec [SD, 0.05 m/sec]). Conclusion: TEE evaluation of native AVA using the DE technique is feasible and in good agreement with that obtained by C/TTE and G/CATH. Compared wit h DE/TEE, PL/ TEE did not agree as well. Use of DE/TEE should simplify the continuity equation and may minimize errors resulting from beat-to-beat var iability in stroke volume. Copyright (C) 2001 by W.B. Saunders Company.