Kay Matthew W, Walcott Gregory P, Gladden James D, Melnick Sharon B, Rogers Jack M
Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Am J Physiol Heart Circ Physiol. 2006 Oct;291(4):H1935-41. doi: 10.1152/ajpheart.00276.2006. Epub 2006 Apr 21.
During ventricular fibrillation (VF), electrical activation waves are fragmented, and the heart cannot contract in synchrony. It has been proposed that VF waves emanate from stable periodic sources (often called "mother rotors"). The objective of the present study was to determine if stable rotors are consistently present on the epicardial surface of hearts comparable in size to human hearts. Using new optical mapping technology, we imaged VF from nearly the entire ventricular surface of six isolated swine hearts. Using newly developed pattern analysis algorithms, we identified and tracked VF wave fronts and phase singularities (PS; the pivot point of a reentrant wave front). We introduce the notion of a compound rotor in which the rotor's central PS can change and describe an algorithm for automatically identifying such patterns. This prevents rotor lifetimes from being inappropriately abbreviated by wave front fragmentation and collision events near the PS. We found that stable epicardial rotors were not consistently present during VF: only 1 of 17 VF episodes contained a compound rotor that lasted for the entire mapped interval of 4 s. However, shorter-lived rotors were common; 12.2 (SD 3.3) compound rotors with lifetime >200 ms were visible on the epicardium at any given instant. We conclude that epicardial mother rotors do not drive VF in this experimental model; if mother rotors do exist, they are intramural or septal. This paucity of persistent rotors suggests that individual rotors will eventually terminate by themselves and therefore that the continual formation of new rotors is critical for VF maintenance.
在心室颤动（VF）期间，电激活波破碎，心脏无法同步收缩。有人提出，VF波源自稳定的周期性源（通常称为“母转子”）。本研究的目的是确定在大小与人心脏相当的心脏的心外膜表面是否始终存在稳定的转子。使用新的光学映射技术，我们对六个离体猪心脏几乎整个心室表面的VF进行了成像。使用新开发的模式分析算法，我们识别并跟踪了VF波前和相位奇点（PS；折返波前的枢轴点）。我们引入了复合转子的概念，其中转子的中心PS可以变化，并描述了一种自动识别此类模式的算法。这可防止转子寿命因PS附近的波前破碎和碰撞事件而被不适当地缩短。我们发现，在VF期间，稳定的心外膜转子并非始终存在：17次VF发作中只有1次包含一个持续整个4秒映射间隔的复合转子。然而，寿命较短的转子很常见；在任何给定时刻，心外膜上可见12.2（标准差3.3）个寿命>200毫秒的复合转子。我们得出结论，在这个实验模型中，心外膜母转子不会驱动VF；如果母转子确实存在，它们位于心肌内或间隔中。这种持续转子的稀缺表明单个转子最终会自行终止，因此新转子的持续形成对于VF的维持至关重要。
