A thermally actuated power element comprising an actuator having a guide, defining a generally cylindrical bore extending between first and second guide ends. The software system automatically determines whether conditions associated with the software system warrant use of any diagnostic features that are not currently enabled. An elastic body which is disposed in the inserting hole perpendicular to an extending direction of the inserting hole has two opposite tightening arms and a connecting portion interconnected with opposite ends of the tightening arms. Confidence intervals or percentage ventricular pacing can also be displayed.