A method for monitoring a biological cardiac pacemaker is provided. The method may include stimulating a heart at a region selected for implantation of a biological pacemaker and sensing at least one electrical signal indicative of a cardiac depolarization originating in the region selected for implantation of the biological pacemaker. The method may further include sensing at least one subsequent electrical signal produced by the heart and determining if the subsequent electrical signal originated in the region selected for the biological pacemaker or another region of the heart. In an alternative embodiment, the method may include determining a template time difference between two points on cardiac complexes sensed in two or more different cardiac locations during normal sinus rhythm. The method may further include determining a time difference between two points on a subsequent cardiac complex sensed in two or more different cardiac locations. The time differences may be compared to determine if the subsequently-sensed cardiac complex originates in a left ventricular biological pacemaker site or in another cardiac site.
