Stockhammer Florian, Miethke Christoph, Knitter Thoralf, Rohde Veit, Sprung Christian
Department of Neurosurgery, Universitätsmedizin Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany,
Acta Neurochir (Wien). 2014 Apr;156(4):761-5. doi: 10.1007/s00701-013-1876-9. Epub 2013 Sep 19.
Noise disturbance arising from the valve is a rare event of ventriculoperitoneal shunts. We queried and investigated shunt patients for occurrence and evaluated the possible factors related to noise development.
Fifty ambulatory patients with implanted proGAV valve were investigated consecutively. Patients were asked for any noise arising from the shunt. In all cases, the valve was auscultated in sitting and upright position. The position of the gravitational unit (GU) was determined in respect to the Frankfurt horizontal plane (FHP) and in head reclination. Ten valves were perfused in vitro at different settings. One valve was opened for video documentation, and a frequency analysis of the noise was performed in nine valves.
Eight percent (4/50) of the patients reported a noise arising from the valve only in upright position in combination with maximum head reclination, and immediately stopped when performing Vasalva's maneuver. In three out of four of these patients, the noise was also audible for the investigator (FS) with a prepared stethoscope. Patients complaining about a noise had a larger GU deviation from vertical during head reclination (median: -80 vs -43°, p = 0.0007, t-test). A deviations threshold of less than -58.4° excluding audible noise by a negative predictive value of 1 (95 % confidence interval [CI] 0.9 to 1.0). In an experimental setting, the noise came from vibrations of the ball in the cone of the adjustable unit and was restricted to a flow of at least 220 ml/h. The noise frequencies tended to be higher at higher opening pressures.
Valve-related noise development may occur in patients with proGAV valves. This event could be prevented during shunt placement by avoiding posterior tilt of the gravitational unit, especially in patients with a good cervical mobility. The noise might indicate transient peak flows and was not associated with clinical or radiological signs of overdrainage.
瓣膜产生的噪声干扰是脑室腹腔分流术罕见的情况。我们对分流患者进行询问并调查噪声的发生情况，并评估与噪声产生相关的可能因素。
连续对50例植入proGAV瓣膜的门诊患者进行调查。询问患者分流装置是否产生任何噪声。所有病例均在坐位和直立位听诊瓣膜。确定重力装置（GU）相对于法兰克福水平面（FHP）的位置以及头部后仰时的位置。在不同设置下对10个瓣膜进行体外灌注。打开一个瓣膜进行视频记录，并对9个瓣膜的噪声进行频率分析。
8%（4/50）的患者报告仅在直立位且头部最大程度后仰时瓣膜产生噪声，在进行瓦尔萨尔瓦动作时立即停止。在这4例患者中的3例中，研究者（FS）用备好的听诊器也能听到噪声。抱怨有噪声的患者在头部后仰时GU与垂直线的偏差更大（中位数：-80°对-43°，p = 0.0007，t检验）。偏差阈值小于-58.4°时，通过阴性预测值1（95%置信区间[CI]0.9至1.0）可排除可闻噪声。在实验环境中，噪声来自可调节装置圆锥体内球的振动，且仅限于至少220 ml/h的流量。在较高的开放压力下，噪声频率往往更高。
proGAV瓣膜患者可能会出现与瓣膜相关的噪声。在分流放置过程中，通过避免重力装置向后倾斜，尤其是对于颈部活动良好的患者，可以预防这种情况。该噪声可能表明短暂的峰值流量，且与过度引流的临床或放射学征象无关。
