afterdepolarization


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afterdepolarization

 [af″ter-de-po″lah-rĭ-za´shun]
an oscillation in membrane potential that is dependent upon a preceding action potential for its initiation, and which upon reaching threshold potential can induce arrhythmias that are said to be “triggered.” Early afterdepolarizations occur during phases 2 and 3 of repolarization; delayed afterdepolarizations follow full repolarization.
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Effects of Shenmai injection on afterdepolarization and triggered activities in left ventricular papillary muscle in rat cardiac: Hypertrophy.
Weiss, "Multiscale Determinants of Delayed Afterdepolarization Amplitude in Cardiac Tissue," Biophysical Journal, vol.
Another research aimed to investigate the combined role of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and [beta]-adrenergic signaling pathway in regulating early afterdepolarization. Early afterdepolarization (EAD) has tremendous relevance for the onset of arrhythmogenesis.
This increases the risk of early afterdepolarization, which, in turn, can cause polymorphic ventricular tachycardia.
[sup][58],[60] Due to a marked difference in AP duration and the property of the delayed dome similar to early afterdepolarization, [sup][61] the dome may produce a new AP in the areas where complete loss of epicardial AP is present, leading to formation of short-coupled ectopic beats, which can be capable of originating polymorphic VT or VF.
reported that perfusion of [Ca.sup.2+] and [Ca.sup.2+] complexes in animal hearts could not induce similar myocardial injury to MIRI, especially early afterdepolarization (EAD) [42].
Abbreviations AP: Action potential APD: Action potential duration CM: Cardiomyocyte EB: Embryoid body EAD: Early afterdepolarization ECG: Electrocardiogram hESC: Human embryonic stem cell hiPSC: Human-induced pluripotent stem cell ICD: Implantable cardioverter defibrillator miPSC: Murine-induced pluripotent stem cells LQT(S): Long QT (syndrome) QT-Interval: Time between start and end of cardiac ventricular electrical depolarization.
Increased vagal tone is associated with a shortened atrial effective refractory period and increased dispersion [3,17], whereas sympathetic stimulation may lead to afterdepolarization and triggered firing [18], which facilitate the initiation and maintenance of
Ventricular hypertrophy amplifies transmural repolarization dispersion and induces early afterdepolarization. Am J Physiol Heart Circ Physiol 2001; 281: H 1968-75.
Ni ions have been reported to induce vasoconstriction and early afterdepolarization in isolated rat heart and canine coronary artery by enhancing [Ca.sup.2+] influx into vascular smooth muscle cells (Golovko et al.
Delayed afterdepolarization reaching a critical threshold can trigger clinical arrhythmias, including ventricular extrasystoles, bidirectional ventricular tachycardia, and VF [17].
On the contrary, other studies reported that [beta]-adrenergic agonists activate protein kinase A (PKA), which phosphorylates [I.sub.CaL], RyR, PLB, SERCA, and [I.sub.Ks], resulting in delayed afterdepolarization (DADs) [18].