BACKGROUND The reentry circuit of atrioventricular nodal reentrant tachycardia (AVNRT) has not been fully demonstrated. We hypothesized that if an upper common pathway was present, the atrial electrogram could not be captured orthodromically during transient entrainment of AVNRT by rapid atrial pacing. Based on this hypothesis, the presence of an upper common pathway was investigated. METHODS...

1. Local inhibition in the deep layers of the superior colliculus plays a crucial role in sensorimotor integration. Using intracellular and extracellular recording techniques, we studied the organization of inhibitory circuits in the deep layers of the superior colliculus in anaesthetized rabbits. 2. We identified a new cell type in the deep superior colliculus that showed a characteristic burs...

Abstract Background Electrical pulse stimulations have been applied in brain for treating certain diseases such as movement disorders. High-frequency (HFS) of biphasic pulses used clinic stimulations, deep stimulation (DBS), to minimize the risk tissue damages caused by electrical stimulations. However, HFS sequences monophasic often animal experiments studying neuronal responses It is not clea...

The purpose of this study was to define specific types of resetting responses to programmed electrical stimulation during human ventricular tachycardia and to use computer simulations of reentry circuits to assess the possible mechanisms and pacing site location relative to the reentry circuit for each type of response. The effects of scanning single stimuli at 35 left ventricular endocardial s...

AIM Cardiac tissue deformation can modify tissue resistance, membrane capacitance and ion currents and hence cause arrhythmogenic slow conduction. Our aim was to investigate whether uniaxial strain causes different changes in conduction velocity (θ) when the principal strain axis is parallel vs perpendicular to impulse propagation. METHODS Cardiomyocyte strands were cultured on stretchable cu...

Background. We report that rapid atrial pacing interrupts atrial flutter when the orthodromic wave front from the pacing impulse is blocked in an area of slow conduction in the reentry circuit. To characterize the area of slow conduction during atrial flutter and rapid pacing, we studied 11 episodes of induced atrial flutter, mean cycle length 157+±20 msec, in eight dogs with sterile pericardit...

The first study, described in the companion article, reports that acute exposure of rat hippocampal slices to either hyperbaric oxygen (HBO: 2.84 and 4.54 atmospheres absolute, ATA) or normobaric reoxygenation (NBOreox; i.e., normobaric hyperoxia: 0.6 or 0.0→0.95 ATA) stimulates synchronous orthodromic activity in CA1 neurons, which includes activation of O2-induced potentiation (OxIP) and, in ...

BACKGROUND Recently, we used a custom designed "jacket" electrode with 127 bipolar electrodes in a flexible nylon matrix to map the total atrial epicardial surface in the in situ canine heart. Atrial flutter in dogs with sterile pericarditis was shown to be due to a single wave front circulating around a combined functional/anatomic obstacle, with the arc of functional conduction block contiguo...

Although both transient entrainment and resetting with single extrastimuli have been demonstrated during sustained ventricular tachycardia related to previous myocardial infarction, the relation between these phenomena has not been defined. Because transient entrainment is only demonstrated when the mechanism of a tachycardia is reentry with an excitable gap, the resetting response to timed pre...