Choi B R, Liu T, Salama G
University of Pittsburgh, School of Medicine, 3500 Terrace St, S314 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
Circ Res. 2001 Mar 16;88(5):E49-58. doi: 10.1161/01.res.88.5.e49.
The spatial and dynamic properties of ventricular fibrillation (VF) may be random or related to cellular electrical properties of the normal heart. Local activation intervals (AIs) in VF may depend on the local refractory period (RP), and sustained VF may require a steep action potential (AP) restitution curve. In guinea pig hearts, AP durations (APDs) and RPs on the epicardium are shorter at the apex and progressively longer toward the base, producing gradients of RPs that may influence the spatial organization of VF. In the present study, the influence of APDs on VF dynamics is investigated in perfused guinea pig hearts stained with a voltage-sensitive dye by comparing APD gradients to the dynamics of VF elicited by burst pacing. In VF, AIs had no clear periodicity, but average AIs were shorter at the apex (57.5+/-8.1 ms) than the base (76.1+/-1.5 ms, n=6, P<0.05) and had gradients similar to APD gradients (correlation coefficient 0.71+/-0.04). Analysis of local velocity vectors showed no preferential directions, and fast Fourier transform (FFT) power spectra were broad (10 to 24 Hz) with multiple peaks (n=6). However, the selective inhibition of delayed K(+) rectifying currents, I(Kr) (E4031; 0.5 micromol/L, n=3), shifted FFT spectra from complex to a lower dominant frequency (10 Hz) and altered repolarization but retained the correlation between mean AIs and RPs. Thus, VF dynamics are consistent with a multiple wave-make and wave-break mechanism, and the local RP influences VF dynamics by limiting the range of VF frequencies and AIs at each site. The full text of this article is available at http://www.circresaha.org.
室颤（VF）的空间和动态特性可能是随机的，也可能与正常心脏的细胞电特性相关。室颤中的局部激活间期（AI）可能取决于局部不应期（RP），持续性室颤可能需要陡峭的动作电位（AP）恢复曲线。在豚鼠心脏中，心外膜的动作电位时程（APD）和不应期在 apex 处较短，向基部逐渐变长，产生了可能影响室颤空间组织的不应期梯度。在本研究中，通过将 APD 梯度与爆发起搏诱发的室颤动态进行比较，研究了 APD 对灌注豚鼠心脏中室颤动态的影响。在室颤中，AI 没有明显的周期性，但 apex 处的平均 AI（57.5±8.1 毫秒）比基部（76.1±1.5 毫秒，n = 6，P < 0.05）短，并且具有与 APD 梯度相似的梯度（相关系数 0.71±0.04）。局部速度矢量分析显示没有优先方向，快速傅里叶变换（FFT）功率谱很宽（10 至 24 赫兹）且有多个峰值（n = 6）。然而，对延迟钾离子整流电流 I(Kr)（E4031；0.5 微摩尔/升，n = 3）的选择性抑制将 FFT 谱从复杂转变为较低的主导频率（10 赫兹），并改变了复极化，但保留了平均 AI 和 RP 之间的相关性。因此，室颤动态与多波形成和波破碎机制一致，局部 RP 通过限制每个部位的室颤频率和 AI 范围来影响室颤动态。本文全文可在 http://www.circresaha.org 获得。
