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BACKGROUND Cardiac memory (CM) refers to T-wave changes induced by ventricular pacing or arrhythmia that accumulate in magnitude and duration with repeated episodes of abnormal activation. We report herein the kinetics of long-term CM and its association with the ventricular action potential. METHODS AND RESULTS Dogs were paced from the ventricles at(More)
OBJECTIVE Our goal was to study rate adaptation of atrial action potentials in non-steady and steady states to further our understanding of mechanisms determining inducibility and stability of atrial fibrillation. METHODS We used standard microelectrode techniques to examine the characteristics of steady-state action potentials paced at regular cycle(More)
BACKGROUND 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. METHODS AND RESULTS 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(More)
BACKGROUND Anisotropic conduction properties may provide a substrate for reentrant arrhythmias. We investigated the age-dependent changes of structural and functional anisotropy in isolated right atria from infant (1 to 2 months), young (6 to 12 months), and old (6 to 10 years) dogs. METHODS AND RESULTS The histology of the mapped atrial tissues (a small(More)
OBJECTIVE To determine whether I(Na) and I(CaL) are altered in function/density in right atrial (RA) cells from dogs with chronic atrial fibrillation (cAF dogs, episodes lasting at least 6 days) and whether the changes that occur differ from those in dogs with nonsustained or brief episodes of fibrillation (nAF dogs). METHODS Using whole cell voltage(More)
OBJECTIVE We tested the hypothesis that delayed afterdepolarization (DAD)-associated rhythms in German shepherd dogs with reduced anteroseptal left ventricular (LV) sympathetic innervation derive from abnormal beta-adrenergic receptor effector coupling. METHODS AND RESULTS In anteroseptal LV midmyocardium of afflicted dogs, beta-receptor density was(More)
BACKGROUND Metabolic syndrome (MetS), which includes a cluster of risk factors, is being increasingly recognized as a new risk factor for cardiovascular disease. Heart rate turbulence (HRT) is a Holter-based non-invasive method for detecting cardiac autonomic imbalance and is an independent, powerful predictor of cardiac arrhythmias and sudden cardiac death(More)
The present study examined whether visually evoked fear of depth could reinforce a particular response of animals, i.e., to special maze learning. The maze was composed of four units of Y-shaped alley. In this maze, the visual pitfalls were set behind corners of the alley in place of a physical barrier. The experiments showed that eight of 13 male chicks(More)
The present study examined the heart-rate changes which occurred in the visual-depth situation of Japanese monkeys (Macaca fuscata). Four animals were tested over the first four weeks of age in the visual pitfall designed as a modification of the visual cliff. The infant monkeys showed heart-rate reduction in the depth condition. This reduction was observed(More)
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