AIMS Surgical treatment for atrial fibrillation is now feasible in selective cases. The aim of this study was to assess the electrophysiological properties of patients undergoing atrial compartment operation for chronic atrial fibrillation. METHODS AND RESULTS Electrophysiological studies were performed in 20 mitral valve patients with atrial fibrillation who had been maintained in sinus rhyt...

Ca 2+ is a strategic intracellular second messenger regulating multifarious cardiac cellular processes. This Frontiers issue on Ca 2+ signaling and cardiac rhythm first focuses on the spontaneous membrane depolarization triggering action potential (AP) pacing by sino-atrial node (SAN) cells. These drive normal rhythmic atrial followed by ventricular depolarization initiating effective systolic ...

Sino-atrial conduction time (SACT) may be calculated from the difference between the length of the return cycle and the spontaneous cycle, using programmed premature atrial stimulation during spontaneous sinus rhythm. This approach to sinoatrial conduction assumes that sinus node automaticity is not changed by premature depolarization. In order to validate this assumption, we compared the lengt...

We investigate nonlinear instabilities in human heart rate variability. We focus on phenomena with characteristic, easily recognizable features which are well known in physics. In the past we were able to show two groups of evidence. The first was an ever expanding roster of such cases of heart rate variability pathology which exhibit type I intermittency. This phenomenon occurs in those dynami...

The negative chronotropic effects of eight Vaughan Williams Class I antiarrhythmic drugs were examined in guinea pig right atrial tissue preparations. decreased the spontaneous beating rate at concentrations overlapping with their therapeutic blood levels. Cibenzoline, aprindine, flecainide, and propafenone showed stronger effects; 10 µM each drug to about 75% initial values. Disopyramide, mexi...