Optimal AV Delay in Cardiac Patients treated by Dual Chamber Pacing
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Authors: Miroslav Mestan and Jiri Kvasnicka (Department of Internal Medicine; Faculty of Medicine in Hradec Kralove; Charles University Prague; University Hospital; Sokolska , Hradec Kralove, Czech Republic)
Book Description: The hemodynamic effect of the atria on the net performance of the heart is called atrial contribution (AC). AC is either linked to ventricular filling or to the systolic function of the heart, i.e. to the systolic volume or cardiac output. Several noninvasive methods for the quantification of AC are described in literature but none of them are routinely used in cardiac pacing centres due to the time-consuming nature of the methods, the limited reproducibility of measured values and observer-dependency.
The aim of of this book is to present a study to develop a method for determining optimal AV delay in patients treated by dual chamber pacing using an index (ACSp) that quantifies atrial contribution to the systolic volume of the left ventricle. The new method is based on the quantitative analysis of a beat to beat decrease in the amplitude of the pulse oximetry signal (SpO2). The change in the amplitudes is induced by a sudden drop of the stimulus to the right atrium, while maintaining the rate of ventricular stimuli at a constant level. The obtained ACSp is given as a percentage of the pulse amplitude of SpO2. The method is independent of the observer, noninvasive and relatively fast. In a group of 47 patients, remarkable similarities between ACSp and another atrial contribution index estimated using the tracings of invasively registered aortal pressure were demonstrated.
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