1. A system for facilitating diagnosis of cardiac rhythm disorders with the aid of a digital computer, comprising: an electrocardiogram (ECG) monitoring and recording device; a download station adapted to retrieve cutaneous action potentials recorded for a set time period by the ECG monitoring and recorded device as ECG data; a processor and memory within which code for execution by the processor is stored, further comprising: an identification module configured to identify a plurality of R-wave peaks in the ECG data; a calculation module configured to calculate a difference between recording times of successive pairs of the R-wave peaks and to determine a heart rate associated with each time difference; and a construction module configured to form an extended duration R-R interval plot over the set time period comprising each of the recording time differences and the associated heart rates; and a display operatively coupled to the processor, further comprising: an extended duration R-R interval plot with a temporal point of reference in the extended duration R-R interval plot; and at least one accompanying ECG plot comprising at least part of the ECG data preceding and following the temporal point of reference as context.