Schöndube F, Keusen H, Messmer B J
J Thorac Cardiovasc Surg. 1983 Jul;86(1):136-41.
The closing sound of an implanted Björk-Shiley heart valve prosthesis can be heard clearly in the proximity of the patient. A clinical interrogation of 35 patients showed that 16 (46%) were disturbed by the clicking noise and 10 (29%) reported disturbance of those nearby. A silent prosthesis would be preferred by 15 (43%) patients, eight (23%) declined such a valve for reasons of their own security, and 12 (34%) patients were undecided. The frequency spectrum of the metallic closing sound and its loudness were measured by noninvasive techniques in 20 patients. In the aortic as well as in the mitral position, a high peak of the sound pressure level was registered at 9.8 kHz. In 20 patients the average value of the sound pressure level was 35 dbA measured at a distance of 10 cm from the patient's chest. In vitro studies demonstrated a high peak of the sound pressure level at 9.5 kHz for the Björk-Shiley valve when recorded in free air and at 7 kHz in a standardized valve chamber of a mock circulatory system filled with blood or water. A decrease of the sound pressure level could be achieved by a textile wrap around the chest which damps frequencies around 10 kHz. This protects those nearby but not the patient, who hears the clicking mainly through internal conduction. This unpleasant valve noise can be eliminated only during construction of a new prosthesis provided that such "minor" side effects are measured and taken into consideration.
在患者附近能够清晰听到植入的比约克-希利心脏瓣膜假体的关闭声音。对35名患者进行的临床询问显示，16名（46%）患者受到咔嗒声干扰，10名（29%）患者报告附近的人受到干扰。15名（43%）患者更喜欢无声假体，8名（23%）患者出于自身安全原因拒绝使用这种瓣膜，12名（34%）患者尚未决定。通过无创技术对20名患者的金属关闭声音的频谱及其响度进行了测量。在主动脉和二尖瓣位置，在9.8千赫处记录到声压级的一个高峰。在20名患者中，在距患者胸部10厘米处测得的声压级平均值为35分贝A。体外研究表明，比约克-希利瓣膜在自由空气中记录时，声压级在9.5千赫处有一个高峰，在充满血液或水的模拟循环系统的标准化瓣膜腔中，在7千赫处有一个高峰。通过在胸部周围包裹织物可以降低声压级，该织物可衰减10千赫左右的频率。这能保护附近的人，但保护不了患者，因为患者主要通过内部传导听到咔嗒声。只有在制造新的假体时才能消除这种令人不快的瓣膜噪音，前提是要测量并考虑到这种“轻微”的副作用。
