Stress echocardiography in differentiation of fixed vs. low flow-low gradient and pseudo severe aortic stenosis

To present the importance of stress echocardiography in diagnosis of low flow-low gradient aortic stenosis (AS).

Two patients were tested, one male patient, aged 62, weight 72 kg, height 172 cm, and BSA 1.86 cm2, and the other one was female, aged 59, weight 83 kg, height 168 cm and BSA, were found to have at least moderate ASs with low flow and low gradients at rest. Dobutamine stress test was performed using standard protocol starting at 2.5 mcg/kg/min at rest as continuous infusion and increasing every five minutes intervals with stepwise increase up to 20 mcg/kg/min. Monitoring with 12-lead ECG and blood pressure measurements at each step was performed. After completing the test, transthoracic echocardiography (TTE) showed in male patient increasing in transvalvular flow and gradients across aortic valve and ejection fraction (EF) measured by Simpson method increased from 33% at rest up to 40% following Dobutamine administration. EOA (effective aortic valve area) from 0.8 cm2 at rest increased insignificantly to 0.85 cm, (0.425 m2) afterwards.

Final diagnosis therefore was severe aortic stenosis with preserved contractile reserve. The patient was scheduled for surgical valve replacement. In female patient after DST, the area of aortic valve increased significantly from 0.75 cm2 up to 1.05 cm2, while all transvalvular gradients remained almost unchanged. Pseudo-Aortic Stenosis and surgical valve replacement had not been indicated at this time.