Durand L G, Langlois Y E, Lanthier T, Chiarella R, Coppens P, Carioto S, Bertrand-Bradley S
Laboratory of Biomedical Engineering, University of Montreal, Quebec, Canada.
Med Biol Eng Comput. 1991 Jul;29(4):373-80. doi: 10.1007/BF02441657.
The influence of the closure of the aortic valve leaflets on a dual-micromanometer Millar catheter is investigated with respect to the power spectrum of the aortic component (A2) of the second heart sound in dogs. The catheter inserted through the aortic valve is used to simultaneously record A2 in the left ventricle and in the aorta and to study the transmission of A2 up to the body surface. Results indicate that the interaction of the valve leaflets with the Millar dual-micromanometer catheter during the closure and vibration of the aortic valve does not produce a clapping artefact. The main effect is a change in the natural modes of vibration (resonant frequencies) of the aortic valve resulting from a modification of the vibrating structure (combined structure composed of the catheter, the aortic valve and the surrounding blood and tissues) because of the tight mechanical coupling between the aortic valve leaflets and the catheter. In addition, this modification of the natural modes of resonance does not invalidate the estimation of the frequency response of the transfer function between the aortic root and the thoracic recording site, even if the mean gain of the transfer function is affected and the phase slightly increased with frequency. On the contrary, the interaction of the aortic valve leaflets with the catheter seems to slightly increase the spectral contribution (coherence) of the intra-aortic A2 to the thoracic A2.
关于犬第二心音主动脉成分（A2）的功率谱，研究了主动脉瓣叶关闭对双微压计Millar导管的影响。通过主动脉瓣插入的导管用于同时记录左心室和主动脉中的A2，并研究A2向体表的传导。结果表明，在主动脉瓣关闭和振动过程中，瓣叶与Millar双微压计导管的相互作用不会产生拍击伪影。主要影响是由于主动脉瓣叶与导管之间紧密的机械耦合，导致振动结构（由导管、主动脉瓣以及周围血液和组织组成的复合结构）发生改变，从而使主动脉瓣的固有振动模式（共振频率）发生变化。此外，这种固有共振模式的改变并不会使对主动脉根部与胸部记录部位之间传递函数频率响应的估计无效，即使传递函数的平均增益受到影响且相位随频率略有增加。相反，主动脉瓣叶与导管的相互作用似乎会使主动脉内A2对胸部A2的频谱贡献（相干性）略有增加。
