الفهرس 
Right atrial appendageOnly 14 pages are availabe for public view
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Abstract
The programming of the AV delay intends to ensure optimal mechanical coordination between atrial and ventricular contractions, whether the atrium is sensed or paced. The optimal AV delay varies considerably among patients.
A programmed AV delay that is excessively long can be associated with an enhanced risk of pacemaker-mediated tachycardia, an enhanced risk of pacing during the vulnerable period of a ventricular extrasystole, an adverse hemodynamic effect with fusion of the E and A waves, premature closure of the mitral valve, and valvular regurgitation due to the reopening of the valves at the end of the ventricular diastole.
An inappropriately short programmed AV delay can be associated with a borderline atrial ejection volume with a loss of the active component, valvular regurgitation in early systole.
In patients with dual chamber pacemakers, ventricular activation achieved via synchronization between atria and ventricles is necessary to simulate normal cardiac physiology (mechanical AV synchrony). Achievement of this synchronization is possible by optimal setting of AV delay time. Previously it has been shown that the individual optimization of AV delay time has a positive effect on left ventricle (LV) performance. Furthermore, previous studies showed that patients optimized using aortic VTI experienced greater 3-month improvement in NYHA class and quality of life.
Although many methods have been used for the optimization of AV delay time, echocardiographic methods are still the most commonly used ones. However, there is no consensus as to which method should be the gold standard.