Schnitz Benjamin A, Guan Dong Xu, Malkin Robert A
Joint Program for Biomedical Engineering, The University of Memphis, Memphis, TN 38152, USA.
IEEE Trans Biomed Eng. 2004 Feb;51(2):355-61. doi: 10.1109/TBME.2003.820388.
While there is extensive mapping of the spread of electrical activity in the heart, there have been no measurements of electrical and localized mechanical, or contractile, activity. Yet the development of effective treatments for diseases like chronic heart failure and cardiac hypertrophy depend on the ability to quantify improvements in electrocontractile function. In this paper, we present a sensor that is capable of making simultaneous, electrocontractile measurements. Its small size facilitates placement in multiple myocardial sites for multichannel studies. Semiconductor strain gages are used for force sensing, and Ag/AgCl-plated tungsten electrodes act as electrogram sensors. The sensor contains electronics on-board, including instrumentation amplifiers and a microprocessor for data sampling and analog-to-digital conversion. Each sensor can accurately detect 0-245+/-5 mV in two electrogram channels with a sensitivity of 0.96+/-0.2 mV/step and less than 2% error, and 0-144+/-29 g of contractile force with a sensitivity of 0.56+/-0.11 g/step in the analog-to-digital conversion and less than 6% error. The sensor has been tested in vivo in open-chest rabbit and pig mapping studies. These studies indicated that the average peak-to-peak contractile force at the apex is smaller in the rabbit than the pig (13.3 versus 40.3 g), that the average peak-to-peak contractile force in the pig is smaller near the base than near the apex (31.3 versus 40.3 g), and that contractile force is visibly decreased during ventricular fibrillation compared to normal sinus rhythm.
虽然对心脏电活动的传播已有广泛的测绘，但尚未对电活动与局部机械活动（即收缩活动）进行测量。然而，针对慢性心力衰竭和心肌肥大等疾病开发有效的治疗方法，依赖于量化电收缩功能改善情况的能力。在本文中，我们展示了一种能够同时进行电收缩测量的传感器。其小尺寸便于放置在多个心肌部位进行多通道研究。半导体应变片用于力传感，镀有Ag/AgCl的钨电极用作心电信号传感器。该传感器内置电子元件，包括仪表放大器和用于数据采样及模数转换的微处理器。每个传感器在两个心电信号通道中能准确检测0 - 245±5 mV，灵敏度为0.96±0.2 mV/步，误差小于2%；在模数转换中能检测0 - 144±29 g的收缩力，灵敏度为0.56±0.11 g/步，误差小于6%。该传感器已在开胸兔和猪的体内测绘研究中进行了测试。这些研究表明，兔心尖处的平均峰 - 峰值收缩力小于猪心尖处（13.3 g对40.3 g），猪心底附近的平均峰 - 峰值收缩力小于心尖附近（31.3 g对40.3 g），且与正常窦性心律相比，心室颤动期间收缩力明显降低。
