Lee T M, Chou N K, Su S F, Lin Y J, Chen M F, Liau C S, Lee Y T, Chu S H
Department of Internal Medicine, College of Medicine, National Taiwan University, National Taiwan University Hospital, Taipei.
Ann Thorac Surg. 1996 Dec;62(6):1790-5. doi: 10.1016/s0003-4975(96)00739-4.
Valve thromboembolism may be a fatal complication of mechanical valve prosthesis if detected late. Spontaneous echo contrast (SEC) is a well-documented prothrombotic phenomenon; here we report it in asymptomatic patients with a mechanical valve prosthesis.
Ninety-two asymptomatic patients with a mechanical valve prosthesis for underlying rheumatic heart disease underwent transesophageal echocardiography. Appendage area, peak filling and emptying velocities of the left atrial appendage, and the presence or absence of SEC and thrombi were determined. The results of 56 patients without SEC or thrombi (group I) were compared with those of 24 patients with SEC and no thrombi (group II) and 12 patients with thrombi (group III).
Spontaneous echo contrast was present in 39% of the asymptomatic patients with a mechanical valve prosthesis. Although 12 patients had cardiac thrombi, including valve thrombi in 4, no patients presented symptoms. Anticoagulant therapy had no significant association with SEC and atrial thrombi. There was a significantly greater prevalence of atrial fibrillation and mitral prosthesis in groups II and III than in group I. Two patterns of left atrial appendage flow were identified: one was organized biphasic flow with peak filling velocities of 41.2 +/- 17.2 cm/s and emptying velocities of 40.5 +/- 17.5 cm/s. The other showed irregular, very low peak filling velocities (104 +/- 11.5 cm/s) and emptying velocities (12.3 +/- 13.1 cm/s). The former flow pattern was associated with sinus rhythm and the latter form was associated with atrial fibrillation.
There was a relatively high prevalence of SEC and thrombi in patients with a mechanical valve prosthesis. Patients with a valve prosthesis may not have clinical symptoms. Anticoagulation intensity was not associated with the occurrence of SEC and thrombi. Patients with the mitral valve prosthesis and atrial fibrillation were identified as a high-risk of subgroup for the development of SEC and thrombi.
人工机械瓣膜血栓栓塞若发现较晚可能是致命的并发症。自发显影（SEC）是一种有充分文献记载的促血栓形成现象；在此我们报告其在无症状人工机械瓣膜患者中的情况。
92例因风湿性心脏病植入人工机械瓣膜的无症状患者接受了经食管超声心动图检查。测定心房附件面积、左心耳的峰值充盈和排空速度，以及SEC和血栓的有无。将56例无SEC或血栓的患者（I组）的结果与24例有SEC但无血栓的患者（II组）和12例有血栓的患者（III组）的结果进行比较。
39%的无症状人工机械瓣膜患者存在自发显影。虽然12例患者有心脏血栓，其中4例为瓣膜血栓，但无患者出现症状。抗凝治疗与SEC和心房血栓无显著关联。II组和III组心房颤动和二尖瓣置换的患病率显著高于I组。识别出两种左心耳血流模式：一种是有规律的双相血流，峰值充盈速度为41.2±17.2cm/s，排空速度为40.5±17.5cm/s。另一种表现为不规则、极低的峰值充盈速度（10.4±11.5cm/s）和排空速度（12.3±13.1cm/s）。前一种血流模式与窦性心律相关，后一种模式与心房颤动相关。
人工机械瓣膜患者中SEC和血栓的患病率相对较高。人工瓣膜患者可能没有临床症状。抗凝强度与SEC和血栓的发生无关。二尖瓣置换和心房颤动患者被确定为发生SEC和血栓的高危亚组。
