fig9

Figure 9. Two-dimensional transthoracic echocardiography. Apical four-chamber views. A, B: when the NL of 48 cm/s (A) was increased to 80 cm/s (B) without moving the transducer and keeping the color Doppler gain constant at 31, the MR flow signals showed marked reduction in size in this patient with substantial MR; C, D: in another patient with substantial MR, reducing color Doppler gain from 46% (C) to 27% (D) keeping the NL constant at 50 cm/s and not moving the transducer resulted in complete disappearance of MR signals. Color gain is optimized by first increasing it till stationary artifactual echoes often extending beyond the LA walls appear and then decreasing it gradually till they just disappear. LA: left atrium; MR: mitral regurgitation; NL: Nyquist limit; RV: right ventricle; RA: right atrium; LV: left ventricle; MV: mitral valve. Reproduced with permission from Manjunath et al.^[4]