Quantification of Aortic Stenosis in Mechanically Ventilated Patients Using Multiplane Transesophageal Doppler Echocardiography

¹ From the Klinik and Poliklinik für Innere Medizin II, University of Regensburg, Germany

Study objectives: To evaluate the feasibility and accuracy of multiplane transesophageal Doppler echocardiographic assessment of the severity of aortic stenosis in mechanically ventilated patients using modified transgastral views of the left ventricular outflow tract and the aortic valve.

Design: A prospective study comparing the results of transesophageal echocardiography (TEE) with transthoracic echocardiography (TTE) and cardiac catheterization.

Setting: A university hospital.

Patients: Twenty-eight American Society of Anesthesiologists class III and IV patients with aortic stenosis undergoing elective cardiac surgery for valve replacement.

Interventions: Intubated and mechanically ventilated patients with aortic stenosis undergoing cardiac surgery for valve replacement were studied by multiplane transesophageal Doppler echocardiography to determine transvalvular pressure gradients (Bernoulli formula) and valve areas (continuity equation). These findings were compared with the respective preoperative data from TTE and cardiac catheterization.

Measurements and results: In 25 of 28 patients (89%), adequate transgastral Doppler recordings of the aortic jet could be obtained. The TEE measurements correlated well with the respective data obtained by TTE (maximal pressure gradient: r=0.93, p<0.0001, mean difference=5.9±5.8 mm Hg [mean±SD]; mean pressure gradient: r=0.91, p<0.0001, mean difference=5.4±4.6 mm Hg; aortic valve area: r=0.97, p<0.0001, mean difference=0.07±0.05 cm²) and cardiac catheterization (n=16) (maximal vs peak-to-peak pressure gradient: r=0.84, p<0.0001, mean difference=10.9±8.8 mmHg; mean pressure gradient: r=0.80, p<0.0002, mean difference=9.7±5.9 mm Hg; aortic valve area: r=0.84, p<0.0001, mean difference=0.1±0.08 cm²).

Conclusion: Multiplane transesophageal Doppler echocardiography offers an alternative approach for assessing the severity of aortic stenosis in mechanically ventilated patients in whom conventional TTE is not feasible.

Key Words: aortic stenosis • critical care • Doppler echocardiography • transesophageal echocardiography

Submitted on September 12, 1997
Accepted on December 15, 1997

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