Pharmacodynamic Doppler determination of mitral valve area in patients with significant aortic regurgitation.

In patients with combined mitral stenosis (MS) and aortic regurgitation (AR), the Doppler-determined mitral valve area (MVA) may be overestimated due to a shorter than expected pressure half-time. We performed Doppler echocardiography at baseline and after inhalation of amyl nitrite in 10 patients with combined MS and AR (Group I) and in five patients with MS alone (Group II). AR severity was reduced by amyl nitrite inhalation in all Group I patients, with a decrease in mean jet height/LVOT ratio from 32% to 21% (p < 0.01). Pressure half-time increased in Group I after amyl nitrite, with a mean reduction in the calculated MVA of 0.15 cm2 (p < 0.01). Group II had no significant changes in pressure half-time or Doppler-determined MVA after amyl nitrite, whereas both groups had comparable increases in heart rate, mean transmitral velocity, and mean transmitral pressure gradient. In patients with combined MS and AR, we conclude that amyl nitrite significantly increases pressure half-time while reducing the severity of AR. These findings support earlier reports of MVA overestimation when pressure half-time is used in the presence of AR.