Medical device delivery assemblies are disclosed. The assembly may include a catheter-based delivery system. The assembly may include a pacing element to pace a patient's heart before, during, or after a procedure. The pacing element may be a detachable, implanting pacing element. The pacing element may be an implantable pacemaker and the implantable pacemaker may be disposed on a catheter-based delivery system. The assembly may include a prosthetic heart valve with one or more pacing elements on it. The pacing element may include a pacing strip or strips. These strips may be conductive or insulative. These strips may prevent, treat, or correct abnormal electrical communication in a heart.