Clinical Trials for Cardiac Pacing in Bradycardia

New concepts in physiologic cardiac pacing

Physiologic pacing is an evolving term used to describe different concepts and technologic developments in implantable devices (including pacemakers and defibrillators) over the past several decades. Currently much of the discussion about optimal physiologic pacing involves fairly recently appreciated deleterious effects of traditional right ventricular pacing. Technologic solutions to the goal of avoiding unnecessary ventricular pacing appear to be available and successful. Although much work is being done to find more physiologic ways to pace the ventricles when necessary, the solutions for this goal are less clear.

Novedades en estimulación cardiaca 2006

This article summarizes progress in cardiac pacing that has taken place in the last year, such as the incorporation of navigation technology into programmers, systems for monitoring hemodynamic parameters, and new developments in patient follow-up, principally home monitoring and the use of treatment guidelines. In addition, the article covers recent findings in resynchronization therapy, paroxysmal atrial fibrillation, and the management of patients with pacemakers who need to undergo magnetic resonance imaging.

Alloxan-induced diabetes reduces sarcolemmal Na+-K+ pump function in rabbit ventricular myocytes

The effect of diabetes on sarcolemmal Na(+)-K(+) pump function is important for our understanding of heart disease associated with diabetes and design of its treatment. We induced diabetes characterized by hyperglycemia but no other major metabolic disturbances in rabbits. Ventricular myocytes isolated from diabetic rabbits and controls were voltage clamped and internally perfused with the whole cell patch-clamp technique. Electrogenic Na(+)-K(+) pump current (I(p), arising from the 3:2 Na(+)-to-K(+) exchange ratio) was identified as the shift in holding current induced by Na(+)-K(+) pump blockade with 100 micromol/l ouabain in most experiments. There was no effect of diabetes on I(p) recorded when myocytes were perfused with pipette solutions containing 80 mmol/l Na(+) to nearly saturate intracellular Na(+)-K(+) pump sites. However, diabetes was associated with a significant decrease in I(p) measured when pipette solutions contained 10 mmol/l Na(+). The decrease was independent of membrane voltage but dependent on the intracellular concentration of K(+). There was no effect of diabetes on the sensitivity of I(p) to extracellular K(+). Pump inhibition was abolished by restoration of euglycemia or by in vivo angiotensin II receptor blockade with losartan. We conclude that diabetes induces sarcolemmal Na(+)-K(+) pump inhibition that can be reversed with pharmacological intervention.