Clinical application of the continuity equation to calculate aortic valve area is confounded by difficulties to obtain a satisfactory left ventricular outflow tract (LVOT) velocity (VLVOT). Recent work suggests that the transaortic continuous wave Doppler (CW) trace frequently has a second lower velocity waveform (V1) reflecting LVOT velocity. The aim of present study was to determine whether V1, by CW equals the required VLVOT by pulsed wave Doppler (PW) trace.

Author compared V1, by CW with VLVOT by PW in 47 patients with rheumatic aortic valve stenosis (AS), 102 patients with degenerative AS, 31 patients with bicuspid AS and 25 patients with aortic valve replacement.

The differences between V1 by CW and VLVOT, by PW (VLVOT- V1) were 1.0±6.0 cm/sec, -1.4±6.1 cm/sec, -4.5±7.4 cm/sec and 0.9±6.7 cm/sec in patients with rheumatic AS, degenerative AS, bicuspid AS and aortic valve replacement, respectively. The percent differences between V, by CW and V1 by PW (V1/VLVOT) were 99.1±5.0%, 101.3±5.8%, 104.6±6.7% and 100.7±6.2% in patients with rheumatic AS, degenerative AS, bicuspid AS and aortic valve replacement, respectively, The good correlation were found when V1, were compared with VLVOT in patients with rheumatic AS (r=0.951, p=0.000), degenerative AS (r=0.954, p=0.000), bicuspid AS (r=0, 970, p=0.000) and aortic valve replacement (r=0.951, p=0,000). The results suggests that V1 by CW approximately equaled to VLVOT in groups of patients with AS.

The results indicate that the valve area in patients with AS can be reliably estimated noninvasively by the simplified equation of continuity based on the aortic valve double spectral envelope.