Thromboembolism after percutaneous balloon mitral valvotomy (PBMV) has been attributed to dislodgment of preexisting thrombus during transseptal puncture and instrumentation of the left atrium. The occurrence of thromboembolic events after PBMV in the absence of demonstrable left atrial thrombus before PBMV suggests that thrombus might form during the procedure. Spontaneous echo contrast (SEC) is a swirling pattern of blood echogenicity that is a marker of blood stasis in the left atrium. Exacerbation of left atrial SEC during PBMV may be indicative of an increased thromboembolic risk.Methods
Transesophageal echocardiography was performed during PBMV in 20 patients with mitral stenosis. Grades of severity of left atrial SEC [0 (nil) to 4+(severe)] were allocated before and after each balloon inflation.Results
Before PBMV, SEC was present in 17 patients. New SEC or increased severity of SEC was observed during 49 of 56 balloon inflations. SEC was unchanged after six deflations, decreased after 14 deflations, and disappeared after 36 deflations. The mean times to onset and dissipation of SEC after balloon inflation and deflation were 3.1 ± 1.5 and 3.9 ± 1.6 seconds, respectively. After successful PBMV, SEC was unchanged in three patients, decreased in one, and resolved in 13.Conclusions
SEC is a dynamic and acutely reversible phenomenon that is highly sensitive to changes in left atrial hemodynamic conditions. Left atrial blood stasis induced by balloon inflation may promote thrombogenesis during PBMV.