date comment and physician portions of each archived tdr reading to the programmer an archived tdr display window as shown in fig3 is then displayed using up 44 and down 43 arrows the physician may highlight an archived tdr reading which will normally be the baseline reading or first reading archived after implantation depressing the select portion of the screen causes programmer 28 close the widow and to command the pacemaker to transmit the selected archived tdr reading including the electrode sampling and display options to the programmer where they are displayed the physician may then depress the up arrow to highlight the 34 obtain tdr reading 34 menu option then press select 50 this will cause a tdr reading to be generated as described above and superimposed over the archived tdr reading by highlighting and adjusting the 34 max millirho alarm 34 option the physician may specify a millirho value predetermined threshold by which if a tdr reading deviates in a relevant portion an indicating output warning signal such as a flashing light buzzer or 34 defective 34 screen display is generated high and low limits from the electrode portion of the display waveform may be represented as horizontal lines on the graphical display specifically minimum warning line 64 and maximum warning line 65 as shown in fig6 define the boundaries in which the entire electrode portion of the waveform is expected to fall if a waveform deviates from these limits defective legend 66 may be displayed on the screen preferably in a highly contrasting color and accompanied by an audible alarm fig6 shows a representative superimposed tdr reading in which archived reading 61 shows an electrode in good condition while current reading.