Nearing Bruce D, Verrier Richard L
Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
J Appl Physiol (1985). 2003 Dec;95(6):2265-72. doi: 10.1152/japplphysiol.00623.2003. Epub 2003 Aug 1.
Oscillations in T-wave morphology, particularly T-wave alternans (TWA), have been fundamentally linked to increased susceptibility to ventricular fibrillation (VF). We investigated whether the escalation in complexity of T-wave oscillations before VF is attributable to increased spatial heterogeneity of repolarization. Peak interlead T-wave heterogeneity (TWH) was measured by second central moment analysis of T-wave morphology in epicardial electrograms in dogs during left anterior descending coronary artery occlusion. TWH differentiated cases in which myocardial ischemia provoked VF from those without VF (563 +/- 56 vs. 139 +/- 36 microV, P < 0.01). In the former group, progressive, significant increases in TWH above preocclusion baseline (70 +/- 8 microV) began at 2.25 min after the start of occlusion and were associated successively with TWA (at 155 +/- 19 microV), T-wave multupling (at 386 +/- 100 microV), complex oscillatory T-wave forms (at 560 +/- 76 microV), discordant TWA (at 572 +/- 98 microV), and VF at 4.36 +/- 0.14 min. TWH in precordial ECGs in 12 pigs during angioplasty-balloon-induced myocardial ischemia also discriminated animals that experienced VF (from 90 +/- 14 at baseline to 382 +/- 39 microV, P < 0.05) from those without VF (from 96 +/- 17 at baseline to 199 +/- 61 microV, NS). Ischemia-induced changes in ST segment and T-wave amplitude did not predict VF. Heightened spatial heterogeneity of repolarization, as assessed by second central moment analysis of TWH, underlies TWA and increased risk for ischemia-induced VF. Monitoring spatial TWH from precordial leads could prove useful in stratifying risk for life-threatening arrhythmias.
T波形态的振荡，尤其是T波交替（TWA），与心室颤动（VF）易感性增加有着根本联系。我们研究了VF发作前T波振荡复杂性的增加是否归因于复极化空间异质性的增加。通过对犬左前降支冠状动脉闭塞期间心外膜电图T波形态进行二阶中心矩分析来测量导联间T波异质性（TWH）峰值。TWH能够区分心肌缺血诱发VF的病例与未发生VF的病例（563±56微伏对139±36微伏，P<0.01）。在前一组中，闭塞开始后2.25分钟时，TWH开始高于闭塞前基线（70±8微伏）并逐渐显著增加，依次与TWA（155±19微伏时）、T波多重化（386±100微伏时）、复杂振荡T波形态（560±76微伏时）、不一致TWA（572±98微伏时）以及4.36±0.14分钟时的VF相关。在12只猪血管成形术球囊诱导心肌缺血期间，胸前心电图的TWH也能区分发生VF的动物（从基线时的90±14微伏增至382±39微伏，P<0.05）与未发生VF的动物（从基线时的96±17微伏增至199±61微伏，无显著差异）。缺血引起的ST段和T波振幅变化无法预测VF。通过TWH的二阶中心矩分析评估，复极化空间异质性增加是TWA以及缺血诱发VF风险增加的基础。监测胸前导联空间TWH可能有助于对危及生命的心律失常风险进行分层。
