Ventricular arrhythmias, consisting of single ectopic beats (sEB), multiple EB (mEB), and Torsades de Pointes (TdP, defined as >5 beats with QRS vector twisting around isoelectric line) can be induced in the anesthetized chronic AV-block (CAVB) dog by dofetilide (I_Kr-blocker). The interplay between temporal dispersion of repolarization, quantified as short-term variability (STV), and spatial dispersion of repolarization (SDR) in the initiation and perpetuation of these arrhythmias remains unclear. Five inducible (>3 TdPs/10') CAVB dogs were observed for 10' from the start of dofetilide infusion (0.025mg/kg, 5'). An intracardiac decapolar electrogram (EGM) catheter and 30 intramural cardiac needles in the left ventricle (LV) were introduced. STV_ARI was derived from 31 consecutive activation recovery intervals (ARI) on the intracardiac EGM, using the formula: . The mean SDR_3D in the LV was determined as the three-dimensional repolarization time differences between the intramural cardiac needles. Moments of measurement included baseline (BL) and after dofetilide infusion prior to first 1) sEB (occurrence at 100±35"), 2) mEB (224±96"), and 3) non self-terminating TdP (454±298"). STV_ARI increased from 2.15±0.32ms at BL to 3.73±0.99ms* prior to the first sEB and remained increased without further significant progression to mEB (4.41±0.45ms*) and TdP (5.07±0.84ms*) (*p<0.05 compared to BL). SDR_3D did not change from 31±11ms at BL to 43±13ms prior to sEB, but increased significantly prior to mEB (68±7ms*) and to TdP (86±9ms*⁺) (⁺p<0.05 compared to sEB). An increase in STV contributes to the initiation of sEB whereas an increase in SDR is important for the perpetuation of non self-terminating TdPs.

中文翻译：

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慢性房室传导阻滞犬尖端扭转型室性心动过速的发生和持续过程中复极的时间和空间分散之间的相互作用

在麻醉的慢性房室传导阻滞 (CAVB) 中可诱发室性心律失常，包括单次异位搏动 (sEB)、多次 EB (mEB) 和尖端扭转型室性心动过速 (TdP，定义为 QRS 向量绕等电位线扭曲的 >5 次搏动) ) 多非利特 (I _Kr受体阻滞剂) 的狗。在这些心律失常的发生和持续过程中，复极时间离散度（量化为短期变异性（STV））和复极空间离散度（SDR）之间的相互作用尚不清楚。从多非利特 (0.025mg/kg, 5') 开始输注 10'，观察了五只诱导型 (>3 TdPs/10') CAVB 犬。在左心室 (LV) 中引入了心内十极电图 (EGM) 导管和 30 根壁内心脏针。STV _ARI来自心内 EGM 的 31 个连续激活恢复间隔 (ARI)，使用公式：LV 中的平均 SDR _3D被确定为壁内心脏针之间的三维复极时间差。测量时刻包括基线 (BL) 和第一次输注多非利特后 1) sEB（发生在 100±35"），2）mEB (224±96")，和 3）非自终止 TdP (454±298") ). STV _ARI从 BL 的 2.15±0.32ms 增加到第一个 sEB 之前的 3.73±0.99ms* 并且保持增加而没有进一步显着进展到 meB (4.41±0.45ms*) 和 TdP (5.07±0.84ms*) (*与 BL 相比，p<0.05。SDR _3D没有从 BL 的 31±11ms 变为 sEB 之前的 43±13ms，但在 meB (68±7ms*) 和 TdP (86±9ms* ⁺ )之前显着增加（与 sEB 相比⁺ p<0.05）。STV 的增加有助于 sEB 的启动，而 SDR 的增加对于非自我终止 TdP 的延续很重要。