A. Electrophysiological basis of arrhythmias B. Abnormal generation of impulse (1) Augmented automaticity Augmented automaticity in the myocardial cells other than the sinoatrial node cells will produce arrhythmias Maximal diastolic potential(MDP)in phase 4: ischemia, digitalis, sympathetic excitation imbalance of electrolytes Fast spontaneous depolarization in phase 4: fast response cells->slow response cells
◼ 3. Abnormal generation of impulse ◼ (1) Augmented automaticity ◼ Augmented automaticity in the myocardial cells other than the sinoatrial node cells will produce arrhythmias ◼ Maximal diastolic potential (MDP) in phase 4: ischemia, digitalis, sympathetic excitation, imbalance of electrolytes ◼ Fast spontaneous depolarization in phase 4：fast response cells → slow response cells A. Electrophysiological basis of arrhythmias
20 间电位 a. increased phase 4 slope Slow response 100毫秒 cel s 20 电位-2 0 B 上國位工 d b decreased thresold levels
a. increased phase 4 slope b. decreased thresold levels Slow response cells
A Electrophysiological basis of arrhythmias (2)Afterdepolarization and triggered activity early afterdepolarization (EAD): phases 2 3i longer Q-Tinterval (torsades de pointes); Ca2+ inward flow increases induced by drugs, plasma K+v delayed afterdepolarization (DAD) phase 4; Ca2+ inward flow leads to transient nat inward flow induced by digitalis intoxication, plasma Ca2+t, K+t
◼ (2) Afterdepolarization and triggered activity ◼ early afterdepolarization (EAD)： ◼ phases 2, 3; ◼ longer Q-T interval (Torsades de Pointes); ◼ Ca2+ inward flow increases ◼ induced by drugs, plasma K+ ◼ delayed afterdepolarization (DAD)： ◼ phase 4; ◼ Ca2+ inward flow leads to transient Na+ inward flow ◼ induced by digitalis intoxication, plasma Ca2+, K+ A. Electrophysiological basis of arrhythmias
Triggered beat A DAD Triggered beat B EAD A delayed afterdepolarization DAD) B early afterdepolarization (EAD)
A. delayed afterdepolarization (DAD) B. early afterdepolarization (EAD) Triggered beat Triggered beat
A. Electrophysiological basis of arrhythmias 4. Abnormal conduction of impulse (1) Simple conduction block slow and small depolarization in phase O, reduced MDP level in phase 4 MDP in ischemia, inflammation metabolic disorders Usually occurred in atrioventricular regions
◼ 4. Abnormal conduction of impulse ◼ (1) Simple conduction block ◼ slow and small depolarization in phase 0, reduced MDP level in phase 4 ◼ MDP in ischemia, inflammation, metabolic disorders； ◼ Usually occurred in atrioventricular regions A. Electrophysiological basis of arrhythmias