Deklunder G, Lecroart J L, Savoye C, Coquet B, Houdas Y
Cardiology Hospital, University of Lille, France.
J Heart Valve Dis. 1996 Nov;5(6):662-7.
In preceding studies, we reported that abnormal Doppler signals of high intensity (HITS) were frequently found in the cerebral arteries of patients with prosthetic mechanical heart valves. These signals should be attributed either to air microbubbles, possibly due to cavitations or to solid emboli elements. On the other hand, the presence of abnormal intracardiac echoes has been reported in patients with mechanical valves. These echoes should be also attributed to air microbubbles or to formed elements. Although in vitro experiments are in favor of the first explanation, the discussion of their origin remains open.
Among patients subjected to a transesophageal echocardiography (TEE), we selected subjects with mechanical prosthetic heart valves, according to the following criteria: (i) normally functioning valves; (ii) bright echoes suggesting microbubbles, inside the prosthetic valve and/or upstream from it (left ventricular outflow tract or left atrium); (iii) no morphological lesions that could generate solid microemboli at the prosthetic level; (iv) normal carotid arteries, as investigated by color echo-Doppler.
Twenty patients were selected: 11 men and nine women of age range 40-64 years. They were implanted with mechanical heart valves (24 Saint-Jude Medical, three Björk-Shiley and one CarboMedics) in the mitral position (10), aortic position (two), or mitral and aortic position (eight) for periods ranging from 10 days to 17 years. There was no major left ventricular dysfunction (mean end-diastolic diameter 51.8 mm; mean ejection fraction 59%). The mean diameter of the left atrium was 46.1 mm. All but three patients were in sinus rhythm; seven had presented with a transient ischemic attack or amaurosis within the six months preceding the investigation. Immediately after TEE, Doppler signals were recorded on the middle cerebral arteries (MCA) during 10 minutes on each side, and the abnormal Doppler signals were counted. Seventeen subjects (85%) exhibited HITS repetition rate from 0.2 to 5.5 per min.
The percentage of patients with HITS in a non-selected group with mechanical heart valves was about 50%, as observed in previous studies. It appears that in a selected group of patients the percentage with HITS is consistently higher. Therefore, HITS and abnormal intracardiac echoes could have a common origin.
在先前的研究中，我们报告称，在人工机械心脏瓣膜患者的脑动脉中经常发现高强度异常多普勒信号（HITS）。这些信号应归因于空气微泡，可能是由于空化作用，也可能归因于固体栓子成分。另一方面，有报道称机械瓣膜患者存在心脏内异常回声。这些回声也应归因于空气微泡或形成的成分。尽管体外实验支持第一种解释，但其起源的讨论仍未定论。
在接受经食管超声心动图（TEE）检查的患者中，我们根据以下标准选择了人工机械心脏瓣膜患者：（i）瓣膜功能正常；（ii）人工瓣膜内部和/或其上游（左心室流出道或左心房）有提示微泡的明亮回声；（iii）在人工瓣膜水平没有可产生固体微栓子的形态学病变；（iv）经彩色超声多普勒检查颈动脉正常。
共选择了20例患者：11名男性和9名女性，年龄在40 - 64岁之间。他们在二尖瓣位置（10例）、主动脉位置（2例）或二尖瓣和主动脉位置（8例）植入了机械心脏瓣膜（24个圣犹达医疗瓣膜、3个 Björk-Shiley瓣膜和1个 Carbomedics瓣膜），植入时间从10天到17年不等。没有严重的左心室功能障碍（平均舒张末期直径51.8毫米；平均射血分数59%）。左心房平均直径为46.1毫米。除3例患者外，其余均为窦性心律；7例患者在检查前6个月内曾出现短暂性脑缺血发作或黑矇。TEE检查后立即在两侧大脑中动脉（MCA）上记录10分钟的多普勒信号，并对异常多普勒信号进行计数。17名受试者（85%）的HITS重复率为每分钟0.2至5.5次。
如先前研究中所观察到的，在未选择的人工机械心脏瓣膜患者组中，出现HITS的患者百分比约为50%。似乎在选定的患者组中，出现HITS的百分比一直较高。因此，HITS和心脏内异常回声可能有共同的起源。
