Optimization of the atrioventricular delay in sequential and biventricular pacing: physiological bases, critical review, and new purposes

Abstract

Atrioventricular (AV) delay optimization in sequential and biventricular (BiV) pacing, although widely recommended, is often poorly performed in clinical practice as an improper setting can reduce the success of the stimulation. Despite the several methods proposed, the AV delay is frequently programmed in an empirical way or left to a predefined value (usually the manufacturer's setting), without considering the different variables involved in this context, concerning the intra- and interindividual variability of the electromechanical events, the peculiarities of the several cardiopathies, the spontaneous interatrial and AV conduction, the pharmacological therapy, and the pacing mode. The manuscript illustrates the physiological bases of the optimization, describes why and how to programme the best AV delay at rest and during daily activities and discusses critically all methods proposed, divided into three groups: predefined formulas, iterative attempts, and automatic settings. The manuscript is not only a review because it tries to clarify this complex topic, stating the fundamental concept in BiV pacing; the optimal AV delay should be short enough to have always a pre-exitated stimulation and contemporary an optimal left ventricular filling. The paper suggests new purposes and new solutions for this goal, it shows the limits of the actual guidelines and the disappointing results obtained in several studies by automatic methods, goading to find new algorithms.

Association between frequent cardiac resynchronization therapy optimization and long-term clinical response: a post hoc analysis of the Clinical Evaluation on Advanced Resynchronization (CLEAR) pilot study

“…They often result in a time-consuming process, requiring high cost and labour intensity. 8–13 Consequently, CRT is often not optimized in clinical practice. 11 In an attempt to overcome these difficulties, device manufacturers are developing automated sensing methods and algorithms for assessing cardiac performance and adapting CRT delivery according to patients' changing needs, allowing a more rapid, simplified, and automated or semi-automated approach to CRT optimization.…”

Clinical benefit of atrio-ventricular delay optimization in patients with a dual-chamber pacemaker: a pilot study. The CBRAVO trial (NCT01998256)

“…Though this timing was arbitrary, the aim was to examine a sustained short-term effect of AV optimization on exercise capacity, in contrast to the established acute haemodynamic effects 4,5 . AV optimization in our study was performed at rest, using the validated iterative mitral inflow VTI method 6 . We used this specific method because of our experience with this technique and because of its clinical feasibility, though aortic VTI and Ritter's method for DDD pacemaker optimization are likewise validated.…”

“…Several validated methods for AV optimization exist 6 . However, data on the effects of this intervention on short-and long-term clinical end points as exercise capacity, morbidity and mortality, are sparse.…”

“…Echo-guided AV optimization was performed using the iterative mitral inflow VTI (velocity time integral) method 6 . In brief, this method consists in programming a long AV delay and reducing it in 20 ms steps until the A-wave truncates.…”

Hemodynamic Sensor in Cardiac Implantable Electric Devices: The Endocardial Accelaration Technology

“…Over time, a progressive improvement of the available diagnostic and therapeutic algorithms has been observed, mainly related to the detection of cardiac arrhythmias, management of pacing/sensing thresholds, reduction of unnecessary ventricular pacing, prevention of atrial tachyarrhythmias recurrence, development of rate responsive pacing and rate adaptive atrioventricular (AV) delay functions, allowing a better management of patients. A reliable continuous hemodynamic information could improve the outcome of patients by a) continuously optimizing the device settings, b) preventing acute recurrences of heart failure, and c) improving clinical decision-making processes [2][3][4]. One of the major and most recent innovations is represented by the development of a hemodynamic sensor incorporated at the tip of a pacing lead.…”