Patent ID: 7856271

Claim:
A method for sensing cardiac activity in an atrium of a patient's heart, comprising: delivering a pulse to the atrium using an electrode configuration that includes at least a pulse cathode electrode; sensing cardiac activity in the atrium using a unipolar electrode configuration to provide a sensed signal wherein the unipolar electrode configuration does not include the pulse cathode electrode; determining the duration during which the voltage of the sensed signal falls below a threshold voltage by determining a time when the absolute value of the sensed voltage signal exceeds the absolute value of the threshold voltage; determining a time when the absolute value of the sensed voltage signal is below the absolute value of the threshold voltage; and calculating the interval between the time when the absolute value of the sensed voltage signal exceeds the absolute value of the threshold voltage and the time when the absolute value of the sensed voltage signal is below the absolute value of the threshold voltage; and comparing the determined duration to a parameter to determine whether the pulse caused an atrial evoked response.