EARLY TRANSESOPHAGEAL ECHOCARDIOGRAPHY AFTER MITRAL-VALVE REPLACEMENT - SIGNIFICANCE OF SMALL ABNORMAL PROSTHETIC ECHOES

The aim of this study was to determine the frequency, significance and prognosis of small, abnormal, strand-like echos observed by early transoesophageal echocardiography after mitral mechanical valve replacement with hemi-disc prostheses. One hundred and twenty nine consecutive patients operated between October 1988 and June 1992 underwent transoesophageal echocardiography on average 15 +/- 7 days after surgery. A second transoesophageal echocardiography was performed in 52 patients on average 8 months after the first postoperative examination. The frequency of small strand-like echos and of non-obstructive thromboses of the valve at the initial transoesophageal examination was 43 % and 8.5 % respectively. A multivariate analysis showed that the only independant predictive factor for prosthetic valve strands was spontaneous intra-atrial contrast (p < 0.01). The presence of strands was significantly related to the prevalence of early thrombo-embolic events (confirmed non-obstructive valve thrombosis and systemic embolism). Strands were observed in 80 % of cases with early thromboembolic complications compared with only 38 % of cases with no early thromboembolic events (p < 0.04). Univariate analysis showed that the protamine/heparin ratio at the end of cardiopulmonary bypass and the percentage of ineffective postoperative heparinisation were higher in patients with these small, abnormal echos (p < 0.05 and p < 0.001, respectively). These appearances disappear at long-term transoesophageal echocardiographic control examinations in about half the cases. The authors conclude that the majority of these small, abnormal echos are thrombotic in nature and are associated with a higher thromboembolic risk, justifying effective anticoagulation in the first postoperative hours whenever possible, considering the risk of bleeding. The indications of early postoperative transoesophageal echocardiography should be studied after mitral valve replacement.