[Single-lead DDD cardiac pacing: state of the art and future perspectives]

The electrical treatment of advanced atrioventricular block, with normal sinus node function, can be successfully and safely performed with single-lead atrial floating electrode VDD pacing. In comparison with two-lead DDD pacing, it offers some important advantages: easier and less time-consuming implantation procedures, simpler follow-up controls, and lower medium and long-term complication rates. However, should sinus node dysfunction develop, the atrium cannot be paced with this special kind of cardiac stimulation. For this reason, in the last few years, a particular research field has developed to overcome this problem. In this paper, the literature is reviewed, with special attention to the studies analyzing the commercially available leads and some prototypes implanted, outlining the pros and cons. The high stimulation energy, the inconstant atrial capture, and phrenic nerve stimulation are still unresolved problems. The reliability and efficacy of single-lead DDD pacing will presumably depend, in the future, on the development of preshaped, new-designed electrodes, with stable contact with the atrial wall, and on new stimulation waveforms. In this context, however, particular attention should be devoted to the correct atrial signal detection.