Correlation between the position of transducers and mitral valve gradient in mitral stenosis

To assess the severity of mitral stenosis related to the level of transducers, the mitral valve gradient using pulmonary wedge and left ventricle was obtained from 15 patients. The mitral gradient was obtained with both transducers at mid chest level. Then, the level of each transducer was realigned with the catheter tip in the pulmonary capillary wedge and in the left ventricle using lateral fluoroscopy and the mitral gradient was re-measured. At the mid chest level, the mean mitral valve gradient was 14 +/- 6.2 mm Hg with a mitral valve area of 1.3 +/- 0.6 cm2. With the adjusted level of transducers, the mitral valve gradient was 18.7 +/- 6.8 mm Hg with a valve area of 1.0 +/- 0.5 cm2. The difference was that the level of catheter tip in the wedge was 3.5 cm below the mid chest level and the one in the left ventricle was 2.5 cm higher than the mid chest level. This result suggested that the mitral valve gradient obtained at mid chest level underestimated the severity of mitral stenosis.