Acute effects of zatebradine on cardiac conduction and repolarization

Heart rate dependence of aortic pulse wave velocity at different arterial pressures in rats

Arterial stiffness, as measured by aortic pulse wave velocity (PWV), is an independent marker of cardiovascular disease and events in both healthy and diseased populations. Although some cardiovascular risk factors, such as age and blood pressure, show a strong association with PWV, the association between heart rate (HR) and PWV is not firmly established. Furthermore, this association has not been investigated at different arterial blood pressures. To study effects of HR on aortic PWV at different mean arterial pressures (MAPs), adult (12 weeks; n=7), male, anesthetized Sprague-Dawley rats were randomly paced at HRs of between 300 and 450 bpm, at 50-bpm steps. At each pacing step, aortic PWV was measured across a physiological MAP range of 60 to 150 mmHg by infusing sodium nitroprusside and phenylephrine. When compared at the same MAP, increases in HR resulted in significant increases in PWV at all of the MAPs >80 mmHg (ANOVA, P<0.05), with the greatest significant change of 6.03±0.93% observed in the range 110 to 130 mmHg. The positive significant association between HR and PWV remained when PWV was adjusted for MAP (ANOVA, P<0.001). These results indicate that HR dependency of PWV is different at higher pressures than at lower pressures and that HR may be a confounding factor that should be taken into consideration when performing analysis based on PWV measurements.

Antiarrhythmic drugs: new agents and evolving concepts

Properties of several new antiarrhythmic drugs are summarised in this review article. Recent concepts concerning their safety and efficacy of antiarrhythmics are discussed. A brief perspective on possible future strategies for pharmacotherapy of arrhythmias is provided.