Chen P S, Feld G K, Kriett J M, Mower M M, Tarazi R Y, Fleck R P, Swerdlow C D, Gang E S, Kass R M
Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048.
Circulation. 1993 Jul;88(1):186-92. doi: 10.1161/01.cir.88.1.186.
In the canine model, an upper limit of shock strength exists that can induce ventricular fibrillation during the vulnerable period of the cardiac cycle. This shock strength (the upper limit of vulnerability) closely correlates with the defibrillation threshold and supports the "upper limit of vulnerability" hypothesis of defibrillation. It is not known whether an upper limit of vulnerability exists in humans or whether this limit correlates with the defibrillation threshold.
In 13 patients undergoing implantable cardioverter-defibrillator implantation, the shock strengths associated with a 50% probability of reaching the upper limit of vulnerability (ULV50) and a 50% probability of reaching the defibrillation threshold (DFT50) were determined by the up-down algorithm. The ULV50 was determined only for the mid-upslope of the positive T waves and for the mid-downslope of the negative T waves. No major complications occurred during surgery. An upper limit of vulnerability was demonstrated in each patient. The ULV50 was 300 +/- 138 V or 6.8 +/- 5.8 J, which was significantly lower than the DFT50 of 347 +/- 167 V (p = 0.038) or 9.1 +/- 7.3 J (p = 0.013). The correlation between the ULV50 and the DFT50 was significant (r = 0.90, p < 0.001 for voltage; r = 0.93, p < 0.001 for energy).
An upper limit of vulnerability is present in humans. There is a significant correlation between the ULV50 and the DFT50, and the ULV50 is significantly lower than the DFT50.
在犬类模型中，存在一个休克强度上限，在心动周期的易损期可诱发心室颤动。这种休克强度（易损性上限）与除颤阈值密切相关，并支持除颤的“易损性上限”假说。目前尚不清楚人类是否存在易损性上限，以及该上限是否与除颤阈值相关。
在13例接受植入式心脏复律除颤器植入的患者中，通过上下算法确定达到易损性上限（ULV50）50%概率和达到除颤阈值（DFT50）50%概率时的休克强度。仅在正向T波的上升支中点和负向T波的下降支中点测定ULV50。手术期间未发生重大并发症。在每位患者中均证实存在易损性上限。ULV50为300±138V或6.8±5.8J，显著低于DFT50的347±167V（p = 0.038）或9.1±7.3J（p = 0.013）。ULV50与DFT50之间的相关性显著（电压方面r = 0.90，p < 0.001；能量方面r = 0.93，p < 0.001）。
人类存在易损性上限。ULV50与DFT50之间存在显著相关性，且ULV50显著低于DFT50。
