A technique for long-term, continuous cardiac surveillance. A cassette tape is worn by the patient continuously while carrying out his/her usual activities. The patient simultaneously keeps a diary of palpitations or other symptoms during the recording period. Symptoms of palpitations can later be correlated with the presence or absence of arrhythmias (abnormal heart rhythms) on the holter tape. The recordings can be analyzed by a doctor at a later date. Named for the late american biophysicist norman holter.