Application of Doppler Flow Mapping in Assessing the Severity of Mitral Stenosis

The purpose of the flow mapping procedure is to pick up flow signals related to jets at the site of lesions, in order to delineate the cross-section of the jets. The pulsed Doppler procedure was applied to a group of 33 consecutive patients with mitral stenosis confirmed invasively in all cases and by surgery in 15 cases. The examination involved the recording of flow signals at the distal edge of the mitral oriface investigated in the short-axis view. Doppler criteria for required flow signals were the presence of a high-pitched tone and of a laminar spectrum, occurring at a definite timing in early to mid-diastole, i.e. at the period of the maximal atrioventricular pressure gradient. Planimetry of the flow area was performed and correlated with haemodynamic data using the Gorlin formula. The procedure was applicable in 32/33 patients. The correlation coefficient was 0.94, standard error of estimate 0.13 cm2, P less than 0.001. The mean difference between invasive and non-invasive measurements was -0.04 +/- 0.14 cm2 and the standard error of the mean 0.03 cm2. This new application of flow mapping provided reliable information for the later surgical procedure. It should benefit in future from improvements in spatial resolution and in signal to noise ratio.