2. Affecting factor small 5-10min: arrhythmia (1)ischemic (animals 20-30min: ventricular tremor time big 20-40min: reversible injury animals [40-60min: irreversible injury diversity between small and big animal2．Affecting factor small 5-10min: arrhythmia ⑴ ischemic animals 20-30min: ventricular time tremor big 20-40min: reversible injury animals 40-60min: irreversible injury diversity between small and big animal