Gueret P, Vignon P, Fournier P, Chabernaud J M, Gomez M, LaCroix P, Bensaid J
Department of Cardiology, University Hospital Dupuytren, Limoges, France.
Circulation. 1995 Jan 1;91(1):103-10. doi: 10.1161/01.cir.91.1.103.
Diagnosis of a mechanical mitral valve prosthesis thrombosis is currently made with transthoracic Doppler echocardiography and occasionally with fluoroscopy. However, identifying a thrombus on a valve prosthesis may be difficult, especially if the thrombus is nonobstructive. To prospectively define the role of transesophageal echocardiography for identification of nonobstructive thrombi, we studied a series of patients in whom the prosthetic valve was considered to function normally on clinical examination and transthoracic echocardiography.
One hundred fourteen consecutive patients with mechanical mitral valve prosthesis were investigated by both transthoracic echocardiography and transesophageal echocardiography. These examinations were performed for recent systemic emboli (15 patients), fever of unknown etiology (11 patients), routine postoperative evaluation (56 patients), and other reasons (32 patients). Based on transthoracic echo diagnosis, all prostheses were considered normal. Yet, in 20 patients transesophageal echocardiography revealed the presence of a 2- to 15-mm-long mobile thrombus localized on the atrial surface of the prosthesis. When compared with the remaining 94 patients with no visible thrombi, there was no significant difference between the two groups in terms of incidence of atrial fibrillation (65% versus 52%), left atrial size (48 +/- 9 versus 51 +/- 13 mm), left ventricular end-diastolic diameter (49 +/- 10 versus 51 +/- 13 mm) and fractional shortening (28 +/- 9% versus 31 +/- 10%), presence of spontaneous contrast to the left atrium (40% versus 41%), transprosthetic mean pressure gradient (4.0 +/- 1.4 versus 3.9 +/- 1.5 mm Hg), or the type of prosthesis used. After we discovered a nonobstructive thrombosis, patients were treated with heparin (n = 9) or oral anticoagulation (n = 11). The presence of a localized thrombus was confirmed in 3 patients who were operated on. In the present study, evolution appeared to depend on thrombus size: of 14 patients exhibiting a small (< 5 mm) thrombus, 10 had an uneventful course, whereas 5 of 6 patients with a large (> or = 5 mm) thrombus developed complications or died.
Transesophageal echocardiography appears to be a reliable method to diagnose thrombi on a mechanical mitral valve prosthesis, even when transthoracic Doppler echocardiographic parameters appear to be normal. Transesophageal echo assessment of thrombus size may be helpful in deciding whether a patient with mitral prosthesis should be treated by anticoagulation, thrombolysis, or valve rereplacement.
目前机械二尖瓣人工瓣膜血栓形成的诊断主要依靠经胸多普勒超声心动图，偶尔也会用到荧光镜检查。然而，在人工瓣膜上识别血栓可能很困难，尤其是当血栓未造成梗阻时。为前瞻性地确定经食管超声心动图在识别非梗阻性血栓方面的作用，我们对一系列临床检查和经胸超声心动图显示人工瓣膜功能正常的患者进行了研究。
连续114例机械二尖瓣人工瓣膜患者接受了经胸超声心动图和经食管超声心动图检查。这些检查是因近期全身性栓塞（15例）、不明原因发热（11例）、常规术后评估（56例）及其他原因（32例）而进行的。基于经胸超声心动图诊断，所有人工瓣膜均被认为正常。然而，20例患者经食管超声心动图显示在人工瓣膜心房面存在2至15毫米长的活动血栓。与其余94例未见血栓的患者相比，两组在房颤发生率（65%对52%）、左心房大小（48±9对51±13毫米）、左心室舒张末期直径（49±10对51±13毫米）和缩短分数（28±9%对31±10%）、左心房自发显影的存在情况（40%对41%）、跨人工瓣膜平均压力阶差（4.0±1.4对3.9±1.5毫米汞柱）或所用人工瓣膜类型方面无显著差异。在发现非梗阻性血栓形成后，患者接受了肝素治疗（9例）或口服抗凝治疗（11例）。3例接受手术的患者术中证实存在局限性血栓。在本研究中，病情演变似乎取决于血栓大小：14例血栓较小（<5毫米）的患者中，10例病情平稳，而6例血栓较大（≥5毫米）的患者中有5例出现并发症或死亡。
经食管超声心动图似乎是诊断机械二尖瓣人工瓣膜血栓的可靠方法，即使经胸多普勒超声心动图参数看似正常。经食管超声心动图对血栓大小的评估可能有助于决定二尖瓣人工瓣膜患者应接受抗凝、溶栓还是瓣膜置换治疗。
