The objective was to test if changes in autonomic tone still influenced the RT-RR relationship when full RT adaptation is completed, when heart rate is controlled, and when beat-to-beat variability is abolished by atrial pacing. Eight dogs (8-11 kg) were chronically instrumented with atrial pacing electrodes. Digital ECG (1,000 Hz, 12 bits) were recorded from healthy conscious dogs during spont...

BACKGROUND AND PURPOSE Visit-to-visit and day-to-day variability in systolic blood pressure (SBP) are associated with an increased risk of stroke, more strongly than variability on 24-hour ambulatory BP monitoring, but underlying physiological mechanisms are unclear. We related potentially relevant physiological characteristics to beat-to-beat, ambulatory, and day-to-day BP variability to ident...

4. Noise cancellation. A classical problem in statistical signal processing involves estimating a weak signal (e.g., the heart beat of a fetus) in the presence of a strong interference (the heart beat of its mother) by making two observations; one with the weak signal present and one without (by placing one microphone on the mother’s belly and another close to her heart). The observations can t...

The adult abdominal heart of Drosophila melanogaster receives extensive innervation from glutamatergic neurons at specific cardiac regions during metamorphosis. Here, we show that the neurons form presynaptic specializations, as indicated by the localization of synaptotagmin and active zone markers, adjacent to postsynaptic sites that have aggregates of glutamate IIA receptors. To determine the...

Abstract Background QT interval varies with the heart rate (HR), so a correction in calculation is needed (QTc). Atrial fibrillation (AF) associated elevated (HR) and beat-to-beat variation length of RR making challenging. Aim to evaluate which formula better correlates QTc sinus rhythm after electrical cardioversion (ECV). Methods During 3-month period, we considered patients who underwent 12-...

Heart cells growing as monolayer cells in tissue culture have the ability to beat (1) . After several day in culture these same cells cease functioning and lose the morphology characteristic of beating cells . This process by which heart cells lose their ability to beat in culture has been described as dedifferentiation (2) . While studying the effect of steroids on beating, McCarl et al . (3) ...

Background Myocardial perfusion cardiovascular magnetic resonance (CMR) with vasodilator stress has high diagnostic accuracy for detecting coronary artery disease (CAD). Current CMR perfusion pulse sequences use largely fixed acquisition parameters designed to acquire at least three slices every heart beat, optimized for the heart rates that typically occur during pharmacological stress. In pat...

In this paper we investigate the influence of vagal blockage on heart rate variability complexity measures. Nine conscious rats are injected with methyl-scopolamine brobide (50 μg/kg s.c.). We analyze 10 minute segments of beat-to-beat intervals before and after injection by standard time and frequency domain methods, compression entropy, sample entropy, Poincaré plot, detrended fluctuation ana...