Cellular mechanisms underlying the primary circadian pacemaker in mammals were investigated by isolating rat suprachiasmatic nuclei in brain slices and maintaining them in vitro for up to 3 days. The circadian rhythm of neuronal firing rate was used to assess the phase of the pacemaker. This rhythm was rapidly reset by bath application of cAMP analogs. Moreover, the pacemaker demonstrated circa...

THE RELATIONSHIP among cardiac pacemakers is characterized by the fact that usually one pacemaker is dominant and all the others are subsidiary. The sinoatrial node acts as the dominant pacemaker and all other pacemaker tissues are discharged by a conducted impulse before their diastolic depolarization can attain threshold. These pacemakers are called subsidiary to emphasize the fact that under...

THE RELATIONSHIP among cardiac pacemakers is characterized by the fact that usually one pacemaker is dominant and all the others are subsidiary. The sinoatrial node acts as the dominant pacemaker and all other pacemaker tissues are discharged by a conducted impulse before their diastolic depolarization can attain threshold. These pacemakers are called subsidiary to emphasize the fact that under...

The spontaneous activity of pacemaker cells in the sino-atrial node (SAN) controls the heart rhythm and rate under physiological conditions. Pacemaker activity in SAN cells is due to the presence of the diastolic depolarization, a slow depolarization phase that drives the membrane voltage from the end of an action potential to the threshold of a new action potential. SAN cells express a wide ar...

Health technology The study compared two treatment strategies for patients with chronic heart failure (CHF). The strategies compared were the conventional strategy and the pacemaker-carvedilol strategy. In the conventional strategy, patients were treated with angiotensin-converting enzyme inhibitors, diuretics and digoxin. In the pacemaker-carvedilol strategy, patients received conventional tre...

The use of cardiac pacemakers is increasing worldwide. Infective endocarditis from a pacemaker lead is a rare, but one of the most severe complications of pacemaker insertion. The diagnosis of pacemaker-related infective endocarditis is usually delayed due to unspecific clinical signs and symptoms at presentation compared to native valve infective endocarditis. Several factors can increase the ...

Each eye of Aplysia contains a population of electrically coupled pacemaker neurons whose synchronous activity can be recorded from the optic nerve as a compound action potential (CAP). The CAP frequency continues to show a circadian rhythm even when the eye is isolated from the animal and maintained in constant conditions, and thus it contains an autonomous circadian pacemaker, which may resid...

INTRODUCTION AND OBJECTIVES Our aim is to describe the analysis of the pacemaker implants and replacements reported to the Spanish Pacemaker Registry in 2010, with special reference to the selection of pacing modes. METHODS Data collection was based on the information provided by the European Pacemaker Patient Identification Card, which was processed using a specially designed computer applic...