Background—The pacemaker current If is present in atrial and ventricular myocytes. However, it remains controversial whether If overexpression in diseased states might play a role for arrhythmogenesis, because first If activation in whole-cell recordings hardly overlapped the diastolic voltage of working myocardium. Methods and Results—To obtain further insight into IHCN and If properties, we p...

A 25-year-old man with idopathic atrial flutter and high grade atrioventricular (AV) block is described. Postcardioversion, sino-atrial (SA) and AV nodal dysrhythmias occurred. Treadmill exercise during atrial flutter increased AV conduction to 2:1, and normalized SA and AV nodal function following cardioversion. A neurogenic basis for these arrhythmias is hypothesized.

The cardiac pacemaker is a sino-atrial (SA) nodal cell. The signal induced by this pacemaker is distributed over the heart surface by a specialised conduction system and is clinically recorded as the ECG. The SA nodal cells are highly resistant to cardiac failure and ischemia. Under calcium overload conditions, some dysrythmias of SA nodal cells occur easily. Morphological analysis under these ...

Impulse generation in supraventricular tissue is inhibited by adenosine and acetylcholine via the activation of A1 and M2 receptors coupled to inwardly rectifying GIRK/KIR3.1/3.4 channels, respectively. Unlike M2 receptors, bradycardia produced by A1 receptors activation predominates over negative inotropy. Such difference suggests that other ion currents may contribute to adenosine chronoselec...