purpose: low back pain is one of the most common musculoskeletal disorders, and lifting is one of its risk factors. the activities of lumbar muscles as the main muscles involved in lifting are important with regard to identification of the allowable limits and the injury mechanisms as well as the motor control aspects. this study aimed to investigate the effects of the lifting speed on the lumb...

• Small-circuit reentry (microreentry) in which extremely slow conduction in a focal area sustains the reentry also presents with centrifugal activation. Unlike automaticity, however, the local bipolar electrograms at the site of the apparent focal source are fragmented and abnormal with microreentry. • When mapping 1 chamber, say the right atrium, but a macroreentry circuit is located within t...

background: complete atrioventricular block (av block) is a serious complication of slow pathway ablation therapy in the treatment of atrioventricular nodal re-entrant tachycardia (avnrt).   the present study was aimed at determining whether the electroanatomical pace mapping of koch’s triangle could significantly improve the safety, efficiency, and efficacy of selective slow pathway ablation i...

BACKGROUND Blockade of inward-rectifier K+ channels by chloroquine terminates reentry in cholinergic atrial fibrillation (AF). However, it is unknown whether inward-rectifier K+ channels and reentry are also important in maintaining stretch-induced AF (SAF). We surmised that reentry underlies SAF, and that abolishing reentry with chloroquine terminates SAF more effectively than traditional Na+-...

OBJECTIVES The purpose of this study was to determine the efficacy and risks of radiofrequency ablation of various forms of supraventricular tachycardia after Mustard and Senning operations for d-transposition of the great arteries. BACKGROUND In this patient group, the reported success rate of catheter ablation of intraatrial reentry tachycardia is about 70% with a negligible complication ra...

Multiple electrode mapping of the ventricles during complex tachyarrhythmias has revealed focal subendocardial activation whose mechanism remains unexplained. We hypothesized that reentry involving the Purkinje-muscle junctions (PMJs) may be a mechanism for such focal excitations. We have constructed an anatomically appropriate computerized 3-dimensional model of the mammalian ventricles that i...

This communication reports a numerical simulation of reentry induction by successive stimulation (S1-S2) that does not require an S1 gradient of refractoriness. The S1 action potential is uniform in space, so before the S2 stimulus there is no refractory gradient. Nevertheless, a unipolar S2 stimulus initiates quatrefoil reentry. The result supports the growing realization that virtual electrod...

A computer model of a ring-shaped, one-dimensional cardiac fiber was used for examination of responses of propagation to premature stimuli applied under different degrees of both cell-to-cell coupling and membrane excitability. Results demonstrated the importance of cellular uncoupling in the genesis of unidirectional block and reentry. Propagation of excitation itself created a certain degree ...

High-energy defibrillation shock is the only therapy for ventricular tachyarrhythmias. However, because of adverse side effects, lowering defibrillation energy is desirable. We investigated mechanisms of unpinning, destabilization, and termination of ventricular tachycardia (VT) by low-energy shocks in isolated rabbit right ventricular preparations (n = 22). Stable VT was initiated with burst p...