Cardiac memory refers to an altered T-wave morphology induced by ventricular pacing or arrhythmias that persist for variable intervals after resumption of sinus rhythm. We induced long-term cardiac memory (LTM) in conscious dogs by pacing the ventricles at 120 bpm for 3 weeks. ECGs were recorded daily for 1 hour, during which time pacing was discontinued. At terminal study, the heart was removed and the electrophysiology of left ventricular epicardial myocytes was investigated. Control (C) and LTM ECG did not differ, except for T-wave amplitude, which decreased from 0.12+/-0.18 to -0.34+/-0.21 mV (+/-SEM, P<0.05), and T-wave vector, which shifted from -37+/-12 degrees to -143+/-4 degrees (P<0.05). Epicardial action potentials revealed loss of the notch and lengthening of duration at 20 days (both P<0.05). Calcium-insensitive transient outward current (Ito) was investigated by whole-cell patch clamp. No difference in capacitance was seen in C and LTM myocytes. Ito activated on membrane depolarization to -25+/-1 mV in C and -7+/-1 mV (P<0.05) in LTM myocytes, indicating a positive voltage shift of activation. Ito density was reduced in LTM myocytes, and a decreased mRNA level for Kv4.3 was observed. Recovery of Ito from inactivat...Continue Reading
Electrocardiographic characteristics and main causes of pseudoprimary T wave changes. Significance of concordant and discordant T waves in the human and other animal species
Developmental analysis reveals mismatches in the expression of K+ channel alpha subunits and voltage-gated K+ channel currents in rat ventricular myocytes
Regulation of cardiac shal-related potassium channel Kv 4.3 by serum- and glucocorticoid-inducible kinase isoforms in Xenopus oocytes
Reversal of primary and pseudo-primary T wave abnormalities by ventricular pacing. A novel manifestation of cardiac memory
Changes in left ventricular repolarization and ion channel currents following a transient rate increase superimposed on bradycardia in anesthetized dogs
Properties and ionic mechanisms of action potential adaptation, restitution, and accommodation in canine epicardium
Repolarization changes underlying long-term cardiac memory due to right ventricular pacing: noninvasive mapping with electrocardiographic imaging
Electrophysiological consequences of dyssynchronous heart failure and its restoration by resynchronization therapy
Establishment of a canine model of cardiac memory using endocardial pacing via internal jugular vein
Electrical remodeling of the ventricular myocardium in myocarditis: studies of rat experimental autoimmune myocarditis
Comparison of vectorcardiographic and 12-lead electrocardiographic detections of abnormalities in repolarization properties due to preexcitation in patients with Wolff-Parkinson-White syndrome: proposal of a novel concept of a "remodeling gradient"
Cumulative inactivation of the outward potassium current: a likely mechanism underlying electrical memory in human atrial myocytes
The molecular physiology of the cardiac transient outward potassium current (I(to)) in normal and diseased myocardium
Effects of candesartan on electrical remodeling in the hearts of inherited dilated cardiomyopathy model mice
Vectorcardiographic determinants of cardiac memory during normal ventricular activation and continuous ventricular pacing
Deleting the accessory subunit KChIP2 results in loss of I(to,f) and increased I(K,slow) that maintains normal action potential configuration
Inhomogeneity in the response to mechanical stimulation: cardiac muscle function and gene expression
Right ventricular pacing-induced electrophysiological remodeling in the human heart and its relationship to cardiac memory
Right ventricular outflow tract pacing: relation of high to low synchronous ventricular activation with cardiac memory
Pacing-induced electrophysiological remodeling in hypertrophic obstructive cardiomyopathy--observations on cardiac memory
Correlation of electrotonic monophasic action potential shortening with short-term memory in human atrium
Irregular ventricular activation results in QT prolongation and increased QT dispersion: a new insight into the mechanism of AF-induced ventricular arrhythmogenesis
Long-term changes in sequence of atrial activation and refractory periods: no evidence for "atrial memory"
Electrical remodeling reflected by QRS and T vector changes following cardiac resynchronization therapy is related to survival in heart failure patients with left bundle branch block
Discover the latest cardiology research in this collection of the top cardiology journals.
Atrial fibrillation is a common arrhythmia that is associated with substantial morbidity and mortality, particularly due to stroke and thromboembolism. Here is the latest research.
Arrhythmias are abnormalities in heart rhythms, which can be either too fast or too slow. They can result from abnormalities of the initiation of an impulse or impulse conduction or a combination of both. Here is the latest research on arrhythmias.
Cardiac electrophysiology is the study of electrical activities of the heart and includes the assessment, diagnosis, and treatment of cardiac events. Find the latest research on cardiac electrophysiology here.