Enhancement of mitral regurgitation and normal left atrial color Doppler flow signals with peripheral venous injection of a saccharide-based contrast agent

Objectives. The saccharide ultrasound contrast agent SHU 508 A was used to test the hypothesis that an intravenous, transpulmonary contrast method can enhance color Doppler flow signals in the left atrium in a clinically useful manner. Background. Color Doppler display of mitral regurgiation may be unreliable because of variable signal to noise ratios that are at times poor. Traditional contrast agents enhance color Doppler flow signals in the right heart chambers. This study describes our observation of a recently developed contrast agent, SHU 508 A, capable of pulmonary transit after peripheral venous injection. Methods. Control subjects (n = 10) and patients with suspected mitral regurgitation (n = 23) were studied by color Doppler flow imaging before and after 3-g intravenous doses of SHU 508 A. Reference grading of mitral regurgitation (0 to 3) was formulated from left ventricular angiography. In the four-chamber view of the left atrium, we selected for analysis the systolic frame with the maximal retrograde jet of mitral regurgitation (aliased/blue) and the diastolic frame with the maximal color coding from anterograde pulmonary venous flow (red) for planimetry and for grading the intensity of the color Doppler signal (0 to 5). Results. The score of the color Doppler signal intensity increased by ≥2.5 after 3 g of SHU 508 A (p < 0.001). Flow detection improved, as shown by the increased jet area of mitral regurgitation (≥170%), after 3 g of SHU 508 A (3 ± 3 vs. 12 ± 8 cm₂, p < 0.001) and by a ≥200% increase in normal anterograde flow area (p < 0.001) in both the mitral regurgitation group and the control group. After contrsast enhancement, the correlation between angiography grading and the relation of jet area to the left atrial area increased from r = 0.79 to r = 0.91. Conclusions. Contrast-mediated incresed echogenicity of the left atrial blood pool improves the signals to noise ratio of Doppler images of mitral regurgitation and anterograde atrial flow. The technique is safe and simple and seems to minimize variability due to instrument design and anatomic signals attenuation.