Ventriculoventricular delay optimization of a cardiac resynchronization device

Cardiac resynchronization therapy (CRT) has become a standard option for patients with severe low cardiac function and mild to severe heart failure. However, its potential has not been maximized to date, as the optimal atrioventricular delay, ventriculoventricular (VV) delay, and tachy therapy settings remain unknown. Here, data from various studies have been used to estimate several CRT settings.Three search words—interventricular interval, VV delay, and interventricular delay with cardiac resynchronization therapy—were entered into PubMed. The methods used to optimize VV delay included ultrasonography, radioisotope diagnosis, scintigraphy, electrocardiography, Swan–Ganz catheterization, and thoracic impedance. Their populations and results were analyzed to identify convincing rules. Methods for VV delay optimization in the literature can be categorized into four patterns. Time and cost were high in several categories. Most studies concluded that their method was effective but no small amount of papers denied individual detailed optimization. There were some population biases in most papers. Individual optimization had a major impact in patients with ischemic heart disease but no significant impact in patients with non-ischemic heart diseases.In summary, CRT is an established therapy, but a well-controlled study is required to find conclusive methods for VV delay optimization.