Min X, Mehra R
Medtronic, Minneapolis, MN 55432, USA.
Prog Biophys Mol Biol. 1998;69(2-3):353-86. doi: 10.1016/s0079-6107(98)00015-7.
In order to optimize defibrillation electrode systems for ventricular defibrillation thresholds (DFTs), a Finite Element Torso model was built from fast CT scans of a patient who had large cardiac dimensions (upper bound of normal) but no heart disease. Clinically used defibrillation electrode configurations, i.e. Superior Vena Cava (SVC) to Right Ventricle (RV) (SVC-RV), left pectoral Can to RV (Can-RV) and Can + SVC-RV, were analyzed. The DFTs were calculated based on 95% ventricular mass having voltage gradient > 5 V/cm and these results were also compared with clinical data. The low voltage gradient regions with voltage gradient < 5 V/cm were identified and the effect of electrode dimension and location on DFTs were also investigated for each system. A good correlation between the model results and the clinical data supports the use of Finite Element Analysis of a human torso model for optimization of defibrillation electrode systems. This correlation also indicates that the critical mass hypothesis is the primary mechanism of defibrillation. Both the FEA results and the clinical data show that Can + SVC-RV system offers the lowest voltage DFTs when compared with SVC-RV and Can-RV systems. Analysis of the effect of RV, SVC and Can electrode dimensions and locations can have an important impact on defibrillation lead designs.
为了优化用于心室除颤阈值（DFT）的除颤电极系统，利用一位心脏尺寸较大（处于正常范围上限）但无心脏病患者的快速CT扫描构建了有限元人体躯干模型。分析了临床使用的除颤电极配置，即上腔静脉（SVC）至右心室（RV）（SVC - RV）、左胸电极至RV（电极 - RV）以及电极 + SVC - RV。基于95%心室质量的电压梯度>5 V/cm计算DFT，并将这些结果与临床数据进行比较。识别出电压梯度<5 V/cm的低电压梯度区域，并针对每个系统研究电极尺寸和位置对DFT的影响。模型结果与临床数据之间的良好相关性支持使用人体躯干模型的有限元分析来优化除颤电极系统。这种相关性还表明临界质量假说是除颤的主要机制。有限元分析结果和临床数据均表明，与SVC - RV和电极 - RV系统相比，电极 + SVC - RV系统的除颤阈值电压最低。分析RV、SVC和电极的尺寸及位置效应可能对除颤导线设计产生重要影响。
