Comparison of VVIR, DDD, and DDDR Pacing

Abstract

In the past several years there has been continued improvement in pacemaker technology, resulting in the availability of a large variety of pacemaker generators and pacing modes. The introduction of single‐chamber rate modulated pacemakers provided a further improvement in pacing therapy. With the recent introduction of dual‐chamber rate responsive pacemakers, it is now possible to more closely restore physiological function with pacing in a large number of patients. In deciding which pacing mode is most beneficial to a given patient, it is essential to understand the various characteristics of the different pacing modes that are available. It is essential to have knowledge of the underlying electrophysiological characteristics of the patient and how they would be affected by the different modes available. The VVIR mode will control bradycardia and provide rate adaptation but at the expense of AV synchrony. The DDD mode will control bradycardia and provide AV synchrony, but will not provide rate adaptation in patients with chronotropic incompetence. The DDDR mode will control bradycardia, maintain AV synchrony, and provide far rate adaptation in the presence of chronotropic incompetence. The chronotropic response to physiological stress and/or pacemaker syndrome are major determining factors in the choice of the best pacing mode. The primary goal of pacing therapy is to restore the heart function as close as possible to normal. When at all possible, this should include provision of both AV synchrony and rate modulation. The DDDR mode is preferable in most patients since it is capable of providing both AV synchrony and rate response (except those with chronic supraventricular arrhythmias). The VVIR mode is as effective in patients who have chronic atrial fibrillation or frequent episodes of supraventricitar arrhythmias.