[Validity of telephone ECG multichannel transmission]

Transtelephonic ECG transmission is an established monitoring system for cardiac patients in many countries around the world with the exception of Germany. This study reports first experiences with a multichannel ECG system using nine leads. This system allows to analyze ECG for ischemic events in addition to cardiac arrhythmias. In this study the reliability of a modified lead registration procedure of the telephonic ECG system David 9 (MAP, München) was compared to conventional 12-lead ECG recording (Mingograph 7, Siemens) in 225 consecutive patients. Comparison was performed using the arm electrodes of the telephonic ECG system (Tel. ECG) within the armpit (group I) or at the wrists (group II). Placing the electrodes at the wrists improved sensitivity and specificity of electrocardiograpic abnormalities to conventional 12 lead ECG (Conv. ECG). Specificity for detection of anterior myocardial infarction was 0.95 (Tel. ECG vs. Conv. ECG), specificity was 1.0. For infero-posterior infarction these relations were 0.94 and 1.0 respectively. ST-segment changes have been detected in the Tel. ECG with 0.93 and 0.89 for specificity and sensitivity. The numbers of arrhythmia analysis were 1.0 and 0.7 for all rhythm disturbances. Detection of atrial fibrillation was less reliable due to short recording time and low amplitude of the transmitted signal. Specificity and sensitivity for detection of ventricular arrhythmias were 1.0 and 0.89. Optimizing the placement of arm electrodes to the wrist instead of armpits as done up to now improved the reliability of the telephonic transmitted ECG. This telephonic ECG system then enables a reliable registration of ischemic and arrhythmic events.