It has become widely accepted that the most dangerous cardiac arrhythmias are due to reentrant waves, i.e., electrical wave(s) that recirculate repeatedly throughout the tissue at a higher frequency than the waves produced by the heart's natural pacemaker (sinoatrial node). However, the complicated structure of cardiac tissue, as well as the complex ionic currents in the cell, have made it extr...

Conventional teaching suggests that the initiation of arrhythmias requires an initiating “trigger” and a suitable “substrate.” Moreover, the hallmark of electro-anatomic substrates for reentrant arrhythmias is spatially heterogeneous structural or electrophysiological properties. The fundamental requirement of heterogeneous refractory properties is not a new concept and was recognized by the ea...

The role of dynamic instabilities in the initiation of reentry in diseased (remodeled) hearts remains poorly explored. Using computer simulations, we studied the effects of altered Na(+) channel and cell coupling properties on the vulnerable window (VW) for reentry in simulated two-dimensional cardiac tissue with and without dynamic instabilities. We related the VW for reentry to effects on con...

We have studied the effects of quenched random disorder created by dispersed aerosil nanoparticle gels on the nematic to smectic- A (N- SmA ) and smectic- A to reentrant nematic ( SmA -RN) phase transitions of thermotropic liquid-crystal mixtures of hexyloxycyanobiphenyl (6OCB) and octyloxycyanobiphenyl (8OCB). These effects are probed using high-resolution synchrotron x-ray diffraction techniq...

Studies have shown that in patients with paroxysmal supraventricular tachycardia (SVT), spontaneous or stimulated atrial premature depolarizations (APD) falling within a specific portion of the relative refractory period of the atrioventricular (A-V) conduction system initiate SVT. The present study was designed to determine whether the A-V nodal conduction delay these APDs exhibit, or their co...

AIMS In patients without pre-excitation, the differential diagnosis of paroxysmal atrioventricular (AV) reciprocating tachycardias consists mainly of atrioventricular nodal re-entrant tachycardias (AVNRTs) and AV reciprocating tachycardias (AVRTs) through a concealed bypass. Our purpose was to validate the diagnostic accuracy of a predictive logistic model using classical electrocardiographic (...

BACKGROUND We report the first successful slow pathway ablation using a novel catheter-based cryothermal technology for the elimination of atrioventricular nodal reentrant tachycardia (AVNRT). METHODS AND RESULTS Eighteen patients with typical AVNRT underwent cryoablation. Reversible loss of slow pathway (SP) conduction during cryothermy (ice mapping) was demonstrated in 11 of 12 patients. Be...

BACKGROUND Immunohistochemistry studies suggest that the anatomic substrate of the slow pathway in atrioventricular nodal reentrant tachycardia (AVNRT) is the left inferior nodal extension. We hypothesized that slow pathway ablation from the left septum is an effective alternative to right-sided ablation. METHODS AND RESULTS We analyzed our databases of AVNRT in search of cases that had used ...

Reentrant ventricular tachycardia (VT) is the most common sustained arrhythmia leading to ventricular fibrillation (VF). However, despite more than a century of research, the mechanism(s) of the conversion from reentrant VT to VF have not been elucidated. Based on their different electrocardiographic appearance, reentrant VT and VF have traditionally been thought of as resulting from two widely...

BACKGROUND Slow-pathway ablation or modification eliminates typical atrioventricular nodal re-entrant tachycardia (AVNRT) but with a 1% risk of AV block. We report our experience from a series of consecutive patients with typical AVNRT who were ablated in our unit. METHODS Consecutive patients (n=227), aged 22 to 56 years, 172 women, with slow-fast AVNRT underwent slow-pathway ablation. Mappi...