Computer modeling and experimental validation on effect of bipolar electrode spacing on near field and far field electrogram amplitudes

Far field R wave (FF) oversensing is a common problem associated with dual chamber devices, which may result in delivery of inappropriate therapies. Optimizing bipolar electrode design to increase ratios of near field P wave (NF) to FF and thereby rejecting FF signals is one method of resolving this problem. The goal of this study is to evaluate the effect of bipolar interelectrode spacing (IE) associated with lead orientation in a computer model and to validate the results with a well-controlled study in eight canines. Both model and animal results show that the NF/FF ratios increased with smaller IE. Overall, the amplitude of NF was attenuated with smaller IE. However, the FF amplitude exhibited a larger attenuation resulting in an increased NF/FF.