The effect of transient balloon occlusion of the mitral valve on left atrial appendage blood flow velocity and spontaneous echo contrast

Background: Spontaneous echo contrast (SEC) is a phenomenon that is commonl y seen in areas of blood stasis. It is a slowly moving, cloud-like swirling pattern of "smoke" or increased echogenicity recorded on echocardiography. SEC is commonly seen in the left atrium of patients with mitral stenosis o r atrial fibrillation. The prescence of SEC has been shown to be a marker o f increased thromboembolic risk. Hypothesis: By using transesophageal echocardiography during per cutaneous balloon mitral valvotomy (PBMV), the study investigated the relationship be tween SEC and varying left atrial appendage (LAA) blood now velocity in the human heart. Methods: Thirty-five patients with rheumatic mitral stenosis underwent perc utaneous balloon mitral valvotomy with intraoperative transesophageal echoc ardiography monitoring. We alternatively measured LAA velocities and observ ed the left atrium for various grades of SEC (0 = none to 4 = severe) befor e and after each balloon inflation. Results: Left atrial appendage maximal ejection velocity was reduced from 3 5 +/- 14 to 6 +/- 2 mm/s at peak balloon inflation acid increased to 40 +/- 16 mm/s after balloon deflation. In comparison with the values before ball oon inflation and after balloon deflation, LAA velocities were significantl y lower (p < 0.001). New or increased SEC grade was observed during 54 of 6 1 (88%) inflations and unchanged in 7 (12%) inflations at peak balloon infl ation. Spontaneous echo contrast became lower in grade after 55 balloon def lations (90%), completely disappeared after Is deflations (30%), and remain ed unchanged after 6 deflations (10%). The mean time to achieve maximal SEC grade (2.5 +/- 1.2 s) coincided with the mean time to trough LAA velocitie s (2.3 +/- 1.1 s) after balloon inflation. Upon deflation. the mean time to lowest SEC grade (2.9 +/- 1.8 s) coincided with mean time to achieve maxim al LAA velocities (2.7 +/- 1.6 s). Conclusion: During balloon inflation, the severity of SEC was enhanced with corresponding reduction in LAA flow velocity. Upon balloon deflation, SEC lightens or disappears with increase in LAA flow velocity.