Echt Debra S, Cowan Mark W, Riley Richard E, Brisken Axel F
EBR Systems, Inc., Sunnyvale, California 94085, USA.
Heart Rhythm. 2006 Oct;3(10):1202-6. doi: 10.1016/j.hrthm.2006.06.012. Epub 2006 Jul 7.
Pacemaker lead complications and failures remain clinical problems. New devices incorporating three leads are associated with even greater limitations.
The purpose of this study was to investigate the feasibility and safety of a technology enabling cardiac pacing without leads in an acute porcine model.
The system is composed of an ultrasound transmitter delivering energy from the chest wall to a receiver-electrode in contact with the myocardium that then converts the ultrasound energy to electrical energy sufficient to pace. In five feasibility studies, the receiver-electrodes were attached to the tip of a catheter to facilitate intracardiac positioning at pacing sites. In six safety studies (five treatment and one sham), ultrasound energy was transmitted to both chest walls, and histopathologic examinations were performed to evaluate bioeffects due to ultrasound energy transmission.
In five feasibility studies, direct and ultrasound-mediated electrical pacing was demonstrated at 30 sites in the right atrium, right ventricle, and left ventricle, at direct electrical pacing outputs of 1.4 +/- 0.6 V and ultrasound-mediated electrical pacing outputs of 1.8 +/- 0.9 V. The mechanical index was 0.6 +/- 0.4 at the receiver site during ultrasound-mediated pacing at a depth of 11.2 +/- 2.4 cm from the chest wall. Using two receiver-electrode catheters, biventricular pacing was demonstrated in all studies. In five safety study treatment animals at a similar depth, the peak mechanical index was 2.3, and the thermal index was 0.4. Microscopic evaluation revealed no evidence of mechanical or thermal bioeffects.
The feasibility and safety of this novel technology for pacing without leads has been demonstrated acutely in animals.
起搏器导线并发症和故障仍是临床问题。包含三根导线的新型设备存在更大局限性。
本研究旨在探讨一种在急性猪模型中实现无导线心脏起搏技术的可行性和安全性。
该系统由一个超声发射器组成，其从胸壁向与心肌接触的接收电极传递能量，该接收电极随后将超声能量转换为足以起搏的电能。在五项可行性研究中，接收电极连接到导管尖端以便于在心脏起搏部位进行心内定位。在六项安全性研究（五项治疗性研究和一项假手术研究）中，超声能量被传输到双侧胸壁，并进行组织病理学检查以评估超声能量传输产生的生物效应。
在五项可行性研究中，在右心房、右心室和左心室的30个部位证实了直接和超声介导的电起搏，直接电起搏输出为1.4±0.6V，超声介导的电起搏输出为1.8±0.9V。在距胸壁深度为11.2±2.4cm处进行超声介导起搏时，接收部位的机械指数为0.6±0.4。在所有研究中，使用两根接收电极导管均证实了双心室起搏。在五项安全性研究的治疗动物中，在类似深度处，峰值机械指数为2.3，热指数为0.4。显微镜评估未发现机械或热生物效应的证据。
这种新型无导线起搏技术的可行性和安全性已在动物急性实验中得到证实。
