BACKGROUND Conventional cardiac pacemakers are associated with several potential short- and long-term complications related to either the transvenous lead or subcutaneous pulse generator. We tested the safety and clinical performance of a novel, completely self-contained leadless cardiac pacemaker. METHODS AND RESULTS The primary safety end point was freedom from complications at 90 days. Sec...

The influences of ventricular pacing at a rate of 70 beats/min (bpm) on the systemic and coronary hemodynamics, myocardial metabolism, and cardiac work efficiency were evaluated in five patients with bradycardia. The results were compared to those obtained in six normal subjects at rest. In order to elucidate the effects of a relatively high rate of ventricular pacing, cardiovascular and metabo...

I(f), the "cardiac pacemaker current," is a nonselective cation channel activated on hyperpolarization in primary and secondary pacemaker regions of the mammalian heart. The cardiac pacing rate can be modulated by shifting the activation of I(f) to more positive (faster pacing) or more negative (slower pacing) voltages. We report for the first time the presence of this pacemaker current in vent...

Despite significant advances in battery longevity, lead performance, and programming features since the first implanted permanent pacemaker was developed, the basic design of cardiac pacemakers has remained relatively unchanged over the past 50 years. Because of inherent limitations in their design, conventional (transvenous) pacemakers are prone to multiple potential short- and long-term compl...

Chronic rapid ventricular pacing in the dog reportedly produces a useful preparation of low-output heart failure. However, little information is available regarding cardiac changes in this preparation. Accordingly, we evaluated the effects of both short-term (3 weeks) and prolonged (2 months) rapid ventricular pacing on cardiac hemodynamics, mass, and chamber size. The effects of short-term pac...

Bistability in periodically paced cardiac tissue is relevant to cardiac arrhythmias and its control. In the present paper, one-dimensional tissue of the phase I Luo-Rudy model is numerically investigated. The effects of various parameters of pacing signals on bistability width are studied. The following conclusions are obtained: (i) Pacing can be classified into two types: pulsatile and sinusoi...

STUDY OBJECTIVES Pacing-induced asynchrony may deteriorate left ventricular function; however, limited data exists in humans. The aim of our study was to compare left ventricular hemodynamics during short-term atrioventricular sequential pacing from the right ventricular apex and from the outflow tract of the right ventricle. DESIGN Three 5-min pacing intervals were applied in a random order,...

Cardiac pacing is the only treatment available for patients with Symptomatic bradyarrhythmias in absence of reversible causes. For about 50 Apical right ventricular has been used years.

BACKGROUND Cardiac resynchronization therapy has been shown to improve systolic function in patients with advanced chronic heart failure and electromechanical delay (QRS width > 120 ms). However, the effect of acute biventricular (BiV) pacing on perioperative haemodynamic changes is not well defined. In the present study, acute changes in regional left ventricular (LV) systolic function determi...

OBJECTIVES We sought to investigate whether patients with syndrome X have an abnormal perception of cardiac pain. BACKGROUND Previous studies have reported an increased sensitivity to potentially painful cardiac stimuli in patients with syndrome X. However, it is not clear whether this increase is due to an increased perception of pain or to an enhanced tendency to complain. METHODS We asse...