Andersen Tina S, Johansen Peter, Christensen Bekka O, Paulsen Peter K, Nygaard Hans, Hasenkam J Michael
Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby Sygehus, Aarhus, Denmark.
Ann Thorac Surg. 2006 Jan;81(1):34-41. doi: 10.1016/j.athoracsur.2005.06.080.
Cavitation has been claimed partly responsible for the increased risk of thromboembolic complications, hemolysis, and fatal valve failure seen in mechanical heart valve patients. In vivo studies have investigated cavitation using high-pass filtering of the high-frequency pressure fluctuations with the root mean square values as an assessment of intensities. In vitro studies have shown that this well-known method may not be ideal owing to loss of data as a consequence of filtering, and because it requires a priori knowledge of the valve resonance pattern. Therefore, a new method has been developed, which decomposes the signal into nondeterministic (cavitation) and deterministic (valve resonance) signal components, and hence decreases data loss. This study aimed to evaluate cavitation in patients with mechanical, biological, and native heart valves both intraoperatively and postoperatively using the new method.
High-frequency pressure fluctuations were measured by a hydrophone intraoperatively and postoperatively in 14 patients with mechanical valves, 10 patients with normal aortic valves, and 5 patients with bioprosthesis. The total signal energy was evaluated as nondeterministic and deterministic energies.
Nondeterministic energies were verified both intraoperatively and postoperatively in all patients who had a mechanical valve; this finding confirms the cavitation potential of mechanical valves. None of the data recorded in patients with bioprosthetic or native valves contained nondeterministic energy.
The study confirms the presence of cavitation in mechanical heart valve patients using the nondeterministic energy of high-frequency pressure fluctuations as a quantitative measure of cavitation both intraoperatively and postoperatively.
空化现象被认为是导致机械心脏瓣膜患者血栓栓塞并发症、溶血和致命性瓣膜故障风险增加的部分原因。体内研究通过对高频压力波动进行高通滤波，并以均方根值作为强度评估来研究空化现象。体外研究表明，由于滤波导致数据丢失，且该方法需要瓣膜共振模式的先验知识，这种广为人知的方法可能并不理想。因此，开发了一种新方法，该方法将信号分解为非确定性（空化）和确定性（瓣膜共振）信号成分，从而减少数据丢失。本研究旨在使用新方法评估机械瓣膜、生物瓣膜和天然心脏瓣膜患者术中及术后的空化现象。
在14例机械瓣膜患者、10例正常主动脉瓣患者和5例生物瓣膜患者中，术中及术后使用水听器测量高频压力波动。总信号能量被评估为非确定性和确定性能量。
所有机械瓣膜患者术中及术后均证实存在非确定性能量；这一发现证实了机械瓣膜的空化潜力。生物瓣膜或天然瓣膜患者记录的数据均不包含非确定性能量。
本研究通过将高频压力波动的非确定性能量作为术中及术后空化的定量指标，证实了机械心脏瓣膜患者存在空化现象。
