Kerber R E, Martins J B, Gascho J A, Marcus M L, Grayzel J
Circulation. 1981 Feb;63(2):323-32. doi: 10.1161/01.cir.63.2.323.
Very high energy electrical countershocks can cause morphologic damage to the myocardium. In this study we searched for functional correlates of these shock-induced morphologic changes. We used ultrasonic sonomicrometers to measure myocardial contractility and radiolabeled microspheres to assess perfusion. Acute and chronic experiments were conducted in 45 dogs, assessing the effect of both direct (epicardial) and transthoracic shocks on beating and fibrillating hearts. High-energy or rapidly repeated epicardial shocks caused subepicardial contraction abnormalities. This indicates that electrical current delivered to the myocardium in sufficiently high amounts and concentration can cause functional damage. Thus, in open-chest defibrillation during cardiac surgery, low energies (10-20 J) should be used initially and higher energies resorted to only if lower-energy shocks fail. However, single and multiple transthoracic shocks up to 460 J delivered energy caused no detectable contraction abnormalities. Myocardial perfusion did not fall after shocks. Thus, high-energy transthoracic shocks may have no deleterious effects on the contraction and perfusion of normal myocardium.
极高能量的电击除颤可导致心肌形态学损伤。在本研究中，我们探寻了这些电击诱导的形态学改变的功能相关性。我们使用超声测距仪测量心肌收缩力，并使用放射性微球评估灌注情况。对45只犬进行了急性和慢性实验，评估直接（心外膜）电击和经胸电击对跳动心脏和颤动心脏的影响。高能量或快速重复的心外膜电击会导致心外膜下收缩异常。这表明，以足够高的量和浓度传递到心肌的电流会造成功能损伤。因此，在心脏手术中进行开胸除颤时，应首先使用低能量（10 - 20焦耳），只有在低能量电击失败时才采用更高能量。然而，高达460焦耳的单次和多次经胸电击所传递的能量并未引起可检测到的收缩异常。电击后心肌灌注并未下降。因此，高能量经胸电击可能对正常心肌的收缩和灌注没有有害影响。
