Important pressure recovery in patients with aortic stenosis and high Doppler gradients

Pressure recovery has been described in aortic stenosis and may explain the difference occasionally observed between Doppler- and catheter-measured gradients. A narrow ascending aorta (AA) and moderately severe stenosis favors pressure recovery. The aims of this study were to investigate the degree to which these conditions are present in patients with aortic stenosis and high Doppler gradients and to evaluate the magnitude of pressure recovery. One hundred sixteen patients were examined with Doppler echocardiography before aortic valve replacement. Patients with a maximum gradient >70 mm Hg (n = 81) were included. The diameter of the AA was measured and compared with the diameter in an age- and body size-matched group of normal controls (n = 23). Pressure recovery was estimated from a previously validated equation by measuring the maximum Doppler gradient, the effective orifice area (EOA), and the diameter of the AA. The diameter of the AA was similar for patients (mean 3.0 cm, range 2.1 to 4.1) and normal controls (mean 3.0 cm, range 2.3 to 3.5). The maximum Doppler gradient was 107 mm Hg (range 71 to 170) and the EOA was 0.6 cm(2) (range 0.2 to 1.3). The calculated pressure recovery was 18 mm Hg (range 6 to 37), which gives a net gradient of 89 mm Hg (range 51 to 151). Twenty-three percent had a net gradient <70 mm Hg. A cutoff of EOA/AA diameter at >0.2 cm identified 84% of patients (16 of 19) with a net gradient <70 mm Hg. In conclusion, we found that important pressure recovery can be expected in most patients with aortic stenosis and high Doppler gradients. Pressure recovery may explain why some patients with high Doppler gradients are asymptomatic. Also, pressure recovery is a factor to consider in patients with atypical symptomatology and high Doppler gradients when one must decide on valvular replacement.